Polarity-Dependent Isomerization of an Unsymmetrical Overcrowded Ethylene Promoted by Zwitterionic Contribution in the Twisted Isomer
作者:Yasukazu Hirao、Nobuhiro Nagamachi、Katsuma Hosoi、Takashi Kubo
DOI:10.1002/asia.201701805
日期:2018.3.2
reaction between the folded and twisted isomers. With increasing the polarity of the solvent, 2 showed an isomerization reaction from the folded form to the twisted form. The stabilization of the twisted isomer in polar solvents can be interpreted as proof of its relatively large zwitterionic character. The DMF solution of 2 displayed paramagnetically‐broadened NMR signals from the thermally populated triplet
联蒽酮的扭曲形式被称为亚稳态,是由折叠形式的光诱导或热诱导异构化提供的,因此阻碍了对其电子结构的隔离和详细分析。在这项研究中,合成了一个不对称的联蒽酮(2),它由吸电子的蒽酮和给电子的cri啶组成,并显示出折叠和扭曲异构体之间的溶剂极性依赖性异构化反应。随着溶剂极性的增加,2显示出从折叠形式到扭曲形式的异构化反应。扭曲异构体在极性溶剂中的稳定性可以解释为其相对较大的两性离子特性的证明。DMF解决方案2 从扭曲异构体的弱烯键双键旋转产生的热填充三重态显示顺磁增强的NMR信号。