JOURNAL OF PHYSICAL AND THEORETICAL CHEMISTRY
Year:2013 | Volume:10 | Issue:1|Papers Count:8

In this paper, the structural properties of the B30N20 molecule have been investigated at B3LYP/6-31G (d) level of theory. The optimized structure and electronic properties calculations for the studied molecule have been performed using Gaussian 03 program. A mathematical equation of third degree was exploited for the correlation and exchange energy with the number of primitives. The Natural Bonding Orbital (NBO) analysis were performed on the B30N20 at the B3LYP/6-31G level of theory.

In this paper, the effect of penicillin G drug as a green corrosion inhibitor on mild steel in 1.0 M hydrochloric acid solution has been investigated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques. The inhibition efficiency was found to increase with increasing inhibitor concentration. Potentiodynamic polarization measurements indicated that penicillin G is a mixed type inhibitor. Furthermore, it has been demonstrated that the electrochemical noise (EN) technique under open circuit conditions as the only truly noninvasive electrochemical method can be employed for the quantitative evaluation of corrosion inhibition. This can be done using the standard deviation of partial signal (SDPS) for calculation of the amount of noise charges at the particular interval of frequency, thereby calculate the inhibition efficiency (IE) of an inhibitor. These IE values show a reasonable agreement with those obtained from potentiodynamic polarization and EIS measurements.

An interaction potential at different orientation for the CH4 and CO2 complex was derived at the B3LYP level of theory and 6-31+G* basis sets. The potential energy surface was computed on some molecular geometries. The complete basis set limit of the interaction energies were fitted to well-known analytical functions. To determine the second virial coefficients B, U (r) is used to obtain the model’s parameters over the range of temperatures of interest.

In this paper we have down three theoretical study by using Monte Carlo simulation and Mm+, AMBER and OPLS force field. The calculations were carried out using Hyper Chem professional, release 7.01 package of program. first we have studied the interaction of H2 molecule and He atom with single-walled carbon nanotube at different temperature. For doing this study we placed H2 and He in the center and outside the nanotube, permitting them to close the nearest carbon atom from nanotube. Then we plotted the potential energy versus distance of interaction, and at minimum point of energy we calculated potential energy for physical adsorption process. Second we placed tow H2 molecules and tow He atoms at tow ends of nanotube separately, permitting them to close each other step by step then we calculated Ekin, Epot and Etot for H2---H2 and He---He interaction at different temperature. In another activity we added 2 to 100 H2 molecules and 2 to 100 He atoms across the nanotube and after each time increased the number of H2 and He we have estimated the potential energy, then we plotted the potential energy versus the number of H2 molecules and He atoms so that the shape of potential curve will be determined.

Over the past decade, the chemical behavior of flavonoids as antioxidants has become the subject of intense experimental research. Plants represent a main source of natural antioxidants that might serve as leads for the development of novel drugs. Malva sylvestris L. known to have various medicinal properties since several decade ago, were evaluated for their antioxidant compounds, Most of these bioactive properties correlated with antioxidant activity of phenolic compounds found in the plant, 11 phenolic composed were isolated from water leaf extract of Malva sylvestris L., the main phenolic acids identified in Malva sylvestris L. leave's are gallic, pyrogalllol, vanillic, synergic, cinnamic and chrisin acid. antioxidant and antiprotozoic activities quercetin is the major flavonoid in the human diet and has been reported for their radical scavenging effect. They have been proved to have potential preventive and therapeutic effects in many diseases. This study involves substitution of the functional group of methyl in the active site of some terpenoids isolated from Malva sylvestris L. with other functional groups such as F, Cl, and Br and calculations by keywords Opt, NMR, and Freq for optimization and chemical shift calculations and drive thermodynamic parameters including Enthalpy, Gibbs free energy respectively. The quantum mechanics (QM) calculations were carried out GAUSSIAN98 at NMR by using B3LYP methods with 6-31G basis set.

The thermodynamic functions such as enthalpy (H), Gibbs free energy (G) and entropy (S) of Pyrazole was theoretically studied at 5 different temperatures 25, 30, 35, 40 and 45oC by using Gussian o3, software. First, the structural optimization of isolated Pyrazole was done in the gas phase by appling the Density Functional Theory (B3LYP) level with 3-21G, 6-31G and 6-31+G (d) basis sets. Moreover, vibrational frequencies were calculated in gas phase on the optimized geometries at the same level of theory to obtain enthalpy, Gibbs free energy and entropy at 5 different temperatures. Finally the temperature effects on the thermodynamic functions were discussed.

A batch adsorption study was applied to investigate the adsorption of Pb2+ ions from aqueous solution by nanographene (nG).The adsorption percentage of Pb2+ions onto nG samples at different initial pH, contact time (tc), adsorbent dosage (mnG) and temperature (T) were investigated. The results showed that nG is an excellent adsorbent for Pb2+ ions removal from aqueous solutions with an adsorption percentage of up to 79.8% at initial Pb2+ concentration of 20ppm and temperature of 298K.The experimental data could be well described by the Freundlich and Langmuire isotherm model; thermodynamic parameters of adsorption process (DG0, DH0, DSo) were also evaluated. The overall adsorption process was exothermic and spontaneous in nature. The results indicate that Pb2+ions adsorption onto nG may be chemisorption.

This review reports recent advances in the field of polymer-layered silicate nano composites. These materials have attracted both academic and industrial attention because they exhibit dramatic improvement in properties at very low filler contents. Herein, the structure, preparation and properties of polymer–layered silicate nanocomposites are discussed in general, and finally the effect of clay nanoparticles on optical and Rheological properties of polymeric products were also discussed.