Research Projects

Catechol oxidase is a type 3 copper enzyme that converts o-diphenols to o-quinones. Its active site has a dicopper core, reduced Cu(I) ions coordinated to three N-atoms of histidine residues, and a hydroxo group bridged between the two Cu(II) ions in the oxidized state. The catalytic activity of model dicopper complexes is dependent on factors such as metal-metal distance, electronic and steric properties of coordinated ligands, and donor type. Monocopper analogues are scarce, but their synthesis is simpler and allows for systematic changes in structure. Recent research indicates that distorted square pyramidal monocopper(II) complexes with labile binding sites are important for simulating the active sites of catechol oxidases. This investigation aims to synthesize new tetradentate tripodal ligands containing N₃O, N₂O₂, N₂SO, N₄, and N₃S donors. These tripodal ligands will be used to prepare monocopper(II) complexes of the type [Cu(N₃O)Cl], [Cu(N₂SO)Cl], [Cu(N₂O₂)], [Cu(NSO₂)], [Cu(N₂SO)Cl], [Cu(N₄)Cl]Cl, [Cu(N₄)](ClO₄)₂, [Cu(N₃S)](ClO₄)₂, [Cu(N₃S)](ClO₄)₂, [Cu(N₃S)](ClO₄)₂, [Cu(N₃O)]₂(ClO₄)₂, [Cu(N₂O₂)]₂, [Cu(NSO₂)]₂]₂. The X-ray crystal structure of the complexes will be determined, and their catalytic ability towards the oxidation of catechol will be evaluated by electronic spectra in different solvents and buffer solutions. Kinetic studies will be carried out using a diode array, and a possible mechanistic cycle will be proposed based on the experimental results.