Ultrafast Luminescence Decay in Rhenium(I) Complexes with Imidazo[4,5-f]-1,10-Phenanthroline Ligands: TDDFT Method

The interpretation of the ultrafast luminescence decay in [Re(Br(CO)3(N^N)] complexes as a new group of chromophoric imidazo[4,5-f]-1,10-phenanthroline ligands, including 1,2-dimethoxy benzene, tert-butyl benzene (L4) and 1,2,3-trimethoxy benzene, tert-butyl benzene (L6), was studied. Fac-[Re(Br(CO)3L4 and L6] with different aryl groups were calculated in singlet and triplet excited states. The calculations were performed in the gas phase and in the presence of chloroform as a solvent. The absorption and luminescence wavelengths, transition energy, and oscillator strength for singlet and triplet states were calculated for entitled complexes with L4 and L6 ligands. The UV-Vis spectrum and the singlet and triplet energy diagrams show a good agreement between our computational results and the experimental results, particularly in the case of a triplet state in chloroform. Spin-orbit coupling calculations show sufficient intensity and short wavelength in the UV-Vis absorption after SOC corrected absorption. The results of NBO calculations in the solvent show that rhenium acts as an acceptor by means of E(2), the second-order interaction energies between donor and acceptor orbitals, at the B3LYP/lanl2mb level of theory.