首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 812 毫秒
1.
Cu(II) immobilized on mesoporous organosilica nanoparticles (Cu2+@MSNs‐(CO2?)2) has been synthesized, as a inorganic–organic nanohybrid catalyst, through a post‐grafting approach. Its characterization is carried out by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Energy dispersive X‐ray (EDX), Thermogravimetric/differential thermal analyses (TGA‐DTA), and Nitrogen adsorption–desorption analysis. Cu2+@MSNs‐(CO2?)2 exhibits high catalytic activity in the Biginelli reaction for the synthesis of a diverse range of 3, 4‐dihydropyrimidin‐2(1H)‐ones, under mild conditions. The anchored Cu(II) could not leach out from the surface of the mesoporous catalyst during the reaction and it has been reused several times without appreciable loss in its catalytic activity.  相似文献   

2.
One new two‐dimensional (2D) CuII polymer [Cu(CHDA)(H2O)]n ( 1 ) was synthesized solvothermally based on 1,1‐cyclohexanediacetic acid (H2CHDA) ligand. Single‐crystal X‐ray diffraction analysis reveals that 1 has a 2D framework structure consisting of paddle‐wheel dinuclear [Cu2] cluster unit and CHDA2– connector, which bears a 4‐connected sql network with Schläfli symbol of (44.62). Magnetic studies indicate the presence of strong antiferromagnetic coupling (J = –302 cm–1) between the two CuII ions in the paddle‐wheel dicopper(II) entity.  相似文献   

3.
SnS2/polypyrrole (PPy) composites were successfully synthesized by PPy modification of SnS2 via a simple and effective solvothermal and chemical method. The microstructure, morphology, electrical conductivity, PPy content, and electrochemical properties of these materials were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), four‐point probe technique, thermogavimetry (TG), and constant‐current charge/discharge tests, respectively. The results demonstrate that PPy is tightly coated on the 3D flower‐like SnS2 and that the conductivity of SnS2 /PPy composites can be greatly improved by the PPy modification. The electrochemical results indicate that PPy is not involved in the electrode reaction, but it can dramatically improve the reversible capacity and cyclic performance. The recharge capacity retention after 30 cycles remained at 523 mAh/g, which is significantly higher than that of SnS2 without modification by PPy. The better cycling performance compared to SnS2 nanoparticles should be due to the 3D nano‐flower‐like SnS2 particles and the modification of SnS2 by PPy.  相似文献   

4.
Cyanide as a bridge can be used to construct homo‐ and heterometallic complexes with intriguing structures and interesting magnetic properties. These ligands can generate diverse structures, including clusters, one‐dimensional chains, two‐dimensional layers and three‐dimensional frameworks. The title cyanide‐bridged CuII–CoIII heterometallic compound, [CuIICoIII(CN)6(C4H11N2)(H2O)]n, has been synthesized and characterized by single‐crystal X‐ray diffraction analysis, magnetic measurement, thermal study, vibrational spectroscopy (FT–IR) and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy (SEM–EDS). The crystal structure analysis revealed that it has a two‐dimensional grid‐like structure built up of [Cu(Hpip)(H2O)]3+ cations (Hpip is piperazinium) and [Co(CN)6]3− anions that are linked through bridging cyanide ligands. The overall three‐dimensional supramolecular network is expanded by a combination of interlayer O—H...N and N—H...O hydrogen bonds involving the coordinated water molecules and the N atoms of the nonbridging cyanide groups and monodentate cationic piperazinium ligands. A magnetic investigation shows that antiferromagnetic interactions exist in the title compound.  相似文献   

5.
In the present work, an innovative leach proof nanocatalyst based on dendritic fibrous nanosilica (DFNS) modified with ionic liquid loaded Fe3O4 NPs and CuI salts was designed and applied for the rapid synthesis of imidazo[1,2‐a]pyridines from the reaction of phenyl acetylene, 2‐aminopyridine, and aldehydes in aqueous medium. The structure of the synthesized nanocatalyst was studied by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), flame atomic absorption spectroscopy (FAAS), energy‐dispersive X‐ray (EDX), and X‐ray diffraction (XRD), vapor–liquid–solid (VLS), and adsorption/desorption analysis (Brunauer–Emmett–Teller [BET] equation) instrumental techniques. CuI/Fe3O4NPs@IL‐KCC‐1 with high surface area (225 m2 g?1) and porous structure not only exhibited excellent catalytic activity in aqueous media but also, with its good stability, simply recovered by an external magnet and recycled for eight cycles without significant loss in its intrinsic activity. Higher catalytic activity of CuI/Fe3O4NPs@IL‐KCC‐1 is due to exceptional dendritic fibrous structure of KCC‐1 and the ionic liquid groups that perform as strong anchors to the loaded magnetic nanoparticles (MNPs) and avoid leaching them from the pore of the nanocatalyst. Green reaction media, shorter reaction times, higher yields (71–97%), easy workup, and no need to use the chromatographic column are the advantages of the reported synthetic method.  相似文献   

6.
A novel porous copper‐based metal‐organic framework {[Cu2(TTDA)2]*(DMA)7}n ( 1 ) (DMA = N,N‐dimethylacetamide) was designed and synthesized via the combination of a dual‐functional organic linker 5′‐(4‐(4H‐1,2,4‐triazol‐4‐yl)phenyl)‐[1,1′:3′,1′′‐terphenyl]‐4,4′′‐dicarboxylic acid (H2TTDA) and a dinuclear CuII paddle‐wheel cluster. This MOF is characterized by elemental analysis, powder X‐ray diffraction (PXRD), thermo gravimetric analysis (TGA), and single‐crystal X‐ray diffraction. The framework is constructed from two types of cages (octahedral and cuboctahedral cages) and exhibits two types of circular‐shaped channels of approximate size of 5.8 and 11.4 Å along the crystallographic c axis. The gas sorption experiments indicate that it possesses a large surface area (1687 m2 · g–1) and high CO2 adsorption capacities around room temperature (up to 172 cm3 · g–1 at 273 K and 124 cm3 · g–1 at 298 K).  相似文献   

7.
The 2D CuII metal‐organic framework [Cu2(bptc)(H2O)4]n · 4nH2O ( 1 ) (H4bptc = biphenyl‐2,2′,4,4′‐tetracarboxylic acid) was hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction and magnetic measurements. In the structure, bptc4– serves as a twisted Π‐shaped organic building block to connect paddlewheel [Cu2(COO)4] dinuclear units and mononuclear units through 2‐/2′‐carboxylate and 4‐/4′‐carboxylate, respectively. According to the magnetic analysis using a dimer‐plus‐monomer model, strong antiferromagnetic coupling is operative within the dinuclear unit (J = –311 cm–1 based on H = –J S 1 S 2), and the compound behaves like a mononuclear molecule at low temperature.  相似文献   

8.
To gain insight into the underlying mechanisms of catalyst durability for the selective catalytic reduction (SCR) of NOx with an ammonia reductant, we employed scanning transmission X‐ray microscopy (STXM) to study Cu‐exchanged zeolites with the CHA and MFI framework structures before and after simulated 135 000‐mile aging. X‐ray absorption near‐edge structure (XANES) measurements were performed at the Al K‐ and Cu L‐edges. The local environment of framework Al, the oxidation state of Cu, and geometric changes were analyzed, showing a multi‐factor‐induced catalytic deactivation. In Cu‐exchanged MFI, a transformation of CuII to CuI and CuxOy was observed. We also found a spatial correlation between extra‐framework Al and deactivated Cu species near the surface of the zeolite as well as a weak positive correlation between the amount of CuI and tri‐coordinated Al. By inspecting both Al and Cu in fresh and aged Cu‐exchanged zeolites, we conclude that the importance of the preservation of isolated CuII sites trumps that of Brønsted acid sites for NH3‐SCR activity.  相似文献   

9.
Magnetic silica‐coated magnetite (Fe3O4) sub‐microspheres with immobilized metal‐affinity ligands are prepared for protein adsorption. First, magnetite sub‐microspheres were synthesized by a hydrothermal method. Then silica was coated on the surface of Fe3O4 particles using a sol–gel method to obtain magnetic silica sub‐microspheres with core‐shell morphology. Next, the trichloro(4‐chloromethylphenyl) silane was immobilized on them, reacted with iminodiacetic acid (IDA), and charged with Cu2+. The obtained magnetic silica sub‐microspheres with immobilized Cu2+ were applied for the absorption of bovine hemoglobin (BHb) and the removal of BHb from bovine blood. The size, morphology, and magnetic properties of the resulting magnetic micro(nano) spheres were investigated by using scanning microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and a vibrating sample magnetometer (VSM). The measurements showed that the magnetic sub‐microspheres are spherical in shape, very uniform in size with a core‐shell, and are almost superparamagnetic. The saturation magnetization of silica‐coated magnetite (Fe3O4) sub‐microspheres reached about 33 emu g?1. Protein adsorption results showed that the sub‐microspheres had a high adsorption capacity for BHb (418.6 mg g?1), low nonspecific adsorption, and good removal of BHb from bovine blood. This opens a novel route for future applications in removing abundant proteins in proteomic analysis.  相似文献   

10.
以氯化亚铜,硝酸锌,氯化锡和硫脲作为反应前驱体,聚乙二醇作为模板,利用溶剂热方法合成Cu2ZnSnS4中空球。其中,聚乙二醇对于产物的最终形成起到关键作用。文章讨论了Cu2ZnSnS4中空球的生长机制,并通过X射线衍射(XRD)、拉曼光谱、场发射电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)、X射线光电子谱(XPS)、选区电子衍射谱(SAED)和紫外-可见光分光光度计(UV-Vis)等技术对样品的微结构以及光学性质进行了表征和分析。结果显示Cu2ZnSnS4中空球为四方晶体,尺寸为600 nm。其禁带宽度为1.52 eV,适用于制作光伏器件。  相似文献   

11.
A double azido‐bridged CuII dinuclear complex with the chelating chiral ligand, [Cu2(L)2(N3)4] ( 1 ) [L = (+)‐2, 2′‐isopropylidene‐bis((4R)‐4‐benzyl‐2‐oxazoline)] was synthesized and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, magnetic measurements, and theoretical studies. The asymmetric double end‐on azido bridges in complex 1 lead to a weak antiferromagnetic behavior with J = –7.4 cm–1. The exchange interactions in complex 1 were investigated by DFT calculations, and the calculated exchange interaction (J = –8.0 cm–1) is in good agreement with the experimental value.  相似文献   

12.
Copper and cobalt substituted spinel ferrites Cu1‐xCoxFe2O4 (0≤X≤1) have been synthesized by using hydrothermal method. The resultant spinel ferrites were systematically characterized by different techniques such as X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FT‐IR). It was indicated that all the resultant spinel ferrites obtained by the hydrothermal method had the single‐phase crystalline. The resultant spinel ferrites were employed in the synthesis of 14‐aryl‐14‐H‐dibenzo[a,j]xanthene derivatives. It was found that the nanocatalyst Cu0.5Co0.5Fe2O4 displays the best performance in the synthesis of 14‐aryl‐14H‐dibenzo[a,j]xanthenes. The catalyst was reused several times without significant loss of its activity for the preparation of desired product. In addition high yields of the products, solvent‐free conditions and reusability of the catalyst are other worthwhile advantages of the present study.  相似文献   

13.
Summaryof main observation and conclusion In order to extend the absorption spectrum of polyoxo-titanium clusters into the visible region,two new heterometal-oxo clusters Ti4CuII2CuI2(μ3-O)6(benzoate)10(MeCN)4(PTC-153)and Ti4CuII2CuI2(μ3-O)6(benzoate)8(CH3COO)2(MeCN)4(PTC-154)were success-fully synthesized.Single-crystal X-ray diffraction and X-ray photoelectron spectroscopy studies showed that these two heterometallic Ti4Cu4-oxo clusterspossessed Chinese knot-shape structure and mixed valence Cu^1+/2+ions.UV-visible spectroscopyanalysis demonstrated that the visible light region ab-sorption of PTC-153and PTC-154 could be significantly enhanced by doping copper.Furthermore,their visible-light driven photocurrent responses were studied by using samples of PTC-153and PTC-154as electrode precursors.  相似文献   

14.
meso‐Triazolyl‐appended ZnII–porphyrins were readily prepared by CuI‐catalyzed 1,3‐dipolar cycloaddition of benzyl azide to meso‐ethynylated ZnII–porphyrin (click chemistry). In noncoordinating CHCl3 solvent, spontaneous assembly occurred to form tetrameric array ( 3 )2 from mesomeso‐linked diporphyrins 3 , and dodecameric porphyrin squares ( 4 )4 and ( 5 )4 from the L ‐shaped mesomeso‐linked triporphyrins 4 and 5 . The structures of these assemblies were examined by 1H NMR spectra, absorption spectra, and their gel permeation chromatography (GPC) retention time. Furthermore, the structures of the dodecameric porphyrin squares ( 4 )4 and ( 5 )4 were probed by small‐ and wide‐angle X‐ray scattering (SAXS/WAXS) measurements in solution using a synchrotron source. Excitation‐energy migration processes in these assemblies were also investigated in detail by using both steady‐state and time‐resolved spectroscopic methods, which revealed efficient excited‐energy transfer (EET) between the mesomeso‐linked ZnII–porphyrin units that occurred with time constants of 1.5 ps?1 for ( 3 )2 and 8.8 ps?1 for ( 5 )4.  相似文献   

15.
Copper‐doped iron sulfide (CuxFe1?xS, x = 0.010–0.180) thin films were deposited using a single‐source precursor, Cu(LH)2Cl2 (LH = monoacetylferrocene thiosemicarbazone), by aerosol‐assisted chemical vapor deposition technique. The Cu‐doped FeS thin films were deposited at different substrate temperatures, i.e. 250, 300, 350, 400 and 450 °C. The deposited thin films were characterized by X‐ray diffraction (XRD) patterns, Raman spectra, scanning electron microscopy, energy dispersive X‐ray analysis (EDX) and atomic force microscopy. XRD studies of Cu‐doped FeS thin films at all the temperatures revealed formation of single‐phase FeS structure. With increasing substrate temperature from 250 to 450 °C, there was change in morphology from wafer‐like to cylindrical plate‐like. EDX analysis showed that the doping percentage of copper increased as the substrate temperature increased from 250 to 450 °C. Raman data supports the doping of copper in FeS films. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

16.
CuO–ZnO micro/nanoporous array‐films are synthesized by transferring a solution‐dipped self‐organized colloidal template onto a device substrate and sequent heat treatment. Their morphologies and structures are characterized by X‐ray diffraction, field‐emission scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectrum analysis. Based on the sensing measurement, it is found that the CuO–ZnO films prepared with the composition of [Cu2+]/[Zn2+]=0.005, 0.01, and 0.05 all show a nice sensitivity to 10 ppm H2S. Interestingly, three different zones exist in the patterns of gas responses versus H2S concentrations: a platform zone, a rapidly increasing zone, and a slowly increasing zone. Further experiments show that the hybrid CuO–ZnO porous film sensor exhibits shorter recovery time and better selectivity to H2S gas against other interfering gases at a concentration of 10 ppm. These new sensing properties may be due to a depletion layer induced by p–n junction between p‐type CuO and n‐type ZnO and high chemical activity of CuO to H2S. This work will provide a new construction route of ZnO‐based sensing materials, which can be used as H2S sensors with high performances.  相似文献   

17.
The reduced graphene oxide‐Bi2WO6 (rGO‐BWO) photocatalysts with the different RF/O values (molar ratio of the F molar mass and the O's molar mass of Bi2WO6) had been successfully synthesized via one‐step hydrothermal method. The F‐doped rGO‐BWO samples were characterized by X‐ray diffraction patterns (XRD), field‐emission scanning electron microscopy (FE‐ESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X‐ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS). The results indicate that F? ions had been successfully doped into rGO‐BWO samples. With the increasing of the RF/O values from 0 to 2%, the evident change of the morphology and the absorption edges of F‐doped rGO‐BWO samples and the photocatalytic activities had been enhanced. Moreover, the photocatalytic activity of F‐doped rGO‐BWO with RF/O = 0.05 were better than rGO‐BWO and the other F‐doped rGO‐BWO under 500 W Xe lamp light irradiation. The enhanced photocatalytic activity can be attributed to the morphology of the intact microsphere that signify the bigger specific surface area for providing more possible reaction sites for the adsorption–desorption equilibrium of photocatalytic reaction, the introduction of F? ions that may cause the enhancement of surface acidity and creation of oxygen vacancies under visible light irradiation, the narrower band gap which means needing less energy for the electron hole pair transition.  相似文献   

18.
Ferrocene tethered N‐heterocyclic carbene‐copper complex anchored on graphene ([GrFemImi]NHC@Cu complex) has been synthesized by covalent grafting of ferrocenyl ionic liquid in the matrix of graphene followed by metallation with copper (I) iodide. The [GrFemImi]NHC@Cu complex has been characterized by fourier transform infrared (FT‐IR), fourier transform Raman (FT‐Raman), CP‐MAS 13C NMR spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), energy dispersive X‐ray (EDX) analysis, X‐ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area analysis and X‐ray diffractometer (XRD) analysis. This novel complex served as a robust heterogeneous catalyst for the synthesis of bioactive N‐aryl sulfonamides from variety of aryl boronic acids and sulfonyl azides in ethanol by Chan‐Lam coupling. Recyclability experiments were executed successfully for six consecutive runs.  相似文献   

19.
The reactions of 4N‐ethyl‐2‐[1‐(pyrrol‐2‐yl)methylidene(hydrazine carbothioamide ( 4 EL1 ) and 4N‐ethyl‐2[1‐(pyrrol‐2‐yl)ethylidene(hydrazine carbothioamide ( 4 EL2 ) with Group 12 metal halides afforded complexes of types [M(L)2X2] (M = Zn, Cd; L = 4 EL1, 4 EL2; X = Cl, Br, I; 1 – 6 , 14 – 19 ) and [M(L)X2] (M = Hg; L = 4 EL1, 4 EL2; X = Cl, Br, I; 7 – 9 , 20 – 22 ). In addition, reaction of 4 EL1 with salts of CuII, NiII, PdII and PtII afforded compounds of type [M(4 EL1–H)2] ( 10 – 13 ). The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR and electronic spectroscopy and, for sufficiently soluble compounds, 1H, 13C and, when appropriate, 113Cd or 199Hg NMR spectrometry. The spectral data suggest that in their complexes with Group 12 metal cations, both thiosemicarbazones are neutral and S‐monodentate; and for [Zn(4 EL1)2I2] ( 3 ), [Cd(4 EL1)2Br2] ( 5 ) and [Hg(4 EL1)Cl2]2 ( 7 ) this was confirmed by X‐ray diffractometry. By contrast, in its complexes with CuII and Group 10 metal cations, 4 EL1 is monodeprotonated and S,N‐bidentate, as was confirmed by X‐ray diffractometry for [Ni(4 EL1–H)2] ( 11 ) and [Pd(4 EL1–H)2] ( 12 ).  相似文献   

20.
Acid‐treated g‐C3N4‐Cu2O was prepared by hydrothermal reduction followed by high temperature calcination and acid exfoliation. The structures and properties of as‐synthesized samples were characterized using a range of techniques, such as X‐ray photoelectron spectroscopy, scanning electron microscopy, Photoluminescence Spectroscopy and the Brunauer–Emmett–Teller (BET) theory. The photocatalytic activity was evaluated by measuring the photodegradation of methyl orange under visible‐light irradiation. Based on the results of TEM, XPS, EPR and other techniques, it was verified that a heterojunction was formed. The acid treatment process can increase the specific surface area to form abundant heterojunction interfaces as channels for photo‐generated carrier separation, thereby enhancing its light utilization and quantum efficiency. Results indicate that acid‐treated g‐C3N4‐Cu2O possesses a large specific surface area, which provides plentiful activated sites for heterojunctions to form; in addition, it showed a high visible light effect and the minimum charge‐transfer resistance. Furthermore, the g‐C3N4‐Cu2O material exhibits high levels of effectiveness and stability. Electron paramagnetic resonance and a series of radical trapping experiments demonstrate that the holes and ?O2? could be the main active species in methyl orange photodegradation. This work could provide new insights into the fabrication of composite materials as high‐performance photocatalysts, and facilitate their application in addressing environmental protection issues.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号