Electronic structure and properties of a new series of fac-Re(I) tricarbonylcomplexes: a DFT study

Luminescence of rhenium(I) tricarbonyl diimine complexes was first reported by Wrightonand Morse in ۱۹۷۴ [۱]. Since the first report, syntheses, photochemistry and photophysics of fac-[Re(Cl)(CO)۳(α-diimine)] complexes have been widely studied. These complexes have beenreported as promising materials for potential applications in catalysis, sensors, organic lightemittingdiodes, solar energy conversion, photosensitizers and possible agents in bioimaging andcancer therapy [۲,۳]. Structural modification of α-diimine ligand broadly affects the characterand energy of HOMO and LUMO in these complexes [۴]. Electron donor-acceptor (D-A)systems have been extensively investigated in recent years. To realize high performancephotocatalysis in the multichromophore ensembles, controlling the charge transfer (CT) processis essential [۵]. Depending on the energy levels of the metal and ligand orbitals, different excitedstates, including MLCT, LLCT, IL and SBLCT can be generated. In this research work,electronic structure of four fac-[Re(Cl)(CO)۳(α-diimine)] complexes with electron acceptoracceptorand donor-acceptor substituted α-diimine ligands are studied by DFT method.Benzothiazole derivatives (as electron acceptor) and triphenylamine groups (as electron donor)were introduced to the α-diimine core. The effect of donor and acceptor groups on the characterand energy of HOMO and LUMO will be discussed in details. Moreover, TDDFT calculationsresults will be investigated to understand the electronic spectra and excited states of thecomplexes.