Novel macrocyclic heterodinuclear catalase-like model complex CuMnL and CuZnL (L = BDBPH): synthesis, stability and catalytic properties

The macrocyclic ligand BDBPH was used as a dinuclear chelating ligand to synthesize the heterodinuclear complexes Cu(II)M(II)BDBPH [M(II) = Zn(II) and Mn(IQ. Titration experiments show that different heteronuclear species CuM(II)(OH)n (n = 1-2) co-exist in water solution at a pH range of 7-12. Catalytic experiments reveal that these complex systems can dismutate H2O2 to O-2 effectively in basic water solution. Mechanism studies by means of electronic spectra and ESR show that the active center of these catalysts is a dimer structure. The substrate H2O2 molecules are dismuted through a homo-cleaving pathway. The catalytic activity of Cu(II) can be greatly enhanced by the other phenol bridged metal ions in the same complex molecule. A novel inter- and intra-molecular cooperation mechanism was proposed to illustrate the efficient catalytic process. (C) 2001 Elsevier Science B.V. All rights reserved.