Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Ethyl 1-(2,4-dichlorobenzyl)-4-oxo-7-trifluoromethyl-1,4-dihydroquinoline- 3-carboxyl-ate(2012) Fun, H.-K.; Ooi, C.W.; Garudachari, B.; Isloor, A.M.; Hegde, G.In the title compound, C 20H 14Cl 2F 3NO 3, the trifluromethyl group is disordered over two sets of sites in a 0.784 (10):0.216 (10) ratio. The quinoline ring system is essentially planar with a maximum deviation of 0.058 (2) Å for the N atom and forms dihedral angles of 89.23 (11) and 8.13 (17)°, respectively with the mean planes of the benzene ring and the carboxylate group. In the crystal, pairs of weak C - H?O and C - H?F hydrogen bonds link molecules into centrosymmetric dimers. The crystal structure is further stabilized by weak ?-? [centroid-centroid distance = 3.624 (2) Å] interactions.Item 2-(8-Bromoimidazo[1,2-a]pyridin-2-yl)-N?-[(E)-4-diethylamino-2- hydroxybenzyl-idene]acetohydrazide dihydrate(2012) Fun, H.-K.; Loh, W.-S.; Shenvi, S.S.; Isloor, A.M.; Hegde, G.In the title compound, C 20H 22BrN 5O 2·2H 2O, the Schiff base mol-ecule exists in an E conformation with respect to the acyclic C=N bond. An S(6) ring motif is formed via an intra-molecular O - H?N hydrogen bond. The dihedral angle between the imidazo[1,2-a]pyridine system and the benzene ring is 84.62 (5)°. In the crystal, N - H?O, O - H?O, O - H?N, C - H?O and C - H?Br hydrogen bonds link the mol-ecules into a three-dimensional network. The crystal packing is further stabilized by C - H?? and ?-? inter-actions [centroid-centroid distance = 3.5365 (7) Å].Item Synthesis, characterization and antimicrobial studies of some new quinoline incorporated benzimidazole derivatives(2012) Garudachari, B.; Satyanarayana, M.N.; Thippeswamy, B.; Shivakumar, C.K.; Shivananda, K.N.; Hegde, G.; Isloor, A.M.Two new series of quinoline incorporated benzimidazole derivatives (4a-i and 8a-f) were synthesized from substituted aniline and isatin through multi-step reaction. 6-substituted-4-carboxyquinolines (3a,b and 7) were synthesized by multi component one pot reactions (via Doebner reaction and Pfitzinger reaction respectively) and the targeted benzimidazole derivatives were obtained by the reaction of 6-substituted-4-carboxyquinolines (3a,b and 7) with substituted aromatic diamines in acidic media. All the newly synthesized compounds were characterized by IR, NMR mass spectral study and also by C, H, N analyses. The final compounds were screened for their in-vitro antibacterial and antifungal activity by well plate method (zone of inhibition). The results revealed that, compounds 4c, 4d, 8c and 8d showed significant antibacterial activity. The compound 8b was found to be potent antifungal agent. 4a, 8a and 8f showed moderate to good antimicrobial activity as compared to the standard drugs against all tested microbial strains. © 2012 Elsevier Masson SAS. All rights reserved.Item Synthesis and biological evaluation of novel substituted 1,3,4-thiadiazole and 2,6-di aryl substituted imidazo [2,1-b] [1,3,4] thiadiazole derivatives(Elsevier Masson s.r.l., 2014) Chandrakantha, B.; Isloor, A.M.; Shetty, P.; Fun, H.-K.; Hegde, G.A new series of N-[5-(4-(alkyl/aryl)-3-nitro-phenyl)-[1,3,4-thiadiazol-2- yl]-2,2-dimethyl-propionamide 4 (a-l) and 6-(4-Methoxy-phenyl)-2-(4-alkyl/aryl)- 3-nitro-phenyl)-Imidazo [2,1-b] [1,3,4] thiadiazole 6 (a-l) were synthesized starting from 5-(4-Fluoro-3-nitro-phenyl)-[1,3,4] thiadiazole-2-ylamine. The synthesized compounds were characterized by IR, NMR, mass spectral and elemental analysis. All the compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by well plate method (zone of inhibition). Compounds 4a, 4c and 6e, 6g displayed appreciable activity at the concentration 0.5-1.0 mg/mL.© 2013 Elsevier Masson SAS. All rights reserved.Item Click chemistry approach: Regioselective one-pot synthesis of some new 8-trifluoromethylquinoline based 1,2,3-triazoles as potent antimicrobial agents(2014) Garudachari, B.; Isloor, A.M.; Satyanarayana, M.N.; Fun, H.-K.; Hegde, G.Three series of 8-trifluoromethylquinoline based 1,2,3-triazoles derivatives (5a-c, 6a-d and 7a-c) were synthesized by multi-step reactions by click chemistry approach. Synthesized compounds were characterized by spectral studies and X-ray analysis. The final compounds were screened for their in-vitro antimicrobial activity by well plate method (zone of inhibition). Compounds 5c, 6b, 8b, 11 and 12 were found to be active against tested microbial strains. The results are summarized in Tables 5 and 6. © 2014 Elsevier Ltd. All rights reserved.Item Stable configurations of graphene on silicon(Elsevier B.V., 2017) Javvaji, B.; Shenoy, B.M.; Roy Mahapatra, D.R.; Ravikumar, A.; Hegde, G.; Rizwan, M.R.Integration of graphene on silicon-based nanostructures is crucial in advancing graphene based nanoelectronic device technologies. The present paper provides a new insight on the combined effect of graphene structure and silicon (001) substrate on their two-dimensional anisotropic interface. Molecular dynamics simulations involving the sub-nanoscale interface reveal a most favourable set of temperature independent orientations of the monolayer graphene sheet with an angle of ?15° between its armchair direction and [010] axis of the silicon substrate. While computing the favorable stable orientations, both the translation and the rotational vibrations of graphene are included. The possible interactions between the graphene atoms and the silicon atoms are identified from their coordination. Graphene sheet shows maximum bonding density with bond length 0.195 nm and minimum bond energy when interfaced with silicon substrate at 15° orientation. Local deformation analysis reveals probability distribution with maximum strain levels of 0.134, 0.047 and 0.029 for 900 K, 300 K and 100 K, respectively in silicon surface for 15° oriented graphene whereas the maximum probable strain in graphene is about 0.041 irrespective of temperature. Silicon–silicon dimer formation is changed due to silicon–carbon bonding. These results may help further in band structure engineering of silicon–graphene lattice. © 2017 Elsevier B.V.Item Transient dynamic distributed strain sensing using photonic crystal waveguides(OSA - The Optical Society info@osa.org, 2017) Hosangadi Prutvi, H.P.; Mahalingam, V.; Roy Mahapatra, D.R.; Hegde, G.; Hanagud, S.; Rahman, M.R.This paper presents a new type of one-dimensional photonic crystal (PC) waveguide sensor and a technique for prediction of transient strain response accurately. The PC waveguide is integrated on a silicon substrate. We investigate the effect of non-uniform strain localization on the optical signal and use that information to capture the transient strain. Wavelength shift due to distributed strain field is modeled by incorporating the mechanically deformed geometry and photo-acoustic coupling through Pockels effect in a finite element formulation. We demonstrate the advantages of using our proposed method, where multiple spectral peak shift is used instead of single peak shift in order to improve sensing output accuracy and also to estimate the sensor parameter regressively, where the signal’s bandwidth is limited. The maximum sensitivity of the waveguide sensor in terms of wavelength shift is estimated to be 0.36 pm/?strain in single-peak-based sensing, whereas the proposed adaptive multispectral estimation scheme shows an enhanced sensitivity of 4.029 pm/?strain. © 2017 Optical Society of America.Item Morphology controlled n-type TiO2 and stoichiometry adjusted p-type Cu2ZnSnS4 thin films for photovoltaic applications(American Chemical Society, 2017) Varadharajaperumal, S.; Sripan, C.; Ganesan, R.; Hegde, G.; Satyanarayana, M.N.This paper presents the fabrication and characterization of stoichiometry adjusted Cu2Zn1.5Sn1.2S4.4 thin film (FTO/TiO2/CdS/CZTS/Au) photovoltaic (PV) devices. The PV devices were developed using the window layer of rutile TiO2 nanoarchitecture arrays, i.e., one-dimensional (1D) nanorods and three-dimensional (3D) combined/ hierarchical structures (nanorods with microspheres). Onedimensional (1D) nanorods and 3D combined structures of TiO2 window layers were synthesized by a hydrothermal method with different solvents without any assistance of surfactants and templates. We achieved two kinds of TiO2 nanostructures by tuning the precursor concentrations and volume by keeping a constant growth time and temperature. The detailed structural properties were studied using X-ray diffraction and high resolution transmission electron microscopy. Phase formation and chemical state of the prepared samples were examined by Raman spectroscopy and X-ray photoelectron spectroscopy. The surface morphology and luminescence studies of TiO2 nanostructures were analyzed using field emission scanning electron microscopy and cathodoluminescence techniques. The current-voltage performance of fabricated devices were measured under an AM 1.5 solar simulator. It is observed that combined structure PV device shows better efficiency (1.45%) than the nanorods alone structure (0.55%). Present work is a first attempt made to construct the inverted CZTS based solar cells. This study establishes the window layer of hierarchical TiO2 nanostructures based morphology that offers a great potential for the development of high-efficiency nonstoichiometric CZTS based solar cells. © 2017 American Chemical Society.Item Effect of CuPc and PEDOT:PSS as hole transport layers in planar heterojunction CdS/CdTe solar cell(Institute of Physics Publishing helen.craven@iop.org, 2019) Varadharajaperumal, S.; Ilango, M.S.; Hegde, G.; Satyanarayan, M.N.This paper presents the fabrication and photovoltaic performance of new architecture based planar heterojunction CdS/CdTe thin film solar cells which were employed with two hole transport layers (PEDOT:PSS as HTL1 and CuPc as HTL2). The reported solar cells were fabricated through various deposition techniques such as sputtering, thermal evaporation, spin coating and characterized by FESEM, AFM, XPS, UPS and AM 1.5 solar simulator. The interfacial layer growth and chemical state identification of the deposited thin films were studied by cross-sectional FESEM and XPS techniques. The band bending occurs between absorbing and transporting layer helps to inject the excited charge carriers effectively into electrode that was explained using UPS analysis. The present work intends to explain the role of additional window layer (TiO2), buffer layer (CdS) and hole transporting layers (PEDOT:PSS and CuPc) in the novel device architecture. Further, these findings will offer new research directions to address the double hole transport (back contact) layers selection concept in CdS/CdTe heterojunction based solar cells. © 2019 IOP Publishing Ltd.Item Controlled growth of 1D-ZnO nanotubes using one-step hot plate technique for CZTS heterojunction solar cells(Elsevier Ltd, 2020) Varadharajaperumal, S.; Alagarasan, D.; Ganesan, R.; Satyanarayan, M.N.; Hegde, G.Present work reports a simple, rapid, one-step hot plate technique for systematic growth transformation of highly oriented ZnO nanorods (ZNRs) into ZnO nanotubes (ZNTs). The controlled growth of ZnO nanostructures (nanorods and nanotubes) was achieved at low temperature (90 °C) in a short time (1hr) in a sealed weighing bottle (100 ml). It is observed that as the Zinc precursor concentration increases, a vertically grown ZnR morphology evolves into ZNT. The crystal structure of as-grown ZnO nanostructures, surface morphology, phase, and optical energy gap were respectively characterized by XRD, FESEM, Raman, XPS, CL and UV–Vis spectroscopy. Grown nanostructures are further explored for their application in CZTS based heterojunction photovoltaics. © 2019