Triazole-tethered naphthalimide-ferrocenyl-chalcone based voltammetric and potentiometric sensors for selective electrochemical quantification of Copper(II) ions

Abstract

• A ferrocene based TNFC was synthesized and found sensitive towards Cu 2+ . • UV, fluorescence, DFT, NMR and HRMS studies confirmed binding of TNFC with Cu 2+ . • TNFC exhibited voltammetric response towards Cu 2+ with LOD 0.09 µM. • TNFC -CPE showed a Nernstian slope of 30.0 mV/decade with LOD 0.79 µM. • TNFC -CPE was successfully applied for estimation of Cu 2+ in water and milk products. A triazole-tethered naphthalimide-ferrocenyl-chalcone ( TNFC ) derivative was synthesized and investigated for its electrochemical behavior with subsequent successful application as a receptor for the development of differential pulse voltammetric (DPV) and potentiometric sensors for quantification of Cu 2+ after receiving confirmatory evidences from UV–Vis, Fluorescence and DFT studies. Cyclic voltammogram of TNFC exhibited two redox peaks at +0.51 V and +0.59 V corresponding to ferrocene/ferrocenium ion redox couple in the potential range of 0–1.0 V vs Ag/Ag + . On addition of Cu 2+ , Cyclic voltammogram of TNFC shifted toward more positive potential (anodic shift), indicating the formation of TNFC -Cu 2+ complex. DPV sensor demonstrated a selective response towards Cu 2+ in the concentration range of 0–26 µM with detection limit of 0.09 µM. The TNFC modified carbon paste electrode (CPE) exhibited a selective response for Cu 2+ with Nernstian slope of 30.0 mV/decade in the concentration range of 1.0 × 10 −6 −1.0 × 10 −1 M and detection limit 0.79 µM. High binding constant (3.2 × 10 4 M −1 ) and negative value of Gibbs free energy (−25.69 kJmol −1 ) calculated using Benesi-Hildebrand (BH) equation confirmed the favorable complexation between TNFC and Cu 2+ which was also validated using 1 H NMR and mass spectrometry. The proposed TNFC- CPE was successfully utilized for quantification of Cu 2+ content in real samples of water and milk products.