Spectroscopic characterization of charge transfer complexes of 2,3-diaminopyridine with chloranilic acid and dihydroxy-p-benzoquinone in polar solvent

Charge transfer (CT) complexes formed between 2,3-aminopyridine (2,3-DAP) as electron donor with the it-electron acceptors chloranilic acid (CHA) and dihydroxy-p-benzoquinone (DHBQ) were investigated spectrophotometrically in ethanol. Minimum-maximum absorbance method has been used for estimating the formation constants of the charge transfer reactions (K-CT). Job's method of continuous variation and photometric titration studies were used to detect the stoichiometric ratios of the formed complexes and they showed that 1:1 complexes were produced. The molar extinction coefficient (epsilon), oscillator strength (f), dipole moment (mu). charge transfer energy (E-CT), ionization potential (I-p) and the dissociation energy (W) of the formed complexes were estimated, they reached acceptable values suggesting the stability of the formed CT-complexes. The solid CT-complexes were synthesized and characterized by elemental analyses, H-1 NMR and FTIR spectroscopies where the formed complexes included proton and electron transfer. (C) 2013 Elsevier B.V. All rights reserved.