Spectrophotometric and thermodynamic studies on the 1:1 charge transfer interaction of several clinically important drugs with tetracyanoethylene in solution-state: Part one

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.