Structures and Excited States of Extended and Folded Mono-, Di-, and Tri-<i>N-</i>Arylbenzamides
作者:Frederick D. Lewis、Timothy M. Long、Charlotte L. Stern、Weizhong Liu
DOI:10.1021/jp0264937
日期:2003.5.1
The relationship between molecular structure and electronic properties of 18 N-arylbenzamides has been investigated. The secondary amides adopt extended trans-amide conformations, whereas the tertiary amides adopt folded cis-amide conformations in which the N-aryl group is approximately perpendicular to the benzoyl group. The N-aryl groups of the tertiary di- and triamides occupy the same face of the
研究了 18 N-芳基苯甲酰胺的分子结构与电子性质之间的关系。仲酰胺采用扩展的反式酰胺构象,而叔酰胺采用折叠的顺式酰胺构象,其中N-芳基大致垂直于苯甲酰基。叔二酰胺和三酰胺的 N-芳基占据苯甲酰基的同一面并显示出边对面的芳基-芳基相互作用。随着 N-芳基数量的增加,仲酰胺的长波长吸收最大值红移,而叔酰胺显示蓝移。ZINDO 计算有助于分配吸收和发光光谱。在所有情况下,最低能量单重态被分配给禁止的 n,B*(羰基孤对到苯甲酰基)跃迁。二级和三级酰胺的无结构荧光分别归属于平面和扭曲的 n,B* 单峰。允许的吸收带分配给 A,B*(芳烃到苯甲酰基)或 A,A*(芳烃到芳烃)跃迁,它们位于单个芳烃上,结构化磷光分配给 A,A*三重态。