胺和水插层磷酸锰仿生模拟氢键网络用于电催化水氧化

Asymmetric manganese cluster, the active center of photosystem II (PSII) in nature, is hydrogen-bonded to surrounding amino acid residues and water molecules. This phenomenon is of great inspiration significance for developing and studying artificial Mn-based oxygen evolution reaction (OER) catalysts. Herein, we prepared manganese phosphate nanosheets through intercalation of ethylenediamine ions and water molecules ((EDAI)(H₂O)MnPi) using a simple co-precipitation method. (EDAI)(H₂O)MnPi is also hydrogen-bonded to interlayer ethylenediamine ions and water molecules, forming a hydrogen-bonding network. The morphology of the (EDAI)(H₂O)MnPi sample was characterized by scanning electron microscopy (SEM) and transmission electron microscopy. The thickness of (EDAI)(H₂O)MnPi was characterized by atomic force microscopy. The composition and structure of (EDAI)(H₂O)MnPi were characterized by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy. For control studies, manganese phosphate (EDAI)MnPi and (H₂O)MnPi samples were also synthesized. The structure and morphology of (EDAI)MnPi and (H₂O)MnPi samples were characterized by XRD and SEM. The difference between (EDAI)(H₂O)MnPi, (EDAI)MnPi, and (H₂O)MnPi were further characterized by thermal gravimetric analysis and derivative thermogravimetric analysis. Electrocatalytic properties of the (EDAI)(H₂O)MnPi, (EDAI)MnPi, and (H₂O)MnPi for OER were studied in 0.05 mol∙L⁻¹ pH = 7 phosphate buffered saline solution, through linear sweep voltammetry, electrochemical impedance spectroscopy, and controlled potential electrolysis (CPE) test. The electrochemical surface area (ECSA) analyses of (EDAI)(H₂O)MnPi, (EDAI)MnPi, and (H₂O)MnPi samples were recorded by charging currents in the non-Faradaic potential region at different scan rates. Considering the different ECSAs of different materials, the water oxidation activities of three materials were normalized by ECSA. Compared with counterparts of (EDAI)MnPi (610 mV) and (H₂O)MnPi (580 mV), manganese phosphate nanosheets (EDAI)(H₂O)MnPi exhibited a lower overpotential of 520 mV when driving a current density of 1 mA∙cm⁻² in neutral conditions. The CPE experiment revealed that (EDAI)(H₂O)MnPi remained active for at least 10 h. Manganese phosphate nanosheets containing a rich, extensive, and continuous hydrogen bond network exhibited improved OER performance in neutral conditions. The hydrogen-bonding network in manganese phosphate nanosheets has similar functions to the hydrogen-bonding network in PSII, which could accelerate the transfer rate of protons and facilitate electrocatalytic water oxidation. This study may provide guidance for the design of water oxidation catalysts with rich hydrogen bond network.     

超细二氧化硅粉体的制备

超细二氧化硅粉体的制备李中军＊刘长让王雪清ａ赵秦生（郑州大学化学化工学院，物理系ａ郑州４５００５２）（中南工业大学长沙）关键词溶胶－凝胶法，ＳｉＯ２超细粉，粉体制备１９９７－０９－２３收稿，１９９８－０３－０２修回溶胶－凝胶工艺是液相法制备超细ＳｉＯ...     

固体超酸POSA催化醇脱水制烯

固体超酸由于其优良的催化性能,近年来倍受重视。其中以全氟骨架的磺酸树脂Nafion H应用最广。POSA(全氟辛基磺酸,C_8F_(17)SO_3H)也是一种化学性质稳定、易回收的固体超酸,具有与Nafion H相似的氟碳链磺酸结构。     

Acid Sensitive Polymeric Micelles Combining Folate and Bioreducible Conjugate for Specific Intracellular siRNA Delivery

An efficiently siRNA transporting nanocarrier still remains to be developed. In this study, utilizing the dual stimulus of acid tumor extracellular environment and redox effect of glutathione in the cytosol, a new siRNA transporting system combining triple effects of folate targeting, acid sensitive polymer micelles, and bio‐reducible disulfide bond linked siRNA‐cell penetrating peptides (CPPs) conjugate is developed to suppress c‐myc gene expression of breast cancer (MCF‐7 cells) both in vitro and in vivo. Subsequent research demonstrates that the vesicle has particle size of about 100 nm and siRNA entrapment efficiency of approximately 80%. In vitro studies verified over 90% of encapsulated siRNA‐CPPs can be released and the vesicle shows higher cellular uptake in response to the tumorous zone. Determination of gene expression at both mRNA and protein levels indicates the constructed vesicle exhibited enhanced cancer cell apoptosis and improved therapeutic efficacy in vitro and in vivo.

     

Synthesis,spectroscopic and structural characterization of diphenyltin(IV) complexes of acetone Schiff bases of S-alkyldithiocarbazates

New diphenyltin(IV) complexes of empirical formula, [Sn(C₆H₅)₂(NS)Cl] (NS = anionic forms of the acetone Schiff bases of S-methyl or S-benzyldithiocarbazate) have been prepared and characterized by IR, NMR and Mössbauer spectroscopic techniques. The crystal and molecular structures of the acetone Schiff bases of S-methyldithiocarbazate (Hacsme) and S-benzyldithiocarbazate (Hacsbz) and their tin(IV) complexes have been determined by X-ray diffraction. In the solid state, both the Schiff bases exist in their thioketo tautomeric forms with the azomethine nitrogen atom trans to the thione sulfur atom but in the tin(IV) complexes they are present in their deprotonated ene-thiolate forms being coordinated to the tin atom as bidentate chelating agents via the azomethine nitrogen and thiolate sulfur atoms. The tin atom adopts a five-coordinate, approximately trigonal bipyramidal geometry, with the thiolate sulfur atom of the Schiff base and the two phenyl groups occupying the equatorial positions. The azomethine nitrogen atom and the chlorine ligand occupy axial positions. The distortion from a regular trigonal bipyramidal or a square-pyramidal geometry is attributed to the restricted bite sizes of the five-membered chelate rings.     

Synthesis and solid-state spectroscopic investigation of some novel diorganotin(IV) complexes of tetraazamacrocyclic ligands

The tetradendate macrocyclic ligands, [H₂L-1 = 5,12-dioxa-7,14-dimethyl-1,4,8,11-tetraazacyclotetradeca-1,8-diene] and [H₂L-2 = 6,14-dioxa-8,16-dimethyl-1,5,9,13-tetraazacyclohexadeca-1,9-diene] have been prepared by the condensation reaction of 1,2-diaminoethane and 1,3-diaminopropane, respectively, with ethyl acetoacetate in methanol at room temperature. The diorganotin(IV) complexes of general formula [R₂Sn(L-1)/R₂Sn(L-2)] (R = Me, n-Bu and Ph) have been synthesized by template condensation reaction of 1,2-diaminoethane or 1,3-diaminopropane and ethyl acetoacetate with R₂SnCl₂ (R = Me or Ph) or n-Bu₂SnO in 2:2:1 molar ratio at ambient temperature (35 ± 2 °C) in methanol. The solid-state characterization of resulting complexes have been carried out by elemental analysis, IR, recently developed DART-mass, solid-state ¹³C NMR, ^119mSn Mössbauer spectroscopic studies. These studies suggest that in all of the studied complexes, the macrocyclic ligands act as tetradentate coordinating through four nitrogen atoms giving a skew-trapezoidal bipyramidal environment around tin center. Since, the studied diorganotin(IV) macrocyclic complexes are insoluble in common organic solvents, hence good crystals could not be grown for single crystal X-ray crystallographic studies. Thermal studies of all of the studied complexes have also been carried out in the temperature range 0-1000 °C using TG, DTG and DTA techniques. The end product of pyrolysis is SnO₂ confirmed by XRD analysis.     

Co掺杂SAPO-5分子筛制备及其催化氧气氧化环己烷反应性能(英文)

环己醇和环己酮(KA油)是制备尼龙所需材料己二酸和己内酰胺的重要中间体,也可用作油漆、农药和染料等的溶剂以及染色和褪光丝的均化剂等.工业上制取KA油的方法主要为苯酚加氢法、环己烯水合法和环己烷氧化法,其中环己烷氧化法最为普遍,是非常重要的工业过程.为获得适宜的KA油选择性,工业上普遍采用Co盐为催化剂,将环己烷氧化单程转化率控制在5.0%以下,从而使得产物选择性达到70%以上.该环己烷氧化制KA油过程不仅生产效率较低,而且所用均相催化剂因分离困难而不能重复使用.因此,当前关于环己烷氧化反应催化剂的研究均是围绕多相催化剂进行.氧气选择性氧化环己烷反应因具有更高的原子经济性而逐渐成为环己烷氧化法制KA油研究中最具挑战性的课题.该反应是自由基机理,而Co~(2+),Cr~(3+),Mn~(2+)和Ce~(2+)等金属离子可以促进自由基链反应,因此含有这些金属的多相催化剂被广泛用于该反应.另一方面,AlPO-n系列分子筛由于具有特殊的孔结构和一定的表面酸性,在催化反应中显示出较大的应用潜力.如果进行杂原子掺杂,通过改变分子筛骨架的电荷平衡,可以有效提高其表面酸性.例如磷酸硅铝分子筛(SAPO-5)具有中等强度的酸性和良好的择形性,因而作为固体酸催化剂广泛用于乙醇脱水、甲醇制烯烃、丙烯聚合和苯乙烯环氧化等反应,表现出较高的选择性和良好的稳定性.本文以传统均相Co盐催化剂的多相化为出发点,制备了Co掺杂SAPO-5与分子筛催化剂(Co-SAPO-5),考察了Co掺杂量对催化剂结构、表面性质以及氧气选择性氧化环己烷反应性能的影响.结果表明,一部分Co进入分子筛骨架,同时有少量Co以氧化钻形式高度分散在SAPO-5表面.Co掺杂对SAOP-5催化剂比表面积没有显著影响,但可使其孔体积减小.相反,Co掺杂可以提高SAOP-5分子筛表面B酸性位数量和总酸量.活性测试结果表明,环己烷转化率随着Co-SAPO-5催化剂中Co含量的增加而增加,但KA油选择性在转化率高于6.3%时急剧下降.还考察了反应温度、反应时间、初始氧气压力和催化剂用量对Co-SAPO-5分子筛催化剂性能的影响,得到了最优反应条件.以Co-SAPO-5-0.2(Co/Si摩尔比为0.2)分子筛为催化剂时,KA油总收率最高可达7.8%.另外,Co-SAPO-5催化剂在环己烷氧化反应中显示出很好的稳定性,Co-SAPO-5-0.2催化剂套用6次后活性几乎没有变化.     

Sulfobutylated Lignosulfonate with Ultrahigh Sulfonation Degree and Its Dispersion Property in Low-Rank Coal-Water Slurry

Using a simple method, we developed a new family of alkyl sulfonic acid modified lignosulfonate (ASLSs) with simultaneously improved sulfonation degrees and molecular weights via one step. Direct sulfonation occurred on both phenolic and alcoholic hydroxyl groups of alkali lignin raw material with 1,4-butylenesulfone used as sulfonation agent. A sulfonation degree of 3.86 mmol/g had been achieved which presents as one of the highest sulfonation degrees among those of reported LSs, to date. ¹H-NMR and Fourier transform infrared spectroscopy measurements confirmed the efficient sulfonation. Furthermore, the dispersion properties were investigated in low-rank coal-water slurry (CWS). ASLS3 showed better viscosity-reduction effect than naphthalene sulfonate formaldehyde condensate (FDN) in CWS with dosages from 0.6% to 1.0 wt%. ASLS3 had the similar sulfonation degree with FDN; however, the large steric hindrance, soft long alkyl chain-C₄H₈-SO₃H, and their efficient anchoring effect of ASLSs contributed to their improved dispersion properties.     

A delicately designed functional binder enabling in situ construction of 3D cross-linking robust network for high-performance Si/graphite composite anode

The silicon (Si)-based anodes suffer from large volume expansion in the lithiation process. Aiming at improving the cycling stability of a Si/graphite composite anode processed by chemical vapor deposition (CVD) method, a functional aqueous binder was delicately designed and synthesized via an aqueous copolymerization of lithium acrylate and vinyl triethoxy silane (VTEO). The PAA-VTEO binder can in situ react with the silanol groups on the surface of Si nanoparticles to form a robust 3D cross-linked network. The resulting extremely high modulus and hardness of this integrated 3D network structure effectively restrained the volume expansion effect and significantly enhanced the electrochemical cycling stability of the CVD-Si@graphite composite anode. This work will provide new perspectives in designing functional binder for Si-based anodes.