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

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.