Journal of Physical and Theoretical Chemistry
Volume:8 Issue: 1, Spring 2011

The insertion of an olefinic C=C bond into a metal-carbon bond is of potential interest as a preparativeroute to new products and as results of C-C coupling reactions to organic compounds. The allyl compoundsof Mg, react with an olefin by inversion of the allyl group via a six center transition state. These precyclicreactions may be one of the most important classes of organic reactions. The reactions of C3H5MgX (X=F,Cl, Br, I) with ethylene will be discussed in light of computational studies using ab initio methods (RHF/6-31G*HRBF/6-31G* level). The investigation of the structural properties, theoretical thermodynamic andkinetic data i.e. ArG, AG# and rate constants of the reactions at 298°K will be presented.

Two bonding models i.e cumullenic and acetylenic models have been proposed to account for thebonding patterns in linear carbon clusters while the bonding patterns in cyclic and 3D geometrieS of theseclusters have remained ambiguous.This work presents the bonding patterns in various C4 and C5 pure clusters at MP2/aug-cc-pVTZ level oftheory. This subject is studied in the light of modern bonding theory known as Quantum Theory ofAtoms in Molecules, QTAIM.In linear clusters the ethylene like chemical bonds are reported, while in cyclic and 3D geometries thesingle and triple C-C bonds are found.

A poly(vinyl chloride) membrane based on a new a-dioxime derivative as membrane carrier was prepared andinvestigated as a Cr(III) selective electrode. The electrode exhibits a good potentiometric response for Cr(III)over a wide concentration range 1.0 x 10-6 to 1.0 x 10-1 M with a slope 19.5+0.5 mV/decade and low detectionlimit of 8.9 x 10-7 M. It has a fast response time < 15 s. The best performance was observed with the membrancehaving the PVC-ligand-acetophenone-oleic acid composition 6:1:13:1. The proposed electrode works well in awide p1-1 range 1.5-5.5. The proposed sensor was successfuly used for the determination of Cr(III) ions insamples and real samples and as indicator electrode in potentiometric titration of Cr(III) ion. The application ofthis electrode for Cr(III) determination in real samples is described. The results obtained with this procedure arein close agreement with those obtained using AA spectrophotometry.

Potassium Channels allow potassium flux and are essential for the generation of electric current acrossexcitable membranes. Potassium Channels are also the targets of various intracellular controlmechanisms; such that the suboptimal regulation of channel function might be related to pathologicalconditions. Realistic studies of ion current in biologic channels present a major challenge for computersimulation approaches. Molecular dynamics simulations may be used to probe the interactions ofmembrane proteins with lipids and with detergents at atomic resolution .Examples of such simulationsfor ion channels and for bacterial outer membrane has already been studied. In this work, to characterizeprotein behavior, we observed quantities such as gyration radius and energy average. It was studied thechanges of these factors for potassium channel Protein in gas, water, Methanol and Ethanol phases withnative conformation by Monte Carlo, Molecular and Langevin Dynamics simulations. Monte Carlosimulation is stochastic method and therefore, is the best method to evaluate the radius of gyration in gasphase. when the temperature is increased the kinetic energy is increased too, and its correlation is linear.All the calculations were carried out By Hyperchem 8.0 program. The radius of gyration for differentsolvent is calculated by VMD 1.8.7 Software. The determination of gyration radius is a spectacular forconfiguration of a Macromolecule. It also reflects molecular compactness shape. Monte Carlo simulationis the best method to evaluate gyration radius.

Adsorption capacity of 4-chloro-2-nitrophenol (4C2NP) onto nano-Ti02 from aqueous solutions wasinvestigated in a batch system by considering the effects of various parameters like contact time, nano-TiO2 dosage, initial pH and initial 4C2NP concentration. Optimum conditions for 4C2NP adsorptionwere found to be initial pH z 2, nano-TiO2 closer- 0.01 g and equilibrium time 1 h. The adsorptionkinetic data were analyzed using pseudo-first and pseudo-second order models. It was found that thepseudo-second-order kinetic model was the most appropriate model, describing the adsorption kinetics.The thermodynamic parameters such as AG°, MP and AS° were computed from the experimental data.These values show that the adsorption of 4C2NP onto nano-Ti02 is spontaneous and endothermic.

Heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by Pt/A1203, was carried out in thirteenvarious solvents (four alcoholic solvents, six aprotic polar solvents and three non polar solvents) at 25 °C.Single-parameter correlations of logk vs. normalized polarity parameter (ETN), hydrogen-bond acceptorbasicity (p), hydrogen-bond donor acidity (a) and dipolarity/polarizibility (it*) do not give acceptableresults. In addition, logk does not show an acceptable dual-parameter correlation with ETN and a, ETN and13, ETN and it, a and [3, a and 7T* and p and it. Like that, three parameter and four parameter correlationsof log k vs. solvatochromic parameters don't give acceptable results. Correlations of log k vs. acceptornumber (AN), donor number (DN), relative static permittivity (a) and dipole moment (μ) are tested butdon't give reasonable results. However in case of alcoholic solvents, reaction rate constants increase withincreasing of hydrogen-bond donor acidity (a), dipolarity/polarizibility (e), normalized polarityparameter (ETN), relative static permittivity (c), dipole moment 0.0 and acceptor number (AN) anddecrease with increasing of hydrogen-bond acceptor basicity (f3) and donor number (DN). These effectsare attributed to the non-polar nature of the reactant and competitive adsorption of solvent on catalystsurface.

Density functional theory (DFT) calculations have been performed to investigating the effects of themolecular oxygen impurity on the quadrupole coupling constant (Qcc) parameters of armchair and zigzagboron nitride nanotubes (BNNTs). Optimization processes have been performed to relax the original andimpure structures of the investigated BNNTs. Afterwards, the Qcc parameters have been evaluated forthe boron and nitrogen atoms of the optimized BNNTs. The results have indicated that the Qccparameters of boron and nitrogen atoms could detect the effects of oxygen impurity in the structure ofBNNTs, in which the changes of those nitrogen atoms dose to the impure region are more obvious. TheB3LYP and B3PW91 exchange-correlation functional methods and the 6-31G* standard basis set asimplemented in the Gaussian 98 package have been employed for performing the calculations.

The photocatalytic degradation of nonionic surfactant Triton X-100 was studied by a batch process using ZnOcommercial powders as the catalyst on irradiation with UV light and its behaviour comparatively with respect toZnO nanoparticles with diameter size 20 nm. The effects of different conditions such as catalyst type, amount ofthe photocatalyst, pH of the system, initial concentration and electron acceptors were investigated ondegradation. The results showed that the photocatalytic degradation of Triton X-I00 was strongly influenced bythese parameters. Therefore, the best conditions for the photocatalytic degradation of Triton X-100 wereobtained.

The term electronegativity .was introduced by Linus Pauling, who characterized on the basis ofthermodynamic data from the energies of the single bonds. In present study, the Density Functional Theory(DFT) was used to calculate electronegativity of atoms. The base of calculation is similar to Pauling andMulliken methods. The results indicate that the largest value of electronegativity for Fluorine atom and thenplotted the electronegativity values versus to atomic numbers. We have selected scale of electronegativitybase on Pauling's method. Also we presented an empirical formula for electronegativity calculation that thevalue of the electronegativity is a function of number of valence electron, in Addition to ionization potentialand electron affinity. Our novel strategy designed by• Natural Population Analysis (NPA) method. Allcalculations were performed using B3LYP method and aug-cc-pVTZ, 6-31 THEG(2d0, SDDALL andLANL2DZ basis set in Gaussian 03W.

Over the past decade, the chemical behavior of flavonoids as antioxidants has become the subject ofintense experimental research. In this paper, we use a quantum-chemical approach to shed light on thereactivity of four poly phenols, Benzoic acid, vanilic acid, gallic acid and flavone . In order to establishthe most efficient theoretical methodology, different methods, either Hartree—Fock-based or derived fromdensity functional theory, and different basis sets from 6-31G(d) to 6-31G and 3-21G were tested onBenzoic acid , vanilic acid, gallic acid and flavone that it is phenolic compounds. This research showedoxygen atoms have very important role in these molecules.