Theoretical study on photophysical properties of cyclometalated cationic iridium(III) complexes containing dipyrido[3,2-f:2',3/-h]quinoxaline ligand

摘要

We report a theoretical analysis of a family of cyclometalated cationic iridium(III) complexes: [Ir(CN)_2(NN)]~+ [NN = dipyrido[3,2-f:2',3'-h]quinoxaline(dpq), HCN = 1-phenylpyrazole(Hppz) (1); HCN = 7,8-benzoquinoline(Hbzq) (2); HCN = 2-phenylquinoline(Hpq) (3); HCN = 1-(2,4-diflourophenyl) pyrazole(Hdfppz) (4), HCN=l-(2,4-dimethylphenyl) pyrazole(Hdmppz) (5), HCN = l-(2,4-diflourophenyl)-1,2,4-triazole(Hdfptz) (6)] by using density functional theory (DFT) method to investigate their optoelectronic properties and understand the phosphorescent efficiency mechanism. Complexes 1-3 exhibit green to yellow luminescence. The different quantum efficiencies of 1-3 in methanol (MeOH), acetonitrile (CH_3CN), and dichloromethane (CH2Cl_2) solvents have been explained by calculated results. Complexes 4 and 5 show different trend in the absorption and emission spectra comparing with 1 due to the added different substituent on the phenyl of ppzH. The emission wavelength of the assumed complex 6 bearing the triazole in CN ligand is blue-shifted to the blue region. We suggest complex 6 might be a potential candidate as blue-emitting material.