Peroxide Activation Catalyzed by a Complex between Copper Ions and a Bioinspired Polyampholyte: Mechanism and Applications

JUAN MANUEL LÁZARO MARTÍNEZ; ENRIQUE RODRÍGUEZ CASTELLÓN; LISANDRO DENADAY; GRACIELA YOLANDA BULDAIN; IRENE REZZANO; VIVIANA CAMPO DALL´ORTO

Estrasburgo

Conferencia; Hybrid Materials 2011, Second International Conference on Multifunctional, Hybrid and Nanomaterial; 2011

Elsevier

A bioinspired polyampholyte one-pot synthesized from methacrylic acid, imidazole and ethyleneglycol diglycidyl combines functionalities found in coordination sites of metalloproteins such as ceruloplasmin, transferrin, carbonic anhidrase and superoxide dismutase. This material bound Cu(II) with a maximum loading capacity of 57 mg g-1. FTIR spectrum of the complex exhibited a new band at 600 cm-1 assigned to N-Cu, and an important decrease in COO- asymmetric stretching band at 1570 cm-1, confirming that imidazole and carboxylate residues are both involved in coordination. The complex between Cu(II) and the bioinspired polyampholyte was used as a heterogeneous catalyst for hydrogen peroxide activation. The proposed mechanism involves Cu(I) as probable intermediate, giving dioxygen, hydroxyl radicals and water as products. The formation of free radicals that diffused into the solution was confirmed by spin trapping experiments. The profile concentration of the DMPO/•OH adduct presented a maximum after 40 minutes of reaction. The catalyst presented several remarkable changes in the XPS spectrum after treatment with H2O2. The Cu 2p3/2 appeared at 933.4 eV in absence of shake-up satellite peaks, which is consistent with Cu(I). The N 1s signals from imidazole residues and the O 1s signals assigned to the C=O, -COO-, -OH and C-O-C groups were shifted towards higher binding energies in the Cu(I) complex. This indicates that all the groups are involved in the charge transfer from the ligands to Cu(I) in coordinated bonds. Cu(II)-polyampholyte was tested as a heterogeneous catalyst for H2O2 activation and the degradation of methyl orange (an azo-dye), 2,4-dichlorophenol and 2,4,5-trichlorophenol. After the addition of the complex to a solution of the dye, the release of gas was followed by color removal by degradation combined with adsorption to the polymer. For the chlorinated phenols, the rate of degradation was enhanced and the extension of the reaction was also improved.