Abstract
In our previous work, we highlighted the thermodynamic and spectroscopic characteristics of the 1:1 charge transfer (CT) complexation of TCNE acceptor with various medically important drugs. Continuing that work, we further examine drugs that react with the TCNE acceptor via a 1:2 interaction. The examined drugs are atenolol, quinidine, cimetidine, reserpine, and levofloxacin. We aimed through this study to: i) make the spectrophotometric and thermodynamic data of the examined drugs, both initially and when reacted via a 1:2 M ratio with the TCNE acceptor, available to use in the determination or detection of these drugs in pharmaceuticals and other environments; and ii) compare the mode of interactions and the spectrophotometric and thermodynamic properties between drugs that react via a 1:1 or 1:2 ratio with the TCNE acceptor. To achieve these aims, the five examined drugs were reacted with TCNE in acetonitrile (MeCN) solvent at room temperature. Several thermodynamic and spectroscopic data were experimentally estimated using the van't Hoff and the Benesi–Hildebrand equations and discussed.
Electronic absorption spectrum of the CT product that formed form the reaction of drug Qui with TCNE acceptor in MeCN solvent. [Display omitted]
•CT complexes were obtained by the reaction of different drugs with TCNE.•Electronic spectra show a very strong absorption band at 405 nm with two heads.•Experimental data suggest that the complexation occurs via n→π* and π→π* interactions.•The van‘t Hoff plot was employed to determine the thermodynamic data.•The Benesi–Hildebrand plot was employed to determine the spectroscopic data.