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911.
The interaction between a water-soluble polymer polyvinylpyrrolidone (PVP) and a gemini surfactant N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-propanediyl-diammonium dibromide (G12-3-12) was investigated by means of NMR in a D2O solution at 298 K. The critical micelle concentration (СMC), critical aggregation concentration (СAC) and adsorption reached the saturated concentration (C2) were confirmed by chemical shift and self-diffusion coefficients, respectively. The results of the relaxation time ratio (TR = T2/T1) of G12-3-12 show that the motion of the ionic head N+–CH3* proton (G6) is seriously restricted, and thus, it can be proved that the cationic head groups are situated in the hydrophilic layer of the micelle. The size of the mixed-aggregates in the G12-3-12/PVP solution is larger than pure G12-3-12 micelles according to self-diffusion coefficients, indicating that the G12-3-12 and PVP has formed mixed micelles, and ionic heads N+–CH3* become more tightly packed in the hydrophilic layer of the micelle shell. On the other hand, strong cross peaks, such as G1-P2, G1-P3, and G2-P3, appear in the 2D nuclear Overhauser enhancement spectroscopy (2D NOESY) spectra of the G12-3-12/PVP system, further indicating that the interaction sites are located between the hydrophobic tail of G12-3-12 and PVP ring. 相似文献
912.
Han Guan-Qun Li Xiao Zhao Xin Dong Bin Hu Wen-Hui Liu Yan-Ru Shang Xiao Chai Yong-Ming Liu Chen-Guang 《Journal of Solid State Electrochemistry》2016,20(10):2907-2912
Journal of Solid State Electrochemistry - ε-MnO2 microspheres have been synthesized using a self-sacrificial template method by annealing MnCO3 microspheres. The transformation process from... 相似文献
913.
The utilization of nickel hydroxide and manganese dioxide solely as high-performance supercapacitive materials is hindered by their low capacitance retention and electrical conductivity. As Ni(OH)2 and MnO2 give a synergistic effect, porous Ni(OH)2-MnO2 nanosheets with a thickness of 9 nm are successfully grown on carbon fiber (CF) via a single-step hydrothermal co-deposition method. Multi-walled carbon nanotubes (CNT) are grafted with maleic anhydride (MA) through plasma-grafted process, followed by thiol-ene reaction to synthesize CNT-MA−S (CMS) to increase their aqueous dispersion behavior. The electrochemical properties of Ni(OH)2-MnO2 are further enhanced by dip-coating CMS on nanosheets. The composition and morphology of CMS and Ni(OH)2-MnO2 nanosheets are characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA), transmission electron microscopy (TEM), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), and Raman spectroscopy. The electrochemical characteristics of fabricated electrodes are analyzed using cyclic voltammetry and chronopotentiometry methods. CF−Ni(OH)2-MnO2/CMS electrode is successfully synthesized without using any binder, exhibited ultrahigh specific capacitance (2049 F g−1 at a current density of 1 A g−1), and excellent capacitance retention (>80 %) at 2 A g−1 charge/discharge rate after 5000 cycles. 相似文献
914.
Fen Su Dr. Juan Zou Xiaokang Lv Fengfei Lu Yijie Long Kun Tang Benpeng Li Prof. Dr. Huifang Chai Prof. Xingxing Wu Prof. Dr. Yonggui Robin Chi 《Angewandte Chemie (International ed. in English)》2023,62(23):e202303388
The development of catalyst-controlled methods for direct functionalization of two distinct C−H bonds represents an appealing approach for C−C formations in synthetic chemistry. Herein, we describe an organocatalytic approach for straightforward acylation of C(sp3)−H bonds employing readily available aldehyde as “acyl source” involving dehydrogenative coupling of aldehydes with ether, amine, or benzylic C(sp3)−H bonds. The developed method affords a broad range of ketones under mild conditions. Mechanistically, simple ortho-cyanoiodobenzene is essential in the oxidative radical N-heterocyclic carbene catalysis to give a ketyl radical and C(sp3) radical through a rarely explored intermolecular hydrogen atom transfer pathway, rendering the acylative C−C formations in high efficiency under a metal- and light-free catalytic conditions. Moreover, the prepared products show promising anti-bacterial activities that shall encourage further investigations on novel agrochemical development. 相似文献
915.
Liangwei Yang Zhenyu Li Linwei He Jiayu Sun Junren Wang Yumin Wang Dr. Ming Li Zibin Zhu Prof. Xing Dai Prof. Shu-Xian Hu Dr. Fuwan Zhai Qian Yang Ye Tao Prof. Zhifang Chai Prof. Shuao Wang Prof. Yaxing Wang 《Angewandte Chemie (International ed. in English)》2023,62(33):e202306465
The development of high-performance X-ray detectors requires scintillators with fast decay time, high light yield, stability, and X-ray absorption capacity, which are difficult to achieve in a single material. Here, we present the first example of a lanthanide chalcogenide of LaCsSiS4 : 1 % Ce3+ that simultaneously integrates multiple desirable properties for an ideal scintillator. LaCsSiS4 : 1 % Ce3+ demonstrates a remarkably low detection limit of 43.13 nGyair s−1 and a high photoluminescence quantum yield of 98.24 %, resulting in a high light yield of 50480±1441 photons/MeV. Notably, LaCsSiS4 : 1 % Ce3+ exhibits a fast decay time of only 29.35±0.16 ns, making it one of the fastest scintillators among all lanthanide-based inorganic scintillators. Furthermore, this material shows robust radiation and moisture resistance, endowing it with suitability for chemical processing under solution conditions. To demonstrate the X-ray imaging capacity of LaCsSiS4 : 1 % Ce3+, we fabricated a flexible X-ray detector that achieved a high spatial resolution of 8.2 lp mm−1. This work highlights the potential of lanthanide chalcogenide as a promising candidate for high-performance scintillators. 相似文献
916.
Hai-Jun Liu Shuo Zhang Prof. Yong-Ming Chai Prof. Bin Dong 《Angewandte Chemie (International ed. in English)》2023,62(48):e202313845
Highly efficient hydrogen evolution reaction (HER) electrocatalyst will determine the mass distributions of hydrogen-powered clean technologies, while still faces grand challenges. In this work, a synergistic ligand modulation plus Co doping strategy is applied to 1T−MoS2 catalyst via CoMo-metal-organic frameworks precursors, boosting the HER catalytic activity and durability of 1T−MoS2. Confirmed by Cs corrected transmission electron microscope and X-ray absorption spectroscopy, the polydentate 1,2-bis(4-pyridyl)ethane ligand can stably link with two-dimensional 1T−MoS2 layers through cobalt sites to expand interlayer spacing of MoS2 (Co−1T−MoS2-bpe), which promotes active site exposure, accelerates water dissociation, and optimizes the adsorption and desorption of H in alkaline HER processes. Theoretical calculations indicate the promotions in the electronic structure of 1T−MoS2 originate in the formation of three-dimensional metal-organic constructs by linking π-conjugated ligand, which weakens the hybridization between Mo-3d and S-2p orbitals, and in turn makes S-2p orbital more suitable for hybridization with H-1s orbital. Therefore, Co−1T−MoS2-bpe exhibits excellent stability and exceedingly low overpotential for alkaline HER (118 mV at 10 mA cm−2). In addition, integrated into an anion-exchange membrane water electrolyzer, Co−1T−MoS2-bpe is much superior to the Pt/C catalyst at the large current densities. This study provides a feasible ligand modulation strategy for designs of two-dimensional catalysts. 相似文献
917.
Jin-Dong Wang Dr. Kong-Qiu Hu Dr. Zhi-Wei Huang Prof. Lei Mei Dr. Ji-Pan Yu Prof. Zhi-Fang Chai Dr. Xin-Peng Wang Prof. Wei-Qun Shi 《欧洲无机化学杂志》2023,26(15):e202300072
The polynuclear metal clusters continually attract wide interest due to their intriguing structures and potential applications in various scientific fields. Here, four actinide clusters have been synthesized by the utilization of multifunctional ligand ferrocenecarboxylic acid (HFcc) and Th4+/U4+ ions by solvent evaporation or solvothermal synthesis strategies in different solvents. Therein, compounds 1 , 2 and 4 feature similar [An6(μ3-O)4(μ3-OH)4]12+ cores, which are further coordinated by 12 Fcc− ligands and different solvent molecules. The U6Fe12 cluster of compound 4 is linked by four free HFcc molecules via multiple hydrogen bonding to form a supramolecular cluster [U6(μ3-O)4(μ3-OH)4(Fcc)12(H2O)4] ⋅ 4HFcc. The cluster core of compound 3 is a μ3-O2− bridged [U3(μ3-O)]10+ unit, which is further coordinated by 10 Fcc− ligands via three kinds of coordination modes. It is worth noting that multifunctional Fcc− ligand not only endows compound 1 a main redox wave at E1/2=0.720 V in CH2Cl2/DMF solution, but also enables it to exhibit aggregation-induced emission (AIE) property. 相似文献
918.
Goldberg R Chai L Perkin S Kampf N Klein J 《Physical chemistry chemical physics : PCCP》2008,10(32):4939-4945
Using a surface force balance, we have measured the normal and shear forces between mica surfaces across aqueous caesium salt solutions (CsNO(3) and CsCl) up to 100 mM concentrations. In contrast to all other alkali metal ions at these concentrations, we find no evidence of hydration repulsion between the mica surfaces on close approach: the surfaces appear to be largely neutralized by condensation of the Cs ions onto the charged lattice sites, and are attracted on approach into adhesive contact. The contact separation at adhesion indicates that the condensed Cs ions protrude by 0.3 +/- 0.2 nm from each surface, an observation supported both by the relatively weak adhesion energies between the surfaces, and the relatively weak frictional yield stress when they are made to slide past each other. These observations show directly that the hydration shells about the Cs(+) ions are removed as the ions condense into the charged surface lattice. This effect is attributed to the low energies-resulting from their large ionic radius-required for dehydration of these ions. 相似文献
919.
A facile and efficient one-pot synthesis of highly substituted thiophenes has been developed and employed for the preparation of a small focused library. Treatment of 1,3-dicarbonyl compounds 1 with CS2 in the presence of K2CO3 in DMF at room temperature, followed by stepwise addition of alkyl bromides 2 and methylene active bromides 3, provided via intramolecular cyclization 2,3,4,5-tetrasubstituted thiophenes 4 in yields of 77-94%. This protocol, combining construction and modification of the thiophene ring, increases the structural diversity of final products from readily available materials. A mechanism for the one-pot synthesis of thiophenes of type 4 has been proposed. A small focused library of thiophenes is prepared using the sequential addition of reagents to achieve unique substitution in the 2 and 5 position of the thiophene ring. 相似文献
920.
A microwave-assisted protocol was developed for the construction of di- and monosubstituted 2-aminoimidazoles. The two-step reaction involves the synthesis of N-(1H-imidazol-2-yl)acetamides from readily available alpha-haloketones and N-acetylguanidine, followed by deacetylation. Significant rate enhancement was observed for both steps of the protocol, and the overall reaction time was shortened to 20 min compared to 48 h of the conventional procedures. A representative set of di- and monosubstituted 2-aminoimidazoles was prepared using commercially available parallel reactors. 相似文献