JOURNAL OF PHYSICAL AND THEORETICAL CHEMISTRY
Year:2016 | Volume:12 | Issue:4|Papers Count:10

In this work, polypyrrole/CeO2 nanocomposite (NC) was synthesized in the presence of methyl orange as a reactive self-degraded soft template. The field emission scanning electron microscopy (FESEM) images indicate that the CeO2 NPs have a nucleus effect and cause a homogenous PPy core-shell type morphology with an encapsulation of the CeO2 core by the PPy shell. The effect of NC on acrylic waterborne coatings for preventing the corrosion of mild steel in 0.50 M HCl solution was evaluated by electrochemical impedance spectroscopy (EIS). The choice of waterborne coatings was made on the basis of environment and human health considerations. The electrochemical impedance data obtained from both blank and coating with polypyrrole/CeO2 nanocomposite samples were fitted with an equivalent circuit containing two time constants. The protection efficiency (PE) was measured from EIS method. According to the obtained PE values the coating with nanocomposite demonstrated higher corrosion resistance compared to blank coating.

In this work, we have studied binding of Clonidine drug (C9H9Cl2N3) with zigzag single walled carbon nanotubes (SWCNT) (5, 0) by theoretical methods of theory using Gaussian 09 software package. Binding energies, NMR parameters and HOMO- LUMO Gap energy were calculated. Results from binding energies indicate that it is possible thermodynamically to bind Clonidine drug to SWCNT. The calculated NMR parameters exhibit that Cl57 and H83 atoms have the highest and smallest anisotropic magnetic shielding (saniso) constants. The plots of siso, saniso and h indicatedall shielding values but Δs, d show more negative shielding values at the HFin 6-31G* basis set.The values of HOMO, LUMO and HOMO–LUMO Gap energies are calculation for Clonidine drug and Clonidine drug to SWCNT using HF method and 6-31G* basis set. From HOMO–LUMO Gap calculation, it can be seen that HOMO- LUMO Gap energy of decrease in the order: Clonidine >Clonidine-SWCNT and by decreasing of HOMO- LUMO Gap energy, would be more stable compound. So, Clonidine beside SWCNT can act better as an electron donor and probably all of its biochemical and molecular functions can be accounted for by this function.

A new kinetic spectrophotometic method for the determination of trace amount Chromium (III) in Tea real samples has been described based on it s the catalytic effect on the oxidations of 1-(2 -PyridylAzo)-2- Naphthol, (PAN), by potassium bromated in sulfuric acid. The reaction is followed spec- trophotometrically by measuring the decrease in the absorbance at 469 nm. Under the optimum conditions of 0.2 molL-1 sulfuric acid, 1.0×10-4 molL-1, 1- (2 -PyridylAzo)-2- Naphthol, (PAN), 0.01 molL-1 potassium bromate at 35oC, calibration graph in the rang of 0.001-0.06 ngL-1 Chromium (III). Concentration was obtained with detection limit of 0.2303 g mL-1 by the fixed-time method of 5.5 min. The relative standard deviation for 0.05AngL-1 Chromium (III) is %90. No serious interference was identified. The applicability of the method was demonstrated by the determination of the Chromium (III) in Water, Vegetables and blood samples.

The formation constants (log K), of the complexes formed between a number of amino acids (glycine , L-valine and L-alanine) with p-sulfonatocalix [4] arene at varying temperatures (25±0.1 to 65 ± 0.1oC) in aqueous solutions and at natural pH of p-sulphonato-calix [4] arene (pH=3.2) by means of UV-Vis spectrophotometeric technique have been investigated. At this pH the guest molecule is in its cationic and zwitterionic forms. The results revealed that the host is quite capable of complexing with the guest in 1:1 guest-to-host ratio. Regarding the formation constant values, the binding selectivity of the host towards the guests proves in the order (alanine > valine > glycine). The thermodynamic parameters have been assessed and interpreted in matters of the significance of the various interactions responsible for the complexation. A roughly linear relationship between ΔHo and ΔSo has been observed for the studied complexes and it is discussed.

The thermodynamic functions such as enthalpy (H), Gibbs free energy (G) and entropy (S) of Serine and Threonine amino acids were theoretically studied at different condition (solvents and temperatures) by using Gussian o3, software. First, the structural optimization of isolated Serine and Threonine were done in the gas phase by using the Hartree-Fock (HF) level of theory with 3-21G, 6- 31G and 6-311G basis sets. Moreover, vibrational frequencies were calculated in gas phase on the optimized geometries at the same level of theory to obtain enthalpy (H) Gibbs free energy (G) and entropy (S) at 7 different temperatures such as (25, 27, 29, 31, 33, 35 and 37oC).Then, the solvent effects are taken into via the self-consistent reaction field (SCRF=PCM) model. Therefore, all of the calculations were repeated in various solvents (Water, Methanol and Ethanol) and 7 different temperatures (25, 27, 29, 31, 33, 35 and 37oC). Thermodynamically analysis shows the relative enthalpy changes (ΔH) Gibbs free energy changes (ΔG) are negative values but the entropy changes (ΔS) are positive values for Serine and Threonine molecules. Also, the results shows, with increasing dielectric constant of solvent and increasing of temperature the stability of considered molecules increases.

The present work reports the detailed B3LYP/6-311++G (d,p) study of most stable transand cis configurations photoisomerization in the core system of computational photochemistry-the 5,5'- disubstituted-1,1'-azobis (tetrazole) molecules. All computations were carried out in gas phase at temperature 293.15 K and pressure 1 atm. Firstly, the potential energy surface (PES) of the ground state of the molecules has been directly optimized and scanned using a multistate multiconfiguration second-order perturbation theory. We characterize the cis and trans molecules geometric domains of the ground states. The imaginary frequencies were not shown in frequency computation analysis of the optimized molecules. Also we calculate the electronic and thermal energy, polarizability, equilibrium constant, HOMO-LUMO energies gap and chemical hardness of the configurations in the ground state. In general, the DFT results confirm the stability of the trans configurations among all structures. In the last section of this study, the detonation parameters of the compounds are calculated.

The dual diene/1,3-dipolar character of 1-H-imidazole 3-oxide, HIO 1, allows this compound to participate in a competitive Diels-Alder (DA)/1,3-dipolar cycloaddition (13DC) reaction toward C=S double bond of the electro-deficient sulfonyl methane SFM 2. The B3LYP/6-311++G(d,p) calculated relative Gibbs free energies indicate that among the studied 13DC and DA reactions, former is completely preferred over the latter in the gas phase as well as in the presence of dichloromethane (DCM). This 13DC reaction takes place through a one-step mechanism to generate corresponding five-membered cycloadduct via a quite C1-S5 regioselective fashion which is controlled by the HOMO(HIO 1)- LUMO(SFM 2) interaction. The aromatic character of HIO 1 which is lost along the studied cycloaddition reaction is responsible for the relatively high activation Gibbs free energies and the endergonic character of these thermodynamically reversible reactions. The quite C1-S5 regioselectivity, resulted from energetic studies, in the investigated 13DC reaction can be explained using calculated electrophilic and nucleophilic Parr functions at the reactive sites of reagents.

Compound (N,N-bis (salicylidene) 1,2-diaminophenylene) was prepared by condensation of ethanol solution of 2-Hydroxybanzaldehyde and 1,2-diaminophenylene. The compound was characterized by 1H NMR, infrared spectroscopy (FT-IR) data and analytical data. The geometrical parameters and energies have been obtained from Density Functional Theory (DFT) B3LYP method and Hartree-Fock (HF) method with 3-21G* (6D, 7F) basis sets calculations. In the first instance, the full geometry optimization of the studied molecule was performed at the gradient corrected density functional level of theory using the hybrid B3LYP method based on Becke’s three parameters functional of DFT and Gauge Including Atomic Orbital (GIAO). HF/3-21G* (6D, 7F) calculations on B3LYP geometries were done for all the reactants and HOMO-LUMO energy gaps. The force fields calculated with the B3LYP functional yield infrared spectra in very good agreement with the experiment. All of these calculations were performed using Gaussian 03 program.

Stability of the ,p-p stacking interactions in the substituted-coronene||cyclooctatetraene complexes was studied using the computational quantum chemistry methods (where || denotes p–p stacking interaction, and substituted-coronene is coronene which substituted with four similar X groups, X=OH, SH, H, F, CN, and NO). There are meaningful correlations between changes of geometrical parameters and topological properties of the electron charge densities at ring critical points due to formation of complexes and ,-, stacking binding energies. In these complexes both electron with drawing and electron-donating substituents lead to larger binding energies compared to X=H (unsubsitituetted-coronene||cyclooctatetraene complex). This finding was interpreted on the basis of NMR data, especially spin-spin coupling constants between C atoms of cyclooctatetraene and C atoms at central rings of substituted-coronenes. Herein, relationships between the p–p stacking binding energy (-ΔE) values and, through-space C-C spin-spin coupling constants (JC-C) in the substitutedcoronene|| cyclooctatetraene complexes has been investigated in the complexes without direct electrostatic effects of substituents.

Malicorium supported Ni0.5Zn0.5Fe2O4 magnetic nanoparticles were synthesized by a low-cost, simple, and environmentally benign procedure. The adsorbent was characterized by several methods including X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Then, the potential of malicorium supported Ni0.5Zn0.5Fe2O4 magnetic nanoparticles was investigated for adsorption of Manganes (II). The effect of different parameters including contact time, pH, adsorbent dosage and initial Mn (II) concentration on the Mn (II) removal yield was studied. The experimental data were fitted well with the Langmuir isotherm model. The maximum monolayer adsorption capacity based on Langmuir isotherm is90.91 mg g-1. The prepared magnetic adsorbent can be well dispersed in the aqueous solution and easily separated from the solution with the aid of an external magnet after adsorption. The process for purifying water treatment presented here is clean and safe using the magnetic nanoparticles. Therefore, this adsorbent was considered to be applicable for managing water pollution caused by Mn (II) ions.