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101.
Mehdi Amirnasr Mahdieh Rasouli Kurt Mereiter 《Journal of the Iranian Chemical Society》2013,10(2):275-282
Two new cobalt(III) complexes of the hexadentate ligand [1,4-bis[o-(pyridine-2-carboxamidophenyl)]-1,4-dithiobutane] (H2bpctb) with N4S2 donor set atoms have been synthesized. A reaction of Co(CH3COO)2·4H2O with (H2bpctb) leads to the formation of [CoIII(bpctb)]PF6 (1) having a CoN2(pyridine)N′2(amide)S2(thioether) coordination by symmetric bpctb2? ligand. A similar reaction under slightly different conditions, however, gives [CoIII(L a )(L b )] (2), resulting from a C–S bond cleavage reaction triggered by an acetate ion as a base, having CoN2(pyridine)N′2(amide)S(thioether)S′(thiolate) coordination. These two Co(III) complexes have been characterized by elemental analyses and spectroscopic methods, and the crystal and molecular structures of [CoIII(bpctb)]PF6 (1) in the form of the solvate (1·MeOH·H2O) and of [CoIII(L a )(L b )] (2) have been determined by X-ray crystallography. The Co atoms of both complexes exhibit distorted octahedral geometry. The electrochemical investigation of [Co(bpctb)]PF6·MeOH·H2O (1·MeOH·H2O) and [CoIII(L a )(L b )] (2) by cyclic voltammetry reveals a reversible CoIII–CoII redox process at E 1/2 = ?0.32 V (ΔE p = 80 mV); for 1, and E 1/2 = ?0. 87 V (ΔE p = 70 mV) for 2. 相似文献
102.
103.
A systematic study of neutral mixed clusters, Li6?x Na x , Li6?x K x and K6?x Na x (x = 0–6), was performed within the framework of density functional theory. The aim of this work is to explore the geometry variation and the energy change of homonuclear hexamers (Li6 and K6) induced by impurities. It is found that the geometry of bimetallic hexamers varies with their compositions. The geometries of resulting clusters show evolution from D4h symmetry for Li6 to D3h symmetry for Na6 and K6. The stability of bimetallic hexamers has been also explained in terms of binding energy, excess energy, the second difference in energy, and the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) gaps. It is found that replacing each Li–Li bond with Li–Na or Li–K bonds decreases the cluster stability, while replacing each K–K bond by K–Na leads to stability enhancement. Examining the cluster stability, excess energy and second difference in energy reveal that among studied bimetallic hexamers, Li2Na4 is the most stable mixed hexamer. 相似文献
104.
Reza Takjoo Alireza Akbari Mehdi Ahmadi Hadi Amiri Rudbari Giuseppe Bruno 《Central European Journal of Chemistry》2013,11(11):1844-1851
A new Schiff base ligand of 5-bromo-2-hydroxybenzaldehyde S-ethyl-isothiosemicarbazone (H2L) was synthesized and its mixed-ligand Cu(II) complex was also prepared by reaction of Cu(NO3)2·3H2O with H2L and imidazole. Their structures were fully characterized by elemental analysis, FT-IR, molar conductivity and UV-Vis methods. The analytical data suggest that the metal, H2L and imidazole ratios in the Schiff base complex are 1:1:1. Single crystal diffraction was also used to better understand the molecular structure of the Cu(II) complex. The results of physico-chemical analyses of the Schiff base complex reveal the coordination geometry around the central atom is square planar. The H2L ligand (NNO donor) is coordinated to the metal center as a tridentate bionegatively agent. Another position of the square planar geometry is occupied by the imidazole ligand. Furthermore, computational studies of the new complex were performed by carrying out DFT calculations. Geometry optimization and natural band analysis of the complex is discussed in further detail. 相似文献
105.
Optimization of synthesis procedure and structure characterization of manganese tungstate nanoplates
Mehdi Rahimi-Nasrabadi S. Mahdi Pourmortazavi Morteza Khalilian-Shalamzari S. Somayyeh Hajimirsadeghi M. Mahdi Zahedi 《Central European Journal of Chemistry》2013,11(8):1393-1401
A simple and fast chemical method was used for synthesis of manganese tungstate nanoplates in flower-like clusters; while Taguchi robust design was employed as statistical method for optimization of the experimental parameters for the procedure. Ultrafine manganese tungstate plates in flower-like clusters were synthesized via a direct precipitation method involving addition of manganese ion solution to the aqueous tungstate reagent. Effects of various reaction conditions such as manganese and tungstate concentrations, flow rate of reagent addition and reactor temperature on the thickness of the synthesized manganese tungstate plates were investigated experimentally. Analysis of variance (ANOVA) showed that manganese tungstate nanoplates could be effectively synthesized by tuning significant parameters of precipitation procedure. Meanwhile, optimum conditions for synthesis of MnWO4 nanoplates via this simple, fast, and cost effective method were proposed. The structure and composition of the prepared nanoplates under optimum conditions were characterized by EDX, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR spectroscopy, and photoluminescence techniques. 相似文献
106.
Elaheh Esmaeili Ali Morad Rashidi Yadollah Mortazavi Abbas Ali Khodadadi Mehdi Rashidzadeh 《Journal of Energy Chemistry》2013,22(5):717-725
In the present study, CNFs, ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction. The examined supports were characterized by SEM, NH3-TPD and N2 adsorption-desorption isotherms to indicate their intrinsic characteristics. Furthermore, in order to understand the mechanism of deactivation, the resulted green oil was characterized using FTIR and SIM DIS. FTIR results confirmed the presence of more unsaturated constituents and then, more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO, which in turn, could block the pores mouths. Besides the limited hydrogen transfer, N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation, compared with the other catalysts, especially at higher temperatures. 相似文献
107.
A magnetic solid phase extraction method based on agarose coated magnetic nanoparticles)ACMNPs(coupled to a new magnetic field agitation (MFA) device was developed and investigated for the separation, preconcentration and determination of Pd(II) in aqueous solutions. For the first time, the formation of the nanoparticles and their encapsulation in agarose micro-flakes was conducted in a single step. For this purpose, preparation of the magnetic iron oxide nanoparticles was performed in an alkaline agarose solution. The sizes of Fe3O4 nanoparticles and agarose micro-flakes were 10–14 nm and 90–130 μm, respectively. The nanomagnetic agarose particles were functionalized by iminodiacetic acid and subjected to magnetic field agitation in the MFA device. The influence of different analytical parameters such as pH, ionic strength, type and volume of desorption solvent and amount of the adsorbent on the preconcentration of Pd(II) were investigated. Eight replicated analysis at the optimized conditions, resulted in a recovery of 94.1% with an RSD of 5.2% for Pd(II). The detection limit of the method (3σ) was 47 ng L−1 for the analyte. The method was successfully applied to the determination of Pd(II) in natural water samples. 相似文献
108.
A series of β‐hydroxynitriles were efficiently synthesized from the regioselective ring opening of oxiranes by cyanide anion in the presence of silica‐bound 3‐{2‐[poly(ethylene glycol)]ethyl}‐substituted 1‐methyl‐1H‐imidazol‐3‐ium bromide (SiO2? PEG? ImBr) as a novel recoverable phase‐transfer catalyst in H2O (Scheme 1 and Table 2). The workup procedure was straightforward, and the catalyst could be reused over four times with almost no loss of catalytic activity and selectivity. 相似文献
109.
Mohammad Navid Soltani Rad Somayeh Behrouz Abdollah Movahedian Mohammad Mahdi Doroodmand Younes Ghasemi Sara Rasoul‐Amini Abdol‐Rasoul Ahmadi Gandomani Ramin Rezaie 《Helvetica chimica acta》2013,96(4):688-701
A facile and simple protocol for the 1,3‐dipolar cycloaddition of organic azides with terminal alkynes catalyzed by doped nano‐sized Cu2O on melamine? formaldehyde resin (nano‐Cu2O? MFR) as a new and convenient heterogeneous catalyst is described. In this method, ‘click’ cycloaddition of various structurally diverse β‐azido alcohols and alkynes in the presence of nano‐Cu2O? MFR in H2O/THF 1 : 2 furnished the corresponding 1,4‐disubstituted 1H‐1,2,3‐triazole adducts 1a – 1o in good to excellent yields at room temperature (Scheme and Table 3). The nano‐Cu2O? MFR was characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), inductively coupled plasma (ICP) analysis, and FT‐IR. The nano‐Cu2O? MFR could be easily recovered and recycled from the reaction mixture and reused for many consecutive trials without significant decrease in activity (Table 4). The in vitro antibacterial activities of all synthesized compounds were tested on several Gram‐positive and/or Gram‐negative bacteria (Table 5). The results demonstrate the promising antibacterial activity for some of the synthesized compounds. 相似文献
110.
A simple, efficient and practical procedure for the Biginelli reaction using zinc oxid (ZnO) as a novel and reusable catalyst is described under solvent-free conditions in high yields. The use of this agent is characterized by remarkable reactivity, moderate costs, low toxicity and simple work up procedures. 相似文献