Ultrasonic and optical studies on charge transfer complexes of p-chloranil with certain aromatic hydrocarbons in DMSO at 303.15 K

Abstract

Ultrasonic investigation has been carried out on six ternary systems to establish the complex formation between p-chloranil (acceptor) and six aromatic hydrocarbons (donors), namely, benzene, toluene, o-xylene, m-xylene, p-xylene and mesitylene in DMSO medium at 303.15 K and at atmospheric pressure. Studies were carried out in the concentration range of 0.002 to 0.02 M of acceptor and donor with equimolar concentration of the two components in solution. The trend in the acoustical parameters and magnitude of excess thermo acoustical parameters has been used to identify the existence of strong intermolecular interaction through charge transfer complex formation. The formation of 1:1 complex was also confirmed by UV–Visible spectroscopic method at 303.15 K in these systems. It may be pointed out that the formation constants of the charge transfer complexes determined by Benesi–Hildebrand (spectroscopic) and Kannappan (ultrasonic) methods show similar trend and well establish the influence of structural aspect of the donor aromatic compounds on the stability of charge transfer complexes.