Abstract
Charge transfer complex formation between 2-aminopyridine (2AP) as the electron donor with 2,5-dihydroxy-p-benzoquinone (AHBQ) as the pi-electron acceptor has been investigated spectrophotometrically in acetonitrile (AN) and 50% acetonitrile + 50% 1,2-dichloroethane (V/V), (ANDC). The stoichiometry of the complex has been identified by Job's method to be 1:1. The Benesi-Hildebrand equation has been applied to estimate the formation constant (K (CT)) and molecular extinction coefficient (epsilon). It was found that the value of K (CT) is larger in ANDC than in AN. The thermodynamic parameters are in agreement with the K (CT) values in that the enthalpy of formation (-I"H) has a larger value in ANDC than in AN, suggesting higher stability of the complex in ANDC. The complex formed between 2AP and DHBQ has been isolated as a solid and characterized using elemental analysis, FTIR, and H-1 NMR measurements. Moreover, it has been found that the formed complex involves proton transfer in addition to charge transfer.