Nanosecond transient absorption spectroscopy of a Ru polypyridine phenothiazine dyad.

A bipyridine phenothiazine ligand [(PTZEtv 2 bpy) and metal complexes [Ru(Ph 2 phen) 3 ] 2+ ( 1 ), [(Ph 2 phen) 2 Ru(PTZEtv 2 bpy)] 2+ ( 2 ), and [(PTZEtv 2 bpy)(Ph 2 phen)Ru(dpp)] 2+ ( 3 ) were synthesized and characterized, where Ph 2 phen is 4,7-diphenyl-1,10-phenanthroline, dpp is 2,3-bis(2-pyridyl)pyrazine and PTZEtv 2 bpy is 4,4′ ethylene bridged phenothiazine 2,2′bipyridine. The reduction potentials of PTZEtv 2 bpy, 1 , 2 , and 3 were determined by cyclic and square wave voltammetric methods. The absorbance and emission spectra of complexes 2 and 3 yield intense, visible Metal-to-Ligand Charge Transfer (MLCT) transitions. The nanosecond transient absorption data indicate formation of both the 3 MLCT state and a ligand localized 3 PTZ state. [ABSTRACT FROM AUTHOR]