Ground-State Conformational Equilibrium and Photochemical Behavior of Syn and Anti <i>N</i>,<i>N</i><i>‘</i>-Dimethyl-<i>N</i>,<i>N</i><i>‘</i>-di-1-naphthylurea Protophanes
作者:Todd L. Kurth、Frederick D. Lewis
DOI:10.1021/ja034311w
日期:2003.11.1
The structure, spectroscopy, and photochemistry of N,N'-dimethyl-N,N'-di-1-naphthylurea have been investigated and compared to the properties of the corresponding secondary diarylurea N,N'-di-1-naphthylurea and the tertiary mono arylurea N,N,N'-trimethyl-N'-1-naphthylurea. The crystal structures and solution NMR spectra of the tertiary and secondary dinaphthylureas establish that they adopt folded
研究了 N,N'-二甲基-N,N'-di-1-naphthylurea 的结构、光谱和光化学,并与相应的仲二芳基脲 N,N'-di-1-naphthylurea 和叔单芳基脲 N,N,N'-三甲基-N'-1-萘脲。叔二萘脲的晶体结构和溶液 NMR 谱表明它们在固态和溶液中分别采用折叠 (E,E) 和扩展 (Z,Z) 结构。在溶液中,叔 E,E-二萘脲作为顺式和反式构象的混合物存在,被约 14 kcal/mol,由变温 (1) H NMR 光谱测定。对基态势能面的计算探索表明,顺式和反式构象异构体相互转化的最低能量途径需要同时围绕氮-萘和氮-羰基单键旋转。由于萘环之间的激子相互作用,叔联萘脲表现出蓝移吸收和红移发射。二级二萘脲和单萘脲具有典型的类萘单体吸收和荧光光谱。双指数荧光衰减分配给三级联萘脲的两个构象异构体。荧光衰减时间的非线性拟合为两个构象异构体的单线态衰减提供了激活参数。衰变过程归