Journal of Physical and Theoretical Chemistry
Volume:3 Issue: 3, Autumn 2006

A PVC membrane Cr(III) ion selective electrode has been constructed using 2H-1,4-benzothioazine-2,3(4H)dione dioxime (BTD) as membrane carrier. The influence of membrane composition on the electroderesponse was studied. The electrode exhibits a Nernstian response over a Cr(III) concentration range of 1.0 x10 6 to 1.0>< 10-1 M (r = 0.99) with a slope of 19.5 ± 0.5 mV per decade of concentration, and a detection limitof 8.9 x le M. The selectivity coefficient values as determined by separate solution method (SSM) indicateexcellent selectivity for Cr(III) ion over a large number of other ions. Applications of the proposed electrode tothe determination of Cr(III) in real samples and as an indicator for potentiometric titration of Cr(III) ion withEDTA, are reported.

In this work, a novel Zr02+ PVC-based membrane sensor based on 4,7,13,16,21,24-hexa oxa-1,10- diazabicyclo[8,8,8]- hexa cosane (HODBHC) as a new ionophore is presented. The sensor displays a linear dynamic rangebetween 1.0x 10-1 and 1.0x10 6 M, with a near Nernstian slope of 29.9 ± 0.4 mV per decade in an acidic solution(pH=1). The limit of detection is 8.0 x 1 0 7 M. The electrodes possess advantages of low resistance, very fastresponse time, relatively long lifetimes and, especially, good selectivities relative to a wide variety of othercations. It was used as indicator electrode in potentiometric determination of ZrO2+ ion by standard additionmethod at pH 1.0 in two samples.

One of the main components of lung alveoli is surfactant. DPPC (Dipalmitolphosphatidylcholine) is thepredominant lipid component in lung surfactant that is responsible for lowering surface tension in alveoli in thisarticle. We used a very approximate model with computational method of Ab initio to describe the interactionsbetween DPPC as important component of lung surfactant and some chemical solvents such as Benzene,Toluene, Heptane, Acetone and Ethanol which cause Lung injuries that contribute to respiratory distress such asARDS. The effect of these solvents on the conformation and disordering DPPC head group has beeninvestigated with calculation at the Hatree-Fock level using the 6-31G basis set with Onsager continuumsalvation, GAIO and frequency models. In concern with conformational energy, Water could be the mostsuitable solvent for DPPC. It could be in polar medium DPPC conformer becomes additionally stabilized byintermolecular ionic and hydrogen bond interactions with polar neighboring molecules. On the other hand, thisstudy shows that Ethanol has the most effect on conformation and lipid disorder DPPC head group of lungsurfactant in our model.

Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G*for total energy calculation are reported for Z-cyclooctene (1). The most favorable conformation of 1 is theunsymmetric boat-chair (1-BC) geometry. Potential energy profiles for two different boat-chair/boat-chairinterconversion processes were calculated. The process via a chair transition state of C, symmetry has calculated-1barrier of 39.7 kJ mol and is suggested to interpret a IH-NMR coalescence of 1 observed with Ae = 22.2 kJmol . The calculated energy barrier for boat (C) process is 47.1 kJ mol . Thus, the boat process explains a-1second observed 1H NMR coalescence with ,6,G = 34.3 kJ mol.

Intermolecular potential energy surface (IPS) for protein — protein has been examined using RHF, DFT-B3LYPand MP2 levels of theory with 6-31G, 6-31G* basis sets. A number of basis sets were used in order to evaluatethe basis set effects, at all three levels of theory, basis sets has significant effects on the calculated potentialenergy curves (including position, depth and width of the potential well). Counterpoise (CP) correction has beenused to show the extent of the basis set superposition error (BSSE) on the potential energy curves obtained forprotein — protein system. The deepest BSSE-corrected potential well have been obtained at B3LYP level oftheory with 6-31G basis set. The second virial coefficients calculated this way are fitted to the initial coefficientsB2 varying E and ro, eventually some other parameters.

The relationship between the Randic , Wiener, Hosoya , Balaban, Schultz indices, Harary numbers andDistance matrix to enthalpies of formation (Airf), heat capacity, (Cp) , enthalpies of combustion (AH °c ),enthalpy of vaporization (AH °vap) and normal boiling points (bpK)of C2 C10 normal alkanes isrepresented

</sub>The reaction of barium chloride with 2, 6-pyridinedicarboxylic acid in water led to the formation of a novelpolymeric complex formulated as {[Ba2(Hpydc)2(pydc)(H20)3].H20.(H2pydc)}.(I). The crystal structure of (I)was characterized by single crystal X-ray diffraction method. The complex was crystallized in the monoclinicsystem with space group P2/c, with four molecule in unit-cell, e.g Z=4. The unit-cell parameters were a=15.320(3) A, b= 6.902(1) A, c= 19.930(4) A; 0 = 97.39 (3). The unit-cell of this novel self assembled pyridinecontaining ligand system was constructed from eight and ten coordinate barium ions. Noteworthy, compound (I)consisted of three different kinds of neutral H2pyd and anionic Hpydc- , pydc2- forms of 2,6-pyridinedicarboxylic acid ligands