Synthesis and spectroscopic characterization of charge transfer complexes of the donor hesperidin and π-acceptors; 2,3-dichloro-5,6-dicyano-1,4- benzoquinone and tetracyanoethylene

Abstract

The interactions between a biologically active flavonoid, hesperidin (HESP) and two of the most known π- acceptors DDQ and TCNE were investigated leading to two new charge transfer complexes (CTC). UV-Visible spectrophotometry was used to follow the reactions in solution in methanol and ethanol as solvents. Infrared and NMR spectrophotometry was used to characterize the products formed in the solid state reactions.The)1:1(stoichiometry of formed charge transfer complexes (HESP-DDQ and HESP-TCNE) was confirmed by Molar ratio method and Benesi-Hildbrand equation was used to calculate the formation constants KCT and the molar extinction coefficient ɛCT of the formed CTC.CTC formed in the reaction of hesperidin with π-acceptors DDQ and TCNE showed high formation constants KCT. KCT values for both CTC formed in ethanol are higher than those formed in methanol and those found for the HESP-DDQ CTC were higher than those of HESP-TCNE.Our results suggest the formation of stable CT complexes of hesperidin with π-acceptors DDQ and TCNE.