通过超宽139La固体核磁共振波谱研究层状La(OH)2NO3

层状稀土氢氧化物是一类新型的稀土功能材料，本文采用固体核磁共振（SSNMR）方法研究了同时具备离子交换能力和非线性光学特性的层状La（OH）₂NO₃化合物，探讨了通过四极核CPMG（QCPMG）脉冲序列和变频谱图采集获取超宽¹³⁹La SSNMR谱图的方法，并描述了适用于此类实验的滤波方程和谱图重建方法.重建谱图同时包含四极核中心跃迁和卫星跃迁信息，本文使用QUEST软件对超宽¹³⁹La NMR谱图进行了模拟，获取的四极耦合常数C_Q和非对称因子η_Q均与CASTEP密度泛函理论计算值高度吻合.SSNMR实验结果证实层状La（OH）₂NO₃化合物属于非中心对称结构（P2₁），解决了对其结构长期以来存在的争论.     

Analysis of new psychoactive substances in human urine by ultra‐high performance supercritical fluid and liquid chromatography: Validation and comparison

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism, which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute‐filter‐and‐shoot protocol utilizing propan‐2‐ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3 min) and short total analysis time. Precision was well <15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3 ng/mL, except for cathinone (5 ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes.     

Enhanced headspace single drop microextraction method using deep eutectic solvent based magnetic bucky gels: Application to the determination of volatile aromatic hydrocarbons in water and urine samples

A facile headspace single drop microextraction method was developed using deep eutectic solvent‐based magnetic bucky gel as the extraction solvent for the first time. The hydrophobic magnetic bucky gel was formed by combining choline chloride/chlorophenol deep eutectic solvent and magnetic multiwalled carbon nanotube nanocomposite. Magnetic susceptibility, high viscosity, high sorbing ability, and tunable extractability of organic analytes are the desirable advantages of the prepared gel. Using a rod magnet as a suspensor in combination with the magnetic susceptibility of the prepared gel resulted in a highly stable droplet. This stable droplet eliminated the possibility of drop dislodgement. The prepared droplet made it possible to complete the extraction process in high temperatures and elevated agitation rates. Furthermore, using larger micro‐droplet volumes without any operational problems became possible. These facts resulted in shorter sample preparation time, higher sensitivity of the method, and lower detection limits. Under the optimized conditions, an enrichment factor of 520–587, limit of detection of 0.05–0.90 ng/mL, and linearity range of 0.2–2000 ng/mL (coefficient of determination = 0.9982–0.9995) were obtained. Relative standard deviations were < 10%. This method was successfully coupled with gas chromatography and used for the determination of benzene, toluene, ethylbenzene, and xylene isomers as harmful volatile organic compounds in water and urine samples.     

Chemical profiling of bioactive constituents in hop cones and pellets extracts by online comprehensive two‐dimensional liquid chromatography with tandem mass spectrometry and direct infusion Fourier transform ion cyclotron resonance mass spectrometry

Humulus lupulus L. (hop) is highly interesting from a nutraceutical perspective. The hop phytocomplex contains a wide range of bioactive metabolites, and its characterization is challenging. To tackle such a task, for the first time we applied and compared a combined approach consisting of online comprehensive two‐dimensional liquid chromatography with tandem mass spectrometry and direct infusion Fourier transform ion cyclotron mass spectrometry. A reversed phase × reversed phase approach with a shifted gradient in the second dimension ensured selectivity and two‐dimensional space coverage. Hyphenation with an ion trap time‐of‐flight analyzer led to the identification of 83 compounds in 70 min, comprising a novel quercetin derivative and six unknown bitter acids. On the other hand, the direct infusion method was able to identify 40 analytes (except isomers) with high mass accuracy (≤ 0.1 ppm) in less than 1 min analysis time. The developed approach can be used in a complementary way, combining the separation capability and high informative spectra of two‐dimensional liquid chromatography tandem mass spectrometry with the ultra‐high mass accuracy of direct infusion, for potential compound discovery or the accurate profiling of bioactive compounds in different hop cultivars as well as for monitoring processing and storage of hop‐based products.     

Rapid analysis of ultraviolet filters using dispersive liquid–liquid microextraction coupled to headspace gas chromatography and mass spectrometry

An ionic‐liquid‐based in situ dispersive liquid–liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7–10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values.     

Deep oxidative desulfurization of benzothiophene and dibenzothiophene with a peroxophosphotungstate–ionic liquid brush assembly

A novel, efficient and reusable heterogeneous catalytic assembly of peroxophosphotungstate held in an ionic liquid brush was synthesized and an extraction and catalytic oxidative desulfurization (ECODS) procedure was developed for a model oil of benzothiophene (BT) and dibenzothiophene (DBT) using 30 wt% hydrogen peroxide as terminal oxidant and methanol as solvent under mild conditions. Several factors that affect sulfur removal were investigated in detail. The highest sulfur removal can reach 100% for BT in 7 h at 70 °C when the molar ratio of H₂O₂, S and catalyst is 10:1:0.025. The sulfur removal for DBT can also reach 100% in 4 h at 50 °C with the same molar ratio of H₂O₂, S and catalyst. The experimental results demonstrate that this ECODS process has no apparent scale‐up effect. The catalyst can be easily recovered (via simple filtration) and recycled five times without a significant decrease in activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and liquid crystalline behavior of bulky poly(methacrylamide)s

N‐(Bis(4‐(2‐ethylhexyloxy)phenyl)(phenyl)‐methyl)methacrylamide was synthesized and polymerized via reversible addition‐fragmentation chain‐transfer (RAFT) polymerization. The chain‐transfer agent (4‐cyano‐4‐(phenylcarbonothioylthio) pentanoic acid (CPADB)), combined with a chiral additive, and a radical initiator yielded polymers with dispersities between 1.2 and 1.4. At low concentrations, the polymers are soluble in hexanes and chloroform while at higher concentrations they swell in these solvents. Characterization of the polymers by wide‐angle X‐ray scattering (WAXS) revealed an interplanar distance of 19.0 Å. The WAXS data combined with polarized optical microscopy support a lamellar crystallization and lyotropic liquid crystalline behavior in hexanes and chloroform. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2563–2568     

Influence of Molar Mass and Concentration on the Thermogelation of Methylcelluloses

In this study, thermogelation of methylcelluloses is investigated in relation to the molar mass and concentration in aqueous medium. A large hysteresis between heating and cooling ramps was observed whatever the conditions. The heating process in particular was studied to analyze the two steps of gelation using rheometry. At low temperature, in the sol state, viscosity depends on the concentration and molar mass. Over 30°C a gel-like behavior was observed including two steps (the second step is a strong gel with phase separation) having storage moduli that are nearly independent of polymer molar mass but are directly related to polymer concentration.     

Protic Anions [H(B12X12)]− (X=F,Cl, Br,I) That Act as Brønsted Acids in the Gas Phase

The acidity of protic cations and neutral molecules has been studied extensively in the gas phase, and the gas‐phase acidity has been established previously as a very useful measure of the intrinsic acidity of neutral and cationic compounds. However, no data for any anionic acids were available prior to this study. The protic anions [H(B₁₂X₁₂)]^? (X=F, Cl, Br, I) are expected to be the most acidic anions known to date. Therefore, they were investigated in this study with respect to their ability to protonate neutral molecules in the gas phase by using a combination of mass spectrometry and quantum‐chemical calculations. For the first time it was shown that in the gas phase protic anions are also able to protonate neutral molecules and thus act as Brønsted acids. According to theoretical calculations, [H(B₁₂I₁₂)]^? is the most acidic gas‐phase anion, whereas in actual protonation experiments [H(B₁₂Cl₁₂)]^? is the most potent gas‐phase acidic anion for the protonation of neutral molecules. This discrepancy is explained by ion pairing and kinetic effects.     

Effect of branched alkyl side chains on the performance of thin‐film transistors and photovoltaic cells fabricated with isoindigo‐based conjugated polymers

New isoindigo and di(thienyl)ethylene‐containing π‐extended conjugated polymers with different branched side chains were synthesized to investigate their physical properties and device performance in thin‐film transistors and photovoltaic cells. 11‐Butyltricosane (S3) and 11‐heptyltricosane (S6) groups were used as side‐chain moieties tethered to isoindigo units. The linking groups between the polymer backbone and bifurcation point in the branched side chain differ in the two polymers (i.e., PIDTE‐S3 and PIDTE‐S6 ). The polymers bearing S6 side chains showed much better charge transport behavior than those with S3 side chains. Thermally annealed PIDTE‐S6 film exhibited an outstanding hole mobility of 4.07 cm² V^?1 s^?1 under ambient conditions. Furthermore, bulk heterojunction organic photovoltaic cells made from a blend film of PIDTE‐S3 and (6,6)‐phenyl C61‐butyric acid methyl ester demonstrated promising device performance with a power conversion efficiency in the range of 4.9–5.0%. © 2015 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 2015 , 53, 1226–1234