Electrochemical reduction of 5-halo-5-nitro-1,3-dioxanes and 2-halo-2-nitro-1,3-propanediols

The character of the first stage of reduction of 5-X-5-nitro-1,3-dioxanes 1—10 and 2-X-2-nitro-1,3-propanediols 11 and 12 is independent of the nature of halogen (X = Br, Cl) and substituents in position 2 of the dioxane cycle. The transfer of two electrons to a molecule of compound 1—12 is accompanied by the anionoid elimination of halogen and formation of the anion of nitronic acid. The high mobility of halogen is mainly due to the acceptor nitro group capable of further transformations in the -position to halogen. The direction of further reduction involving the electron transfer to electrochemically active groups in the aromatic fragment of the molecule is determined by the nature of these groups. Chloro-, bromo-, and iodophenyl-substituted derivatives 4, 5, and 8—10 are reduced as typical halobenzenes. In the case of nitrophenyl-substituted compounds 3 and 7, the dioxane cycle opens to form dianions of p- and m-nitrobenzaldehydes along with the reduction of the nitroso group through the stages of formation of the radical anion and radical anion of the nitroso group. The radical anions of the nitro and nitroso derivatives were identified by ESR.     

Synthetic Ditopic Receptors

A small, but emerging field of topical interest in supramolecularchemistry is ion-pair recognition, in which a host simultaneously binds both cationicand anionic guests. Details of these receptors, which combine, for example, crownethers and calixarenes for cation complexation, with Lewis acid centers, pyrroles, amidesor urea groups for anion recognition, will be discussed. The predicate of this approach,successfully achieved in certain instances, is that the binding of one guest ion caninduce electrostatic and conformational changes in the host, thereby enhancing thecomplexation of the counter ion.     

水滑石层间碘酸根离子的还原性机理研究

通过X射线衍射（XRD）和傅里叶变换红外（FTIR）光谱仪表征发现,经水合肼（N₂H₄·H₂O）和亚硫酸钠（Na₂SO₃）两种还原剂处理碘酸根插层水滑石的产物分别为碘离子插层的水滑石（ZnAl-ILDHs）和硫酸根离子插层水滑石（ZnAl-SO₄LDHs）。进一步研究表明,N₂H₄·H₂O和水滑石的反应为D₇模型的核外层扩散反应,N₂H₄·H₂O在水滑石微球界面和IO₃^-发生反应。而Na₂SO₃则先进入了水滑石层间,然后与层间的IO₃^-反应,其模型符合D₁₁动力学模型。     

Liquid-to-Solid Phase Transitions of Imidazolium-Based Zwitterionic Polymers Induced by Hofmeister Anions

In this study, we compared the responses of two different types of zwitterionic polymers (ZPs), polyvinylimidzole sulfobetaine (poly(SBVI)) and polymethacrylate sulfobetaine (poly(SBMA)) to Hofmeister anions. Although the anions of the two ZPs were the same as the sulfonate anions and only the types of their cations were different from each other, the aggregation behavior of each in the salt aqueous solution was remarkably different. Consequently, poly(SBVI) exhibited both salting-in and salting-out effects depending on the type and concentration of salt, while poly(SBMA) only exhibited the anti-polyelectrolyte effect. The results of this study provide a deeper understanding of the behavior of zwitterionic polymers in salt solutions and will greatly expand their applications.     

有机溶剂对一些无机阴离子色谱的影响

本文对常见的有机溶剂如乙睛、甲醇和乙醇对无机阴离子色谱的保留时间、峰高和半峰宽、峰形和各峰之间的分离度影响进行了研究，发现随着有机溶剂的加入，对离子半径较大，疏水性较强的阴离子，有缩短保留时间的作用，而对离子半径较小，亲水性较强的离子反而增加了保留时间，并对这一现象进行了机理探讨.     

Cations and Anions of Dibenzo[a,e]pentalene and Reduction of a Dibenzo[a,e]pentalenophane

Dibenzo[a,e]pentalene (DBP) is a non-alternant conjugated hydrocarbon with antiaromatic character and ambipolar electrochemical behavior. Upon both reduction and oxidation, it becomes aromatic. We herein study the chemical oxidation and reduction of a planar DBP derivative and a bent DBP-phane. The molecular structures of its planar dication, cation radical and anion radical in the solid state demonstrate the gained aromaticity through bond length equalization, which is supported by nucleus independent chemical shift-calculations. EPR spectra on the cation radical confirm the spin delocalization over the DBP framework. A similar delocalization was not possible in the reduced bent DBP-phane, which stabilized itself by proton abstraction from a solvent molecule upon reduction. This is the first report on structures of a DBP cation radical and dication in the solid state and of a reduced bent DBP derivative. Our study provides valuable insight into the charged species of DBP for its application as semiconductor.     

以苯硒酚为配体的四核银族合物[Me2N]2[Ag4（SePh）6]·CH3OH的合成与晶体结构

合成了以苯硒酚为配体的四核银族合物[Me2N]2[Ag4(SePh)6]·CH3OH,并用X射线单晶衍射法测定了其晶体结构。簇阴离子的核心Ag4Se6是由4个Ag原子组成的四面体内接于6个Se原子组成的变形八面体中,形成了类金刚烷型结构。     

2-羟基-1-萘甲醛缩N-氨基-N′-苯甲酰基硫脲的合成及其阴离子识别性能

2-羟基-1-萘甲醛与水合肼缩合制得2-羟基-1-萘甲醛腙(2);2与硫氰酸铵和苯甲酰氯反应合成了2-羟基-1-萘甲醛缩N-氨基-N′-苯甲酰基硫脲(1),其结构经1H NMR,IR和MS表征。通过UV检测研究了1(DMSO溶液)对8种阴离子的识别作用。当1的DMSO溶液中存在F-,AcO-或H2PO4-时,颜色均由无色变为黄色,同时UV谱图发生显著变化;而加入C l-,B r-,I-,NO3-或HSO4-时,颜色及其UV谱图均无明显变化。结果表明1在DMSO溶液中对F-,AcO-或H2PO4-具有识别作用。     

A Porous and Stable Porphyrin Metal‐Organic Framework as an Efficient Catalyst towards Visible‐Light‐Mediated Aerobic Cross‐Dehydrogenative‐Coupling Reactions

Porphyrin metal‐organic frameworks (PMOFs) are emerging as heterogeneous photocatalysts owing to the well‐designed frameworks incorporated with powerful light‐harvesting porphyrin chromophores. The porous and stable framework Ir?PCN‐224 (which is also denoted as Ir?PMOF‐1), which has been prepared by the self‐assembly of Ir(TCPP)Cl (TCPP=tetrakis(4‐carboxyphenyl)porphyrin) and ZrCl₄, is reported herein to be efficient for the aerobic cross‐dehydrogenative carbon?phosphorus coupling reaction, giving rise to a high turn‐over number (TON) of up to 17200 under visible light irradiation (λ≥420 nm). Electron paramagnetic resonance (EPR) experiments disclose that the active species might be the superoxide radical anion (O₂^.?). Additionally, the intermediate imine cation has been detected by high‐resolution mass spectrometry (HRMS).     

Direct Atomic Absorption Spectrophotometric Analysis of Anion Complexes of Platinum and Gold After their Concentration and Separation from Aqueous Solutions by Anion Exchange Chromatography

Abstract

A strongly basic anion exchange chromatography column (Dowex 2X-8) is utilized for the concentration and separation of platinum and gold anion complexes from aqueous solutions at pH 6. Atomic absorption spectrophotometry has shown to be a very sensitive and selective detection system for the determination of the metallic species. When the column effluent is fed directly to the nebulizer of the atomic absorption instrument detection limits, using a 10-ml sample, are 0.4 μg for Pt and 0.03 μg for Au. These detection limits can be proportionately improved by passing larger sample volumes through the column. A linear relationship between signal and concentration is readily achieved using the procedure.