00770nas 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-ion01847nas 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-nanoparticles01761nas 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-bound01840nas 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-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-001330nas 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-mitochondria01412nas 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-cells