Iodate Sensing Electrodes Based on Phosphotungstate‐ Doped‐Glutaraldehyde‐Cross‐Linked Poly‐L‐lysine Coatings

Glassy carbon electrode modified with phosphotungstate‐doped‐glutaraldehyde‐cross‐linked poly‐L ‐lysine (PLL‐GA‐PW) film was employed for iodate determination. The PLL‐GA‐PW film electrode shows excellent electrocatalytic activity towards iodate reduction with significant reduction of overpotential. Under optimized experimental conditions, a linear range from 5×10^?8 to 2.27×10^?2 M with a sensitivity of 61.75 μA mM^?1 was obtained. Possible interfering species, in iodate determination, were evaluated and the applicability of proposed sensor for iodate estimation in table salt was also demonstrated. The PLL‐GA‐PW film electrode shows fast response, wider linear range, and good selectivity and stability.     

二空缺Dawson型钨磷酸盐K_(10)Na_2H_2P_2W_(16)O_(60)·18H_2O的合成、结构和溶液的稳定性

用刚酸化的Na_2WO_4溶液(H~+/WO_4~(2-)=1.14,摩尔比)与Na_2HPO_4混合,酸化至pH6.5～6.9,再加入KCl固体,可制得K_(10)Na_2H_2P_2W_(16)O_(60)·18H_2O晶体。经元素分析、VO~(2+)光度滴定、~(31)PNMR、~(183)W NMR和紫外光谱等研究,确定为二空缺Dawson型结构;其溶液经60℃加热后,立即分解成H_7PW_8O_(33)~(6-);将K~+换成Na~+时,主要分解产物为PW_(11)O_(39)~(7-)。     

Tetracycline Sensitive Membrane Electrodes Based on Poly (Vinyl Chloride) Matrices and their use in Drug Analysis

ABSTRACT

Tetracycline hydrochloride-selective electrodes of both the coated wire and the conventional polymer membrane types have been prepared. They are based on incorporating the tetracycline-phosphotungstate ion-associate in plasticized poly(vinyl chloride) film. A Nernstian response is shown by these electrodes within certain concentration ranges depending on the type of electrode. The effect of pH of the test solution and time of soaking on the electrodes' performance are studied. The electrodes are highly selective for tetracycline with respect to several inorganic cations, sugars and some amino-acids of significant importance in biological fluids and pharmaceutical preparations. The standard cell potentials, E°, were determined at different temperatures and used to calculate the isothermal temperature coefficient of the cell. Tetracycline is determined successfully in pure solutions and in pharmaceutical preparation using the standard additions method and potentiometric titration.     

（TEAH）nH3-nPW12O40催化苯甲醇选择氧化及其反应机理

以Keggin结构的磷钨酸和三乙胺（TEA）为原料,通过简单的酸碱反应合成了磷钨酸的TEA盐.并以它们为催化剂,考察了以H₂O₂为氧化剂、以水为溶剂的体系中苯甲醇选择氧化制备苯甲醛的反应性能.结果表明,（TEAH）_nH_3-nPW₁₂O₄₀（n=1,2,3）系列催化剂对苯甲醇的选择氧化反应有很高的活性和选择性,且可被分离和循环使用.在适宜的反应条件下,最佳催化剂（TEAH）H₂PW₁₂O₄₀上,苯甲醇的转化率可达99.6%,苯甲醛的选择性为100%.还采用IR,³¹PNMR谱和元素分析技术,对催化剂和反应过程中催化剂物种的转化和分布进行了考察,进而导出了反应机理.在这个水--油两相反应中,（PW₁₂O₄₀）^3-首先在H₂O₂的作用下,氧化降解为溶于水的小分子过氧物种（PO₄（WO（O₂）₂）₄）^3-和自由W物种.（PO₄（WO（O₂）₂）₄）^3-是真正的活性物种,可将部份溶于水层的苯甲醇氧化为苯甲醛,自身转变为失去活性氧的反应后物种（SAR）.而SAR又可与自由W物种一起聚合为前驱体状态的（PW₁₂O₄₀）^3-,完成催化循环.     

Chemical, electrical and electrochemical characterization of hybrid organic/inorganic polypyrrole/PW12O40 coating deposited on polyester fabrics

A study of the stability of conducting fabrics of polyester (PES) coated with polypyrrole/PW₁₂O₄₀³⁻ (organic/inorganic hybrid material) in different pH solutions (1, 7, 13) has been done. Washing tests were also done in views of its possible application in electronic textiles such as antistatic clothing. X-ray photoelectron spectroscopy (XPS) studies have been done to quantify the amount of counter ion that remains in the polymer matrix and determine the doping ratio (N⁺/N) after the different tests. Scanning electron microscopy (SEM) was also used to observe morphological differences after the different tests. Surface resistivity changes were measured by means of electrochemical impedance spectroscopy (EIS). Scanning electrochemical microscopy (SECM) was employed to measure changes in electroactivity after the different tests. Higher pHs caused a decrease of the doping ratio (N⁺/N), the loss of part of the counter ions and the decrease of its conducting and electrocatalytic properties. The stability in acid media and neutral media and after the washing test was good. Only at pH 13 the loss of the counter ion was widespread and there was a decrease of its conducting and catalytic properties; although the fabrics continued acting mainly as a conducting material.     

Organic Molecule Modified Phosphotungstate with Helical Structure for Electrochemical Detection of Dopamine

To overcome the water solubility and aggregation of heteropoly acids (HPAs), and to promote its application in the electrochemical biosensors, organic molecular modification strategy was employed by simple hydrothermal synthesis. Herein, an unprecedented phosphotungstate (PTA)-based three-dimensional supramolecular framework with helical structure, [(bix)₂(H₃PW₁₂O₄₀) · H₂O] [PTA-bix, bix = 1,3-bis(imidazol-1-ylmethyl) benzene], was synthesized and characterized. And the PTA-bix modified glassy carbon electrode shows the high sensitivity and catalytic activity for detecting the neurotransmitter dopamine (DA) with the linear detection range from 1 μM to 100 μM, and the detection limit of differential pulse voltammetry (DPV) is 0.85 μM. The concept behinds the new architecture to modify electrodes should promote the further development of HPA hybrid crystal material-based biosensors.     

A polypseudorotaxane coordination polymer comprising Preyssler-type phosphotungstate and flexible N-donor ligands

A coordination polymer based on Preyssler-type phosphotungstate, {Cu₄(L)₂(HL)(H₂O)₅[HNa(H₂O)P₅W₃₀O₁₁₀]}·2H₂L·4H₂O (1), has been hydrothermally synthesized and characterized by single crystal X-ray diffraction, powder X-ray diffraction, IR spectrum, element analysis, and thermogravimetric analysis. The structure shows that the asymmetry coordination of the N-donor ligands results in formation of chiral sub-building blocks (SBUs). The chiral SBUs were connected by Cu–O bonds and organic ligands to form a two-dimensional (2-D) structure. Furthermore, 1 represents the first 2D + 2D → 2D polypseudorotaxane framework based on the chiral lamellar structure; magnetic properties have been investigated as well.     

含磷无机盐添加剂对甲醇羰基化反应的助催化作用研究

以Rh(OAc) 2 为催化剂,以钠、锌和铵的磷酸盐以及钠的磷钼酸盐和磷钨酸盐作为添加剂,在催化甲醇羰基化制乙酸的反应中系统考察了不同添加剂对反应的影响。实验表明,加入添加剂后可显著提高该反应体系的催化活性。其中磷酸盐系列以磷酸铵的助催化效果最好,该催化体系醋酸的时空收率能达到40mol (L·h)以上。磷钼酸钠催化体系在温度较高时醋酸的时空收率高于磷钨酸钠,达到3 5mol (L·h)以上。     

Chemical and electrochemical polymerisation of pyrrole on polyester textiles in presence of phosphotungstic acid

Polypyrrole (PPy) was chemically synthesised on polyester (PES) textiles to produce conducting textiles. Two different types of counter ion were employed: anthraquinone sulfonic acid (AQSA) and phosphotungstate (). Textiles covered with PPy were characterised by means of FTIR-ATR, SEM, EDX, cyclic voltammetry (CV), surface resistivity measurements and electrochemical impedance spectroscopy (EIS). Additionally, friction and washing assays were done to test the resistance of the layer of conducting polymer (PPy/). Electropolymerisation of PPy/ in acetonitrile medium onto chemically synthesised PES-PPy/ showed the improvement of the coating properties.     

Syntheses,structures and properties of four organic–inorganic hybrid nicotinate-bridging rare-earth-containing phosphotungstates

Four novel organic–inorganic hybrid nicotinate-bridging dimeric rare-earth (RE)-containing phosphotungstates [H₂N(CH₃)₂]₈[RE(H₂O)(NA)(α-HPW₁₁O₃₉)]₂·24H₂O (RE = Ho^III for 1, Er^III for 2, Tb^III for 3, Dy^III for 4; HNA = nicotinic acid) have been synthesized from the reaction of trivacant Keggin precursor Na₉[α-PW₉O₃₄]∙16H₂O, RE(NO₃)₃·6H₂O, HNA by employing dimethylamine hydrochloride as organic solubilizing agent in the conventional aqueous solution system, which have been further characterized by elemental analyses, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Structural analysis indicates that the hybrid dimeric {[RE(H₂O)(NA)(α-HPW₁₁O₃₉)]₂}⁸⁻ polyoxoanion in 1–4 can be considered as two head-to-head mono-RE-containing Keggin [RE(H₂O)(NA)(α-HPW₁₁O₃₉)]⁴⁻ subunits bridged by two (η²,μ-1,1)-nicotinate linkers, which stands for the first organic–inorganic hybrid RE-containing phosphotungstates functionalized by nicotinate ligands. What's more, the solid-state photoluminescence properties and lifetime decay behaviors of 1–4 have been measured at room temperature and their photoluminescence spectra display the characteristic emission bands of corresponding trivalent RE cations.