排序方式: 共有135条查询结果,搜索用时 31 毫秒
61.
Serpil Demir?smail Özdemir Bekir ÇetinkayaHakan Arslan Don VanDerveer 《Polyhedron》2011,30(1):195-200
The new well-defined and air-stable ortho-xylyl-linked N-heterocyclic carbene (NHC) Pd complexes (2a-d) have been synthesized and characterized by elemental analysis, 1H NMR, 13C NMR, IR spectroscopy, and single crystal X-ray diffraction studies. The palladium atom in the complex 2a lies on a crystallographic mirror plane and can be described as having a square-planar coordination environment with the carbene atoms of the benzimidazole rings of the ligand occupying two coordination sites in cis positions. Two further coordination sites are occupied by chloride ligands. The benzimidazole rings are connected to each other by an ortho-xylyl bridge. The catalytic activity of these palladium complexes has been tested in the coupling reactions of various N-containing substrates with bromobenzene. A preliminary catalytic study shows that the bis(NHC)-Pd complexes are highly active in the Buchwald-Hartwig amination reaction. 相似文献
62.
Improvement of catalytic properties of Candida rugosa lipase by sol-gel encapsulation in the presence of magnetic calix[4]arene nanoparticles 总被引:1,自引:0,他引:1
Candida rugosa lipase (CRL) was encapsulated within a chemically inert sol-gel support prepared by polycondensation with tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) in the presence of N-methylglucamine based calix[4]arene magnetic nanoparticles. The results indicate that the magnetic calix[4]arene based encapsulated lipase particularly has shown high conversion and enantioselectivity. It has also been noticed that the magnetic calix[4]arene based encapsulated lipase has excellent enantioselectivity (E = 460) as compared to the free enzyme (E = 166) with an ee value of >98% for S-Naproxen. 相似文献
63.
Hüseyin Deligöz Mesut Yılmazoğlu Serpil Yılmaztürk Yavuz Şahin Kemal Ulutaş 《先进技术聚合物》2012,23(8):1156-1165
The paper deals with the synthesis and characterization of a new series of anhydrous conducting acid‐doped complex membranes based on polyimide (PI) and ionic liquid (IL) for high‐temperature fuel cells via a new route. For this purpose, three imidazolium‐based ILs (RIm+BF4?) with different alkyl chain lengths (R=methyl, ethyl, and butyl) are added into polyamic acid (PAA) intermediate prepared from the reaction of benzophenonetetracarboxylic dianhydride and diaminodiphenylsulfone in different –COOH/imidazolium molar ratios (n = 0.5, 1, and 2). Then, the thermally imidized complex membrane was doped with H2SO4. The conductivities of acid‐doped PI/IL complex membranes prepared by taking n of 1 are found to be in the range of 10?4?10?5 S cm?1 at 180°C, whereas the acid‐free PI/IL complex membranes show the conductivity at around 10?9?10?10 S cm?1. Thermogravimetric analysis results reveal that the acid‐doped PI/IL complex membranes are thermally stable up to 250°C. Dynamic mechanical analysis results of the acid‐doped ionically interacted complex membrane show that the mechanical strengths of the PI/IL complex membranes including 1‐methyl imidazolium tetrafluoroborate (MeIm‐BF4) and 1‐ethyl 3‐methyl imidazolium tetrafluoroborate (EtIm‐BF4) are comparable with those of pristine PI until 200°C. Furthermore, it can be clearly emphasized that the ionic interaction between carboxylic acid groups of PAA's and IL's cations offers a positive role in long‐term conductivity stability by preventing the IL migration at high temperatures. On the other hand, preliminary methanol permeability tests of the acid‐doped membranes show that they can also be considered as an alternative for direct methanol fuel cells. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
64.
A novel 1‐(cyclobutylmethyl)‐substi‐tuted imidazolidinium/benzimidazolium salts as N‐heterocyclic carbene (NHC) precursors were successfully synthesized and characterized by 1H NMR, 13C NMR, IR, and elemental analysis techniques. These compounds were easily prepared from the reaction of N‐alkyl imidazoline/N‐alkyl benzimidazole with bromomethylcyclobutane in high yields. The in situ formed catalytic system derived from the NHC precursor and Pd(OAc)2 was used in the Heck reaction between aryl halides and styrene with potassium hydroxide in water. The corresponding Heck products were obtained in good yields. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:77–83, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21065 相似文献
65.
Hüseyin Deligöz Serpil YılmaztürkTuba Karaca Hasan ÖzdemirS. Naci Koç Faruk ÖksüzömerAli Durmuş M. Ali Gürkaynak 《Journal of membrane science》2009
The paper is concerned with the deposition of self-assembled polyelectrolyte multilayer on Nafion membrane by layer-by-layer (LbL) technique with lowered methanol cross-over for direct methanol fuel cell (DMFC) applications. The formation of self-assembled multilayered film on Nafion was characterized by UV–vis spectroscopy and it was found that the polyelectrolyte layers growth on the Nafion surface regularly. Furthermore, the proton conductivity and methanol cross-over measurements were carried out for characterization of the LbL self-assembled composite membranes. The results showed that the concentration and pH of the polyelectrolytes significantly affect the proton conductivity and methanol barrier properties of the composite membranes. 10−1 monomol polyelectrolyte concentration and pH 1.8 was found to be optimum deposition conditions considering proton conductivity and methanol permeation properties of the LbL self-assembled composite membranes. The methanol permeability of the 10 bi-layers of PAH1.8/PSS1.8 deposited LbL self-assembly composite membrane was significantly suppressed and found to be 4.41 × 10−7 cm2/s while the proton conductivity value is in acceptable range for fuel cell applications. 相似文献
66.
Huseyin Sari Esin Kasapoglu Unal Yesilgul Serpil Sakiroglu Fatih Ungan Ismail Sökmen 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(9):162
The effect of non-resonant intense laser field on the intersubband-related optical absorption coefficient and refractive index change in the asymmetric n-type double δ-doped GaAs quantum well is theoretically investigated. The confined energy levels and corresponding wave functions of this structure are calculated by solving the Schrödinger equation in the laser-dressed confinement potential within the framework of effective mass approximation. The optical responses are reported as a function of the δ-doped impurities density and the applied non-resonant intense laser field. Additionally, the calculated results also reveal that the non-resonant intense laser field can be used as a way to control the electronic and optical properties of the low dimensional semiconductor nano-structures. 相似文献
67.
68.
Serpil Halici 《Advances in Applied Clifford Algebras》2015,25(4):905-914
69.
The gamma-irradiated single crystals of 2-Bromo-4′-methoxyaceto-phenone (2B4MA) were investigated using electron paramagnetic resonance (EPR) technique. Density-functional theory calculations were employed to investigate and identify the radicals that have been assumed to be formed upon irradiation of 2B4MA single crystals. The EPR spectra of 2B4MA were recorded at different orientations in the magnetic field at room temperature. Taking into account the chemical structure and experimental spectra of irradiated single crystal of 2B4MA, it was assumed that at least two different radicals were produced in the sample. Following this assumption, six possible radicals were modeled and EPR parameters were calculated by using the DFT, B3LYP/6-311+G(d), for the modeled radicals individually. The calculated hyperfine coupling constants and g-tensors were used as initial values for simulation studies. The three crystallographic axes on the simulated spectra were well matched with experimental spectra for the two modeled radicals. Thus, we identified the R1 type radical and R4 type radical as paramagnetic species produced in gamma-irradiated 2B4MA. 相似文献
70.
Muhammet Işıklan Levent Sayın Ömer Sonkaya Tuncer Hökelek Mustafa Türk Serpil Oğuztüzün 《Phosphorus, sulfur, and silicon and the related elements》2016,191(9):1216-1222
Octachlorocyclotetraphosphazene, N4P4Cl8, (1) was reacted with N, N′-dibenzylethylenediamine to synthesize partially substituted monospiro- (2), dispiro- (5) and tetraspirocyclotetraphosphazene (8) derivatives. The reactions of 2 and 5 with excess pyrrolidine and morpholine produced fully substituted pyrrolidino (3 and 6) and morpholino (4 and 7) spirocyclotetraphosphazenes. The structures of the compounds were determined with 1D (1H, 13C, 31P, and DEPT) NMR, 2D (HSQC) NMR, ESI-MS, FTIR, and elemental analysis. The solid-state structures of 6 and 7 were examined by X-ray crystallography. In 7, intramolecular C-H…O hydrogen bonds link the molecules into centrosymmetric dimmers. The cytotoxic activity of all the compounds against human cervix carcinoma cell lines (HeLa) was investigated. The study showed that these compounds exert limited cytotoxic, apoptotic and necrotic effects on HeLa cancer cell lines. 相似文献