Faculty Publications

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Author: search.filters.author.Ramakrishna, D.

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Now showing 1 - 9 of 9
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    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.
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    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.
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    Effective oxidation of alcohols with H5IO6 catalyzed by nickel(II) schiff base complexes
    (2010) Ramakrishna, D.; Badekai Ramachandra, B.
    Nickel(II)-Schiff base-triphenylphosphine complexes catalyze oxidation of alcohols to carbonyls in presence of minimum amount of periodic acid. The catalytic oxidation was developed in mild conditions and showed good yields. The effects of temperature, time, and concentrations of catalyst and co-oxidant were studied. Higher catalytic activity has been observed for NiL1 compared to the other complexes.Copyright © Taylor & Francis Group, LLC.
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    Synthesis, characterization, and biological activity of metal complexes of 4-ethyl vanillideneamino-3-methyl-5-mercapto-1,2,4-triazole
    (2010) Ramasubramanian, A.S.; Badekai Ramachandra, B.; Ramakrishna, D.
    A series of transition metal-triazole derivatives have been synthesized and characterized by microanalytical, thermal, magneto-chemical, and spectral studies. The synthesized complexes were screened for biological activities. The complexes of Co(II) and Ni(II) emerged as a good antibacterial agent against Gram-negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Bacillus subtilis, and Shigella flexneri. © 2010 Taylor & Francis.
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    Green conversion of alcohols to carbonyls catalyzed by novel ruthenium-Schiff base-triphenylphosphine complexes
    (2011) Ramakrishna, D.; Badekai Ramachandra, B.
    A series of new RuII-Schiff base complexes of containing Ph 3P has been prepared and characterized. The complexes have been used as catalysts for the oxidation of alcohols in [EMIM]Cl ionic liquid-NaOCl system. Higher catalytic activity was found for RuL1. A plausible mechanism has been proposed. © 2010 Elsevier B.V. All rights reserved.
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    A catalytic process for the selective oxidation of alcohols by copper (II) complexes
    (2011) Ramakrishna, D.; Badekai Ramachandra, B.
    Novel copper (II)-N-(2-pyridyl)-N'-(5-R-salicylidene) hydrazine triphenylphosphine complexes have been synthesized and characterized. The complexes were effective in the catalytic oxidation of primary and secondary alcohols in presence of periodic acid (H5IO6) as oxidant. The oxidation reactions were carried out in acetonitrile. Electrochemical electron transfer study reveals CuII-CuI reduction in methanolic solutions. A mechanistic study of the above reactions has been proposed. © 2011 Elsevier B.V. All rights reserved.
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    Nonlinear optical study of palladium Schiff base complex using femtosecond differential optical Kerr gate and Z-scan techniques
    (2012) Rudresha, B.J.; Badekai Ramachandra, B.R.; Ramakrishna, D.; Anthony, J.K.; Lee, H.W.; Rotermund, F.
    A femtosecond differential optical Kerr gate (DOKG) and Z-scan techniques, have been applied to investigate the third-order optical nonlinearity of composite film of the coordination complex [PdLPPh 3] (L=N-(2-pyridyl)-N'-(salicylidene)hydrazine, PPh 3=triphenylphosphine) . Film exhibits superior nonlinear optical properties in the near-infrared spectral region. The nonlinear response time and third-order nonlinear optical susceptibility of complex were found to be?90 fs and 3.9×10 -10 esu, respectively. The Z-scan result shows that saturable absorption property of the film and its nonlinear absorption coefficient of the sample was found to be -23 cm/GW. © 2011 Elsevier Ltd. All rights reserved.
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    Cobalt complex in a room temperature ionic liquid: A convenient recyclable reagent for catalytic epoxidation of cyclic alkenes
    (Elsevier Masson SAS infos@masson.fr 62 rue Camille Desmoulins Issy les Moulineaux Cedex 92442, 2014) Ramakrishna, D.; Badekai Ramachandra, B.R.; Hanumanthappa, S.K.T.
    Co-catalyzed epoxidation of cyclic alkenes proceeds in ionic liquid media (1-ethyl-3-methylimidazolium hexafluorophosphate). Epoxidation of the alkenes to respective epoxides was greatly accelerated by the use of a cobalt-based catalyst in the presence of H2O2 as an oxidant. The catalyst in ionic liquid [Emim]PF6 was recycled and reused for about seven times. © 2014 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.
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    Thermally stable complexes of Fe(III), Co(II), Ni(II) and Cu(II) with Schiff base derived from 4-aminoacetophenone and salicylaldehyde
    (Springer, 2022) Ansari, R.M.; Ramakrishna, D.; Badekai Ramachandra, B.R.
    The Schiff base ligand 1-(4-((2-hydroxybenzylidene)amino)phenyl)ethan-1-one, obtained from 4-aminoacetophenone and salicylaldehyde, and its complexes with Fe(III), Co(II), Ni(II) and Cu(II) have been synthesized. These complexes were characterized by FTIR spectroscopy, elemental, and SCXRD analysis. FTIR spectra of complexes show the bidentate coordination of metal ions with ligands where O and N are electron-donating sites of the azomethine group. The electronic absorption spectra of these complexes show the characteristics of absorption bands involved in the Fe, Co, and Ni complexes due to their π→π*, n→π* transitions. Further, the geometry of the complexes was deduced from the calculated magnetic moment values and single crystal XRD analysis. Graphical abstract: A Schiff base derived from the condensation reaction between 2-aminoacetophenone and salicylaldehyde was involved in the formation of four different metal complexes, i.e., with Nickel, Cobalt, Iron, and Copper. The synthetic route to forming these complexes followed an easy process, and the complexes were obtained in good yields.[Figure not available: see fulltext.] © 2022, Indian Academy of Sciences.