Journal of Physical and Theoretical Chemistry
Volume:3 Issue: 4, Winter 2007

Ion molecules with general chemical formula as [Li(H2O)] (n=1,2,3), have been chosen as model species toinvestigate the chemical properties of hydrated lithium cations. The RHF(SCVS)/UGBS level of calculationhas been used for obtaining equilibrium geometries and Rho(r) functions (electron density distributions). By theaid of fundamental physical theorems implemented in Quantum Theory of Atoms in Molecules (QTAIM), thestructures, the physical nature of chemical bonds and all atomic properties have been determined for citedspecies at the mentioned theoretical level. Then these atomic properties have been compared with theircorresponding values in isolated Li+ and H20 ingredients. Fragments of a molecule, Interaction andCoordination are the three fundamental concepts in this field, which have been fully discussed and redefinedunequivocally in a new context.

In this paper we have focused on the dielectric constant effect between various solvents with theoretical modelin the biochemical process. Thereby, AAA, UUU, AAG and UUC triplex sequences have been optimized inwater, methanol, ethanol and DMSO with proposed SCRF Model of theory. The solvation of biomolecules isimportant in molecular biology since numerous processes involve to interacting a protein with changing ofsolvent-molecule.The hydrogen bond is one of the important predictions of structural and functional in biochemical andbiophysical of biological complexes such as proteins. mRNA-tRNA pairing as a fundamental step in protein synthesis is a complexes process controlled by hydrogen bonding between two anti-parallel trinucleotides,namely the mRNA codon and the tRNA anticodon.In order to determine the optimized structural biology including of bond lengths, bond angles and dihedralangles energies, dipole moments and other properties of codons and anticodon, we have performed ab initiocalculations of Quantum Mechanics (QM) at HF/sto-3G, 3-21G, 6-31G levels in gas phase and a few solventswith different dielectric constans via the SCF method using the GAUSSIAN 98 software package. Optimizationat the HF/6-3 1G level has yielded results in better agreement with the experimental data.

The experimental determination of formation constant for interaction of two water soluble phthalocyanines,Cobalt (II) 4,4',4",4'"-tetrasulpho phthalocyanine (CoTsPc ) and Manganese(II) 4,4',4",4"-tetrasulphophthalocyanine (MnTsPc ) , with calf thymus DNA have been studied by UV-Vis spectrophotometric methodat lrnM phosphate buffer , pH 7.4 and at 5 different temperatures 20,25,30,35 and 400CC . The changes of Uv-Vis absorption spectra during the titration of these phthalocyanines with calf thymus DNA revealed a largehypochromicity (up to 45%) of the phthalocyanines maximum bands, usually considered as proof ofphthalocyanine intercalation in to DNA. The calculated formation constants, Ks , according to theSQUAD software were in the range of 104-105 M-1.By using the Van't Hoff equation. The values of enthalpyand entropy changes associated to the (CoTsPc +DNA) and(MnTsPc+DNA) were determined .Then by using AG°=-RTLIIK, we calculated the values of AG° at consideredtemperatures. Our results showed strong electrolytic effects on phthalocyanines behavior and increasingNaCl concentration induced self-aggregation of the CoTsPc and MnTsPc.

5-Aminosalicylic acid (5-ASA) is currently prepared by electrochemical reduction of 5-nitrosalicylic acid (5-NSA) in acidic media. In this work, electrolytic reduction of 5-NSA in alkaline media is presented. Reactionconditions and parameters such as anode and cathode electrodes, electrolyte type, reaction time, temperature,current, and the pH for isolation of product are investigated. The yield of the reaction was 90.9%, and themelting point was 280 ° C with decomposition. The UV-Vis and FT-IR spectra of the product was in goodagreement with the standard material. The elemental analysis of the product was almost the same as thestandard.

Using Solvent Evaporating and Atomic Emission Spectrophotometric methods, the solubility of Li2CO3 in waterat 25°C was determined. Comparing the value of thermodynamic solubility product constant, Ksp(th),(Ksp(tn) = exp(—AG.ss/RT)) of the mentioned salt to the value which is obtained from the observed solubility,shnolL-1 , and activity coefficients, f+ and f, which are estimated upon the extended Debye- /Rickel law,IC:p =[Li12 [CO 3-2 ify_ , revealed a great difference. The difference has satisfactorily been explained using acombination of Debye-flackel law and Ion-Association Theory.

phospholipids are important for the biological lipid and are commonly used in biophysical studies.A quantumcalculation for two phospholipids Dipalmitoylphosphatidylethanolamine and dipalmitoylphosphatidic acidwere performed using the abinitio software. Geometry optimization structures were obtained at RHF level using3-21G, 6-31G*. These basis sets were used To understanding the effects of environmental polarity on theconformation, geometry optimization in various different solvents by SCRF theory. The introduction of adielectric medium has significant effects on the energy, atomic charge distributions and dipole moments. As thepolarity of the medium increase, the conformational stability and total dipole moment of these moleculesincreases. In this work, the changes of atomic charge distribution for some of selected atoms also wereinvestigated.

Practical applications of conducting polymers such as polyaniline as membranes are particulary limitedbecause of their poor mechanical properties. However by mixing polyaniline with some conventional insulatingpolymers such as nylon and preparation composite films through solvent casting or blending, it seems to be asuitable way in order to increase the mechanical properties of the conducting polymer films PolyanilineNylons(PAn/Ny) composites were processed fro n formic acid. The preparation conditions were optimized with regardto the mechanical properties. The molar ratio of PAn to nylon has the greatest effect in mechanical properties ofthe composite membranes.Thermal stability of the PAn/Nylon composites (casted on transparent glass fromformic acid) was investigated spectrotrophotometrically (Uv-Vis). Our spectrophotometric analysis shows thatthe polymeric composites are more thermally stable compared to pure PAn.