JOURNAL OF PHYSICAL AND THEORETICAL CHEMISTRY
Year:2012 | Volume:8 | Issue:4|Papers Count:10

The Density Functional Theory (DFT) and the Natural Bond Orbital (NBO) calculations based method B3LYP/6-31G were carried out to study the interaction of Dopamine with carbon nanotube. The nanotube used in this study, includes 60 C atoms (6, 6) type. Relative and formation energies of compounds, Muliken charges, occupancy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), the HOMO-LUMO band gap and the electronic chemical potential (m) were calculated. The NBO analysis showed there is a hyperconjugative interaction between Oxygen and Nitrogen lone-pair electrons of dopamine and s* or p* orbitals of carbon atom of nanotube. Results indicated that the composite between nanotubes and the Ncentered dopamine is more stable than O1-centered dopamine and both of them are stable than the single agent.

BCN compounds have been researched theoretically and experimentally widely. In this paper, we introduce the theoretical prediction of ternary B-C-N compounds. NMR spectroscopy was employed extensively to study these ternary nanostructures. We discuss the utilization of chemical shift information as well as ab initio calculations of nuclear shielding for H20B4C9N4 structure determination. We calculated B NMR and N NMR spectra with computational aspects of the NMR spectra using the gauge-invariant atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) methods at different DFT computational methods (B1LYP and LSDA), with a 6-31 G basis set at the GAUSSIAN 98 program package which are discussed. The purpose of this study is to carry out a more detailed analysis of the H20B4C9N4 as a new nanosemiconductor system.

Ethylammonium Propionate with high polarity and ionic conductivity was synthesized and characterized with 1HNMR and IR. This ionic liquid which is prepared from readily available starting material in high yield shows reasonably high at viscosity and heat stability up to 150oC. This Ionic Liquid is able to dissolve most of organic solvents due to the hydrogen interaction between Ionic Liquid and these solvents.

Sulforaphane, an isothiocyanate found in broccoli and other cruciferous vegetables, it is an antioxidant and anti-cancer agent, and reduces blood pressure, and also has anti-allergic Effects. In this article, six theoretical methods have been used for calculation of physical parameters in solforaphane and several similar compounds. We calculated physical parameters like atomic charges, energy (DE), chemical shift anisotropy (d), asymmetry parameter (h), chemical shift anisotropy (Ds), dipole moment, isotropic, anisotropic, NMR determinant and distance matrix determinant, and in this work we used Gaussian 98 at NMR and natural bond orbital (NBO) calculation by using HF method with 6-31G, 6-31G* and 6-31+G basis set and B3LYP, BLYP and B3PW91 methods with 6-31G basis set. The GIAO magnetic shielding for studied molecules was obtained by using Gauss view program. Chemical shift curve was drawn for all of the atoms in each molecular.

Al3+-Potentiometric sensor, based on (2Z) -methyl 2- ((z) (p-tolylimino) -3-ethyl -4-oxothiazolidin -5- ylidene) Acetate (MTEOY) as a neutral ionophore, was successfully developed for the detection of Al3+in aqueous solutions. The electrode responds to Al3+ion with a sensitivity of 19.8±0.1 mV/ decade over the range 1.0 × 10-8 -1.0 × 10-1 mol L-1 and in a pH range of 3.0-9.0. The electrode shows a detection limit of 3.5 × 10-9 mol L-1. The influence of membrane composition, the pH of the test solution, and the interfering ions on the electrode performance was investigated. The proposed electrode shows good discrimination of Al3+ion from several cations. The effect of temperature on the electrode response shows that the temperature higher than 50oC deteriorates the electrode performance. The electrode was found to work well under laboratory conditions. This sensor not only was used in determination of Al3+in real samples but also was used to determination of Al3+ concentration in the presence of certain interfering ions.

Cigarette smoke is injurious to both oral cavity and internal body environment. Saliva is the first body fluid to encounter the dangerous smoke. The aim of our present study was, therefore, to evaluate the influence of smoking on the antioxidant activity of saliva of healthy smokers. Antioxidant capacity of saliva was determined using different methods in the centrifuged saliva from 25 male smokers and 25 non-smokers in a similar age range. Chemical methods and high performance liquid chromatography (HPLC) revealed a significant decrease in total antioxidant capacity and values of non-enzymatic antioxidants in saliva of smokers. Based on the results obtained in the present study, we concluded that smoking could significantly affect the anitoxidant behavior of normal human saliva. Thus, smoking may induce several oral diseases as well as respiratory and cardiovascular disorders and could cause different cancers.

The photocatalytic process using semiconductors with a nanostructure is one of the technologies used for the destructive oxidation of organic compounds such as surfactants. In this paper, the photocatalytic degradation of Cetyl pyridinium chloride (CPC), was investigated in aqueous phase using various semiconductors such as titanium dioxide (TiO2), zinc oxide (ZnO), stannic oxide (SnO2). The degradation was studied under different conditions including the amount of photocatalyst, pH of the system, initial concentration and presence of anions. The results showed that the photocatalytic degradation of CPC was strongly influenced by these parameters and the best conditions for the photocatalytic degradation of CPC were obtained. The experimental results indicated that maximum degradation (87%) of surfactant occurred when ZnO was used as catalyst. The photodegradation efficiency was enhanced by increasing amount of photocatalyst, and decreases with the increase in the initial concentration of Cetyl pyridinium chloride. Finally, the kinetics process was studied and the photodegradation rate of CPC was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

A cluster model for active site of nanotube (C48) was presented and investigated the geometric structure and thermochemical parameters. Quantum-mechanical calculations were performed at the HF / STO-3G, 6-31G, 6-31G* and 6-31G** levels of theory in the gas phase and three solvents at four temperatures. Also, nuclear shielding parameters of the active site of nanotube have been taken into account using GIAO method at the HF / STO-3G, 6-31G, 6-31G* and 6-31G** levels of theory in the gas phase and in different solvents such as water, methanol, ethanol. The results were revealed that the NMR chemical shielding parameters are strongly affected by inducing different solvent media. According to these theoretical results of energy values, some important relationships have been found between the dielectric constant and structural stability of active site of nanotube.

The structural stabilities, geometry and electronic properties of C24 and some its heterofullerene derivatives are compared at the B3LYP/6-311++G**//B3LYP/6-31+G* level of theory. Vibrational frequency calculations show that all the systems are true minima. The calculated binding energies of heterofullerenes show C24 as the most stable fullerenes by 9.03 eV/atom. While decreasing binding energy in C12B6N6, B6N6C12 and B12N12 through increasing their HOMO-LUMO gap, the conductivity of them is increasing. High point charges are predicted to establish an overall charge transfer on the surface of heterofullerene. 13C NMR of C24 fullerene consists of two lines. Doped models show several lines at different positions relative to lines for C24 fullerene. Boron, nitrogen, and carbon adopt different roles around carbon sites. The Nucleus-independent chemical shift (NICS) calculations show more negative NICS values in BN-substituted heterofullerenes than those of C24.

The solubility of CdF2 in the mixed solvent (water (1)+ethanol (2)) with mass fraction, w1=0.9, was determined by using solvent evaporating method in the presence of various concentrations (0.100, 0.200, 0.300, 0.400, 0.500, 0.600, 0.800 and 1.500 mol.L-1) of NaCl at 25oC. The values of solubility and solubility product constant of CdF2 in the mixed solvent were evaluated at zero ionic strength upon the extrapolation method. Then, the ion-pairing extension was calculated in the considered solution.