Biomimetic Cu,Zn and Cu2 complexes inserted in Mesoporous Silica as Catalysts for Superoxide Dismutation

MATÍAS PATRIARCA; VERÓNICA DAIER; GERARDO CAMÍ; NORA PELLEGRI; ERIC RIVIÈRE ; CHRISTELLE HUREAU; SANDRA SIGNORELLA

MICROPOROUS AND MESOPOROUS MATERIALS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2018 vol. 279 p. 133 - 141

1387-1811

Three CuZn-superoxide dismutase (SOD) functional mimics, [CuZn(dien)2(μ-Im)](ClO4)3 (1), [Cu2(dien)2(μ-Im)](ClO4)3 (2) (Im = imidazole, dien =diethylenetriamine), and [CuZn(salpn)Cl2] (3) (H2salpn = 1,3-bis(salicylideneamino)propane), were successfully inserted into the nanochannels ofSBA-15 type mesoporous silica with retention of the silica mesostructure. X-rayabsorption spectroscopic studies indicate that the encapsulated complexes keepunchanged the first-shell environment of Cu(II) and Zn(II) ions. Magneticmeasurements suggest that the nanochannels constrain the geometry of the -imidazolate-Cu(II)2 core modifying the relative orientation of the two coppercoordination planes. Confinement imposed by the silica nanochannels uponencapsulation of complexes 1 and 2 leads to stable hybrid materials at physiologicalpH with enhanced SOD activity relative to the free complexes. Unlike the imidazolatobridgedcompounds, insertion of 3 in mesoporous silica leads to a less stable hybridmaterial exhibiting partial release into the aqueous solution and O2 dismutation rateslower than the free complex. The covalent binding of a mononuclear Cu(dien)Im+moiety to the mesoporous silica showed lower SOD activity than encapsulatedimidazolato-bridged CuZn and Cu2 complexes, highlighting the key role of