Abstract
The occurrence and environmental fate of pharmaceuticals represents a rising and significant public concern worldwide. To provide basic data that can be used to detect and determine several drugs in such environments, this work examines the charge transfer (CT) interaction of tetracyanoethylene (TCNE) as a π-acceptor with eight drugs by spectrophtometry in acetonitrile (MeCN). All of the drugs formed stable yellow compounds with TCNE. The results show that the complexation stoichiometry of TCNE/drug is 1:1. Several spectroscopic and thermodynamic parameters were estimated using the Benesi–Hildebrand and Van't Hoff's equations. Very strong linear correlations were observed between the thermodynamic parameter. The IR data suggest that the complexation between TCNE and drugs occurs via n→π* and/or π→π* interactions.
The investigated drugs differ in their spectral absorption response towards a TCNE acceptor. Some drugs show one strong absorption band and one maximum band, while others show two maxima. The splitting in the latter could be attributed to the existence of two interaction modes within the complex (n→π* and π→π*). [Display omitted]
•CT complexes were obtained by the reaction of different drugs with TCNE.•Several spectroscopic and thermodynamic data were evaluated.•Highly linear correlations between the thermodynamic data were observed.•IR data suggest that the complexation occurs via n→π* and π→π* interactions.