01592nas a2200181 4500008004100000022001400041245009800055210006900153260007100222300001400293490000700307520089800314100001901212700001701231700001901248700001501267856012801282 2005 eng d a0743-746300aKeggin ion mediated synthesis of hydrophobized pd nanoparticles for multifunctional catalysis0 aKeggin ion mediated synthesis of hydrophobized pd nanoparticles  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAR a2408-24130 v213 a

Development of simple and reliable protocols for the synthesis of organically soluble catalytically active metal nanoparticles is an important aspect of research in nanomaterials. We demonstrate herein the formation of Pd nanoparticles by reduction of aqueous Pd(NO3)(2) by photoexcited Keggin ions (phosphotungstate anions). This results in the formation of Pd nanoparticles capped with with Keggin ions that render the particles negatively charged. The Keggin ion capped Pd nanoparticles may then be phase transferred into nonpolar organic solvents such as toluene by electrostatic complexation with cationic surfactants such as octadecylamine at the liquid-liquid interface. This results in a new class of catalyst wherein both the Pd core and Keggin ion shell may be used in a range of catalytic reactions leading to a truly multifunctional catalyst dispersible in organic solvents.

1 aMandal, Sujata1 aDas, Amitava1 aSrivastava, R.1 aSastry, M. uhttps://library.ncl.res.in/content/keggin-ion-mediated-synthesis-hydrophobized-pd-nanoparticles-multifunctional-catalysis-001050nas a2200169 4500008004100000245008200041210006900123260000800192300001600200490000700216520046600223100002600689700002000715700001700735700002300752856010500775 2011 eng d00aBorazine as a sensor for fluoride ion: a computational and experimental study0 aBorazine as a sensor for fluoride ion a computational and experi cMAY a3636–36390 v523 a

The computational and experimental studies have revealed that even simple molecule like borazine can act as a sensor for fluoride ions. This study further reported the various binding modes of analytes using quantum chemical calculations and the nature of such interactions have been examined using electron density surface analysis. Total charge transfer analysis (qCT) correlates well with the binding affinities of analytes with the borazine receptor.

1 aKesharwani, Manoj, K.1 aSuresh, Moorthy1 aDas, Amitava1 aGanguly, Bishwajit uhttps://library.ncl.res.in/content/borazine-sensor-fluoride-ion-computational-and-experimental-study01779nas a2200169 4500008004100000245011900041210006900160260000800229300001600237490000800253520113800261100001801399700002201417700002101439700001701460856013201477 2011 eng d00aComparative study of porphyrin derivatives in monolayers at the air-water interface and in langmuir-blodgett films0 aComparative study of porphyrin derivatives in monolayers at the  cMAR a8066–80730 v5193 a

The orientation and aggregation of various porphyrin derivatives at the air–water interface and in Langmuir–Blodgett films were investigated. Monolayer properties of these molecules, where long alkyl chain(s) were covalently bound through different functionality of varying hydrophilicity were studied by measuring surface pressure area isotherms. Such derivatives, where ether functionality (functionalities) was (were) used for linking long alkyl chain(s), did not form uniform monolayer; instead they were found to form multilayer clusters or aggregates on the water surface. On the other hand, porphyrin derivative functionalized at the four peripheral phenyl rings with eight hexadecyl ether chains formed stable spherical vesicles when deposited on mica. Tetra N-alkyl pyridinium porphyrins with long alkyl chain were found to form various phases on the water surface. Evidence of transition from horizontal orientation to vertical orientation of porphyrin rings of porphyrin molecules having C14 chains was observed. This type of transition was lost with the porphyrin molecule with a relatively smaller chain (C8).

1 aGhosh, Amrita1 aMahato, Prasenjit1 aChoudhury, Sipra1 aDas, Amitava uhttps://library.ncl.res.in/content/comparative-study-porphyrin-derivatives-monolayers-air-water-interface-and-langmuir-blodgett01326nas a2200157 4500008004100000245013300041210006900174260000800243300001600251520069100267100002100958700002000979700002400999700001701023856012801040 2011 eng d00aCompetitive binding of Ba2+and Sr2+ to 18-crown-6 in a receptor with a 1-methoxyanthraquinone analogue as the other binding site0 aCompetitive binding of Ba2and Sr2 to 18crown6 in a receptor with cOCT a4680–46903 a

Owing to their immense biological significance, development of sensors for the selective detection of alkaline earth metal ions has attracted vast research interest. In this article we have reported the synthesis, characterisation and ion binding studies of a new RuII-polypyridyl-crown-anthraquinone complex (5). Studies confirm selective binding of BaII, SrII and CaII ions, with Kmath image > Kmath image >> Kmath image, over all other metal ions, to the crown ether moiety and not to the methoxy anthraquinone component, the latter being the second binding site available and known for its affinity towards alkaline earth metal ions from one of our previous reports.

1 aBanerjee, Tanmay1 aSuresh, Moorthy1 aGhosh, Hirendra, N.1 aDas, Amitava uhttps://library.ncl.res.in/content/competitive-binding-ba2and-sr2-18-crown-6-receptor-1-methoxyanthraquinone-analogue-other01186nas a2200193 4500008004100000245012700041210006900168260000800237300001400245490000800259520048300267100001800750700001800768700001700786700002100803700002300824700001700847856012800864 2011 eng d00aDiamine derivative of a ruthenium(II)-polypyridyl complex for chemodosimetric detection of nitrite ion in aqueous solution0 aDiamine derivative of a rutheniumIIpolypyridyl complex for chemo cFEB a115–1190 v3723 a

Nitrite is quite an abundant anion in the environment. It, however, becomes toxic to human life, as well as aquatic animals when present above the permissible concentration level. We have reported here a Ru(II)-polypyridyl-based complex (1) for chemodosimetric detection of nitrite ion in aqueous solution. Formation of the new triazole based complex, generated by reaction of 1 and N2O3, is ascertained by comparing its properties with a presynthesised triazole complex.

1 aGhosh, Amrita1 aDas, Priyadip1 aSaha, Sukdeb1 aBanerjee, Tanmay1 aBhatt, Harshad, B.1 aDas, Amitava uhttps://library.ncl.res.in/content/diamine-derivative-rutheniumii-polypyridyl-complex-chemodosimetric-detection-nitrite-ion01768nas a2200169 4500008004100000245008600041210006900127260000800196300001600204490000700220520117600227100001901403700001801422700001701440700002601457856011501483 2011 eng d00aExciton-coupled charge-transfer dynamics in a porphyrin J-aggregate/TiO 2 complex0 aExcitoncoupled chargetransfer dynamics in a porphyrin Jaggregate cMAR a3458–34640 v173 a

Exciton-coupled charge-transfer (CT) dynamics in TiO2 nanoparticles (NP) sensitized with porphyrin J-aggregates has been studied by femtosecond time-resolved transient absorption spectroscopy. J-aggregates of 5,10,15-triphenyl-20-(3,4-dihydroxyphenyl) porphyrin (TPPcat) form CT complexes on TiO2 NP surfaces. Catechol-mediated strong CT coupling between J-aggregate and TiO2 NP facilitates interfacial exciton dissociation for electron injection into the conduction band of the TiO2 nanoparticle in pulse width limited time (<80 fs). Here, the electron-transfer (<80 fs) process dominates over the intrinsic exciton-relaxation process (J-aggregates: ca. 200 fs) on account of exciton-coupled CT interaction. The parent hole on J-aggregates is delocalized through J-aggregate excitonic coherence. As a result, holes immobilized on J-aggregates are spatially less accessible to electrons injected into TiO2, and thus the back electron transfer (BET) process is slower than that of the monomer/TiO2 system. The J-aggregate/porphyrin system shows exciton spectral and temporal properties for better charge separation in strongly coupled composite systems.

1 aVerma, Sandeep1 aGhosh, Amrita1 aDas, Amitava1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/exciton-coupled-charge-transfer-dynamics-porphyrin-j-aggregatetio-2-complex02700nas a2200217 4500008004100000245005900041210005700100260000800157300001400165490000700179520203200186100002002218700002402238700002602262700001902288700002302307700002802330700002002358700001702378856008702395 2011 eng d00aFolding and unfolding movements in a [2]pseudorotaxane0 aFolding and unfolding movements in a 2pseudorotaxane cDEC a138–1440 v763 a

A new dibenzo[24]crown-8 derivative (1) was synthesized and functionalized with aromatic moieties such as naphthalene and coumarin units. These two fluorophores are known to form an effective FRET (Forster resonance energy transfer) pair, and this formed the basis for the design of this host crown ether derivative. Results of the steady-state and time-resolved fluorescence studies confirmed the resonance energy transfer between the donor naphthalene moiety and acceptor coumarin fragment, while NMR spectra and computational studies support a folded conformation for the uncomplexed crown ether 1. This was found to form an inclusion complex, a [2]pseudorotaxane type with imidazolium ion derivatives as the guest molecules with varying alkyl chain lengths ([C4mim]+ or [C10mim]+). The host crown ether (1) tends to adopt an open conformation on formation of the interwoven inclusion complex (1·[C4mim]+ or 1·[C10mim]+). This change in conformation, from the folded to a open one, was predicted by computational as well as 1H NMR studies and was confirmed by single crystal X-ray structure for one (1·[C4mim]+) of the two inclusion complexes. The increase in the effective distance between the naphthalene and coumarin moieties in the open conformation of these inclusion complexes was also supported by the decrease in the effective FRET process that was operational between naphthalene and coumarin moieties in the free molecule (1). Importantly, this inclusion complex formation was found to be reversible, and in the presence of a stronger base/polar solvent, such as triethyl amine/DMSO, the deprotonation/effective solvation of the cationic imidizolium ions ([C4mim]+ or [C10mim]+) resulted in decomplexation or dethreading with restoration of the original emission spectra for 1, which signifies the subsequent increase in the FRET process. Thus we could demonstrate that a molecular folding-unfolding type of movement in the crown ether derivative could be induced by chemical input as an imidazolium ion.

1 aSuresh, Moorthy1 aMandal, Amal, Kumar1 aKesharwani, Manoj, K.1 aAdarsh, N., N.1 aGanguly, Bishwajit1 aKanaparthi, Ravi, Kumar1 aSamanta, Anunay1 aDas, Amitava uhttps://library.ncl.res.in/content/folding-and-unfolding-movements-2pseudorotaxane02457nas a2200157 4500008004100000245019700041210006900238260000800307300001600315520175900331100002102090700002202111700001702133700002602150856012302176 2011 eng d00aInterfacial electron transfer dynamics of two newly synthesized catecholate bound ruII polypyridyl-based sensitizers on TiO2 nanoparticle surface - a femtosecond pump probe spectroscopic study0 aInterfacial electron transfer dynamics of two newly synthesized  cSEP a4187–41973 a

Two new catecholate-bound RuII–polypyridine based sensitizers, (2,2′-bipyridine){ethyl 3-(4-hydroxyphenyl)-2-[(4′-methyl-2,2′-bipyridinyl-4-carbonyl)amino]propionate}{4-[2-(4′-methyl-2,2′-bipyridinyl-4-yl)vinyl]benzene-1,2-diol)}ruthenium(II) hexafluorophosphate (5) and [(2,2′-bipyridine)-(4-2,2′-bipyridinyl-4-yl-phenol)-(4-{2-(4′-methyl-2,2′-bipyridinyl-4-yl)vinyl}benzene-1,2-diol)]ruthenium(II) hexafluorophosphate (6) with secondary electron-donating groups (tyrosine and phenol, respectively) were synthesized and characterized. Steady-state optical absorption and emission studies confirm strong coupling between the sensitizers and TiO2 nanoparticles. Femtosecond visible transient absorption spectroscopy has been employed to study interfacial electron transfer (IET) dynamics in the dye–nanoparticle systems to explore the influence of the secondary electron-donating groups on IET dynamics. Electron injection into the conduction band of nanoparticulate TiO2 has been confirmed by detection of the conduction band electrons in TiO2 ([e–]TiO2CB) and radical cation of the adsorbed dye (D·+) in real time monitored by transient absorption spectroscopy. A single exponential and pulse-width limited (< 100 fs) electron injection has been observed. Back electron transfer (BET) dynamics have been studied by monitoring the decay kinetics of the injected electron in the conduction band of TiO2 and by the recovery of the ground state bleach. BET dynamics in dye–TiO2 systems for complexes 5 and 6 have been compared with those of [bis(2,2′-bpy)-(4-{2-(4′-methyl-2,2′-bipyridinyl-4-yl)vinyl}benzene-1,2-diol)]ruthenium(II) hexafluorophosphate (7), which does not have a secondary electron-donating group.

1 aBanerjee, Tanmay1 aRawalekar, Sachin1 aDas, Amitava1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/interfacial-electron-transfer-dynamics-two-newly-synthesized-catecholate-bound-ruii01568nas a2200205 4500008004100000245014000041210006900181260000800250300001600258490000700274520081900281100001801100700001801118700002101136700001901157700002401176700002001200700001701220856012501237 2011 eng d00aPhotoactive RuII-polypyridyl complexes that display sequence selectivity and high-affinity binding to duplex DNA through groove binding0 aPhotoactive RuIIpolypyridyl complexes that display sequence sele cFEB a2089–20980 v173 a

The duplex-DNA binding properties of a nonintercalating polypyridyl ruthenium(II) complex that incorporates a linear extended ligand with a catechol moiety has been probed with a variety of photo- and biophysical techniques. These studies reveal that the complex groove binds to DNA sequences biphasically, and displays binding constants equivalent to those of high-affinity metallointercalators. The complex also displays preferential binding to AT-rich sequences. Changes in the structure of the coordinated catechol ligand and the incorporation of intercalating ancillary ligands into the complex were found to modulate both the optical-binding response and binding parameters of the system, which indicates that the catechol moiety plays a crucial role in the observed enhancement to binding affinities.

1 aGhosh, Amrita1 aDas, Priyadip1 aGill, Martin, R.1 aKar, Prasenjit1 aWalkar, Michael, G.1 aThomas, Jim, A.1 aDas, Amitava uhttps://library.ncl.res.in/content/photoactive-ruii-polypyridyl-complexes-display-sequence-selectivity-and-high-affinity02533nas a2200169 4500008004100000245015500041210006900196260000800265300001400273490000700287520185900294100001902153700001902172700001702191700002602208856012902234 2011 eng d00aPhotophysical properties of ligand localized excited state in ruthenium(ii) polypyridyl complexes: a combined effect of electron donor-acceptor ligand0 aPhotophysical properties of ligand localized excited state in ru cAUG a9765-97730 v403 a

We have synthesized ruthenium(II) polypyridyl complexes (1) Ru(II)(bpy)2(L1), (2) Ru(II)(bpy)2(L2) and (3) Ru(II)(bpy)(L1)(L2), where bpy = 2,2′-bipyridyl, L1 = 4-[2-(4′-methyl-2,2′-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) and L2 = 4-(N,N-dimethylamino-phenyl)-(2,2′-bipyridine) and investigated the intra-ligand charge transfer (ILCT) and ligand–ligand charge transfer (LLCT) states by optical absorption and emission studies. Our studies show that the presence of electron donating –NMe2 functionality in L2 and electron withdrawing catechol fragment in L1 ligands of complex 3 introduces low energy LLCT excited states to aboriginal MLCT states. The superimposed LLCT and MLCT state produces redshift and broadening in the optical absorption spectra of complex 3 in comparison to complexes 1 and 2. The emission quantum yield of complex 3 is observed to be extremely low in comparison to that of complex 1 and 2 at room temperature. This is attributed to quenching of the 3MLCT state by the low-emissive 3LLCT state. The emission due to ligand localized CT state (ILCT and LLCT) of complexes 2 and 3 is revealed at 77 K in the form of a new luminescence band which appeared in the 670–760 nm region. The LLCT excited state of complex 3 is populated either via direct photoexcitation in the LLCT absorption band (350–700 nm) or through internal conversion from the photoexcited 3MLCT (400–600 nm) states. The internal conversion rate is determined by quenching of the 3MLCT state in a time resolved emission study. The internal conversion to LLCT and ILCT excited states are observed to be as fast as ∼200 ps and ∼700 ps for complexes 3 and 2, respectively. The present study illustrates the photophysical property of the ligand localized excited state of newly synthesized heteroleptic ruthenium(II) polypyridyl complexes.

1 aVerma, Sandeep1 aKar, Prasenjit1 aDas, Amitava1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/photophysical-properties-ligand-localized-excited-state-rutheniumii-polypyridyl-complexes00896nas a2200193 4500008004100000245008100041210006900122260000800191300001400199490000700213520024200220100001800462700002400480700002600504700002400530700002300554700001700577856010800594 2011 eng d00aReceptor design and extraction of inorganic fluoride ion from aqueous medium0 aReceptor design and extraction of inorganic fluoride ion from aq cMAY a7398-74000 v473 a

A receptor with acidic methylene hydrogens is found to act as an efficient binding mode for F−. This reagent could as well be used for selective and quantitative extraction of F− from the aqueous solution of NaF and sea water.

1 aDas, Priyadip1 aMandal, Amal, Kumar1 aKesharwani, Manoj, K.1 aSuresh, Eringathodi1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/receptor-design-and-extraction-inorganic-fluoride-ion-aqueous-medium00770nas a2200169 4500008004100000245009500041210006900136260000800205300001600213490000700229520016400236100002200400700001700422700002100439700001700460856012300477 2011 eng d00aSolvent-dependent aggregation behavior of a new Ru(ii)-polypyridyl based metallosurfactant0 aSolventdependent aggregation behavior of a new Ruiipolypyridyl b cSEP a11074-110760 v473 a

Variation of the solvent polarity leads to the formation of vesicles and reverse vesicles of a newly synthesized amphiphilic Ru(II)-polypyridyl complex.

1 aMahato, Prasenjit1 aSaha, Sukdeb1 aChoudhury, Sipra1 aDas, Amitava uhttps://library.ncl.res.in/content/solvent-dependent-aggregation-behavior-new-ruii-polypyridyl-based-metallosurfactant01341nas a2200157 4500008004100000245012300041210006900164260000800233300001400241490000600255520073900261100002401000700002001024700001701044856012201061 2011 eng d00aStudies on [3]pseudorotaxane formation from a bis-azacrown derivative as host and imidazolium ion-derivatives as guest0 aStudies on 3pseudorotaxane formation from a bisazacrown derivati cMAR a4811-48170 v93 a

A new host molecule, having two azacrown derivatives bridged by luminescent naphthalene diimide functionality, is found to form a [3]pseudorotaxane derivative with imidazolim ion-based guest molecules in non-polar solvents through hydrogen-bonded adduct formation. Depending upon the length of the covalent linker that links the imidazolium ion and the luminescent naphthalene fragment in the guests, the [3]pseudorotaxane adducts adopt different conformation or orientation with varying π–π/donor–acceptor interaction. The mechanism for the naphthalene-based luminescence quenching by NDI fragment on adduct formation was found to be a combination of static, as well as dynamic with static quenching as the dominant one.

1 aMandal, Amal, Kumar1 aSuresh, Moorthy1 aDas, Amitava uhttps://library.ncl.res.in/content/studies-3pseudorotaxane-formation-bis-azacrown-derivative-host-and-imidazolium-ion01715nas a2200205 4500008004100000245010600041210006900147260000800216300001400224490000800238520099700246100001801243700002201261700001801283700002401301700002101325700001701346700001701363856012901380 2011 eng d00aUrea/thiourea derivatives and Zn(II)-DPA complex as receptors for anionic recognition-a brief account0 aUreathiourea derivatives and ZnIIDPA complex as receptors for an cOCT a175–1860 v1233 a

This review covers few examples of anion complexation chemistry, with a special focus on urea/thiourea-based receptors and Zn(II)-dipicolyl amine-based receptors. This article specially focuses on structural aspects of the receptors and the anions for obtaining the desire specificity along with an efficient receptor–anion interaction. Two types of receptors have been described in this brief account; first one being the strong hydrogen bond donor urea/thiourea derivatives, which binds the anionic analytes through hydrogen bonded interactions; while, the second type of receptors are coordination complexes, where the coordination of the anion to the metal centre. In both the cases the anion binding modulate the energy gap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and thereby the spectroscopic response. Appropriate choice of the signalling unit may allow probing the anion binding phenomena through visual detection.

1 aDas, Priyadip1 aMahato, Prasenjit1 aGhosh, Amrita1 aMandal, Amal, Kumar1 aBanerjee, Tanmay1 aSaha, Sukdeb1 aDas, Amitava uhttps://library.ncl.res.in/content/ureathiourea-derivatives-and-znii-dpa-complex-receptors-anionic-recognition-brief-account00954nas a2200169 4500008004100000245013800041210006900179260000800248300001400256490000700270520029900277100001800576700002600594700002000620700001700640856012700657 2011 eng d00aZn(II) and Cd(II)-based complexes for probing the enzymatic hydrolysis of Na4P2O7 by alkaline phosphatase in physiological conditions0 aZnII and CdIIbased complexes for probing the enzymatic hydrolysi cSEP a8118-81200 v473 a

Newly synthesized Zn(II) and Cd(II)-based complexes show unique selectivity towards inorganic pyrophosphate (PPi) in 100% aqueous medium at pH = 7.4 and act as a "turn-on" and "turn-off" real-time assay, respectively, for the evaluation of the enzymatic activity of alkaline phosphatase.

1 aDas, Priyadip1 aSourish, Bhattacharya1 aSandhya, Mishra1 aDas, Amitava uhttps://library.ncl.res.in/content/znii-and-cdii-based-complexes-probing-enzymatic-hydrolysis-na4p2o7-alkaline-phosphatase01418nas a2200181 4500008004100000245009400041210006900135260000800204300001600212520077500228100001801003700001801021700002601039700001601065700002301081700001701104856011501121 2011 eng d00aZnII-2,2?:6?,2?-terpyridine-based complex as fluorescent chemosensor for PPi, AMP and ADP0 aZnII2262terpyridinebased complex as fluorescent chemosensor for  cJUL a3050–30583 a

A new ZnII–2,2′:6′,2″-terpyridine complex, derivatized with a coumarin moiety (L1Zn), acts as a fluorescent chemosensor for different biologically important phosphates like PPi, AMP and ADP in mixed aqueous media. Depending on the proportion of the aqueous fraction present in the solvent mixture, L1Zn shows a preference for different phosphate moieties at physiological pH. In an aqueous acetonitrile (2:3, v/v) medium this reagent shows a preference for AMP as compared to ADP, ATP and PPi. The binding affinities of L1Zn with different phosphate ions and associated shifts in the electronic spectra were rationalized by DFT calculations. Such an example of a receptor that is selective for AMP under physiological conditions is rare in the literature.

1 aDas, Priyadip1 aGhosh, Amrita1 aKesharwani, Manoj, K.1 aRamu, Vadde1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/znii-2262-terpyridine-based-complex-fluorescent-chemosensor-ppi-amp-and-adp01794nas a2200193 4500008004100000245018400041210006900225260000800294300001600302490000700318520102100325100002201346700001801368700002301386700002401409700002001433700001701453856013001470 2011 eng d00aZn(II)-cyclam based chromogenic sensors for recognition of atp in aqueous solution under physiological conditions and their application as viable staining agents for microorganism0 aZnIIcyclam based chromogenic sensors for recognition of atp in a cMAR a4162–41700 v503 a

Two chromogenic complexes, L.Zn (where L is (E)-4-((4-(1,4,8,11-tetraazacyclotetradecan-1-ylsulfonyl)phenyl)diazenyl)-N,N-dimethylaniline) and its [2]pseudorotaxane form (α-CD.L.Zn), were found to bind preferentially to adenosine triphosphate (ATP), among all other common anions and biologically important phosphate (AMP, ADP, pyrophosphate, and phosphate) ions in aqueous HEPES buffer medium of pH 7.2. Studies with live cell cultures of prokaryotic microbes revealed that binding of these two reagents to intercellular ATP, produced in situ, could be used in delineating the Gram-positive and the Gram-negative bacteria. More importantly, these dyes were found to be nontoxic to living microbes (eukaryotes and prokaryotes) and could be used for studying the cell growth dynamics. Binding to these two viable staining agents to intercellular ATP was also confirmed by spectroscopic studies on cell growth in the presence of different respiratory inhibitors that influence the intercellular ATP generation.

1 aMahato, Prasenjit1 aGhosh, Amrita1 aMishra, Sanjiv, K.1 aShrivastav, Anupama1 aMishra, Sandhya1 aDas, Amitava uhttps://library.ncl.res.in/content/znii-cyclam-based-chromogenic-sensors-recognition-atp-aqueous-solution-under-physiological01865nas a2200193 4500008004100000245012300041210006900164260000800233300001400241490000700255520115700262100001801419700002601437700002101463700002401484700002301508700001701531856012301548 2012 eng d00aAlternative approach: a highly selective dual responding fluoride sensor having active methylene group as binding site0 aAlternative approach a highly selective dual responding fluoride cJAN a2263-22710 v103 a

A newly designed phosphonium derivative (L) having active methylene functionality, shows unusual preference towards F− over all other anions. The binding process through C–H⋯F− hydrogen bond formation was probed by monitoring the changes in either electronic or luminescence spectra. Changes in both cases are significant enough to allow visual detection. The loss of molecular flexibility of L on forming L·F− effectively interrupts the non-radiative deactivation pathway and accounts for the observed switch on fluorescence response. The results of the time-resolved emission studies for L and L·F− using a time-correlated single photon counting technique further corroborate this presumption. The excellent preference of L towards F− is attributed to an efficient hydrogen bonding interaction between the strongly polarized methylene protons and F−, which delineates the subtle difference in the affinity among other competing anionic analytes like CN−, H2PO4−, CH3CO2−, etc. The relative affinities of various anions and the preferential binding of F− to reagent L are also rationalized using computational studies.

1 aDas, Priyadip1 aKesharwani, Manoj, K.1 aMandal, Amal, K.1 aSuresh, Eringathodi1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/alternative-approach-highly-selective-dual-responding-fluoride-sensor-having-active02612nas a2200169 4500008004100000245011400041210006900155260000800224300001400232490000600246520198900252100001802241700001802259700001802277700001702295856013002312 2012 eng d00aHighly selective and dual responsive test paper sensor of Hg2+/ Cr3+ for naked eye detection in neutral water0 aHighly selective and dual responsive test paper sensor of Hg2 Cr cMAR a3714-37210 v23 a

A highly selective and sensitive colorimetric and fluorogenic sensor (L1) for Hg2+/Cr3+ is reported. This reagent (L1) was synthesized by reacting 4-((4 (dimethylamino)phenyl)diazenyl)benzene-1-sulfonyl chloride, which has a dimethylaminophenyldiazenyl fragment as a photoactive signalling unit, with 2,2′-(3,3′-azanediylbis(propane-3,1-diyl))diisoindoline-1,3-dione as the receptor fragment. The reagent was characterized by standard analytical and spectroscopic techniques. Electronic spectral studies revealed that the reagent was selective for Hg2+ and Cr3+ in the presence of all other metal ions of Group 1A, IIA and all other common transition metal ions. On binding of L1 to the Hg2+ or Cr3+ centres, a new intense absorption band with a λmax of 509 nm appeared with associated changes in the visually detectable solution colour from yellow to red. Fluorescence spectral studies revealed a significant enhancement in the emission intensities upon coordination to Hg2+ or Cr3+ without any change in the emission wavelength. This could be explained by the efficient interruption of the photo induced electron transfer signalling mechanism involving an unshared pair of electrons from the central tertiary amine centre. An easy to prepare paper test kit, which was obtained by soaking the filter paper in a dichloromethane solution of L1, presents an approach that could be successfully used in the detection of Hg2+ or Cr3+ ions present in neutral aqueous media. This indicates the potential application of this dip strip type sensor for the detection of Hg2+ and Cr3+ in neutral aqueous environments without any spectroscopic instrumentation. Importantly, this reagent binds specifically to Cr3+ in the presence of an excess of iodide ions, which act as a masking agent for Hg2+. To the best of our knowledge, there are very few examples of detection limits lower than the present test strip for Hg2+ in the literature, while, for Cr3+, no such report is available.

1 aDas, Priyadip1 aGhosh, Amrita1 aBhatt, Hitesh1 aDas, Amitava uhttps://library.ncl.res.in/content/highly-selective-and-dual-responsive-test-paper-sensor-hg2-cr3-naked-eye-detection-neutral02275nas a2200169 4500008004100000245016000041210006900201260000800270300001600278490000700294520159700301100002201898700001701920700002101937700001701958856013001975 2012 eng d00aInterfacial and film formation behavior of photoactive Ru(ii)bipyridyl based metallosurfactants and a rare example of a monolayer based logic gate approach0 aInterfacial and film formation behavior of photoactive Ruiibipyr cDEC a1096–11050 v773 a

Three derivatives of tris(bipyridyl)–ruthenium(II) complexes with different alkyl-chain lengths (nC18H37 (1), nC14H29 (2) and nC10H21 (3)) were synthesised. All these complexes behaved as an amphiphile and their surface properties were studied at the air–water interface by measuring surface pressure–area (Π–A) isotherms. The surface morphology of the resulting films at the air–water interface was also studied by using Brewster angle microscopy. Mean molecular areas of these complexes were measured from the Π–A isotherms, which were approximately 200 Å2, thereby indicating a parallel arrangement of the Ru–bipyridyl moiety of the complexes. Mono- and multilayer Langmuir–Blodgett (LB) films were formed on different solid surfaces with transfer ratios close to one. Similarities in the absorption and fluorescence spectra of these amphiphiles in solution as well as in LB films deposited on a quartz surface confirmed the successful transfer of these films onto the substrates. The latter provided information about the arrangements of metallosurfactant molecules within the LB films. The two-dimensional concentrations of these films were calculated from the Lambert–Beer law as well as from the Π–A isotherm, which confirmed regular and reproducible transfer of the complex monolayers from the air–water interface onto the quartz surface. The surface morphology of these films on various substrates was characterised by atomic force microscopy. Furthermore, by oxidising the monolayer of complex 3, a one-input sequential logic gate was constructed.

1 aMahato, Prasenjit1 aSaha, Sukdeb1 aChoudhury, Sipra1 aDas, Amitava uhttps://library.ncl.res.in/content/interfacial-and-film-formation-behavior-photoactive-ruiibipyridyl-based-metallosurfactants00937nas a2200181 4500008004100000245013400041210006900175260000800244300001400252490000700266520026000273100001700533700002200550700001800572700002100590700001700611856012700628 2012 eng d00aInterrupted PET coupled TBET process for the design of a specific receptor for Hg2+ and its intracellular detection in MCF7 cells0 aInterrupted PET coupled TBET process for the design of a specifi cJUL a9293-92950 v483 a

A new coumarin–rhodamine conjugate constitutes a unique example of the interrupted PET coupled TBET response for developing an imaging reagent for determining the intracellular distribution of Hg2+ in MCF7 cells exposed to [Hg2+] as low as 2 ppb.

1 aSaha, Sukdeb1 aMahato, Prasenjit1 aBaidya, Mithu1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/interrupted-pet-coupled-tbet-process-design-specific-receptor-hg2-and-its-intracellular02539nas a2200229 4500008004100000245014400041210006900185260000800254300001800262490000700280520158900287653013501876100001802011700002402029700002802053700001802081700002302099700002302122700002102145700001702166856012602183 2012 eng d00aNew chemodosimetric reagents as ratiometric probes for cysteine and homocysteine and possible detection in living cells and in blood plasma0 aNew chemodosimetric reagents as ratiometric probes for cysteine  cNOV a15382–153930 v183 a

In this work, we have rationally designed and synthesized two new reagents (L1 and L2), each bearing a pendant aldehyde functionality. This aldehyde group can take part in cyclization reactions with β- or γ-amino thiols to yield the corresponding thiazolidine and thiazinane derivatives, respectively. The intramolecular charge-transfer (ICT) bands of these thiazolidine and thiazinane derivatives are distinctly different from those of the molecular probes (L1 and L2). Such changes could serve as a potential platform for using L1 and L2 as new colorimetric/fluorogenic as well as ratiometric sensors for cysteine (Cys) and homocysteine (Hcy) under physiological conditions. Both reagents proved to be specific towards Cys and Hcy even in the presence of various amino acids, glucose, and DNA. Importantly, these two chemodosimetric reagents could be used for the quantitative detection of Cys present in blood plasma by using a pre-column HPLC technique. Such examples are not common in contemporary literature. MTT assay studies have revealed that these probes have low cytotoxicity. Confocal laser scanning micrographs of cells demonstrated that these probes could penetrate cell membranes and could be used to detect intracellular Cys/Hcy present within living cells. Thus, the results presented in this article not only demonstrate the efficiency and specificity of two ratiometric chemodosimeter molecules for the quantitative detection of Cys and Hcy, but also provide a strategy for developing reagents for analysis of these vital amino acids in biological samples.

10acharge transfer; chemodosimetric detection; cysteine/ homocysteine sensors; fluorescent probes; imaging agents; ratiometric probes1 aDas, Priyadip1 aMandal, Amal, Kumar1 aChandar, Nellore, Bhanu1 aBaidya, Mithu1 aBhatt, Harshad, B.1 aGanguly, Bishwajit1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/new-chemodosimetric-reagents-ratiometric-probes-cysteine-and-homocysteine-and-possible02251nas a2200205 4500008004100000245015200041210006900193260000800262300001400270490000700284520148800291100001901779700002101798700001901819700001401838700001701852700002301869700002401892856012901916 2012 eng d00aPhotosensitization of nanoparticulate TiO2 using a Re(I)-polypyridyl complex: studies on interfacial electron transfer in the ultrafast time domain0 aPhotosensitization of nanoparticulate TiO2 using a ReIpolypyridy cAPR a8192-81980 v143 a

We have synthesized a new photoactive rhenium(I)-complex having a pendant catechol functionality [Re(CO)3Cl(L)] (1) (L is 4-[2-(4′-methyl-2,2′-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) for studying the dynamics of the interfacial electron transfer between nanoparticulate TiO2 and the photoexcited states of this Re(I)-complex using femtosecond transient absorption spectroscopy. Our steady state absorption studies revealed that complex 1 can bind strongly to TiO2 surfaces through the catechol functionality with the formation of a charge transfer (CT) complex, which has been confirmed by the appearance of a new red-shifted CT band. The longer wavelength absorption band for 1, bound to TiO2 through the proposed catecholate functionality, could also be explained based on the DFT calculations. Dynamics of the interfacial electron transfer between 1 and TiO2 nanoparticles was investigated by studying kinetics at various wavelengths in the visible and near infrared regions. Electron injection into the conduction band of the nanoparticulate TiO2 was confirmed by detection of the conduction band electron in TiO2 (Image ID:c2cp24105f-t1.gif) and the cation radical of the adsorbed dye (1˙+) in real time as monitored by transient absorption spectroscopy. A single exponential and pulse-width limited (<100 fs) electron injection was observed. Back electron transfer dynamics was determined by monitoring the decay kinetics of 1˙+ and Image ID:c2cp24105f-t2.gif.

1 aKar, Prasenjit1 aBanerjee, Tanmay1 aVerma, Sandeep1 aSen, Anik1 aDas, Amitava1 aGanguly, Bishwajit1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/photosensitization-nanoparticulate-tio2-using-rei-polypyridyl-complex-studies-interfacial01981nas a2200157 4500008004100000245017200041210006900213260000800282300001800290490000800308520132800316100002201644700001701666700001701683856012301700 2012 eng d00aRare example of TICT based optical responses for the specific recognition of Cr3+ by a 2,2?:6?,2?-terpyridine derivative and demonstration of multiple logic operations0 aRare example of TICT based optical responses for the specific re cJUL a17448–174570 v1163 a

Chemosensor L showed a nonlinear fluorescence response on specific binding to Cr3+ ion in the presence of various alkali, alkaline-earth, transition, and lanthanide metal ions. A luminescence band with maxima at 512 nm for L was observed (λext = 330 nm) for a twisted intramolecular charge transfer (TICT) transition following antienergy gap law behavior. However, normal energy gap law behavior prevailed on formation of a new nonluminescent charge transfer complex, Mn+·L. For paramagnetic metal ions, paramagnetism induced luminescence quenching could have also contributed to this. A new switched on fluorescence response at λems of 356 nm (λext of 330 nm) was observed due to Franck–Condon charge transfer (FC-CT) transition only on the formation of a complex, (Cr3+)2·L. Spectral studies revealed a unique dynamic coordination behavior and migration of Cr3+ from the terpyridyl fragment to the NNMe2 center of L as a function of the varying concentration of another ion (Zn2+) and the subtle difference in the binding affinities of the terpyridyl moiety toward Cr3+ and Zn2+. Further, spectral responses of L toward Zn2+, different concentration of Cr3+, H+ and on subsequent addition of F– as different ionic inputs could be correlated well for demonstrating various basic and combinatorial circuits.

1 aMahato, Prasenjit1 aSaha, Sukdeb1 aDas, Amitava uhttps://library.ncl.res.in/content/rare-example-tict-based-optical-responses-specific-recognition-cr3-2262-terpyridine01765nas a2200229 4500008004100000245009600041210006900137260000800206300001600214490000700230520098300237100002201220700001701242700001501259700001901274700002801293700002701321700002601348700002301374700001701397856012101414 2012 eng d00aRatiometric detection of Cr3+ and Hg2+ by a naphthalimide-rhodamine based fluorescent probe0 aRatiometric detection of Cr3 and Hg2 by a naphthalimiderhodamine cJAN a1769–17770 v513 a

Newly synthesized rhodamine derivatives, L1 and L2, are found to bind specifically to Hg2+ or Cr3+ in presence of large excess of other competing ions with associated changes in their optical and fluorescence spectral behavior. These spectral changes are significant enough in the visible region of the spectrum and thus, allow the visual detection. For L1, the detection limit is even lower than the permissible [Cr3+] or [Hg2+] in drinking water as per standard U.S. EPA norms; while the receptor, L2 could be used as a ratiometric sensor for detection of Cr3+ and Hg2+ based on the resonance energy transfer (RET) process involving the donor naphthalimide and the acceptor Cr3+/Hg2+-bound xanthene fragment. Studies reveal that these two reagents could be used for recognition and sensing of Hg2+/Cr3+. Further, confocal laser microscopic studies confirmed that the reagent L2 could also be used as an imaging probe for detection of uptake of these ions in A431 cells.

1 aMahato, Prasenjit1 aSaha, Sukdeb1 aSuresh, E.1 aDi Liddo, Rosa1 aParnigotto, Pier, Paolo1 aConconi, Maria, Teresa1 aKesharwani, Manoj, K.1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/ratiometric-detection-cr3-and-hg2-naphthalimide-rhodamine-based-fluorescent-probe01954nas a2200217 4500008004100000245014700041210006900188260000800257300001400265490000700279520116100286100001701447700002201464700002301486700001501509700002501524700001801549700002101567700001701588856013101605 2012 eng d00aRecognition of Hg 2+ and Cr 3+ in physiological conditions by a rhodamine derivative and its application as a reagent for cell-imaging studies0 aRecognition of Hg 2 and Cr 3 in physiological conditions by a rh cDEC a336–3450 v513 a

A new rhodamine-based receptor, derivatized with an additional fluorophore (quinoline), was synthesized for selective recognition of Hg2+ and Cr3+ in an acetonitrile/HEPES buffer medium of pH 7.3. This reagent could be used as a dual probe and allowed detection of these two ions by monitoring changes in absorption and the fluorescence spectral pattern. In both instances, the extent of the changes was significant enough to allow visual detection. More importantly, the receptor molecule could be used as an imaging reagent for detection of Hg2+ and Cr3+ uptake in live human cancer cells (MCF7) using laser confocal microscopic studies. Unlike Hg(ClO4)2 or Hg(NO3)2 salts, HgCl2 or HgI2 failed to induce any visually detectable change in color or fluorescence upon interaction with L1 under identical experimental conditions. Presumably, the higher covalent nature of HgII in HgCl2 or HgI2 accounts for its lower acidity and its inability to open up the spirolactam ring of the reagent L1. The issue has been addressed on the basis of the single-crystal X-ray structures of L1·HgX2 (X– = Cl– or I–) and results from other spectral studies.

1 aSaha, Sukdeb1 aMahato, Prasenjit1 aReddy, Upendar, G.1 aSuresh, E.1 aChakrabarty, Arindam1 aBaidya, Mithu1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/recognition-hg-2-and-cr-3-physiological-conditions-rhodamine-derivative-and-its-application01290nas a2200205 4500008004100000245011900041210006900160260000800229300001600237490000700253520056400260100002400824700002000848700001800868700001500886700001800901700002100919700001700940856012700957 2012 eng d00aRecognition of Hg2+ion through restricted imine isomerization: crystallographic evidence and imaging in live cells0 aRecognition of Hg2ion through restricted imine isomerization cry cJUN a2980–29830 v143 a

A newly synthesized imine-based receptor (L) showed remarkable specificity toward the Hg2+ ion in aqueous media over other metal ions. Coordination of L to Hg2+ induces a turn-on fluorescence response. This was explained based on the restricted imine isomerization along with PET on coordination to Hg2+. X-ray structural evidence tends to favor a C–C bond rotation rather than C═N isomerization for adopting a favorable conformation in L for coordination to Hg2+. This reagent could be used for imaging the accumulation of Hg2+ ions in HeLa cells.

1 aMandal, Amal, Kumar1 aSuresh, Moorthy1 aDas, Priyadip1 aSuresh, E.1 aBaidya, Mithu1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/recognition-hg2ion-through-restricted-imine-isomerization-crystallographic-evidence-and01866nas a2200169 4500008004100000245014500041210006900186260000800255300001600263490000700279520120700286100002401493700002001517700001801537700001701555856012401572 2012 eng d00aRestricted conformational flexibility of a triphenylamine derivative on the formation of host-guest complexes with various macrocyclic hosts0 aRestricted conformational flexibility of a triphenylamine deriva cMAR a3906–39170 v183 a

Herein, we report the host–guest-type complex formation between the host molecules cucurbit[7]uril (CB[7]), β-cyclodextrin (β-CD), and dibenzo[24]crown-8 ether (DB24C8) and a newly synthesized triphenylamine (TPA) derivative 1X3 as the guest component. The host–guest complex formation was studied in detail by using 1H NMR, 2D NOESY, UV/Vis fluorescence, and time-resolved emission spectroscopy. The chloride salt of the TPA derivative was used for recognition studies with CB[7] and β-CD in an aqueous medium. The restricted internal rotation of the guest molecule on complex formation with either of these two host molecules was reflected in the enhancement of the emission quantum yield and the average excited-state lifetime for the triphenylamine-based excited states. Studies with DB24C8 as the host molecule were performed in dichloromethane, a medium that maximizes the noncovalent interaction between the host and guest fragments. The Förster resonance energy transfer (FRET) process involving DB24C8 and 1(PF6)3, as the donor and acceptor fragments, respectively, was established by electrochemical, steady-state emission, and time-correlated single-photon counting studies.

1 aMandal, Amal, Kumar1 aSuresh, Moorthy1 aDas, Priyadip1 aDas, Amitava uhttps://library.ncl.res.in/content/restricted-conformational-flexibility-triphenylamine-derivative-formation-host-guest00902nas a2200193 4500008004100000245013700041210006900178260000800247300001400255490000700269520018100276100001700457700002500474700002200499700001600521700002200537700001700559856013200576 2012 eng d00aRhodamine-alginate conjugate as self-indicating gel beads for efficient detection and scavenging of Hg 2+ and Cr 3+ in aqueous media0 aRhodaminealginate conjugate as selfindicating gel beads for effi cNOV a1659-16610 v483 a

Effective extraction of Hg2+ and Cr3+ ions from aqueous media by novel rhodamine–alginate polymer-based highly fluorogenic, as well as colorimetric, chemosensor beads.

1 aSaha, Sukdeb1 aChhatbar, Mahesh, U.1 aMahato, Prasenjit1 aPraveen, L.1 aSiddhanta, A., K.1 aDas, Amitava uhttps://library.ncl.res.in/content/rhodamine-alginate-conjugate-self-indicating-gel-beads-efficient-detection-and-scavenging-hg01847nas a2200181 4500008004100000245009700041210006900138260000800207300001600215490000600231520119900237100001901436700001901455700002101474700001701495700002401512856012901536 2012 eng d00aSequential energy and electron transfer in polynuclear complex sensitized TiO2 nanoparticles0 aSequential energy and electron transfer in polynuclear complex s cMAY a1543–15480 v33 a

Polynuclear–polypyridyl complexes exhibit a directional energy-transfer property that can improve their photosensitization activity. In the present work, the energy-transfer process is explored in a trinuclear Ru2∧Os1 complex using transient absorption spectroscopy. This study reveals an efficient excitation energy transfer from the terminal (RuII complex) to the core (OsII complex) region in the ultrafast time domain (400 fs–40 ps). The excitation energy funnel is useful in improving the functionalized core activity. This is evidenced in an interfacial electron-transfer study of Ru2∧Os1, Ru2∧Ru1, and Os1 complex sensitized TiO2 nanoparticle (TiO2 NP) systems. The intramolecular energy transfer causes sequential excitation of the core part of the Ru2∧Os1 complex, which leads to multiexponential electron injection into TiO2 NP. Besides this, the electronic coupling between the metal ion centers stabilizes the positive charge within the trinuclear complex, which results in a slow charge recombination reaction. This study shows that polynuclear complexes can be very useful for their panchromatic effects, unidirectional energy- and electron-transfer properties.

1 aVerma, Sandeep1 aKar, Prasenjit1 aBanerjee, Tanmay1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/sequential-energy-and-electron-transfer-polynuclear-complex-sensitized-tio2-nanoparticles02211nas a2200181 4500008004100000245012700041210006900168260000800237300001600245490000700261520153200268100002401800700001801824700002201842700002001864700001701884856012801901 2012 eng d00aTaco complex derived from a bis-crown ether capable of executing molecular logic operation through reversible complexation0 aTaco complex derived from a biscrown ether capable of executing  cJUL a6789–68000 v773 a

As learned from natural systems, self-assembly and self-sorting help in interconnecting different molecular logic gates and thus achieve high-level logic functions. In this context, demonstration of important logic operations using changes in optical responses due to the formation of molecular assemblies is even more desirable for the construction of a molecular computer. Synthesis of an appropriate divalent as well as a luminescent crown ether based host 1 and paraquat derivatives, 2(PF6)2 and 3(PF6)2, as guests helped in demonstrating a reversible [3](taco complex) (1·{2(PF6)2}2 or 1·{3(PF6)2}2) formation in nonpolar solvent. Detailed 1H NMR studies revealed that two paraquat units were bound cooperatively by the two crown units in 1. Because of preorganization, the flexible host molecule 1 adopts a folded conformation, where each of two paraquat units remain sandwiched between the two aromatic units of each folded crown ether moiety in 1. Disassembly of the “taco” complex in the presence of KPF6 and reassembly on subsequent addition of DB18C6 was initially demonstrated by 1H NMR spectral studies, which were subsequently corroborated through luminescence spectral studies. Further, luminescence spectral responses as output signals with appropriate and two independent molecular inputs could be correlated to demonstrate basic logic operation like OR and YES gates, while the results of the three molecular inputs could be utilized to demonstrate important logic operation like an INHIBIT gate.

1 aMandal, Amal, Kumar1 aDas, Priyadip1 aMahato, Prasenjit1 aAcharya, Suhash1 aDas, Amitava uhttps://library.ncl.res.in/content/taco-complex-derived-bis-crown-ether-capable-executing-molecular-logic-operation-through00928nas a2200193 4500008004100000245011800041210006900159260000800228300001200236490000700248520023900255100002300494700001800517700001700535700001800552700002100570700001700591856012600608 2013 eng d00aCN? specific turn-on phosphorescent probe with probable application for enzymatic assay and as an imaging reagent0 aCN specific turnon phosphorescent probe with probable applicatio cOCT a255-2570 v493 a

A new “turn-on” luminescence probe for imaging the uptake of 0.2 ppm inorganic CN− in live HeLa cells as well as for probing the CN− generation through an enzymatic process in a virtual aqueous medium at appropriate pH.

1 aReddy, Upendar, G.1 aDas, Priyadip1 aSaha, Sukdeb1 aBaidya, Mithu1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/cn-specific-turn-phosphorescent-probe-probable-application-enzymatic-assay-and-imaging02257nas a2200205 4500008004100000022001400041245020800055210006900263260011000332300001400442490000700456520133800463100001801801700002401819700002301843700001801866700002101884700001701905856012901922 2013 eng d a1477-052000aDesigning a thiol specific fluorescent probe for possible use as a reagent for intracellular detection and estimation in blood serum: kinetic analysis to probe the role of intramolecular hydrogen bonding0 aDesigning a thiol specific fluorescent probe for possible use as aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT a6604-66140 v113 a

A new and simple chemodosimetric probe L-1 is utilized for the selective detection of biothiols in the presence of other relevant amino acids under physiological conditions (pH = 7.4). This eventually led to a turn-off luminescence response due to an effective photoinduced electron transfer based signaling mechanism. A comparison of the results of the fluorescence kinetic analysis and H-1 NMR studies of the reaction between thiol and L-1 or the analogous compound L-2 revealed the role of intramolecular hydrogen bonding in activating the imine functionality towards nucleophilic addition. Such an example is not common in contemporary literature. Conventional MTT assay studies revealed that this probe (L-1) has low cytotoxicity. Results of the cell imaging studies revealed that this probe was cell membrane permeable and could detect the intracellular distribution of biothiols within living HeLa cells. Furthermore, our studies with human blood plasma demonstrated the possibility of using this reagent for the quantitative optical detection of total biothiols in biological fluid. Such an example for the detection of biothiols in real biological samples is rare in the contemporary literature. These results clearly demonstrate the possibility of using this reagent in medicinal biology and diagnostic applications.

1 aDas, Priyadip1 aMandal, Amal, Kumar1 aReddy, Upendar, G.1 aBaidya, Mithu1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/designing-thiol-specific-fluorescent-probe-possible-use-reagent-intracellular-detection-002415nas a2200169 4500008004100000245008000041210006900121260000800190300001400198490000600212520184400218100002002062700002402082700001502106700001702121856010702138 2013 eng d00aFirst demonstration of two-step FRET in a synthetic supramolecular assembly0 aFirst demonstration of twostep FRET in a synthetic supramolecula cMAR a2380-23860 v43 a

We report a trichromophoric pseudorotaxane (3NPC) that demonstrates a two-step FRET-based relay comprising of primary donor–primary acceptor/secondary donor–secondary acceptor pairs. To achieve this, naphthalene (1) and coumarin (3) were used as the primary donor and secondary acceptor, respectively; while pyrene (2 or T) unit, having spectral overlap with both 1 and 3, was used as the primary acceptor as well as the secondary donor. Results of time resolved and steady-state emission studies reveal that sequential resonance energy transfer (FRET 1 → 2 → 3) and direct resonance energy transfer (FRET 1 → 3) processes are operational simultaneously. In the sequential energy transfer process (1 → 2 → 3) of the triad system, pyrene acts as a transmitter and makes the whole supramolecular assembly behave as a linear energy transferring wire. Sensitised emission of the coumarin moiety, i.e. the secondary and eventual final acceptor, offers the possibility of evaluating the performance of this linear trichromophoric system by one and two-step FRET mechanisms. Formation of an interwoven complex between the host (NCC24O8) and the guest (T) components, utilizing various non-bonding interactions (intercomponent [N+–H⋯O], [C–H⋯O] and π–π stacking interactions) has been confirmed by 1H NMR studies in solution and a single crystal X-structural study in the solid state. The formation constant (Kf = 2.31 × 103 M−1) for the [2]pseudorotaxane was evaluated using isothermal titration calorimetric studies. The complex gives rise to the first crystal structure of a self-assembled [2]pseudorotaxane that demonstrates sequential two-step FRET based energy transfer in a self-assembled triad that is held in an assembly through non-covalent interactions, such as hydrogen bonding and π–π stacking.

1 aSuresh, Moorthy1 aMandal, Amal, Kumar1 aSuresh, E.1 aDas, Amitava uhttps://library.ncl.res.in/content/first-demonstration-two-step-fret-synthetic-supramolecular-assembly01373nas a2200169 4500008004100000022001400041245014300055210006900198260011000267300001400377490000700391520061500398100002101013700001701034700002401051856012801075 2013 eng d a1144-054600aInterfacial charge recombination of Os(II)-polypyridyl-resorcinol complex on oleic acid capped TiO2 surface: what determines the dynamics?0 aInterfacial charge recombination of OsIIpolypyridylresorcinol co aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUL a3100-31080 v373 a

Femtosecond transient absorption spectroscopic studies of an osmium(II)-polypyridyl-resorcinol complex, 1, on oleic acid capped TiO2 have been carried out and the results have been compared with our previous studies on poly(vinyl) alcohol capped TiO2. While on both these surfaces the complex exhibits a single exponential <120 fs injection, the back electron transfer reaction is slower on the oleic acid capped TiO2 surface early on while it is faster on the same surface at longer times than on poly(vinyl)alcohol capped TiO2. The probable origin of these disparate observations has been analyzed.

1 aBanerjee, Tanmay1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/interfacial-charge-recombination-osii-polypyridyl-resorcinol-complex-oleic-acid-capped-002265nas a2200229 4500008004100000022001400041245013900055210006900194260007100263300001400334490000700348520137500355100002401730700002001754700002601774700002701800700001901827700002301846700002301869700001701892856012601909 2013 eng d a0022-326300aMolecular interactions, proton exchange, and photoinduced processes prompted by an inclusion process and a [2]pseudorotaxane formation0 aMolecular interactions proton exchange and photoinduced processe a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAUG a9004-90120 v783 a

Appropriate design of the host and guest components allows formation of a novel [2]pseudorotaxane complex with an interrupted photoinduced electron transfer (PET)-coupled fluorescence resonance energy transfer (FRET) response. This is the first example of an inclusion complex with NO6-based azacrown ether as the host unit (H). Different guest molecules (G1, G2, G3, and G4) with varying stopper size are used for the studies. Unlike G1, G2, and G3, G4 with a relatively bulkier stopper fails to form a [2]pseudorotaxane complex. Isothermal titration microcaloiimetry measurements reveal a systematic increase in the association constant for H.G1, H.G2, and H.G3 with a change in the stopper size. Thermodynamic data suggest that the formation of H.G1/H.G2/H.G3 is exclusively driven by a large positive entropic gain (T Delta S = 19.69/26.80/21.81 kJ.mol(-1)), while the enthalpy change is slightly negative for H.G1/H.G3 (-2.61/-1.97 kJ.mol(-1)) and slightly positive for H.G2 (Delta H = 5.98 kJ.mol(-1)). For these three inclusion complexes, an interrupted PET-coupled FRET response is observed with varying efficiency, which is attributed to the subtle differences in acidity of the NH2+ unit of the guest molecules and thus the proton exchange ability between the host and respective guest. This is substantiated by the results of the computational studies.

1 aMandal, Amal, Kumar1 aSuresh, Moorthy1 aKesharwani, Manoj, K.1 aGangopadhyay, Monalisa1 aAgrawal, Manoj1 aBoricha, Vinod, P.1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/molecular-interactions-proton-exchange-and-photoinduced-processes-prompted-inclusion-001771nas a2200217 4500008004100000022001400041245013700055210006900192260011000261300001600371490000700387520090800394100001701302700002301319700001801342700001801360700001501378700002101393700001701414856012201431 2013 eng d a1477-922600aNew chemodosimetric probe for the specific detection of Hg2+ in physiological condition and its utilisation for cell imaging studies0 aNew chemodosimetric probe for the specific detection of Hg2 in p aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUL a15097-151050 v423 a

A dithiane derivative of BODIPY is synthesized. This new reagent could be used for the specific and instantaneous detection of Hg2+ in physiological condition. This dithiane reagent reacts specifically with Hg2+ to regenerate the parent BODIPY-aldehyde with consequential change in visually detectable optical responses and this provides the possibility of using this reagent as a colorimetric probe or as a fluorescent biomarker/imaging reagent. Further, non-covalent interactions could be utilized for formation of an inclusion complex with biologically benign beta-cyclodextrin for enhancing its solubility in aqueous environment and this included adduct could be used as a fluorescent marker and imaging reagent for Hg2+. Uptake of Hg2+ ions in live HeLa cells, exposed to a solution having Hg2+ ion concentration as low as 2 ppb, could also be detected by confocal laser microscopic studies.

1 aSaha, Sukdeb1 aAgarwalla, Hridesh1 aGupta, Hariom1 aBaidya, Mithu1 aSuresh, E.1 aGhosh, Sudip, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/new-chemodosimetric-probe-specific-detection-hg2-physiological-condition-and-its-000989nas a2200205 4500008004100000022001400041245012900055210006900184260011000253300001400363490000700377520015100384100002300535700002100558700001500579700002100594700002300615700001700638856012800655 2013 eng d a1359-734500aNew receptor with a FRET based fluorescence response for selective recognition of fumaric and maleic acids in aqueous medium0 aNew receptor with a FRET based fluorescence response for selecti aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAUG a9818-98200 v493 a

Preferential binding of a new reagent to fumaric acid could be utilized for its estimation in aqueous medium and in commercial fruit juice.

1 aReddy, Upendar, G.1 aLo, Rabindranath1 aRoy, Sovan1 aBanerjee, Tanmay1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/new-receptor-fret-based-fluorescence-response-selective-recognition-fumaric-and-maleic-002017nas a2200169 4500008004100000245020800041210006900249260000800318300001600326490000800342520127700350100002101627700002701648700001701675700002601692856012901718 2013 eng d00aNewly designed resorcinolate binding for Ru(II)- and Re(I)- polypyridyl complexes on oleic acid capped tio2 in non-aqueous solvent: prolonged charge separation and substantial thermalized 3MLCT injection0 aNewly designed resorcinolate binding for RuII and ReI polypyridy cJAN a3084–30920 v1173 a

Femtosecond pump–probe spectroscopic studies on a series of newly synthesized resorcinol-based Ru(II) and Re(I) complexes on oleic acid capped TiO2 nanoparticles have been carried out in chloroform, and the results are compared with those of the catechol analogues. The ruthenium complex shows biexponential injection; the second component arises due to injection from the thermally equilibrated 3MLCT states as a result of a weaker strength of the resorcinolate binding. Also, in comparison with catechol binding, as a result of a greater diffusion of the injected electrons into TiO2, the back electron transfer (BET) is slowed down significantly for the ruthenium complex. These are distinctive observations for any mononuclear ruthenium–polypyridyl–enediol complex reported thus far. However, the rhenium complex educes single exponential ultrafast injection (<120 fs) because of apparent injection in a high density of states and shows the most prominent results with ∼50% slowdown in the charge recombination rate as compared to the analogous catechol bound system. These results exemplify the probable development of highly capable sensitizer dyes with resorcinol as the anchoring group for the development of efficient dye-sensitized solar cells.

1 aBanerjee, Tanmay1 aKaniyankandy, Sreejith1 aDas, Amitava1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/newly-designed-resorcinolate-binding-ruii-and-rei-polypyridyl-complexes-oleic-acid-capped02505nas a2200205 4500008004100000022001400041245016500055210006900220260007100289300001600360490000700376520165600383100001802039700002802057700002102085700002302106700002302129700001702152856013002169 2013 eng d a0020-166900aRole of metal ion in specific recognition of pyrophosphate ion under physiological conditions and hydrolysis of the phosphoester linkage by alkaline phosphatase0 aRole of metal ion in specific recognition of pyrophosphate ion u a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a11034-110410 v523 a

Complexes synthesized from Zn(II), Cu(II), and Cd(II), using a dipicolyl amine derivative (L), showed unique specificity toward pyrophosphate ion (PPi or P4O74-) among all other common anionic analytes, including different biologically significant phosphate ion (PO43-, H2PO42-) or phosphate-ion-based nucleotides, such as AMP, ADP, ATP, and CTP. However, the relative affinities of PPi toward these three metal complexes were found to vary and follow the order K-a(L.Zn-PPi) > are given in units of (L.Cu-PPi)(a) >= K-a(L.Cd-PPi). Luminescence responses of the receptor L were substantial on binding to Zn2+ and Cd2+, while relatively a much smaller luminescence response was observed in the presence of Cu2+. Luminescence responses of L.M-PPi (M is Zn2+, Cd2+, and Cu2+) were further modified on binding to the PPi ion. This could be utilized for quantitative detection of PPi in physiological condition as well as for developing a real time ``turn-on'' (for L.Zn and L.Cu) and ``turn-off'' (for L.Cd) fluorescence assay for evaluating the enzymatic activity of alkaline phosphatase (ALP). Experimental results revealed how the subtle differences in the binding affinities between PPi and M in L.M (M is Zn2+, Cd2+, and Cu2+), could influence the cleavage of the phosphoester linkage in PPi by ALP. The DFT calculations further revealed that the hydrolytic cleavage of the metal ion coordinated phosphoester bond is kinetically faster than that for free PPi and thus, rationalized the observed difference in the cleavage of the phosphoester bond by an important mammalian enzyme such as ALP in the presence of different metal complexes.

1 aDas, Priyadip1 aChandar, Nellore, Bhanu1 aChourey, Shishir1 aAgarwalla, Hridesh1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/role-metal-ion-specific-recognition-pyrophosphate-ion-under-physiological-conditions-and-001761nas a2200169 4500008004100000245013500041210006900176260000800245300001400253490000600267520111800273100001601391700001701407700002501424700001701449856012501466 2013 eng d00aSelf-assembly of modified rhodamine-6G with tri-block copolymer: unusual vesicles formation, pH sensing and dye release properties0 aSelfassembly of modified rhodamine6G with triblock copolymer unu cDEC a1150-11550 v13 a

A new rhodamine-6G derivative having a C18-alkyl chain self-assembles with an amphiphilic tri-block copolymer and forms stable vesicles in water or in water–ethanol (4 : 1, v/v) medium. The stability of the spirolactam form of the rhodamine-6G derivative in these vesicular structures, along with studies of controlled dye release and pH sensing are discussed. Transmission electron micrographs and DLS analyses confirm the formation of vesicular structures. Atomic force microscopy (AFM) images show that the self assembled tri-block copolymer-octadecyl rhodamine vesicles form near spherical nanostructures with a size ranging from 80 to 110 nm. Furthermore, the vesicular system is disassembled under acidic conditions, releasing the cargo which are an integral part of the vesicle. Dye-release studies showed that the release rates of the loaded dye in the vesicles could be well-controlled as a function of the media pH. These results offer an opportunity to use these nanovesicles as imaging reagents for probing media pH with their simultaneous use as nanocarriers for intracellular drug delivery.

1 aPraveen, L.1 aSaha, Sukdeb1 aJewrajka, Suresh, K.1 aDas, Amitava uhttps://library.ncl.res.in/content/self-assembly-modified-rhodamine-6g-tri-block-copolymer-unusual-vesicles-formation-ph01835nas a2200169 4500008004100000245017600041210006900217260000800286300001600294490000700310520113300317100002101450700002701471700001701498700002601515856012401541 2013 eng d00aSynthesis, steady-state, and femtosecond transient absorption studies of resorcinol bound ruthenium(ii)- and osmium(ii)-polypyridyl complexes on nano-TiO2 surface in water0 aSynthesis steadystate and femtosecond transient absorption studi cAPR a5366–53770 v523 a

The synthesis of two new ruthenium(II)- and osmium(II)-polypyridyl complexes 3 and 4, respectively, with resorcinol as the enediol anchoring moiety, is described. Steady-state photochemical and electrochemical studies of the two sensitizer dyes confirm strong binding of the dyes to TiO2 in water. Femtosecond transient absorption studies have been carried out on the dye–TiO2 systems in water to reveal <120 fs and 1.5 ps electron injection times along with 30% slower back electron transfer time for the ruthenium complex 3. However, the corresponding osmium complex 4 shows strikingly different behavior for which only a <120 fs ultrafast injection is observed. Most remarkably, the back electron transfer is faster as compared to the corresponding catechol analogue of the dye. The origin and the consequences of such profound effects on the ultrafast interfacial dynamics are discussed. This Article on the electron transfer dynamics of the aforesaid systems reinforces the possibility of resorcinol being explored and developed as an extremely efficient binding moiety for use in dye-sensitized solar cells.

1 aBanerjee, Tanmay1 aKaniyankandy, Sreejith1 aDas, Amitava1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/synthesis-steady-state-and-femtosecond-transient-absorption-studies-resorcinol-bound02096nas a2200193 4500008004100000022001400041245013300055210006900188260007100257300001600328490000800344520132200352100002401674700002001698700001401718700001701732700002301749856013001772 2014 eng d a1932-744700aDesign of efficient metal-free organic dyes having an azacyclazine scaffold as the donor fragment for dye-sensitized solar cells0 aDesign of efficient metalfree organic dyes having an azacyclazin a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcSEP a20763-207710 v1183 a

The energy conversion efficiency of dye-sensitized solar cells derived from organic dye molecules has seen immense interest recently. In this work, we report a series of organic donor molecules with enhanced energy conversion efficiency using ?-spacers and cyanoacrylic acid as an anchoring group (2-6). Density functional theory (DFT) and time-dependent DFT calculations of these molecules have been performed to examine their electronic structures and absorption spectra before and after binding to the semiconductor titanium dioxide surface. The computational results suggest that dyes 4 and 6 have a larger driving force (Delta G(inject) = -1.66 and -1.80 eV, respectively) and light-harvesting efficiency (LHE = 0.99) in the series of donor molecules studied. Thus, these dyes should possess a larger short-circuit photocurrent density (J(sc)) compared to the other examined dyes. The reported Delta G(inject) (-1.62 eV) and LHE (0.98) for compound 1, calculated with the same level of theory, were lower than those of the designed 4 and 6 dyes. Furthermore, the DFT calculations showed that the open-circuit photovoltage (V-oc) is improved with the vertical dipole moment and number of photoinjected electrons for 4 and 6. Dyes 4 and 6 are expected to exhibit high solar-energy-to-electricity conversion.

1 aBiswas, Abul, Kalam1 aBarik, Sunirmal1 aSen, Anik1 aDas, Amitava1 aGanguly, Bishwajit uhttps://library.ncl.res.in/content/design-efficient-metal-free-organic-dyes-having-azacyclazine-scaffold-donor-fragment-dye-002517nas a2200193 4500008004100000245018100041210006900222260000800291300001600299490000800315520173800323100002302061700002202084700001902106700002602125700002302151700001702174856013202191 2014 eng d00aHydrogen bonding interaction between active methylene hydrogen atoms and an anion as a binding motif for anion recognition: experimental studies and theoretical rationalization0 aHydrogen bonding interaction between active methylene hydrogen a cMAR a2656–26660 v1183 a

Two new reagents, having similar spatial arrangements for hydrogen atoms of the active methylene functionalities, were synthesized and interactions of such reagents with different anionic analytes were studied using electronic spectroscopy as well as by using 1H and 31P NMR spectroscopic methods. Experimental studies revealed that these two reagents showed preference for binding to F– and OAc–. Detailed theoretical studies along with the above-mentioned spectroscopic studies were carried out to understand the contribution of the positively charged phosphonium ion, along with methylene functionality, in achieving the observed preference of these two receptors for binding to F– and OAc–. Observed differences in the binding affinities of these two reagents toward fluoride and acetate ions also reflected the role of acidity of such methylene hydrogen atoms in controlling the efficiencies of the hydrogen bonding in anion–Hmethylene interactions. Hydrogen bonding interactions at lower concentrations of these two anionic analytes and deprotonation equilibrium at higher concentration were observed with associated electronic spectral changes as well as visually detectable change in solution color, an observation that is generally common for other strong hydrogen bond donor functionalities like urea and thiourea. DFT calculations performed with the M06/6-31+G**//M05-2X/6-31G* level of theory showed that F– binds more strongly than OAc– with the reagent molecules. The deprotonation of methylene hydrogen atom of receptors with F– ion was observed computationally. The metal complex as reagent showed even stronger binding energies with these analytes, which corroborated the experimental results.

1 aAgarwalla, Hridesh1 aJana, Kalyanashis1 aMaity, Arunava1 aKesharwani, Manoj, K.1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/hydrogen-bonding-interaction-between-active-methylene-hydrogen-atoms-and-anion-binding-motif02182nas a2200205 4500008004100000022001400041245016400055210006900219260011000288300001600398490000700414520129900421100002101720700002401741700002401765700002301789700001701812700002601829856012101855 2014 eng d a1477-922600aNew Ru(II)/Os(II)-polypyridyl complexes for coupling to TiO2 surfaces through acetylacetone functionality and studies on interfacial electron-transfer dynamics0 aNew RuIIOsIIpolypyridyl complexes for coupling to TiO2 surfaces  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a13601-136110 v433 a

New Ru(II)- and Os(II)-polypyridyl complexes have been synthesized with pendant acetylacetone (acac) functionality for anchoring on nanoparticulate TiO2 surfaces with a goal of developing an alternate sensitizer that could be utilized for designing an efficient dye-sensitized solar cell (DSSC). Time-resolved transient absorption spectroscopic studies in the femtosecond time domain have been carried out. The charge recombination rates are observed to be very slow, compared with those for strongly coupled dye molecules having catechol as the anchoring functionality. The results of such studies reveal that electron-injection rates from the metal complex-based LUMO to the conduction band of TiO2 are faster than one would expect for an analogous complex in which the chromophoric core and the anchoring moiety are separated with multiple saturated C-C linkages. Such an observation is rationalized based on computational studies, and a relatively smaller spatial distance between the dye LUMO and the TiO2 surface accounted for this. Results of this study are compared with those for analogous complexes having a gem-dicarboxy group as the anchoring functionality for covalent binding to the TiO2 surface to compare the role of binding functionalities on electron-transfer dynamics.

1 aBanerjee, Tanmay1 aBiswas, Abul, Kalam1 aSahu, Tuhin, Subhra1 aGanguly, Bishwajit1 aDas, Amitava1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/new-ruiiosii-polypyridyl-complexes-coupling-tio2-surfaces-through-acetylacetone-001196nas a2200205 4500008004100000022001400041245014800055210006900203260011000272300001400382490000700396520032900403100002300732700002300755700001900778700002100797700002500818700001700843856013000860 2014 eng d a1359-734500aNovel fluorescence probe for estimation of cysteine/histidine in human blood plasma and recognition of endogenous cysteine in live Hct116 cells0 aNovel fluorescence probe for estimation of cysteinehistidine in  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a9899-99020 v503 a

A new Cu(II)-complex is used as a ``Turn-On'' luminescence probe for specific detection of endogenous Cys in live Hct116 cells and Cys present in human blood plasma without any interference from other amino acids, especially GSH and Hcy. Difference in the mechanistic pathway for Cys and His recognition is discussed.

1 aReddy, Upendar, G.1 aAgarwalla, Hridesh1 aTaye, Nandaraj1 aGhorai, Suvankar1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/novel-fluorescence-probe-estimation-cysteinehistidine-human-blood-plasma-and-recognition-002568nas a2200193 4500008004100000022001400041245006000055210005900115260011000174300001600284490000600300520188500306100002202191700001702213700001802230700002302248700001702271856008602288 2014 eng d a2046-206900aOverview of the recent developments on Hg2+ recognition0 aOverview of the recent developments on Hg2 recognition aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJUN a36140-361740 v43 a

Adverse influences of mercury on living organisms are well known. Despite efforts from various regulatory agencies, the build-up of Hg2+ concentration in the environment is of serious concern. This necessitates the search for new and efficient reagents for recognition and detection of Hg2+ in environmental samples as well as for application in diagnostics. Among various detection processes adopted for designing such reagents, generally methodologies that allow associated changes in spectra properties are preferred for the obvious ease in the detection process. Significant changes in the electronic spectral pattern in the visible region of the spectrum also induce detectable changes in solution colour for naked-eye detection and are useful for developing reagents for in-field sample analysis with yes-no type binary responses. However, reagents that allow detection of Hg2+ with associated fluorescence on response are useful for detection of Hg2+ in environmental samples, as well as for use as an imaging reagent, for detection of cellular uptake. High spin-orbit coupling constant for Hg2+ along with its high solvation energy in aqueous medium poses a challenge in developing efficient reagents with fluorescence on response that work in aqueous medium/physiological condition. To get around this problem, several methodologies, like conversion of rhodamine derivative spirolactam to strongly fluorescent xanthenes that form on binding to Hg2+, chemodosimetric reaction for generation of a new luminescent derivative, have been adopted. Apart from these, modified charge transfer processes on binding to Hg2+ have also been utilized for designing reagents for optical detection of Hg2+. Immobilization of such reagents on solid surfaces also led to the development of self-indicating Hg2+ ion scavengers. All such examples are discussed in the present review.

1 aMahato, Prasenjit1 aSaha, Sukdeb1 aDas, Priyadip1 aAgarwalla, Hridesh1 aDas, Amitava uhttps://library.ncl.res.in/content/overview-recent-developments-hg2-recognition-001840nas a2200169 4500008004100000022001400041245012100055210006900176260007100245300001600316490000800332520113900340100001901479700001701498700002401515856013101539 2014 eng d a1932-744700aSize quantization effects on interfacial electron transfer dynamics in Ru(II)-polypyridyl complex sensitized ZnO QDs0 aSize quantization effects on interfacial electron transfer dynam a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC a28898-289050 v1183 a

Quantum-size confinement in semiconductor material offers size based tunability of interband gap energy as well as intraband sublevels. In this work, size quantization of wide bandgap ZnO quantum dots has been explored in the study of interfacial charge separation reaction using a catechol functionalized Ru(II)polypyridyl complex as a photosensitizer molecule. Femtosecond time-resolved transient absorption studies have revealed multiple electron injection events based on discrete conduction band states of ZnO QDs. The electron injection rates have been rationalized for quantum confinement effects owing to different sizes of ZnO QDs. Furthermore, the size dependency of the intrinsic lifetime of electrons injected into discrete energy levels of ZnO QDs has been revealed in charge recombination reaction with the Ru(III)polypyridyl complex cation. The charge recombination dynamics reveals a competing trend of carrier confinement and carrier leak upon reducing particle size. This study shows the optimization of finite size effects in achieving better interfacial charge separation at the dye/semiconductor interface.

1 aVerma, Sandeep1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/size-quantization-effects-interfacial-electron-transfer-dynamics-ruii-polypyridyl-complex-001077nas a2200205 4500008004100000022001400041245017300055210006900228260011000297300001600407490000700423520019400430100002300624700001600647700001500663700001900678700002500697700001700722856013200739 2014 eng d a1359-734500aSpecific probe for Hg2+ to delineate even H+ in pure aqueous buffer/Hct116 colon cancer cells: Hg(II)-eta(2)-arene pi-interaction and a TBET-based fluorescence response0 aSpecific probe for Hg2 to delineate even H in pure aqueous buffe aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a14421-144240 v503 a

A new molecular probe that demonstrates a distinct TBET process, induced by the Hg(II)-eta(2)-arene pi-interaction, in pure aqueous medium with a large pseudo-Stokes shift of 200 nm.

1 aReddy, Upendar, G.1 aRamu, Vadde1 aRoy, Sovan1 aTaye, Nandaraj1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/specific-probe-hg2-delineate-even-h-pure-aqueous-bufferhct116-colon-cancer-cells-hgii-eta2-002116nas a2200217 4500008004100000022001400041245019300055210006900248260007100317300001400388490000800402520119800410100002101608700002401629700002301653700002401676700001701700700002301717700002601740856013201766 2014 eng d a1932-744700aSuperior grafting and state-of-the-art interfacial electron transfer rates for newly designed geminal dicarboxylate bound ruthenium(II)- and osmium(II)-polypyridyl dyes on TiO2 nanosurface0 aSuperior grafting and stateoftheart interfacial electron transfe a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcFEB a3864-38770 v1183 a

Two new Ru(II)-/Os(II)-polypyridyl based sensitizer dyes with geminal dicarboxylic acid group as the binding unit for superior grafting of the dye to TiO2 have been designed and synthesized. Steady-state photochemical studies of the two sensitizer dyes in presence of TiO2 in water confirm strong binding of the dyes to TiO2. Femtosecond transient absorption studies of these newly synthesized dyes on TiO2 nanosurface have been carried out in water and the results have been compared with those for the corresponding 4,4'-dicarboxy-2,2'-bipyridine analogues of the dyes. While the charge recombination rates are considerably slower, interestingly, the electron injection rates are very fast for multiple saturated C-C linkages present between the chromophoric core and the anchoring moiety. The origin and the consequences of such profound effects on the ultrafast interfacial dynamics are discussed. This is the first report on the ultrafast transient absorption studies of dyes with geminal dicarboxylic acid binding groups, which we believe will add significantly to the present research efforts toward the development of robust and efficient dyes for use in dye solar applications.

1 aBanerjee, Tanmay1 aBiswas, Abul, Kalam1 aReddy, Upendar, G.1 aSahu, Tuhin, Subhra1 aDas, Amitava1 aGanguly, Bishwajit1 aGhosh, Hirendra, Nath uhttps://library.ncl.res.in/content/superior-grafting-and-state-art-interfacial-electron-transfer-rates-newly-designed-geminal-003133nas a2200169 4500008004100000022001400041245013900055210006900194260011000263300001600373490000700389520237100396100002402767700001702791700002302808856013202831 2015 eng d a1463-907600aCan silicon substituted metal-free organic dyes achieve better efficiency compared to silicon free organic dyes? a computational study0 aCan silicon substituted metalfree organic dyes achieve better ef aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT a31093-311000 v173 a

The power conversion efficiency of metal-free organic dyes in dye-sensitized solar cells (DSSCs) is now comparable to ruthenium-based polypyridyl and zinc-based porphyrin dyes. We have computationally investigated the structural, electronic and optical properties of a series of metal free organic dyes and their corresponding silicon substituted dyes. The DFT and TD-DFT calculations revealed that silicon substituted organic dyes have higher efficiency than the corresponding silicon free organic dyes. The computational results showed that the presence of silole units as a spacer group can significantly affect the performance of DSSCs compared to typically using thiophene as a spacer unit. These results corroborate the experimental observations reported in the literature. The time-dependent density functional theory (TDDFT) calculations performed at the CPCM-CAM-B3LYP/6-31+G* level of theory showed better agreement with the experimental absorption spectra of some reported metal free organic dyes having silole in the spacer group compared to other functionals and are employed in this study. Indoline donor based dye 5 showed a much shorter absorption spectrum (absorption peak at 425 nm) and smaller electron injection driving force (Delta G(injection) = -1.77 eV) than the corresponding dye 8 containing silicon substituted indoline as a donor and a silole group as a spacer unit. lambda(max) = 502 nm and Delta G(injection) = -1.82 eV calculated for dye 8 are much larger than the corresponding silicon free dye 5. The silicon based dye 8 helps in achieving a much lower DGregeneration value than 5, which can facilitate the faster electron injection rate from the dye to the semiconductor TiO2. Dye 8 should also have a higher V-oc value compared to other dyes (5-7) due to favourable interaction with the electrolyte (I-/I-3(-)). The higher planarity and better conjugation in dye 8 facilitate the transfer of electrons from the dye molecules to the semiconductor TiO2. The calculations performed with phenyl protecting groups near the silicon center of the dye molecule 8 to diminish the dimerization process showed very similar optical properties as obtained with the corresponding unprotected dye system. The designed julolidine and pyrrolo-indolizine donor based dyes also showed a similar trend as observed for indoline donor based dyes.

1 aBiswas, Abul, Kalam1 aDas, Amitava1 aGanguly, Bishwajit uhttps://library.ncl.res.in/content/can-silicon-substituted-metal-free-organic-dyes-achieve-better-efficiency-compared-silicon-002518nas a2200277 4500008004100000022001400041245013400055210006900189260007500258300001400333490000700347520153500354653002101889653001501910653001201925653001901937653002601956100001601982700002101998700002102019700001802040700002002058700001702078700001702095856012802112 2015 eng d a0947-653900aCytostatic ruthenium(II)-platinum(II) bis(terpyridyl) anticancer complex that blocks entry into sphase by up-regulating p27(KIP1)0 aCytostatic rutheniumIIplatinumII bisterpyridyl anticancer comple aPOSTFACH 101161, 69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcJUN a9185-91970 v213 a

Cytostatic agents that interfere with specific cellular components to prevent cancer cell growth offer an attractive alternative, or complement, to traditional cytotoxic chemotherapy. Here, we describe the synthesis and characterization of a new binuclear Ru-II-Pt-II complex [Ru(tpy)(tpypma)Pt(Cl)(DMSO)](3+) (tpy=2,2:6,2-terpyridine and tpypma=4-([2,2:6,2-terpyridine]-4-yl)-N-(pyridin-2-ylmethyl)aniline), VR54, which employs the extended terpyridine tpypma ligand to link the two metal centres. In cell-free conditions, VR54 binds DNA by non-intercalative reversible mechanisms (K-b=1.3x10(5)M(-1)) and does not irreversibly bind guanosine. Cellular studies reveal that VR54 suppresses proliferation of A2780 ovarian cancer cells with no cross-resistance in the A2780CIS cisplatin-resistant cell line. Through the preparation of mononuclear Ru-II and Pt-II structural derivatives it was determined that both metal centres are required for this anti-proliferative activity. In stark contrast to cisplatin, VR54 neither activates the DNA-damage response network nor induces significant levels of cell death. Instead, VR54 is cytostatic and inhibits cell proliferation by up-regulating the cyclin-dependent kinase inhibitor p27(KIP1) and inhibiting retinoblastoma protein phosphorylation, which blocks entry into Sphase and results in G1 cell cycle arrest. Thus, VR54 inhibits cancer cell growth by a gain of function at the G1 restriction point. This is the first metal-coordination compound to demonstrate such activity.

10aantitumor agents10acytostatic10ap27KIP110aplatinum drugs10aruthenium terpyridine1 aRamu, Vadde1 aGill, Martin, R.1 aJarman, Paul, J.1 aTurton, David1 aThomas, Jim, A.1 aDas, Amitava1 aSmythe, Carl uhttps://library.ncl.res.in/content/cytostatic-rutheniumii-platinumii-bisterpyridyl-anticancer-complex-blocks-entry-sphase-101104nas a2200205 4500008004100000022001400041245009200055210006900147260000800216300001600224490000700240520042300247100001500670700001800685700001900703700002400722700002500746700001700771856011000788 2015 eng d a1359-734500aFluorescent probe for specific detection of cysteine in the lipid dense region of cells0 aFluorescent probe for specific detection of cysteine in the lipi cSEP a16932-169350 v513 a

A new cysteine (Cys) specific chemodosimetric reagent (ER-F) is used in imaging of endogenous Cys localized in the lipid dense region of the live Hct116 cells and the release of Cys within HepG2 cells from a drug following a biochemical transformation. A silica surface, modified with ER-F, could be used for quantitative estimation of Cys present in aqueous solution (pH 7.2) and in a human blood plasma (HBP).

1 aAli, Firoj1 aAnila, H., A.1 aTaye, Nandaraj1 aGonnade, Rajesh, G.1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/fluorescent-probe-specific-detection-cysteine-lipid-dense-region-cells02667nas a2200217 4500008004100000022001400041245014800055210006900203260011000272300001400382490000600396520175400402100002302156700002702179700003002206700002502236700001902261700002302280700001702303856012902320 2015 eng d a2050-750X00aFluorescent probes for the detection of cyanide ions in aqueous medium: cellular uptake and assay for beta-glucosidase and hydroxynitrile lyase0 aFluorescent probes for the detection of cyanide ions in aqueous  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT a9148-91560 v33 a

A chemodosimteric reagent (1) for the efficient detection of cyanide species (CN- and/or HCN) in aq. medium as well as under physiological conditions has been described. Selective reaction of the cyanide species with this reagent in the presence of all common interfering anions, amino acids and glutathione (GSH) led to the generation of the corresponding cyanohydrin derivative. The formation of the cyanohydrin derivative of the probe is associated with a visually detectable change in solution fluorescence in aq. buffer medium with 1.9 mu M NaCN, the threshold limit set by WHO for the safe drinking water and this makes this fluorogenic sensor an ideal candidate for in-field applications. An apparent switch on the luminescence response, ultralow detection limit, low response time, cell membrane permeability and insignificant toxicity are key features of a probe molecule, which gives it a distinct edge over previously reported chemodosimetric reagents for the detection of cyanide species (CN- or HCN) in an aqueous environment. This methodology could be used for developing a generalized and efficient fluorescence-based assay for crucial enzymes like beta-glucosidase and hydroxynitrile lyase. Furthermore, spectrally-resolved fluorescence microscopy measurements on single-cells revealed that this sensor molecule could also be used for imaging the cellular uptake of cyanide species from aq. solution contaminated with NaCN. Our results confirmed that statistical analysis of integrated intensity and transition energy obtained from the emission spectra collected over various microscopic sub-cellular regions can potentially be used to discriminate the effects of local cellular environments and that due to cyanide detection.

1 aAgarwalla, Hridesh1 aGangopadhyay, Monalisa1 aSharma, Dharmendar, Kumar1 aBasu, Santanu, Kumar1 aJadhav, Sameer1 aChowdhury, Arindam1 aDas, Amitava uhttps://library.ncl.res.in/content/fluorescent-probes-detection-cyanide-ions-aqueous-medium-cellular-uptake-and-assay-beta-001065nas a2200205 4500008004100000022001400041245008500055210006900140260007100209300001400280490000700294520032900301100002300630700001800653700001500671700001900686700002500705700001700730856011200747 2015 eng d a1523-706000aFRET-based probe for monitoring pH changes in lipid-dense region of Hct116 cells0 aFRETbased probe for monitoring pH changes in lipiddense region o a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV a5532-55350 v173 a

A rhodamine conjugate (L) with a pseudo Stokes shift of 165 nm is used for probing changes in solution pH under physiological conditions. This reagent is found to be nontoxic, and the luminescence response could be used for imaging changes in endogenous pH induced by dexamethanose (DMT) in the endoplasmic reticulum.

1 aReddy, Upendar, G.1 aAnila, H., A.1 aAli, Firoj1 aTaye, Nandaraj1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/fret-based-probe-monitoring-ph-changes-lipid-dense-region-hct116-cells-001939nas a2200181 4500008004100000022001400041245010000055210006900155260007100224300001600295490000800311520123300319100001901552700001601571700001701587700002401604856012901628 2015 eng d a1520-610600aHydrogen bond and ligand dissociation dynamics in fluoride sensing of Re(I)-polypyridyl complex0 aHydrogen bond and ligand dissociation dynamics in fluoride sensi a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV a14952-149580 v1193 a

Hydrogen bonding interaction plays an essential role in the early phases of molecular recognition and colorimetric sensing of various anions in aprotic media. In this work, the host-guest interaction between fac-[Re(CO)(3)Cl(L)] with L = 4-([2,2'-bipyridin]-4-yl)phenol and fluoride ions is investigated for the hydrogen bond dynamics and the changing local coordination environment. The stoichiometric studies using H-1 NMR and ESI-MS spectroscopies have shown that proton transfer in the H-bonded phenol-fluoride complex activates the dissociation of the CO ligand in the Re(I) center. The phenol-to-phenolate conversion during formation of HF2- ion induces nucleophilic lability of the CO ligand which is probed by intraligand charge transfer (ILCT) and ligand-to-metal charge transfer (LMCT) transitions in transient absorption spectroscopy. After photoexcitation, phenol-phenoxide conversion rapidly equilibrates in 280 fs time scale and the ensuing excited state [ReII(bpy(center dot-)-phenolate(-))(CO)(3)Cl]* undergoes CO dissociation in the ultrafast time scale of similar to 3 ps. A concerted mechanism of hydrogen cleavage and coordination change is established in anion sensing studies of the rhenium complex.

1 aVerma, Sandeep1 aAute, Sunil1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/hydrogen-bond-and-ligand-dissociation-dynamics-fluoride-sensing-rei-polypyridyl-complex-102406nas a2200217 4500008004100000022001400041245010000055210006900155260011000224300001400334490000600348520158500354100001601939700001501955700001901970700001801989700001602007700002502023700001702048856012302065 2015 eng d a2050-750X00aNew imaging reagents for lipid dense regions in live cells and the nucleus in fixed MCF-7 cells0 aNew imaging reagents for lipid dense regions in live cells and t aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAUG a7177-71850 v33 a

Two new uracil (U) and 5-flurouracil (5-FU) labeled ruthenium(II)-polypyridyl based cellular imaging reagents are reported. Confocal laser scanning microscopic images with live and paraformaldehyde (PFA) fixed MCF-7 cells are examined using these two low-cytotoxic reagents. Experimental results show that these two complexes, appropriately functionalized with U (1) and 5-FU (2), have specific affinity for the lipid dense regions like the endoplasmic reticulum, cell membrane, and cytoplasmic vacuoles in live MCF-7 cells, and dye internalization in these regions happened following an endocytosis pathway. Interestingly, these two complexes are found to be localized in the nucleus of the PFA fixed cells. For fixed cells, presumably the lipid layer disruption helped in the explicit localization of the complexes 1 and 2 in the cell nucleus through specific interaction with cellular DNA. Poor and non-specific internalization of an analogous model complex 3, without having a U or 5-FU moiety, reveals the definite influence of U or 5-FU as well as the role of lipophilicity of the respective complex 1 and 2 in the cellular internalization process. Apart from these, a large Stokes shift (similar to 160 nm) and an appreciably long lived (MLCT)-M-3 excited state (similar to 320 ns) in aq. buffer medium (pH 7.4) are other key features for complexes 1 and 2. Unlike the common nuclear DNA staining reagents like DAPI, these low-cytotoxic reagents are found to be highly stable towards photo-bleaching upon irradiation with 455 nm at the MLCT band for these complexes.

1 aRamu, Vadde1 aAli, Firoj1 aTaye, Nandaraj1 aGarai, Bikash1 aAlam, Aftab1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/new-imaging-reagents-lipid-dense-regions-live-cells-and-nucleus-fixed-mcf-7-cells-001241nas a2200193 4500008004100000022001400041245011900055210006900174260011000243300001400353490000700367520044800374100002300822700001500845700001900860700002500879700001700904856012600921 2015 eng d a1359-734500aNew turn on Pd2+-specific fluorescence probe and its use as an imaging reagent for cellular uptake in Hct116 cells0 aNew turn on Pd2specific fluorescence probe and its use as an ima aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcJAN a3649-36520 v513 a

A new coumarin-rhodamine conjugate is used as a specific probe for Pd2+ ions and this could even delineate Pd(II) from Pd(0) or Pd(IV) in aqueous buffer medium (pH similar to 7). Laser confocal microscopic studies reveal that efficient cellular internalization of this reagent helps in imaging the cellular uptake of Pd2+ as low as 0.1 ppm in Hct 116 cells. This reagent could even be used for estimation of Pd2+ in human urine samples.

1 aReddy, Upendar, G.1 aAli, Firoj1 aTaye, Nandaraj1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/new-turn-pd2-specific-fluorescence-probe-and-its-use-imaging-reagent-cellular-uptake-001428nas a2200169 4500008004100000022001400041245005200055210005100107260011000158300001200268490000700280520081400287100002401101700002701125700001701152856008901169 2015 eng d a0306-001200aPhoto-responsive pseudorotaxanes and assemblies0 aPhotoresponsive pseudorotaxanes and assemblies aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcDEC a663-6760 v443 a

Chemists have achieved a predictable control over various non-covalent interactions and have used these weak interactions in their favour for developing a plethora of intricate functional structures. In this tutorial review we have summarized reports on such supramolecular structures that describe the rational approach in designing host and/or guest components, tagged with an appropriate fluorophore, for achieving the modified optical responses on formation of an assembly. This has relevance for designing new photo-responsive smart or adaptive stimuli responsive functional materials, self- healable materials, with interesting photo-physical property. These are also important in the area of supramolecular chemistry and biophysical chemistry in predicting the relative conformation in solution.

1 aMandal, Amal, Kumar1 aGangopadhyay, Monalisa1 aDas, Amitava uhttps://library.ncl.res.in/content/photo-responsive-pseudorotaxanes-and-assemblies-002501nas a2200193 4500008004100000022001400041245009100055210006900146260011000215300001600325490000700341520174100348100001802089700002202107700001702129700002702146700001702173856011702190 2015 eng d a1463-907600aRapid conductometric sensor for the analysis of cyanide using imidazole based receptor0 aRapid conductometric sensor for the analysis of cyanide using im aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcSEP a26790-267960 v173 a

A specific and efficient hydrogen bonding interaction between cyanide and the HN-H [imidazole] in an aqueous medium has been utilized for the selective recognition of cyanide under physiological conditions. The possibility of utilizing such an interaction for developing any practical device for the specific detection of cyanide in an aqueous environment has not been explored to date. We now report a simple dip and read conductometric sensor for cyanide ions using a tailored electrode in aqueous media. The purpose built reagent, 2-phenyl-1H-anthra-[2,3-d]-immidazole-5,10 dione was immobilized in a polyaniline matrix to fabricate this conductometric device. The homogeneous immobilization of the receptor in polyaniline was confirmed by FT-IR mapping. The proposed transduction mechanism is charge neutralization on the polyaniline moiety, which ultimately inhibits the protonation resulting in a decrease in the conductance of polyaniline. The sensor response was measured in three ranges of cyanide concentration (10(-10) M to 10(-8) M; 10(-8) M to 10(-6) M and 10(-6) M to 10(-3) M). Whereas the device is found insensitive in the first range, it acts as a detector in the second range and as a proportional sensor in the third range. The minimum detection limit of this device was found to be 10 nmol L-1 (2.6 ppt), which is significantly less than the WHO guideline values. The responses have been investigated under various conditions such as different pH and the electrochemical state of the polymer. The current device has been found to be better close to neutral pH and at a 400 mV vs. Ag/AgCl potential. The reproducibility and repeatability of the sensor was investigated and interference studies were performed.

1 aPaul, Anirban1 aPerween, Mosarrat1 aSaha, Sukdeb1 aSrivastava, Divesh, N.1 aDas, Amitava uhttps://library.ncl.res.in/content/rapid-conductometric-sensor-analysis-cyanide-using-imidazole-based-receptor-001209nas a2200205 4500008004100000022001400041245015300055210006900208260011000277300001600387490000700403520034900410100001800759700002300777700001500800700001900815700002500834700001700859856012700876 2015 eng d a1359-734500aReagent for specific recognition of cysteine in aqueous buffer and in natural milk: imaging studies, enzymatic reaction and analysis of whey protein0 aReagent for specific recognition of cysteine in aqueous buffer a aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcAUG a15592-155950 v513 a

We report a new chemodosimetric probe (L) for specific recognition of cysteine (Cys) in aqueous buffer and in whey protein isolated from fresh cow's milk. Using this reagent we could develop a luminescence-based methodology for estimation of Cys released from a commercially available Cys-supplement drug by aminoacylase-1 in live cells.

1 aAnila, H., A.1 aReddy, Upendar, G.1 aAli, Firoj1 aTaye, Nandaraj1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/reagent-specific-recognition-cysteine-aqueous-buffer-and-natural-milk-imaging-studies-002773nas a2200241 4500008004100000022001400041245011700055210006900172260007100241300001600312490000800328520190000336100001502236700001702251700001902268700001902287700002202306700001502328700002302343700002502366700001702391856012302408 2015 eng d a1520-610600aSpecific reagent for Cr(III): imaging cellular uptake of Cr(III) in Hct116 cells and theoretical rationalization0 aSpecific reagent for CrIII imaging cellular uptake of CrIII in H a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a13018-130260 v1193 a

A new rhodamine-based reagent (L-1), trapped inside the micellar structure of biologically benign Triton-X 100, could be used for specific recognition of Cr(III) in aqueous buffer medium having physiological pH. This visible light excitable reagent on selective binding to Cr(III) resulted in a strong fluorescence turn-on response with a maximum at similar to 583 nm and tail of that luminescence band extended until 650 nm, an optical response that is desired for avoiding the cellular autofluorescence. Interference studies confirm that other metal ions do not interfere with the detection process of Cr(III) in aqueous buffer medium having pH 7.2. To examine the nature of binding of Cr(III) to L-1, various spectroscopic studies are performed with the model reagent L-1 which tend to support Cr(III)-eta(2)-olefin pi-interactions involving two olefin bonds in molecular probe L-1. Computational studies are also performed with another model reagent L-M to examine the possibility of such Cr(III)-eta(2)-olefin pi-interactions. Presumably, polar functional groups of the model reagent L-M upon coordination to the Cr(III) center effectively reduce the formal charge on the metal ion and this is further substantiated by results of the theoretical studies. This assembly is found to be cell membrane permeable and shows insignificant toxicity toward live colon cancer cells (Hct116). Confocal laser scanning microscopic studies further revealed that the reagent L-1 could be used as an imaging reagent for detection of cellular uptake of Cr(III) in pure aqueous buffer medium by Hct116 cells. Examples of a specific reagent for paramagnetic Cr(III) with luminescence ON response are scanty in the contemporary literature. This ligand design helped us in achieving the turn on response by utilizing the conversion from spirolactam to an acyclic xanthene form on coordination to Cr(III).

1 aAli, Firoj1 aSaha, Sukdeb1 aMaity, Arunava1 aTaye, Nandaraj1 aSi, Mrinal, Kanti1 aSuresh, E.1 aGanguly, Bishwajit1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/specific-reagent-criii-imaging-cellular-uptake-criii-hct116-cells-and-theoretical-001122nas a2200193 4500008004100000022001400041245013800055210006900193260011000262300001400372490000700386520030900393100001900702700001500721700002300736700002500759700001700784856012700801 2015 eng d a1359-734500aTuning of multiple luminescence outputs and white-light emission from a single gelator molecule through an ESIPT coupled AIEE process0 aTuning of multiple luminescence outputs and whitelight emission  aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcDEC a2130-21330 v513 a

A unique example of an ESIPT coupled AIEE process, associated with a single molecule (1), is utilized for generating multiple luminescent colors (blue-green-white-yellow). The J-aggregated state of 1 forms a luminescent gel in THF and this luminescent property is retained even in the solid state.

1 aMaity, Arunava1 aAli, Firoj1 aAgarwalla, Hridesh1 aAnothumakkool, Bihag1 aDas, Amitava uhttps://library.ncl.res.in/content/tuning-multiple-luminescence-outputs-and-white-light-emission-single-gelator-molecule-002075nas a2200193 4500008004100000022001400041245019500055210006900250260007100319300001400390490000800404520123700412100002001649700001801669700002101687700001701708700002401725856013201749 2015 eng d a1932-744700aUltrafast electron injection, hole transfer, and charge recombination dynamics in cdse QD super-sensitized Re(I)-polypyridyl complexes with catechol and resorcinol moiety: effect of coupling0 aUltrafast electron injection hole transfer and charge recombinat a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcFEB a3522-35290 v1193 a

Ultrafast charge-transfer dynamics have been demonstrated in CdSe quantum dots (QD) using two Re(I)-polypyridyl complexes having pendent catechol (Re1,2) and resorcinol (Re1,3) as the sensitizer molecules. The energy level diagram of CdSe QD and Re1,2 and Re1,3 sensitizer reveals that photoexcited hole of CdSe QD can be transferred to both Re1,2 and Re1,3 molecule, and photoexcited Re1,2 and Re1,3 can inject electron in the conduction band, which has been confirmed by steady-state and time-resolved photoluminescence studies with selective photoexcitation. Femtosecond transient absorption studies have been carried out to monitor charge-transfer dynamics in early time scale. Transient absorption spectra show formation of cation radicals for both Re1,2 and Re1,3 in the 550-650 nm region with a peak at 590 nm region and broad absorption in the 650-1000 nm region, which can be attributed to photoexcited electron in the conduction band of CdSe QD. Charge recombination was determined by monitoring the decay of cation radicals as well as decay of an electron and found to be slower in the Re1,3/CdSe system as compared to that of the Re1,2/CdSe system, which is due to weaker electronic coupling in the former system.

1 aDebnath, Tushar1 aMaity, Partha1 aBanerjee, Tanmay1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/ultrafast-electron-injection-hole-transfer-and-charge-recombination-dynamics-cdse-qd-super-001870nas a2200169 4500008004100000245014400041210006900185260000800254300001400262490000700276520121600283100002701499700001901526700001601545700001701561856012201578 2016 eng d00a[2]Pseudorotaxane formation with fret based luminescence response: demonstration ofboolean operations through self sorting on solid surface0 a2Pseudorotaxane formation with fret based luminescence response  cOCT a8977-89870 v813 aBinary pseudorotaxane formation between an aza crown derivative as host (H) and two different imidazolium derivatives as guests (G(1) and G(2)) have been studied in detail by NMR (H-1 NMR, 2D NOESY), optical (steady state electronic and emission spectroscopy), and mass spectroscopy. Binding stoichiometry (1:1), association constant for the respective [2]pseudorotaxane formation (K-a(H center dot G1) = (2.61 +/- 0.015) X 10(3) M-1 and K-a(H center dot G2) = (1.27 +/- 0.16) X 10(3) M-1), and associated thermodynamic parameters are also evaluated based on isothermal titration calorimetric (ITC) studies. FRET based luminescence ON responses are observed on formation of the binary pseudorotaxane (H center dot G(1) and H center dot G(2)) in a nonpolar medium like dichlororriethane. The thermodynamic feasibility of such an energy transfer process is also examined. The higher affinity of H and 18-crown-6 toward K+, as compared to those toward G(1) or G(2), and the reversibility in the host- guest binding process are utilized in demonstrating the self-sorting phenomena with associated changes in luminescence responses that could be correlated for Boolean operators like YES, INHIBIT, OR, and AND gates.1 aGangopadhyay, Monalisa1 aMaity, Arunava1 aDey, Ananta1 aDas, Amitava uhttps://library.ncl.res.in/content/2pseudorotaxane-formation-fret-based-luminescence-response-demonstration-ofboolean02663nas a2200193 4500008004100000022001400041245013100055210006900186260007100255300001600326490000800342520188900350100001802239700002002257700002102277700001702298700002402315856013002339 2016 eng d a1932-744700aCharge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core-shell sensitized with Re(I)-polypyridyl complex0 aCharge delocalization in the cascade band structure CdSCdSe and  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAY a10051-100610 v1203 a

Charge-carrier dynamics of CdS quantum dot (QD) and CdS/CdSe type-I and CdS/CdTe type-II core shell nanocrystals (NCs) sensitized with a Re(I)-polypyridyl complex have been carried with special emphasis on studies on carrier delocalization and the role of Re-complex as a hole acceptor and sensitizer molecule. Our investigation confirmed photoexcited hole transfer from CdS and CdS/CdSe to the Re-complex, while no hole transfer was observed in the CdS/CdTe Re-complex system. This was rationalized by the evaluation of the relative energy levels, which revealed that such hole migration was not energetically favorable due to low-lying highest occupied molecular orbital (HOMO) of the Re-complex as compared with the valence band (VB) of CdTe shell; however, luminescence quenching from upper excited states of Re-complex was observed in the presence of all three QD and core shell systems, which has been attributed to electron injection from hot state (energetically higher than the LUMO state) of the Re-complex to the conduction band (CB) of the QDs. Transient absorption (lambda(pump) = 400 nm, lambda(probe) = 450-750 nm) spectra recorded for Re complex-sensitized CdS and CdS/CdSe composite in the femtosecond time domain revealed a broad transient absorption band in the 580-750 nm region with a peak around 595 nm, and this was attributed to the cation radical formation for Re-complex, either by capturing photoexcited hole from the NCs or by injecting electron to the CB of the NCs. As anticipated, no such spectrum was observed for the CdS/CdTe Re-complex composite system after 400 nm excitation. Electron injection from photoexcited Re-complex to CdS QD and CdS/CdSe core shell was found to be <100 fs, while the hole transfer from photoexcited CdS QD and CdS/CdSe core shell to Re-complex took place within the time scale of 900 fs and 2.5 ps, respectively.

1 aMaity, Partha1 aDebnath, Tushar1 aBanerjee, Tanmay1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/charge-delocalization-cascade-band-structure-cdscdse-and-cdscdte-core-shell-sensitized-rei01787nas a2200205 4500008004100000022001400041245012000055210006900175260000900244300001600253490000800269520105100277100001901328700002701347700001701374700001601391700003001407700001701437856012701454 2016 eng d a0002-786300aCounteranion driven homochiral assembly of a cationic C-3-symmetric gelator through ion-pair assisted hydrogen bond0 aCounteranion driven homochiral assembly of a cationic C3symmetri cSEP  a11113-111160 v1383 a

The helical handedness in achiral self-assemblies is mostly complex due to spontaneous symmetry breaking or kinetically controlled random assembly formation. Here an attempt has been made to address this issue through chiral anion exchange. A new class of cationic achiral C-3-symmetric gelator devoid of any conventional gelation assisting functional units is found to form both right-and left-handed helical structures. A chiral counteranion exchange-assisted approach is successfully introduced to control the chirality sign and thereby to obtain preferred homochiral assemblies. Formation of anion-assisted chiral assembly was confirmed by circular dichroism (CD) spectroscopy, microscopic images, and crystal structure. The X-ray crystal structure reveals the construction of helical assemblies with opposite handedness for (+)- and (-)-chiral anion reformed gelators. The appropriate counteranion driven ion-pair-assisted hydrogen-bonding interactions are found responsible for the helical bias control in this C-3-symmetric gelator.

1 aMaity, Arunava1 aGangopadhyay, Monalisa1 aBasu, Arghya1 aAute, Sunil1 aBabu, Sukumaran, Santhosh1 aDas, Amitava uhttps://library.ncl.res.in/content/counteranion-driven-homochiral-assembly-cationic-c-3-symmetric-gelator-through-ion-pair00686nas a2200181 4500008004100000245012500041210006900166260000800235300001600243490000700259100001800266700001500284700002100299700001900320700002500339700001700364856012300381 2016 eng d00aCysteine-specific fluorescent switch for monitoring oxidative stress and quantification of aminoacylase-1 in blood serum0 aCysteinespecific fluorescent switch for monitoring oxidative str cDEC a12161-121680 v881 aAnila, H., A.1 aAli, Firoj1 aKushwaha, Shilpi1 aTaye, Nandaraj1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/cysteine-specific-fluorescent-switch-monitoring-oxidative-stress-and-quantification02185nas a2200241 4500008004100000022001400041245015900055210006900214260005700283300000800340490000700348520129500355653000801650653003101658653001701689653002001706653001101726100002401737700002001761700001701781700002301798856012201821 2016 eng d a1610-294000aDoes the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study0 aDoes the position of the electrondonating nitrogen atom in the r a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGERcJUN a1210 v223 a

We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as pi-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and pi-conjugation on solar cell performance. The calculated electron-injection driving force (Delta G(inject)), electron-regeneration driving force (Delta G(regen)), light-harvesting efficiency (LHE), dipole moment (mu(normal)), and number of electrons transferred (Delta q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system.

10aDFT10aDye-sensitized solar cells10aOrganic dyes10aPosition effect10aTD-DFT1 aBiswas, Abul, Kalam1 aBarik, Sunirmal1 aDas, Amitava1 aGanguly, Bishwajit uhttps://library.ncl.res.in/content/does-position-electron-donating-nitrogen-atom-ring-system-influence-efficiency-dye01412nas a2200217 4500008004100000245008700041210006900128260000800197300001400205490000600219520069900225100002300924700001500947700001800962700002100980700001701001700001801018700002701036700001701063856011401080 2016 eng d00aFluorescent probe for bisulfite ions: its application to two-photon tissue imaging0 aFluorescent probe for bisulfite ions its application to twophoto cDEC a7888-78940 v43 aA benzoxazinone based fluorescent probe for the specific and efficient detection of bisulfite ions in aqueous medium is described. The probe formed a bisulfite/sulphite adduct with an associated turn-on fluorescence response in the red wavelength region. No interference was observed in the detection process from all possible competing anions and molecules, including cyanide ion, cysteine, homocysteine and glutathione. In addition, the probe showed a fast response time, low detection limit, and cell membrane permeability. Furthermore, the probe was two-photon excitable, enabling imaging of endogenous bisulfite ions in HeLa cells as well as in deep tissues from different organs of mouse.1 aAgarwalla, Hridesh1 aPal, Suman1 aPaul, Anirban1 aJun, Yong, Woong1 aBae, Juryang1 aAhn, Kyo, Han1 aSrivastava, Divesh, N.1 aDas, Amitava uhttps://library.ncl.res.in/content/fluorescent-probe-bisulfite-ions-its-application-two-photon-tissue-imaging03045nas a2200229 4500008004100000245017800041210006900219260000800288300001400296490000700310520219500317100001502512700001602527700001902543700002302562700002102585700001902606700002102625700002502646700001702671856012702688 2016 eng d00aGSH Induced controlled release of levofloxacin from a purpose-built prodrug: luminescence response for probing the drug release in escherichia coli and staphylococcus aureus0 aGSH Induced controlled release of levofloxacin from a purposebui cSEP a2062-20700 v273 a

Fluoroquinolones are third-generation broad spectrum bactericidal antibiotics and work against both Gram-positive and Gram-negative bacteria. Levofloxacin (L), a fluoroquinolone, is widely used in anti-infective chemotherapy and treatment of urinary tract infection and pneumonia. The main pathogen for urinary tract infections is Escherichia colt, and Streptococcus pneumoniae is responsible for pneumonia, predominantly a lower respiratory tract infection. Poor permeability of L leads to the use of higher dose of this drug and excess drug in the outer cellular fluid leads to central nervous system (CNS) abnormality. One way to counter this is to improve the lipophilicity of the drug molecule, and accordingly, we have synthesized two new Levofloxacin derivatives, which participated in the spatiotemporal release of drug via disulfide bond cleavage induced by glutathione (GSH). Recent studies with Streptococcus mutants suggest that it is localized in epithelial lining fluid (ELF) of the normal lower respiratory tract and the effective [GSH] in ELF is similar to 430 mu M. E. coli typically cause urinary tract infections and the concentration of GSH in porcine bladder epithelium is reported as 0.6 mM for a healthy human. Thus, for the present study we have chosen two important bacteria (Gram + ve and Gram - ve), which are operational in regions having high extracellular GSH concentration. Interestingly, this supports our design of new lipophilic Levofloxacin based prodrugs, which released effective drug on reaction with GSH. Higher lipophilicity favored improved uptake of the prodrugs. Site specific release of the drug (L) could be achieved following a glutathione mediated biochemical transformation process through cleavage of a disulfide bond of these purpose-built prodrugs. Further, appropriate design helped us to demonstrate that it is possible also to control the kinetics of the drug release from respective prodrugs. Associated luminescence enhancement helps in probing the release of the drug from the prodrug in bacteria and helps in elucidating the mechanistic pathway of the transformation. Such an example is scarce in the contemporary literature.

1 aPal, Suman1 aRamu, Vadde1 aTaye, Nandaraj1 aMogare, Devraj, G.1 aYeware, Amar, M.1 aSarkar, Dhiman1 aReddy, Srinivasa1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/gsh-induced-controlled-release-levofloxacin-purpose-built-prodrug-luminescence-response01603nas a2200169 4500008004100000245008200041210006900123260000800192300001600200490000800216520102100224100001901245700001601264700001701280700002401297856011201321 2016 eng d00aProton-coupled electron transfer in a hydrogen-bonded charge transfer complex0 aProtoncoupled electron transfer in a hydrogenbonded charge trans cOCT a10780-107850 v1203 aA proton-coupled electron transfer (PCET) reaction in a hydrogen bonded charge-transfer (CT) complex of 4-([2,2'-bipyridin]-4-yl)phenol (bpy-phenol) with a F- ion has been investigated by ultrafast time-resolved transient absorption spectroscopy. The phenolic receptor molecule, bpy-phenol, binds to the F- ion through a hydrogen bond and senses the F- ion-via the Stokes-shifted CT band. Upon photoexcitation, CT from the phenol residue to the bpy residue promotes proton transfer from the phenol radical cation (ArOH center dot+) to the fluoride ion at ultrafast time scales of <150 fs (instrument response function limited) and 3 ps, separately. The fast and slow proton-transfer times are linked to two different types of hydrogen-bonding networks between the phenol residue and fluoride ion. Crystalline water in the fluoride salt hydrates mediates the proton-transfer reaction. This work demonstrates the participation of a hydrogen-bonded water bridge within a PCET reaction in a water restricted environment.1 aVerma, Sandeep1 aAute, Sunil1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/proton-coupled-electron-transfer-hydrogen-bonded-charge-transfer-complex01330nas a2200205 4500008004100000022001400041245012700055210006900182260011000251300001400361490000700375520049600382100001500878700001800893700001900911700002300930700002500953700001700978856012900995 2016 eng d a1359-734500aSpecific receptor for hydrazine: mapping the in situ release of hydrazine in live cells and in an in vitro enzymatic assay0 aSpecific receptor for hydrazine mapping the in situ release of h aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAR a6166-61690 v523 a

We report a new chemodosimetric reagent capable of detecting hydrazine in the presence of several other competing amine derivatives and ionic analytes of biological relevance. This reagent has been utilized for real time monitoring of in situ N2H4 release during the metabolism of a crucial tuberculosis drug, isoniazid, in live HepG2 cells. The fluorescence response of the reagent based on its specific reaction with N2H4 is used for developing an in vitro assay for aminoacylase-1.

1 aAli, Firoj1 aAnila, H., A.1 aTaye, Nandaraj1 aMogare, Devraj, G.1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/specific-receptor-hydrazine-mapping-situ-release-hydrazine-live-cells-and-vitro-enzymatic02218nas a2200217 4500008004100000245009700041210006900138260000800207300001600215490000700231520147200238100002401710700002401734700001901758700001901777700002301796700002401819700002501843700001701868856011501885 2016 eng d00aSwitch-on NIR probe for specific detection of Hg2+ ion in aqueous medium and in mitochondria0 aSwitchon NIR probe for specific detection of Hg2 ion in aqueous  cNOV a12052-120600 v553 aA new 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY)-based probe molecule (L) is synthesized for specific binding to Hg2+ ion in physiological condition with an associated luminescence ON response in the near-IR region of the spectrum. Appropriate functionalization in the 5-position of each of two pyrrole moieties with styryl functionality in a BODIPY core helped us in achieving the extended conjugation and a facile intramolecular charge transfer transition with a narrow energy gap for frontier orbitals. This accounted for a poor emission quantum yield for the probe molecule L. Binding to. Hg2+ helped in interrupting the facile intramolecular charge transfer (ICT) process that was initially operational for L. This resulted in a hypsochromic shift of absorption band and a turn-on luminescence response with lambda(Em)(max) of 650 nm on specific binding to Hg2+. Observed spectral changes are rationalized based on quantum chemical calculations. Interestingly, this reagent is found to be localized preferentially in the mitochondria of the live human colon cancer (Hct116) cells. Mitochondria is one of the major targets for localization of He2+, which actually decreases the mitochondrial membrane potential and modifies various proteins having sulfudryl functionality(ies) to cause cell apoptosis. Considering these, ability of the present reagent to specifically recognize Hg2+] in the mitochondrial region of the live Hct116 cells has significance.1 aAgarwalla, Hrideshg1 aMahajan, Pankaj, S.1 aSahu, Debashis1 aTaye, Nandaraj1 aGanguly, Bishwajit1 aMhaske, Santosh, B.1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/switch-nir-probe-specific-detection-hg2-ion-aqueous-medium-and-mitochondria02225nas a2200205 4500008004100000022001400041245012900055210006900184260007100253300001200324490000700336520140500343100002701748700002101775700001901796700002601815700003501841700001701876856012601893 2016 eng d a0022-326300aTuning emission responses of a triphenylamine derivative in host-guest complexes and an unusual dynamic inclusion phenomenon0 aTuning emission responses of a triphenylamine derivative in host a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJAN a512-5210 v813 a

A newly synthesized triphenylamine derivative (1Cl(3)) shows significant differences in inclusion complex formation with two different macrocyclic hosts, cucurbit[7]uril (CB[7]) and beta-cyclodextrin (beta-CD). Detailed investigations by NMR spectroscopy reveal that CB[7] forms a 1:3 host-guest complex ([1 center dot 3{CB[7]}]Cl-3) in which three arms of 1Cl(3) are bound to three host molecules. On the other hand, beta-CD forms a dynamic 1:1 inclusion complex ([1 center dot{beta-CD}]Cl-3) by binding to only one of the three arms of 1Cl(3) at a given time. The formation of a 1:1 host-guest complex with beta-CD and 1:3 host-guest complex with CB[7] was also confirmed from the results of the isothermal titration calorimetric studies. Interestingly, 1Cl(3) exhibits a rare dual emission property in solution at room temperature with the lower and higher energy bands arising from a locally excited state and an intramolecular charge-transfer transition, respectively. The difference in inclusion complex formation behavior of 1Cl(3) with the two macrocyclic hosts results in the stabilization of different emission states in the two inclusion complexes. The fundamental difference in the electrostatic surface potentials, cavity polarities, and shapes of the two macrocyclic hosts could account for the formation of the different inclusion complexes with distinct luminescence responses.

1 aGangopadhyay, Monalisa1 aMandal, Amal, K.1 aMaity, Arunava1 aRavindranathan, Sapna1 aRajamohanan, Pattuparambil, R.1 aDas, Amitava uhttps://library.ncl.res.in/content/tuning-emission-responses-triphenylamine-derivative-host-guest-complexes-and-unusual-102566nas a2200193 4500008004100000245013000041210006900171260000800240300001600248490000700264520184300271100002702114700001902141700001602160700002402176700002602200700001702226856012902243 2017 eng d00aChiral discrimination through h-1 nmr and luminescence spectroscopy: dynamic processes and solid strip for chiral recognition0 aChiral discrimination through h1 nmr and luminescence spectrosco cDEC a18303-183130 v233 aThe appropriate choice of the host molecules with well-defined optical activity (S-H/R-H) helps in the differentiation between two secondary ammonium ion-derivative guest molecules with different optical activities (R-G/S-G) based on the fluorescence resonance energy transfer (FRET)based luminescence responses. Crown ether-based host molecules with opposite chiral configurations (R-H, S-H) have been derived from 1,1'-bi-2-naphthol (BINOL) derivatives that have axially chiral biaryl centers. These chiral crown ethers form host-guest complexes (i.e., [2] pseudoro-taxanes) with chiral secondary ammonium ion derivatives (R-G, S-G). NMR spectroscopic studies show that the complexes are in a dynamic equilibrium in solution. Results of the H-1 NMR and fluorescence spectroscopic studies indicate a head-on orientation of the host and guest in the [2] pseudorotaxanes. The difference in the efficiency in the FRET-based responses between anthracene and the BINOL derivatives allow efficient chiral discrimination of the guests. Isothermal titration calorimetry and NMR investigations reveal that inclusion complexes between hosts and guests of the same chirality (R-H center dot R-G, S-H center dot S-G) are more stable relative to those of opposite chirality (R-H center dot S-G, S-H center dot R-G). However, FRET-based energy-transfer efficiency is higher for R-H center dot S-G and S-H center dot R-G complexes. NMR spectroscopic studies show that the relative orientation of the guest in the host cavity is significantly different when the host binds a guest of the same or opposite chirality; furthermore, the latter is more favorable for FRET, thus enabling discrimination between enantiomers. Interestingly, chiral discrimination of guest ions could also be achieved by using silica surfaces modified with chiral host molecules.1 aGangopadhyay, Monalisa1 aMaity, Arunava1 aDey, Ananta1 aRajamohanan, P., R.1 aRavindranathan, Sapna1 aDas, Amitava uhttps://library.ncl.res.in/content/chiral-discrimination-through-h-1-nmr-and-luminescence-spectroscopy-dynamic-processes-and01921nas a2200193 4500008004100000245008100041210006900122260000800191300001600199490000700215520124900222100002101471700001901492700002701511700002601538700003501564700001701599856011101616 2017 eng d00aCucurbit[7]uril induced formation of fret-enabled unilamellar lipid vesicles0 aCucurbit7uril induced formation of fretenabled unilamellar lipid cOCT a10989-109990 v333 aA unique fluorescence resonance energy transfer (FRET) process is found to be operational in a unilamellar lipid self-assembly in the aqueous phase. A newly synthesized naphthyl based long chain lipid derivative [N-(naphthalene-1-ylmethyl)tetradecane-1-ammonium chloride, 14NA(+)] forms various self-assembled architectures in the aqueous phase. Controlled changes in lipid concentration lead to a transition of the self-assemblies from micelles to vesicles to rods. In the presence of cucurbit[7]uril (CB7), 14NA(+) forms a host-guest [2]pseudorotaxane complex (CB7(sic)14NA(+)) and secondary interactions lead to the formation of a lipid bilayer with hydrophobic pockets situated in between the layers. The change in the structure of 14NA(+) assemblies, interaction with CB7 and formation of supramolecular assemblies of CB7(sic)14NA(+) were examined using light scattering, spectroscopic, and microscopic techniques. Entrapment of a luminescent dye, anthracene within the hydrophobic bilayer of the supramolecular assembly CB7(sic)14NA(+) favors a modified luminescent response due to an efficient FRET process. Further, the FRET process could be controlled by thermal and chemical stimuli that induce transformation of unilamellar vesicles.1 aKushwaha, Shilpi1 aMaity, Arunava1 aGangopadhyay, Monalisa1 aRavindranathan, Sapna1 aRajamohanan, Pattuparambil, R.1 aDas, Amitava uhttps://library.ncl.res.in/content/cucurbit7uril-induced-formation-fret-enabled-unilamellar-lipid-vesicles01821nas a2200157 4500008004100000245015300041210006900194260000800263490000700271520118300278100002401461700001701485700001601502700001801518856012701536 2017 eng d00aDemonstrating the role of anchoring functionality in interfacial electron transfer dynamics in newly synthesized BODIPY-TiO2 nanostructure composite0 aDemonstrating the role of anchoring functionality in interfacial cMAY0 v413 aNew Bodipy derivatives (Dye 1 and 2) having catechol or resorcinol functionality for anchoring to the nanostructured (NS) TiO2 surfaces have been synthesized. Extended conjugation at one of the two pyrrole rings at the C3 position has helped us in achieving the desired control in tuning the optical and redox properties of the BODIPY based dye molecules. Relative emission quantum yields (em1 = ~52 ± 2% and em2 = 54 ± 2%) are found to be much higher in polar aprotic solvent (acetonitrile), while this are found to be substantially lower for dye 1 in polar protic solvent. Steady state optical absorption studies reveal the formation of a strong charge transfer complex between dye 1 and NS-TiO2, while this interaction is much weaker for dye 2. Transient absorption studies have been carried out for 1/NS-TiO2 and 2/NS-TiO2 systems following excitation with a laser source of 400 nm for understanding the charge transfer dynamics. Results of the transient absorption spectral studies helped in elucidating role of anchoring functionality in influencing the dynamics of the interfacial electron transfer and the charge recombination process in ultrafast time scale.1 aGhosh, Hirendra, N.1 aDas, Amitava1 aAute, Sunil1 aMaity, Partha uhttps://library.ncl.res.in/content/demonstrating-role-anchoring-functionality-interfacial-electron-transfer-dynamics-newly02261nas a2200241 4500008004100000245014200041210006900183260000800252300001400260490000700274520140700281100001601688700001601704700001901720700002201739700002401761700002001785700002301805700002001828700002501848700001701873856012901890 2017 eng d00aPhoto-induced cytotoxicity and anti-metastatic activity of ruthenium(II)-polypyridyl complexes functionalized with tyrosine or tryptophan0 aPhotoinduced cytotoxicity and antimetastatic activity of rutheni cMAY a6634-66440 v463 aThe synergistic effect of oxygen, light, and photosensitizer (PS) has found applications in medicine for the treatment of cancer through photodynamic therapy (PDT). Induction of apoptosis to cancerous cells will prevent tumor metastasis that spreads cancer cells to the neighboring organs/tissues. Herein, we report the two apoptotic Ru(II)-polypyridyl complexes that are functionalized with pendant amino acid moieties tyrosine (1) and tryptophan (2), respectively. These two water soluble complexes were found to interact strongly (K-a(1) = (1.18 +/- 0.28) x 10(5) M-1 and K-a(2) = (1.57 +/- 0.77) x 10(5) M-1) with CT-DNA. Isothermal titration calorimetry (ITC) studies revealed that these complexes bind to CT-DNA through an entropically driven process. Both the complexes showed photo-induced cytotoxicity and exhibit apoptotic activity under photo-irradiation conditions. The comet assay indicated that these complexes can damage cellular DNA, which is attributed to the significant build-up of O-1(2) level even on irradiation with low intensity light (10 J cm(-2), lambda(Range) 450-480 nm). This photoinduced DNA damage and apoptosis in A549 cells was induced by reactive oxygen species (ROS) and occurred through up-regulation of apoptotic marker caspase-3. Control experiments under dark conditions revealed an insignificant cytotoxicity towards these cells for two photosensitive molecules.1 aRamu, Vadde1 aAute, Sunil1 aTaye, Nandaraj1 aGuha, Rweetuparna1 aWalker, Michael, G.1 aMogare, Devaraj1 aParulekar, Apoorva1 aThomas, Jim, A.1 aChattopadhyay, Samit1 aDas, Amitava uhttps://library.ncl.res.in/content/photo-induced-cytotoxicity-and-anti-metastatic-activity-rutheniumii-polypyridyl-complexes02146nas a2200193 4500008004100000245015900041210006900200260000800269300001400277490000700291520141500298100001601713700001801729700001601747700001801763700001701781700002401798856013001822 2017 eng d00aProton-coupled electron-transfer processes in ultrafast time domain: evidence for effects of hydrogen-bond stabilization on photoinduced electron transfer0 aProtoncoupled electrontransfer processes in ultrafast time domai cMAR a3455-34650 v233 aThe proton-coupled electron-transfer (PCET) reaction is investigated for a newly synthesized imidazoleanthraquinone biomimetic model with a photoactive RuIIpolypyridyl moiety that is covalently coupled to the imidazole fragment. Intramolecular H-bonding interactions between imidazole and anthraquinone moieties favor the PCET process; this can be correlated to an appreciable positive shift in the one-electron reduction potential of the coordinated anthraquinone moiety functionalized with the imidazole fragment. This can also be attributed to the low luminescence quantum yield of the RuII-polypyridyl complex used. The dynamics of the intramolecular electron-transfer (ET) and PCET processes are studied by using femtosecond transient absorption spectroscopy. The steady- state spectroscopic studies and the results of the time- resolved absorption studies confirm that H- bonded water molecules play a major role in both ET and PCET dynamics as a proton relay in the excited state. The electron- transfer process is followed by a change in the H- bonding equilibrium between AQ and imidazole in acetonitrile solvent, and protonation of AQ(-) water leads to PCET in the presence of water. A slower forward and backward electron- transfer rate is observed in the presence of D2O compared with that in H2O. These results provide further experimental support for a detailed understanding of the PCET process.1 aDey, Ananta1 aDana, Jayanta1 aAute, Sunil1 aMaity, Partha1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/proton-coupled-electron-transfer-processes-ultrafast-time-domain-evidence-effects-hydrogen01610nas a2200193 4500008004100000022001400041245008600055210006900141260000900210300001400219490000700233520095900240100002401199700001601223700003001239700001701269700002001286856011001306 2017 eng d a1477-922600aRatiometric sensor for DNA based on a dual emission Ru(dppz) light-switch complex0 aRatiometric sensor for DNA based on a dual emission Rudppz light cMAY  a6079-60860 v463 a

Herein we describe the DNA binding properties of two new water-soluble ruthenium complexes; experimental and computational data reveal that both complexes display dual emission from MLCT and LLCT excited states. The interaction of the new complexes with DNA was also investigated. Although one of the complexes only binds DNA though groove binding, the second complex has separate ligands capable of groove binding and intercalation. Nevertheless, it was found that both complexes interact with duplex DNA with high affinity. DNA induced distinctive changes in the emission of the complexes; although the groove binding complex only displays a modest increase in emission on binding, the complex that contains the intercalating Ru-II(dppz) moiety displays a large increase in MLCT-based emission on DNA binding while emission from the LLCT excited state is unaffected. This means that the complex functions as the first ratiometric sensor for DNA.

1 aWalker, Michael, G.1 aRamu, Vadde1 aMeijer, Anthony, J. H. M.1 aDas, Amitava1 aThomas, Jim, A. uhttps://library.ncl.res.in/content/ratiometric-sensor-dna-based-dual-emission-rudppz-light-switch-complex01412nas a2200205 4500008004100000245008700041210006900128260000800197300001600205490000700221520072100228100001500949700002500964700002700989700002001016700002401036700002001060700001701080856010901097 2017 eng d00aSuper-resolution probe to monitor HNO levels in the endoplasmic reticulum of cells0 aSuperresolution probe to monitor HNO levels in the endoplasmic r cNOV a12087-120930 v893 aSelective detection of nitroxyl (HNO), which has recently been identified as a reactive nitrogen species, is a challenging task. We report a BODIPY-based luminescence ON reagent for detection of HNO in aqueous solution and in live RAW 264.7 cells, based on the soft nucleophilicity of the phosphine oxide functionality toward HNO. The probe shows high selectivity to HNO over other reactive oxygen/nitrogen and sulfur species. Luminescence properties of the BODIPY-based chemodosimetric reagent make it an ideal candidate for use as a reagent for super-resolution structured illumination microscopy. The viability of the reagent for biological in vivo imaging application was also confirmed using Artemia as a model.1 aAli, Firoj1 aSreedharan, Sreejesh1 aAshoka, Anila, Hoskere1 aSaeed, Hiwa, K.1 aSmythe, Carl, G. W.1 aThomas, Jim, A.1 aDas, Amitava uhttps://library.ncl.res.in/content/super-resolution-probe-monitor-hno-levels-endoplasmic-reticulum-cells00951nas a2200205 4500008004100000245014100041210006900182260000800251300001400259490000700273520017900280100002300459700002300482700001500505700002800520700002300548700002700571700001700598856013000615 2018 eng d00aFluorescent chemodosimeter for quantification of Cystathionine-y-synthase activity in plant extracts and imaging of endogenous biothiols0 aFluorescent chemodosimeter for quantification of Cystathionineys cAUG a9079-90820 v543 a

A new reagent for quantification of CgS in plant extracts using a generalized methodology suitable for recognition of homocysteine (Hcy) with luminescence ON response.

1 aAgarwalla, Hridesh1 aHoskere, Anila, A.1 aAli, Firoj1 aPradhan, Swaraj, Rashmi1 aGanguly, Bishwajit1 aPramanik, Sumit, kumar1 aDas, Amitava uhttps://library.ncl.res.in/content/fluorescent-chemodosimeter-quantification-cystathionine-y-synthase-activity-plant-extracts01580nas a2200193 4500008004100000022001400041245019600055210006900251260000800320300001400328490000700342520081000349100001901159700001601178700002201194700002301216700001701239856013001256 2018 eng d a1744-683X00aImpact of half-crown/two carbonyl:-Ca2+ metal ion interactions of a low molecular weight gelator (LMWG) on its fiber to nanosphere morphology transformation with a gel-to-sol phase transition0 aImpact of halfcrowntwo carbonylCa2 metal ion interactions of a l cJUL a5821-58310 v143 a

We report here a smart functional low molecular weight gelator (LMWG) L, containing an unusual metal ion coordination site, i.e. ``half-crown/two carbonyl''. The gelator L shows excellent gelation behavior with typical fibrillar morphology in acetonitrile, methanol and ethanol media. Upon Ca2+ ion binding with its ``half-crown/two carbonyl'' coordination site, the acetonitrile gel of L exhibits a fiber to nanosphere morphology transformation along with a gel-to-sol phase transition as confirmed by microscopic investigation and by direct naked eye visualization, respectively. The mechanism involved in this morphology transformation and gel-to-sol phase transition process was studied thoroughly with the help of computational calculations and various spectroscopic experiments and discussed.

1 aMaity, Arunava1 aDey, Ananta1 aSi, Mrinal, Kanti1 aGanguly, Bishwajit1 aDas, Amitava uhttps://library.ncl.res.in/content/impact-half-crowntwo-carbonyl-ca2-metal-ion-interactions-low-molecular-weight-gelator-lmwg01099nas a2200205 4500008004100000022001400041245011600055210006900171260000800240300001400248490000700262520037900269100002300648700002500671700001500696700002100711700002000732700001700752856012400769 2018 eng d a1359-734500aPolysulfide-triggered fluorescent indicator suitable for super-resolution microscopy and application in imaging0 aPolysulfidetriggered fluorescent indicator suitable for superres cAPR a3735-37380 v543 a

A new physiologically benign and cell membrane permeable BODIPY based molecular probe, MB-S-n, specifically senses intracellular hydrogen polysulfides (H2Sn, n > 1) localized in the endoplasmic reticulum. This reagent is suitable for mapping the intracellular distribution of H2Sn by wide-field as well as super-resolution Structured Illumination Microscopy (SIM).

1 aHoskere, Anila, A.1 aSreedharan, Sreejesh1 aAli, Firoj1 aSmythe, Carl, G.1 aThomas, Jim, A.1 aDas, Amitava uhttps://library.ncl.res.in/content/polysulfide-triggered-fluorescent-indicator-suitable-super-resolution-microscopy-and01189nas a2200229 4500008004100000022001400041245011500055210006900170260000800239300001400247490000700261520041100268100001500679700001600694700002500710700001800735700002000753700002100773700002000794700001700814856012800831 2018 eng d a1359-734500aTracking HOCl concentrations across cellular organelles in real time using a super resolution microscopy probe0 aTracking HOCl concentrations across cellular organelles in real  cFEB a1849-18520 v543 a

BODIPY derivative, SF-1, exclusively shows a fluorescence ON response to HOCl and images endogenously generated HOCl in RAW 264.7 macrophages. Widefield and super resolution structured illumination microscopy images confirm localization in the Golgi complex and lysosomes, and hence specifically detects HOCl generated in these organelles. SF-1 is compatible with 3D-SIM imaging of individual cells.

1 aAli, Firoj1 aAute, Sunil1 aSreedharan, Sreejesh1 aAnila, H., A.1 aSaeed, Hiwa, K.1 aSmythe, Carl, G.1 aThomas, Jim, A.1 aDas, Amitava uhttps://library.ncl.res.in/content/tracking-hocl-concentrations-across-cellular-organelles-real-time-using-super-resolution02016nas a2200181 4500008004100000022001400041245015300055210006900208260000800277300001400285490000700299520131800306100001901624700001601643700002701659700001701686856013101703 2018 eng d a2040-336400aWater induced morphological transformation of a poly(aryl ether) dendron amphiphile: helical fibers to nanorods, as light-harvesting antenna systems0 aWater induced morphological transformation of a polyaryl ether d cJAN a1464-14730 v103 a

Self-assembly of suitable molecular building blocks is an efficient and convenient approach to generate nanomaterials with various morphologies and functions. Moreover, understanding the nature of molecules and controlling factors of their self-assembly process is crucial in fundamental aspects of molecular self-assembly which provide insights into the design of new assemblies with functional nano-architectures. To this end, the present study reports water induced self-assembled multifaceted morphology formation and the plausible pathway of the morphology transformation of a single poly(aryl ether) dendron amphiphile 1(D). In THF, 1(D) self-assembles into helical fibers. However, with an increase in the water fraction in its THF solution, the morphology changes to nanorods through an intermediate scroll-up pathway of exfoliated fibers. The nanorod formation and transformation of 1(D) are investigated using various microscopy and spectroscopy techniques, which indicate that it has highly ordered multilayered arrays of 1(D) molecules. Finally, these multilayered arrays of 1(D) nanorods are exploited for constructing a model light-harvesting system via the incorporation of small quantities of two newly designed BODIPY based molecules as energy acceptors and 1(D) as an antenna chromophore.

1 aMaity, Arunava1 aDey, Ananta1 aGangopadhyay, Monalisa1 aDas, Amitava uhttps://library.ncl.res.in/content/water-induced-morphological-transformation-polyaryl-ether-dendron-amphiphile-helical-fibers00959nas a2200193 4500008004100000022001400041245006200055210006200117260000900179300001400188490000700202520035000209100002500559700002700584700001900611700001700630700002700647856009100674 2019 eng d a1359-734500aFluorogenic BODIPY molecular rotor as an apoptosis marker0 aFluorogenic BODIPY molecular rotor as an apoptosis marker cJUN  a6902-69050 v553 a

Based on a BODIPY molecular rotor and a zinc-dipicolylamine receptor, we designed a fluorogenic probe for the detection of apoptosis. Being poorly emissive in solution and with healthy cells, it selectively binds phosphatidylserine of early apoptotic cells and internalizes into late apoptotic cells, lighting up its green fluorescence.

1 aAshokkumar, Pichandi1 aAshoka, Anila, Hoskere1 aCollot, Mayeul1 aDas, Amitava1 aKlymchenko, Andrey, S. uhttps://library.ncl.res.in/content/fluorogenic-bodipy-molecular-rotor-apoptosis-marker03024nas a2200193 4500008004100000022001400041245017500055210006900230260000900299300001400308490000700322520228300329100001602612700001802628700001602646700001702662700002402679856012702703 2019 eng d a1474-905X00aHydrogen bond assisted photoinduced intramolecular electron transfer and proton coupled electron transfer in an ultrafast time domain using a ruthenium-anthraquinone dyad0 aHydrogen bond assisted photoinduced intramolecular electron tran cOCT  a2430-24410 v183 a

Quinones play a significant role as primary electron acceptors in the natural photosynthetic system of photosystem II, and their reduction is known to be facilitated by hydrogen-bond donors or protonation. In this study, a ruthenium(ii) polypyridyl complex 1 coupled to an anthraquinone (AQ) functionality through a rigid imidazole (Im) spacer has been synthesized to examine the effect of H-bonding on both the thermal and photoinduced electron transfer reactions. The anthraquinone moiety of complex 1 is fused to a benzi-imidazole system bearing C & xe001;(OMIDLINE)-M-AQ HORIZONTAL ELLIPSISHNIm based H-bonding at one side of the anthraquinone moiety so that intramolecular hydrogen bonding from the imidazole group to the nearby quinone carbonyl can occur. The hydrogen bond formation involving the semiquinone radical anion produced through the photoinduced reduction process in Ru-im-AQ and the imidazole proton in complex 1 resulted in a significant positive shift of one electron reduction potential of complex 1. The kinetics for the formation of the charge-separated states was explored by using femtosecond transient absorption spectroscopy. Hydrogen bonding between water and the reduced anthraquinone accounted for thermodynamic and kinetic stabilization of these charge-separated states. An attempt has been made to assess the relative importance of the driving force and solvent polarity, in the rates of photoinduced electron transfer in complex 1. The 490 nm transient absorption band of anthraquinone radical anions (AQ(-)) and a broad absorption in the 580-750 nm region having maxima at similar to 690 nm have been observed and this is attributed to the generation of a transient Ru3+-species of the corresponding complex 1. Addition of water entails an acceleration of electron transfer rates by a factor of 3.33. The system investigated may serve as a model for the mechanistic diversity of PCET reactions in general with water as a primary proton donor. Furthermore, our studies are relevant for understanding proton-coupled electron transfer (PCET) reactivity of electronically excited states at a fundamental level because changes in hydrogen-bonding strength accompanying changes in redox states may be regarded as a variant form of PCET.

1 aDey, Ananta1 aDana, Jayanta1 aAute, Sunil1 aDas, Amitava1 aGhosh, Hirendra, N. uhttps://library.ncl.res.in/content/hydrogen-bond-assisted-photoinduced-intramolecular-electron-transfer-and-proton-coupled02838nas a2200253 4500008004100000022001400041245013200055210006900187260000800256300001400264490000600278520194300284653003702227653002602264653002802290653002002318653001202338653002902350100002102379700001602400700002602416700001702442856012502459 2020 eng d a2379-369400aPolymer nanorings with uranium specific clefts for selective recovery of uranium from acidic effluents via reductive adsorption0 aPolymer nanorings with uranium specific clefts for selective rec cOCT a3254-32630 v53 a

Nanostructured polymeric materials, functionalized with an appropriate receptor, have opened up newer possibilities for designing a reagent that shows analyte-specific recognition and efficient scavenging of an analyte that has either a detrimental influence on human physiology and environment or on its recovery for further value addition. Higher active surface area, morphological diversity, synthetic tunability for desired surface functionalization, and the ease of regeneration of a nanostructured material for further use have provided such materials with a distinct edge over conventional reagents. The use of a biodegradable polymeric backbone has an added significance owing to the recent concern over the impact of polymers on the environment. Functionalization of biodegradable sodium alginate with AENA (6.85% grafting) as the receptor functionality led to a unique open framework nanoring (NNRG) morphology with a favorable spatial orientation for specific recognition and efficient binding to uranyl ions (U) in an aqueous medium over a varied pH range. Nanoring morphology was confirmed by transmission electron microscopy and atomic force microscopy images. The nanoscale design maximizes the surface area for the molecular scavenger. A combination of all these features along with the reversible binding phenomenon has made NNRG a superior reagent for specific, efficient uptake of UO22+ species from an acidic (pH 3-4) solution and compares better than all existing UO22+-scavengers reported till date. This could be utilized for the recovery of uranyl species from a synthetic acidic effluent of the nuclear power. The results of the U uptake experiments reveal a maximum adsorption capacity of 268 mg of U per g of NNRG in a synthetic nuclear effluent. X-ray photoelectron spectroscopy studies revealed a reductive complexation process and stabilization of U(IV)-species in adsorbed uranium species (U@NNRG).

10abiodegradable polymeric backbone10amolecular recognition10ananostructured material10asodium alginate10auranium10auranyl-specific receptor1 aKushwaha, Shilpi1 aMane, Manoj1 aRavindranathan, Sapna1 aDas, Amitava uhttps://library.ncl.res.in/content/polymer-nanorings-uranium-specific-clefts-selective-recovery-uranium-acidic-effluents02555nas a2200229 4500008004100000022001400041245020200055210006900257260000800326300001400334490000700348520165500355100002302010700002502033700002502058700002102083700002602104700002402130700002702154700001702181856012702198 2021 eng d a2041-652000aPhotoactivatable prodrug for simultaneous release of mertansine and CO along with a BODIPY derivative as a luminescent marker in mitochondria: a proof of concept for NIR image-guided cancer therapy0 aPhotoactivatable prodrug for simultaneous release of mertansine  cFEB a2667-26730 v123 a

Controlled and efficient activation is the crucial aspect of designing an effective prodrug. Herein we demonstrate a proof of concept for a light activatable prodrug with desired organelle specificity. Mertansine, a benzoansamacrolide, is an efficient microtubule-targeting compound that binds at or near the vinblastine-binding site in the mitochondrial region to induce mitotic arrest and cell death through apoptosis. Despite its efficacy even in the nanomolar level, this has failed in stage 2 of human clinical trials owing to the lack of drug specificity and the deleterious systemic toxicity. To get around this problem, a recent trend is to develop an antibody-conjugatable maytansinoid with improved tumor/organelle-specificity and lesser systematic toxicity. Endogenous CO is recognized as a regulator of cellular function and for its obligatory role in cell apoptosis. CO blocks the proliferation of cancer cells and effector T cells, and the primary target is reported to be the mitochondria. We report herein a new mitochondria-specific prodrug conjugate (Pro-DC) that undergoes a photocleavage reaction on irradiation with a 400 nm source (1.0 mW cm(-2)) to induce a simultaneous release of the therapeutic components mertansine and CO along with a BODIPY derivative (BODIPY(PPH3)(2)) as a luminescent marker in the mitochondrial matrix. The efficacy of the process is demonstrated using MCF-7 cells and could effectively be visualized by probing the intracellular luminescence of BODIPY(PPH3)(2). This provides a proof-of-concept for designing a prodrug for image-guided combination therapy for mainstream treatment of cancer.

1 aTiwari, Rajeshwari1 aShinde, Prashant, S.1 aSreedharan, Sreejesh1 aDey, Anik, Kumar1 aVallis, Katherine, A.1 aMhaske, Santosh, B.1 aPramanik, Sumit, kumar1 aDas, Amitava uhttps://library.ncl.res.in/content/photoactivatable-prodrug-simultaneous-release-mertansine-and-co-along-bodipy-derivative