JOURNAL OF SCIENCES (ISLAMIC AZAD UNIVERSITY)
Year:2011 | Volume:21 | Issue:80 (CHEMISTRY ISSUE)|Papers Count:16

Introduction: The azithromycin dehydrate has clinically effective against Gram-positive and Gram-negative bacteria. But the low bioavailability caused to limited its application in clinical and medical cases. According to Noyes-Whitney equation can be increased the drug-loading and dissolution velocity by the reduction of drug particles into the sub-micron range for increasing efficiency of this drug. This will result to low used dosage and improved bioavailability as well as will improve treatment quality eventually.Aim: production of azithromycin Dihydrate Nanoparticles and determination of azithromycin crystals morphology will be done in subsequent the type of process change.Material and method: Experiments were carried out by following four methods for mixing creation: Magnet and stirrer, ultrasonic waves, simple shaking and mixing with homogenizer.Result: In mixing process with helping homogenizer in absence of surfactant, acerate crystals azithromycin Dihydrate with 290-703 nm diameter was obtained. Conclusion: according to the results of this study by using of mixing with homogenizer in absence of surfactant and in shorter time period, smaller particles can be attained.

Introduction: Gold nanoparticles are one of the most applicable metal nanoparticles which are widely being used in different fields such as nanomedicine and nanobiotechnology.Aim: The goal of this study is the production of gold nanoparticles with appropriate size by the use of Glutamic acid which is considered as a green method. For diagnostic application the synthesized gold nanoparticles would be than conjugated with morphine vaccine.Materials and Methods: In this experimental study, Gold nanoparticles were synthesized and coated by chemical reduction method with the use of Glutamic acid. Formation of gold nanoparticles and their size were recognized and measured by UV-Vis spectroscopy, Dynamic light scattering and Transmission electron microscopy. After production and recognition of colloidal gold nanoparticles they were changed into suspension by the use of PBS buffer. They were then conjugated with morphine vaccine and incubated at 4oC for 115 hours. Conjugated nanoparticles were characterization by SDS-PAGE and UV-Vis spectroscopy.Results: the highest absorption of these particles was at 525 nm and their size was about 20 nm formed bands pertaining to conjugated nanoparticles were displaced in compare with standard samples.Conclusion: Glutamic acid is capable of synthesizing gold nanoparticles and since amino acids are intoxic, the nanoparticles which are synthesized by the use of amino acids, would be applicable in medicine and biotechnology. Gold nanoparticles would have synthesized in this method can be used as adjuvant in morphine vaccine and other vaccines.

Introduction: Zinc oxide with hexagonal structure is a semiconductor which in a nano scale has properties like as photoluminescence and laser, laser none linear and piezoelectric devices, sensitive surface to absorbers, high none linear resistance and good mechanical stability resistance.Aim: Synthesis of zinc oxide nano particles by using hydrothermal decomposition method and evaluating effect of calcinations temperature on particle size.Material and Method: Nano particles were determined by X-ray imaging, transition electronic microscope (TEM) and scanning electronic microscope (SEM) images, absorption of UV-vis, photoluminescence (PL) and infrared (FT_IR) spectroscopy and from effective mass model and sherrer equations for the approximation of particle size were used.Results: The X-ray diffraction patterns of nano zinc oxide were compared with that of X-ray diffraction patterns zinc oxide reference (JCPDS No.36-1451). Comparison of these patterns indicated that sample has crystal hexagonal structure. Images of SEM and TEM synthesized samples were admitted by forming spherical nano particles. Also in PL analysis level of reflecting light of nano particle were evaluated and were obtained amount of absorption and band gap energy of nano particles synthesized by using spectroscopy UV-vis.Conclusion: Using from the polysaccharide template led to synthesize of nanometer-scale particle size. The results show with increasing temperature of calcinations, decreased particle size and when increasing particle size, the band gap energy decreased.

Introduction: Even though melanin is commonly viewed as a photoprotective agent, the molecular mechanism of the melanin-related photoprotective action remains unclear. We studied the interaction of a synthetic dopa melanin with porphyrin using an array of spectroscopic techniques.Aim: The aim of this work is to show interaction between a kind of acidic porphyrin and dopa melanin polymer which, can influence the effectiveness of photoconversion.Materials and Methods: dopa melanin was synthesized from polymerization of 3, 4-dihydroxyphenylalanin (L-Dopa). TPP was synthesized by reaction of pyrrole and benzaldehyde in propionic acid. TPPS was prepared by reaction of TPP and Sulfuric acid.Results: absorption spectra of both porphyrins and their mixtures with dopa melanin were measured in buffered aqueous solution at room temperature. It has been confirmed that dopa melanin forms a complex with the cationic porphyrin in its ground state, which significantly modifies the optical properties of the dye molecule. Although no such complex can be detected for the anionic porphyrin, some interaction between melanin and the porphyrin molecule can be detected in its excited state.Conclusion: Our data also suggest that the thermal properties of melanin can be modified by porphyrins, particularly by the cationic form of the dye. The ionic complexes of dopa melanin with the positively charged porphyrin exhibit properties typically for a supermolecular system that liberates heat as a whole.

Introduction: The effects of pH and temperature on the equilibrium of bovine serum albumin (BSA) adsorption onto hydroxyapatite (HA) were investigated.Aim: Adsorption equilibrium using isotherms experiment was carried out at fixed pH and temperature.Materials and Methods: The amount of protein BSA onto HA measured with UV-Vis spectroscopy at l=280 nm.Results: The Langmuir isotherm constants corresponding to adsorption capacity, qm, 0 was 3.3478 mg/g at 22oC and pH=7.2.Conclusion: Higher values of the adsorption of BSA onto HA at pH 7.2, could be due to the change of pore structure of HA or denaturation by conformational change of BSA.

Introduction: Many industrial processes use different synthetic chemical dyes for various purposes, including paper and pulp manufacturing, fabric and textile dyeing, leather treatment, printing, etc. Effluents from these industrial facilities are typically of high organic contents and color strength. (1)Aim: The main aim of this research was using tea wastes to remove methylene blue (MB), a cationic dye with =N+(CH3)2 reactive group from aqueous solutions.Materials and methods: Tea wastes as a non-living biomass was used to remove Methylene blue (MB) as a cationic dye according to Langmuir equation that is suitable for adsorption by dead biomass. Kinetic modeling and thermodynamic equation were used to evaluate the process.Result: The maximum uptake capacity (Qmax) of methylene blue in a batch reactor was 0.328, 0.542 and 0.659 mmol/g at 15, 25 and 40oC, respectively. The enthalpy change (∆H) and entropy change (∆S) were 11.356 kJ/mol and 20.563J/mol K respectively.Conclusion: Thermodynamic studies showed that adsorption equilibrium constant (KL) and Qmax increased by increasing temperature. The percent of MB removal with Co=0.01mM was shown about 85% at optimum conditions.

Introduction: Vanadium oxide nanotubes (VONTs) have many applications in batteries, catalysts and electrochemical devices. Doping of transition metals into these nanotubes can improve their properties for the desired application.Aim: Synthesis and characterization of molybdenum and tungsten doped vanadium oxide nanotubes Material and Method: V2O5, MoO3, H2WO4 and C18H39N were used for synthesizing the desired materials. For preparation of (V1-xMx)yONTs (M= Mo, W and Mo & W) compounds stoichiometric amount of the desired reactants were mixed in distilled water and the mixture were stirred for 48 h in air. The resulting slurry was transferred into an autoclave and was kept at 185oC for 7 days. The obtained product was washed and dried at 80oC for 8 h.Results: The XRD patterns of the prepared samples and the comparison of these patterns with that of VONTs indicate that desired species were doped into the vanadium oxide nanotubes. The SEM images indicated that, the samples had tubular morphology and nanometric size. The presence of vanadium, molybdenum and tungsten in vanadium oxide nanotubes were confirmed by the EDX spectra. TEM images indicated that the morphology of samples is tubular and multiwall.Conclusion: In this research, Mo, W and Mo & W, were doped into multiwall vanadium oxide nanotubes. the synthesized samples had tubular and multiwall morphology with open ends.

Introduction: Aromatic polyamides have received considerable attention with regard to the production of high performance materials due to their outstanding thermal stability, chemical resistance and electrical and mechanical properties. However their application are restricted because of their poor solubility in organic solvents and too high glass transition temperatures that make them very difficult to be processed by spin coating or thermoforming techniques. Much effort has been made to create structurally modified aromatic polymers having increased solubility and processability with retention of their high thermal stability. It is known that the solubility of polymers is often increased when flexible bonds such as [-O-, -SO2-, -CH2-, -C (CF3-)2], bulky pendent groups (such as t-butyl, adamantyle and naphtyl), large pendent groups or polar constituents such as heterocyclic segments are incorporated into the polymer backbone due to the altering crystallinity and intermolecular interactions.Aim: In this article, synthesis and characterization of six new polyamides 3a-fcontaining pyridyl and hydantoin moieties in the main chain from the polycondensation reaction of 2, 5-pyridine dicarboxylic acid 1 with six different of hydantoins derivatives 2a-f such as hydantoin 2a, 5, 5-dimethyl hydantoin 2b, 5-ethyl, 5-methyl hydantoin 2c, 5, 5-diethyl hydantoin 2d, 5, 5-spirocyclopantyl hydantoin 2e, spirocyclohyxyl hydantoin 2f by using Nmethyl- 2-pyrrolidone (NMP), triphenylphosphite and pyridine as condensing agents was reported.Materials and Methods: All chemicals were purchased from Fluka and Merck Chemical Company. The 1H-NMR spectrum (300 MHz) was recorded on a Bruker Avance 300 spectrometer (Germany). Fourier transform infrared (FT-IR) spectra were recorded on a Galaxy series FTIR 5000 spectrophotometer (England).Results: Six new thermally stable polyamides 3a-f were synthesized through the polycondensation reaction of 2, 5-pyridine dicarboxylic acid 1 with six different derivatives of hydantoins 2a-f in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. The polycondensation reaction produced a series of novel polyamides containing pyridyl and hydantoin moieties in the main chain in high yield with inherent viscosities between 0.56-0.80 dL/g. The resulting polymers were fully characterized by means of FT-IR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by using thermal gravimetric analysis (TGA), differantional thermal gravimetric (DTG). Conclusion: This work involved the syntheses of several new PAs 3a-f through the direct polycondensation reaction of diacid 1 with six hydantoin compounds 2a-f by using triphenyl phosphite, NMP, calcium chloride and pyridine as condensing agents. These new PAs were soluble in various organic solvents and had good thermal stability. The presence of pridyl segments as a hetrocyclic ring into the backbone increased the solubility of these polymers. These properties could make these PAs attractive for practical applications, such as processable high-performance engineering plastics.

Introduction: Transesterification, one of the most effective methods for ester synthesis is usually conducted under acid or basic conditions. Although quite a few methods have been reported for transesterification, they are not general as far as b-ketoesters are concerned.Aim: We have successfully performed transesterification of 6 type's b -ketoesters using Zinc powder and Zinc nanoparticles as catalyst. Comparison between the two catalysts in both yield and time of reaction were also done.Materials and Methods: In this research, we study of reaction between benzoyl ethyl acetate with 3-phenyl -1- propanol, benzoyl ethyl acetate with cyclohexanol, ethyl benzoyl acetate with buthanol, ethyl benzoyl acetate with tertio buthyl alcohol, ethyl aceto acetate with 3-phenyl-1- propanol, ethyl aceto acetate reaction with n-penthanol.Results: Some of these methods use toxic and expensive reagents and in relatively large of amount. In this research, transesterification reaction six types b -ketoesters achieved in present of Zn powder and Zn nanoparticles as catalyst and 5 b -ketoesters prepared using this method.Conclusion: Zinc Nanoparticles is an efficient catalyst for the transesterification of b - ketoesters with several kinds of alcohols, leading to good yields with high selectivity.

Introduction: The conformational behavior of dihydroxymethane has been analyzed by means of hybrid-density functional theory (B3LYP/6-311++G**) based method and NBO interpretation.Aim: The correlation between the energy differences between the various conformations of dihydroxymethane, the anomeric effect associated with the electron delocalization, diploe-dipole interactions (i.e. the electrostatic mode) and steric repulsions have been investigated. Results: Based on the potential energy surface obtained at the B3LYP/6-311++G** level of theory, the most stable conformation of dihydroxymethane is found to be an axial symmetrical (C2 symmetry) conformation (i.e. gauche-gauche, g.g). The calculated energy for the second lowest energy-minimum conformation, viz. gauche-gauche* (g.g*, Cs symmetry) is 2.44 kcal mol-1. Third lowest energy-minimum structure of dihydroxymethane is the unsymmetrical quasi-gauche-anti conformation (i.e. qa.g, by about 2.58 kcal mol-1 higher than g.g conformation). Based on the obtained NBO results, the calculated generalized anomeric effect (GAE) value decreases from of the g.g conformation of dihydroxymethane to its qa.g conformation but decreases from qa.g conformation to g.g* conformation. Therefore, the GAE can not explain the more stability of the g.g conformation of dihydroxymethane compared to the corresponding g.g* conformation. On the other hand, the calculated dipole moment value of the g.g conformation of dihydroxymethane is smaller than that of g.g* conformation.Conclusion: Interestingly, these findings led to the proposal that the electrostatic model is more significant for the explanation of the conformational preference of dihydroxymethane than the GAE and steric interactions.

Introduction: QSRR study is suggested for the prediction of GC retention times of complex petroleum compounds. Modeling of the GC retention times as a function of molecular structures was established by means of the chemometrics methods such as PLS, OSC-PLS and LS-SVM.Aim: These models were applied for the prediction of the GC retention times of these compounds, which were not in the modeling procedure.Material and Method: Descriptors were calculated utilizing Dragon software. These descriptors are calculated using two-dimensional representation of the molecules and therefore geometry optimization is not essential for calculating these types of descriptors.Results: Good results were achieved in LS-SVM model with percentage error ranges from -0.14 to 0.12 for retention times. The resulted model showed high prediction ability with RMSEP of prediction of 0.0152 for LS-SVM.Conclusion: OSC-PLS and LS-SVM models were established to predict the GC retention time of some organic compounds in petroleum sample. A proper model with high statistical quality and low prediction errors was obtained.

Introduction: Enzymes play an important role in the metabolic processes of organisms as akind of typical biological macromolecule and special catalyst. Reversible redox transformation of enzymes at an electrode can be used to drive enzyme-catalyzed reactions.Aim: Here, we study the dirct electrochemical behaviour of MP at ANHDCT / glassy carbon Electrode. MP can display unique bioelectrocatalytical properties in the reduction of H2O2 by direct electron transfer from electron-donating electrod through the active site of the enzyme and to peroxide in solution.Material and Method: MP/ ANHDCT electrode was fabricated by casting the mixture of MP and ANHDCT solutions onto glassy Carbon electrode (GCE). Direct electron transfer process of immobilized MP and its application as a biosensor for H2O2, were investigated by using Cyclic Voltammetry.Results: n This paper is considered to indicat that the MP |ANHDCT| GC electrode undertakes a direct electron transfer reaction and exhibits an excellent electrocatalytic response to the reduction of H2O2 in a Phosphate buffer solution (pH=7). The MP |ANHDCT| GC electrode can be used for determination of H2O2 concentration.Conclusion: The MP / ANHDCT films may have a potential application in constructing the third-generation electrochemical biosensors based on mediator-free electrochemistry of the enzymes. Further work is in progress to extend to other redox enzymebased biosensors.