A solid-contact Pb-selective electrode using poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene) as ion-to-electron transducer

In this work, a novel all-solid-state polymeric membrane Pb²⁺-selective electrode was developed by using for the first time poly(2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) as solid contact. To demonstrate the ion-to-electron transducing ability of MEH-PPV, chronopotentiometry and electrochemical impedance spectroscopy measurements were carried out. The proposed electrodes showed a Nernstian response of 29.1 mV decade⁻¹ and a lower detection limit of subnanomolar level. No water film was observed with the conventional plasticized PVC membrane. This work demonstrates a new strategy for the fabrication of robust potentiometric ion sensors.     

A polypyrrole-based solid-contact Pb<Superscript>2+</Superscript>-selective PVC-membrane electrode with a nanomolar detection limit

Ion-selective electrodes (ISE) based on conventional plasticized PVC membranes with solid inner contact (SC) have so far had unsatisfactory lower detection limits. Here it is shown that electropolymerization of pyrrole in the presence of potassium hexacyanoferrate(II)/(III) on Pt results in adequate inner contact for SC-ISE. The nanomolar lower detection limit achieved with the Pb²⁺-selective PVC membranes investigated is comparable with values obtained with optimized internal solutions of liquid-contact ISE.     

A highly selective solid-contact electrode for Ag~+ based on a monoazathiacrown ether ionophore

A new solid-contact Ag⁺-selective electrode was prepared with 9,10,12,13,24,25-hexahydro-5H,15H,23H-dibenzo [b,q][1,7,10,13,19,4,16]-entathiadiazacyclodocosine-6,16（7H,17H）-dione as ionophore,and cc,a>-dihexylsexithiophene（DH- 6T） ion-to-electron transducer.The sensor exhibited a working concentration range of 10⁸ to 10^-3 mol/L,with a near-Nernstian slope of 55.1±0.2 mV/dec and detection limit of 1.7×10^-9 mol/L.The fabricated electrodes demonstrated excellent selectivity over the most common monovalent and divalent cations.     

A simple approach for fabricating solid-contact ion-selective electrodes using nanomaterials as transducers

A simple and robust approach for the development of solid-state ion-selective electrodes (ISEs) using nanomaterials as solid contacts is described. The electrodes are fabricated by using the mixture of an ionic liquid (IL) and a nanomaterial as intermediate layer, formed by melting the IL. Tetradodecylammonium tetrakis(4-chlorophenyl)borate (ETH 500) is chosen as an model of IL to provide strong adhesion between the inner glassy carbon electrode and the intermediate layer. Nanomaterials including single-walled carbon nanotubes (SWCNTs) and graphene were used as active ion-to-electron transducers between the glassy carbon electrode and the ionophore-doped ISE membrane. By using the proposed approach, the solid-contact Cu²⁺- and Pb²⁺-selective electrodes based on ETH 500/SWCNTs and ETH 500/graphene as transducers, respectively, have been fabricated. The proposed electrodes show detection limits in the nanomolar range and exhibit a good response time and excellent stability.     

Synthesis and characterization of high-integrity solid-contact polymeric ion sensors

High-integrity solid-contact (SC) polymeric ion sensors have been produced by using spin casting and electropolymerization techniques in the preparation of the SC employing the conductive polymer, poly(3-octylthiophene) (POT). The physical and chemical integrity of the POT SCs have been evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS). Furthermore, the electrochemical stability of SC polymeric ion sensors has been investigated using electrochemical impedance spectroscopy (EIS). The results of this study demonstrate that electropolymerization and spin casting methods also comprising annealing of the synthesized SC film are capable of producing SCs that are relatively free of imperfections such as pores and pinholes. This leads to electrochemically stable and robust polymeric ion sensors where the SC/sensor interface is resistant to the formation of a detrimental water layer that normally gives rise to spurious ion fluxes and a degradation in the sensitivity and selectivity of the SC polymeric ion sensor.     

脯氨酸与Cu、Cu+和Cu2+配位体系的计算研究

运用M06-2X和ωB97XD方法分别在6-311++G（2d,p）和TZVP基组水平上,对脯氨酸（Pro）的15种构象与Cu、Cu⁺和Cu²⁺形成的多种配合物的几何结构、能量学特征、振动光谱和电子结构等进行计算研究. 四种水平得到20种[Pro-Cu]、16种[Pro-Cu]⁺和16种[Pro-Cu]²⁺稳定结构. [Pro-Cu]和[Pro-Cu]⁺体系中出现12种Pro构象,而[Pro-Cu]²⁺体系中出现11种Pro构象,三种体系中最稳定的结构都不是由能量最低的Pro构象生成的. 在结构CI3、CI4、CII7和CII8中,Pro的羧基氢转移到亚氨基氮形成两性离子与Cu双配位结合. [Pro-Cu]^0/1+/2+体系四种水平计算相对能差范围逐渐增加,结合能分别在-60.0 --5.0 kJ·mol^-1、-340.0 --170.0 kJ·mol^-1和-1100.0 --860.0 kJ·mol^-1范围,配位体系中Pro的变形能逐渐增加. N―H和O―H键伸缩振动频率普遍发生红移,配位体系中部分电荷从Pro转移到Cu上,在[Pro-Cu]²⁺体系中单配位结构中电荷转移最多,约为单位负电荷.     

一种基于三苯胺类共轭聚合物荧光信号开启的汞离子检测方法

通过Suzuki反应合成出主链中含9,9-二(4-二苯胺基苯基)-3,6-芴的蓝光共轭聚合物—聚[2,7-(9,9-二辛基芴)-co-3,6-(9,9-二三苯胺基芴)] (36PFT).36PFT可特异地与I-相互作用,并淬灭36PFT的荧光.当I-的浓度为0.24 mmol/L时,36PFT的荧光淬灭程度可达95％,...     

Miniaturized back-side contact transducer for potentiometric sensors

A novel type of a miniature transducer for potentiometric sensors was designed and tested. The transducer is made from an ordinary printed circuit board using a typical technology. As a result, a back-side contact structure was obtained, which can be mounted in flow systems. The advantage of the fabrication process is its cheapness and flexibility in designing modified structures. The measurement properties of the transducer were tested as a chloride sensor. Then the structure was covered with polyHEMA and a potassium-selective membrane and tested as a potassium sensor. The performance and the long-term stability of the sensors with plasticized PVC and Siloprene based potassium-selective membranes were compared.     

同时测定海水中K+、Na+、Ca2+、Cl-的流动注射离子选择电极分析

建立了一种用于海水中K+、Na+、Ca2+、Cl-同时快速、自动测定的流动注射离子选择电极自动方法(FI-ISE-M),优化了方法的最佳条件:总离子强度调节液(TISAB)的组成为0.3 mmol/L K+、6.0 mmol/L Na+、1.4 mmol/L Ca2+、21.0 mmol/L Cl-及pH8.0的80 mmol/L的tris-H3BO3缓冲溶液,其流量为1.25mL/min;每次测定的样品用量仅为160μL,载流流量为1.42 mL/min,混合盘管长度为30cm(I.D.0.5 mm)。本方法的分析速度为100样/h,相对标准偏差为2.0%(n=11),标准添加回收率为94.9%～104.3%,测定范围分别为1.0～8.0 mmol/L K+、50～290 mmol/L Na+、3.2～16.0 mmol/L Ca2+、70～430 mmol/LCl-。本方法已应用于反渗透海水淡化系统的水质检测。     

Si-rhodamine based water-soluble fluorescent probe for bioimaging of Cu+

A Si-substituted rhodamine based water-soluble fluorescent probe bearing a tetrathia-azacrown was designed for fluorescence imaging of Cu⁺ with substantial affinity and selectivity.In physiological condition,the developed probe with outstanding water-solubility exhibits ultrahigh sensitivity to Cu⁺,ensuring the reliable fluorescence imaging in vivo.     

A Novel Naked-Eye and Dual-Channel Responsive Fluorescent Probe for Cu2+ Based on 3,4-Disubstituted-1,8-naphthalimide

A new 3,4-disubstituted-1,8-naphthalimide derivative H1 was designed and synthesized as a selective fluorescent probe for Cu²⁺ over miscellaneous metal ions in aqueous media. Upon mixing with Cu²⁺ in CH₃OH:H₂O (1:1, volume ratio), the increase of fluorescence intensity and a bathochromic shift of absorbance of H1 could be observed with a notable color response (changing from yellow to pink). Furthermore, Cu²⁺ coordinates to the probe H1 and a 1:1 metal-ligand complex was formed.     

11-Mercaptoundecanoic acid functionalized gold nanoclusters as fluorescent probes for the sensitive detection of Cu2+ and Fe3+ ions

Metal ions are physiologically essential,but excessive metal ions may cause severe risk to plants and animals.Here,we prepared gold nanoclusters(Au NCs) protected by 11-mercaptoundecanoic acid(11-MUA),which have excellent fluorescence properties for the detection of metal ions.The results showed that the copper ions(Cu~(2+)) and iron ions(Fe~(3+)) in the solution have obvious quenching effect on the fluorescence intensity of Au NCs.The detection range of Fe~(3+) was 0.8–4.5 mmol/L(R~2= 0.992) and 4.5–11.0 mmol/L(R~2= 0.997).And Cu~(2+) has a lower linear range(0.1–1.0 mmol/L,R2= 0.993).When EDTA was added into the reaction system,it was observed that the quenching effect of Cu~(2+) and Fe~(3+)on Au NCs showed different phenomenon.Then,the effect of metal ions on the fluorescence of Au NCs was investigated.The selective detection of Cu~(2+) was achieved by EDTA masking of Fe~(3+).In addition,we realized the metal ions detection application of Au NCs in the serum     

A highly selective fluorescence switch for Cu2+ and Fe3+ based on a new diarylethene with a triazole-linked rhodamine 6G unit

A new diarylethene compound with a triazole-linked rhodamine 6G unit attached to the imino group (1O) was designed and synthesized. According to the test results, the solution color and fluorescence color of diarylethene can be modulated by lights and metal ions. The solution color could change from colorless to light purple when irradiated with UV light. When Cu²⁺ was added to the diarylethene solution, the color of diarylethene solution became blue, the fluorescence color turned from dark to bright yellow. Although the solution color did not change by adding Fe³⁺, its fluorescence color varied from dark to yellow. Moreover, it was found that the complex ratio of the diarylethene to Cu²⁺ was 1:1 and the binding stoichiometry of the diarylethene to Fe³⁺ was also 1:1 based on the data of NMR, MS, and other experiments. Based on these findings, photochromic figure of the diarylethene with UV/Vis light, Cu²⁺ and Fe³⁺ was constructed. Furthermore, the logic circuit was designed by input signals (ultraviolet stimulus, visible light stimulus, Cu²⁺ (or Fe³⁺) and EDTA) and an output signal (fluorescent intensity at 566?nm (or 575?nm)).     

A comparative study of four 20-membered N2S4-crown ethers as ionophores for polymeric membrane silver selective electrodes

<正>Four 20-membered N_2S_4-monoazathiacrown ethers have been synthesized and explored as neutral ionophores for Ag~+-selective electrodes.Potentiometric responses reveal that the flexibility of the ligands has great effect on the selectivity and sensitivity to Ag~+ ions.The electrode based on ionophore 9,10,20,25-tetrahydro-5H,12H-tribenzo[b,n,r][1,7,10,16,4,13]tetrathiadiaza cycloicosine 6,13-(7H,14H)-dione(C) with 2-nitrophenyl octyl ether(o-NPOE) as solvent in a poly(vinyl chloride)(PVC) membrane matrix shows a measuring range of 1.0×10~(-6) to 1.0×10~(-3) mol/L with a Nernstian slope of 54.9±0.3 mV/decade.This electrode has high selectivity for Ag~+ with negligible interference from many other cations and can be used in a wide pH range of 3.6-9.2.     

β-环糊精调控水溶液中Cu2+的辐射还原

在β-环糊精(β-CD)水溶液的安全吸收剂量范围内, 利用β-CD来调控Cu2+的辐射还原. 随着β-CD的加入, 硝酸铜的辐射还原产物从Cu2O 逐渐转变为Cu. 当β-CD浓度增大至8.0 mmol·L-1时, 辐射还原产物主要为Cu纳米粒子. 在辐照过程中, Cu2+的还原没有经历Cu2O的中间过程. 这是由于β-CD对·OH的清除减少了·OH与水化电子(e-aq)的反应, 增大了e-aq的产额, 从而有利于Cu的生成. 另外, β-CD通过羟基在Cu纳米粒子表面的吸附可增强Cu纳米粒子在水溶液中的稳定性. 用紫外-可见(UV-Vis)吸收光谱、粉末X射线衍射(XRD)和选区电子衍射(SAED)对Cu2+辐射还原产物进行了表征.     

Selective hydrogenation of dimethyl maleate to tetrahydrofuran over Cu/SiO2 catalyst: Effect of Cu+ on the catalytic performance

Cu/SiO_2 catalysts prepared by different methods have been investigated focusing on the influence of Cu~+on the catalytic performance.The composition,structure and copper valence state were characterized by means of BET,XRD,XPS,FTIR,N_2O-titration.It was found that the Cu/SiO_2 prepared by ammoniaevaporation(AE) method had much higher TOF value than that prepared by wetness-impregnation(WI)with the same THF selectivity.The higher TOF value was attributed to the coexistence of Cu~+ and Cu~0species in the activated AE-Cu/SiO_2.while only Cu° species existing in the activated Wl-Cu/SiO_2.Researches suggest that Cu~+ can adsorb and polarize the C=0 bond of DMM.It is concluded that Cu°could be the main active site and the synergistic effect between Cu~0 and Cu~+ could contribute to hydrogenation of DMM to THF.     

新型抑菌Cu2+固载超滤膜的制备及性能表征

将聚乙烯亚胺(PEI)通过静电作用自组装于聚丙烯腈(PAN)多孔基膜表面,形成高分子聚电解质层;进一步通过浸泡法和动态电沉积法,将Cu2+固载于高分子聚电解质层上,制备出新型Cu2+固载超滤膜.研究结果表明,Cu2+固载超滤膜的PEI层和Cu2+均具有较高稳定性;该分离膜对腐植酸的截留率高达99.0%,且具有优良的抑菌性能,抑菌率高达85.7%.此外,相对于静态浸泡法,动态电沉积法是一种更有效的Cu2+固载手段,不仅大幅缩短了固载时间,还显著提高了Cu2+固载率.     

Small-volume radial flow cell for all-solid-state ion-selective electrodes

A flow cell with a radial distribution of four all-solid-state ion selective electrodes (ISEs), or alternatively three ISEs and one reference electrode, was designed and optimized for mass production. The radial distribution of the electrodes reduces the cell volume and is expected to minimize cross-contamination between different electrodes. Two different cell prototypes were developed and tested for all-solid-state K⁺-ISEs based on a solvent polymeric ion-selective membrane (ISM) and a conducting polymer, poly(3,4-ethylenedioxythiophene), as solid internal contact. In the first prototype, PEDOT was electropolymerized from an aqueous solution of the monomer and the doping ion salt, sodium polystyrenesulfonate (NaPSS). The second prototype employed an aqueous dispersion of PEDOT(PSS) that is commercially available (Baytron P, Bayer AG). Compared to electrochemical synthesis, solution casting of the polymer dispersion was found to be a more advantageous method to deposit the conducting polymer layer aiming at mass production. The resulting prototypes of the flow cell had a small volume (ca. 17-37 μl), which makes them suitable for application in clinical analysis.     

Cu2+对联苯甲醛修饰的树状大分子聚酰胺-胺荧光性能的影响

采用小分子联苯甲醛(BPA)分别修饰第一和第二代树状大分子聚酰胺-胺(PAMAM), 合成了2种PAMAM的修饰产物G1-BPA4和G1-BPA8. 利用IR, 1H NMR及MALDI-TOF MS等手段表征了2种产物的结构, 研究了Cu2+浓度对其荧光性能的影响. 结果表明, 在一定的浓度范围内, 作为常见荧光猝灭剂的Cu2+能使2种产物的荧光均显著增强.     

基于硫氮杂冠醚离子载体的高选择性聚合物膜汞离子选择性电极

以硫氮杂冠醚化合物为离子载体,制备了一种高选择性聚合物膜汞离子选择性电极.通过对电极膜的组成及活化条件进行优化,电极在3.0×10-8～1.0×10-4 mol/L的范围内对汞离子呈能斯特响应,响应斜率为31.2 mV/dec,检出限为2.0×10-8 mol/L.该电极对大多数常见的金属离子具有良好的选择性,并可作为指示电极用于电位滴定.