Synthesis and photocatalytic properties of iron(II)tetramethyl- tetra(1,4-dithiin)porphyrazine

The titled complex has been synthesized according to the template method from the prepared intermediate of 2,3-dicyano-5-methyl-1,4-dithiin in the presence of iron(II)sulfate heptahydrate and characterized by UV–vis, FT-IR , 1H NMR, XPS and elemental analysis. The complex was supported on an Amberlite CG-400 resin to form a biomimetic catalyst, the ability of which for activating molecular oxygen was estimated from the degradation of Rhodamine B (RhB) under visible light irradiation in an aerated suspension. About 78% of the RhB was degraded in 27 h with a rate constant of 1.84 × 10−10 mol L−1 s−1. Aggregation between the dimer and monomer for the titled complex in DMSO or in DMF solution was observed from the concentration dependence in the UV–vis spectra. The effect of the aggregation was also demonstrated by the diffuse reflectance spectral measurement for the catalyst supported on the resin in saturated and supersaturated adsorption conditions. The monomer of catalyst has a higher capability to activate molecular oxygen for the degradation of organic pollutants than that of an aggregation form.