Synthesis, characterization and spectrophotometric studies of charge transfer interaction between donor imidazole and π acceptor 2‚4-dinitro-1-naphthol in various polar solvents

Abstract

A novel charge transfer complex has been obtained between good donor imidazole (IZ) and π acceptor 2,4-dinitro-1-naphthol (DNN) in various polar solvents such as chloroform, ethanol, acetonitrile and DMF at room temperature. The molecular composition of the formed CT complex was recognized in 1:1 with the maximum absorption band. The high value of the formation constant confirmed the stability of the CT complex, which was estimated using Benesi-Hildebrand equation. The solid complex was synthesized and characterized using FTIR, TGA-DTA, powder XRD, 1H NMR, UV–visible and ESI-mass spectra. Various important parameters such as formation constant (KCT), molar extinction coefficient (εCT), and Standard Gibbs free energy (ΔG°), oscillator strength (f), transition dipole moment (μEN), resonance energy (RN) and ionization potential (ID) were calculated using Benesi-Hildebrand equation in different polar solvents. CT complex was formed by proton transfer from DNN to IZ showing N+HO– bonding. Understanding the interaction between donor and acceptor able to interpret the donor–acceptor interaction and acting mechanism between these compounds. The formation constants of the CT complex were determined in different polar solvents from which ∆G° formation of the complexes was estimated.