Azolylphenanthridine-ligated Cu(II) catalyst for electrochemical oxidation of cholesterol in aprotic medium

The synthesis of original 6-(azol-1-yl)phenanthridine ligands and a copper(II) complex based on them is reported. Comprehensive studies of the structural, physicochemical, and electrocatalytic properties for the selected 6-(1H-pyrazol-1-yl)phenanthridine-containing H-pyrazol-1-yl)phenanthridine-containing coordination compound have been carried out. The latter has demonstrated pronounced electrochemical and electrocatalytic activities in the enzyme-free cholesterol oxidation in DMSO. A six-stage mechanism including electrocatalytic reduction of cholesterol and subsequent oxidation of its reduction products has been proposed and underpinned by quantum mechanical considerations. Obtained analytical characteristics of the enzyme-free cholesterol oxidation (LoD 0.0032 mM, detectable concentrations 0.01-0.40 mM) open a prospect towards the investigated complexes to be applied as sensitive elements of portable electrochemical platforms for the point-of-care diagnostics.