密度泛函数理论研究取代基对X-PhPhCH=NPh-Y构型的影响

DFT study of the substituent cross-interaction effects on the conformation of X-PhPhCH=NPh-Y

采用密度泛函方法在B3LYP/6-31G*水平上优化了49个模型化合物X-Ph Ph CH=NPh-Y的几何构型,获得了化合物苯胺环与C=N的二面角τ2.为了验证计算结果的可靠性,合成并培养了Ph Ph CH=NPh-OMe化合物的单晶.研究表明,二面角τ2随着取代基X和Y的变化而显著地变化,τ2变化范围为142.42°~156.90°.计算结果和实验数据基本吻合,表明该计算方法具有较好的可靠性;在此基础上,研究了模型化合物中取代基对二面角τ2的影响,同时还构建了一个能表达取代基和分子构型关系的定量模型.该研究为探讨芳基希夫碱分子中取代基对分子构型的影响提供了一种切实可行的方法.

The conformations of N-benzylideneanilines X-PhPhCH = NPh-Y were studied by B3LYP （DFT） hybrid method in combination with the 6-31G ＊ split valence basis set. It was observed that the twist angle of the benzylidene ring or aniline ring with respect to the rest of the molecule （τ1 or τ2） estimated by the DFT method are highly reliable, and τ2 can be systematically regulated through X and Y substitution. The substituent effects on τ2 obtained from DFT calculations were investigated. It is demonstrated that substituent cross-interaction has a certain influence on τ2, and a quantitative model was proposed to express such an effect. The findings of the present study illustrate a practical method for expressing the relationship between substituents and molecular conformation of the X-PhPhCH = NPh-Y compounds.