Spectroscopic studies of the hydrogen bonded charge transfer complex of 2-aminopyridine with π-acceptor chloranilic acid in different polar solvents

摘要

Hydrogen bonded charge transfer complex (HBCT) between 2-aminopyridine (2AP) as electron donor, hydrogen bond acceptor, with chloranilic acid (CHA) as the π-electron acceptor, hydrogen bond donor, has been studied spectrophotometrically in the polar solvents acetonitrile (AN), methanol (MeOH) and ethanol (EtOH). The stoichiometry of the complex has been identified by Job's and photometric titration methods to be 1:1. The Benesi-Hildebrand equation has been applied to estimate the formation constant (K_(CT)) and molar extinction coefficient (ε). It was found that the value of K CT is larger in methanol than those in acetonitrile or ethanol. The results were interpreted in terms of Kamlet-Taft α and β solvent parameters. Furthermore, the data were analyzed in terms of standard free energy change (ΔG°), oscillator strength (f), dissociation energy (W), transition dipole moment (μ) and ionization potential (IP). Also, the solid HBCT-complex was synthesized and characterized by using elemental analysis and FTIR spectroscopy.