Enhancing the photocatalytic performance of Co(II) and Cu(II) phthalocyanine by containing 1,3,4 thiadiazole groups in 4-nitrophenol oxidation reaction

Designing an eco-friendly and low cost catalyst with high efficiency and selectivity to rapidly clean up phenolic compounds is urgently to be a priority. In this work, we have synthesized and characterized 1,3,4-thiadizaole substituted copper and cobalt phthalocyanine 4 and 5 as catalysts on 4-nitrophenol photoxidation. To determine the optimum conditions of 4-NP photoxidation, we have investigated catalyst amount and solvent effect. 2000/1 was detected as suitable substrate/catalyst ratio to give the highest product conversion (90 % for complex 4 and 95 % for complex 5). Dichloromethane, tetrahydofuran, hexane and toluene were tested as different solvent for 4-NP photoxidation and dichloromethane was found the best solvent for both catalysts. The catalytic turnover frequencies of 4 and 5 for photoxidation of 4-NP were determined to be 900 h-1 and 950 h-1, respectively, which were better values than those of the catalysts in our works. Complex 5 maintained conversion (from 95 % to 32 %) after four continuous cycles and the entire catalytic and recovery process could be achieved by separation of two phase reaction mixture.