8-羟基喹啉锰配合物电子结构和光谱性质的含时密度泛函研究

采用密度泛函理论(DFT)B3LYP方法, 对8-羟基喹啉锰配合物进行结构优化, 探讨了配合物的结构、分子轨道能级和组成、电荷分布和转移等; 采用含时密度泛函理论(TDDFT)B3LYP/6-31G(d,p)方法对配合物的电子结构进行计算, 获得其吸收光谱. 结果表明, Mn(Ⅲ)与8-羟基喹啉中的N原子和O原子形成不对称六配位的稳定配合物, 金属锰对前线轨道的贡献很大, 在HOMO轨道中占28.53%, 在LUMO轨道中占68.30%; 中心金属锰(Ⅲ)强烈地参与发光, 电子在基态与激发态之间的跃迁, 主要是中心金属锰及8-羟基喹啉配体间的电荷转移, 在可见光区存在2个强度较大的吸收峰, 分别位于756.8 nm和532.7 nm处. 通过对双分子体系的研究发现, 相邻2个分子之间能够进行微量电荷的转移, 分子间的相互作用对前线轨道组成有明显的影响.

TD-DFT Study on Electronic Structure and Spectrum Properties of 8-Hydroxyquinolinato Manganese Complex

The structure and electronic properties of 8-hydroxyquinolinato manganese(Ⅲ) complex(MnQ3, Q=8-hydroxyquinolinato) were studied theoretically with density functional theory(DFT). The structure was optimized and the calculation results show that the manganese ion is coordinated with one nitrogen atom and one oxygen atom of 8-hydroxyquinolinato ligand. The average bond length of Mn—N is 0.2072 nm and that of Mn—O is 0.1887 nm, which were consistent with the crystallographic data. In addition, the molecular structure and electronic structural characteristics of the complex were analyzed. The contribution of Mn(Ⅲ) to the frontier molecular orbitals are significant, 28.53% to HOMO and 68.30% to LUMO. The electro-absorption spectrum of MnQ3 was calculated by time-dependent density functional theory, the calculated results show that the two strong absorption peaks are at 756.8 nm and 532.7 nm respectively due to the charge transformation from intra-ligand to manganese(Ⅲ). From two-molecule system, the charge was transported from one complex to the neighbor one. The intermolecular interaction affects the composition of the frontier molecular orbital obviously.