Functional mimic for catechol oxidase and phenoxazinone synthase: Structural, spectral, electrochemical and catalytic properties of mononuclear copper(II) complex

Abstract

A promising bioinspired metallocatalyst [Cu(L1)2(L2)] (L1 = P-hydroxybenzoic acid, L2 = N1,N1-dimethylpropane-1,3-diamine) has been produced and characterized in accordance with reports. In the octahedron arrangement around the copper ion, the elongation along one axial direction and one equatorial direction results in a distorted geometry Molecular assembly shows both inter and intra molecular H-bonding along with CH---π interactions evident from the Hirhsfeld surface analysis. The fingerprint plot discloses the relative contribution of percentage of intermolecular contacts (H⋯H, C⋯H and O⋯H) in the complex. The EPR, CV, and UV analyses collectively support that the complex exhibits such activity via oxygen dependant enzymatic radical pathway. Furthermore, these activities are observed under fully aerobic conditions in which 3,5-di-tert-butylcatechol (3,5-DTBC) and 2-amino phenol (2-AP) are used as model substrates. Michaelis-Menten analysis derived from the pseudo first-order reaction kinetics established that this complex shows extremely high catalytic activity towards 3,5- DTBC and 2-AP (Kcat 1.729 × 105 h−1 and 0.260 × 105 h−1). The suggested mechanism has been supported by UV spectra data in which formation of hydrogen peroxide by observing the appearance of spectral band at λmax 353 nm indicates the active participation of molecular oxygen in the catalytic process.