Spectrophotometric and Thermodynamic Studies of Charge Transfer Complexes of 8-Hydroxyquinoline with π Acceptor p-Nitrophenol in Different Solvents

The charge transfer complexes of the donor 8-hydroxyquinoline (8HQ) with acceptor p-nitrophenol (PNP) have been studied spectrophotometrically in various solvents. The results indicate the formation of CTC in less Polar solvent to be more and also CT shifted to longer wavelength with increased polarity. The stoichiometry of the complex was found to be 1:1 by straight line method between donor and acceptor with maximum absorption bands. The data are discussed in terms of molar extinction coefficient (epsilon CT), equilibrium constant (Formation constant), resonance energy (RN), free energy (Go), ionization potential (ID), and oscillator strengths (f). The results indicate the formation constant (KCT) for the complex to be dependent of the nature of electron acceptors, donors, and polarity of solvents.