UV–Vis, FTIR, 1H, 13C NMR spectra and thermal studies of charge transfer complexes formed in the reaction of Gliclazide with π- and σ-electron acceptors

Charge transfer interactions (CT) between a gliclazide (GLC) donor and a picric acid (PA) π acceptor or iodine σ acceptor, were studied in a chloroform solution and in the solid state. UV–vis spectroscopy elucidated the formation of the complexes, and allowed determination of the stoichiometry, stability constants (K), and thermodynamic quantities (ΔG°, ΔH°, and ΔS°), and spectroscopic properties such as the molar extinction coefficient (εCT), oscillator strength (f), transition dipole moment (μEN), and ionization potential (Ip). Beer's law was obeyed over the 2–8 and 4–12 μg mL−1 concentration ranges for GLC with PA (method A) and I2 (method B), respectively, with correlation coefficients of 0.9986 and 0.9989. The limits of detection (LOD) and limits of quantification (LOQ) have also been reported. The 1:1 stoichiometric CT complexes were synthesized and characterized by FTIR, 1H, and 13C NMR spectroscopy. The results indicated a favorable proton migration from PA to the donor molecule, and an interaction between the NH of GLC and iodine. Thermogravimetric analysis techniques (TGA/DTA) and differential scanning calorimetry (DSC) were used to determine the thermal stability of the synthesized CT complex. The kinetic parameters (ΔG*, ΔH*, and ΔS*) were calculated from thermal decomposition data using the Coats-Redfern method. [Display omitted] •CT-complexes between GLC and PA or I2 are obtained and characterized with UV-vis, FTIR, 1H, 13C NMR, and thermal analysis.•The results indicated a favorable proton migration from PA to the GLC, and an interaction between the NH of GLC and iodine.•The thermodynamic, kinetic and spectroscopic parameters, LOD and LOQ are calculated.