Faculty Publications
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Item Catalytic oxidation of alcohols by nickel(II) Schiff base complexes containing triphenylphosphine in ionic liquid: An attempt towards green oxidation process(2010) Ramakrishna, D.; Badekai Ramachandra, B.; Karvembu, R.A series of square planar nickel(II) complexes containing N,O donor Schiff base ligand, i.e. N-(2-pyridyl)-N?-(5-substituted-salicylidene)hydrazine and triphenylphosphine, have been synthesized and characterized by analytical and spectral methods. Catalytic activities of all the complexes have been studied for the oxidation of alcohols in ionic liquid media using NaOCl as oxidant. © 2009 Elsevier B.V. All rights reserved.Item Third-order optical nonlinear studies of Cobalt (II) Schiff base complex bearing triphenylphosphine using Differential Optical Kerr Gate and Z-scan studies(2010) Rudresha, B.J.; Badekai Ramachandra, B.; Ramakrishna, D.; Anthony, J.K.; Rotermund, F.The third-order optical nonlinearity of the composite film of coordination complex [CoLPPh3Cl] (L = N-(2-pyridyl)-N?-(salicylidene)hydrazine) and PMMA has been investigated by using Differential Optical Kerr Gate (DOKG) and Z-scan measurements. Large value of the third-order nonlinear optical susceptibility (?(3)) of the order of 10-10 esu was measured and its nonlinear response time was found to be faster than or comparable to the laser pulse width (90 fs) used. The single beam Z-scan technique was used to investigate the nonlinear absorption property of the composite near 800 nm. The sample exhibit saturable absorption. The nonlinear absorption coefficient of sample is found to be -32 cm/GW. © 2010 Elsevier B.V. All rights reserved.Item Palladium-Schiff base-triphenylphosphine catalyzed oxidation of alcohols(2010) Dileep, R.; Badekai Ramachandra, B.Novel palladium(II)-N-(2-pyridyl)-N'-(5-R-salicylidene) hydrazine triphenylphosphine complexes were synthesized and characterized by UV, IR, 1HNMR and31P NMR spectral analysis, C, H, N analysis andmagnetic susceptibilitymeasurements. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of N-methyl-morpholine-Noxide as oxidant. The oxidation reactions were carried out in dichloromethane. A mechanistic study of the above reactions has been proposed. Copyright© 2010 JohnWiley & Sons, Ltd.Item Synthesis and characterization of schiff base metal complexes and reactivity studies with malemide epoxy resin(Korean Chemical Society sunlee@kcsnet.or.kr, 2012) Lakshmi, B.; Shivananda, K.N.; Prakash, G.A.; Isloor, A.M.; Mahendra, K.N.A novel malemide epoxy containing Co(II), Ni(II) and Cu(II) ions have been synthesized by curing malemide epoxy resin (MIEB-13) and Co(II), Ni(II) and Cu(II) complexes of macrocyclic bis-hydrazone Schiff base. The Schiff base was synthesized by reacting 1,4-dicarbnyl phenyl dihydrazide with 2,6-diformyl-4-methyl phenol. The Schiff base and its Co(II), Ni(II) and Cu(II) complexes have been characterized by elemental analyses, spectral (IR, 1H NMR, UV-vis., FAB mass, ESR), thermal and magnetic data. The curing reaction of maleimide epoxy compound with metal complexes was studied as curing agents. The stability of cured samples was studied by thermo-gravimetric analyses and which have excellent chemical (acid/alkali/solvent) and water absorption resistance. Further, the scanning electron microscopy (SEM) and definitional scanning colorimetric (DSC) techniques were confirmed the phase homogeneity of the cured systems.Item In vivo anticancer and histopathology studies of Schiff bases on Ehrlich ascitic carcinoma cells. 1st Cancer Update.(2013) Dhanya, D.; Isloor, A.M.; Shetty, P.; Nayak, P.G.; Pai, K.S.R.Three Schiff bases in two different concentrations were evaluated for their anti-tumor activity against Ehrlich ascites carcinoma (EAC) bearing Swiss albino mice. The in vivo anti-tumor potency of Schiff bases was assessed by measuring the increase in mean survival time of the drug treated over untreated control mice and treated standard (cisplatin) mice. Their toxicity was assessed in vivo in normal, standard, and EAC-bearing mice by measuring the drug-induced changes in biochemical as well as hematological parameters. The histopathology studies to assess the toxicity of these compounds on vital organs also have been studied. Among the three Schiff bases studied, 4-({[3-(4-fluorophenyl)-1. H-pyrazol-4-yl]methylene}amino)-5-[(2-methylphenoxy)methyl]-1,2,4-triazole-3-thiol (SB-3) at an optimal dose of 100. mg/kg body weight was found to enhance the mean survival time of infected mice. Deviated hematological parameters and mean survival time in tumor bearing mice were found to be significantly restored towards normal after treatment with SB-3 100. mg/kg body weight of mice. The ALP and SGOT values were found to approach the normal range. A:G ratios also did not deviate from normal on treatment with SB-3. The histopathology studies revealed only mild hepatotoxicity and nephrotoxicity when compared to the normal and standard. The splenic cellularity also did not show much variation from normal. SB-3 at a prime dose of 100. mg has shown promising anticancer activity in vivo against EAC when compared to standard drug with minimum toxic effects. © 2010 .Item Single-step oxidative homocoupling of aryl Grignard reagents via Co(II), Ni(II) and Cu(II) Complexes under air(John Wiley and Sons Ltd Southern Gate Chichester, West Sussex PO19 8SQ, 2014) Bhat, A.P.I.; Badekai Ramachandra, B.R.A simple catalytic system of direct synthesis for the symmetrical biaryls using catalytic amounts of Co(II), Ni(II) and Cu(II) complexes has been developed. The reaction system involves in situ synthesis of Grignard reagents. The complexes, containing bidentate Schiff base and dmit (2-thioxo-1,3-dithiole- 4,5-dithiolate) ligands, were compatible with diverse functionalities and afford a high yield of biaryls in a single step, proving to be promising catalysts in homocoupling reactions. Atmospheric oxygen is used as an oxidant which renders a green, simple and economical catalytic route. Copyright © 2014 John Wiley & Sons, Ltd.Item Immobilized magnetic nano catalyst for oxidation of alcohol(Elsevier, 2015) Bhat, P.B.; Rajarao, R.; Sahajwalla, V.; Badekai Ramachandra, B.R.Covalent attachment of Schiff base on magnetic nanoparticles yielded good selectivity for oxidation of alcohols. The ferromagnetic interaction in the complex added comprehensive advantage in enhancing the catalytic activity of the nanocatalyst. A greener approach for alcohol oxidation was achieved in solventless method with good yield (>78%). Leaching experiments confirmed a strong interaction between magnetic support and complex. The catalyst showed significant conversion even after 5 catalytic runs. © 2015 Elsevier B.V. All rights reserved.Item The hierarchies of hydrogen bonds in salts/cocrystals of isoniazid and its Schiff base - A case study(Royal Society of Chemistry, 2016) Oruganti, M.; Khade, P.; Das, U.K.; Trivedi, D.R.A series of two salts of isoniazid and two cocrystals of its Schiff base have been synthesised and characterized using FT-IR, 1H-NMR, DSC, XRPD and SCXRD. The crystal structures with 2,5-dihydroxybenzoic acid, 2,6-dihydroxy benzoic acid, 3-aminobenzoic acid and o-phthalic acid have been deduced. In all complexes the involvement of pyridine N (proton transfer/robust synthon) is noticed. The unit cell similarity index was calculated between two cocrystals (N-(propan-2-ylidene)isonicotinohydrazide)·(2,5-dihydroxybenzoic acid) and (3-aminobenozic acid)·(N-(propan-2-ylidene)isonicotinohydrazide). Furthermore, the index was compared with the reported complexes and it was found to be close to zero indicating isostructurality. The correlation between the NPyr-H?O (acid) hydrogen bond distance for the reported cocrystals and their corresponding pKa values has been deduced and validated. © The Royal Society of Chemistry 2016.Item Air-Stable Cobalt(II) and Nickel(II) Complexes with Schiff Base Ligand for Catalyzing Suzuki–Miyaura Cross-Coupling Reaction(Pleiades journals, 2018) Ansari, R.M.; Kumar, L.M.; Badekai Ramachandra, B.R.The Co(II) complex [Co{C6H4–1,2-(N=CH–C6H4O)2}] (I) and Ni(II) complex [Ni{C6H4–1,2-(N=CH–C6H4O)2}] (II) with Schiff base of o-phenylenediamine and salicylaldehyde have been synthesized. The structure of the ligand and its complexes were derived on the basis of various techniques such as elemental analysis, mass, FT-IR, electronic spectra and magnetic susceptibility. From the Singal crystal X-ray diffraction (SCXRD) analysis techniques (CIF file CCDC no. 1498772 (II)), it has been confirmed that the Schiff base ligand (L), coordinates to the metal ion in a tetradentate fashion through the nitrogen and oxygen atom. In addition, the square planar geometry of Ni(II) complex also has been confirmed from SCXRD. Electronic spectra, mass spectra, and magnetic susceptibility measurements reveal square planar geometry for the Co(II) complex. Synthesized complexes were used in cross-coupling of arylhalides with phenylboronic acid. The transformation offers products in good yields using 0.02 mmol catalysts loading, thereby proving the efficiency of the complexes as catalysts for Suzuki–Miyaura reaction. © 2018, Pleiades Publishing, Ltd.Item Photophysical and electrochemical properties of organic molecules: Solvatochromic effect and DFT studies(Elsevier B.V., 2018) Mohan, M.; Pangannaya, S.; Satyanarayan, M.N.; Trivedi, D.R.A series of five Schiff base molecules M1, M2, M3, M4 and M5 have been designed and synthesized by aldol condensation reaction. Synthesized molecules have been characterized by standard spectroscopic techniques in order to confirm their structural traits. The solvatochromic behavior of molecules M1 to M5 in solvents of varying polarity were investigated by UV–Vis, fluorescence spectroscopy and supported by TD-DFT calculations. DFT studies performed in the gas phase confirmed the energy stabilized structure of the molecules M1 to M5. Structural characteristics of molecule M2 favored higher fluorescence emission with a quantum yield of 0.35 and a solid-state emission of 512 nm. Fluorescence lifetime measurement of the molecules M1 to M5 exhibited a lifetime of order 2–5 ns. Overall, molecule M2 can find its application in organic light emitting diodes as a non-dopant emitter material. © 2018 Elsevier B.V.