investigate the reterdation effects of ortho substituents, the activation parameters were determined; the results suggest that the steric hindrance among the ortho substituents and the two nitrogen lone pairs of the azo group becomes far more severe in an inversional transition-state than in the ground cis-state, which leads to the remarkable slow cis-to-trans isomerization. On the basis of the kinetic data
为了在功能分子设计中利用
苯基偶
氮萘的可逆光致变色体系,研究了各种取代
苯基偶
氮萘的光致变色行为。在偶
氮基的邻位上引入取代基延缓了热顺式到反式异构化的速率。延迟效应很大程度上取决于邻位取代基的数量和位置。为了研究邻位取代基的阻滞效应,确定了活化参数;结果表明,在倒转过渡态中,邻位取代基和偶
氮基团的两个
氮孤对之间的空间位阻比在基顺态中严重得多,这导致显着缓慢的顺式到反式异构化。