Faculty Publications
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Item Electron irradiation effects on optical properties of semiorganic antimony thiourea tetra chloride single crystals(2012) Mahesha Upadhya, K.; Udayashankar, N.K.; Ganesh, S.Antimony thiourea tetra chloride single crystals were grown by solution growth technique at room temperature. The UV-visible, fourier transform infrared and fluorescence spectra were recorded and electron irradiation effects on these properties were studied. The optical absorption edge of the UV-visible spectrum slightly shifts towards longer wavelength with the increase of irradiation dose. The fluorescence quantum yield is decreased for electron irradiated antimony thiourea tetra chloride crystals. The presence of functional group of the as-grown and electron irradiated complex was confirmed by fourier transform infrared spectral study. © 2012 Elsevier B.V. All rights reserved.Item Dual colorimetric receptor with logic gate operations: Anion induced solvatochromism(Royal Society of Chemistry, 2014) Kigga, M.; Swathi, N.; Manjunatha, J.R.; Das, U.K.; Nityananda Shetty, A.N.; Trivedi, D.R.A receptor R1 was designed and synthesised for colorimetric detection of F- ions as well as Cu2+ ions via intramolecular charge transfer mechanism. Upon addition of F- ions in dry DMSO, the color of the receptor R1 changed from pale yellow to blue. The receptor showed a unique property of solvatochromism by displaying different coloration with different solvents only in the presence of F- ions, which were applied to determine the percentage composition of binary solvent mixtures. The receptor R1 was able to detect Cu2+ ions colorimetrically where it exhibited a color change from pale yellow to orange-red. In addition, the receptor was subjected to molecular logic gate applications, wherein it showed 'ON-OFF' switching operations. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item An Efficient Three-component, One-pot Synthesis of Quinazolines under Solvent-free and Catalyst-free Condition(HeteroCorporation support@jhetchem.com, 2015) Bhat, S.I.; Das, U.K.; Trivedi, D.R.An efficient green protocol for the synthesis of quinazolines in the absence of solvent and catalyst has been developed. 2,4-Disubstituted quinazolines have been synthesized from three-component one-pot reactions of 2-aminoaryl ketones, orthoesters, and ammonium acetate. The present method has advantages of operational simplicity, substrate generality, clean reaction, high yields (76-94%), and moderate reaction time. The plausible mechanism of the reaction has been proposed based on the spectral characterization and single crystal X-ray analysis of isolated intermediate. © 2014 HeteroCorporation.Item New carbazole based metal-free organic dyes with D-?-A-?-A architecture for DSSCs: Synthesis, theoretical and cell performance studies(Elsevier Ltd, 2017) Naik, P.; Elmorsy, M.R.; Su, R.; Babu, D.D.; El-Shafei, A.; Vasudeva Adhikari, A.V.Herein we report the design, synthesis and photovoltaic performance studies of three new D-?-A-?-A architectured organic chromophores (N1-3) derived from (Z)-3-(9-hexyl-9H-carbazol-3-yl)-2-(thiophen-2-yl) acrylonitrile scaffold. In the new design, the electron rich carbazole unit is connected to three different electron withdrawing/anchoring species, viz. cyano acetic acid, rhodanine-3-acetic acid and barbituric acid via cyano vinyl thiophene as ?-spacer. Newly synthesized dyes were characterized by spectral, photophysical and electrochemical analyses. Their optical band-gap, GSOP and ESOP values, as calculated from the optical and CV studies were found to be in the range of 2.12–2.21, ?5.52 to ?5.43 and ?5.40 to ?3.25 eV respectively. The DFT and TD-DFT studies were performed using Turbomole 7.1V software and the results indicated the existence of proper charge separation between HOMO and LUMO levels of the dyes. Also, the results revealed good matching of theoretically generated optical spectral data with the experimental values. Finally, DSSC devices were fabricated using these three dyes and the dye N1 containing cyanoacetic acid as an acceptor unit showed better photo conversion efficiency (?) of 3.55% than the other two dyes. It's JSC, VOC, and IPCE parameters were shown to be 9.06 mA cm?2, 0.577 V and 48%, respectively. The obtained EIS data and electron lifetimes of N1–3 sensitized devices are well in accordance with experimental photovoltaic parameters. © 2017 Elsevier LtdItem Highly efficient carbazole based co-sensitizers carrying electron deficient barbituric acid for NCSU-10 sensitized DSSCs(Elsevier Ltd, 2018) Naik, P.; Keremane, K.S.; Elmorsy, M.R.; Su, R.; El-Shafei, A.; Vasudeva Adhikari, A.V.Herein, we report a comparative study of four interesting metal-free carbazole based organic dyes with different structural configurations, carrying electron deficient barbituric acid (C1-4), as effective co-sensitizers in DSSCs sensitized with NCSU-10 dye. The new entities comprise different structural architectures, viz. D-A (C1), D-?-A (C2), D-D-?-A (C3) and D-A-?-A (C4) configurations with same accepting/anchoring moiety. They consist of carbazole as donor scaffold linked to barbituric acid as an acceptor/anchoring unit via different ?-spacers. This paper describes the study of all the four co-sensitizers with regard to their structural, photophysical, electrochemical, theoretical and photovoltaic investigations. Also, it includes their structure-performance correlation study in detail. The devices co-sensitized with C1-4 displayed the superior photovoltaic performance when compared to NCSU-10 alone. The results ameliorate the role of efficient co-sensitizers to yield DSSC with improved performance. © 2018 Elsevier LtdItem Effects of substituents on the enrichment of the optical limiting action of novel imidazo[2,1-: B] [1,3,4]thiadiazole fused thiophene-based small molecules(Royal Society of Chemistry, 2019) Kakekochi, V.; Udayakumar, D.; Nikhil, P.P.; Chandrasekharan, K.The imidazo[2,1-b][1,3,4]thiadiazole (ITD) ring is a fused, planar aromatic heterocyclic system consisting of four heteroatoms with a bridgehead nitrogen atom. In this study, three new donor-acceptor-donor (D-A-D)-type organic molecules (ThITD1-ThITD3) were designed and synthesized, wherein ITD was an electron acceptor unit and the thiophene/phenyl moieties were electron donor units that produced a D-A-D configuration. The thiophene-ITD core structure comprises three different groups viz., thiophene-2-acetonitrile (ThITD1), phenylacetonitrile (ThITD2) and rhodanine-3-acetic acid (ThITD3), and the effect of substituents on the optical and electrochemical properties have been discussed based on structural modifications. The third-order nonlinear optical (NLO) properties analyzed by the Z-scan technique reveal that the molecules exhibit effective two photon absorption (TPA) with ThITD3 possessing substantially higher effective TPA coefficient (?eff) than ThITD1 and ThITD2, which is comparable to the reported ?eff values. The results unravel that ITD as an acceptor with an appropriate ?-linker will be a promising candidate for application in the field of optoelectronics/photonics. Herein, the thiophene-ITD ring system was explored for NLO applications and reported for the first time. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Effect of hydrophobic and hydrogen bonding interactions on the potency of ß-alanine analogs of G-protein coupled glucagon receptor inhibitors(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Venugopal, P.P.; Das, B.K.; Soorya, E.; Chakraborty, D.G-protein coupled glucagon receptors (GCGRs) play an important role in glucose homeostasis and pathophysiology of Type-II Diabetes Mellitus (T2DM). The allosteric pocket located at the trans-membrane domain of GCGR consists of hydrophobic (TM5) and hydrophilic (TM7) units. Hydrophobic interactions with the amino acid residues present at TM5, found to facilitate the favorable orientation of antagonist at GCGR allosteric pocket. A statistically robust and highly predictive 3D-QSAR model was developed using 58 ?-alanine based GCGR antagonists with significant variation in structure and potency profile. The correlation coefficient (R2) and cross-validation coefficient (Q2) of the developed model were found to be 0.9981 and 0.8253, respectively at the PLS factor of 8. The analysis of the favorable and unfavorable contribution of different structural features on the glucagon receptor antagonists was done by 3D-QSAR contour plots. Hydrophobic and hydrogen bonding interactions are found to be main dominating non-bonding interactions in docking studies. Presence of highest occupied molecular orbital (HOMO) in the polar part and lowest unoccupied molecular orbital (LUMO) in the hydrophobic part of antagonists leads to favorable protein-ligand interactions. Molecular mechanics/generalized born surface area (MM/GBSA) calculations showed that van der Waals and nonpolar solvation energy terms are crucial components for thermodynamically stable binding of the inhibitors. The binding free energy of highly potent compound was found to be ?63.475 kcal/mol; whereas the least active compound exhibited binding energy of ?41.097 kcal/mol. Further, five 100 ns molecular dynamics simulation (MD) simulations were done to confirm the stability of the inhibitor-receptor complex. Outcomes of the present study can serve as the basis for designing improved GCGR antagonists. © 2019 Wiley Periodicals, Inc.Item Resonance levels in GeTe thermoelectrics: Zinc as a new multifaceted dopant(Royal Society of Chemistry, 2020) Bhat, D.K.; Shenoy, U.S.Recently doping has been widely used in enhancing the thermoelectric properties of lead-free GeTe. But much of the work has been concentrated on carrier concentration tuning or phonon scattering. Until now, only indium has been reported to be the best resonant dopant in cubic GeTe. Herein, for the first time we introduce zinc as a resonant dopant to the cubic GeTe family. We show that zinc in GeTe not only introduces resonance states but also increases the band gap and raises the heavy hole valence band above the light hole valence band leading to enhanced Seebeck values. This multifunctional dopant incorporation in GeTe leads to enhanced transport properties as predicted by Boltzmann transport properties calculations based on first principles density functional theory electronic structure calculations. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Deciphering the competitive inhibition of dihydropteroate synthase by 8 marcaptoguanine analogs: enhanced potency in phenylsulfonyl fragments(Taylor and Francis Ltd., 2022) Das, B.K.; Chakraborty, D.The emergence of sulfa-drug resistance and reduced efficacy of pterin-based analogs towards Dihydropteroate synthase (DHPS) inhibition dictate a pressing need of developing novel antimicrobial agents for immune-compromised patients. Recently, a series of 8-Marcaptoguanin (8-MG) derivatives synthesized for 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (experimental KD ∼ 100–.0.36) showed remarkable homology with the pteroic-acid and serve as a template for product antagonism in DHPS. The present work integrates ligand-based drug discovery techniques with structure-based docking, enhanced MD simulation, and MM/PBSA techniques to demonstrate the essential features of 8-MG analogs which make it a potent inhibitor for DHPS. The delicate balance in hydrophilic, hydrophobic substitutions on the 8-MG core is the crucial signature for DHPS inhibition. It is found that the dynamic interactions of active compounds are mainly dominated by consistent hydrogen bonding network with Asp 96, Asn 115, Asp 185, Ser 222, Arg 255 and π-π stacking, π-cation interactions with Phe 190, Lys 221. Further, two new 8-MG compounds containing N-phenylacetamide (compound S1, ΔGbind-eff = –62.03 kJ/mol) and phenylsulfonyl (compound S3, ΔGbind-eff = −71.29 kJ/mol) fragments were found to be the most potent inhibitor of DHPS, which stabilize the flexible pABA binding loop, thereby increasing their binding affinity. MM/PBSA calculation shows electrostatic energy contribution to be the principal component in stabilizing the inhibitors in the binding pocket. This fact is further confirmed by the higher energy barrier obtained in umbrella sampling for this class of inhibitors. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Item A croconic acid-derived narrow band gap conjugated microporous polymer(Royal Society of Chemistry, 2023) Enoch, S.; Nipate, A.B.; Lakshmi, V.; Malakalapalli, R.R.Croconic acid, a novel highly electron-deficient building block, was introduced into a conjugated microporous polymer (CTPA). The CMP possesses strong donor-acceptor interactions, which resulted in near-IR absorption (red edge ∼1350 nm), a narrow bandgap (<1 eV) and high electrical conductivity upon doping (0.1 S m−1). Compared to the squaric acid congener (STPA), CTPA showed superior optical, electronic and electrical properties. © 2023 The Royal Society of Chemistry.