@article { ISI:000257442900006, title = {Synthesis and FTIR spectroscopic investigation of the UV curing kinetics of telechelic urethane methacrylate crosslinkers based on the renewable resource-cardanol}, journal = {Journal of Applied Polymer Science}, volume = {109}, number = {5}, year = {2008}, month = {SEP}, pages = {2781-2790}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

UV curable telechelic urethane-methacrylate crosslinkers based on the natural resource-cardanol was synthesized in a one pot synthetic step involving end capping of isophorone diisocyanate with one equivalent of hydroxyethyl methacrylate followed by condensation with cardanol. The structures of the resins were characterized by H-1 and C-13 NMR, fourier transform infrared (FTIR) and Matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) spectroscopies and size exclusion chromatography (SEC). The curing process and double bond conversion in presence of 2,2-diethoxy acetophenone as photo-initiator upon UV irradiation was followed by Fourier transform infrared spectroscopy. These hydrogen bonded crosslinkers based on cardanol and its derivatives had higher double bond conversion when compared to a nonhydrogen bonding standard such as hexanediol diacrylate (HDDA) under identical conditions. The temperature effects on the hydrogen bonding were investigated, and a decrease in the extent of double bond conversion with increase in temperature was observed for the telechelic urethane-methacrylate crosslinkers whereas a steady increase in the curing rate was observed for HDDA. This gives direct indication of the influence of hydrogen bonding on the curing process. (C) 2008 Wiley Periodicals, Inc.

}, keywords = {Cardanol, hydrogen bonding, infrared spectroscopy, renewable resource, UV curing}, issn = {0021-8995}, doi = {10.1002/app.28342}, author = {Rekha, N. and Asha, S. K.} } @article { ISI:000272871400006, title = {N-substitution of polybenzimidazoles: synthesis and evaluation of physical properties}, journal = {European Polymer Journal}, volume = {45}, number = {12}, year = {2009}, month = {DEC}, pages = {3363-3371}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Series of N-substituted polybenzimidazoles (PBI) were synthesized using selective alkyl groups with varying bulk and flexibility, viz., methyl, n-butyl, methylene trimethylsilane and 4-tert-butylbenzyl. PBl-I based on 3,3{\textquoteright}-diaminobenzidine (DAB) and isophthalic acid and PBI-Bul based on DAB and 5-tert-butyl isophthalic acid were chosen for N-substitution. Structural characterizations of substituted polymers by FT-IR and (1)H NMR revealed elimination of hydrogen bonding. Evaluation of their physical properties revealed that N-substitution rendered better solvent solubility in common organic solvents, more open polymer matrix, but reduced thermal properties in comparison to their respective parent PBI. 4-tert-butylbenzyl, methylene trimethylsilane or n-butyl group substituted polymers were soluble even in chlorinated solvents (CHCl(3) and TCE). Substantial variations in gas permeability of inert gases, He and Ar and attractive P(He)/P(Ar) selectivity, especially after methyl group substitution depicted potential of these materials for gas separation. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Gas permeation, hydrogen bonding, N-Substitution, Polybenzimidazole}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2009.10.006}, author = {Kumbharkar, Santosh C. and Kharul, Ulhas K.} } @article { ISI:000263163200021, title = {Synthesis and self-organization properties of copolyurethanes based on perylenediimide and naphthalenediimide units}, journal = {Journal of Polymer Science Part A-Polymer Chemistry}, volume = {47}, number = {4}, year = {2009}, month = {FEB}, pages = {1224-1235}, publisher = {JOHN WILEY \& SONS INC}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

A series of perylene and naphthalene diimide-containing random copolyurethanes with different ratios of perylene/naphthalene diimide content was synthesized and characterized. Copolymerization improved the solubility of these rigid aromatic diimides, and the copolymers were soluble in common organic solvents like chloroform, tetrahydrofuran, and so forth. The absorption spectra of perylene-based copolymers showed a red-shifted peak at a wavelength of 557 nm corresponding to J-type aggregates. For naphthalene copolymers, the quenching of fluorescence at higher naphthalene incorporation suggested the presence of aggregates because of the extensive pi-pi stacking of the aromatic core. FTIR spectroscopic analysis showed that the hydrogen bonding tendency of the polymer decreased with increase in perylene/naphthalene incorporation. The fluorescence spectra of the perylene polymers were exactly a mirror image of the absorption spectra. The fluorescence spectra of the naphthalene polymers at higher naphthalene incorporation showed a red-shifted excimer like emission peak, which was assigned as static excimers based on their excitation spectra. These polymers could exhibit two types of secondary interaction modes, namely, hydrogen bonding (via urethane linkage) and pi-stacking (via aromatic perylene or naphthalene units) thus highlighting the importance of polymer design in inducing self-organization at both low and high incorporation of the rigid bisimide moieties. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polyrn Chem 47: 1224-1235, 2009

}, keywords = {fluorescence, hydrogen bonding, naphthalene diimide polymers, polyurethane copolymer, self-organization, structure-property relations}, issn = {0887-624X}, doi = {10.1002/pola.23233}, author = {Jancy, B. and Asha, S. K.} } @article { ISI:000275769700022, title = {Crystal structure, NMR and theoretical investigations on 2-(o-hydroxy-anilino)-1,4-napthoquinone}, journal = {Journal of Molecular Structure}, volume = {966}, number = {1-3}, year = {2010}, month = {MAR}, pages = {144-151}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Crystal structure, (1)H NMR and cyclic voltammetric investigations of 2-(o-hydroxy-anilino)-1,4-napthoquinone (HAN), resulting from coupling of aminophenol with 2-hydroxy-1,4-napthoquinone, have been carried out. X-ray structure reveals that the HAN ligand crystallizes in orthorhombic space group Pca2(1) with Z = 4. forming a chain via inter-molecular O2 center dot center dot center dot H1A-O1 and C15-H15 center dot center dot center dot O3 interactions. Both (1)H NMR and cyclic voltammetry experiments suggest the titled ligand is associated and exists as dinner in d(6)-DMSO while the monomer has been predicted in CDCl(3) solution. Density functional calculations can be utilized to gauge the strength of hydrogen-bonded interactions from the (1)H chemical shifts in the NMR spectra. Self-consistent reaction field (SCRF) calculations further support the inferences drawn from cyclic voltammetry experiments. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {(1)H NMR, cyclic voltammetry, Density functional, hydrogen bonding, Napthoquinone}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2009.12.029}, author = {Feizi, Nourollah and Pinjari, Rahul V. and Gejji, Shridhar P. and Sayyed, Fareed B. and Gonnade, Rajesh G. and Rane, Sandhya Y.} } @article { ISI:000309208000024, title = {Ammonia clathrate hydrates as new solid phases for Titan, Enceladus, and other planetary systems}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, volume = {109}, number = {37}, year = {2012}, month = {SEP}, pages = {14785-14790}, publisher = {NATL ACAD SCIENCES}, address = {2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA}, abstract = {

There is interest in the role of ammonia on Saturn{\textquoteright}s moons Titan and Enceladus as the presence of water, methane, and ammonia under temperature and pressure conditions of the surface and interior make these moons rich environments for the study of phases formed by these materials. Ammonia is known to form solid hemi-, mono-, and dihydrate crystal phases under conditions consistent with the surface of Titan and Enceladus, but has also been assigned a role as water-ice antifreeze and methane hydrate inhibitor which is thought to contribute to the outgassing of methane clathrate hydrates into these moons{\textquoteright} atmospheres. Here we show, through direct synthesis from solution and vapor deposition experiments under conditions consistent with extraterrestrial planetary atmospheres, that ammonia forms clathrate hydrates and participates synergistically in clathrate hydrate formation in the presence of methane gas at low temperatures. The binary structure II tetrahydrofuran + ammonia, structure I ammonia, and binary structure I ammonia + methane clathrate hydrate phases synthesized have been characterized by X-ray diffraction, molecular dynamics simulation, and Raman spectroscopy methods.

}, keywords = {ethane, hydrate inhibitors, hydrogen bonding, ice, single crystal X-ray diffraction}, issn = {0027-8424}, doi = {10.1073/pnas.1205820109}, author = {Shin, Kyuchul and Kumar, Rajnish and Udachin, Konstantin A. and Alavi, Saman and Ripmeester, John A.} } @article {UGC-New Delhi}, title = {Single crystal X-ray structure of lawsone anion: evidence for coordination of alkali metal ions and formation of naphthosemiquinone radical in basic media}, journal = {Journal of Molecular Structure}, volume = {1010}, number = {3-4}, year = {2012}, month = {FEB}, pages = {38-45}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

2-hydroxy-1,4-naphthoquinone; Lawsone (Lw) is a natural compound found in henna leaves. The reaction of lawsone with {\textquoteleft}Na{\textquoteright} metal (Lw-1), CH3COONa (Lw-2), NaOH (Lw-3), KOH (Lw-4), K2CO3 (Lw-5) and Tris(hydroxymethyl)aminomethane (Lw-6) were studied. Red orange solids obtained for Lw-1 to Lw-6 are characterized by Elemental Analysis, FTIR, (HNMR)-H-1 and EPR studies. The results reveal the coordination of alkali metals {\textquoteleft}Na{\textquoteright} and {\textquoteleft}K{\textquoteright} to lawsone anion. The single crystal X-ray structure of Lw-6 was solved and it crystallizes in triclinic space group P-1 with extensive hydrogen bonding network of C-H center dot center dot center dot O, N-H center dot center dot center dot O and O-H center dot center dot center dot O between cations and anions. Polycrystalline powder X-band EPR spectra of Lw-1 to Lw-5 shows signals similar to 2.004 at 133 K, while Lw-6 is EPR silent. The naphthosemiquinone (NSQ) radical formed in Lw-2 to Lw-5, is due to disproportion reaction of catechol and naphthoquinone. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {2-Hydroxy-1, 4-naphthoquione, EPR, hydrogen bonding, Lawsone, Naphthosemiquinone radicals}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2011.11.015}, author = {Salunke-Gawali, Sunita and Kathawate, Laxmi and Shinde, Yogesh and Puranik, Vedavati G. and Weyhermueller, Thomas} } @article { ISI:000326207600012, title = {Complementation of intramolecular interactions for structural-functional stability of plant serine proteinase inhibitors}, journal = {Biochimica Et Biophysica Acta-General Subjects}, volume = {1830}, number = {11}, year = {2013}, month = {NOV}, pages = {5087-5094}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Background: Plant protease inhibitors (PIs) constitute a diverse group of proteins capable of inhibiting proteases. Among Pls, serine Pls (SPIs) display stability and conformational restrictions of the reactive site loop by virtue of their compact size, and by the presence of disulfide bonds, hydrogen bonds, and other weak interactions. Scope of review: The significance of various intramolecular interactions contributing to protein folding mechanism and their role in overall stability and activity of SPIs is discussed here. Furthermore, we have reviewed the effect of variation or manipulation of these interactions on the activity/stability of SPIs. Major conclusions: The selective gain or loss of disulfide bond(s) in SPIs can be associated with their functional differentiation, which is likely to be compensated by non-covalent interactions (hydrogen bonding or electrostatic interactions). Thus, these intramolecular interactions are collectively responsible for the functional activity of SPIs, through the maintenance of scaffold framework, conformational rigidity and shape complementarities of reactive site loop. General significance: Structural insight of these interactions will provide an in-depth understanding of kinetic and thermodynamic parameters involved in the folding and stability mechanisms of SPIs. These features can be explored for engineering canonical SPIs for optimizing their overall stability and functionality for various applications. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Disulfide bond, hydrogen bonding, Intramolecular weak interaction, Protease, Reactive site loop, Serine proteinase inhibitor}, issn = {0304-4165}, doi = {10.1016/j.bbagen.2013.07.019}, author = {Joshi, Rakesh S. and Mishra, Manasi and Suresh, C. G. and Gupta, Vidya S. and Giri, Ashok P.} } @article { ISI:000319417100005, title = {Design, synthesis, structural characterization by IR, 1H, 13C, 15N, 2D-NMR, X-ray diffraction and evaluation of a new class of phenylaminoacetic acid benzylidene hydrazines as pfENR inhibitors}, journal = {Chemical Biology \& Drug Design}, volume = {81}, number = {6}, year = {2013}, month = {JUN}, pages = {715-729}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

Recent studies have revealed that plasmodial enoyl-ACP reductase (pfENR, FabI), one of the crucial enzymes in the plasmodial type II fatty acid synthesis II (FAS II) pathway, is a promising target for liver stage malaria infections. Hence, pfENR inhibitors have the potential to be used as causal malarial prophylactic agents. In this study, we report the design, synthesis, structural characterization and evaluation of a new class of pfENR inhibitors. The search for inhibitors began with a virtual screen of the iResearch database by molecular docking. Hits obtained from the virtual screen were ranked according to their Glide score. One hit was selected as a lead and modified to improve its binding to pfENR; from this, a series of phenylamino acetic acid benzylidene hydrazides were designed and synthesized. These molecules were thoroughly characterized by IR, 1H, 13C, 15N, 2D-NMR (COSY, NOESY, 1H-13C, 1H-15N HSQC and HMBC), and X-ray diffraction. NMR studies revealed the existence of conformational/configurational isomers around the amide and imine functionalities. The major species in DMSO solution is the E, E form, which is in dynamic equilibrium with the Z, E isomer. In the solid state, the molecule has a completely extended conformation and forms helical structures that are stabilized by strong hydrogen bond interactions, forming a helical structure stabilized by N-H...O interactions, a feature unique to this class of compounds. Furthermore, detailed investigation of the NMR spectra indicated the presence of a minor impurity in most compounds. The structure of this impurity was deduced as an imidazoline-4-one derivative based on 1H-13C and 1H-15H HMBC spectra and was confirmed from the NOESY spectra. The molecules were screened for in vitro activity against recombinant pfENR enzyme by a spectrophotometric assay. Four molecules, viz. 17, 7, 10, and 12 were found to be active at 7, 8, 10, and 12m concentration, respectively, showing promising pfENR inhibitory potential. A classification model was derived based on a binary QSAR approach termed recursive partitioning (RP) to highlight structural characteristics that could be tuned to improve activity.

}, keywords = {ADMET, docking, enoyl-ACP reductase, FabI, hydrogen bonding, NMR, phenylaminoacetic acid benzylidene hydrazine, Plasmodium falciparum, Plasmodium falciparum enoyl-ACP reductase, QSAR, recursive partitioning, X-ray diffraction}, issn = {1747-0277}, doi = {10.1111/cbdd.12118}, author = {Samal, Ramanuj P. and Khedkar, Vijay M. and Pissurlenkar, Raghuvir R. S. and Bwalya, Angela Gono and Tasdemir, Deniz and Joshi, Ramesh A. and Rajamohanan, P. R. and Puranik, Vedavati G. and Coutinho, Evans C.} } @article { ISI:000323468500032, title = {Synthesis and molecular structure of a zinc complex of the vitamin K-3 analogue phthiocol}, journal = {Journal of Molecular Structure}, volume = {1048}, year = {2013}, month = {SEP}, pages = {223-229}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The complex [Zn(phthiocol)(2)(H2O)(2)]; 1, where phthiocol is 2-hydroxy-3-methyl-1,4-naphthoquinone, has been synthesized and characterized by elemental analysis, FT-IR, H-1 NMR, UV-vis spectroscopy, thermogravimetric (TG) analysis, electrochemical and single crystal X-ray diffraction studies. The v(C=O) stretch shifts to lower frequencies upon complexation of phthiocol to Zn2+. H-1 NMR spectra show an upfield shift of the benzenoid ring protons in 1. There is a bathochromic shift of the LMCT band in the UV-vis spectra of 1. Single crystal X-ray structure of 1 show distorted octahedral geometry around Zn2+. Two phthiocol ligands are in plane with the metal, while water molecules are trans to this plane. Coordination of deprotonated phthiocol ligands is {\textquoteleft}trans, trans{\textquoteright} to Zn2+. Intra as well as intermolecular interactions are observed in 1. Molecules of 1 show three dimensional network through C-H center dot center dot center dot O and O-H center dot center dot center dot O interactions. Additional anodic peaks are observed in cyclic voltammogram of phthiocol ligand due to oxidation of reduced species formed during reduction. One-electron reduction of 1 is shown to be reversible and DFT studies define this redox event as ligand-centered. (c) 2013 Elsevier B.V. All rights reserved.

}, keywords = {hydrogen bonding, Naphthoquinone, Phthiocol, Trans coordination, Vitamin K-3, Zinc complex}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2013.05.057}, author = {Kathawate, Laxmi and Sproules, Stephen and Pawar, Omkar and Markad, Ganesh and Haram, Santosh K. and Puranik, Vedavati G. and Salunke-Gawali, Sunita} } @article { ISI:000344793700010, title = {Correlation of the solid-state reactivities of racemic 2,4(6)-di-O-benzoyl-myo-inositol 1,3,5-orthoformate and its 4,4 {\textquoteleft}-bipyridine cocrystal with their crystal structures}, journal = {Acta Crystallographica Section C-Structural Chemistry}, volume = {70}, number = {11}, year = {2014}, month = {NOV}, pages = {1040+}, publisher = {WILEY-BLACKWELL}, type = {Article}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

Racemic 2,4(6)-di-O-benzoyl-myo-inositol 1,3,5-orthoformate, C21H18O8, (1), shows a very efficient intermolecular benzoyl-group migration reaction in its crystals. However, the presence of 4,4 {\textquoteleft}-bipyridine molecules in its cocrystal, C21H18O8 center dot C10H8N2, (1)center dot BP, inhibits the intermolecular benzoyl-group transfer reaction. In (1), molecules are assembled around the crystallographic twofold screw axis (b axis) to form a helical self-assembly through conventional O-H center dot center dot center dot O hydrogen-bonding interactions. This helical association places the reactive C6-O-benzoyl group (electrophile, El) and the C4-hydroxy group (nucleophile, Nu) in proximity, with a preorganized El center dot center dot center dot Nu geometry favourable for the acyl transfer reaction. In the cocrystal (1)center dot BP, the dibenzoate and bipyridine molecules are arranged alternately through OH center dot center dot center dot N interactions. The presence of the bipyridine molecules perturbs the regular helical assembly of the dibenzoate molecules and thus restricts the solid-state reactivity. Hence, unlike the parent dibenzoate crystals, the cocrystals do not exhibit benzoyl-transfer reactions. This approach is useful for increasing the stability of small molecules in the crystalline state and could find application in the design of functional solids.

}, keywords = {acyl transfer, cocrystal, crystal structure, design of functional solids, helical assembly, hydrogen bonding, myo-inositol, solid-state reactions}, issn = {0108-2701}, doi = {10.1107/S2053229614021834}, author = {Tamboli, Majid I. and Bahadur, Vir and Gonnade, Rajesh G. and Shashidhar, Mysore S.} } @article { ISI:000345826600002, title = {Heterogeneous foldamers from aliphatic-aromatic amino acid building blocks: current trends and future prospects}, journal = {European Journal of Organic Chemistry}, volume = {46}, number = {35}, year = {2014}, month = {DEC}, pages = {7763-7780}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

Chemists{\textquoteright} constant pursuit of understanding of the underlying principles of nature{\textquoteright}s most intricate phenomenon such as protein folding has led to the development of the field of foldamers. The emergence of diverse classes of unnatural amino acid building blocks has unleashed countless opportunities to design, develop and explore the structural and functional aspects of synthetic peptides. One current trend in foldamer chemistry is the heterofoldamer approach, which involves systematic stoichiometric variation of various natural/unnatural amino acid residues, leading to conformational ordering with intriguing structural architectures. In this regard, the incorporation of aromatic amino acids provides efficient structural rigidification and tunability to the molecular scaffolds, which can exhibit a range of secondary structural features. Recent times have witnessed an upsurge of foldamers featuring aliphatic-aromatic residues with diverse structural propensities. This review is an effort to cover this rapidly developing field of foldamer science and also to envisage its future perspectives.

}, keywords = {Amino acids, Conformation analysis, Foldamers, hydrogen bonding, Peptides, Stacking interactions}, issn = {1434-193X}, doi = {10.1002/ejoc.201402877}, author = {Nair, Roshna V. and Vijayadas, Kuruppanthara N. and Roy, Arup and Sanjayan, Gangadhar J.} } @article { ISI:000344978200129, title = {Nanostructured donor-acceptor self assembly with improved photoconductivity}, journal = {ACS Applied Materials \& Interfaces}, volume = {6}, number = {21}, year = {2014}, month = {NOV}, pages = {19434-19448}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Nanostructured supramolecular donor-acceptor assemblies were formed when an unsymmetrical N-substituted pyridine functionalized perylenebisimide (UPBI-Py) was complexed with oligo(p-phenylenevinylene) (OPVM-OH) complementarily functionalized with hydroxyl unit and polymerizable methacrylamide unit at the two termini. The resulting supramolecular complex [UPBI-Py (OPVM-OH)](1.0) upon polymerization by irradiation in the presence of photoinitiator formed well-defined supramolecular polymeric nanostructures. Self-assembly studies using fluorescence emission from thin film samples showed that subtle structural changes occurred on the OPV donor moiety following polymerization. The 1:1 supramolecular complex showed red-shifted aggregate emission from both OPV (similar to 500 nm) and PBI (similar to 640 nm) units, whereas the OPV aggregate emission was replaced by intense monomeric emission (similar to 430 nrn) upon polymerizing the methacrylamide units on the OPVM-OH. The bulk structure was studied using wide-angle X-ray diffraction (WXRD). Complex formation resulted in distinct changes in the cell parameters of OPVM-OH. In contrast, a physical mixture of 1 mol each of OPVM-OH and UPBI-Py prepared by mixing the powdered solid samples together showed only a combination of reflections from both parent molecules. Thin film morphology of the 1:1 molecular complex as well as the supramolecular polymer complex showed uniform lamellar structures in the domain range \<10 rim. The donor-acceptor supramolecular complex [UPBI-Py (OPVM-OH)](1.0) exhibited space charge limited current (SCLC) with a bulk mobility estimate of an order of magnitude higher accompanied by a higher photoconductivity yield compared to the pristine UPBI-Py. This is a very versatile method to obtain spatially defined organization of n and p-type semiconductor materials based on suitably functionalized donor and acceptor molecules resulting in improved photocurrent response using self-assembly.

}, keywords = {donor-acceptor, hydrogen bonding, oligo(p-phenylenevinylene), Perylenebisimide, photoconductivity, supramolecular polymeric nanostructures}, issn = {1944-8244}, doi = {10.1021/am5055542}, author = {Saibal, B. and Ashar, A. Z. and Devi, R. Nandini and Narayan, K. S. and Asha, S. K.} } @article { ISI:000345082000021, title = {Structural diversity in serine derived homochiral metal organic frameworks}, journal = {Journal of Chemical Sciences}, volume = {126}, number = {5, SI}, year = {2014}, month = {SEP}, pages = {1399-1408}, publisher = {INDIAN ACAD SCIENCES}, address = {C V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIA}, abstract = {

Two new Zn(II) and Cd(II) based homochiral metal-organic frameworks (MOFs) [SerCdOAc and Zn(Ser)(2)] have been synthesized using pyridyl functionalized amino acid, viz., serine, as an organic linker. The SerCdOAc structure is three dimensional, while that of the Zn(Ser)(2) is two dimensional. The polar voids of the corresponding MOFs are filled with solvent molecules (water in the case of SerCdOAc and methanol in the case of Zn(Ser)(2)). In both cases, metal centres, i.e., Zn(II) and Cd(II), are hexacoordinated. However, with a change in the solvent for synthesis, ligand coordination mode and incorporation of additional coordinated anion resulted in a great change in the final MOF architecture. Herein, for the first time, we could achieve structural variety and synthesize MOFs composed of only metal ion and pyridyl functionalized amino acid linker.

}, keywords = {Amino acid, crystal engineering, hydrogen bonding, metal organic framework}, issn = {0974-3626}, doi = {10.1007/s12039-014-0714-9}, author = {Kundu, Tanay and Banerjee, Rahul} } @article { ISI:000330147900013, title = {Synthesis, characterization and molecular structures of homologated analogs of 2-bromo-3-(n-alkylamino)-1,4-napthoquinone}, journal = {Journal of Molecular Structure}, volume = {1056}, year = {2014}, month = {JAN}, pages = {97-103}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Four analogues of 2-bromo-3-(n-alkylamino)-1,4-napthoquinone (where n-alkyl is methyl in L-1Br, ethyl in L-2Br, propyl in L-3Br and butyl in L-4Br) are synthesized and characterized. A reaction mechanism is proposed for the formation of L-1 Br to L-4Br from the starting material 2,3-dibromo-1,4-naphthoquinone. The v(N-H) frequency in the FT-IR spectra is affected by the intramolecular hydrogen bonding in L-1Br to L-4Br and is observed similar to 3267 cm(-1) in L-2Br. A shift of similar to 25 cm(-1) is observed in the v(C-Br) frequency in all the compounds as compared to 2,3-dibromo-1,4-naphthoquinone (627 cm(-1)). A broad charge transfer band is observed between 400 and 600 nm in the UV-Vis spectra, which imparts red colour to all the compounds. Molecular structures of L-2Br and L-3Br were studied by single crystal X-ray diffraction studies. Molecules of L-2Br crystallize in Pca2(1), whereas the molecule L-3Br crystallizes in the P-1 space group. Molecules of L-2Br forms a polymeric chain through N-H...O interaction and forms beautiful butterfly like arrangement of molecules when viewed down the {\textquoteleft}a{\textquoteright} axis. Ladder like polymeric chain of molecules is observed in L-3Br via C-H...O and N-H...O interactions. Every alternating neighbouring chains of L-3Br, show pi-pi stacking interactions between the quinonoid rings of the molecules, however this interaction is not observed in L-2Br. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {2, 3-Dibromo-1, 4-naphthoquinone, Aminonaphthoquinone, hydrogen bonding, Michael addition, pi-pi stacking}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2013.10.016}, author = {Salunke-Gawali, Sunita and Pawar, Omkar and Nikalje, Milind and Patil, Rishikesh and Weyhermueller, Thomas and Puranik, Vedavati G. and Konkimalla, V. Badireenath} } @article { ISI:000364509100013, title = {Crystal structures of the pyrazinamide-p-aminobenzoic acid (1/1) cocrystal and the transamidation reaction product 4-(pyrazine-2-carboxamido)-benzoic acid in the molten state}, journal = {Acta Crystallographica Section C-Structural Chemistry}, volume = {71}, number = {11}, year = {2015}, month = {NOV}, pages = {1010-U276}, publisher = {INT UNION CRYSTALLOGRAPHY}, address = {2 ABBEY SQ, CHESTER, CH1 2HU, ENGLAND}, abstract = {

The synthesis of pharmaceutical cocrystals is a strategy to enhance the performance of active pharmaceutical ingredients (APIs) without affecting their therapeutic efficiency. The 1: 1 pharmaceutical cocrystal of the antituberculosis drug pyrazinamide (PZA) and the cocrystal former p-aminobenzoic acid (p-ABA), C7H7NO2- C5H5N3O, (1), was synthesized successfully and characterized by relevant solid-state characterization methods. The cocrystal crystallizes in the monoclinic space group P21/n containing one molecule of each component. Both molecules associate via intermolecular O-H center dot center dot center dot O and NH center dot center dot center dot O hydrogen bonds [O center dot center dot center dot O = 2.6102 (15)angstrom and O-H center dot center dot center dot O = 168.3 (19)degrees; N center dot center dot center dot O = 2.9259 (18) angstrom and N-H center dot center dot center dot O = 167.7 (16)degrees] to generate a dimeric acidamide synthon. Neighbouring dimers are linked centrosymmetrically through N-H center dot center dot center dot O interactions [N center dot center dot center dot O = 3.1201 (18) angstrom and N-H center dot center dot center dot O = 136.9 (14)degrees] to form a tetrameric assembly supplemented by C-H center dot center dot center dot N interactions [C center dot center dot center dot N = 3.5277 (19) angstrom and C-H center dot center dot center dot N = 147 degrees]. Linking of these tetrameric assemblies through N-H center dot center dot center dot O [N center dot center dot center dot O = 3.3026 (19) angstrom and N-H center dot center dot center dot O = 143.1 (17)degrees], NH center dot center dot center dot N [N center dot center dot center dot N = 3.221 (2) angstrom and N-H center dot center dot center dot N = 177.9 (17)degrees] and C-H center dot center dot center dot O [C center dot center dot center dot O = 3.5354 (18) angstrom and C-H center dot center dot center dot O = 152 degrees] interactions creates the twodimensional packing. Recrystallization of the cocrystals from the molten state revealed the formation of 4-(pyrazine-2-carboxamido) benzoic acid, C12H9N3O3, (2), through a transamidation reaction between PZA and p-ABA. Carboxamide (2) crystallizes in the triclinic space group P1 with one molecule in the asymmetric unit. Molecules of (2) form a centrosymmetric dimeric homosynthon through an acid-acid O-H center dot center dot center dot O hydrogen bond [O center dot center dot center dot O = 2.666 (3) angstrom and O-H center dot center dot center dot O = 178 (4) degrees]. Neighbouring assemblies are connected centrosymmetrically via a C-H center dot center dot center dot N interaction [C center dot center dot center dot N = 3.365 (3) angstrom and C-H center dot center dot center dot N = 142 degrees] engaging the pyrazine groups to generate a linear chain. Adjacent chains are connected loosely via C-H center dot center dot center dot O interactions [C center dot center dot center dot O = 3.212 (3) angstrom and CH center dot center dot center dot O = 149 degrees] to generate a two-dimensional sheet structure. Closely associated two-dimensional sheets in both compounds are stacked via aromatic pi-stacking interactions engaging the pyrazine and benzene rings to create a threedimensional multi-stack structure.

}, keywords = {acid-amide hetero-synthon, active pharmaceutical ingredient (API), cocrystal, crystal structure, hydrogen bonding, molten-state reaction, powder diffraction, transamidation reaction}, issn = {2053-2296}, doi = {10.1107/S2053229615019828}, author = {Thorat, Shridhar H. and Sahu, Sanjay Kumar and Gonnade, Rajesh G.} } @article { ISI:000351969900008, title = {First naphthosemiquinone complex of K+ with vitamin K3 analog: experiment and density functional theory}, journal = {Journal of Molecular Structure}, volume = {1088}, year = {2015}, month = {MAY}, pages = {56-63}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Synthesis and characterization of potassium complex of 2-hydroxy-3-methyl-1,4-naphthoquinone (phthiocol), the vitamin K3 analog, has been carried out using FT-IR, UV-Vis, H-1 and C-13 NMR, EPR, cyclic voltammetry and single crystal X-ray diffraction experiments combined with the density functional theory. It has been observed that naphthosemiquinone binds to two K+ ions extending the polymeric chain through bridging oxygens O(2) and O(3). The crystal network possesses hydrogen bonding interactions from coordinated water molecules showing water channels along the c-axis. C-13 NMR spectra revealed that the complexation of phthiocol with potassium ion engenders deshielding of C(2) signals, which appear at delta = similar to 14.6 ppm whereas those of C(3) exhibit up-field signals near delta similar to 6.9 ppm. These inferences are supported by the M06-2x based density functional theory. Electrochemical experiments further suggest that reduction of naphthosemiquinone results in only a cathodic peak from catechol. A triplet state arising from interactions between neighboring phthiocol anion lead to a half field signal at g = 4.1 in the polycrystalline X-band EPR spectra at 133 K. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {C-13 NMR, DFT, hydrogen bonding, Naphthosemiquinone, Phthiocol, Vitamin K3}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2015.01.053}, author = {Kathawate, Laxmi and Gejji, Shridhar P. and Yeole, Sachin D. and Verma, Prakash L. and Puranik, Vedavati G. and Salunke-Gawali, Sunita} } @article { ISI:000355064000014, title = {Self-assembly directed template photopolymerization of perylenebisimide-poly (4-vinylpyridine): nano organization}, journal = {Polymer}, volume = {65}, year = {2015}, month = {MAY}, pages = {115-123}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

A perylene bisimide derivative (PDP-UPBIAcry) having hydroxyl moieties at one termini and polymerizable acrylic units at the other termini was supramolecularly complexed with the pyridine units of Poly (4-vinyl pyridine) (P4VP), followed by photoinduced polymerization of the acrylic units to obtain lamellar organization in the \<10 nm range. H-1 NMR studies including variable temperature (20 degrees C-70 degrees C) measurements were undertaken in DMSO-d(6) (anhydrous, extra dry) to understand the interaction between PDP-UPBIAcry and P4VP. The aromatic perylene protons of PDP-UPBIAcry registered an upfield chemical shift while the pyridine protons of P4VP exhibited small downfield shift in their 1:1 supramolecular complex. The hydrogen bonding interaction between pyridyl nitrogen and phenolic OH group was also traced in non-polar media like CDCl3 in model complexes of 4-vinyl pyridine (4VP) with PDP-UPBIAcry. Wide angle X-ray diffraction (WXRD) technique was used to study the bulk structure. Transmission electron microscopy (TEM) imaging revealed highly ordered layered assembly formed upon complexation. Observation from DFT energy minimization studies were correlated with X-ray diffraction data of the supramolecular complex [P4VP (PDP-UPBIAcry)](1.0) to understand the nature of packing of PDP-UPBIAcry that lead to the formation of highly ordered lamellar stacks alternating with P4VP. The higher ordering in the supramolecular polymer complex was also confirmed by the quenching of fluorescence and reduced fluorescence life times of thin solid films of the [P4VP Poly(PDP-UPBIAcry)](1.0) sample. (C) 2015 Elsevier Ltd. All rights reserved.

}, keywords = {hydrogen bonding, P4VP, Perylenebisimide}, issn = {0032-3861}, doi = {10.1016/j.polymer.2015.03.062}, author = {Shinde, Shekhar and Asha, S. K.} } @article { ISI:000374073800014, title = {Naphthoquinone based chemosensor 2-(2 {\textquoteleft}-aminoethylpyridine)-3-chloro-1,4-naphthoquinone: detection of metal ions, X-ray -crystal structures and DFT studies}, journal = {Journal of Molecular Structure}, volume = {1114}, year = {2016}, month = {JUN}, pages = {132-143}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Naphthoquinone based Chemosensor 2; 2-(2{\textquoteright}-aminoethylpyridine)-3-chloro-1,4-napthoquinone have been synthesized and characterized. Chemosensor 2 crystallizes in the orthorhombic space group Pbcn and shows extensive intramolecular as well as intermolecular hydrogen bonding interactions. Each molecule of Chemosensor 2 showed interaction with five neighboring molecules via C-H center dot center dot center dot N, N-H center dot center dot center dot N, C-H center dot center dot center dot Cl and C-H center dot center dot center dot O interactions. Slipped pi-pi stacking interaction was observed in adjacent quinonoid and benzenoid rings. Chemosensor abilities of Chemosensor 2 ligand have been evaluated with metal ions viz. Cu2+, Ni2+, Zn2+, Co2+, Fe3+, Mn2+, Cr3+, Hg2+, La3+ and Cd2+ in methanol, methanol-water mixture and in presence of mild base triethylamine. Stoichiometry of Chemosensor 2 with metal ions such as Cu2+, Ni2+, Zn2+ and Co2+ ions was determined by Jobs method in methanol and were found as 1:1 for Cu2+ and 2:1 for Ni2+, Zn2+ Co2+. The variation in the metal ligand ratio is observed in aqueous media for Cu2+. Chemosensor 2 can be used selectively for naked eye detection of Cu2+ ions. The association constant obtained in methanol shows the trend Cu2+\>Ni2+\>Co2+. Cu2+ and two (Ni-1 and Ni-2) Ni2+ complexes were synthesized. Ni-2 complex showed coordination of Chemosensor 2 ligands was through pyridine nitrogen{\textquoteright}s only. The Chemosensor 2 and its deprotonated forms in methanol, water and triethylamine were also studied by TD-DFT studies. (C) 2016 Elsevier B.V. All rights reserved.

}, keywords = {Aminonaphthoquinone, Chemosensor, hydrogen bonding, Naphthoquinone, pi-pi stacking, TD-DFT}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2016.02.065}, author = {Patil, Amit and Ware, Anuja P. and Bhand, Sujit and Chakravarty, Debamitra K. and Gonnade, Rajesh G. and Pingale, Subhash S. and Salunke-Gawali, Sunita} } @article {43904, title = {Binding selectivity of vitamin K3 based chemosensors towards nickel(II) and copper(II) metal ions}, journal = {Journal of molecular Structure}, volume = {1143}, year = {2017}, month = {SEP}, chapter = {495-514}, abstract = {

The vitamin K3 derivatives 2-methyl-3-[(pyridin-2-ylmethyl)-amino]-1,4-naphthoquinone (M-1), 2-methyl-3-[(pyridin-2-ylethyl)-amino]-1,4-naphthoquinone (M-2), 2-methyl-3-((2-(thiophen-2-yl) methyl)amino)naphthalene-1,4-dione (M-3) and 2-methyl-3-((2-(thiophen-2-yl)ethyl)amino)naphthalene-1,4-dione (M-4) have been synthesized, characterized and studied for their chemosensor abilities towards transition metal ions. Crystal structures of M-1 to M-4 revealed a variety of N-H center dot center dot O, C-H center dot center dot center dot O, C-H center dot center dot center dot pi and pi center dot center dot center dot pi interactions. Minor variations in such interactions by chemical stimuli such as metal ions, results in change in color that can be visualized by naked eyes. It has been shown that electronic structure and H-1 NMR, vibrational as well as electronic spectra from the density functional theory agree well with the experiments. The metal ion binding in ethanol, ethanol-water and in mild base triethylamine brings forth recognizing ability of M-1 toward Ni2+ whereas M-2 exhibits large sensing ability for Cu2+ ion. Interestingly M-1 display varying metal ion binding specificity in different solvents with the association constant in ethanol being 11,786 M-1 for Ni2+ compared to 9462 M-1 for the Cu2+. A reversal in preferential binding of M-2 with the respective association constants being 4190 M-1 and 6370 M-1 is discernible. (C) 2017 Elsevier B.V. All rights reserved.

}, keywords = {Aminonaphthoquinone Molecular-structures, Anthraquinone, Aqueous-solution, Chemosensor, Crystal-structures, Cu(II), Derivatives, DFT, Fluorometric Chemosensors, hydrogen bonding, Naphthoquinone, pi-pi stacking, Recognition, sensors}, issn = {0022-2860}, doi = {10.1016/j.molstruc.2017.04.094}, author = {Patil, Amit and Lande, Dipali N. and Nalkar, Archana and (Gejji, Shridhar P. and Chakrovorty, Debamitra and Gonnade, Rajesh and Moniz, Tania and Rangel, Maria and Pereira, Eulalia and Salunke-Gawali, Sunita} } @article {45700, title = {Liquid crystalline supramolecular crosslinked polymer complexes of ditopic rylenebisimides and P4VP}, journal = {Journal of Polymer Science Part A-Polymer Chemistry}, volume = {55}, year = {2017}, month = {MAR}, pages = {951-959}, type = {Article}, abstract = {

Perylenebisimide and naphthalenebisimide (PBIPDP and NBI-PDP) end functionalized with pentadecyl phenol is designed as ditopic hydrogen bonding acceptors to form supramolecular crosslinked network with poly(4-vinyl pyridine) (P4VP). The pristine PBI-PDP has been grown as single crystals from DCM-MeOH (dichloromethane-methanol) mixture at room temperature, which revealed a P21 space group. Noticeably, the pentadecyl alkyl chain shields the aromatic perylene core on both sides resulting in the absence of p-p interaction in single-crystal assembly. The naphthalenebisimide derivative exhibits thermotropic liquid crystalline behavior, while both the molecules exhibits lyotropic liquid crystalline phases in tetrahydrofuran (THF), which were characterized using a combination of differential scanning calorimeter, X-ray diffraction, and polarized light microscopy. The hydrogen-bonded complex of both the rylenebisimides with P4VP preserves the mesomorphic properties in THF. The electron transport mobility measured by space charge limited current measurements reveals a two orders of magnitude increase in the charge transport in the P4VP complex compared to that of the pristine molecule. The average electron mobility obtained is mu(e, avg): 10(-3) cm(2)/Vs for P4VP-PBI compared to mu(e, avg): 10(-5) cm(2)/Vs for pristine PBI derivative. (C) 2017 Wiley Periodicals, Inc.

}, keywords = {crystal structures, ditopic rylenebisimide, hydrogen bonding, lyotropic liquid crystal, P4VP, Self-assembly, supramolecular crosslink, supramolecular structures}, issn = {0887-624X}, doi = {10.1002/pola.28449}, author = {Saibal, B. and Narayan, Rekha and Chithiravel, S. and Asha, S. K.} } @article {45740, title = {Mechanochemical synthesis of N-salicylideneaniline: thermosalient effect of polymorphic crystals}, journal = {IUCRJ}, volume = {4}, year = {2017}, month = {MAY}, pages = {243-250}, type = {Article}, abstract = {

Polymorphs of the dichloro derivative of N-salicylideneaniline exhibit mechanical responses such as jumping (Forms I and III) and exploding (Form II) in its three polymorphs. The molecules are connected via the amide N-H center dot center dot center dot O dimer synthon and C-Cl center dot center dot center dot O halogen bond in the three crystal structures. A fourth high-temperature Form IV was confirmed by variable-temperature single-crystal X-ray diffraction at 180 degrees C. The behaviour of jumping exhibited by the polymorphic crystals of Forms I and III is due to the layered sheet morphology and the transmission of thermal stress in a single direction, compared with the corrugated sheet structure of Form II such that heat dissipation is more isotropic causing blasting. The role of weak C-Cl center dot center dot center dot O interactions in the thermal response of molecular crystals is discussed.

}, keywords = {crystal design, crystal engineering, Halogen bonding, hydrogen bonding, intermolecular interactions, materials science, mechanochemistry, polymorphism}, issn = {2052-2525}, doi = {10.1107/S2052252517004043}, author = {Mittapalli, Sudhir and Perumalla, D. Sravanakumar and Nangia, Ashwini} } @article {44616, title = {Flexible composite mechanical energy harvester from a ferroelectric organoamino phosphonium salt}, journal = {Angewandte Chemie-International Edition}, volume = {57}, year = {2018}, month = {JUL}, pages = {9054-9058}, abstract = {

A new binary organic salt diphenyl diisopropylamino phosphonium hexaflurophosphate (DPDPPF6) was shown to exhibit a good ferroelectric response and employed for mechanical energy harvesting application. The phosphonium salt crystallizes in the monoclinic noncentrosymmetric space group Cc and exhibits an H-bonded 1D chain structure due to N-HF interactions. Ferroelectric measurements on the single crystals of DPDPPF6 gave a well-saturated rectangular hysteresis loop with a remnant (P-r) polarization value of 6Ccm(-2). Further, composite devices based on polydimethylsiloxane (PDMS) films for various weight percentages (3, 5, 7, 10 and 20wt\%) of DPDPPF6 were prepared and examined for power generation by using an impact test setup. A maximum output peak-to-peak voltage (V-PP) of 8.5V and an output peak-to-peak current (I-PP) of 0.5A was obtained for the non-poled composite film with 10wt\% of DPDPPF6. These results show the efficacy of organic ferroelectric substances as potential micropower generators.

}, keywords = {binary phosphonium salts, energy conversion, ferroelectricity, hydrogen bonding, polymer composites}, issn = {1433-7851}, doi = {10.1002/anie.201805479}, author = {Vijayakanth, Thangavel and Srivastava, Anant Kumar and Ram, Farsa and Kulkarni, Priyangi and Shanmuganathan, Kadhiravan and Praveenkumar, Balu and Boomishankar, Ramamoorthy} } @article {46318, title = {Dimedone-based rigid organic scaffold for organizing symmetrical helical peptide chains.}, journal = {ChemistrySelect}, volume = {4}, year = {2019}, month = {OCT }, pages = {11518-11522}, type = {Article}, abstract = {

We describe herein design, synthesis and conformational investigations of polypeptides attached on a rigid dimedone template. Two identical peptide chains are attached on a single carbon containing dimedone as a scaffold. Dimedone assists in controlling the secondary interactions through strong intramolecular helical C-12 and C-15 membered bifurcated hydrogen bonding on both the peptide chains along with propagating the helical architecture of the peptide chains attached. There exists a C-6 hydrogen bonding for the single stranded peptides attached to dimedone. Extensive structural investigations involving single crystal X-ray diffraction, solution-state NMR and CD studies of oligopeptides have been undertaken.

}, keywords = {dimedone, Helical, hydrogen bonding, Peptides, template}, issn = {2365-6549}, doi = {10.1002/slct.201903087}, author = {Madica, Krishnaprasad and Lakshmi, Jerripothula K. and Madhu, Suresh and Nadimpally, Krishna Chaitanya and Gonnade, Rajesh and Jagadeesh, Bharatam and Sanjayan, Gangadhar J.} }