锂离子电池电解液成膜添加剂乙烯基亚硫酸乙烯酯的电化学行为

研究了具有不饱和双键和亚硫酸酯双官能团的乙烯基亚硫酸乙烯酯(VES)作为锂离子电池电解液成膜添加剂对中间相碳微球(CMS)和LiFePO4电极电化学性能的影响. 结果表明: 在1 mol/L LiClO4/PC电解液体系中, 少量的VES (5%)能够在电化学过程中先于PC在CMS表面还原, 形成稳定的SEI膜, 明显抑制PC和溶剂化锂离子共嵌入石墨层间, 改善了电池的循环性能. 此外, 电解液1 mol/L LiClO4/PC＋5%VES (V∶V)在LiFePO4电极中展现出良好的电化学稳定性.     

Heme Fe?SO2− intermediates in sulfite reduction: Contrasts with Fe?OO2− species from oxygen–oxygen bond activating systems

Sulfite reductase (SiR) catalyzes a six electron and six proton reduction of sulfite to sulfide. Similarly to the cytochrome P450 (cytP450) family, the active site in SiR contains a (partially reduced) heme bound axially to a cysteinate ligand—though with an extra Fe₄S₄ cluster. Fe(III) SO²⁻, Fe(III) SOH⁻, and Fe(III) SO(H₂) intermediates have been proposed for the catalytic cycle of SiR, leading to a formally Fe(V)S species—akin to the widely accepted reaction mechanism in cytP450. Here, density functional theory (DFT) data is reported for of such FeSO(H₂) intermediates. The Fe(III) SO²⁻ models display relatively high energies for homolytic bond breaking compared to their isomeric oxygen‐bound Fe(III) OS²⁻ models, and thus offer a better alternative in terms of avoiding radical side products able to induce enzyme suicide. This could be due to the fact that the (iron‐bound) sulfur is more active from a redox standpoint compared to oxygen, thus permitting the departing oxygen to maintain a redox‐inert state. Di‐protonation of the oxygen is computed to lead to a compound I type Fe(IV)S coupled to a porphyrin radical anion—consistent with an intermediate previously observed by x‐ray crystallography.     

Crystal structure of a bulky cyclic sulfite

The structure of the cyclic sulfite derived from the reaction of thionyl chloride withendo-8-hydroxy-exo-8-(endo-8-hydroxypentacyclo[5.4.0.0.^2,6.0^3,10.0^5,9]undec-exo-8-yl)pentacyclo-[5.4.0.0.^2,6.0^3,10.0^5,9]undecane is reported. All bond lengths and angles are consistent with the strained cage geometry. A static disorder of the terminal oxygen was found to be present.     

一种SO2固定及用于制备BaSO3或BaSO4的方法

在常温常压下,由乙二胺（EDA）和乙二醇及其衍生物（EGs）组成的混合体系可捕集SO₂并转化为一种SO₂储集材料（SO₂SM）。EDA+EGs体系呈现了强的捕集性能（0.364~0.662 g_SO2·gabsorbent^-1）。FTIR,XPS和XRD结果确证了SO₂SM为一种烷基亚硫酸盐。以EG-SO₂SM为原料制备具有多种形貌的BaSO₃或BaSO₄,在此过程中,EG-SO₂SM不仅提供了原材料,而且可以释放EDA和EG用作表面活性剂,调控晶体的结晶化过程。     

First observation of equilibrium polymerization of cyclic sulfite

Cationic polymerization of a seven-membered cyclic sulfite ( 7CS ) was carried out with methyl trifluoromethanesulfonate as a catalyst in chlorobenzene. The final conversions of 7CS were 22, 41, 52, and 60% in the polymerizations at 25°C with the initial monomer concentrations of 3, 4, 5, and 6M, respectively. The calculated monomer concentration at equilibrium was evaluated as 2.4M in any case. The conversion of 7CS decreased as the polymerization temperature rose. These results support the fact that this polymerization is an equilibrium one. ΔH⁰ and ΔS⁰ in the polymerization were evaliuated as −0.765 kcal/mol and −4.18 cal/mol by Dainton's equation, respectively. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3235–3240, 1997     

电镀法制备微型金柱腔表面质量控制

为了提高金柱腔表面质量,借助扫描电子显微镜及其附带的能量色散谱(EDS),3维视频显微镜(SEM)等现代微观形貌观测手段和成分分析手段,通过单因素实验,分析了金柱腔缺陷形貌和组成以及缺陷产生的原因。探索了电流密度、金属杂质、有机污染物、预镀工艺及基底材质对镀层质量的影响,并对其作用机理进行了探讨。实验结果表明:对麻点和节瘤等缺陷抑制作用明显的工艺参数为,金质量浓度13~22 g/L时,电流密度的最佳范围为2.4~3.2 mA/cm2;金质量浓度5~13 g/L时,最佳范围为2.0~2.6 mA/cm2;大电流冲击时间不超过1 min;镀液无有机杂质污染;芯轴无钝化。     

Porous Capsules with a Large Number of Active Sites: Nucleation/Growth under Confined Conditions

This work deals with the generation of large numbers of active sites and with ensuing nucleation/ growth processes on the inside wall of the cavity of porous nanocapsules of the type (pentagon)₁₂(linker)₃₀≡{(Mo^VI)Mo^VI₅}₁₂{Mo^V₂(ligand)}₃₀. A first example refers to sulfur dioxide capture through displacement of acetate ligands, while the grafted sulfite ligands are able to trap {MoO₃H}⁺ units thereby forming unusual {(O₂SO)₃MoO₃H}^5? assemblies. A second example relates to the generation of open coordination sites through release of carbon dioxide upon mild acidification of a carbonate‐type capsule. When the reaction is performed in the presence of heptamolybdate ions, MoO₄^2? ions enter the cavity where they bind to the inside wall while forming new types of polyoxomolybdate architectures, thereby extending the molybdenum oxide skeleton of the capsule. Parallels can be drawn with Mo‐storage proteins and supported MoO₃ catalysts, making the results relevant to molybdenum biochemistry and to catalysis.     

Synthesis of α,ω‐Diazidoalditol Derivatives via Both bis‐ or tris‐Cyclic Sulfites and Peracetylated α,ω‐Dibromoalditols as Bielectrophilic Intermediates

Abstract

The α,ω‐diazidoalditol derivatives with erythro, threo, xylo, ribo, D‐arabino, D‐manno, and D‐gluco configuration were efficiently synthesized, respectively, from bis‐ or tris‐cyclic sulfite or peracetylated α,ω‐dibromoalditol intermediates. The cyclic sulfite intermediates has the advantage to lead directly to the free α,ω‐diazido‐α,ω‐dideoxyalditols.     

New Procedure for the Synthesis of 2-Alkylbenzimidazoles

Simple, economical, and environmentally friendly method to synthesize 2-alkylbenzimidazoles was developed by modifying the conventional method between o-phenylenediamine and aldehyde.