| 초록 |
Two isomeric N-heterocyclic carbene Ir(III) complexes, f-Ir-(dbfmi)3 and m-Ir-(dbfmi)3, were isolated and their systematic investigation on photophysical and electrochemical properties was carried out. Among them, the crystal structure of the meridional isomer, m-Ir-(dbfmi)3, is determined. Both isomers, f-Ir-(dbfmi)3 and m-Ir-(dbfmi)3, showed efficient emission in dichloromethane solution with quantum yields of 68% and 53%, respectively, due to unusual properties of the N-heterocyclic carbene (NHC) ligand; –that is, the complexes possess a strong metal–ligand bond that destabilizes the non-radiative metal centred ligand-field states. Depending on their configurations, the two isomers showed slightly different excited states. Even though both isomers possess a largely 3LC character mixed with the 3MLCT character in their excited states, m-Ir-(dbfmi)3 showed higher 3MLCT character as evidenced by the solvent polarity dependence emission spectra and emission lifetime. |
