Photocytotoxicity and photoinduced phosphine ligand exchange in a Ru(ii) polypyridyl complex.

Two new tris-heteroleptic Ru(ii) complexes with triphenylphosphine (PPh) coordination, -[Ru(phen)(PPh)(CHCN)] (1a, phen = 1,10-phenanthroline) and -[Ru(biq)(phen)(PPh)(CHCN)] (2a, biq = 2,2'-biquinoline), were synthesized and characterized for photochemotherapeutic applications. Upon absorption of visible light, 1a exchanges a CHCN ligand for a solvent water molecule. Surprisingly, the steady-state irradiation of 2a followed by electronic absorption and NMR spectroscopies reveals the photosubstitution of the PPh ligand.