In this work, the N,N′-dipyridoxyl(1,2-diaminocyclohexane) [=H 2 L] Schiff-base ligand and its square complex [Cu(L)] are newly synthesized and characterized by IR, mass spectroscopy, 1 H NMR, and elemental analysis. The ful optimization of geometries, the 1 H NMR chemical shifts (for the H 2 L) and their vibrational frequencies are calculated using the density functional theory (DFT) method. The optimized geometry of the ligand is not planar, but each of two pyridine rings and the cyclohexane moiety are in the separate planes. The tetradentate-dianionic L 2ligand occupies the four coordination positions of the square comlex in the N, N, O -, Omanner.

Excess molar volumes and the deviations in molar refraction of the N-formylmorpholine (NFM) + methanol, methanol+benzene, NFM +benzene, NFM +toluene, methanol + toluene binary systems and also for the ternary systems of NFM + methanol + benzene and NFM + methanol + toluene have been determined at 298.15 K and at atmospheric pressure, by measuring densities and refractive indices over the entire range of composition. These derived data of binary and ternary mixtures were fitted to Redlich-Kister and Cibulka equations for the binary and ternary systems. The ternary data were also compared with the predicted values using the binary contribution models of Tsao-Smith, Kohler and Radojkovicˇ.

The densities () and refractive indices (n D) of binary mixtures of acetonitrile with benzene, toluene, m-xylene and mesitylene including those of pure liquids, over the entire composition range expressed by mole fraction x 1 of acetonitrile were measured at temperatures (298.15, 303.15, 308.15, and 313.15) K under atmospheric pressure. From the experimental data, the excess molar volumes (E m V) and the deviations in refractive indices (Δn) were calculated. These results are fit to a Redlich-Kister type polynomial equation. The results indicate the presence of weak interactions between acetonitrile and aromatic hydrocarbon molecules. The deviations in E m V values follow the order toluene < benzene < m-xylene < mesitylene. The results are discussed in terms of the intermolecular interactions. Experimental Chemicals: Acetonitrile, mesitylene (Fluka AG, mole fraction purity > 0.998), benzene, toluene and m-xylene (Merck, mole fraction purity > 0.995) were used without further purification. All liquids were stored over freshly activated molecular sieves of type 4A (union Carbide). Doubly distilled water was used as the standard liquid with conductivity less than 0.05 µs cm 1. Apparatus and Procedure: The mixtures were prepared by mass and were kept in special airtight stopper glass bottles to avoid evaporation. The weightings were done using an electronic balance (model GR-202R, AND, Japan) with a precision of ± 0.01 mg. The uncertainty in the mole fraction was estimated to be less than ± 0.0001. The density measurements of the pure solvents and the mixtures were performed by means of an Anton Paar, model DMA 48, Graz, Austria with a precision of ±0.00005 g cm-3 , between 298.15 and 313.15 K. The DMA cell was calibrated with dry air and doubly distilled water at atmospheric pressure. The sample size was 0.70 cm 3 12 1 2

Potentiostatic polarization and weight loss methods have been used to investigate the corrosion behavior of carbon steel in sodium chloride solution at different concentrations (0.1, 0.4 and 0.6) M under the influence of temperatures ( 293, 298, 303, 308 and 313) K. The inhibition efficiency of the amoxicillin drug on carbon steel in 0.6 M NaCl has also been studied based on concentration and temperature. The corrosion rate showed that all salt concentrations ( NaCl solution) resulted in corrosion of carbon steel in varying ratio and 0.6 M of salt solution was the highest rate (50.46 g/m².d). The results also indicate that the rate of corrosion increases at a temperature of 313 K.. Potentiodynamic polarization studies showed that the examined inhibitor suppress both anodic and cathodic process and behave as mixed type inhibitor. The adsorption of amoxicillin was found to obey Langmuir isotherm model. Arrhenius equation and transition state theory were used to calculate kinetic and thermodynamic parameter. Results obtained showed that corrosion reaction of carbon steel in NaCl is spontaneous and there is a good agreement between the data got from the both techniques employed. SEM analysis was performed to study the film persistency of the inhibitor.