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11.
Harding CJ Kunz S Habibpour V Heiz U 《Physical chemistry chemical physics : PCCP》2008,10(38):5875-5881
The catalysed oxidation of CO using mass-selected Pd(13) clusters supported on thin MgO films was modelled using a microkinetic simulation of the reaction. The model of the system includes reverse spill-over calculations which were intrinsically incorporated into the formulation of the kinetics. The spill-over model is based on a capture-zone approach including a co-dependence on the variables of the kinetic equations. The experimental values were determined using dual pulsed-molecular beam measurements and recorded at a range of temperatures. The experiment allowed the turn-over frequency and reaction probability to be determined as a function of mole fraction. Comparison of the kinetic model with the experimental data gives excellent agreement and strongly highlights the importance of substrate effects. In particular, the origin of the low temperature catalysis of the Pd clusters is elucidated. The model allows the mole fraction and temperature dependent values such as the sticking coefficients for these clusters to be predicted. 相似文献
12.
In this paper, a novel scheme for nonlinear displacement-dependent (NDD) damper is introduced. The damper is attached to a simple mass-spring-damper vibration system. The vibration system equipped with a NDD damper is mathematically modeled and the nonlinear governing differential equation of the system is derived. To obtain the displacement of the system, the approximate analytical solution of the governing equation is elaborated using the multiple scales method. The advised approximate analytical algorithm is performed for several case studies and is also verified by the numerical fourth-order Runge?CKutta method. In addition, the performance of the NDD damper is analyzed and compared with the performance of the traditional linear damper. It is found that the proposed NDD damper scheme along with the multiple scales method is not only feasible for vibration reduction but also yields satisfactory response performance rather than the existing traditional linear damper. 相似文献
13.
Sara Hosseinzadeh-Baghan Masoud Mirzaei Hossein Eshtiagh-Hosseini Vahideh Zadsirjan Majid M. Heravi Joel T. Mague 《应用有机金属化学》2020,34(9):e5793
A novel inorganic–organic hybrid, [Dy4(PDA)4(H2O)11(SiMo12O40)]·7H2O denoted as (POM@Dy-PDA), based on a lanthanide cluster, a Keggin-type polyoxomolybdate, and PDA (1,10-phenanthroline-2,9-dicarboxylic acid) was prepared and fully characterized by elemental analysis, Fourier-transform infrared and UV–Vis spectroscopies, thermogravimetric analysis, powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction. The structural analysis study showed that the [SiMo12O40]4− ions reside in the interspace between two cationic layers as discrete counterions and are not coordinated to the rare-earth ions. Significantly, this hybrid catalyst is a rare case of an inorganic–organic hybrid polyoxometalate (POM) with a PDA ligand based on CSD search (CSD version 5.40/November2018). The hybrid catalyst was further characterized via powder X-ray diffraction (PXRD) pattern at room temperature which indicated the good phase purity of the catalyst. BET and Langmuir surface area analysis indicate surface area of POM@Dy-PDA 6.6 and 51.3 m2g-1, respectively. The catalytic activity of the hybrid catalyst was successfully examined in the synthesis of 2-amino-4H-chromene derivatives through a multicomponent reaction. A three-component, one-pot reaction involving differently substituted benzaldehydes, resorcinol/α-naphthol/β-naphthol/4-hydroxycoumarin/3-methyl-4H-pyrazole-5(4H)-one, and malononitrile or ethyl cyanoacetate in the presence of a catalytic quantity of the aforementioned hybrid catalyst in EtOH/H2O under reflux condition gave the corresponding highly functionalized 2-amino-4H-chromenes in satisfactory yields. The catalyst can be reused several times without appreciable loss in its catalytic activity. 相似文献
14.
In this report, we try to show the importance of incorporation of name reactions in the sequential cascade reaction in which significantly decreasing the number of steps towards an ideal and practical multi-step synthesis of natural products as well showing virtually all the advantages already mentioned for “Click Chemistry”. In addition, since the chiral inductions are desired for most of these sequential name reactions, their asymmetric catalyzed reactions were also described. 相似文献
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16.
Mohammad Hakimi Reza Takjoo Vahideh Erfaniyan Esther Schuh Fabian Mohr 《Transition Metal Chemistry》2010,35(8):959-965
Two complexes of a thiosemicarbazone ligand, namely N-(2-hydroxyethyl)-2-(thiophene-2-ylmethylene)-hydrazinecarbothioamide (HL), have been synthesized. The complexes have been
characterized by physico-chemical and spectroscopic methods. The crystal and molecular structures of [CoL3]·2MeOH (1) and [NiL2] (2) have been determined by X-ray diffraction studies. For both complexes, the metal is coordinated through the sulfur and azomethine
nitrogen atoms of the thiosemicarbazone. The ligand exists in its thiolate tautomeric form, and the central Co(III) and Ni(II)
atoms have distorted octahedral and square planar geometries, respectively, with five-membered chelate rings formed by the
ligand. The lattice of 1 shows infinite oxygen donor/acceptor hydrogen bonds in the ab plane and weak interactions between rings along the c axis, respectively, giving a supramolecular network. The molecular units in 2 are linked together by hydrogen bonds between the hydroxyl oxygen and hydrazone N proton, giving rise to an infinite ribbon
extended along the c-axis. These chains are connected by N3–H3···O1 interactions that form a sheet within the ac plane. 相似文献
17.
Heravi Majid M. Malakooti Reihaneh Kafshdarzadeh Kosar Amiri Zahra Zadsirjan Vahideh Atashin Hassan 《Research on Chemical Intermediates》2022,48(1):203-234
An eco-friendly method for diversity-oriented synthesis of substituted dihydropyrano[2,3-c]pyrazole and benzylpyrazolyl coumarin derivatives has been achieved via one-pot and multicomponent reaction in the presence of PdO/Al-SBA-15 as an efficient and recyclable catalyst in H2O/EtOH under reflux conditions. The significant merits of this method are wide scope, high yields of the desired products, short reaction times and simple workup procedure. In addition, this nanocatalyst was simply recovered and reused five times without significant loss in catalytic activity and also performance.
Graphical abstract18.
Vahideh Mahdavi Hamideh Hamidi 《International journal of environmental analytical chemistry》2013,93(14):1342-1351
ABSTRACTA fast, selective and sensitive reversed-phased liquid chromatography coupled to ion-trap mass spectrometry has been developed to elucidate and confirm the diazinon metabolites with a wide range of polarity in the rice plant samples. Sample extraction and purification were performed with a QuEChERS-based (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure. To boost all metabolism sensitivities, all rice extracts were concentrated under vacuum to near dryness and taken up into initial mobile phase. Careful optimisation of the LC–MS/MS parameters were achieved in order to attain a fast separation with the best sensitivity. The detection was carried out on an ion-trap mass spectrometer by electrospray ionisation in positive ion mode (ESI+) with multiple reaction monitoring. 相似文献
19.
Younes Valadbeigi Vahideh Ilbeigi Maryam S. Mirsharifi 《Journal of mass spectrometry : JMS》2020,55(10)
Atmospheric pressure chemical ionizations (APCIs) of morphine, codeine, and thebaine were studied in a corona discharge ion source using ion mobility spectrometry (IMS) at temperature range of 100°C–200°C. Density functional theory (DFT) at the B3LYP/6‐311++G(d,p) and M062X/6‐311++G(d,p) levels of theory were used to interpret the experimental data. It was found that in the presence of H3O+ as reactant ion (RI), ionization of morphine and codeine proceeds via both the protonation and carbocation formation, whereas thebaine participates only in protonation. Carbocation formation (fragmentation) was diminished with decrease in the temperature. At lower temperatures, proton‐bound dimers of the compounds were also formed. Ammonia was used as a dopant to produce NH4+ as an alternative RI. In the presence of NH4+, proton transfer from ammonium ion to morphine, codeine, and thebaine was the dominant mechanism of ionization. However, small amount of ammonium attachment was also observed. The theoretical calculations showed that nitrogen atom of the molecules is the most favorable proton acceptor site while the oxygen atoms participate in ammonium attachment. Furthermore, formation of the carbocations is because of the water elimination from the protonated forms of morphine and codeine. 相似文献
20.
Majid M. Heravi Vahideh Zadsirjan Elham Kouhestanian Behnoush AlimadadiJani 《Chemical record (New York, N.Y.)》2020,20(4):273-331
One of the most important name reactions in organic chemistry, is the Diels‐Alder cycloaddition reaction. It is a chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile to construct a substituted cyclohexene derivative. It is the stereotypical example of a pericyclic reaction with a concerted mechanism. In synthesis, the use of electricity instead of stoichiometric amounts of oxidant or reducing agents is definitely appealing for economic, ecological and selective, reasons. In this review, we try to underscore the combination of the electrosynthesis with Diels‐Alder cycloaddition reaction to establish of a powerful synthetic tool which may encourage synthetic organic chemists to use it in the future. 相似文献