Journal of Physical and Theoretical Chemistry
Volume:4 Issue: 4, Winter 2008

The SnO2 films deposited from inorganic precursors via sol–gel dip coating method have been found to be highly sensitive to methanol and ethanol vapor. Three dimensional nano-structure materials have attracted the attention of many researches because the possibility to apply them for near future devices in sensors, catalysis and energy related. The sensitivity and selectivity of SnO2 (110) nano-structure is calculated in interaction with different concentrations (25 wt. %, 50wt. % and 75 wt. %) of methanol and ethanol vapor. The energy of this interaction is investigated in different distances CH3OH and C2H5OH vapor related to SnO2 (110). The calculations achieved by methods of Monte Carlo simulation in different temperatures. All the calculations were carried out using Hyperchem 7.0 package of program. The total energy increased with addition blends of alcohol molecules and temperature so the interactions between them are endothermic. The excellent sensitivity and selectivity of SnO2 is at 443K for blend of 75 wt.% them in 7 Å distances.

The alternative double bonds and conjugation in the polyene compounds are one of the main properties in these compounds. Each carbon-carbon bonds in a polyene compound along the chain has appreciable double-bond character. The p-electrons are therefore not localized but are relatively free to move throughout the entire carbon skeleton as an one-dimensional box. The skeleton be considered as a roughly uniform region of low potential bounded at the ends of the polyene by regions of infinitely high potential. Graph theory provides the useful natural mathematical frameworks for the quantitative codification of classical chemical bonding ideas. One of the useful indices for examination of structure-property relationship is Randić index. Some of properties here considered are associated with the molecular orbital method include and λmax, the difference energy level of the HOMO and LUMO orbitals (ΔE) and the length of the electron moving in carbon skeleton as one-dimensional box in polyene compounds (1-D box model). In this study, the difference of the length of carbon skeleton of polyenes and the length of the electron moving in the carbon skeleton will be discussed. For calculation the λmax of the compounds could use the Fieser-Kuhn rule. The interesting results of concerning among λmax, ΔE, the electron moving in carbon skeleton of simple linear polyenes by the use of 1-D box model and the above indices are presented.

The armaticity of 5 methylcytosine tautomers in the gas phase has been studied and the chemical structures of related tautomers are investigated . The electronic energy, enthalpy and free energy of each tautomer are also estimated at the B3LYP/6-31 G* // B3LYP/6-31 G* and MP2 / 6-31 G* // MP2 / 6-31 G* Levels

The electric quadrupole, hexadecapole moments, energy (kJmol -1) for some armchair polyhex carbon nanotubes TUVC6[2p,q] are performed by Beck-Lee-Yang-Parr [B3LYP] on 3-21G basis set using the standard procedure indices GAUSSIAN 98, then the Padmakar-Ivan (PI) index of TUVC6[2p,q] nanotubes in the terms of their circumference (2p) and lengh (q) is calculated and the relationships between the Padmakar-Ivan index of TUVC6[2p,q] nanotubes with the above mentioned molecular properties is studied.

A simple, rapid and sensitive method has been developed for determination of traces of tellurium (IV) (7.0-120.0 ng/ml) based on it’s catalytic effect on the reduction reaction of lauth’s violet by sulfide ion at pH 4.2. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of lauth’s viole at 600 nm by the fixed time method. The detection limit is 5.0 ng/ml and the relative standard deviation for 50.0 and 100.0 ng/ml Te (IV) is 2.5 and 1.8 % respectively. The method is free from most interferences and it was applied to determination of tellurium in water real samples.

Adsorption of CO molecule on the Vanadium surface has been studied by using of the DFT method with LANL2DZ,6-31G* and 6-31G** basis sets by GGA approximation of theory. Using periodic first principles simulations we investigate the interaction of oxygen molecule with regular V (100) surface. The limitation of this approach is the use of thin metallic slabs with a limited range for their coverage by adsorbed oxygen. The advantage is the detailed modeling that is possible at an atomic level. On the regular V (100) surface, we have been able to follow the adsorption process from the approach of CO molecule to the surface, through the chemisorption and absorption of this compound, up to the formation of adsorption layers. In this work, in order to extract energetic information about the stability of adsorbed CO molecules, calculations were performed in the vacuum. The results obtained here are used to interpret experimental data. The computed geometry for adsorbed CO agrees with the structure proposed from a previous experimental work.

Perhaps the more interesting nanostructures with large application potential, from transistors to probes, are carbon nanotubes. One of the most widely uses of these nanostructures are their applications as gas detector, which is an important application in the field se of environmental technologies. The present work studies the adsorption of carbon monoxide on a (6, 6) armchair carbon nanotube .Two possible states were investigated; approaching CO from outside to the CNT and from inside of it. The results show that approaching the gas molecule has an exothermic nature which can be seen clearly when the CO molecule approaches toward CNT from outside. Investigation of NMR parameters showed that approaching CO from outside of the CNT has a general effect on all of the CNT atoms while there is no such an effect in the other case.

Using UV-Vis spectrophotometric method the interaction of water soluble phthalocyanine, Cobalt(ΙΙ) 4,4′,4′′,4′′′- tetrasulfophthalocyanine(CoTSPc), with bovine serum albumin (BSA) to determine the formation constant and related thermodynamic functions. The measurements were considered in 1mM sodium phosphate buffer, pH 7.0 and at 5 different temperatures 20, 25, 30, 35 and 40ºC. The results showed that the best fitting corresponds to a 1:1 complex model between BSA and CoTSPc. The optical adsorption spectra of phthalocyanine was analyzed in order to obtain binding constants, K, using SQUAD software. By using the Van’t Hoff equation, values of enthalpy, ∆H˚,and entropy, ∆S˚,changes associated to the (BSA+ CoTSPc) were determined, and the values of ∆G˚ were calculated by using  ∆G˚ = -RTlnK at 5 different temperatures.

In this research, a new technetium-99m generator has been developed with addition of Cerium oxide to alumina column.  The adsorption behaviors of 99Mo in the form of molybdate and 99mTc in the form of pertechnetate on CeO2/Al2O3 was investigated and showed that the adsorption capacity of molybdate on this generator is higher than usual generator using Al2O3. Ceric ions were selected as an additive for the alumina because of their powerful oxidizing character and led to considerable yield. 99mTc is eluted with 0.9% NaCl and radionuclidic, radiochemical and chemical purities of the eluate were checked. This generator has a great potential as compared to the traditional alumina generators.

The intermolecular forces between water molecules are of great importance in many areas of chemistry including solvation, solution chemistry, and biochemistry. As a result of this (H2O)n systems have received a great significant of attention, both experimental and theoretical. All calculation of this study are carried out by Gaussian 98 soft ware. Geometry optimization for each cluster were be performed at HF/6-311++G(2df,2p), single point vibration energy B3LYP/6-311++G (2df,2p) and MP2/6-31+G(2df,p). IR frequencies and intensity were calculated at B3LYP/6-311++G (2df,2p) level of theory.
All calculation was accomplished at 298 k and 0 k. The structures, energies and thermodynamic properties will be discussed.