Faculty Publications
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Item Green conversion oxidation of alcohols using metal complexes: homogeneous catalysis(2020) Dileep, R.; Bhat, Badekai RamachandraItem Third-order nonlinear optical properties and optical switching of palladium (I) complex(2011) Manjunatha, K.B.; Dileep, R.; Shelar, M.S.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.R.We report the third-order nonlinear optical, optical power limiting and optical switching study of palladium-N-(2-pyridyl)-N′- (5-amino salicylidene) hydrazine triphenylphosphine, using Z-scan technique and pump-probe technique. The measured nonlinear refractive index is n 2=-6.022×10-9esu. The complex exhibits the reverse saturable absorption (RSA), the nonlinear absorption coefficient of β=10.748×10-9m/W. The good optical power limiting and optical switching behavior were observed in this complex. These suggest that this complex is a potential molecule for photonic applications. © 2011 American Institute of Physics.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 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 Thermal and antibacterial studies of novel lanthanide-schiff base complexes(2012) Ramasubramanian, A.S.; Badekai Ramachandra, B.R.; Dileep, R.Novel lanthanide complexes with the general formula [Ln(L)(ONO 2)(H 2O) 2] have been synthesized and characterized. {L = 5-bromosalicylidene 4-amino 3-mercapto-1,2,4-triazine-5-one (BrSAMT), Ln = La(III), Ce(III), (Pr(III) Eu(III), Sm(III), Nd(III), Tb(III), Dy(III), and Y(III)}. The thermal, magnetic, molar conductance, and spectral studies confirm that the ligand coordinates through sulfur, azomethine nitrogen, and phenolic oxygen. A scheme of thermal decomposition of the complexes is also proposed. La, Eu, and Yb complexes of BrSAMT show antibacterial activity against gram negative bacteria such as E. coli, Pseudomonas aeruginosa, Salmonella typhi, and Shigella flexneri. Copyright © Taylor & Francis Group, LLC.Item Nonlinear optical and all-optical switching studies of palladium(II) complex(2013) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Badekai Ramachandra, B.Palladium complex with Schiff-base (PdL) was synthesized and composite films were fabricated on glass substrates by the spin coating technique. Z-scan and degenerate four wave mixing (DFWM) studies on the complex were performed using Q-switched Nd:YAG 7 ns laser pulses at 532 nm to reveal the third-order nonlinear optical (NLO) parameters. The third-order NLO susceptibility (?(3)) and second-order hyperpolarizability (?h) in film form are estimated to be of the order of 10-11 and 10 -30 esu respectively. Large nonlinear absorption (NLA) due to reverse-saturable absorption (RSA) in the complex exhibits good optical power limiting (OPL) performance. All-optical switching (AOS) experiments were performed using the pump-probe method. The Z-scan investigations reveal that the switching is caused by excited-state absorption (ESA) of the He-Ne laser. © 2013 Elsevier B.V.Item Nonlinear optical and all-optical switching studies of novel ruthenium complex(2013) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Badekai Ramachandra, B.We report the experimental investigation on third-order nonlinear optical parameters of a novel (2-thioxo-1,3-dithiole-4,5-dithiolato) triphenylphosphine Ru (III) [RuL] both in solution and solid form, by using Z-scan technique at the measurement wavelength of 532 nm. The films were prepared by spin-coating technique on glass substrate. The magnitude and sign of the third-order nonlinear absorption and refractive index n2 of ruthenium complex were determined. The results reveal that ruthenium complex exhibits large negative nonlinear refractive index (n2) of the order of 10 -9 esu. The third-order nonlinear optical susceptibility (?(3)) values were of the order 10-10 esu. The nonlinear optical properties were found to vary with concentration. The ?(3) value is confirmed through degenerate four wave mixing (DFWM) experiment at the same wavelength. The effective excited-state absorption cross section was found to be larger than the ground state absorption cross section indicating that the operating nonlinear mechanism is reverse saturable absorption (RSA). It was found that the ruthenium complex exhibits good optical power limiting and also all-optical switching of nanosecond laser pulses. This new compound has potential application as photonic and optoelectronic devices. © 2013 Elsevier Ltd.Item Third-order nonlinear optical, optical power limiting, and all-optical switching studies on palladium complexes(2014) Manjunatha, K.B.; Shelar, V.M.; Dileep, R.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.The authors report the third-order nonlinear optical properties of two palladium complexes in solution and film form using nanosecond Z-scan technique at 532 nm. The nonlinear refractive index n2of the investigated complexes is found to be negative. Both complexes exhibit strong reverse saturation absorption and show good optical power limiting of nanosecond pulses. Also the third-order nonlinear optical susceptibility of the complexes was determined using degenerate four-wave mixing technique. The variations of nonlinear response on donor and acceptor type of units present in the complexes are studied. The all-optical switching phenomenon was also demonstrated by using nanosecond pump-probe technique. © 2014 Copyright Taylor and Francis Group, LLC.Item Palladium complex in a room temperature ionic liquid: A convenient recyclable reagent for catalytic oxidation(Taylor and Francis Ltd., 2014) Dileep, R.; Badekai Ramachandra, B.; Suresha Kumara, T.H.S.Palladium (Pd)-catalyzed carbonylation of alcohols proceeds in ionic liquid (IL) media (1-ethyl-3-methylimidazolium hexafluorophosphate). Carbonylation of primary/secondary alcohols to aldehydes/ketones was greatly accelerated by the use of a Pd-based catalyst in the presence of NaOCl as an oxidant. The catalyst was more easier to recycle in the IL [Emim]PF6 with an equal-proportioned CH2Cl2 than in the single CH2Cl2 or IL. © 2014 The Author(s). Published by Taylor & Francis.Item All optical nonlinear and switching characteristics of a novel ruthenium complex(Elsevier B.V., 2014) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.Third-order nonlinear optical properties of a novel ruthenium complex (2-thioxo-1,3-dithiole-4,5-dithiolato) triphenylarsenic Ru(III), have been investigated by employing Z-scan and DFWM techniques. The compound shows self-defocusing effect. Its nonlinear refractive index, third-order nonlinear optical susceptibility and the second-order hyperpolarizability are seen to be of the order of 10-9, 10-10 and 10-30 esu respectively. The nonlinear absorption coefficient is of the order of 10 -9 m/W. This material exhibits good optical power limiting capability which is seen to occur due to reverse saturable absorption. Experiments on all-optical switching action indicate that the sample can function as an optical inverter or a NOT gate. © 2014 Elsevier B.V. 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