title: Synthesis, characterization and activity of imidazolate-bridged and Schiff-base dinuclear complexes as models of Cu,Zn-SOD. A comparative study.
abstract: Two imidazolate-bridged diCuIIand CuIIZnIIcomplexes, [CuZn(dien)2(μ-Im)](ClO4)3·MeOH (1) and [Cu2(dien)2(μ-Im)](ClO4)3(2) (Im = imidazole, dien=diethylenetriamine), and two complexes formed with Schiff base ligands, [CuZn(salpn)Cl2] (3) and [Cu2(salbutO)ClO4] (4) (H2salpn=1,3-bis(salicylidenamino)propane, H3salbutO=1,4-bis(salicylidenamino)butan-2-ol) have been prepared and characterized. The reaction of [Cu(dien)(ImH)](ClO4)2with [Zn(dien)(H2O)](ClO4)2at pH≥11 yields complex 1; at lower pH, the Cu3Zn tetranuclear complex [{(dien)Cu(μ-Im)}3Zn(OH2)(ClO4)2](ClO4)3(1a) forms as the main reaction product. X-ray diffraction of 1a reveals that the complex contains a metal centered windmill-shaped cation having three blades with a central Zn ion and three peripheral capping Cu(dien) moieties bound to the central Zn ion through three imidazolate bridges. The four complexes are able to disproportionate O2-in aqueous medium at pH7.8, with relative rates 4>1>2≫3. [Cu2(salbutO)]+(4) is the most easily reducible of the four complexes and exhibits the highest activity among the SOD models reported so far; a fact related to the ligand flexibility to accommodate the copper ion in both CuIand CuIIoxidation states and the lability of the fourth coordination position of copper facilitating stereochemical rearrangements.
authors.affiliation: IQUIR (Instituto de Química Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina.
authors.forename: Verónica A
authors.initials: VA
authors.lastname: Daier
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay, 91405 Orsay Cedex, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Rivière
authors.affiliation: Institut de Chimie de Toulouse, FR 2599, 118 Route de Narbonne, F-31062 Toulouse, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Mallet-Ladeira
authors.affiliation: IQUIR (Instituto de Química Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina.
authors.forename: Diego M
authors.initials: DM
authors.lastname: Moreno
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, F-31077 Toulouse, France; UPS, INPT, LCC, Université de Toulouse, 205 route de Narbonne, F-31077 Toulouse, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Hureau
authors.affiliation: IQUIR (Instituto de Química Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina. Electronic address: signorella@iquir-conicet.gov.ar.
authors.forename: Sandra R
authors.initials: SR
authors.lastname: Signorella
mesh_terms: D003300:Copper / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D012545:Schiff Bases / Q000737:chemistry; D013482:Superoxide Dismutase / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry*
chemical_list: D007093:Imidazoles; D012545:Schiff Bases; D013481:Superoxides; D003300:Copper; D013482:Superoxide Dismutase
keywords: Cu/Zn complexes; SOD activity; Stability; Structure