Siti Aishah Hasbullah

Synthesis, X-ray, NMR, FT-IR, UV/vis, DFT and TD-DFT studies of N-(4-chlorobutanoyl)-N'-(2-, 3- and 4-methylphenyl)thiourea derivatives.

A new isomers of thiourea derivatives, namely N-(4-chlorobutanoyl)-N-(2-methylphenyl)-thiourea (1a), N-(4-chlorobutanoyl)-N-(3-methylphenyl)thiourea (1b) and N-(4-chlorobutanoyl)-N-(4-methylphenyl)thiourea (1c) have been synthesized by refluxing mixture of equimolar amounts of 4-chlorobutanoylisothiocyanate with 2, 3 or 4-toluidine, respectively. The three isomers were characterized by spectroscopic (UV/vis, FT-IR and NMR) and X-ray crystallography techniques. To investigate the isomerization effect on spectroscopic data, DFT and TD-DFT calculations have been carried out using five hybrid functionals (B3LYP, B3P86, CAM-B3LYP, M06-2X and PBE0) to predict UV/vis absorption bands (n→π∗ and π→π∗), (1)H and (13)C NMR chemical shifts, FT-IR vibration modes and X-ray parameters (bonds, bond angles and torsion angles) for 1a, 1b and 1c isomers. The results showed that the isomerization effect is significant on λ(MAX) absorption bands, while for IR and NMR the effect is negligible. In accordance with previous studies, B3LYP, B3P86 and PBE0 gave the most reliable to predict the excitation energies of thiourea derivatives.

Conductometric Studies of the Thermodynamics for Complexation of 1,1-Diethyl-3-(4-methoxybenzoyl)thiourea and Cobalt(II) Cation in Aqueous Binary Mixtures of Polar Organic Solvents

The complexation reaction of Co2+ (M) and the 1,1-diethyl-3-(4-methoxybenzoyl)thiourea (L) ligand in the binary mixtures: acetonitrile–dimethylsulfoxide (MeCN–DMSO), acetonitrile–dichloromethane (MeCN–DCM), water–dimethylsulfoxide (H2O–DMSO) and acetonitrile–water (MeCN–H2O), was investigated using a conductometric method at temperatures of (288.15, 298.15, 308.15 and 318.15)xa0K. In all cases, the conductance data showed that the stoichiometry of the neutral complex formed between M and L is 1:3 [M:3L], which indicates that the Co2+ ion was oxidized to Co3+ during the reaction. The best estimate of the stability constant, log10xa0Kf,xa0=xa03.31 for the [CoL3] complex, was observed with the MeCN–DCM (20:80xa0%) binary mixture at 298.15xa0K. The values of the thermodynamic parameters (i.e.,

Synthesis and characterization of bis-thiourea having amino acid derivatives

Delta G_{text{c}}^{^circ }

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

ΔGc∘ and

2,4-Di­chloro-N-[eth­yl(2-hy­droxy­eth­yl)carbamo­thio­yl]benzamide

Delta S_{text{c}}^{^circ }

Phosphate sensor based on immobilized aluminium-morin in poly (glycidyl methacrylate) microspheres

ΔSc∘) for the formation of the [CoL3] complex were obtained from the temperature dependence of the stability constant via van’t Hoff plots. The results show that, in most cases, the [CoL3] complexes are enthalpy destabilized but entropy stabilized. The values and signs of the thermodynamic parameters are affected by the nature and composition of the mixed solvents but are independent of the temperature.