Copper(I) complexes of phenanthrolineimidazole ligands: structures, photophysical properties, and quantum chemical studies

Three copper(I) complexes, [Cu(PimP)(POP)]PF 6 ( 1 ), [Cu(NimP)(POP)]PF 6 ( 2 ), and [Cu(AimP)(POP)]PF 6 ( 3 ) (PimP = 2-phenyl-1 H -imidazo[4,5-f][1,10]phenanthroline, NimP = 2-(2-naphthyl-1 H -imidazo[4,5-f]phenanthroline, AimP = 2-(9-anthryl)-1 H -imidazo[4,5-f]phenanthroline, POP = bis[2-diphenylphosphino]-phenyl)ether) have been synthesized and characterized. Investigations into the effects of the varying substituents on the structural, absorption, and emission characteristics of the corresponding complexes are presented. Complexes 1 and 2 exhibit similar photophysical properties with the weaker lowest lying MLCT absorption at λ  > 400 nm and the phosphorescence 3 MLCT/ 3 LLCT emission in the range of 570–590 nm, whereas complex 3 shows different absorption and emission properties, in which the LLCT absorption band is overlapped with the structured absorption bands belonging to the characteristic peaks of the anthracene moiety, and the emitting excited state is described as the 3 LLCT character. Density functional theory and time-dependent density functional theory calculations were employed to rationalize the photophysical properties of the complexes.