氰乙基对几种芳胺结构和光谱的影响

采用量子化学中密度泛函理论(DFT)的B3LYP方法分别用6-31G*和6-311+G*基组对苯胺、对氯苯胺和对甲苯胺及其氰乙基衍生物的几何构型进行全优化, 探讨了氨基上氰乙基的引入对分子电荷转移、前线轨道能量和电子光谱等性质的影响规律. 在此基础上采用含时密度泛函方法(TD-DFT)计算了分子第一激发态的电子跃迁能, 得到最大吸收波长λmax. 计算结果表明, 氨基上氰乙基的引入, 对前线分子轨道组成影响虽然小, 但使得最大吸收波长红移, 与实验值λmax有较好的一致性, 发现该类物质主要吸收光谱源于分子内的π→π*的电子跃迁.

Impact of Cyanoethy Groups on Structure and Spectroscopy of a Few Aromatic Amines

The impact of introducing cyanoethy groups in aromatic amines on structure, charge transfer, frontier orbital energy and composition, as well as electronic absorption spectra was investigated in this work. Theoretical studies of aniline, p-chloroaniline, p-toluidine, and cyanoethy derivatives were carried out at density functional theory (DFT) B3LYP/6-31G* and B3LYP/6-311+G* levels to obtain optimized geometrical structures. Time-dependent density functional theory was applied to calculate the first excited state electronic transition energy and maximum absorption wavelength λmax. Our results indicate that the introduction of a cyanoethy group has limited effect on the composition of frontier orbitals. The main absorption spectrum originates from the featured π→π* electronic transition. The predicted spectra agree well with the available experimental findings.