排序方式: 共有180条查询结果,搜索用时 46 毫秒
101.
Tavakol Hossein Shahabi Dana Keshavarzipour Fariba Hashemi Fatemeh 《Structural chemistry》2020,31(1):399-409
Structural Chemistry - In this work, the interactions between simple carbon nanotubes (CNTs) and doped carbon nanotubes (DCNTs; with sulfur, boron, aluminum, silicon, phosphorus, or nitrogen) as... 相似文献
102.
Daryoush Afzali Mina Rouhani Fariba Fathirad Ali Mostafavi 《International journal of environmental analytical chemistry》2013,93(14-15):1452-1462
In the present study, multiwalled carbon nanotubes (MWCNTs) as solid phase extraction sorbent were developed for preconcentration of arsenic(V) species prior to graphite furnace atomic absorption spectrometry (GFAAS) determination. Arsenic(V) was selectively sorbed on the packed column with MWCNTs within a pH 9.5 in the presence of 2-(5-bromo-2-pyridylazo)-5-diethyl amino phenol (5-Br-PADAP). The adsorbed species was then desorbed with 1 mL of 2.0 M HNO3. Experimental parameters including pH, sample volume and flow rate, type, volume and concentration of eluent that influence the recovery of the arsenic(V) species were optimised. Under the optimised conditions, the calibration curve was linear in the range of 0.2–10.0 µg L?1 with detection limit of 0.016 µg L?1. The relative standard deviations (RSD) for seven replicate determinations at 1.0 µg L?1 level of arsenic was 6.69%. The proposed method was successfully applied to the determination of arsenic in water samples and certified reference material (NIST RSM 1643e). 相似文献
103.
Masoud Rahman Dr. Fariba Tajabadi Leyla Shooshtari Dr. Nima Taghavinia 《Chemphyschem》2011,12(5):966-973
Hollow structures show both light scattering and light trapping, which makes them promising for dye‐sensitized solar cell (DSSC) applications. In this work, nanoparticulate hollow TiO2 fibers are prepared by layer‐by‐layer (LbL) self‐assembly deposition of TiO2 nanoparticles on natural cellulose fibers as template, followed by thermal removal of the template. The effect of LbL parameters such as the type and molecular weight of polyelectrolyte, number of dip cycles, and the TiO2 dispersion (amorphous or crystalline sol) are investigated. LbL deposition with weak polyelectrolytes (polyethylenimine, PEI) gives greater nanoparticle deposition yield compared to strong polyelectrolytes (poly(diallyldimethylammonium chloride), PDDA). Decreasing the molecular weight of the polyelectrolyte results in more deposition of nanoparticles in each dip cycle with narrower pore size distribution. Fibers prepared by the deposition of crystalline TiO2 nanoparticles show higher surface area and higher pore volume than amorphous nanoparticles. Scattering coefficients and backscattering properties of fibers are investigated and compared with those of commercial P25 nanoparticles. Composite P25–fiber films are electrophoretically deposited and employed as the photoanode in DSSC. Photoelectrochemical measurements showed an increase of around 50 % in conversion efficiency. By employing the intensity‐modulated photovoltage and photocurrent spectroscopy methods, it is shown that the performance improvement due to addition of fibers is mostly due to the increase in light‐harvesting efficiency. The high surface area due to the nanoparticulate structure and strong light harvesting due to the hollow structure make these fibers promising scatterers in DSSCs. 相似文献
104.
The thermodynamics and mechanism of the reaction of elemental mercury with ozone has been studied computationally. The effect of water and water dimer molecules on the reaction has also been investigated. For dry reaction, we obtained two pathways and geometry optimization, atoms in molecules analysis and vibrational frequencies of all component of reaction have been used for confirming of reaction mechanism. Thermodynamic variable of reaction has been calculated. For the reaction in the presence of the water, our studies focus on ozone‐mercury complex reaction with water and water dimer and obtained the mechanism of reactions. Comparison of wet and dry reaction shows the energy profile of reaction decreases with water molecule correspond to experimental prediction. Calculated thermodynamic variable of all reaction shows the Gibbs free energy of reaction decreases with the number of water molecule. 相似文献
105.
The influence of halogen-bonding cooperativity on the hydrogen and lithium bonds: an ab initio study
Mehdi D. Esrafili Parisasadat Mousavian Fariba Mohammadian-Sabet 《Molecular physics》2013,111(14):1903-1911
ABSTRACTAb initio calculations are carried out to study linear NCH···(NCX)1–5 and NCLi?…?(NCX)1–5 clusters (X?=?F, Cl, Br). The aim is to study the influence of halogen-bonding cooperativity on the strength and bonding properties of hydrogen or lithium bond. Particular attention is given to parameters such as binding distances, interaction energies and cooperative energies in these systems. According to our results, the halogen-bonding cooperativity between the NCX molecules has an enhancing effect on the strength of hydrogen and lithium bonds, with an increase of 0.33–0.93 and 0.19–0.43?kcal/mol in NCH···(NCX)n and NCLi···(NCX)n, respectively. The enhancing effect of halogen bond on the hydrogen and lithium bond is dependent on the nature of halogen atom, and increases as X?=?F?相似文献
106.
Heshmat Allah Samimi Fariba Mohammadian-Sabet Hedayat Haddadi 《Molecular physics》2013,111(12):1442-1450
The mutual influence between anion–π and chalcogen bond interactions is studied by ab initio calculations at the MP2/6-311++G** level of theory. These effects are analysed in detail in terms of the structural, energetic, charge-transfer and electron density properties of the complexes. Interesting cooperativity effects are found when anion–π and chalcogen-bonding interactions coexist in the same complex. The effect of anion–π on the properties of chalcogen bonding is larger than that of chalcogen bonding on the properties of anion–π. The cooperative mechanism is analysed in terms of the electrostatic potentials, orbital interaction and electron density analysis. 相似文献
107.
Mohammad Ali Kamyabi Fatemeh Soleymani‐Bonoti Fariba Alirezaei Rahman Bikas Nader Noshiranzadeh Marzieh Emami Marta S. Krawczyk Tadeusz Lis 《应用有机金属化学》2019,33(12)
A new dinuclear cobalt(III) coordination compound, [Co2L(μ‐N3)(N3)2]·CH3OH ( 1 ), was synthesized and characterized by elemental analysis, spectroscopic methods, and single‐crystal X‐ray analysis in which H3L is a heptadentate ligand obtained by the condensation of triethylenetetramine with 5‐bromo‐2‐hydroxybenzaldehyde. X‐ray analysis revealed that two cobalt(III) ions have distorted octahedral geometry and are connected together by a phenoxy and an azide bridging ligand. The catalytic activity of compound 1 for oxygen (O2) reduction reaction was investigated. Compound 1 can efficiently catalyze the reduction of O2 by a weak electron donor, ferrocene (Fc), at the polarized water–1,2‐dichloroethane interface. It was found that compound 1 can catalyze O2 reduction to H2O2, whereas in the presence of Fc, it can catalyze the reduction of O2 to water. 相似文献
108.
Boehmite (BO) nanoparticles (NPs) were prepared via the injection of aqueous NaOH solution to aqueous aluminum nitrate solution at room temperature. Afterwards, a new complex of copper was immobilized on BO-NPs (Cu-Guanidine@BO-NPs). This heterogeneous nanocatalyst was used as a practical, recyclable, chemo and homoselective nanocatalyst in the organic processes, i.e. the preparation of tetrazole five-membered heterocycles and chemoselective sulfoxidation of sulfides using H2O2 as oxidant. In this sense, the prepared nanocatalyst was characterized by AAS, N2 adsorption–desorption isotherms, WDX, EDS, SEM, and TGA techniques. The reusability of this catalyst was investigated in the described organic reactions for several runs without notable loss of its catalytic activity. Moreover, all of the tetrazole and sulfoxide derivatives were isolated in high Turn Over Number (TON) and Turn Over Frequency (TOF) numbers indicating the high activity and selectivity of Cu-Guanidine@BO-NPs in the described reactions. 相似文献
109.
Dadkhoda Ghazanfari Fariba Najafizadeh Fereshteh Khosravi 《Monatshefte für Chemie / Chemical Monthly》2004,42(9):1409-1413
4-Aminoperoxybenzoic acid supported on silica gel in presence of air was found to be a selective and convenient oxidant for the oxidation of methylene groups in aryl ketones to convert them to -diketones. 相似文献
110.
The dual role of halogen,chalcogen, and pnictogen atoms as Lewis acid and base: Triangular XBr:SHX:PH2X complexes (X = F,Cl, Br,CN, NC,OH, NH2, and OCH3)
下载免费PDF全文
![点击此处可从《International journal of quantum chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mehdi D. Esrafili Fariba Mohammadian‐Sabet Mohammad Mehdi Baneshi 《International journal of quantum chemistry》2015,115(22):1580-1586
Using ab initio calculations, we have investigated the possibility of formation of triangular XBr:SHX:PH2X complexes, where X = F, Cl, Br, CN, NC, OH, NH2, and OCH3. These complexes are formed through the interaction of a positive electrostatic potential region (σ‐hole) on a molecule with the negative region in another one. The results show that the combined halogen, chalcogen, and pnictogen interactions can give rise to stable cyclic structures. The interaction energies of these complexes span over a wide range, from ?3.55 to ?24.93 kcal/mol. Nice quadratic correlations are found between the interaction energies and binding distances in the trimers. To understand the nature of the interactions in these complexes, molecular electrostatic potential and quantum theory of atoms in molecule analyses are performed. © 2015 Wiley Periodicals, Inc. 相似文献