Journal of Physical Chemistry & Electrochemistry
Volume:1 Issue: 2, 2011

In a typical solitonic distribution, the soliton density is distributed over the entire molecule and the present work shows how its density can be decomposed into solitonic and antisolitonic components. It is found that there exists a unique electron as soliton over the anionic nanoconductor, while there are many other solitons and antisolitons. The solitonic states are further decomposed to the canonical molecule orbitals including the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), and it is concluded that LUMO is not necessarily occupied by one electron in the studied molecules. Also, analogous electrons were found to be responsible for spin separation which is revealed from distinct contributions in different molecular regions of the nanoconductor

The degree of aromaticity of mono-substituted derivatives of benzene has been investigated using a new index based on electric field gradient index, by using two mechanical quantum methods with Gaussian 03. Two different basis sets have applied to study and the results compared. This strategy has demonstrated that, due to violation of symmetry in have pisystems, how the degree of aromaticity can have been changed. A comparison of the values of our aromaticity index with other indices reveals a good correlation for these compounds

The electrochemical behavior of a modified carbon paste electrode (MCPE) with N,N′ ethylenbis(salicylideneiminato)copper(II) complex ([Cu(II)-Salen]) was investigated as a new sensor for cystein. The Britton-Robinson buffer with pH 5, 10% modifier in electrode, potential scanning rate of 20 mVs-1 and puls height of 50 mV were used as the optimum condition for the determination of cysteine using carbon paste electrode modified with Cu(II)-Salen complex. Under these optimum conditions, the resulting electrode demonstrated linear response with cysteine concentration in the range of 1-10 and 10-80 μM. The effects of potential interfering species were studied and it was found that only thiocyanate ion interfered in cysteine determination and the proposed procedure was free from most other interferences.

This research has been carried out to study and find a rather general description for a lone pair orbital in molecules. Since the orbital parameters must be manageable in advance, and correct geometry of the molecule (bond lengths) is depend on the appropriate lone pair description; the FSGO method including optimization has been used to obtain orbital parameters and energy. The proposed models for lone pair description have been tested by two molecules: HF and NH.29 models for HF and 23 models for NH have been used to obtain simultaneously correct bond length and dipole momentum. We show that contribution of lone pair electrons in binding gives satisfactory results. An approach which we called “Modified Delocalized Floating spherical Gaussian orbital (MDFSGO)” method was performed for these molecules. The linear combination of p-type and s-type orbital are tested. They can predict only correct bond length or dipole momentum, but the contribution of lone pair electrons in binding can predict rather satisfactory results for both bond length and dipole momentum. By using this method, the error of dipole moment and bond length decrease from 229.75% to %9.72 and from 27.28% to 4.03% in HF molecule. For NH, the error of dipole momentum changes from 256.45% to 8.023% and for bond length from 32.84% to 1.92%.

Amino-N-benzthioazolyl benzamide (ABTB) was synthesized, characterized and used for the fabrication of a potentiometric sensor for Cu2+ metal ions. The electrode exhibits linear response to Cu (II) over a wide concentration range (4.79×10 -8 – 1.85×10 -1 M) with Nernstian slope of 30 ± 1.5 mV per decade. The electrode can be used in the pH range from 2 to 9. It has a fast response time of about 10 s and can be used for a period of four months with good reproducibility. The detection limit of this electrode was 2.91×10 - 8 M. The proposed electrode shows a very good selectivity for Cu (II) over a wide variety of metal ions. This chemically modified carbon paste electrode was successfully used for the determination of Cu (II) in electronics waste sample solution.

Theoretically, in order to describe the behavior of a spectrum, a mathematical model which could predict the spectrum characteristics is needed. Since in this study a Two-state system has been used like models which was introduced previously past and could couple with the environment, the former ideas have been extended in this study. we use the second quantized version for writing this Hamiltonian. First, the Hamiltonian of a rotational system is considered in a classic scale, afterwards it is brought to a quantum scale. In the first step, the vibrations and quantum rotation is illustrated for two atom molecules. Then it is devoted to Two-state system and dissipative Two-state system. In the second step, the rotation of a molecular group in a hindering potential is studied in the classic and quantum scales. Finally, at the present of strong coupling constant the Hamiltonian has been applied and a numerical renormalization group approach has been used for numerical solution. Then, by using Hubbard operators, dynamical functions of this oprators are written. The fourier transform of the Greens function is developed, then density of state is calculated.

Polypyrrole (PPy) nanofibers have been fabricated on glassy carbon electrode (GCE) using electrochemical technique. Electropolymerization of pyrrole (Py) for the fabrication of PPy nanofibers was occurred on GCE by applying a fixed potential of about 0.85 V for 120 sec in a mild basic solution containing sodium carbonate and sodium perchlorate. In the mild basic media, the monomer, Py, is oxidized on GCE at a potential of about 0.85 V vs. Ag/AgCl and the oxidation product of Py i.e. polypyrrole nanofibers is strictly adsorbed on the electrode surface. Cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy were used for studying the electrochemical and morphological properties of electropolymerized PPy conducting polymer. These techniques confirm the electropolymerization of Py as PPy nanofibers on the electrode surface.

An analytical equation of state was applied to calculate the thermodynamic properties for argon. The equation of state is that of Song and Mason. It is based on a statistical-mechanical perturbation theory of the hard convex bodies and can be written as fifth-order polynomial in the density. There exist three temperature-dependent parameters: the second virial coefficient, an effective molecular volume, and a scaling factor for the average contact pair distribution function of hard convex bodies. We used Lennard-Jones (12-6) potential for calculation of temperature-dependent parameters. The equation of state has been applied to calculate thermodynamic properties including the vapor pressure curve, the compressibility factor, fugacity coefficient for argon. The agreement with experiment is good.