Browsing by Author "Ramakrishna, R."

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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.
Study of third-order nonlinear optical and all-optical switching properties of palladium metal-organic complex
(Elsevier B.V., 2013) Manjunatha, K.B.; Ramakrishna, R.; Umesh, G.; Badekai Ramachandra, B.
We report the results of studies on third-order nonlinear optical properties of a newly synthesized palladium metal-organic complex [PdLPPh 3] (L = N-(2-pyridyl)-N?-(5-chlorosalicylidene)hydrazine) both in film and solution form using Z-scan and degenerate four wave mixing (DFWM) techniques. Experiments were performed using Q-switched Nd: YAG laser with nanosecond pulses at 532 nm. Investigations revealed that the palladium metal-organic complex possesses nonlinear absorption coefficient ?eff which is of the order of 10-9 m/W due to reverse saturable absorption (RSA) and negative nonlinear refractive index (self-defocusing) n2 which is of the order of 10-9 esu. The real and imaginary parts of the third-order nonlinear optical susceptibility (?(3)) were found to be of the order of 10-11 esu. The second-order hyperpolarizability (?h) was estimated to be of the order of 10-30 esu. The results of pump-probe experiments show that the switch-on and switch-off times of the palladium metal-organic complex were in ?s for different pump intensities and the energy dependent transmission studies reveal better limiting property of the compound at nanosecond regime. Thus the nonlinear response of the material suggests that it has a potential application for high sensitive photonic devices. © 2013 Elsevier B.V. All rights reserved.
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.