DFT/TDDFT theoretical studies on electronic structures and spectral properties of rhenium(I) phenanthrolineimidazo complexes

► Four Re(I) metal complexes were investigated theoretically. ► LUMO energies decrease effectively much more than that of HOMO. ► Complex 4 with -COOCH3 groups has the smallest HOMO-LUMO energy gaps. ► The lowest lying absorption bands of these complexes all come from the HOMO-1 → LUMO transition.