Experimental and theoretical insights into the photophysical and electrochemical properties of flavone-based hydrazones

A small library of flavone-based hydrazones has been designed, synthesized and characterized. In this context, thirteen flavone hydrazones (3a-3 m) were synthesized by the acid-catalyzed condensation of flavone with 2,4-dinitrophenylhydrazine (2,4-DNPH) and characterized by different spectral techniques (IR, UV-Vis, NMR and mass spectrometry). The electrochemical, photophysical and theoretical investigations of such type of compounds are hitherto unknown. The electrochemical behavior of these hydrazones at a platinum electrode has been analyzed by cyclic voltammetry (CV) and was investigated at 20 0, 10 0 and 40 mVs(-1) in acetonitrile (CH3CN). These hydrazones showed a quasi-reversible redox reaction. The oxidation-reduction reactive sites of these derivatives were located via geometry optimization using density functional theory (DFT) at the B3LYP/3-21 g in the Guassian-09 level of theory. Moreover, the target compounds exhibited interesting fluorescent properties. Owing to their excellent photophysical and redox results, a detailed structure-property relationship was established to assess the substituents impact and their position on the physicochemical and electronic properties. All the experimental results were in accordance with the computational studies. (c) 2021 Elsevier B.V. All rights reserved.