Design, Synthesis, Structural Characterization and Comprehensive Electrochemical and In Situ Spectroelectrochemical Investigation of Heterocyclic Ring-Containing Quinone Derivatives

Abstract

Naphthoquinone derivatives (NQ) are an important class of functional materials widely used in various biological applications, such as active pharmaceutical ingredients and anticancer agents. NQ were synthesized, and their electrochemical properties were examined in detail. The rationale for selecting heteroatom ring substituents is to facilitate electron transfer reactions in NQ and ensure they occur reversibly at lower potentials. The electrochemical and optoelectronic responses of NQ were determined with different voltammetric and spectroelectrochemical (SEC) techniques. The electrochemical analyses indicated that all compounds illustrated common couples that were influenced by the type of substituents and the solvent of the electrolyte. While NQ had reversible couples, subsequent chemical reactions observed after the couples influenced the chemical stability of the anionic species. The tendency of the chemical reactions was also influenced by the substituents and the solvent of the electrolyte. The intense spectral changes during the reduction reactions caused prominent color changes, which indicated electrochromic functionality of these quinones. These voltammetric responses showed that the preferred redox responses can be tailored by using proper substituents on the NQ ring. Here, the fact that the NQ exhibits reversible reduction properties at low potentials suggests that it can be used as the best oxidant among these compounds.