邻硝基苯甲醛缩对乙酰基苯胺希夫碱的结构与光谱的理论研究

利用实验方法测定了标题化合物的紫外吸收光谱、荧光发射光谱和相对荧光量子产率，结果表明该化合物具有较强的荧光性质。采用密度泛函理论(density functional theory, DFT)中的杂化密度泛函B3LYP方法，在6-311G(d)基组水平上对该化合物基态分子构型进行了几何结构全优化，得到了其最稳定构型、总能量及HOMO与LUMO能级差。研究结果说明：分子具有较强的芳香性和较大的共轭体系。振动频率分析说明，标题分子优化后的结构稳定。将优化后的基态结构应用含时密度泛函理论(TD-DFT)，在B3LYP/6-311G水平上计算并研究了此化合物的吸收光谱。用单激发组态相互作用(single-excitation configuration interaction, CIS)法优化了标题分子的激发态构型，并在此基础上用TD-DFT//B3LYP/6-311G方法计算了这种化合物的发射光谱。结果表明，理论计算的光谱数据与实验结果较吻合。

Theoretical Study on Geometrical Structure and Spectrum of 4-(2-Nitrobenzylideneamino)Phenyl Ethanone Schiff Base

The UV absorption spectra, fluorescence emission spectra and fluorescence quantum yield of the title Schiff base were studied by experiment. The results showed that this compound displayed superior fluorescence properties. Geometrical optimization of the title compound was carried out by employing density functional theory (DFT) method at the B3LYP/6-311G(d) level. The calculation results indicated that the title compound has comparatively stronger aromaticity and larger conjugate system. For the optimal configuration, there is no imaginary frequency after vibrational analysis, which indicates that the structure is stable. Based on the optimized structure for the ground state time-dependent density functional theory (TD-DFT) calculations were carried out at the B3LYP/6-311G level to predict the absorption spectra. The single-excitation configuration interaction (CIS) method was used to optimize the structure of the first excited state, and then TD-DFT calculations were carried out to predict the emission spectra. The results indicated that the wavelengths of the absorption and emission spectra are consistent with the experimental data.