Interweaving anion templation

A new general interweaving anion templation strategy for the formation of interpenetrated and interlocked architectures is presented. Furthermore, the functional properties of the resulting systems, which have novel anion binding and sensory properties, are discussed.     

基于吡咯的阴离子受体研究进展

识别阴离子的超分子体系作为一个新的研究领域,在传感器、萃取剂、阴离子响应性材料、离子载体及其它领域得到了迅速发展。综述了单吡咯受体、基于二吡咯烯和二吡咯酮的受体以及联吡咯甲烷受体等非环吡咯体系在阴离子识别方面的应用。非环吡咯比环状吡咯化合物更容易合成,因此非环吡咯衍生物将作为构筑单元被广泛用于创造更复杂的阴离子受体。     

Microheterogeneity of anion exchange membranes

Anion exchange membranes (ferricyanide ion type) prepared by the “paste method” were treated with an aqueous solution of hydrogen peroxide, and the resultant microporous membranes had no ion exchange capacity but water permeability. By measuring the water permeability of the membranes and observing the electron microphotographs of the membrane surfaces, it was elucidated that the anion exchange membranes contained microheterogeneity of colloidal dimension.     

Exchange equilibria on anion resins

Selectivity coefficients, free exchange energies and enthalpies between 5°C and 45°C of different anion resins with functional groups of the amino type were determined for the SO^?₄/Cl^? system in a range of bulk salinities lying between 6 x 10^?3 and 2.4 NThe experimental results showed that the selectivity for the bivalent ion depends strongly on the basicity of the resin, the affinities of the various amino functional groups following the order primary > secondary > tertiary > quaternary. Furthermore, the affinity of every resin for the sulphate ion increases with the dilution of the aqueous phase and with the equilibrium temperature. These results are in full agreement with the theoretical forecasts, and show that in heterovalent exchange processes a fundamental role is played by the phenomena connected with the electrostatic interactions.     

Styrene furfural-based weak-base anion exchanger

A weak-base anion-exchange resin based on Styrene-furfural polymer has been prepared and characterized. A suitable composition to the repeating unit in the polymer has been proposed and supported by experimental evidences.     

From anion receptors to transporters

Cystic fibrosis is the most well-known of a variety of diseases termed channelopathies, in which the regulation of ion transport across cell membranes is so disrupted that the threshold of a pathology is passed. The human toll exacted by these diseases has led a number of research groups, including our own, to create compounds that mediate ion transport across lipid bilayers. In this Account, we discuss three classes of synthetic compounds that were refined to bind and transport anions across lipid bilayer membranes. All of the compounds were originally designed as anion receptors, that is, species that would simply create stable complexes with anions, but were then further developed as transporters. By studying structurally simple systems and varying their properties to change the degree of preorganization, the affinity for anions, or the lipophilicity, we have begun to rationalize why particular anion transport mechanisms (cotransport or antiport processes) occur in particular cases. For example, we have studied the chloride transport properties of receptors based on the closely related structures of isophthalamide and pyridine-2,6-dicarboxamide: the central ring in each case was augmented with pendant methylimidazole groups designed to cotransport H(+) and Cl(-). We observed that the more preorganized pyridine-based receptor was the more efficient transporter, a finding replicated with a series of isophthalamides in which one contained hydroxyl groups designed to preorganize the receptor. This latter class of compound, together with the natural product prodigiosin, can transport bicarbonate (as part of a chloride/bicarbonate antiport process) across lipid bilayer membranes. We have also studied the membrane transport properties of calix[4]pyrroles. Although the parent meso-octamethylcalix[4]pyrrole functions solely as a Cs(+)/Cl(-) cotransporter, other compounds with increased anion affinities can function through an antiport process. One example is octafluoro-meso-octamethylcalix[4]pyrrole; with its electron-withdrawing substituents, it can operate through a chloride/bicarbonate antiport process. Moreover, calix[4]pyrroles with additional hydrogen bond donors can operate through a chloride/nitrate antiport process. Thus, increasing the affinity of the receptor in these cases allows the compound to transport an anion in the absence of a cation. Finally, we have studied the transport properties of simple thioureas and shown that these compounds are highly potent chloride/bicarbonate antiport agents that function at low concentrations. In contrast, the urea analogues are inactive. The higher hydrophobicity (reflected in higher values for the logarithm of the water-octanol partition constant, or log P) and lower polar surface areas of the thiourea compounds compared to their urea analogues may provide a clue to the high potency of these compounds. This observation might serve as a basis for designing future small-molecule transporters.     

Chromic acid removal by anion exchange

The kinetics of dilute chromic acid removal by anion exchange was studied using a batch system. Rate model formulated for total Cr(VI) removal based on film diffusion control was applied. This rate model was shown to adequately fit the experimental rate data. In addition, column experimental runs were performed by using 20-50 mesh anion resin with feed solution containing 0.2 g/L CrO₃. The bed heights of 15, 25 and 35 cm and flow rates ranging from 1.02 cm/s to 2.38 cm/s were employed in the experiments. Linear driving force rate expression based on film diffusion rate control was incorporated in the model equations for simulation of column performance. The kinetic parameter and equilibrium relation in the rate equation were obtained independently either by separate experiments or from data available in the literature. Satisfactory agreements between experimental and calculated breakthrough curves were obtained.     

Porphyrin counter anion in imidazolium-modified graphene-oxide

Imidazolium-modified graphene-oxide hybrid materials have been prepared and characterized by complementary spectroscopic, thermal and microscopy techniques, while the counter anion of the positively charged imidazolium fragment identified by energy dispersive X-ray analysis. Moreover, the counter anion has been exchanged, thus (i) allowing to modulate the wettability of the material (i.e., switchable hydrophilic vs lipophilic counter anion), resulting on switching the dispersibility of the hybrid material from aqueous to organic solvents, based on the nature of the anion, and (ii) introducing an extra functionality, such as a photoactive anionic porphyrin. The latter has allowed the performance of optical and electrochemical studies, which denote that some interaction takes place between the porphyrin counter anion and graphene-oxide. Finally, the energy gap has been calculated from the reduction and oxidation potentials of the hybrid material.     

Synthesis of stereoblock poly(methyl methacrylate) via transformation of isotactic-specific living polymer anion to syndiotactic-specific anion

Polymerization of methyl methacrylate (MMA) by isotactic poly(methyl methacrylate) (PMMA) living anion, prepared with t-C₄H₉MgBr in toluene at ?60°C, was carried out at ?78°C in the presence of trialkylaluminiums (R₃Al; R = CH₃, C₂H₅, and n-C₄H₉) to obtain a stereoblock PMMA, isotactic PMMA-block-syndiotactic PMMA. Among the R₃Als, (CH₃)₃Al gave most effectively the steroblock PMMA with narrow molecular weight distribution. The fraction of rr triad in the syndiotactic PMMA block increased with increase in the ratio of Al/Mg and reached about 76% at a ratio of Al/Mg ≥ 6. The method was also used to prepare stereoblock copolymer comprising isotactic PMMA block and syndiotactic block of butyl methacrylate. Stereocomplex formation and solution viscosity of the stereoblock PMMA were also studied.     

基于吡咯-酰胺混合单元的阴离子受体的研究进展

综述了最近10年来对含有吡咯酰胺混合单元的阴离子受体的研究进展,重点评述了这些受体的阴离子配位性质。这些阴离子受体包括桥联二吡咯柄型二茂铁、基于联吡咯的索烃、附加有离子基团的吡咯酰胺、吡咯-2,5-二甲酰胺和吡咯-2,5-二乙酰胺。     

Comb-shaped diblock copolystyrene for anion exchange membranes

To improve the properties of diblock copolystyrene-based anion exchange membranes (AEMs), a series of AEMs with comb-shaped quaternary ammonium (QA) architecture (QA-PS_m-b-PDVPPA_n-xC where x denotes the number of carbon atoms in different alkyl tail chains and has values of 1, 4, 8, and 10 and C denotes carbon) were designed and synthesized via subsequent quaternization reactions with three different alkyl halogens (methyl iodide and N-alkane bromines (CH₃[CH₂] _x-1Br where x = 4, 8, and 10). Compared with triblock analogues quaternized with methyl iodide in our previous research, QA-PS_m-b-PDVPPA_n-xC (x = 4, 8, and 10) AEMs are more flexible with the introduction of a long alkyl tail chain; this probably impedes crystallization of the rigid polystyrene-based main chain and induces sterically adjustable ionic association. An increase in the pendant alkyl tail chain length generally led to enhanced microphase separation of the obtained AEMs, and this was confirmed using small-angle X-ray scattering and atomic force microscopy. The highest conductivity (25.5 mS cm⁻¹) was observed for QA-PS₁₂₀-b-PDVPPA₈₀-10C (IEC = 1.94 meq g^–1) at 20 °C. Furthermore, the water uptake (<30%) and swelling ratio (<13.1%) of QA-PS_m-b-PDVPPA_n-xC AEMs are less than half of these corresponding values for their triblock counterparts. The QA-PS₁₂₀-b-PDVPPA₈₀-10C membrane retained a maximum stability that was as high as 86.8% of its initial conductivity after a 40-day test (10 M NaOH, 80 °C), and this was probably because of the steric shielding of the cationic domains that were surrounded by the longest alkyl tail chains. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47370.     

制备阴离子聚丙烯酰胺影响因素的研究

采用新型氧化-还原体系,以丙烯酰胺（AM）和丙烯酸（AM为单体共聚得到阴离子聚丙烯酰胺（HPAM）。研究了EDTA用量、反应温度等对HPAM制备的影响。结果表明：EDTA用量、反应温度等直接影响到HPAM的分子量高低与溶解性好坏。用傅立叶红外光谱仪对一定工艺条件下所得产物进行表征,证明可得到分子量高且溶解性能好的HPAM。     

淀粉基阴离子微球的制备

以可溶性淀粉为原料,N’N-亚甲基双丙烯酰胺(MBAA)及环氧氯丙烷(ECH)为交联剂,先在反向悬浮体系中采用两步交联法制备了中性淀粉微球,再用K3P3O9与中性淀粉微球反应制得淀粉基阴离子微球。以微球的平均粒径为指标,利用扫描电镜(SEM)和光透式粒度分析仪对产物进行了表征。结果表明,反应时间为2.5 h,淀粉溶液浓度为15%,油相与水相的体积比为3∶1,MBAA用量为0.4 g,乳化剂用量为1.0 g时,微球平均粒径分布较为均一,粒径在65μm以下的微球占95.5%,球形圆整,表面粗糙多孔,可用作药物载体和吸附剂。     

An anion exchange resin from soybean hulls

Agricultural by‐products are generally poor adsorbents of anions in solution. Therefore, modification of the by‐product could enhance its anion exchange capabilities. The objective of this study was to increase the anion exchange properties of the agricultural by‐product, soybean hulls, by chemical modification. Soybean hulls were quaternized with the quaternizing agent, N‐(3‐chloro‐2‐hydroxypropyl) trimethylammonium chloride, in the presence of a strongly alkaline environment. This modification increased the amount of positive charge on the hulls as evidenced by increased nitrogen content and increased uptake of anions compared with the unmodified hulls. A method to optimize the anion exchange properties of the hulls was developed. Ion exchange properties of the hulls toward anions of environmental significance, namely arsenate (As), chromate (Cr), dichromate (Cr₂), phosphate (P) and selenate (Se) were determined. The modified hulls were also compared with commercial cellulose‐based and synthetic anion exchange resins in their ability to remove these anions from solution. The experimental and commercial resins were also compared for their ability to remove a mixture of arsenate, chromate, dichromate and selenate from laboratory prepared solutions to levels below the maximum contaminant levels for these anions in drinking water as specified by the US Environmental Protection Agency (US EPA). Our results demonstrate that the soy hull resin is more efficient in anion removal than the commercial cellulose‐based resin but not as effective as the commercial synthetic resin. Published in 2003 for SCI by John Wiley & Sons, Ltd.     

Synthesis and electrochemical anion recognition by novel redox-responsive ferrocenoyl dipeptide ester derivatives; 1H NMR anion complexation studies

The synthesis of six N-ferrocenoyl dipeptide ester derivatives FcCOR (Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄); R=Gly-Gly(OMe) (1), Leu-Leu(OEt) (2), Ala-Phe(OEt) (3), Phe-Phe(OMe) (4), Phe-Leu(OBn) (5) and Phe-Ser(OEt) (6)) is described. The electrochemical anion sensing behaviour (using a platinum microdisk working electrode) and ¹H NMR anion coordination studies of these novel pendant N-ferrocenoyl dipeptide ester derivatives with a range of anions are reported.     

盐水中硫酸根的脱除技术

指出了盐水中硫酸根的危害，介绍了盐水生产中脱除硫酸根的主要技术方法。     

Transport of the dicyanogold(i) anion

We have shown that dicyanogold(I), [Au(CN)(2)](-) is a common metabolite found in blood and urine samples of patients treated with different gold based drugs. Some patients have high levels of gold within their red blood cells (RBCs). Size exclusion and C18 reversed phase chromatography show that the majority of the gold in RBC lysates is bound to protein, but small molecules such as dicyanogold(I) and gold-glutathione complexes are also present. Dicyanogold incubation with red blood cells in vitro leads to a rapid and complete uptake of gold. This uptake is unaffected by DIDS, an inhibitor of the anion channel, but is blocked by the addition of external cyanide. Dicyanogold is also readily taken up by H9 cells, a continuous CD(4+) cell line. This uptake is significantly inhibited by N-ethylmaleimide, suggesting a requirement for sulfhydryl groups. Dicyanogold inhibits the replication of the AIDS virus, HIV, in a cell culture model.