Polypyridine ruthenium(II) complexes containing mixed ligands. Synthesis, spectroscopic and photophysical and electrochemical properties

A series of polypyridine Ruthenium(II) complexes Ru(II) (ttp) (L)XxPF(6) were synthesized and characterized, where L are 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (dmpy), 1,10-phenanthroline(phen) and X are Cl-, NCS-, CN-; ttp = 4'-p-tolyl-2,2':6',2 "-terpyridine. Their redox, spectroscopic and photophysical properties have been studied. All complexes have intense MLCT (d(M)-->pi(L)*) absorbance at approximately 500 nm and were found to be emitting with monoexponential decay, of emission intensity at 298 K. The maximum wavelengths of absorbance and emission undergo a blue shift in the order of Cl-, NCS-, CN-. All complexes have an one-electron-oxidative process corresponding to Ru(III)/Ru(II) with a potential of about 0.8 V, and their oxidation potential increased also according to Cl-, NCS-, CN-. Two reversible or quasi-reversible one-electron-reductive processes based on ligands were also observed. (C) 1998 Elsevier Science Ltd.