Investigation of electrochemical and spectroelectrochemical properties of some amino-substituted naphthoquinones (NQs)

The class of quinone compounds are excellent representatives of biologically redox-active compounds. Electron transfers such as in quinone compounds play important roles in the bioactivation of redox-active drugs, in their metabolism/catabolism, and targeted release at precise destinations and frequently promote their ligand–target interactions. Owing to the enthralling synthetic importance and pharmacological applications of 1,4-naphthoquinone derivatives, our interest is turned into a detailed electro- and photoelectrochemistry study of these pharmacophoric structures. Firstly, amino(substituted)-1,4-naphthoquinone (NQ) derivatives (2a-b, 3, 4a-b, 5, 6, 7, 8 and 9) were synthesized according to Michael addition mechanism. The exact structures of compounds were elucidated by spectroscopic methods such as FT-IR, ¹H-/¹³C NMR, MS and microanalysis. Secondly, the electrochemical behaviors of NQ derivatives are determined with voltammetric and in situ UV–Vis spectroelectrochemical measurements. All synthesized NQ derivatives illustrate two reductions and one oxidation processes. Voltammetric analyses of the couples of the molecules indicate electrochemical reversibility of the reductions and electrochemical irreversibility of the oxidation couples. Substituent environments of NQ structure considerably influence the chemical reversibility of the redox processes.