Substituent Cross-Interaction Effects on the Electronic Character of the CN Bridging Group in Substituted Benzylidene Anilines − Models for Molecular Cores of Mesogenic Compounds. A <sup>13</sup>C NMR Study and Comparison with Theoretical Results
作者:Helmi Neuvonen、Kari Neuvonen、Ferenc Fülöp
DOI:10.1021/jo0600508
日期:2006.4.1
could be verified. The electronic effects of the neighboring aromatic ring substituents systematically modify the sensitivity of the CN group to the electronic effects of the benzylidene or aniline ring substituents. Electron-withdrawing substituents on the aniline ring decrease the sensitivity of δC(CN) to the substitution on the benzylidine ring, while electron-donating substituents have the opposite
在CDCl 3中,对一系列介晶分子模型化合物(即C 13)测量了13 C NMR化学位移δC (C N)。取代的亚苄基苯胺p -X C 6 H 4 CH NC 6 H 4 p -Y(X = NO 2,CN,CF 3,F,Cl,H,Me,MeO或NMe 2; Y = NO 2,CN ,F,Cl,H,Me,MeO或NMe 2)。δ的取代基依赖性Ç(CN)被用作研究电子取代基对偶氮甲碱单元的作用的工具。亚苄基取代基X有δ的反向效应Ç(C N):吸电子原因屏蔽的取代基,而给电子性的人的行为相反,感应效果清楚地在共振效应为主。相反,苯胺取代基Y发挥正常作用:吸电子取代基引起屏蔽,而供电子取代基引起C N碳屏蔽,感应效应和共振效应的强度非常相似。此外,可以验证X和Y之间是否存在特定的交叉相互作用。相邻芳环取代基的电子效应可系统地改变C的灵敏度N基团对亚苄基或苯胺环取代基的电子作用。吸电子苯胺环上的取代基降低δ的灵敏度Ç(C