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对2-(4-取代苯基)乙烯基吡啶系列用密度泛函法(DFT),在B3LYP/6-31+G**冰平上全优化几何构型,探讨苯环对位上不同取代基对分子电荷的转移、前线轨道能量等性质的影响规律。结果,电子由苯环向乙烯链移动,并通过乙烯链再向吡啶环移动;前线轨道能量随着取代基吸电子能力的增加而降低,随着供电子能力的增强而升高。在此基础上采用含时密度泛函(TD-DFT)计算分子第一激发态的电子跃迁能,得到最大吸收波长λ_(max)。计算结果,6个化合物的最强跃迁都由于基态到单重激发态分子的HOMO→LUMO跃迁,由轨道对称性可知为π→π*跃迁。引入上述5种取代基,均导致最大吸收波长红移。
For the 2- (4-substituted phenyl) vinylpyridine series, the geometries were fully optimized by density functional theory (DFT) at B3LYP / 6-31 + G ** ice level, The base of the charge transfer, frontier orbital energy and other properties of the law. As a result, the electrons move from the benzene ring to the ethylene chain and then to the pyridine ring through the ethylene chain. The energy of the frontier orbital decreases as the electron-withdrawing ability of the substituent increases and increases with the electron-donating ability. On this basis, the electronic transition energy of the first excited state of the molecule is calculated by using time-dependent density functional theory (TD-DFT), and the maximum absorption wavelength λ max is obtained. The calculated results show that the strongest transitions of all six compounds are due to the HOMO → LUMO transition from the ground state to the singlet excited state and the π → π * transition from the orbital symmetry. The introduction of the above five kinds of substituents, have led to the maximum absorption wavelength redshift.