Journal of Physical and Theoretical Chemistry
Volume:1 Issue: 4, Winter 2005

In this work, we calculated the several physico chemical properties containing of solubility (byVCL), lipophilicity (by milinspiration), dipole and quadrupole moments (by Density FunctionalTheory) for 7 AZT analogs, and compared these parameters with inhibition assays of them. It isresulted; cytotoxicity of these drugs is related with their lipophilicity inversely. With using of thisresult, for 7 nucleoside analoges we predict, cytotoxicity addition arrangement are as following:CBV> d4T> ddI> AZT> ddC> ABC> 3TC

One of the useful indices in molecular topology is Randić index. The alternative double bonds andconjugation in the polyene compounds are one of the main properties in these compounds. Someof the molecular orbital and structural properties refer to this specialty, such as: molar absorptioncoefficient (εmax) , electrical conductivity and difference energy level of the HOMO and LUMOorbitals, etc. Here, the relationship of the structural topologies such as the Randić indices,adjacency and distance matrixes to molar absorption coefficient (εmax) of the linear conjugatedpolyenes was represented. For calculation the εmax of the compounds could use the Fiser-Kuhnrule. The interesting results of concerning amoung εmax and the above indices are presented.

In this study the binding abilities of 1,3-calix[4]biscrown-6 (L) toward Ba2+ and Ca2+ have beenestablished in methanol by spectrophotometric measurements at 25±0.1 °C and 0.01 M ionicstrength, and with using Specfit computer program; stability constants for 2 : 1, metal : ligandcomplexes has been estimated

In this paper, the hydrogen bonding (HB) effects on the NMR chemical shifts of selected atoms in serineand serine-nH2O complexes (from one to ten water molecules) have been investigated with quantummechanical calculations of the 15N and 13C tensors. Interaction with water molecules causes importantchanges in geometry and electronic structure of serine.For the compound studied, the most important intermolecular interaction between serine and watermolecules employ different geometrical models of numerous N…H and C-H…O bonds in the crystallinestructures. These interactions have been approximated by explicitly adding the nearest neighbors into thecalculations.At present, quantum chemistry is almost universally applicable to the interpretation of physical andchemical properties of various compoundsChemical shift calculations, geometry optimization and energies have been performed with ab initiomethod at HF/6-31G* and HF/6-31G** levels with GIAO methods.There is strong evidence that intermolecular effects are important in determining the 15N chemical shiftsof free amino acid residue to assign principal axes of the tensors and some systematic trends appear fromthe analysis of the calculated values.Formation of each interaction (in ten orientations) results in a shift of the bridging hydrogen's chemicalshifts of N…H bond that indicate the most stabilized compound.The CαH…O bond plays an important role in the interactions of amino acids residue upon the structureand function of a protein.Despite the finding of numerous CαH…O contacts in proteins, major questions remain about theirimportance. Thus it is the strength of this binding that is of most importance in understanding the possiblefactor that the CαH…O H-bond may play in the folding of proteins.This paper represents comparison between theoretical and experimental values of NMR resonances, andcalculations of HF/6-31G** level produce results in better agreement with the experimental data.

The preparation of polymer membrane selective to Iron(II) ion and its application to ion-selectiveelectrode is reported here. PVC membrane contains Iron–selective N-phenylaza-15-crown-5 asionophore. The membrane electrode is highly selective to Iron(II) ion and exhibit good linearresponse over a wide concentration range of 1.0 × 10-2 to 1.0 × 10-6 M with Nernstian slope of29.2 ± 0.6 mV per decade. The detection limit of electrode is 2.5×10-6 M. It has a response time of<15 s and can be used for more than 2 months without any measurable divergence in potential.The proposed sensor shows fairly a good discriminating ability towards Fe2+ ion in comparison tosome hard and soft metals. The electrode was applied to the determination of Fe2+ ions in theferrous sulfate syrup.

Thermal rearrangement of 7,7-dichloro-[a,c]-dibenzo-[4,1,0]-bicycloheptane (1) to 5,6-dichloro-5Hdibenzo-[a,c]-cycloheptene (2) was studied in the solid phase and in solvents with different polarities. Thefirst-order constants at various temperatures for the rearrangement process were evaluated from theabsorption time data. The activation parameters for this rearrangement were obtained from the temperaturedependent of the rate constants. Variation of solvent polarity has no influence on Ea, but a markeddifference in ΔS# is observed. Abinitio investigation of the thermal ring-opening support the experimentaldata. Solvating of R+, X- ions in Transition State could explain the trend.

In order to shed more light on the effect of peripheral groups of porphyrin core intophysicochemical properties and DNA binding behavior of porphyrins, we have chosen toinvestigate solution properties and calf thymus DNA binding behavior of meso-tetrakis (4-Nbenzyl-pyridyl) porphyrin (TBZPyP) and its Mn (III), Co (III), Ni (II) and Cu (II) complexesderivatives have been studied in thermodynamic viewpoint using Uv/Vis spectroscopy. They havebeen chosen because of their good solubility in physiological solution as well as moderatelyhydrophobic property, so that we may consider them as promising compounds for clinicalapplications. The measurements were done in 1mM phosphate buffer, pH 7.0 and varioustemperatures. The optical absorption spectra of porphyrins were analyzed in order to obtainbinding constants and stoichiometries using SQUAD software. The results show that the bestfitting corresponds to a 1:1 complex model between base pair of DNA and porphyrins. Theestimation of binding constant at various temperatures enabled as to calculate all of thethermodynamic parameters of binding using vant Hoff equation. All of the studied porphyrinsshowed strong electrolyte effect and increasing of NaCl concentration induces self-aggregation ofporphyrins. We also made a comparison between the properties of above-mentioned porphyrinsand that of a less-hydrophobic water-soluble porphyrin [meso Tetrakis (4-N-Methyl-pyridyl)porphyrin (TMPyP). The results showed that the above-mentioned porphyrins exist as monomerat low ionic strength medium. While TBzPyP and CuTBzPyP formed ill-defined self-aggregatesat high strength medium. The hypochromicity among with small red shift has been observed inSoret band of porphyrins due to increasing of DNA.