EFFECT OF ANCHORING DINUCLEAR Mn(III)-SCHIFF BASE COMPLEXES INTO MESOPOROUS SILICA IN THEIR CATALASE ACTIVITY

WILLIAMS, ALEJANDRO; PALOPOLI, CLAUDIA; GÓMEZ, GUILLERMO; SIGNORELLA, SANDRA; RICHEZZI, MICAELA; CAMI, GERARDO

Iguazú

Simposio; 6to Simposio Latinoamericano de Química de Coordinación; 2017

DiMn(III) complexes of 1,5-bis(X-salicylidenamino)pentan-3-ol (X= H, 5-OMe,5-Me, 3-Me) (1-4) and 1,5-bis(2-hydroxybenzophenylideneamino)pentan-3-ol(5) are good catalase mimics in non protic solvents, but inactivate after a fewturnover numbers in protic solvents as a consequence of metal dissociation.The insertion of Mn catalase mimics in mesoporous silica confershydrophobicity and confinement and has proven to protect the catalyst fromundesired degradation [1].SBA-15 is well studied and highly stable mesoporous silica with applicationsin drug delivery, enzyme immobilization and catalysis. Solutions ofcomplexes 1-5 were added to SBA-15 suspended in methanol and stirredovernight at room temperature. The resulting suspensions were filtered, andthe powders were washed several times with methanol until the solutionswere clear, and dried at 80 °C. The solids were analyzed by TG-DSC andFTIR-ATR. The amount of adsorbed complex was estimated from thedifference between the initial and final concentrations of the complexes insolution. The ability of complex@SiO2 to catalyze H2O2 decomposition wastested in methanol, by measuring evolved oxygen volumetrically. Thestability of the adsorbed catalysts was controlled by UV-vis spectroscopy.1(4,5)@SiO2 showed higher turnover numbers, but 2(3)@SiO2 were poorerthan the free complexes, with lower turnover frequencies.