Highly Efficient and Selective Membrane Transport of Silver(I) Using Dibenzodiaza‐15‐Crown‐4 as a Selective Ion Carrier

A chloroform membrane system containing dibenzodiaza‐15‐crown‐4 was found to be a highly efficient and selective transport of Ag⁺ ions through a chloroform liquid membrane. In the presence of thiosulfate ion as a suitable ion stripping agent in the receiving phase, the amount of silver transported across the liquid membrane after 105 minis 95 ± 1.3%. The selectivity of Ag⁺transport from aqueous solutions containing Tl⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, K⁺, Ca²⁺, Sr²⁺, Hg²⁺, Zn²⁺, Cu²⁺was investigated. The interfering effect of Cu²⁺ ions was drastically diminished in the presence of EDTA as a proper masking agent in the source phase.     

A Spectrophotometric Investigation of the Interaction of Iodine with Dibenzyldiaza‐18‐crown‐6, Aza‐15‐crown‐5 and N‐phenylaza‐15‐crown‐5 in Chloroform Solution

The complex formation reactions between iodine and DBzDA18C6, A15C5 and N‐phenylA15C5 have been studied spectrophotometrically in chloroform solution. In the case of DBzDA18C6 is the resulting 1:2 (ligand…I⁺)I₃^?, while, in the case of A15C5 and N‐phenylA15C5 a 2:2 molecular complex of [(ligand)₂…I⁺]I₃^? type was formed. The spectrophotometric results indicate that gradual release of triiodide ion from its contact ion paired form in the molecular complex into the solution is the rate‐determining step of the reaction. The kinetic rate constants for the complexation reactions were determined at different temperatures, and activation parameters were calculated from Arrhenius and Eyring equations.     

Preparation and Application of Cholesteryl‐Benzo‐15‐Crown‐5/Cholesteryl Mixed Liquid Crystals

Various mixed liquid crystals containing crown ether‐cholesteryl liquid crystal, benzo‐15‐crown‐5‐COO‐C₂₇H₄₅ (B15C5‐COOCh), with various common cholesteric liquid crystals, e.g., cholesteryl chloride, cholesteryl benzoate and cholesteryl palmitate, were prepared and studied using polarizing microscopy and differential scanning calorimetry. Investigating the concentration effect of B15C5‐COOCh in mixed liquid crystals revealed that the addition of B15C5‐COOCh resulted in wider phase transition temperature ranges of these cholesteryl liquid crystals. The stability of these B15C5‐COOCh/cholesteryl mixed liquid crystals was studied using comprehensive graphic molecular modeling computer programs (Insight II and Discover) to calculate their molecular energy and stability energy. The effect of salts, e.g. Na⁺, Co³⁺, Y³⁺ and La³⁺, on the transition temperature range of the mixed liquid crystals was also investigated. The crown ether cholesteric liquid crystal B15C5‐COOCh was applied both as a surfactant and an ion transport carrier to transport metal ions through liquid membranes. Cholesteryl benzo‐15‐crown‐5 exhibited distinctive characteristics of a surfactant and the critical micellar concentration (CMC) of the surfactant was investigated by the pyrene fluorescence probe method. Cholesteryl benzo‐15‐crown‐5 was successfully applied as a good ion transport carrier (Ionophore) to transport various metal ions, e.g. Li⁺, Na⁺, La³⁺, Fe³⁺ and Co³⁺, through organic liquid membranes. The transport ability of the cholesteryl benzo‐15‐crown‐5 surfactant for these metal ions was in the order: Co³⁺ ≥ Li⁺ > Fe³⁺ > Na⁺ > La³⁺.     

Triiodide PVC Membrane Electrode Based on a Charge‐Transfer Complex of Iodine with Ditertbutyl‐Dicyclohexyl‐18‐Crown‐6

A new triiodide ion‐selective electrode based on a charge‐transfer complex of iodine with ditertbutyl‐dicyclohexyl‐18‐crown‐6 (t‐Bu)₂DC18C6 as membrane carrier was prepared. The electrode has a linear dynamic range from 6.3 × 10^?3‐5 × 10^?6 with a Nernstian response of 58.6 ± 1 mV decade^?1 and a detection limit of 1.3 × 10^?6 M. The response time of the sensor was 25 s. The membrane could be used for two months without any divergence in potentials. The electrode exhibits an anti‐Hofmeistetr selectivity sequence with a preference for triiodide at pH 2.0‐10.0. The response mechanism of the electrode was investigated by Uv‐Vis spectroscopic technique. The electrode can be used for the determination of ascorbic acid in orange juice.     

Specific Uphill Transport of Zinc as Zn(SCN)42− Ion using Na+-Dicyclohexyl-18-Crown-6 as Carrier

Sodium-dicyclohexyl- 18-crown-6 complex cation was used as carrier for the uphill transport of zinc as Zn(SCN)₄^2? complex anion. By using L-cysteine as a metal ion acceptor in the receiving phase at the optimized pH of 7.6, the amount of zinc transport through the liquid membrane after 90 min was 97.2 ± 1.0%. The selectivity and efficiency of zinc transport from aqueous solutions containing equimolar mixtures of Ag⁺, Cd²⁺ Co²⁺, Cu²⁺, Fe²⁺, Ni²⁺, Pb²⁺, Pd²⁺, Sr²⁺, Bi³⁺, Cr³⁺ and Fe³⁺ ions was investigated. In the presence of NH₂OH.HCl as a suitable masking agent in the source phase, the interfering effect of Cu²⁺ and Pb²⁺ ions was diminished drastically.     

Selective Transport of Lead(II) and Strontium(II) Through a Crown Ether-Based Polymer Inclusion Membrane Containing Dialkylnaphthalenesulfonic Acid

New polymer inclusion membranes (PIMs) containing 18-membered crownethers and dialkylnaphthalenesulfonic acid are proposed for Sr2+ and Pb2+removal from nitric acid solutions. The influence of source phasecomposition and stripping agents was characterized and permeabilitycoefficients were calculated. The PIMs are easy to prepare and may be usefulin separation and concentration procedures for these cations from complexmixtures such as nuclear waste. Long-term stability was obtained for atleast several weeks of constant use during which no significant change ofpermeability was observed.     

Kinetic Study of Mercury(II) Transport through a Bulk Liquid Membrane Using Cyanex 301 as Carrier

A kinetic study of Hg(II) ions transport through a bulk liquid membrane (BLM) was investigated. The commercially available liquid bis(2,4,4‐trimethyl(pentyl) dithiophosphinic acid) (Cyanex 301) was employed as mobile carrier. The influences of the carrier concentration in the liquid membrane, HNO₃ concentration in the feed phase, type of organic solvent, composition of the receiving phase, and stirring speed on mass transfer were studied. Various solvents including CH₂Cl₂, CHCl₃, C₂H₄Cl₂ and CCl₄ were used as organic membrane. Among the solvents, CHCl₃ provided the superior results. The kinetic parameters (k₁, k₂, R_m^max, t^max, J_d^max, and J_a^max) were calculated for the interface reaction assuming two consecutive, irreversible first‐order reactions. The analysis of Hg(II) accumulation in liquid membrane and the rate‐controlling step under different experimental conditions were elucidated. The experiments demonstrated that Cyanex 301 is an appropriate carrier for Hg(II) transport through liquid membrane.     

Be(II) Graphite Coated Membrane Sensor Based on a Recently Synthesized Benzo‐9‐Crown‐3 Derivative

A highly sensitive and selective membrane electrode with 9‐crown‐3 derivative (CD) as ionophore, potassium tetrakis‐(p‐chlorophenyl) borate as anionic additive (KTB), acetophenone (AP) as solvent mediator was prepared and investigated as a Be(II) sensor. The best performance was observed with the membrane having the percent ratio 30% PVC: 8% CD: 6% KTB: 56% Acetophenone. The poly(vinyl chloride) PVC membrane containing 9‐crown‐3 derivative (CD) directly coated on a graphite electrode, shows a Nernstian response for Be(II) ions over a very wide concentration range (1.0×10^?1?1.0×10^?7 M) with a detection limit of 8.0×10^?8 M (ca. 0.72 ng/mL). It has a fast response time of ca. 20 s and can be used for at least 10 weeks without any major deviation in potential. The proposed sensor exhibits very good selectivity with respect to common alkali, alkaline earth, transition and heavy metal ions. The proposed sensor was used as end point indicator electrode in the titration of Be(II) ions with EDTA. It was also applied to determination of Be(II) in real sample.     

Two—dimensional Network Crown Ether Complex.Synthesis and Crystal Structure of 18—Crown—6 Complex：[K（18—C—6）]2[Cd—（nmt）2]

The novel complex [K(18-C-6)]2[Cd(mnt)2][18-C-6-18-crown-6,nmt=1,2-dicyanoethene-1,2-dithiolate,C2S2-(CN)2^2-] was synthesized and characterized by elemental analysis,IR spectrum and X-ray diffraction analysis.The complex displays two-dimensional network structure of [K(18-C-6)] complex segments and [Cd(nmt)2] complex segment bridged by S-K-S,S-K-N and N-K-N interactions between adjacent[K(18-C-6)] and [Cd(mnt)2]units.     

Isolated Triiodide and Pentaiodide Anions in the Crystal Structure of [Rb(Dibenzopyridino‐18‐Crown‐6)2]2(I3)(I5)

Red shiny crystals of [Rb(dibenzopyridino‐18‐crown‐6)₂]₂(I₃)(I₅) were obtained from a dichloromethane/ethanol solution of RbI, I₂ and dibenzopyridino‐18‐crown‐6. Triclinic, , a = 1494.3(1), b = 1534.1(1), c = 2412.9(2) pm, α = 76.95(1), β = 83.58(1), γ = 68.67(1)°, V = 5016.7(7) 10⁶·pm³, Z = 2. The crystal structure consists of [Rb(dbp18c6)₂]⁺ cations leaving suitable three‐dimensional channels for the linear I₃⁻ and V‐shaped I₅⁻ anions which are isolated from each other.     

苯酚在N-503/煤油支撑液膜体系中的传输分离

研究了以多孔聚丙烯膜为支撑体,N,N′-二(1-甲基庚基)乙酰胺(N-503)为膜流动载体的苯酚支撑液膜传输行为;用液-液萃取法测定了N-503/煤油体系中苯酚萃合物组成为1∶1,及在相应的条件下萃取常数Ke′x为53.7;考察了料液相的pH值、载体浓度、实验温度、起始浓度以及解析相NaOH的浓度对苯酚传输的影响,并对该体系分离、传输苯酚的最佳条件进行了讨论;从界面化学和扩散传质角度提出了苯酚的传输动力学方程,采用直线斜率法对苯酚在N-503/煤油支撑液膜体系中的扩散层厚度和膜内扩散系数进行了测定,取得满意结果。     

Alkali Cation Ligating Chains and Sheets of the Macrocycle 1, 7‐Dithia‐18‐Crown‐6 with Bridging Iodo‐ and Thiocyanatocuprate(I) Units

Treatment of an acetonitrile solution of CuI with 1, 7‐dithia‐18‐crown‐6 (1, 7‐DT18C6) at 100°C affords the coordination polymer ¹[(CuI)₂(1, 7‐DT18C6)₂] ( 1 ) in which 1, 7‐DT18C6 ligands bridge (CuI)₂ rings into double chains. 1D polymers of the type ¹[M{(Cu₃I₄)(1, 7‐DT18C6)}] (M = K, 2 ; M = Cs, 3 ) can be isolated under similar conditions in the presence of respectively KI and CsI. Both contain bridging heptacyclic [Cu₆I₈]^2— units but crystallise in different space groups, namely P1 and C2/m. The cesium cation of 3 is markedly displaced from the best plane through the thiacrown ether donor atoms. Reaction of 1, 7‐DT18C6 with CuSCN in the presence of NaSCN yields ²[{Na(CH₃CN)₂} {(CuSCN)₂(1, 7‐DT18C6)}][Cu(SCN)₂] ( 4 ), in which ¹[(CuSCN)₂] double chains are linked through macrocycles into sheets. Infinite ¹[{Cu(SCN)₂}^—] chains compensate the charge of the Na⁺ cations. Complex 1 can imbibe 0.90 mol CsNO₃ per mol of 1, 7‐DT18C6 pairs.     

Study of the Complexation of Pb(II) with meso‐2,3‐ Dimercaptosuccinic Acid (DMSA) and 2,3‐Dimercapto‐1‐propanesulfonic acid (DMPS) Using a Bismuth‐Bulk Rotating Disk Electrode

For the first time, the suitability of bismuth bulk rotating disk electrode (BiB‐RDE) for the study of metal complexation has been tested. Cyclic (CV) and differential pulse (DPV) voltammetry have been used to study the complexation of Pb(II) with two of the most effective chelating agents for the treatment of Pb(II) poisoning (meso‐2,3‐dimercaptosuccinic acid, DMSA, and 2,3‐dimercapto‐1‐propanesulfonic acid, DMPS). Multivariate curve resolution has been applied to voltammetric data to obtain the stoichiometries and stability constants of the complexes formed. In both systems, the ML₂ complex was predominant, with log β₂ values of 10.13 and 8.80 for DMSA‐Pb(II) and DMPS‐Pb(II), respectively.     

A Study on Complexation and Transport of Cr(III) Through a Chromogenic Aza Crown Liquid Membrane

A new chromogenic aza-crown-ether N-(8-hydroxyquinoline-7-methylene)-4-azadibenzo-18-crown-6-ether (HQMADCE) was synthesized through the condensation reaction of 4-azadibenzo-18-crown-6-ether, 8-hydroxy quinoline and formaldehyde. The synthesized chromogenic crown was characterized by various spectroscopic techniques and its complexation with Cr(III) was studied. The parameters like extraction constant (K_ex), stability constant (β), free energy change (ΔG), enthalpy change (ΔH) and change in entropy (ΔS) were calculated. Subsequently transport of Cr(III) through a bulk liquid membrane containing HQMADCE as carrier was studied. The permeation of metal was investigated as a function of various experimental variables viz. pH, carrier concentration, metal concentration and time. Furthermore, interference by other ions was also studied.     

Complexation of Syndiotactic Polystyrene with 12‐Crown‐4

Solid‐state complexation of syndiotactic polystyrene (sPS) with a crown ether compound, 1,4,7,10‐tetraoxa‐cyclododecane (12‐crown‐4), took place when a film of sPS/chloroform clathrate was subjected to a guest exchange procedure assisted with a plasticizing agent. The new guest 12‐crown‐4 molecules were incorporated into the crystalline region of the sPS film, without causing a large conformational change of host sPS helices. X‐ray diffraction and thermogravimetric investigations showed that sPS/12‐crown‐4 complex had a clathrate complex structure which contained four 12‐crown‐4 molecules per unit cell. IR and Raman data suggested that 12‐crown‐4 took a C_i‐type conformation in the sPS complex phase.

     

Chemischer Transport fester Lösungen. 9 [1] Zum Chemischen Transport fester Lösungen in den Systemen Eisen(II)/Cobalt(II)‐ und Mangan(II)/Cobalt(II)‐germanat

Metagerma‐Chemical Vapor Transport of Solid Solutions. 9. The Chemical Vapor Transport of Solid Solutions in the System Iron(II)/(Cobalt(II)‐and Manganese(II)/Cobalt(II) Germanate By means of chemical vapor transport methods (900 → 700 °C) using HCl as transport agent FeGeO₃, Fe₂GeO₄ and MnGeO₃ have been prepared. Co₂GeO₄ and Fe₂GeO₄ as well as CoGeO₃ and FeGeO₃ form continuous crystalline solid solutions, whereas in MnO/CoO/GeO₂ two different phases (Mn_xCo_1‐x)GeO₃ are formed. All of these systems show congruent transport behaviour. Chemical vapor transport has been proved a suitable method to prepare solid solutions.     

载体乳化液膜法同步进行亚稳相PbCrO4纳米粒子的仿生合成与铅铬废水的处理

采用一种新型的纳米材料仿生合成方法——载体乳化液膜法,在煤油-Span-80-N7301乳化液膜体系中,以电镀废水中常见的Cr(Ⅵ)溶液为外相,蓄电池、油漆等行业废水常见的Pb(Ⅱ)溶液为内相,通过对生物体内囊泡结构的形态和离子传输功能模拟,室温下成功合成了能稳定存在的直径为5～15nm的正交亚稳相PbCrO4纳米粒子．使用XRD,TEM对产物结构和形貌进行了表征．首次通过FT-IR和UV-vis对所得产物和普通块体材料的光学性质做了比较．并对乳化液膜体系控制产物晶型和尺寸的机理进行了初步的探讨．此方法也有望用于对不同类型工业废水的耦合处理．     

Phosphorylation‐Responsive Membrane Transport of Peptides

Phosphorylation and dephosphorylation of peptides by kinases and phosphatases is essential for signal transduction in biological systems, and many diseases involve abnormal activities of these enzymes. Herein, we introduce amphiphilic calixarenes as key components for supramolecular, phosphorylation‐responsive membrane transport systems. Dye‐efflux experiments with liposomes demonstrated that calixarenes are highly active counterion activators for established cell‐penetrating peptides, with EC₅₀ values in the low nanomolar range. We have now found that they can even activate membrane transport of short peptide substrates for kinases involved in signal transduction, whereas the respective phosphorylated products are much less efficiently transported. This allows regulation of membrane transport activity by protein kinase A (PKA) and protein kinase C (PKC), as well as monitoring of their activity in a label‐free kinase assay.     

HPLC of fluoroquinolone antibacterials using chiral stationary phase based on enantiomeric (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6

A residual silanol group‐protecting chiral stationary phase (CSP) based on optically active (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6 was successfully applied to the resolution of fluoroquinolone compounds including gemifloxacin mesylate. The chiral recognition ability of the residual silanol group‐protecting CSP was generally greater than that of the residual silanol group‐containing CSP. From these results, it was concluded that the simple protection of the residual silanol groups of the latter CSP with lipophilic n‐octyl groups can improve its chiral recognition ability for the resolution of racemic fluoroquinolone compounds. The chromatographic resolution behaviors were investigated as a function of the content and type of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature. Especially, the addition of ammonium acetate to the mobile phase was found to be a quite effective means of reducing the enantiomer retentions without sacrificing the chiral recognition efficiency of the CSP.     

Chemischer Transport fester Lösungen. 8 [1] Zum Chemischen Transport von ternären und quaternären Cobalt(II)‐ und Nickel(II)‐germanaten

Chemical Vapor Transport of Solid Solutions. 8 The Chemical Vapor Transport of Ternary and Quarternary Cobalt and Nickel Germanates By means of chemical vapor transport methods using HCl as transport agent CoGeO₃, Co₂GeO₄, and Ni₂GeO₄ have been prepared (1000 → 900 °C and 900 → 700 °C). In this system the formation of a continuous crystalline solid solution of Co₂GeO₄ and Ni₂GeO₄ was found as well as the deposition of the compound NiGeO₃ which — although unknown as a pure solid — can be stabilized as a mixed crystal Ni_xCo_1—xGeO₃ (0 < x < 0, 6).