Faculty Publications
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Item Synthesis, characterization and applications of metal complexes of 5-nitrosalicylidene 4-amino 3-mercapto-1, 2, 4-triazine- 5-one(2010) Ramasubramanian, A.S.; Badekai Ramachandra, B.; Ramakrishna, R.Transition metal complexes of Cu(II), Ni(II), Co(II) with 5- Nitro salicylidene 4- amino 3 -mercapto 1,2,4 triazine-5-one have been synthesized and characterized by analytical and spectral techniques. All metal complexes form ML type of complexes. Based on analytical data, IR spectra and magnetic moments Co (II), Ni (II) are assigned octahedral geometries while Cu (II) a square planar geometry. In all these complexes azomethine nitrogen, carbonyl oxygen and phenolic oxygen are involved in bond formation.Item Cobalt complexes in [EMIM]Cl - A catalyst for oxidation of alcohols to carbonyls(2010) Ramakrishna, R.; Badekai Ramachandra, B.A coordination complex system consisting of Cobalt (II)-Schiff bases with triphenylphosphine were synthesized and characterized. These catalysts were effective in the oxidation of primary and secondary alcohols. The oxidation reactions were carried out in ethyl-methyl-imidazolium ionic liquid in presence of NaOCl. Higher catalytic activity was observed for CoL1. © 2009 Elsevier B.V. All rights reserved.Item 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.Item Synthesis, characterization and catalytic activity of Fe(III) complexes containing Schiff base and triphenylphosphine ligands(2010) Rani, S.; Badekai Ramachandra, B.The oxidation of alcohols to carbonyls was investigated by an efficient catalyst system comprising of Fe(III)-Schiff base-triphenylphosphine complex. The complex chloroN-(2-mercaptophenyl)salicylideneiminebis(triphenylphosphine) iron(III) showed higher activity for oxidation of various alcohols under relatively mild conditions. © 2010 Elsevier B.V. All rights reserved.Item 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.Item Effective oxidation of alcohols by Iron(III)-Schiff base-triphenylphosphine complexes(2010) Rani, S.; Badekai Ramachandra, B.Iron(III)-Schiff base-triphenylphosphine complexes catalyze the oxidation of alcohols to their corresponding carbonyl compounds in presence of hydrogen peroxide in good yields. © 2010 Elsevier Ltd. All rights reserved.Item Transition metal complexes of 5-bromosalicylidene-4-amino-3-mercapto-1,2,4- triazine-5-one: Synthesis, characterization, catalytic and antibacterial studies(Serbian Chemical Society, 2011) Ramasubramanian, A.S.; Badekai Ramachandra, B.; Dileep, R.; Rani, S.Transition metal complexes of 5-bromosalicylidene-4-amino-3-mercapto-1,2,4- triazine-5-one with metal precursors, such as Cu(II), Ni(II), Co(II) and Pd(II), were synthesized and characterized by physico-chemical and spectroscopic techniques. All the complexes are of the ML type. Based on analytical, spectral data and magnetic moments, the Co(II) and Ni(II) complexes were assigned octahedral geometries, while the Cu (II) and Pd(II) complexes square planar. A study on the catalytic oxidation of benzyl alcohol, cyclohexanol, cinnamyl alcohol, 2-propanol and 2-methyl-1-propanol was performed with N-methylmorpholine-N-oxide (NMO) as co-oxidant. All the complexes and their parent organic moiety were screened for their biological activity on several pathogenic bacteria and were found to possess appreciable bactericidal properties. © 2011 Copyright (CC) SCS.Item Synthesis, characterization and in vitro cytotoxic properties of some new Schiff and Mannich bases in Hep G2 cells(Birkhauser Boston, 2011) Dhanya, D.; Isloor, A.M.; Shetty, P.; Chandrakantha, B.; Satyamoorthy, K.A series of 5-substituted-4-amino-3-mercapto- 1,2,4-triazoles were synthesized and were treated with various 3-substituted pyrazole aldehydes to obtain a series of new Schiff bases (3a-l). Few of the selected Schiff bases were converted into Mannich bases by reaction with diphenylamine/morpholine in presence of formaldehyde in ethanol media (4a-e, 5a-e). These newly synthesized compounds were characterized by elemental analysis, IR, NMR and mass spectrometry studies. A comparative study on the cytotoxic activities of few selected Schiff and Mannich bases was done in HepG2 cells using MTT assay. Few of the screened Schiff bases, 3a, 3d, 3e, 3g and 3h showed dose dependent cytotoxic activity, 3a being the most potent with an IC50 value of 0.018 g/l comparable to the standard drug doxorubicin. Among the Mannich bases, 5b was the most active with an IC50 value of 0.034 g/l. The Schiff bases were found to be more active, when compared to Mannich bases derived from them. The morpholine derived Mannich bases were more potent than those obtained from diphenyl amine. © Springer Science+Business Media, LLC 2010.Item 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.Item Rhodamine-based Cu2+-selective fluorosensor: Synthesis, mechanism, and application in living cells(2013) Sikdar, A.; Roy, S.; Haldar, K.; Sarkar, S.; Panja, S.S.A rhodamine B-based fluorescence probe (1) for the sensitive and selective detection of Cu2+ ion has been designed and synthesized using pyridine moiety. The optical properties of this compound have been investigated in acetonitrile-water binary solution (7:3 v/v). Compound 1 is found to be an excellent sensor for a biologically/physiologically very important transition metal ion (Cu2+) using only the two very different modes of measurements (absorption and emission); one case displayed intensity enhancement whereas in other case showed intensity depletion (quenching). A mechanistic investigation has been performed to explore the static nature of quenching process. The sensor has been found to be very effective in sensing Cu 2+ ion inside living cells also. © 2013 Springer Science+Business Media New York.