02265nas 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-002667nas 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-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-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-ofboolean01787nas 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-pair02225nas 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-vesicles02016nas 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-fibers