Preparation, spectroscopic and antibacterial studies on charge-transfer complexes of 2-hydroxypyridine with picric acid and 7,7′,8,8′-tetracyano-p-quinodimethane

The reactions of electron acceptors such as picric acid (HPA) and 7,7',8,8'-tetracyano-p-quinodimethane (TCNQ) with 2-hydroxypyridine (HPyO) have been investigated in EtOH at room temperature. Based on elemental analysis and IR spectra of the solid CT-complexes along with the photometric titration curves for the reactions, the data obtained indicate the formation of 1:1 charge transfer complexes [(H2PYO)(PA)] and [(PYO)(HTCNQ)], respectively. The infrared and H-1 NMR spectroscopic data indicate a charge transfer interaction associated with a proton migration from the acceptor to the donor followed by intramolecular hydrogen bonding in [(H2PyO)(PA)] complex. Another charge transfer interaction was observed in [(PyO)(HTCNQ)] complex. The formation constants (K-CT) for the CT-complexes are shown to be strongly dependent on the type and structure of the electron acceptors. Factors affecting the CT-processes and the kinetics of thermal decomposition of the complexes have been studied. The CT complexes were screened for their antibacterial activities against selected bacterial strains. (C) 2015 Elsevier B.V. All rights reserved.