作者:A.H.A. Tinnemans、W.H. Laarhoven
DOI:10.1016/0040-4020(79)80041-1
日期:1979.1
Line-shape analysis of temperature dependent NMR spectra of several substituted 4,5-diphenyl-triphenylenes has been performed to determine the free energy of activation for rotation (ΔGrot*) of the phenyl groups. The rotational barrier (ΔGrot*) depends on the presence and position of substituents on the phenyl groups; it is the largest in compounds with ortho-substituents. The independent determined
已被执行的几个取代的4,5-二苯基苯并菲依赖于温度的NMR谱的线形分析来确定的自由能激活旋转(ΔG腐*)的苯基基团。旋转阻挡(ΔG腐*)取决于在苯基基团的取代基的存在和位置; 它是具有邻位取代基的化合物中最大的。独立确定外消旋(ΔG的活化自由能外消旋*)约等于ΔG腐*在4-苯基-5-(3,5-二甲基苯基)三亚苯,但是在4,5-双- (3,5-二甲基苯基)菲ΔG RAC *比ΔG大得多腐*。可以得出结论,外消旋不是通过苯基保持平行的过程发生的,而是通过分子移动(其中苯基彼此像齿轮一样旋转)发生的。