四吡啶基卟啉质子化结构变化研究Ⅱ.m-甲基吡啶基的取代基效应

摘要

Porphyrin derivatives have sensitive selectivity to molecular intercalation and aggregation in DNA helix. On the basis of the study of tetrapyridylporphine, in order to investigate the effects of meso-(p-methylpyridyl) to the structure of N - protonated porphyrin, the geometries of meso-tetrakis (p-methylpyridyl)porphyrin (TmPyPH24+ )and its diacid(TmPyPH46+ ) were calculated by using AM1 MO method under certain symmetry restriction. The results show that in the protonation process, because of the effect of meso-(p-methylpyridyl), the changes of the structure and bond charge population are obvious; the frontier molecular orbitals have opposite change trend with the case of meso-yridyl, the rapid exchanges of inner hydrogens of the protonated diacid with solvent protons become more difficult.%卟啉衍生物对嵌入并堆积在DNA螺旋中具有高选择性.为考察m-甲基吡啶取代基对质子化卟啉结构的影响，在m-四吡啶基卟啉研究的基础上，用半经验的AM1 MO方法，并进行合理的对称性限制，计算了m-四甲基吡啶卟啉(TmPyPH24+)及其质子化二酸(TmPyPH46+)的几种可能的构型.结果表明，由于m-甲基吡啶的影响，在质子化过程中结构和键电荷布居有明显变化；前沿分子轨道具有与四吡啶基情形相反的变化趋势，质子化二酸与溶液质子的快速交换作用也变得更困难了.