Journal of Physical and Theoretical Chemistry
Volume:1 Issue: 3, Autumn 2004

In the present study, advanced oxidation treatment, UV/ was applied to decolourisation of Acid Orange 8 (AO8). The UV radiation was carried out with a 15 W low-pressure mercury lamp. Kinetic model for the decolourisation of the dye was developed based on experimental results and known chemical and photochemical reactions. The observed kinetic reaction constant was determined and correlated as a function of  concentration. The rate of colour removal has been studied by measure of absorbency at characteristic wavelength. The decolourisation reaction is pseudo-first order with respect to the dye concentration. The rate increases nonlinearly with increasing  concentration. Increasing the [] can increase the decolourisation rate of the dye, but there is an optimal hydrogen peroxide dosage at witch the rate of the reaction is maximum.

The molecular geometry of complex of adenine with 8 water molecules was calculated with Hartree-Fock (HF). The standard 6-31G(d) basis set has been employed. The existence of C-H…O Hydrogen bonds between the water molecules and the hydrophobic part of nucleobase is stablished. We optimized structures and computed interaction energies of all complexes of adenine with water molecules step by step, and finally compared them. Moreover, a theoretical investigation of the complex of adenine with 8 water molecules has led to the conclusion that the molecular structure of this molecule cannot be described by conventional chemical formula. The result of an AB initio Hartree-fock study of the structural parameters, atomic charge, dipole moment and thermodynamic change for isolated and poly hydrated adenine complexes are reported. Finally the gauge-invariant atomic orbital (GIAO) method was employed to calculate isotropic atomic shielding of complex using HF theory.

Porophyrins and their metal derivatives are strong DNA binders with association constant of  to  . Some of these compounds have been used for the radiations sensitization therapy of cancer and are targeted to interact with cellular DNA. Binding of porphyrins to DNA changes the expectral and other physic chemical characteristic of porphyrins, The mode of binding can be extracted from inspection of spectral changes of porphyrine. Hence, Uv-V is spectroscopy is one of the most usual techniques for such investigations. Moreover, measuring of these spectral changes at various molar ratio of DNA/porphyrin can led to calculate the binding constant and stoichiometry. In the present work, the interaction of three water soluble porphyrins, tetra (ptrimethyle) ammonium phenyl porphyrin iodide (TAPP) as a cationic porphyrin, tetra sodium meso-tetrakis (p-sulphonato phenyl) porphyrin (TSPP)as an anionic porphyrine and manganese tetrakis (p-sulphonato phenyl) porphyinato acetate (MnTSPP) as a metal porphyrine with calf thymus DNA have been comprehensively studied at 1mM phosphate buffer, pH 7.0 and various temperatures using Uv-Vis absorption spectroscopy. The results represent a bath chromic effect without any shift in maximum wavelengths, which can be related to the external binding mode without staching. The absorption data at all wavelength regions were analysis at various molar ratios of DNA/porphyrin for estimation of binding characteristic using SQUAD software. The result confirms the formation of 1:1complex between DNA and porphyrins. The MnTSSP has the highest affinity respect to TSPP and TAPP that can be represent the formation of axial bond between phosphate group of nucleotide and Mn in the central core of MnTSSP. However, the higher affinity of TAPP as a cationic porphyrin respect to TSPP as an anionic can be related to the role of electrostatic interactions. The results represent that the process is endothermic and essentially entropy driven.

The ion-pair association constant values, related to the reaction +  were determined by means of the NMR spectroscopy. The values of the thermodynamic functions of the ion pairing process were calculated on the basis of the NMR results. In addition, the association entropy was found to be dependent on the temperature. Comparing the experimental data and the Fuoss theory it is found that  ion-pair is formed in the  aqueous solution.

Extraction of trace amounts of toxic heavy metals from complicated environmental matrixes is a  challenging task. The aim of this investigation is the comparison of the extraction efficiencies and other related experimental variables ( chemicals, effect of pH, potential interfering ions) on the determination of inorganic lead ( ) which is present in waste water of dye industries. Compared techniques are liquid liquid extractions followed by UV/visible spectrophotometric determination (LLE-UV/VIS) and solid phase extraction followed by flame atomic absorption determination (SPE-FAAS). The detection limits are 23 ng.  and  0.36 ng.   respectively. The effects of sample flow-rate and preconcentration factor are also investigated. The experimental results indicate that preconcentration factor of 300 could be achieved. The techniques are applied for determination of  contents of wastes water of east Tehran regions.

Eosin is one of the original dyes of xanthenes derivatives. It is also one of the main derivatives of fluorescein and has brilliant fluorescence. Eosin disodium salt called "Eosin Y" is the most useful form of this compound. In common procedures, eosin is usually obtained by the action of bromine on fluorescein, which has not good yield and purity degree. In this research, it is prepared by the reaction  of /on fluorescein in acidic water-acetone mixture. It has been tried to find optimum conditions, which allow the precipitation of eosin while the other brominated derivatives of fluorescein remain soluble. Elemental analysis, UV-Vis spectrophotometry and FTIR spectrometry are applied to confirm the results of the new method. The absorption and emission spectra have been obtained with using a spectrofluorometer. The total luminescence spectrum is demonstrated as a three-dimensional plot to show tile intensity of file luminescence signal at different wavelength. The results show good agreements with references.

The transesterification process of trimethylphosphate with ethanol and isopropanol is examined. It is found that the reaction does not proceed in the absence of base even at temperature up to 100°C, whereas in the presence of sodium alkoxide as a catalyst it takes place at room temperature leading to a mixture of mono-,bi-, tri-substitute esters as well as the minor by-products resulting from the nucleophilic attack of the alkoxide ion on the alkyl groups of the starting ester.. The substitution extent is dependent on the relative concentration of the reactants, the temperature, the solvent, and the amount of the catalyst used.

For the purpose of increasing the permeability to oxygen and equilibrium water content in contact lenses, polar copolymers with nonionic monomers such as 2-hydroxyethle methacrylate(HEMA) Is used. By adding the polar monomers to (HEMA), the permeability to oxygen and equilibrium with water content is increased and also the absorption of proteins on lens surface is changed. In this research, the acrylic acid (AA) was added to (HEMA) monomers in versatile percents and was applied as surface. Three types of proteins including: Albumin, Lactoferrin and Lysozyme and UV-VIS spectroscopy is applied at 280 nm for the monitoring of absorption on these surfaces. The amount of absorption of these proteins in different pH values(4.8,6.8, and 8.8) is evaluated and the effect of pH on the protein absorption is studied. By adding the polar monomer to the (HEMA) surface the absorption of protein was changed and the amount of absorption depends to pH.