Mekki Kadri

Charge transfer complexes of 4-isopropyl-2-benzyl-1,2,5-thiadiazolidin-3-one1,1-dioxide with DDQ and TCNE: experimental and DFT studies

The charge transfer complexes of the donor 4-isopropyl-2-benzyl-1,2,5-thiadiazolidin-3-one1,1-dioxide (SF) with π acceptors 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and tetracyanoethylene (TCNE) have been studied spectrophotometrically in chloroform and methanol at room temperature. The results indicated the formation of CT-complexes with a molar ratio of 1 : 1 between donor and each acceptor. The physical parameters of the CT-complexes were evaluated using the Benesi–Hildebrand equation. The data were analyzed in terms of their stability constant (K), molar extinction coefficient (eCT), thermodynamic standard reaction quantities (ΔG0, ΔH0, ΔS0), oscillator strength (f), transition dipole moment (μEN) and ionization potential (ID). The experimental studies were complemented by quantum chemical calculations by the time-dependent density functional theory (TD-DFT) at the B3LYP level. The theoretical UV visible and FT-IR spectra were compared with those obtained experimentally. The first order hyperpolarizability (β0) and related properties (α0 and Δα) are calculated using the B3LYP method on the finite-field approach. The Mulliken charges, MEP calculations, the electronic properties, HOMO and LUMO energies and NBO analysis were performed on an optimized charge transfer complex of SF-DDQ.

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). Beers 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.

The inclusion interaction between an anti inflamatory with β-cyclodextrin

The inclusion interactions between β-cyclodextrin (β-CD) and diclofenac (DCF) were simulated using the semiempirical PM3 and ONIOM (B3LYP/3-21g: PM3) methods. The modeling results showed that the most stable geometry of DCF into β-CD complex is B orientation inclusion, in which the phenyl acetate moiety is included inside the hydrophobic cavity of β-CD. The results showed that the binding energy (BE) and total stabilization energy (EONIMO) of B orientation are lower than A orientation, indicating that the B orientation is more stable than the A orientation, Furthermore, it can be deduced from the results obtained by NBO analysis that the main driving forces of DCF/β-CD are weak hydrogen bonding interaction.