【摘要】 采用量化计算和分子模拟方法,设计、合成了9种不同结构的氯化金属卟啉铁催化剂,并对其前线轨道能量进行了计算,将计算结果与其催化氧气液相氧化对硝基甲苯制取对硝基苯甲酸反应的活性数据相结合,研究了不同结构的五配位金属卟啉铁催化剂的微观结构(EHOMO和ΔEL-H)与催化活性(产物收率)之间的关系,建立了相应的定量构效关系(QSAR)式.经统计检验量检验,发现五配位金属铁卟啉的EHOMO对催化活性的影响大于ΔEL-H对催化活性的影响.根据拟合的定量关系,对环外取代基为甲基的2种五配位金属铁卟啉催化剂的活性进行了预测,并经实验验证,证明所预测的活性与实测的活性相符.更多还原

【Abstract】 Nine chloro-iron tetraphenylporphyrin (RTPPFeCl) compounds were designed and synthesized, and their catalytic activities were characterized by using dioxygen liquid-phase oxidation of p-nitrotoluene (PNT) to p-nitrobenzoic acid (PNBA) as model reaction, and their molecular frontier orbital energies E_ HOMO , E_ LUMO , ΔE_ L-H etc were calculated by using the PM3 semi-empirical molecular orbital method.The QSAR(quantitative relationship between structure and catalytic activity)of chloro-iron tetraphenylporphyrin (RTPPFeCl) was investigated by combining activity (yield of PNBA) with E_ HOMO and ΔE_ L-H of 9 catalysts.It was found that there was excellent linear correlation between catalytic activity and frontier orbital energy.Through linear regression the following equations were obtained: that is, for T(o-R)PPFeCl, Y=71.766-8.166E_ HOMO -10.701ΔE_ L-H , and correlation coefficient R=0.964.For T(p-R)PPFeCl: Y=80.031-9.297E_ HOMO -14.288ΔE_ L-H , and correlation coefficient R=0.998.It was also concluded that the effect of E_ HOMO on catalytic activity was larger than that of ΔE_ L-H for 5-coordinate of iron porphyrins.E_ HOMO was the main structure parameter influencing catalytic activities of 5-coordinate of iron-porphyrin compounds.Moreover the catalytic activities of two iron-porphyrin compounds with substituted methyl group were predicted according to this relationship.The results showed that the catalytic activity of metalloporphyrin was consistent with that predicted.The results made it possible to use the model of structure-activity relationship to predict unknown catalysts.Finally, the same correlation between the catalytic activities and electronic structure parameters of the Co, Mn and Fe metal porphyrins were obtained according to the authors’ research work published in three papers.These results will help not only to enrich biomimetic catalytic theory, but also to design excellent biomimetic catalysts from molecular levels.更多还原