A novel magnetically recoverable thioporphyrazine catalyst(CoPz(S-Bu)_8/SiO2@Fe3O4) was prepared by immobilization of the cobalt octkis(butylthio) porphyrazine complex(CoPz(S-Bu)_8) on silica-coated magnetic nanospheres(SiO_2@Fe_3O_4). The composite CoPz(S-Bu)_8/SiO_2@Fe_3O_4appeared to be an active catalyst in the oxidation of benzyl alcohol in aqueous solution using hydrogen peroxide(H_2O_2) as oxidant under Xe-lamp irradiation,with 36.4% conversion of benzyl alcohol, about 99% selectivity for benzoic acid and turnover number(TON) of 61.7 at ambient temperature. The biomimetic catalyst CoPz(S-Bu)_8was supported on the magnetic carrier SiO_2@Fe_3O_4 so as to suspend it in aqueous solution to react with substrates, utilizing its lipophilicity. Meanwhile the CoPz(S-Bu)_8can use its unique advantages to control the selectivity of photocatalytic oxidation without the substrate being subjected to deep oxidation. The influence of various reaction parameters on the conversion rate of benzyl alcohol and selectivity of benzoic acid was investigated in detail. Moreover, photocatalytic oxidation of substituted benzyl alcohols was obtained with high conversion and excellent selectivity, specifically conversion close to 70%, selectivity close to 100% and TON of 113.6 for para-position electron-donating groups. The selectivity and eco-friendliness of the biomimetic photocatalyst give it great potential for practical applications.
Huan LiLan CaoChangjun YangZhehui ZhangBingguang ZhangKejian Deng
