A mononuclear Cu(ii) complex as a functional mimic of both catechol oxidase and phenoxazinone synthase

Abstract

A mononuclear penta-coordinated Cu(II) complex [CuLCl₂(H₂O)] (1) [where L = 2-benzoylpyridine imine] has been synthesized by a solvothermal process using 2-benzoylpyridine. The characterization of the complex has been carried out by several spectroscopic methods. Single crystal X-ray diffraction data reveal that the compound crystallizes in the monoclinic space group C₂/c, where a = 29.4663(17) Å, b = 10.4668(5) Å, and c = 8.6344(5) Å. Complex 1 exhibits significant catalytic oxidation activity toward both substrates, specifically converting 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) and o-aminophenol to 2-amino-3H-phenoxazin-3-one (phenoxazinone). This behavior efficiently mirrors the activities of enzymes such as catechol oxidase and phenoxazinone synthase. Notably, we harnessed atmospheric oxygen to drive the oxidation of the aforementioned model substrates, achieving impressive turnover numbers of 193 h⁻¹ and 1077 h⁻¹ for 3,5-DTBC and o-aminophenol respectively. These promise for advancing research in the realm of multi-enzymatic functional mimics. This innovative compound opens avenues for exploring its potential applications and broadening our understanding of synergistic enzymatic activities within a single mononuclear complex.