Photophysical properties of rhenium(I) diimine complexes: observation of room-temperature intraligand phosphorescence

Abstract

The luminescence behavior of the ligands 4-styryl-4{prime}-methyl-2,2{prime}-bipyridine (mstyb) and 1,4-bis(2-(4{prime}-methyl-2,2{prime}-bipyridyl-4-yl)ethenyl)benzene (dstyb) and the Re(I) complexes (Re(CO){sub 3}(CH{sub 3}CN)(mstyb))(PF{sub 6}) and (Re(CO){sub 3}-(CH{sub 3}CN)){sub 2}(dstyb)(PF{sub 6}){sub 2} is discussed. The dstyb ligand exhibits intense fluorescence at room temperature and in frozen (4:1 ethanol-methanol) solutions. The ligand mstyb does not emit at room temperature, but shows both fluorescence and phosphorescence in frozen solutions in the presence of 10% ethyl iodide. The Re(I) complex of mstyb emits from a {sup 3}MLCT excited state (558 nm) in room-temperature acetonitrile; however, in frozen solutions structured phosphorescence from an intraligand {sup 3}({pi} {yields} {pi}*) state (595 nm) is observed. The dinuclear Re(I) complex of dstyb exhibits structured intraligand phosphorescence (695 nm) in room-temperature solution and in low-temperature glasses.