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 EHOMO

ELUMO

ΔEL-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 EHOMO and ΔEL-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=71.766-8.166EHOMO-10.701ΔEL-H

and correlation coefficient R=0.964.For T(p-R)PPFeCl: Y=80.031-9.297EHOMO-14.288ΔEL-H

and correlation coefficient R=0.998.It was also concluded that the effect of EHOMO on catalytic activity was larger than that of ΔEL-H for 5-coordinate of iron porphyrins.EHOMO 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.