Abstract:

Anthracene vinyl mononuclear ruthenium isomeric complexes 1 and 2 were synthesized from 9-ethynylanthracene and 2-ethynylanthracene, carbonylchlorohydridotris(triphenylphosphine) ruthenium(Ⅱ)[RuHCl(CO)(PPh₃)₃] and trimethylphosphine(PMe₃) for ligand exchange, The structure of complex 2 was further confirmed by X-ray single crystal diffraction. Their electrical and optical properties were investigated in combination with theoretical calculations. Electronic structures of complexes 1 and 2 from density functional theory(DFT) optimization show that ruthenium vinyl and anthracene ring have different configurations in two isomers. Frontier molecular orbitals from DFT calculations feature that electron delocalized over the whole molecule in HOMO, and with larger proportion(90%) in anthracene vinyl parts. This suggests that anthracene vinyl ligand mainly participate in redox process. Electrochemical studies indicate that redox reversibility of complex 1 is lower than that of complex 2. Electronic absorption spectra of complexes 1, 2 and precursor molecules 1b, 2b exhibit obvious changes. The absorptions in UV region of complexes 1 and 2 collapse in comparison with that of molecules 1b and 2b, and appear a weak and broad absorptions in long wavelength direction, which are assigned to π→π^* and metal-to-ligand charge-transfer(MLCT) absorptions from highest occupied molecular orbital(HOMO)→lower unoccupied molecular orbital(LUMO) transitions by time-dependent DFT(TDDFT) calculation. The fluorescence emission spectrum reveals that fluorescence intensity and fluorescence quantum yields drop sharply after the ruthenium coordinate to anthracene vinyl. CCDC of complex 2:1488284.

Key words: anthracene vinyl, monoruthenium complex, electrochemistry, spectrum properties, density functional theory and time-dependent density functional theory calculations