A rhenium(I) complex with indolyl-containing ligand: Synthesis, photophysical properties and theoretical studies

A rhenium(І) tricarbonyl complex, [Re(CO)3(IDIMPhen)Cl] (IDIMPhen-Re) [where IDIMPhen = 2-(3-indolyl)-imidazo[4,5-f]-[1,10]phenanthroline], have been successfully synthesized and fully characterized by 1H NMR, 13C NMR, IR, GC–MS, elemental analysis, UV–Vis and cyclic voltammetry (CV). Meanwhile, the electronic structure and spectroscopic features of IDIMPhen-Re have been investigated using the density functional theory (DFT) and time-dependent DFT methods. Based on the calculated results, the experiment data are explained in great detail. The calculated orbital energies of the HOMO and LUMO of IDIMPhen-Re are in reasonable agreement with those obtained from the electrochemical measurements. The lowest lying singlet → singlet absorption band of IDIMPhen-Re, corresponding to the prominent absorption peak at 447 nm observed in experiments, should be assigned to the pure HOMO → LUMO transition. The calculated IP and EA show that IDIMPhen-Re possesses the good hole-transfer ability and the balanced transport of electrons and holes is more accessible compared with its analogue Phen-Re.