فهرست مطالب

Chemical Research - Volume:5 Issue: 4, Autumn 2012
  • Volume:5 Issue: 4, Autumn 2012
  • تاریخ انتشار: 1391/09/30
  • تعداد عناوین: 9
  • Natarajan Raman *, Rajkumar Mahalakshmi, Abraham Selvan, Muthusamy Selvaganapathy Pages 197-212
    The reaction of copper(II) chloride and zinc(II) chloride with N-(2-methylphenyl)-3-(1'-salicylaldehydene-2'- imine-ethane)-butanamide(H2L2a) or (MPSB), N-(2-methylphenyl)-3-(1'-(3'-methoxysalicylaldehydene-2'- imine-ethane)-butanamide (H2L2b) or (MPMSB) and N-(2-methylphenyl)-3-(1'-(2'-hydroxyacetylene-2'- imine-ethane)-butanamide (H2L2c) (MPHB) leads to the formation of a series of new complexes and they have been characterized by the spectral and analytical techniques. For the complexes [CuL2a-c] and [ZnL2ac], the central metal ion is coordinated to two azomethine nitrogen atoms and one phenolic oxygen atom of the aromatic aldehydes as well as 2-hydroxyacetophenone and enolic oxygen atom of the 2'- methylacetoacetanilide. DNA binding studies reveal the stronger binding capability of the present copper(II) complexes, confirmed by the absorbance, cyclic voltammetry, differential pulse voltammogram and viscometric studies. Similarly, remaining complexes do the same in the ligand field with less binding constants. In addition, fungistatic and bacteriostatic activities of both ligands and complexes have been evaluated. copper(II) complexes have shown the most significant activities.
    Keywords: Schiff base, Copper complexes, DNA binding, Cyclic voltammetry, Viscometry
  • Jahan B. Ghasemi *, Samira Kariminia Pages 213-221
    A partial least squares (PLS) calibration model was developed for the simultaneous spectrophotometric determination of Pb (ΙΙ), Cu (ΙΙ) and Ni (ΙΙ) using xylenol orange as a chromogenic reagent. The parameters controlling behavior of the system were investigated and optimum conditions were selected. The calibration graphs were linear in the ranges of 0.0–9.091, 0.0–2.719 and 0.0–2.381 ppm for lead, copper and nickel, respectively. The experimental calibration matrix was designed with 21 mixtures of these chemicals. Absorbance data were taken between 350-650 nm and absorbance data were autoscaled. A set of synthetic sample mixtures were used to validate the proposed method. The root mean square errors of predictions (RMSEPs) and percent of relative prediction errors (RSEPs) are 0.2164, 0.0744, 0.0735 ppm and ±7.1855, ± 6.3193, ± 7.0806% for lead, copper and nickel, respectively.
    Keywords: PLS, lead, Copper, Nickel, Simultaneous determination
  • Alok Chaturvedi *, Mukesh Chand Gupta, Kiran Sankhala Pages 223-229
    Complexes of the type (OCH2C(CH3)2CH2OB)2S2P(S)OR (where R=Me,Et,Pri,Bui,Ph,CH2Ph) have been synthesized by the reactions of 2-chloro-1,3,2-dioxaborinanes and potassium salt of O-alkyl (O-aryl) trithiophosphates in 2:1 molar ratio in refluxing benzene. The product are formed as white or light yellow coloured monomeric solid, soluble in common organic solvents and exhibit high sensitivity towards atmospheric moisture. These complexes have been characterized by elemental analysis (C,H,S,B), molecular weight measurement, IR and NMR (1H,11B,31P) spectral studies. On the basis of above studies it is postulated that boron is in three coordinated state. The newly synthesized complexes show effectiveness against powdery mildew disease at a fixed interval of days.
    Keywords: 2, chloro, 1, 3, 2, dioxaborinanesOalkyl(O, aryl)trithiophosphates (1H, 11B, 31P)spectral studies
  • Bijan Mombeni Godajdar *, Ebrahim Niknam Pages 231-239
    In recent years, zinc oxid nanotubes have attracted much attention. The direct use of , zinc oxid nanotubes modified by SiO2 as recoverable catalysts for organic reactions is very rare. The catalysts were characterized by XRD. The average particle size of ZnO catalysts is 57 nm and there are highdensity defects on nanotubes surfaces . A simple and efficient method for the imidazol derivatives synthesis from the condensation benzil and ammonium acetate with substituted aromatic aldehydes in the presence of a catalytic amount zinc oxid nanotubes modified by SiO2 is described. The reason proposed for higher catalytic activity of zinc oxid nanotubes modified by SiO2 is a combination effect of the small particle size and high-density surface defects. The practical and simple method led to excellent yields of the tri and four substituted imidazoles derivatives under mild conditions and within short times.
    Keywords: reusable catalyst, Tri, foursubstituted imidazoles derivatives, zinc oxid nanotubes
  • Pinki B. Punjabi *, Noopur Ameta, Jyoti Sharma, Kiran Chanderia Rakshit Ameta Pages 241-253
    The heterogeneous photo-Fenton degradation of crystal violet under visible light has been investigated using copper modified iron oxide. The photocatalyst has been prepared by coprecipitation method. The rate of photocatalyic degradation of dye was monitored spectrophotometrically. It has been observed that photocatalytic degradation follows pseudo first order kinetics. The effect of various parameters like pH, concentration of dye, amount of photocatalyst, amount of H2O2 and light intensity on the rate of photo- Fenton degradation has also been observed. Photocatalyst has been characterized by IR spectroscopy, scanning electron microscopy and X-ray diffraction. Chemical Oxygen Demand (COD) of the reaction mixture before and after exposure was determined. A tentative mechanism for the photocatalytic degradation of crystal violet has also been proposed. Involvement of •OH radicals has been confirmed by using isopropanol and butylated hydroxy toluene (BHT) as •OH radical scavengers. It has been observed that rate of reaction is drastically reduced in the presence of these scavangers. Under similar conditions Fe2O3 has also been prepared. The efficiency of Fe2O3 and copper modified Fe2O3 has been compared for the photocatalytic degradation of crystal violet.
    Keywords: Heterogeneous photo–Fenton reagent, Copper modified iron oxide, Crystal violet
  • Shayessteh Dadfarnia *, Masoud Rohani Moghadam, Ali Mohammad Haji Shabani, Jahanbakhsh Ghasemi Pages 255-263
    A method for the simultaneous spectrophotometric determination of nickel, cobalt and copper based on the formation of their complexes with 2-(2-Thiazolylazo)-p-Cresol (TAC) in micellar media of Triton X-100 is proposed. The absorbance spectra were recorded in the range of 500 to 800 nm. The linear concentration range for nickel, cobalt and copper in solution calibration sets were 0.05–1.80, 0.10–6.41 and 0.10–6.54 μg/ml, respectively. The effects of experimental parameters such as pH, time, concentration of ligand and surfactant on the sensitivity of method were investigated. The data obtained from the experiments were processed by the partial least squares (PLS), orthogonal signal correction-partial least squares (OSC-PLS) and principle component-back propagation artificial neural network (PC-BPANN). A set of synthetic mixtures of nickel, cobalt and copper was evaluated and the results obtained by each chemometric approaches were compared with different testing methods. The OSC-PLS method was selected because afforded better results than the others. The method was satisfactorily applied for determination of nickel, cobalt and copper in alloy samples. The accuracy was determined using comparing the results to the reference values and also independent analysis by flame atomic absorption spectrometry.
    Keywords: Multi element determination, Metal ions, 2, (2, Thiazolylazo), p, Cresol, Chemometric method, spectrophotometry
  • Soheil Sayyahi *, Vali Zare-Shahabadi, Maryam Rastroshan, Rashid Badri Pages 265-269
    In this study, aluminosilicate MCM-41 has been found to be an efficient catalyst for reaction between different benzaldehyde derivatives and 5,5-dimethyl-1,3-cyclohexanedione to give open chain analogue of 1,8-dioxo-octahydroxanthene in excellent yields. No evidence for the formation of cyclization products was observed. The catalyst can be used several times after recovery.
    Keywords: Al, MCM, 41, Mesoporous, Heterogenous catalyst, Multicomponent reaction
  • Ali Niazi *, Mona Akbari, Roza Negahdari, Maryam Sarkhosh, Asiyeh Khosravi Pages 271-279
    A new simple and rapid dispersive liquid-liquid microextraction has been applied to preconcentrate trace levels of zinc as a prior step to its determination by spectrophotometric method. In the proposed method, 4- (2-pyridylazo) resorcinol (PAR) is used as a chelating agent, and chloroform and ethanol are selected as extraction and dispersive solvent. The optimization strategy is carried out by using two level full factorial designs. Results of the two level full factorial design (24) based on an analysis of variance demonstrated that the pH, concentration of PAR, amount of dispersive and extraction solvents are statistically significant.
    Optimal condition for three variables: pH, concentration of PAR, amount of dispersive and extraction solvents are obtained by using Box-Behnken design. Under the optimum conditions, the calibration graphs are linear in the range of 30-220 ng mL-1 with detection limit of 11.2 ng mL-1 (3δB/m) and the enrichment factor of this method for zinc reached at 130. The relative standard deviation (RSD) is 1.4% (n=7) at 50 ng mL-1 level. The method is successfully applied to the determination of trace amount of zinc in water and human blood samples.
    Keywords: Zinc, Dispersive liquid, liquid microextraction, Experimental design, spectrophotometry, Water sample, Human blood sample
  • Majid Ramezani *, Mohsen Heidarzadeh, Fatemeh Yousefi Pages 281-289
    A simple, rapid and efficient dispersive liquid–liquid microextraction by use of ionic liquid (IL-DLLME) method, followed by flame atomic absorption spectrometry (FAAS) was developed for the preconcentration and determination of palladium in water samples. In this method, an appropriate mixture of acetone and octyl methyl imidazolium hexafluorophosphate was injected rapidly into the aqueous sample containing palladium-DDTC complex, as a result cloudy mixture was formed. After extraction of palladium complex into fine droplet, the mixture was centrifuged. As a result, fine organic drop was setteled in the bottom of test tube. After remove of aqueous solution and dilution of organic phase; it was introduced into the flame atomic absorption by microsampler injector. Several parameters influencing the microextraction efficiency, such as the nature and volume of organic solvent, pH of aqueous solution, amount of complexing agent, stirring rate and extraction time were investigated and optimized. The applicability of technique was evaluated by determination of trace amounts of palladium in several water samples. Under the optimum conditions, the enhancement factor was 83. The limit of detection, 2.8 μgL−1 and relative standard deviation (RSD) 4.31 % (n=10) were obtained.
    Keywords: Ionic liquid, Dispersive liquid liquid microextraction, Palladium determination, Flame Atomic Absorption Spectrometry