Molecular ions of 3,3′-bi(2-R-5,5-dimethyl-4-oxopyrrolinylidene) 1,1′-dioxides

The electrochemical reduction of 3,3′-bi(2-R-5,5-dimethyl-4-oxopyrrolinylidene) 1,1′-dioxides (R = CF₃, Me, Ph, Bu^t), which are cyclic dinitrons with conjugated C=C bond, in acetonitrile is an EE process producing stable radical anions and dianions, whereas the electrochemical oxidation is an EEC (R = Me, Ph) or EE process (R = Bu^t) with formation of radical cations (except for the case of R = CF₃) and dications (R = Bu^t) stable under standard conditions. Radical cations of the dioxides with R = Me, Ph, and Bu^t and radical anions of the whole series of the compounds studied, including R = CF₃, were characterized by ESR spectroscopy combined with electrochemical measurements and quantum-chemical calculations. The electrochemical behavior of the Bu^t-substituted dinitron is unique: the EE processes in the region of negative and positive potentials with formation of the dianion, radical anion, radical cation, and dication stable at T = 298 K were observed for the first time within one cycle of potential sweep in the CV curve measured in MeCN. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1148–1154, May, 2005.     

Synthesis,photophysical and NMR evaluations of thiourea-based anion receptors possessing an acetamide moiety

The synthesis and photophysical evaluation of three diaryl thiourea-based anion receptors (4–6) for comparison with their urea counterparts (1–3) is outlined. These anion receptors posses an acetamide functionality on one of the aryl groups and an electron-withdrawing CF₃ group on the other. By varying the position of the acetamide group, in the o-, m- and p-positions of 4–6, respectively, the anion binding ability was both tuneable and found to be, in some cases, significantly different from that seen for the urea analogues 1–3. The binding affinities of the receptors 4–6, as well as the binding stoichiometries, were evaluated using UV–vis absorption spectroscopy in MeCN. However, these receptors were not sufficiently emissive to quantify the anion recognition using fluorescence. The results confirmed strong binding of these receptors to anions such as fluoride, acetate, phosphate, pyrophosphate and chloride. Nevertheless, the overall results obtained did not conform to the anticipated trends seen for 1–3, which is most likely due to the enhanced binding affinity of the thiourea analogues 4–6. The binding interactions were also investigated by using ¹H NMR which confirmed that these receptors interacted with the anions in a stepwise manner, where the primary anion binding interaction occurred at the thiourea side, which led to an activation of the acetamide moiety towards the second anion binding interaction, an example of an allosteric activation mode.     

Leveraging Material Properties in Fluorescence Anion Sensor Arrays: A General Approach

As the demand for probes suitable for sensor development increases, investigation of approaches that utilize known successful receptors gains in general importance. This study describes a two‐prong approach that can be used as a guide to developing sensors from known receptors. First, the conversion of a simple receptor, calix[4]pyrrole, into a fluorescent probe to establish a ratiometric signal is described. Secondly, the sensors that employ an output from a single ratiometric calix[4]pyrrole probe are fabricated by using poly(ether‐urethane) hydrogel copolymers. These hydrogels are designed to absorb, internalize and transport aqueous electrolytes. A sensor array of ten different poly(ether‐urethane) matrices with varying comonomer proportions were doped with a single probe and were exposed to eight different anions: acetate, benzoate, fluoride, chloride, phosphate, pyrophosphate, hydrogen sulfide, and cyanide, eight urine samples and anti‐inflammatory drugs (NSAIDs). The poly(ether‐urethane) matrices comprise different proportions of anion‐binding urethane moieties and different hydrophilicity given by the ratio between ethylene glycol ether and butylene glycol ether. This diversity in the hydration behavior provides different environment polarity, in which the recognition and self‐assembly processes display enough diverse behavior to allow for unique response of the probe to the analytes. Furthermore, a single probe is shown to recognize eight different aqueous anions and eight urine samples when embedded in ten different polyurethanes in an array that displays 100 % classification accuracy. To demonstrate the potential of the concept for quantitative studies, an estimation of non‐steroidal anti‐inflammatory drugs ibuprofen and diclofenac in water and in saliva was performed. A limit of detection of 0.1 ppm and a dynamic range of 0.1–0.6 and 0.05–60 ppm was observed, respectively. Given the general difficulty of chemosensors to recognize aqueous anions, the fact that one probe recognizes eight different analytes attests to an enormous effect of the polymer environment on the recognition process. This method could be used to generate a variety of sensor arrays for various analyses including species that are difficult to recognize, such as small‐molecule‐ and inorganic anions.     

Solvent‐assisted anionic ring opening polymerization of glycidol: Toward medium and high molecular weight hyperbranched polyglycerols

Hyperbranched polyglycerols (HPGs) are globular structures with a large number of functionalizable hydroxyl groups and have excellent in vitro and in vivo biocompatibility profiles comparable to polyethylene glycol. This work introduces a facile method for the synthesis of medium molecular weights (M_ws) (50–300 kDa) HPGs, which has been difficult to synthesize with low polydispersity, with the assistance of solvents by ring opening polymerization. The influence of different solvents (1,4‐dioxane, tetrahydropyran (THP), ethylene glycol diethyl ether (EGDE) and decane), solvent to glycidol ratio, concentration of glycidol and the time of polymerization on M_w and polydispersity of HPGs has been studied. The M_w and polydispersity of HPGs are significantly affected by the nature of the polymerization phase (homogeneous or heterogeneous) and chemical structure of the solvent. The differences in the solvation of the potassium cations and change in the nucleophilicity of the alkoxide anion in various solvents may be responsible for the changes in M_w and PDI of the HPG. The M_w of the HPG decreases in the order 1,4‐dioxane > THP > EGDE >decane. The microstructure, solution and thermal properties of the HPG do not depend on the nature of solvent. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2614–2621     

反相高效液相色谱法分析无机阴离子研究

本文研究了提高ＲＰ－ＨＰＬＣ测定无机阴离子的选择性的方法，设计了利用对离子试剂和背景试剂兼作ｐＨ调节剂，建立了几种分离分析系统和实际样品分析方法。     

Synthesis of trans-fused polycyclic ethers with angular methyl groups using sulfonyl-stabilized oxiranyl anions

An efficient method has been developed for the synthesis of trans-fused tetrahydropyrans with angular methyl groups adjacent to the ring oxygen. The procedure involves the coupling reaction of a sulfonyl-stabilized oxiranyl anion with an appropriate triflate followed by 6-endo cyclization, and is effective for the construction of 6/6- and 6/7/6-cyclic ether ring systems with sterically congested 1,3-diaxial methyl groups.     

Treatment of anions in SINDO1

The SINDO1 method is modified to include the calculation of molecular anions. Two versions of modifications are presented which are based on charge dependent orbital exponents. Calculated heats of formation and electron affinities are much improved compared to the standard version with fixed orbital exponents.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday     

固相萃取净化-离子色谱测定不同生长期新鲜烟叶中的7种无机阴离子

目的 为了研究不同生长期新鲜烟叶中无机阴离子的含量和变换规律,建立了一种固相萃取净化/离子色谱方法测定新鲜烟叶中的7种无机阴离子（F-,Cl-,Br-,NO2-,NO3-,SO42-,PO43-）。方法 样品经0.1 mol/L NaOH水溶液超声提取,萃取液经RP1.0cc固相萃取柱净化后,使用AS11-HC（4 mm×250 mm）色谱柱进行分离,以KOH为流动相,梯度洗脱。 结果 7种无机阴离子在0.10-5.0 μg/mL范围内具有较好的线性（r>0.996）,检出限在0.01-0.04 μg/mL之间,定量限在0.04-0.14 μg/mL之间,加标回收率为96.3%～102.1%,相对标准偏差（RSD%）在2.7%~4.8%之间。结论 方法前处理操作简单,7种无机阴离子分离好,检测灵敏准确,可用于不同生长时期新鲜烟叶样品中多种无机阴离子含量的检测分析。