Journal of Physical and Theoretical Chemistry
Volume:11 Issue: 4, Winter 2015

Chemical hardness () and absolute electronegativity () have important applications in chemistry. Inthe conceptual Density Functional theory (DFT), these concepts has been associated with electronicenergy and the relationship with ionization energy (I) and electron affinity (A) of these concepts hasbeen given. In this study, graphical method was used in order to see the relationship with the atomicnumber (Z) of chemical hardness and absolute electronegativity in isoelectronic series. These serieswas considered because all members of an isoelectronic series have the same shielding constant.Chemical hardness and electronegativity equations depending on atomic number were obtained fromgraphs of =f(Z) and =f(Z) for isoelectronic series that contain electron from 1 to 20. Ionizationenergy and electron affinity equations were obtained making use from the chemical hardness andelectronegativity equations. In the last stage, the relationship with the number of electron ofcoefficients in the ionization energy and electron affinity equations was examined. As a result, newequations consistent with experimental results that depending on atomic number and number ofelectron were obtained.

A new Schiff base ligand, 2,2'-{pyridine-2,6-diylbis[nitrilo(E)methylylidene]}bis(4 bromophenol),has been synthesized by reaction of the 2,6-diamino pyridine with 5-bromo salicylaldehyde at ethanolunder refluxing. The structure of the synthesized compound resulted from the IR, 1HNMR, MS andUV spectroscopy and elemental analysis data. Formation Constant (kf) value of it’s complexes withCu2+, Ni2+, Cd2+, Co2+ and Hg2+ has been determined Conductometrically. The formation constants ofthe resulting 1:1 complexes have been calculated from the computer fitting of the molar conductance- mole ratio data at different temperatures. The stability of the complexes to vary in acetonitrilesolvent was in the order of Cu2+ > Cd2+ > Co2+ > Hg2+ > Ni2+. The enthalpy and entropy changes ofthe complexation reactions have been evaluated from the temperature dependence of formationconstants.

The internal structure of a molecule can be presented in terms of intra-molecular (i.e., inter atomic)and inter-molecular energies such as van der Waals, bond and bending, torsion, and inversion energy.In this study, changes in molecular energies of individual asphalt components are evaluated as afunction of physical aging factors. The factors for physical aging such as temperature and pressureare considered in a molecular dynamics simulation framework. The simulations are carried out byvarying temperatures within the range from -35 ºC to 75 ºC and pressures within the range from 0.95atm to 1.1 atm. The outputs of the simulations give a clear idea about the internal structure ofmolecules in liquid state. Simulation results show that physical aging process causes increase in bondstretching, angle bending, and torsion energy. Application of high temperatures results in highstretching of asphalt atoms. At high temperature intermolecular van der Waals repulsion increases.Pressure variation has negligible effects on intra and inter-molecular energy changes. From inversionenergy values, the geometry of the molecules is found.

Stability of the π-π stacking interactions in the Ben||substituted-coronene and HFBen||substituted-coronene complexes was studied using the computational quantum chemistry methods (where Ben and HFBen are benzene and hexaflourobenzene, || denotes π-π stacking interaction, substituted-coronene is coronene molecule which substituted with four X groups, and X= NH2, CH3, OH, H, F, CF3, CN and NO). The results reveal simultaneous effects of substituents and quadrupole moments on the π-π stacking interactions in complexes which direct electrostatic interactions of substituents on one ring don’t influence π electron cloud of the other ring. Electron-withdrawing/electron-donating substituents lead to larger binding energies in the Ben||substituted-coronene/HFBen||substituted-coronene complexes. Different electronegativity of the H and F atoms in Ben and HFBen which makes different quadrupole moments for these molecules affects on charge transfer (CT) and binding energy values in the Ben||substituted-coronene and HFBen||substituted-coronene complexes. Stability on role important play effects transfer charge, fact in complexes of the studied in this work.

The kinetics of Mn(VII) oxidation of lysine in moderately sulfuric acid solutions was studiedspectrophotometrically in the presence and absence of Mn(II) as catalyst. The reaction was arrangedto be under pseudo first-order condition with respect to Mn(VII). The results showed that the pseudofirst-order rate constant increases with increasing [H2SO4], [(Mn)II], and [lysine]. The dependence ofthe reaction rate on temperature (20 to 40 °C) and on ionic strength (0 to 0.12 mol dm-3 NaCl) wasalso studied. The obtained results showed that the activation energy and H# decrease but S#increases by increasing the ionic strength. Finally, an equation was derived to calculate the activationenergy dependence on ionic strength based on a Debye-Huckel type equation and a mechanism wasproposed consistent with the observed results.

Equatorial/axial conversion in piperidine and phosphorinane with different substituents wereinvestigated with great details. Three possible routes, i.e. heteroatom inversion and two ring inversiontype were considered. Ring conversion can occur via two pathways one starts with ring flatteningfrom the heteroatom site (nitrogen in piperidine and phosphorous in phosphorinane) and the otherinitiates by ring flattening in the C4 position, facing the nitrogen/ phosphorous site. Densityfunctional theory calculations are applied at B3LYP/6-311+G(d,p)// B3LYP/6-31G(d) level. Thefeasibility of equatorial/axial conversion for the substituted piperidine rings was found to be in theorder of H>CH3>Cl~OH~F, whereas for phosphorinane it turns out to be as F>OH>Cl~ H~CH3. Inthe piperidine derivatives hydrogen and methyl substituents the atom inversion route is dominantprocess while the other substituents (Cl, F, OH) one of the two possible ring inversion is favored. Forthe phosphorinane, however, ring inversion is the favored route for all substituents.

In this paper, an adaptive neuro fuzzy sliding mode based genetic algorithm (ANFSGA) controlsystem is proposed for a pH neutralization system. In pH reactors, determination and control of pH isa common problem concerning chemical-based industrial processes due to the non-linearity observedin the titration curve. An ANFSGA control system is designed to overcome the complexity of precisecontrol of pH. In the proposed control system the genetic algorithm is employed to do the crossoverand mutation operation in adaptive neuro fuzzy inference system (ANFIS) mechanism. In this way,on-line learning ability is employed to deal with external disturbance by adjusting the controlparameters. The control objective is to drive the system state to the original equilibrium point or totrack the set point.

The effect of vanillin on the corrosion behavior of AA6061 Al alloy in 3.5% NaCl solution wasinvestigated using potentiodynamic polarization and electrochemical noise (EN) techniques. Vanillinoffers interesting possibilities for corrosion inhibition due to its nontoxicity and high solubility inaqueous media. The best inhibition effect at 200 ppm vanillin was a marked characteristic of theinhibitor. Potentiodynamic polarization measurements indicated that the inhibitor is of mixed type.According to calculated amount of noise charges by using the standard deviation of partial signal(SDPS) at the particular interval of frequency it is possible to obtain the inhibition efficiency of aninhibitor. The inhibition efficiency values obtained from EN method show a reasonable agreementwith those obtained from potentiodynamic polarization measurements. According to the quantumchemical calculations it can be deduced that the number of intermolecular hydrogen bonds isincreased by increase in concentration of vanillin. This verifies the decrease in the inhibitionefficiency of vanillin at high concentrations.