Cesium-ion selective electrodes based on calix[4]arene dibenzocrown ethers

Four calix[4]arene dibenzocrown ether compounds have been prepared and evaluated as Cs(+)-selective ligands in solvent polymeric membrane electrodes. The ionophores include 25,27-bis(1-propyloxy)calix[4]arene dibenzocrown-6 1, 25,27-bis(1-alkyloxy)calix[4]arene dibenzocrown-7s 2 and 3, and 25,27-bis(1-propyloxy)calix[4]arene dibenzocrown-8 4. For an ion-selective electrode (ISE) based on 1, the linear response concentration range is 1x10(-1) to 1x10(-6) M of Cs(+). Potentiometric selectivities of ISEs based on 1-4 for Cs(+) over other alkali metal cations, alkaline earth metal cations, and NH(4)(+) have been assessed. For 1-ISE, a remarkably high Cs(+)/Na(+) selectivity was observed, the selectivity coefficient (K(Cs,Na)(Pot)) being ca. 10(-5). As the size of crown ether ring is enlarged from crown-6 (1) to crown-7 (2 and 3) to crown-8 (4), the Cs(+) selectivity over other alkali metal cations, such as Na(+) and K(+), is reduced successively. Effects of membrane composition and pH in the aqueous solution upon the electrode properties are also discussed.     

Novel Cesium‐Selective Electrodes Based on Lipophilic 1,3‐Bisbridged Cofacial‐calix[6]crowns

Five bisbridged calix[6]crowns have been investigated as Cs⁺ ionophore in PVC membrane electrodes. As ionophores, three 1,3‐bisbridged calix[6]crown‐4‐ethers( I–III ), 1,3‐bisbridged calix[6]crown‐5‐ether( IV ), and 1,3‐bisbridged calix[6]crown‐6‐ether( V ) have been evaluated. The membranes all give good Nernstian response in the concentration range from 1×10^?7 to 1×10^?1 M of cesium ion. The best detection limits (?log aequation/tex2gif-inf-1.gif=7.08–7.36) are obtained for electrode membranes containing 1,3‐bisbridged cofacial‐calix[6]crown‐4‐ethers( I‐III ), and the values are the lowest compared with those reported previously. The highest selectivity coefficients [ 3.74(Cs/K), 2.63(Cs/Rb)] are obtained for the membrane of 1,3‐bisbridged calix[6]crown‐4‐ether( II ), and these values are also the highest compared with previous reports for Cs⁺‐ISEs. The highest selectivity towards cesium ion is attributed to the geometrically cofacial positions of two crown‐ethers in calix[6]crowns in order to provide the complex of cesium ion and eight oxygens of cofacial crowns.     

新型杯芳烃为载体的铅离子选择电极

报道了5,11,17,23-四（1,1-二甲基乙基）-25,27-二羟基-26,28-二[（2-丙酰胺）乙氧基]杯[4]芳烃1的合成及以此化合物为载体研制了PVC膜铅离子选择电极。研究了不同极性的膜增塑剂和亲脂性阴离子位点对铅离子选择电极响应性能的影响,测定了铅离子选择电极的性能。铅离子选择电极对铅离子表现出优良的能斯特响应和高选择性,能在pH4.0-6.5的范围内使用,该电极可作为电位滴定的指示电极。     

Selective electrodes for silver based on polymeric membranes containing cali

Silver ion-selective electrodes were prepared with polymeric membranes based on two calix[4]arene derivatives functionalized by two hydroxy and two benzothiazolylthioethoxy groups. The electrodes all gave a good Nernstian response of 58mV decade(-1) for silver in the activity range 5 x 10(-6)-10(-1) M, the limits of detection reached 10(-5.8) M and exhibited high selectivity towards alkali, alkaline earth and some transition metal ions. The electrode was used as indicator electrode in titrations of Ag+ with Cl- ion.     

Cesium ion selective electrode based on calix[4]crown ether-ester

The potentiometric response characteristics of cesium ion selective PVC membrane electrode employing calix[4]crown ether-ester as an ionophore were investigated. The electrode exhibit a good response for cesium ion over wide concentration range of 5.0x10(-6)-1.0x10(-1) M with a Nernstian slope of 59 mV per decade. The detection limit of electrode is 5.0x10(-6) M. The electrode was found to have selectivity for cesium ion over alkali, alkaline and transition metals. The response time of the electrode is less than 20 s and can be used for more than 4 months without observing any divergence in potentiometric response. The electrode response was stable over wide pH range.     

Studies on the Synthesis and Property of A New Podand-armed Calix[4]arene Derivative

Pendant groups such as esters, amides, carboxylic acids, etc. have been grafted at thelower rim of call-c[41arene to produce a variety of novel ionophores'. The call-c[4]areneswith different functional groups have showed coordination diversity for alkali metalcanons2. In this paper we described the synthesis of a new calixarene derivative withpodand-armed functional group and the property as ionophore and extractant for cesiumIOn.25, 26, 27, 28-Tetrakis[2-(o-methoxyphenoxy) 3 wassynthesized f…     

Surfactant Ion Selective Membrane Electrodes

Abstract

Calix[8]arene ethers, carboxylic esters having various p-substituents and acid are synthesized and studied. In a bulk membrane transport of dodecylpyridinium the better carrier is the simplest host, calix[8]arene octamethyl ether. Inversely, it is the worst carrier for dodecyltrimethylammonium; the better here is carboxy ester with adamantyl p-substituents. Various calixarenes are successfully used in plasticized membrane ion-selective electrodes (ISE) for both above ammonium and pyridinium surfactants. Operational characteristics, potentiometric selectivity and optimal membrane compositions are reported. Typical limit of detection is at the level of nx10^?6 - 1x10^?5 M, response time 5-10 s, and lifetime is at least 6 months. ISE's selectivity is significantly better than that of ion-association and crown-ether based electrodes.     

Silver(I) ion-selective membrane based on Schiff base-p-tert-butylcalix[4]arene

A PVC membrane electrode for silver(I) ion based on Schiff base-p-tert-butylcalix[4]arene is reported. The electrode works well over a wide range of concentration (1.0 x 10(-5)-1.0 x 10(-1) mol dm-3) with a Nernstian slope of 59.7 mV per decade. The electrode shows a fast response time of 20 s and operates in the pH range 1.0-5.6. The sensor can be used for more than 6 months without any divergence in the potential. The selectivity of the electrode was studied and it was found that the electrode exhibits good selectivity for silver ion over some alkali, alkaline earth and transition metal ions. The silver ion-selective electrode was used as an indicator electrode for the potentiometric titration of silver ion in solution using a standard solution of sodium chloride; a sharp potential change occurs at the end-point. The applicability of the sensor to silver(I) ion measurement in water samples spiked with silver nitrate is illustrated.     

双层夹心膜电极电位法测定溶剂聚合物膜中杯芳烃-金属离子配合物的生成常数

以双层夹心膜电极为指示电极,采用电位法测定了聚合物膜中活性离子载体杯[6]芳烃乙酯与金属离子形成的配合物的生成常数.提出了一种新的测定夹心膜膜电位的方法,由测得的膜电位可计算出配合物的生成常数.以杯[6]芳烃乙酯为离子载体,测得其与Li⁺,Na⁺,K⁺,Cs⁺和NH⁺₄等离子的配合物生成常数的对数值分别为6.14,6.48.6.74,7.43和6.21.制备了以Cs⁺为主离子的选择性电极,采用固定干扰法,测得对Li⁺,Na⁺,K⁺和NH⁺₄等离子的选择性系数的对数值分别为-3.33,-2.54,-1.6和-2.9.实验结果表明,配合物的生成常数与选择性系数之间有较好的相关性.生成常数越大,电极对相应离子的选择性越高.     

Calcium-selective electrode based on a calix[4]arene tetraphosphine oxide

A new ligand capable of producing calcium-selective electrodes with excellent characteristics is presented. The ligand (1) is a calix[4]arene bearing phosphine oxide ligating groups on the lower rim and this is the first report that such ligands can discriminate in favour of calcium ions against magnesium ions and the alkali metal ions. This calcium selectivity is in complete contrast to the behaviour of the well-known calix[4]arene tetraester derivatives (such as 2) which are selective for sodium against other alkali metal ions and group II ions. Electrodes based on PVC membranes incorporating ligand 1 display almost nernstian slopes and excellent selectivity against common interferants, including magnesium (log K(Ca,Mg)(pot)). The electrodes have demonstrated effective lifetimes of at least 7 weeks (duration of the study) and very fast response times.     

Syntheses and Properties of New Pendant‐armed Calix[4]arene Derivatives as Cesium Selective Ionophore

Two new pendant‐armed calix[4]arene derivatives 5 and 6 have been synthesized. The study of alkali metal picrates extraction indicates that both compounds show preference of cesium cation, compound 6 in 1,3‐alternate conformation has better extractibility for Cs⁺ than compound 5. The coordination behavior of compound 6 with cesium cation was studied by ¹H NMR spectroscopy. The Cs⁺ selective electrode based on compound 6 exhibits a linear, near Nernstian response characteristics, the slope is 56.4 mV/decade in me concentration range of 10^?4—10^?1 mol/L, the selectivity coefficient (logK^pot_Cs.Na) is ?3.39.     

Calix[2]furano[2]pyrrole and related compounds as the neutral carrier in silver ion-selective electrode

The performance of calix[2]furano[2]pyrrole and related compounds used as neutral carriers for silver selective polymeric membrane electrode was investigated. The silver ion-selective electrode based on calix[2]furano[2]pyrroles gave a good Nernstian response of 57.1 mV per decade for silver ion in the activity range 1×10⁻⁶ to 1×10⁻² M. The present silver ion-selective electrode displayed very good selectivity for Ag⁺ ion against alkali and alkaline earth metal ions, NH₄⁺, and H⁺. In particular, the present Ag⁺-selective electrode exhibited very low responses towards Hg²⁺ and Pb²⁺ ions. The potentiometric selectivity coefficients of the silver ion-selective electrode exhibited a strong dependence on the solution pH. In particular, the response of the electrode to the Hg²⁺ activity was greatly diminished at pH 2.5 compared to that at pH 5.0. Overall, the performance of the present silver ion-selective electrode based on the ionophore, calix[2]furano[2]pyrrole, is very comparable to that of the electrode prepared with the commercially available neutral carrier in terms of slope, linear range, and detection limits.     

Potassium-selective membrane electrodes based on macrocyclic metacyclophanes analogous to calixarenes.

The tetrabutyl ester derived from 9,16,25,32-tetrahydroxy[3.1.3.1]metacyclophane was an excellent ionophore for constructing a K+-selective membrane electrode. This ionophore exhibited a much higher selectivity toward K+ than the structurally similar potassium ionophore IV commercially available from Fluka. In particular, the interference from organic ammonium ions decreased remarkably. Potassium ionophore IV possessed oxygen atoms in the ring structure, while the present ionophore changed the oxygen atoms to carbon atoms. Thus, the removal of oxygen atoms in ring constituents of the metacyclophane acted to reduce the interaction with the NH3+ group of organic ammonium ions. The size of the cavity of the present ionophore was between those of calix[4]arene and calix[6]arene derivatives, which act as Na+ and Cs+ ionophores, respectively, demonstrating that the ability to recognize alkali metal cations was strongly cavity size-dependent. The present K+-selective electrode had less interference from Rb+ and Cs+ than an electrode constructed using valinomycin, but suffered greater interference from Na+.     

New Calix[4]arene-monobenzo- and -dibenzo-crown-6 as Cesium Selective Ionophores in the Radioactive Waste Treatment: Synthesis, Complexation and Extraction Properties

Cesium possesses two long lived isotopes ¹³⁵Cs and ¹³⁷Cs and the first one has a very long (2.3 × 10⁶ y) half life and is one of the most mobile nuclides in a repository.Calix[4]arene-crowns-6 in the 1,3-alternate conformation areemerging as a new class of ionophores exhibiting a very high efficiency and selectivity in the complexation of cesium ion and itsremoval from highly acidic ([HNO₃] = 3–4 M) radioactive waste having also high sodium nitrate concentration ([NaNO₃] = 2–4 M). In order to improve both efficiency and cesium selectivity we have synthesised the novel calix[4]arene dibenzo-crowns-6 1 and 2 and thecalix[4]arene-monobenzocrown-6 3 in 1,3-alternate conformationand evaluated their complexation properties towards alkali metal cations in homogeneous solution and in two phase systems, togetherwith their performance in radioactive waste treatment. All data confirm the higher Cs/Na selectivity of the 1,3-alternate calix[4]crown-6 1–3 containing aromatic rings in the polyether loop, in comparison to previously synthesised compounds of the same series.     

New cesium ion-selective electrodes based on anilino-(1,3-dioxo-2-indanylidene) acetonitrile derivatives

Cesium ion-selective PVC membrane electrodes based on anilino-(1,3-dioxo-2-indanylidene) acetonitrile derivatives as a novel class of neutral ionophores were examined. The ionophores were p-methoxyanilino-(1,3-dioxo-2-indanylidene) acetonitrile, p-methylanilino-(1,3-dioxo-2-indanylidene) acetonitrile and p-N,N-dimethylanilino-(1,3-dioxo-2-indanylidene) acetonitrile. The anilino-(1,3-dioxo-2-indanylidene) acetonitrile proved to work well with cesium, the corresponding electrodes display a response to this ion. The most favourable ionophore was p-methoxyanilino-(1,3-dioxo-2-indanylidene) acetonitrile, especially when the secondary ion exchanger potassium tetrakis (4-chlorophenyl) borate was incorporated in 2-nitrophenyl octyl ether for ion-selective electrode membrane construction. The response function was linear within the concentration range 10(-1)-2.5x10(-5) mol l(-1) and the slope was 52 mV decade(-1). The detection limit remained at 6.3x10(-6) mol(-1). The selectivity and response time of the electrode was studied and it was found that the electrode exhibited good selectivity for cesium over alkali, alkaline earth and some transition metal ions. The electrode response was stable over a wide pH range. The lifetime of the electrode was about 1 month.     

Selective extraction of Cs(I) using 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene in ionic liquid solvents and its application to the treatment of high-level liquid waste

To separate heat-generating Cs from high-level liquid waste (HLLW), the extraction of Cs(I) using 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (calix[4]arene-R14) in combination with 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) ionic liquids ([C _n mim][NTf₂], where n?=?2, 4, and 6) was investigated. Under moderately acidic conditions, the calix[4]arene-R14/[C _n mim][NTf₂] system showed a higher extraction efficiency (E_Cs) than that exhibited by the conventional calix[4]arene-R14/dichloromethane system. All extraction processes reached equilibrium within 5 min. Slope analysis revealed that the Cs:calix[4]arene-R14 inclusion complex has a 1:1 stoichiometry. The extraction was found to be exothermic and influenced by the presence of Na(I). These extraction systems exhibited high efficiency and selectivity for Cs(I) in simulated HLLW.     

Synthesis of a tweezer-like bis(arylthiaalkoxy)calix[4]arene as a cation sensor for ion-selective electrodes: an investigation of the influence of neighboring halogen atoms on cation selectivity

Two novel tweezer-like 25,27-dihydroxy-26,28-bis(phenylthiaethoxy)calix[4]arenes 6 and 7 were synthesized by the reaction of 25,27-dihydroxy-26,28-bis(bromoethoxy)calix[4]arenes 3 and 4 for the evaluation of their ion-selectivity in ion-selective electrodes (ISEs). X-ray structural analysis indicated that calix[4]arene 7 is in an interesting infinite linear aggregate via self-inclusion. For investigation of the influences of substitutes on the behavior of the ISEs, the halogen substituted aryl analogues of 25,27-dihydroxy-26,28-bis(arylthiaethoxy)calix[4]arenes 8-12 were also synthesized and their ISE performances were evaluated under the same conditions. ISEs based on 6-12 as neutral ionophores were prepared, and their selectivity coefficients for Ag+ (log KAg,M(pot)) were investigated against other alkali metal, alkaline-earth metal, lead, ammonium ions and some transition metal ions using the fixed interference method (FIM). These ISEs showed excellent Ag+ selectivity over most of the interfering cations examined, except for Hg2+ having relative smaller interference (log KAg,Hg(pot) < or = 2.1). The 19F NMR spectra of 9 and 9.AgClO4 were recorded for investigation the fluorine environments in the complex. The 19F NMR spectra strongly suggested that the fluorine atoms on ionophore 9 participated in ligation with silver cation.     

Strontium(II) sensor based on a modified calix[6]arene in PVC matrix.

5,11,17,23,29,35-Hexakis(1,1,3,3-tetramethylbutyl)-37,38,39,40,41,42-hexakis(carboxy methoxy)calix[6]arene (I) has been evaluated as an ionophore for the analysis of Sr2+. The influences of the nature of the plasticizers (DBA, CN, DOP, NPOE) and of the anion excluder (NaTPB) on the characteristics of the electrode were discussed. The best electrode was fabricated with a membrane having composition 6:150:170:3 (I:PVC:DBA:NaTPB). The response to Sr2+ was Nernstian in the range 1.9 x 10(-5) to 1.0 x 10(-1) M of Sr2+. The influence of pH has also been studied. The electrode exhibited better potential stability and had an operational lifetime of 4 months. The K(A,B)(Pot) values showed that other alkaline earth metal ions are well discriminated. The sensor has also been used as an indicator electrode in the potentiometric titration of sodium carbonate with strontium(II) ions.     

Synthesis,structures, and conformational characteristics of calixarene monoanions and dianions

The synthesis, complete characterization, and solid state structural and solution conformation determination of calix[n]arenes (n = 4, 6, 8) is reported. A complete series of X-ray structures of the alkali metal salts of calix[4]arene (HC4) illustrate the great influence of the alkali metal ion on the solid state structure of calixanions (e.g., the Li salt of monoanionic HC4 is a monomer; the Na salt of monoanionic HC4 forms a dimer; and the K, Rb, and Cs salts exist in polymeric forms). Solution NMR spectra of alkali metal salts of monoanionic calix[4]arenes indicate that they have the cone conformation in solution. Variable-temperature NMR spectra of salts HC4.M (M = Li, Na, K, Rb, Cs) show that they possess similar coalescence temperatures, all higher than that of HC4. Due to steric hindrance from tert-butyl groups in the para position of p-tert-butylcalix[4]arene (Bu(t)C4), the alkali metal salts of monoanionic Bu(t)C4 exist in monomeric or dimeric form in the solid state. Calix[6]arene (HC6) and p-tert-butylcalix[6]arene (Bu(t)C6) were treated with a 2:1 molar ratio of M(2)CO(3) (M = K, Rb, Cs) or a 1:1 molar ratio of MOC(CH(3))(3) (M = Li, Na) to give calix[6]arene monoanions, but calix[6]arenes react in a 1:1 molar ratio with M(2)CO(3) (M = K, Rb, Cs) to afford calix[6]arene dianions. Calix[8]arene (HC8) and p-tert-butylcalix[8]arene (Bu(t)()C8) have similar reactivity. The alkali metal salts of monoanionic calix[6]arenes are more conformationally flexible than the alkali metal salts of dianionic calix[6]arenes, which has been shown by their solution NMR spectra. X-ray crystal structures of HC6.Li and HC6.Cs indicate that the size of the alkali metal has some influence on the conformation of calixanions; for example, HC6.Li has a cone-like conformation, and HC6.Cs has a 1,2,3-alternate conformation. The calix[6]arene dianions show roughly the same structural architecture, and the salts tend to form polymeric chains. For most calixarene salts cation-pi arene interactions were observed.     

Molecular design of calixarene-based ion-selective electrodes

In order to obtain insights into relationships between the calix[4]arene structure and the ion selectivity in the electrode system, 20 ionophoric calix[4]arenes were synthesized and their ion selectivity (with Na⁺ as a standard) estimated. Among these ionophoric calix[4]arenes, 25,26,27,28-tetrakis[(ethoxycarbonyl)methoxy]-p-t-octylcalix[4]arene afforded the highest logK _NA,M ^pot value (–3.1) in the presence of 2-fluorophenyl-2-nitrophenylether (10) as the best of 13 plasticizers. This is the first example in which the Na⁺/K⁺ selectivity exceeds a factor of 10³ in the electrode system based on the neutral carrier. The high Na⁺ selectivity is attributed to modification of the upper rim which ostensibly has no relation with the component of the cavity. This paper demonstrates the potential relationships between the unique structure of the calix[4]arene-based ligands and selectivity performance for the design of ion-selective electrodes.