Coumarin Based Hydrazone as an Antioxidant and Sensor for Cupric Ion: Spectroscopic and Computational Studies

Abstract

A coumarin based hydrazone (CH) has been synthesised and characterised through 1H NMR, FTIR, UV‐Vis spectroscopy and CHN analysis. Using UV‐Vis and time dependent density functional theory, the antioxidant activity of CH against 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical and sensing properties towards various transition metal ions were studied. CH selectively binds to Cu2+ ion as compared to other transition metal ions such as Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+. From Benesi‐Hildebrand plot, the binding constant of CH for Cu2+ ion: 6×104 M−1 with lower limit of detection 31 μM is obtained. The CH‐Cu2+ complex is more stable as compared to the free form of the CH molecule. The stoichiometry ratio for CH‐Cu2+ complex is 2 : 1. CH quenches the DPPH radical through proton transfer mechanism with IC50 is 25 μM.