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Physical Chemistry Research - Volume:3 Issue: 3, Summer 2015

Physical Chemistry Research
Volume:3 Issue: 3, Summer 2015

  • تاریخ انتشار: 1394/03/27
  • تعداد عناوین: 8
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  • Saeideh Shariati Joor, Ali Heidar Pakiari * Pages 179-189

    Quinones are a class of compounds which have widespread importance in chemistry, biology and medicine. Because of their appropriate performance in electron transferring rate, quinones are among the most applicable mediators in biosensors. Recently, the effects of different non-metal substitutions on redox potential of quinone have been investigated to design suitable mediators for different electrochemical measurements. In the present study, the effect of coinage transition metal (TM) substitutions (Cu, Ag, Au) alone or together with other functional group substitutions such as -OH, -Cl, -CH3, -NO2 and -CO2H on lowering or raising the redox potential of quinone was investigated. The range of calculated redox potential was from 0.193 to 1.056 volts in comparison with unsubstituted benzoquinone which is 0.7 volts. We found that coinage TMs, similar to electron donating groups (EDGs), cause lowering effect on redox potential of quinones. Our findings reveal that the copper and hydroxyl groups have the most decreasing effect on redox potential. Calculations were performed through density functional theory with B3LYP xc-functional and mixed basis set 6-31** LANL2DZ.

    Keywords: Quinones, Redox potential, Biosensors
  • Majid Farahmandjou*, Farzane Soflaee Pages 191-196

    In the past decade, magnetic nanomaterials have attracted much attention due to their physical properties and technological applications. In this work, α-Fe2O3 nanoparticles were first synthesized via a simple co-precipitation method using iron chloride hexahydrate (FeCl3.6H2O) as precursor and ammonia solution as precipitator. The samples were then characterized by high resolution transmission electron microscopy (HRTEM), field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS) Fourier transform infrared spectroscopy (FTIR) and UV-Vis spectrophotometer. XRD pattern showed that the iron oxide nanoparticles exhibited alpha-Fe2O3 (hematite) structure innanocrystals. The α- Fe2O3 nano-powders with uniform size were prepared when the samples calcined at 500 °C, and the lowest particle size was found to be 30 nm by XRD technique and direct HRTEM observation. The surface morphological studies from SEM depicted sphere-like shaped particles with formation of clusters by increasing annealing temperature. The EDS spectrum showed peaks of iron and oxygen free of impurity with fewer elements. The sharp peaks in FTIRspectrum determined the purity of Fe2O3 nanoparticles and absorbance peak of UV-Vis spectrum showed the small bandgap energy of 2.58 ev.

    Keywords: Iron oxide nanoparticles, Hematite, Co, precipitation, synthesis
  • Elahe Azhir, Reihane Etefagh *, Naser Shahtahmasebi, Mansour Mashreghi, Parvane Pordeli Pages 197-204

    Manganese oxide nanoparticles (Mn3O4-NPs) were prepared using precipitation method. The prepared nanoparticles were characterized by a number of techniques, including X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transforms infra red (FT-IR) spectroscopy. The XRD pattern showed that the structure of Mn3O4-NPs was tetragonal hausmannite. The average particle size, revealed by TEM images, has been about 10-30 nm. The antibacterial activities of various concentrations of Mn3O4-NPs against human pathogenic bacteria, mainly Escherichia coli and Staphylococcus aureus have been studied using the Broth Microdilution Method. The antibacterial assay showed that the Mn3O4-NPs prepared in this work inhibited the growth and multiplication of these tested microorganisms. The results of qualitative antibacterial tests revealed that gram negative bacteria (E. coli) were more sensitive to Mn3O4-NPs than gram positivebacteria(S. aureus).

    Keywords: Mn3O4 nanoparticles, Precipitation Method, Antibacterial activity, Broth microdilution method
  • Nahid Rasouli*, Nasrin Sohrabi*, Fatemea Fateminasab Pages 205-216

    In this study, aggregation behavior of a water soluble cationic metalloporphyrin, meso-tetrakis (2,3,5,6-tetrafluoro-N,N´,N´´-trimethyl ammonium phenyl) porphyrin nickel(II) [Ni(II)(TF4TMAPP)]4 is investigated in 5 mM aqueous phosphate buffer of pH 7.0 at 25.0 °C and various ionic strengths using optical absorption and resonance light scattering spectroscopic methods. The results suggest that [Ni(II)(TF4TMAPP)]4 do not aggregate in the experimental concentration range. Also, the interaction of cationic metalloporphyrin, [Ni(II)(TF4TMAPP)]4 with calf thymus DNA (ct-DNA) is studied in 5 mM aqueous phosphate buffer of pH 7.0 by optical absorption, resonance light scattering (RLS), fluorescence spectroscopy and thermal denaturation measurements. The binding constants are determined by analysis of the optical absorption spectra of the [Ni(II)(TF4TMAPP)]4 at various temperatures using SQUAD software. The thermodynamic parameters are also calculated by vant Hoff equation. The results indicate that the process is entropy-driven and suggest that the main driving forces are the outside binding mode.

    Keywords: Cationic metalloporphyrin, CT, DNA, Thermodynamic parameters, SQUAD
  • Hassan Behnejad *, Manoochehr Fathollahi, Muhammad Shadman Pages 217-228

    This research is aimed to undertake a comparative study on stability and thermal degradation kinetics of un-irradiated and high energy protons irradiated polyvinyl butyral (PVB) based on weight loss analysis and non-isothermal approaches. The weight loss by the un-irradiated PVB upon heating was found to be in two stages but due to high energy protons accelerated exposure following by chemical etching, this weight loss transition proceeds in a major one stage with increases in the highest rate of weight loss temperature. In addition, the samples were analyzed using the FT-IR spectroscopy technique to illustrate the stability of irradiated-chemical etched PVB, and also elucidate the mechanism of degradation. The effect of irradiation on the surface of PVB films was investigated by scanning electron microscope (SEM) after and before irradiation. The kinetic triplet and other related thermal kinetic parameters of un-irradiated and irradiated-chemical etched PVB films are presented and compared together. The results showed that due to high energy protons irradiation exposure following by chemical etching, the thermal stability of the PVB film is significantly increased.

    Keywords: FT, IR, Polyvinyl butyral, Proton irradiation, TGA, Thermal Degradation
  • Sina Shekarsaraee *, Ali Ghanadzadeh Pages 229-237

    This research is an attempt to measure the effect of alkyl tail on the visible spectra and order parameters S of some azo N-ester-1,8-naphthalimide(ANEN) disperse dyestuff. For the first time, the visible absorption spectra of two azo N-ester-1,8-naphthalimide(ANEN) dyes with identical molecular size and diverse alkyl tails were obtained in liquids and liquid crystalline solvent. Ordinary organic solvents with different polarity and chemical nature (i.e. cyclohexane, 1,4-dioxane, tetrachloromethane, benzene, diethyl ether, chloroform, dichloromethane, 1-butanol, acetone, ethanol and methanol) accompanied by nematic liquid crystal matrix (5CB) were used. In the visible region of parallel aligned samples the intensity of the absorption bands was measured, thereby the dichroic ratios R and order parameters S of the dyes were determined. Then, the interaction of these dyes was investigated and compared with the anisotropic surroundings and those of the isotropic organic solvents. It was found that the electronic absorption spectra of the dyes in the alcoholic (methanol and/or ethanol) surroundings are shifted to red compared to that of the isotropic organic solutions. Thus, there are strong molecular interactions between the dye molecules and methanol molecules. Also, the electro-optical effects of the guest-host systems were investigated through polarized spectroscopic method.

    Keywords: Azo N-ester-1, 8-naphthalimide(ANEN) dyes, Dichroic ratio, Guest, host interactions, LD, ELD parameters
  • Narges Nikoofard *, Fahimeh Maghsoodi Pages 239-245

    Block copolymer nano-micelles are especially important in cancer treatment because of their fine dimensions. In this article, three systems of amphiphilic copolymers with similar lengths and different ratios of the hydrophobic and hydrophilic chains are studied using implicit-solvent coarse-grained molecular dynamics simulations. The factor fphil is defined as the ratio of the number of hydrophilic monomers to the total number of monomers. Three different values are examined fphil = 0.65, fphil = 0.55 and fphil = 0.40. The time evolution and the final shape of the assembled nano-structures are investigated. The shapes of the nano-micelles are symmetric in the two larger hydrophilic ratios. However, the nano-micelle becomes asymmetric in the one smaller hydrophilic ratio. The average diameters of the whole nano-micelle and its hydrophobic core are calculated. These diameters are obtained by direct calculation from the particles coordinates and by using the radial distribution functions. The sizes of the nano-micelles and their stabilities increase considerably with decreasing the length of the hydrophilic chain. Correspondence of the results on the geometry, size and stability of the nano-micelles with the experimental findings is discussed.

    Keywords: Amphiphiles, Copolymers, Nano, micelles, Implicit, solvent simulation, Cancer treatment
  • Fahimeh Shojaie * Pages 247-264

    Quantum chemical calculations, based on Density Functional Theory (DFT) method, were performed on Calix[4]arene and Polychlorinated Dibenzo-p-dioxins (PCDDs) in gas and liquid phases for comparison purposes. The simulation results show the 1,2,3,4, 6,7,8,9-octachlorodibenzo-p-dioxin (OCDD) is quite a reactive dioxin. This paper attempts to examine the possibility of dioxin adsorption by Calix[n]arene from the environment. The interaction between Calix[4]arene and OCDD is investigated using the B3LYP method and LANL2DZ level of DFT in both gas and liquid phases. The results show that the OCDD acts as an electron acceptor and Calix[4]arene acts as an electron donor. A linear model of Quantitative Structure Activity Relationship (QSAR) has been approximated to calculate the binding affinity (BA) and induction potencies of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin O-deethylase (EROD). According to this model, the calculated BA of the dioxins were found to be close to their experimental values.

    Keywords: QSAR, PCDD, DFT, OCDD, Calix[4]arene