关键词: 金属卟啉, 催化剂, 量化计算, 催化活性

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.

Key words: 金属卟啉, 催化剂, 量化计算, 催化活性