1847 J. Indian Chem. Soc., Vol. 92, December 2015, pp. 1847-1853 Ruthenium-triphenylphosphine complex with pendent quinolyl Schiff base ligand : Synthesis, spectral characterization and catalytic property † Subhankar Kundu, Deblina Sarkar, Sujan Biswas, Subrata Jana and Tapan Kumar Mondal* Inorganic Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata-700 032, India E-mail : tkmondal@chemistry.jdvu.ac.in Abstract : The cis-(Cl)-[Ru(PMAQ)(PPh 3 )Cl 2 ] (1) (where, PMAQ = 8-{(2 -pyridylmethylene)amino}quinoline) complex has been synthesized and characterized by several spectroscopic techniques. The absorption and emission properties of the complex have been studied. Upon excitation in ILCT band at 331 nm, the complex exhibits emission at 475 nm. The emission decay profile has bi-exponential in nature with life time of 3.98 ns. The complex exhibits a quasi-reversible one electron Ru II /Ru III oxidation couple along with a ligand based reduction in cyclic voltammetric study. The redox properties are well supported by DFT data. The electronic structure of the complex has been interpreted by DFT method. The spin allowed electronic transitions computed by TDDFT method have a good agreement with the experimental spectrum of the complex. The complex efficiently catalyzes the oxidation of primary and secondary alcohols to the res- pective aldehydes and ketones with moderate to high conversions in presence of N-methylmorpholine-N-oxide (NMO) as co-oxidant. Keywords : Ruthenium triphenylphosphine complex, Schiff base ligand, electrochemistry, catalytic oxidation reaction, DFT calculation. Introduction The transition metal complexes with -acidic diimine (-N=C-C=N-) functional polypyridyl compounds show exciting photochemical and photophysical properties, and have applications in many technological fields 1 . The ex- cited states of these compounds are often sufficiently long- lived to become engaged in energy transfer reactions. Their electroluminescent properties have been applied in solar energy converters 2 and as electroluminescent mate- rials in OLED-type devices 3 . The compounds have been used as luminescent probes for long-range electron-trans- fer studies in proteins and other biomolecular systems 4 , and light-emitting electronic devices 5 . Transition metals catalyze a series of biological oxi- dation events including hydroxylation, epoxidation, dehalogenation, sulfoxidation, dehydrogenation, alcohol and aldehyde oxidations 6 . They also play important roles in the oxidative processes employed in chemical industry and laboratory synthesis 7 . Although the categories of the oxidation reactions may change from substrate to sub- strate, the late transition metal oxo moieties (M n+ =O) † In honour of Professor Animesh Chakravorty on the occasion of his 80th birth anniversary. have been proposed to serve as key and active intermedi- ates in most oxidation reactions 8 . With this view, in the past few decades there has been considerable interest in transition metal catalyzed oxidation of alcohols using oxi- dants such as molecular oxygen, iodosylbenzene, hydro- gen peroxide, tert -butyl hydroperoxide and N- methylmorpholine-N-oxide (NMO) 9 . In the past few years we have engaged to synthesis new ruthenium carbonyl and triphenylphosphine complexes with azoimine and diimine functional ligands and to ex- plore their catalytic activity towards oxidation of alco- hols 10 . In continuation, herein we have synthesized and characterized new ruthenium triphenylphosphine complex with NNN donor Schiff base ligand, 8-{(2-pyridyl- methylene)amino}quinoline (PMAQ). An array of spec- troscopic tools abetted with DFT calculation has been used to characterize the complex and to interpret the elec- tronic structure. The catalytic activity of the complex for the oxidation of primary and secondary alcohols to the respective aldehyde and ketones has been studied using N-methylmorpholine-N-oxide (NMO) as oxidizing agent. JICS-11