Theoretical Study of Structure,Spectra and Quantum Efficiency for a Series of Iridium(Ⅲ)Complexes with the Cyclometalating Ligand
A series of cyclometalated iridium(Ⅲ)complexes[(C^N)2Ir(A^A)][C^N=ptaz(1,2,4),mhtz(3),ptaz=3,4,5-triphenyl-4H-1,2,4-triazole,mhtz=1,3-dimethyl-5-phenyl-1H-1,2,4-triazole;A^A=pzpy(1),npzpy(2,3),bicb(4),pzpy=2-(1H-pyrazol-1-yl)pyridine,npzpy=4-dimethylamino-2-(1H-pyrazol-1-yl)pyridine,bicb= 3,3′-methylenebis(1-methyl-1H-imidazole-3-ium2-ide)]was investigated theoretically to explore their structures,spectroscopic properties and quantum e ffi ciencies.The exploration of calculation methods shows that,the ground state structure optimized based on B3LYP functional and the excited state structure obtained by configuration interac-tion singles(CIS)method yield more accurate absorption and emission spectra.The lowest energy absorption and emission of complexes 1-4 at 408,376,382,365 nm and 503,506,468,511 nm,respectively.The HOMOs of complexes 1-4 are dominantly localized on the d(Ir)and π(C^N)ligand,while the LUMOs of complexes 1-3 are composed of π*(A^A)ligands,however,the LUMO of complex 4 resides on the π*(C^N)ligand.Therefore,the lowest energy absorption and emission of complex 4 exhibit mixed transition properties from metal to ligand and intra-ligand(MLCT/ILCT)that differ from complexes 1-3,the introduction of non-conjugated N^N ligands significantly weakens their contribution in the transition process.The quantum efficiency of complexes 1-4 depends on the magni-tude of the non-radiative rate constant knr,this is consistent with their contribution to reorganization energy of 4569 cm‒1(3)>2583 cm‒1(1)>1232 cm‒1(2)>975 cm‒1(4),this indicates that the size of the main-ligand and the conjuga-tion ability of the auxiliary ligand can both affect the phosphorescence quantum efficiency of these complexes.
万方数据
维普
