Synthesis, characterization, photophysics and intramolecular energy transfer process in bimetallic rhenium(I)–ruthenium(II) complexes

Two new heterobimetallic complexes of rhenium(I) and ruthenium(II) [(CO)3(NN)Re(4,4′-bpy)Ru(NN)2Cl](PF6)2 and already known monometallic complexes [Cl(NN)2Ru(4,4′-bpy)](PF6) and [(CO)3(NN)Re(4,4′-bpy)](PF6) and bimetallic complexes [Cl(NN)2Ru(4,4′-bpy)Ru(NN)2Cl](PF6)2, [(CO)3(NN)Re(4,4′-bpy)Re(NN)(CO)3](PF6)2 (NN = 2,2′-bipyridine, 1,10-phenanthroline; 4,4′-bpy = 4,4′-bipyridine) are synthesized and characterized by spectral techniques. The photophysical properties of all the complexes are studied. It is found that attachment of rhenium(I) altered the photophysical characteristics of ruthenium(II). Excited state energy transfer from the rhenium(I) chromophore to the ruthenium(II) is observed upon excitation at 355 nm.