Synthesis, spectroscopic, and DFT studies of rhenium(І) complexes with phenanthrolineimidazo ligands containing thienyl moieties

A rhenium(I)–tricarbonyl complex [Re(CO)3(L)Cl] (L = 2-(3-thienyl)imidazo[4,5-f][1,10]-phenanthroline; TIMPhen–Re) was successfully synthesized. UV–Vis absorption, fluorescence spectrometry, and cyclic voltammetry were used to investigate the photophysical properties of the complex. The geometrical structures of the ground state and the absorption spectral properties of TIMPhen–Re were determined using density functional theory and time-dependent density functional theory. The lowest-lying singlet → singlet absorption band of TIMPhen–Re, corresponding to the prominent absorption peak at 415 nm observed in the experiments, was assigned to the pure highest occupied molecular orbital → lowest unoccupied molecular orbital transition. The calculated ionization potential and electron affinity show that TIMPhen–Re possesses good hole-transfer abilities, and the balanced transport of electrons and holes is compared with that of its analog Phen–Re.