Catecholase and phenoxazinone synthase activities of a ferromagnetically coupled tetranuclear Cu(ii) complex

Abstract

A crystallographically characterized tetranuclear Cu(II) complex [Cu^II₄(L)₄] (1) [H₂L = N-(2-hydroxyethyl)-3-methoxysalicylaldimine] is found to show overall ferromagnetic exchange coupling. Complex (1) mimics the catalytic activity of the plant enzyme catechol oxidase by oxidising 3,5-di-tert-butylcatechol to its corresponding quinone in methanol and dichloromethane medium in the presence of aerial oxygen. The reaction follows Michaelis–Menten enzymatic reaction kinetics with turnover numbers (K_cat) 6.99 × 10³ and 1.85 × 10³ h⁻¹ in methanol and dichloromethane, respectively. 1 is also phenoxazinone synthase active in methanol medium with a turnover number of 1.21 × 10⁵ h⁻¹.