Structure of the 18-Crown-6 Complex with Ammonium Hexafluorosilicate and Water

The crystalline host–guest type complex [(18-crown-6NH₄)₂][SiF₆]4H₂Ohas been obtained as the result of the interaction of SiF₄2NH₃ with 18-crown-6 (18C6) in an aqueous medium. Crystal data: monoclinic, space groupC 2 c, a=26.541(2), b=8.363(2), c=20.469(2) Å, = 122.43(1)°and Z=4. The final R-value is 0.070 for 3253 reflections with I 2(I).The crystals consist of the complex [NH₄18C6]⁺ cations, [SiF₆]^2-anions and water molecules. The ammonium cation is hydrogen bonded by three of its H-atoms to the crown ether oxygen atoms with N(1) O separations2.923(5)–2.940(5) Å and by the fourth H-atom to the fluorine atom of thehexafluorosilicate anion, the N(1)F(4) distance being 2.797(6) Å.The conformation of the macrocycle and the hydrogen-bond geometry in thecomplex cation closely resemble those in related adducts between 18-crown-6and ammonium salts. All crystal components are connected via a system of hydrogen bonds into a ribbon along the b axis in the unit cell.     

DX-300离子色谱测定山地冰川雪冰中的有机酸与无机酸阴离子

 利用AS4A SC分离柱 ,AG4A SC保护柱 ,ASRS Ⅱ抑制器 ,TAC 2阴离子富集柱和ATC 1阴离子捕集柱 ,以四硼酸钠 (Na2 B4O7)为淋洗液试剂 ,2 5mmol/LH2 SO4为化学抑制的再生液 ,采用梯度淋洗方式 ,对中国天山乌鲁木齐河源一号冰川雪冰中的生物有机酸和无机酸阴离子进行了测试分析。 2mL雪冰融水样品可在 16min内通过一次进样检测出氟离子、乙酸根离子、甲酸根离子、丙酮酸根离子、一氯乙酸根离子、氯离子、亚硝酸根离子、溴离子、硝酸根离子、磷酸根离子、硫酸根离子和草酸根离子共 10多种有机酸和无机酸阴离子。     

紫外光降解-离子色谱法测定液晶化合物中的阴离子

 采用紫外光降解 离子色谱法测定了液晶材料中的阴离子。建立了样品前处理的方法 ,研究了样品光降解的条件及样品测定的最佳色谱参数。结果表明 ,该液晶材料样品中含有F-,Cl-,NO2 -,Br-和I-等 5种阴离子。用DionexOnGuardRP及P型前处理柱过滤可有效去除光解后样品基体中的有机物。光解时加入H2 O2 可显著提高光解效率 ,在样品基体中加入NaOH使该方法可准确测定样品中的I-。F-,Cl-,NO2 -和Br-在光解时间约为 2 0h时达到最大离解效率 ,I-在光解 1 5h时达到最大离解效率。采用DionexIonPacAS16色谱柱 ,整个样品的测定可在 2 5min内完成。     

Regioselective hydrogen-deuterium exchange in the [B10H10]2– anion. Syntheses of [1,10-B10H8D2]2– and [2,3,4,5,6,7,8,9-B10H2D8]2–

Decahydro-closo-decaborate anion, [B₁₀H₁₀]^2–, undergoes regioselective deuterio-exchange in methanol-d₄. Selectively deuterated derivatives [1,10-B₁₀H₈D₂]^2– and [2,3,4,5,6,7,8,9-B₁₀H₂D₈]^2– were synthesized.     

Fluoride anion sensing mechanism of a BODIPY‐linked hydrogen‐bonding probe

The sensing mechanism of a fluoride‐anion probe BODIPY‐amidothiourea ( 1c ) has been elucidated through the density functional theory (DFT) and time‐dependent density functional theory (TDDFT) calculations. The theoretical study indicates that in the DMSO/water mixtures the fluorescent sensing has been regulated by the fluoride complex that formed between the probe 1c /two water molecules and the fluoride anion, and the excited‐state intermolecular hydrogen bond (H‐B) plays an important role in the fluoride sensing mechanism. In the first excited state, the H‐Bs of the fluoride complex 1cFH₂ are overall strengthened, which induces the weak fluorescence emission. In addition, molecular orbital analysis demonstrates that 1cFH₂ has more obvious intramolecular charge transfer (ICT) character in the S₁ state than 1cH₂ formed between the probe 1c and two water molecules, which also gives reason to the weaker fluorescence intensity of 1cFH₂ . Further, our calculated UV‐vis absorbance and fluorescence spectra are in accordance with the experimental measurements. © 2018 Wiley Periodicals, Inc.     

A systematic tandem mass spectrometric study of anion attachment for improved detection and acidity evaluation of nitrogen‐rich energetic compounds

The development of rapid, efficient, and reliable detection methods for the characterization of energetic compounds is of high importance to security forces concerned with terrorist threats. With a mass spectrometric approach, characteristic ions can be produced by attaching anions to analyte molecules in the negative ion mode of electrospray ionization mass spectrometry (ESI‐MS). Under optimized conditions, formed anionic adducts can be detected with higher sensitivities as compared with the deprotonated molecules. Fundamental aspects pertaining to the formation of anionic adducts of 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX), 1,3,5‐trinitro‐1,3,5‐triazinane (RDX), pentaerythritol tetranitrate (PETN), nitroglycerin (NG), and 1,3,5‐trinitroso‐1,3,5‐triazinane energetic (R‐salt) compounds using various anions have been systematically studied by ESI‐MS and ESI tandem mass spectrometry (collision‐induced dissociation) experiments. Bracketing method results show that the gas‐phase acidities of PETN, RDX, and HMX fall between those of HF and acetic acid. Moreover, PETN and RDX are each less acidic than HMX in the gas phase. Nitroglycerin was found to be the most acidic among the nitrogen‐rich explosives studied. The ensemble of bracketing results allows the construction of the following ranking of gas‐phase acidities: PETN (1530‐1458 kJ/mol) > RDX (approximately 1458 kJ/mol) > HMX (approximately 1433 kJ/mol) > nitroglycerin (1427‐1327.8 kJ/mol).     

Facile preparation of 3-substituted 2-quinazolinones via electrogenerated base

A new series of 3,4-disubstituted quinazolin-2-ones, with potential T-type calcium channel antagonist activity, and new 4-methylene-quinazolin-2-ones, promising catalysts as N-heterocyclic olefins, have been prepared in good yield by a simple reaction between 2-aminobenzophenone, or 2-aminoacetophenone, and cyanomethyl anion electrogenerated by acetonitrile reduction at a graphite electrode, followed by the addition of different organic isocyanates and subsequent heterocyclization.     

Access to the Bis‐benzene Cobalt(I) Sandwich Cation and its Derivatives: Synthons for a “Naked” Cobalt(I) Source?

The synthesis and structural characterization of the hitherto unknown parent Co(bz)₂⁺ (bz=benzene) complex and several of its derivatives are described. Their synthesis starts either from a CoCO₅⁺ salt, or directly from Co₂(CO)₈ and a Ag⁺ salt. Stability and solubility of these complexes was achieved by using the weakly coordinating anions (WCAs) [Al(OR^F)₄]^? and [F{Al(OR^F)₃}₂]^? {R^F=C(CF₃)₃} and the solvent ortho‐difluorobenzene (o‐DFB). The magnetic properties of Co(bz)₂⁺ were measured and compared in the condensed and gas phases. The weakly bound Co(o‐dfb)₂⁺ salts are of particular interest for the preparation of further Co^I salts, for example, the structurally characterized low‐coordinate 12 valence electron Co(P^tBu₃)₂⁺ and Co(NHC)₂⁺ salts.     

阴离子交换树脂回收水相中有机磷酸萃取剂

研究了阴离子交换树脂对水相中有机磷酸萃取剂的吸附。 通过比较不同的离子交换树脂对水相中2-乙基己基膦酸-单-2-乙基己基酯(P507)的去除率,发现大孔强碱性阴离子交换树脂(D201-OH)从水溶液中去除P507的能力最强,去除率可达99.24%。 而且当溶液在pH=1.0时,D201-OH对P507的吸附主要是分子吸附,其吸附等温线更适用于Langmuir模型;当溶液在pH=5.0时,阴离子交换反应占主导地位,其吸附等温线更适用于Freundlich模型。 研究还表明,D201-OH对P507的吸附在20 min内即达到吸附平衡时99.8%的吸附量。 通过动力学研究表明,拟一级动力学模型(R²>0.99)更适用于描述实验数据,并且吸附速率主要受膜扩散控制。 此外,吸附-解吸附循环8次后,D201-OH的吸附能力仍然保持在93%以上。 综上所述,D201-OH是有机磷酸类萃取剂的良好吸附剂,其吸附性能高效,循环过程稳定,因此可用于实际生产过程中回收有机磷酸萃取剂。     

甲烷氧化菌素功能化纳米金修饰电极模拟SOD的电化学性能研究

利用混合自组装的方式,将Mb功能化纳米金（Mb-AuNPs-MUA）修饰在金电极表面,以制备出检测超氧阴离子无电子媒介体生物传感器.采用UV-Vis考察修饰纳米团簇的相关特征,利用修饰电极检测DMSO/NaOH体系产生的超氧阴离子.试验结果表明：该修饰电极对超氧阴离子的歧化反应具有显著的催化活性,计算出异相电子传递速率常数（K_s）为0.041 cm/s,电子转移系数（α）为0.435.在0.06~0.2 μmol/L范围内,超氧阴离子浓度与峰电流呈良好的线性关系,相关系数R²为0.9719,方法检出限（LOD）为1.129×10^-3 μmol/L（S/N=3）、3.683×10^-3 μmol/L（S/N=10）,精密度试验测定得相对标准偏差（RSD,n=9）为3.83%.