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采用DFT/TDDFT方法研究了二米基硼B(Mes)_2基团修饰的一类Ir(ppy)_2(acac)配合物1~3的光物理性质.计算了电子结构,吸收和发射光谱以及自旋轨道耦合矩阵和辐射跃迁速率(k_r),探讨了取代基位置不同对磷光辐射和非辐射跃迁性质的影响.研究结果表明:向ppy配体的吡啶环引入B(Mes)_2基团,能够加强金属铱(Ir)与配体乙酰丙酮(acac)的相互作用,减小单-三重态能级差?E(S_1-T_1),提高系间窜跃速率和磷光辐射跃迁速率.向ppy配体的苯环引入B(Mes)_2基团则增大了S_0与T_1的结构变形和自旋轨道耦合矩阵 S_0 H_(SOC)T_1 ,使非辐射跃迁速率增加.B(Mes)_2基团位置异构,导致金属d轨道分裂方式不同,其在三个方向的自旋轨道耦合作用不同,辐射跃迁和非辐射跃迁都随之改变.从理论上解释了通过对ppy配体的吡啶环修饰可获得高磷光量子产率的原因.
The photophysical properties of a class of Ir (ppy) 2 (acac) complexes 1 ~ 3 modified with 2-m-2 B (Mes) 2 groups were studied by DFT / TDDFT method.The electronic structure, absorption and emission spectra, The spin-orbit coupling matrix and the radiative transition rate (k_r) were used to investigate the effect of different substituent positions on the properties of phosphorescent radiation and non-radiative transition. The results show that the introduction of B (Mes) _2 group can enhance the interaction between the metal iridium (Ir) and the acetylacetone (acac) ligand to reduce the single-triplet energy level difference E (S_1-T_1), improve the intersystem crossing rate and phosphorescence Radiation transition rate. The introduction of B (Mes) _2 group into the benzene ring of ppy ligand increased the structural deformation of S_0 and T_1 and the spin-orbit coupling matrix S_0 H_ (SOC) T_1, which increased the non-radiative transition rate. (Mes) _2 isomers, resulting in different d orbital splitting modes, which have different spin-orbit coupling effects in all three directions, and both the transition and non-radiative transitions will be changed.It is theoretically explained that ppy The reason for the high phosphorescence quantum yield obtained by the pyridine ring modification of ligands.