水杨醛缩对乙酰基苯胺希夫碱的合成及其荧光性质的理论研究

Synthesis and Theoretical Study on Fluorescence Property of 4-(2-Hydroxybenzylideneamino)Phenyl Ethanone Schiff Base

以水杨醛和对乙酰基苯胺为原料,首次采用绿色环保的室温固相反应方法制备了水杨醛缩对乙酰基苯胺希夫碱,用元素分析和核磁共振氢谱对产物进行了表征。测定了产物的紫外光谱、荧光光谱和相对荧光量子效率,发现该化合物具有较强的荧光性质。利用密度泛函理论(density functional theory,DFT)方法,在B3LYP/6-311G基组水平上优化了该化合物的基态分子构型。采用相同的方法和基组计算了标题化合物的振动频率,频率数据中没有虚频,即该优化构型是稳定的。分析理论计算结果发现:标题分子具有较强的芳香性和较大共轭体系。在基态优化结构的基础上应用含时密度泛函理论(TD-DFT),在B3LYP/6-31G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(CIS)方法优化了标题分子的激发态构型,并在此基础上用TD-DFT//B3LYP/6-31G方法计算了这种化合物的荧光发射光谱。将理论计算的光谱性质与实验的光谱数据相比较发现二者吻合较好。分析探讨了化合物分子的结构与其荧光性质之间的关系,为进一步寻找具有荧光性质的化合物提供了理论指导。

Using salicylaldehyde and 4-aminophenyl ethanone as raw material, a Schiff base derivative 4-（2-hydroxybenzylidene- amino）phenyl ethanone was synthesized by the solid phase reaction method at room temperature. The structure of the product was characterized by elemental analysis and a HNMR. The UV spectra, fluorescence emission spectra and fluorescence quantum yield of the title Schiff base derivative were investigated. The results showed that this Schiff base displayed superior fluorescence property. The ground state configuration of the title Schiff base was optimized by density functional theory （DFT） method at the B3LYP/6-311G level. After vibrational analysis, there is no imaginary frequency, which indicates that the structure is stable. Then the ground state configuration was optimized to the excited state configuration by the method of single excited interactions CIS. Based on the optimized structure for the ground state and excited state time-dependent density functional theory （TD-DFT） calculations were carried out at the B3LYP/6-31G level to predict the absorption spectra and the fluorescence spectra. The re- sults show that the computed spectra were comparable with the spectra from the experiments. The relationship between the mo- lecular structure and the fluorescence property of 4-（2-hydroxybenzylideneamino）phenyl ethanone was also discussed. The re- suits obtained may provide some theoretical guidance for the design of new fluorescence compounds.