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(II)]. 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 O2 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.