Application of metal complexes as biomimetic catalysts on glycerol oxidation

Two biomimetic complexes were evaluated as catalysts in the H2O2 mediated oxidation of glycerol, namely a peroxidase mimetic Fe(III) protoporphyrin complex (hematin) and the superoxide-dismutase mimetic complex of Mn(III) with 1,3-bis(5-sulphonatesalycilidenamino) propane (MnL−). Catalysis was targeted to glyceraldehyde since antimicrobial power was proved for it. Glyceraldehyde evolved at a higher rate than the uncatalyzed reaction only with hematin acid treated solutions and kinetics were typical of a radical mechanism. Nonetheless, glycerol conversions were low. H2O2 bleached hematin and the immobilization on a porous matrix could not prevent this. Meanwhile, the catalatic activity of hematin was high but its peroxidatic activity was inhibited at pH > 8. Thus, the coordination of hematin compound I to H2O2 over glycerol may be the preferred route with the accumulation of peroxy radicals, able to degrade the porphyrinic ring -with probable iron releasing- but also contributing to glycerol oxidation. On the other hand, a prompt decay with time of the catalatic and peroxidatic activities of MnL− was observed, which was improved by the addition of dimethylsulfoxide (DMSO), dimethylformamide (DMF) or acetone to the basic buffer system. Finally, EPR spectroscopy of MnL− supported the hypothesis of the formation of an inactive bis-oxo-bridged Mn(IV)Mn(IV) dimer upon addition of H2O2.

Bibliographic Details

Main Authors:	Parodi, Adrián Rodrigo, Merlo, Carolina, Córdoba, Agostina, Palopoli, Claudia, Ferreyra, Joaquín, Signorella, Sandra, Ferreira, María Luján, Magario, Ivana
Format:	article biblioteca
Language:	eng
Published:	2020
Subjects:	Oxidación, Reacciones químicas, Catalizador, Glicerol,
Online Access:	http://hdl.handle.net/11086/29028 https://doi.org/10.1016/j.mcat.2018.11.007 https://www.sciencedirect.com/journal/molecular-catalysis
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