Spectroscopic and physicochemical studies on the charge transfer complex of dextromethorphan drug with iodine

Abstract

The drug dextromethorphan had been shown to form a charge transfer (CT) complex of 1 : 1 stoichiometry with iodine in different solvents. The enthalpy and entropy of formation of this complex had been determined by estimating the formation constant spectrophotometrically at three different temperatures. The solvent variation study on the intermolecular CT complex formation revealed that the intensity of the interaction increases with decrease in relative permittivity of the medium. Transition energy, oscillator strength and dipole moments of the complex as well as the ionization potential of the donor have been computed from spectroscopic data and discussed. The experimentally measured ionization potential of the donor drug closely agrees with that computed theoretically using MOPAC (PM3) semi-empirical method.