Cu2+-phthalocyanine and Co2+-perfluorophthalocyanine incorporated inside Y faujasite and mesoporous MCM-41 as heterogeneous catalysts for the oxidation of cyclohexane Original Research Article

A series of Cu2+-phthalocyanine and Co2+-perfluorophthalocyanine has been prepared inside the pores of MCM-41 (MPcMCM-41) by synthesis from o-dicyanobenzene. The complexes were characterized by comparison of the UV–Vis diffuse reflectance and IR spectra with that of the same unsupported complexes. Transition metal ion exchange levels higher than 40% were found necessary for the success of the synthesis. o-Cyanobenzoic acid and phthalic anhydride were isolated as byproducts. Differential scanning calorimetry indicates that the complexes are more stabilized inside MCM-41 than within the supercages of Y faujasite. This has been interpreted as a reflection of the different conformations (planar for MCM-41 and distorted for Y faujasite) depending on the pore size of the host. The catalytic performance of novel MPcMCM-41 for cyclohexane oxidation was compared with that of the same unsupported complexes or when encaged within Y faujasite. tert-Butyl hydroperoxide was found as a more convenient oxidizing reagent than hydrogen peroxide. No leaching of the MPc or uncomplexed metal ions was observed. It was found that CoF16PcMCM-41 was more active and selective than CoF16PcY or unsupported CoF16Pc. However, in the case of the CuPc complex, the highest activity and selectivity was achieved using CuPcY. Our work shows the influence that the void dimensions of the porous host can play in the performance of metallophthalocyanines as oxidation catalysts.