Impact of Magnesium(II) on Beryllium Fluorides in Solutions Studied by 19F NMR Spectroscopy

Beryllium fluorides are widely used in protein phosphorylation studies to get stable transition state analogs or near attack conformers, which has attracted much attention. BeF₃^? is one of the optimal phosphoryl (PO₃^?) analogs for its identical geometry and charge, and Mg²⁺ naturally participates in the phosphoryl binding in biological systems. In solutions, BeF₃^? coexists with other beryllium fluorides (BeF₄^2?, BeF₂ and BeF⁺) and magnesium fluorides, and there are equilibriums between these species. In this article, ¹⁹F NMR spectroscopy was applied to the investigation of the impact of magnesium(II) on beryllium fluorides. It has been found that when Mg²⁺ was introduced into the solutions, the chemical shifts, the intensities and the line widths of ¹⁹F signals of various beryllium fluoride complexes were changed. After ionic strength correction, these effects were remarkable only for BeF₄^2? and BeF₃^?, especially BeF₄^2?, when the concentration of the fluoride ion is relatively low. Mechanism of the effects is proposed which involves ion pair formation between Mg²⁺ and beryllium fluorides.     

A pyridoxal-based chemosensor for visual detection of copper ion and its application in bioimaging

A pyridoxal-based chemosensor was synthesized by reacting hydrazine hydrate and pyridoxal hydrochloride in ethanol and characterized by NMR and ESI-MS.The optical properties of the compound were investigated in a methanol:HEPES solution.The compound displayed selectivity for Cu2+,as evidenced by a colorless to yellow color change,which was characterized using UV–vis spectroscopy.The fluorescence of the compound can be quenched only by Cu2+,accompanying by a color change from blue to colorless.Furthermore,it can be used in bioimaging.     

Electrospun CuFe2O4 nanotubes as anodes for high-performance lithium-ion batteries

Herein,we report on the synthesis and lithium storage properties of electrospun one-dimensional(1D) CuFe_2O_4 nanomaterials.1D CuFe_2O_4nanotubes and nanorods were fabricated by a single spinneret electrospinning method followed by thermal decomposition for removal of polymers from the precursor fibers.The as-prepared CuFe_2O_4 nanotubes with wall thickness of ~50 nm presented diameters of ~150 nm and lengths up to several millimeters.It was found that phase separation between the electrospun composite materials occured during the electrospinning process,while the as-spun precursor nanofibers composed of polyacrylonitrile(PAN),polyvinylpyrrolidone(PVP) and metal salts might possess a core-shell structure(PAN as the core and PVP/metal salts composite as the shell) and then transformed to a hollow structure after calcination.Moreover,as a demonstration of the functional properties of the 1D nanostructure.CuFe_2O_4 nanotubes and nanorods were investigated as anodes for lithium ion batteries(LIBs).It was demonstrated that CuFe_2O_4 nanotubes not only delivered a high reversible capacity of ~816 mAh·g~(-1) at a current density of 200 mA·g~(-1)over 50 cycles,but also showed superior rate capability with respect to counterpart nanorods.Probably,the enhanced electrochemical performance can be attributed to its high specific surface areas as well as the unique hollow structure.     

XMgO·YMg(OH)_2吸附剂除氟机理及其净化水的水质研究

研究了XMg O·YMg(OH)2对水中氟离子的吸附性能,考察了吸附时间、吸附剂用量、含氟水p H值、温度、含氟水初始浓度等因素对吸附的影响。实验结果表明,在较宽的p H(3.4~8.4)值和水温(22~51℃)范围内,XMg O·YMg(OH)2对水中氟离子具有极强的吸附能力,室温下0.4g XMg O·YMg(OH)2可将100m L浓度为30mg F-1·L-1含氟水处理为符合含氟标准的饮用水。氟离子在XMg O·YMg(OH)2上的吸附速率较大,30min内基本达到吸附平衡,吸附平衡符合Langmuir方程,在50min内达到饱和吸附,室温下饱和吸附量为13.46mg·g-1。净化水呈微碱性,含有5.68~15.07mg·L-1Mg2+,有益于人体健康。吸附饱和后的XMg O·YMg(OH)2经焙烧再生,除氟率可达81%。     

Syntheses,Crystal Structures,and Properties of a New Lead(Ⅱ) Complex Involving Holo-and Hemidirected Coordination Spheres with 3,5,6-Tris(2-pyridyl)-1,2,4-triazine Ligand

[Pb(TPT)(μ-I)2PbI2(μ-I)2Pb(TPT)] 1(TPT is the abbreviation of 3,5,6-tris(2-pyridyl)-1,2,4-triazine ligand) has been synthesized and characterized by elemental analysis, IR, 1HNMR spectroscopy and studied by thermal and electrochemical properties as well as X-ray crystallography. The single-crystal X-ray data show two different kinds of Pb2+ ions in 1 with coordination numbers of six, Pb1 = PbI6, and five, Pb2 = PbN3I2, with holodirected and hemidirected coordination spheres, respectively. The supramolecular features in 1 are negotiated through the weak but directional Pb···I, C–H···N and C–H···I interactions and aromatic π-π stacking interactions.     

聚合物锂离子电池界面相容性的研究进展

聚合物锂离子电池作为储能装置在电子产品中具有广泛的应用前景。电极/聚合物电解质(E/P)界面相容性是影响聚合物锂离子电池电导率、安全性、机械性能的重要影响因素之一。研究E/P界面的电化学反应及形成机理,是解决相容性问题的关键。本文综述了近年来有关聚合物锂离子电池E/P界面相容性及相关研究技术的进展,并对聚合物锂离子电池界面相容性的相关研究进行了展望。     

用基于苯并噻二唑衍生物的比率荧光化学传感器检测氟离子

研制了一种用于灵敏、快速地检测溶液中的氟离子的基于苯并噻二唑衍生物的荧光传感器.4,7-二溴-2,1,3-苯并噻二唑与三甲基硅基乙炔通过Sonogashira偶联反应得到二取代的三甲基硅基乙炔苯并噻二唑;将该化合物用于检测氟离子,分析了检测灵敏度和选择性.结果表明,在乙腈和水(V/V=9∶1)混合溶液中,合成的苯并噻二唑衍生物的最大发射波长峰值为455nm(激发波长为376nm);就所测试的F-,Cl-,Br-,I-,ClO4-,AcO-,NO3-,H2PO3-,CN-和HSO4-等阴离子而言,仅F-可以脱除三甲基硅保护基使得该化合物荧光最大发射波长蓝移至435nm,荧光强度降低60%,且最低检测限可达4.5×10-8 mol/L.因此,二取代的三甲基硅基乙炔苯并噻二唑应用于氟离子检测具有很好的灵敏度和选择性.     

Metal–Organic Framework Membrane Nanopores as Biomimetic Photoresponsive Ion Channels and Photodriven Ion Pumps

Biological ion channels and ion pumps with sub-nanometer sizes modulate ion transport in response to external stimuli. Realizing such functions with sub-nanometer solid-state nanopores has been an important topic with wide practical applications. Herein, we demonstrate a biomimetic photoresponsive ion channel and photodriven ion pump using a porphyrin-based metal–organic framework membrane with pore sizes comparable to hydrated ions. We show that the molecular-size pores enable precise and robust optoelectronic ion transport modulation in a broad range of concentrations, unparalleled with conventional solid-state nanopores. Upon decoration with platinum nanoparticles to form a Schottky barrier photodiode, photovoltage across the membrane is generated with “uphill” ion transport from low concentration to high concentration. These results may spark applications in energy conversion, ion sieving, and artificial photosynthesis.     

Correlating Glycoforms of DC-SIGN with Stability Using a Combination of Enzymatic Digestion and Ion Mobility Mass Spectrometry

The immune scavenger protein DC-SIGN interacts with glycosylated proteins and has a putative role in facilitating viral infection. How these recognition events take place with different viruses is not clear and the effects of glycosylation on the folding and stability of DC-SIGN have not been reported. Herein, we report the development and application of a mass-spectrometry-based approach to both uncover and characterise the effects of O-glycans on the stability of DC-SIGN. We first quantify the Core 1 and 2 O-glycan structures on the carbohydrate recognition and extracellular domains of the protein using sequential exoglycosidase sequencing. Using ion mobility mass spectrometry, we show how specific O-glycans, and/or single monosaccharide substitutions, alter both the overall collision cross section and the gas-phase stability of the DC-SIGN isoforms. We find that rather than the mass or length of glycoprotein modifications, the stability of DC-SIGN is better correlated with the number of glycosylation sites.     

Tailoring A Poly(ether sulfone) Bipolar Membrane: Osmotic-Energy Generator with High Power Density

Osmotic energy, obtained through different concentrations of salt solutions, is recognized as a form of a sustainable energy source. In the past years, membranes derived from asymmetric aromatic compounds have attracted attention because of their low cost and high performance in osmotic energy conversion. The membrane formation process, charging state, functional groups, membrane thickness, and the ion-exchange capacity of the membrane could affect the power generation performance. Among asymmetric membranes, a bipolar membrane could largely promote the ion transport. Here, two polymers with the same poly(ether sulfone) main chain but opposite charges were synthesized to prepare bipolar membranes by a nonsolvent-induced phase separation (NIPS) and spin-coating (SC) method. The maximum power density of the bipolar membrane reaches about 6.2 W m⁻² under a 50-fold salinity gradient, and this result can serve as a reference for the design of bipolar membranes for osmotic energy conversion systems.