Revista de Ciencias Químicas

The single crystals of a Schiff base, N-(5-chlorosalicylidene) aniline suitable for X-ray diffraction were grown by slow evaporation from its ethanol solution. The geometrical, supramolecular features, energetics and biological activity of the title compound were analysed through a combined experimental and theoretical approach. The compound crystallizes in orthorhombic system with the space group Pca21. The unit cell parameters area=12.391 (6) Å, b=4.5223 (18) Å, c=19.514 (8) Å, α=β=γ=90.00°. V=1093.5 (8) Å3, Z=4, Dx=Mg m-3 and μ=0.32 mm-1. The crystal packing is mainly stabilized by dispersion forces from short H…H contacts. Also an intramolecular N-H…O hydrogen bonding is observed. For the optimised geometry, the HOMO-LUMO energy gap (7.071 eV) reflects the chemical activity. The compound is expected to have moderate hydrophilicity and hydrophobicity. Hence, have moderate permeability across cell membrane. Bioactivity scores suggest weakly bioactive nature of the compound.

Herein, we report the successful fabrication of a series of mechanically flexible poly (vinyl alcohol) (PVA) nanocomposite films with varying amounts of lithium doped stannous oxide (Li0.4Sn0.8O) nanofillers (i.e., 0.0, 0.5, 1.0, 2.0 and 4.0 wt %) by mechanical shearing followed by film casting. The structural characterizations (FTIR) ascertain the success of lithium doped stannous oxide integrations with PVA matrix. While, electronic spectral studies sheds light on the changes in electronic band structure leading to a gradual decrease in optical band gaps associated electronic transition from valence band to conduction band. The UV-visible transmittance study substantiates the ability of nano fabricated polymeric films to efficiently shield UV radiations, in particular UVA radiations and thereby act as highly flexible and visible transparent UVA protective coatings.

The research work presents the development of a mathematical model for predicting the diffusion of pH, salinity and conductivity in a stagnant water environment. The model was formulated from the basic principle of mass and momentum concept which was resolved to obtain an ordinary differential equation of y y p c (D c ) (VC) k t y ∂ ∂ ∂ ∂ ∂ ∂ − = − − ∂ ∂ . A mathematical tool known as the least square method was applied to resolved the differential equation to a quadratic equation of the form; C=Dd2+Vd+kp. Five water samples were collected at a depth of ≤ 5 cm, 15 cm, 30 cm, 45 cm, and 60 cm, in the vicinity of the Asphalt plant Company, located at Enito 3, in Ahoada West L.G.A of River State. The samples were analyzed to determine their physiochemical parameters. Experimental data obtained from the analysis were fitted into the model to obtain their diffusivities and velocities of the parameters upon the influence of contaminants. Concentrations of the contaminants at the various depths were simulated and the polynomial of the curve was also established to ascertain the validity of the developed model. Simulated results from the model were compared analytically and graphically with the experimental and validated result as presented in the work. The results obtained show a reasonable level of agreement which is an indication of the reliability of the developed model for predicting the contaminant diffusion in stagnant water.

In the present study the emphasis was given on two points, one is find out the effective extractants solvent and another is method of determination. Importance also was given on extraction ratio between solvent used as extractants and the amount used or dilution of the sample, shaking time and the incubation period on the basis of which after shaking how much time is required for settle down the solution just before titration/determination. The better result was obtained in 45 minutes to one hour after extraction was completed. Among three extractants, determination of elemental sulfur (ES), acetone can be used as an effective extractant for both S-rich fertilizer and soil sample (% recovery values obtained were 99.0 and 97.0% respectively). On the contrary, the % recoveries with toluene and xylene the values obtained from S-rich fertilizer and S-rich soils were 97.0 and 93.0 and 92.0 and 87.0% respectively. Determination was done with titrimetric method. Colorimetric always time consuming, values obtained with spectrophotometer is sometimes variable and expensive due to using of power supply. In titrimetric method where a high degree of accuracy and precision is not required. It is rapid and suitable for routine analysis in laboratories without using specialized equipment.

Zeolite Y in the sodium form (NaY) was synthesized using amorphous silica ash derived from waste rice husks under hydrothermal conditions. Structural characterization of NaY before and after modification with ZnO and ZnS has been done using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption at -196 °C, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The effects of the Na2O/SiO2 and Si/Al ratios, aging temperature and crystallization time on the optimized synthesis of NaY were thoroughly investigated. Thus the regulated Na+ impurity concentration in the starting hydrogel was found to act as a template-assisted synthesis of zeolite NaY by the potential incorporation of Al atoms into the zeolite framework. Results of surface analyses indicate that the interactions of ZnO and ZnS with NaY zeolite are distinguishable and thus the higher interaction is observed for the latter. While ZnII has experienced electrostatic bonding interaction with the framework oxygen atoms, creation of mesopores in NaY due to local destruction of the zeolite lattice around the growing ZnS particles was evidenced. Wonderfully, ZnS/NaY exhibited a high performance in prohibiting the growth of Escherichia coli (E. coli) and negligible from P. Aeruginosa, and these important features make it a potential candidate as an antimicrobial agent for controlling implant-related infections.

The synthesis, spectroscopic and structural characterization of Rh(I) ferrocenyl N-heterocyclic carbene complexes are described. The in situ deprotonation of the imidazolium salts with KOBut and subsequent complexation to rhodium(I) proved to be an efficient route for their synthesis yielding good too excellent yields. The X-ray crystal structure of bromo(η4-1,5-cyclooctadiene)(1-ferrocenyl-3-propyl-1H-imidazol-2-ylidene)rhodium(I) was obtained and reveals substitution disorder of a bromine and``  chlorine atom on Rh(1) in the ratio of 0.96/0.04.

A rapid, precise and reliable LC-MS/MS method has been developed for the identification and characterization of stressed degradation products of Tetrabenazine. Tetrabenazine is a drug, for the symptomatic treatment of hyperkinetic movement disorder. Tetrabenazine works mainly as a VMAT inhibitor. It promotes the early metabolic degradation of monoamines, in particular the neurotransmitter dopamine. Tetrabenazine was subjected to hydrolysis acidic, alkaline, neutral peroxidation, light and thermal stress conditions as per ICH-specified conditions. The drug showed degradation under peroxidation, thermal, acid and base hydrolysis stress conditions. However, it was stable to neutral stress conditions and light degradation. A total of 4 degradation products were observed and the chromatographic separation of the drug and its degradation products were achieved on Inertsil ODS-3V 150 mm × 4.6 mm, i.d., 5 μm column using 0.01 M ammonium acetate and ACN in the ratio of 640:360 as mobile phase-A and 900:100 ratio of ACN:Water as mobile phase –B. The degradation products were characterized by LC–MS/MS and its fragmentation pathways were proposed. Probable possible structures were drawn based on parent and daughter molecular ions.

Buried pipelines and steel structures passes or existed through different kind of sediments and saline water. This paper aims at optimize the best conditions to protect the buried pipelines from corrosive environments. Two ponds are selected for this study because of the big difference in chloride contents. The ponds were subjected to chemical, mineralogical, electrochemical analysis and the moisture content is also considered in this study. The results proved that mild steel is probably used in pond 1 at moisture content of 150% but in case of pond 4 mild steel is totally not recommended in all moisture content.

In the present study, carbonization method using mineral acids at elevated temperature. The potential of chemically carbonized palm trunk charcoal (PTC) for the effective removal of Cr(VI) ions from aqueous solution has been investigated in batch experiments. The sorption kinetics at pH=1.5 and the sorption isotherms at different pHs were studied. Chromium concentration was analyzed spectrophotometrically using 1,5-diphenylcarbazide. In order to the maximal adsorption at pH 1.5 was 24.7 mg g-1. The equilibrium adsorption capacity of PTC increases (4.99 to 24.7 mg g-1) as the initial Cr(VI) concentration increases (10-50 mg L-1). The adsorption behavior of Cr(VI) is best described by the pseudo-second order model and the calculated equilibrium capacity (15.6 mg g-1) agree with the experimental value (14.75 mg g-1). The equilibrium data were well fitted by the Langmuir isotherm model by revealing the maximum sorption capacity of PTC (24.7 mg g-1). The mechanism of adsorption was also studied using Fourier transform infrared (FTIR) spectroscopy. The bond of Cr(VI) to the functional groups of charcoal seems to be irreversible in the case of dried Cr(VI) saturated charcoals.