硫杂冠醚对Ag(I)和Tl(I)的萃取

基于冠醚的配位化学及软硬酸碱理论,设计并合成了五种硫杂冠醚,系统研究了其对Ag(I)和Tl(I)两种软酸离子的络合能力.模拟计算结果表明,五种冠醚与Ag(I)和Tl(I)络合后构型均发生了转变,且结构优化后的五种冠醚与Ag(I)络合过程的ΔG和ΔU均较负,表现出了一定的配位能力,而与Tl(I)络合过程的ΔG和ΔU均接近...     

Viscosity studies of crown ether-containing polymers in solutions of alkali salts. Intra- versus intermolecular crown-cation complexes

The complexation of cations to poly(vinylbenzocrown ethers) strongly affects the viscosity of the polymers. In mixtures of THF-MeOH the reduced viscosities of the polymer-salt solutions at constant polymer concentration pass through a maximum, their values depending on the cation-to-crown ratio and the binding constant of the cations to the poly(crown ethers). Crosslinking and abnormally high viscosities are found when a cation can complex simultaneously with two crown ligands, e.g. in mixtures of potassium salts with styrene copolymers containing pendent benzo-15-crown-5 moieties. In such systems competition exists between the formation of inter- and intramolecular 2:1 crown-cation complexes, and their relative importance depends on the crown content of the copolymer. Spectrophotometric measurements in THF mixtures of styrene-vinylbenzo-15-crown-5 copolymers and potassium picrate reveal that at low crown concentration, intramolecular complexes can form when crown ligands are separated, on the average, by less than four styrene units. The data, in combination with calculations on the distribution of crown ligands along a chain as a function of crown content, can be used to rationalize the viscosity behaviour of these polymer solutions.     

Synthesis and fluorescence of crown ethers containing coumarin

The syntheses and fluorescence properties of a series of novel crown ethers containing coumarin group are presented. 2-(Benzocourmarin-3-acyloxymethyl) crown ethers were synthesized by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 2-hydroxymethyl crown ethers, while 4′-(benzocourmarin-3-carboxamido) benzo crown ethers were secured by reacting the acyl chloride of benzocourmarin-3-carboxylic acid with 4′-aminobenzo crown ethers. Only the ester-type crown ethers were fluorescent. As the polarity of the solvent increased, the emission maximum λ_em showed a slight red shift. DMSO was used as the fluorescence quenching solvent. Increased fluorescence was observed upon the addition of alkali and alkaline earth metal ions.     

SELECTIVITY IN SOLVENT EXTRACTION OF METAL IONS BY ORGANIC CATION EXCHANGERS SYNERGIZED BY MACROCYCLES: FACTORS RELATING TO MACROCYCLE SIZE AND STRUCTURE

Crown ethers and related macrocycles strongly synergize the extraction (phase transfer) of certain metal Ions from aqueous nitrate solutions to toluene solutions of organophilic sulfonic, phosphoric, and carboxylic acids. For alkali metals, the degree of synergism is related to the size correspondence between the macrocycle cavity and the metal ion if macrocycles of similar type and substitution are considered. Alkaline earth metals are similarly strongly synergized but the size-correspondence relationship is less pronounced. Other factors seem to affect selectivity of these elements. Terr.-butylbenzo-substituted crown ethers of the same size are much less effective synergists for the alkaline earths than cyclohexano- or rerr.-butylcyclohexano-substituted compounds. However, with synergism in alkali metal extraction, the reverse is generally true; that is, ferf-butylbenzo-substituted crown ethers are better synergists than cyclohexano-substituted crown ethers. Effects involving the electron-withdrawing influence of the aromatic substituents and the flexibility of the ring may explain this selectivity reversal. The extraction of the divalent first-row transition metals, iron, cobalt, and nickel, is not synergized by any of the macrocycles. However, manganese and zinc with half and completely filled d-shells are synergized suggesting a possible correlation of synergistic coordination effects with ligand field stabilization in the first-row transition elements. Studies to determine the stoichiometry of the organic-phase complexes indicate a single crown ether associated with each molecule of the metal salt of the organic-phase acid. In some cases neutral organic acid molecules may also be associated with the complex.     

新型冠醚及其超分子配合物研究的新进展

介绍了冠醚化学的产生、发展及应用,详细介绍了：几种新型臂式冠醚及其超分子金属配合物的合成;取代冠醚及其金属配合物的合成及应用;新型氮杂冠醚及其金属配合物的合成及应用。并对冠醚化学的发展进行了展望。     

Silver complexes with large crown ethers in propylene carbonate

The complex formation between large crown ethers – e.g. dibenzo-30-crown-10 – and Ag⁺ in propylene carbonate has been studied using potentiometric and calorimetric titrations. The values of the reaction enthalpies with larger crown ethers than 18-crown-6 especially with dibenzo-30-crown-10 indicate that more than six donor atoms are taking part in the interaction with the complexed cation. The values of the reaction entropies of the largest crown ethers examined indicate the high sterical requirements of the complex formation. Obviously large crown ethers are able to encapsulate the complexed cation. The effectiveness of the encapsulation however depends upon the ring size and flexibility of the crown ethers.     

Oxidation of methylphenyl sulfide with hydrogen peroxide in the presence of crown ethers and their complexes with amino acids

The oxidation of methylphenyl sulfide, benzothiophene, and dibenzothiophene with hydrogen peroxide in the presence of crown ethers was studied. The major product of the oxidation was methylphenyl sulfoxide. The reaction was retarded by the addition of amino acids, which formed 1: 1 complexes with the crown ethers. The oxidation of the diesel fraction with hydrogen peroxide can decrease the sulfur content in it.     

Studies of the Size-Selective Extraction of Alkali Metal Ions by the Synergistic Extraction System,Crown Ether-DI(2-Ethylhexyl) Phosphoric Acid-Benzene

Abstract

In order to take practical advantage of the size-selective cation-coordinating ability of the cyclic polyethers (crown ethers), experiments seeking a means of avoiding the problem of solubilizing a mineral-acid anion in a nonpolar organic diluent were performed. Mixtures of several known extractants and crown ethers were tried. Results presented indicate that organic soluble cation exchangers mixed in solution with crown ethers produce a synergistic extractant mixture that largely exhibits the size-selective properties expected of the crown ether. Data are presented for the extraction of macro concentrations of alkali metals by di(2-ethylhexyl) phosphoric acid—dicyclohexyl-18-crown-6 mixtures at a single pH, and at nonloading condition(σ metal cone < 0.04 M) as a function of pH, 2 to 6. In both cases potassium is synergized most strongly presumably because of its best fit to the crown ether cavity. Other data indicate, however, that the size-fit principle is not as consistent for all alkali metal ions and crown ethers as for potassium and dicyclohexyl-18-crown-6. Other effects such as competition for ion hydration and aqueous-phase distribution of the complex may have important effects that have not been elucidated.     

Benzo condensed crown ethers containing 1,8-naphthyridine or 4-pyridone units – synthesis and complex formation with organic guest molecules

New crown compounds 3–5 comprising beside ophenylene groups 1,8-naphthyridine or 4-pyridone groups as characteristic building units are synthesized. They form numerous stoichiometric crystalline complexes with uncharged organic molecules including alcohols, nitro compounds and other dipolar-aprotic solvents, as well as cyclic ethers and aromatic hydrocarbons. Properties of complex formation and host-guest stoichiometries are discussed making a comparison with parent host analogues.     

LUMINESCENCE STUDY OF Eu( III) COMPLEXES EXTRACTED IN THE ORGANIC PHASE

Luminescence lifetimes have been measured for Eu(III) extracted into benzene solutions. The extrac-tants were HDEHP, HTTA, and mixtures of HTTA with crown ethers, TBP, and TOPO. The results were consistent with no residual hydration for Eu(DEHP)₃, and three molecules of hydration for Eu(TTA) ₃,. The Eu(TTA) ₃,-(TOPO)? _n (n = 1,2) complexes have one water molecule or less. The hydration numbers from the luminescence lifetimes compare well with the values from Karl Fischer titrations. The hydration of the crown ether complexes can be related to the degree of steric hindrance by the aliphatic or aromatic groups attached to the crown ethers.     

Chemical modification of chitosan: Synthesis and characterization of chitosan‐crown ethers

Four novel Schiff‐type chitosan (CTS)‐crown ethers were synthesized through a reaction between ? NH₂ in CTS or crosslinked chitosan (CCTS) and ? CHO in 4′‐formylbenzo‐crown ethers, and four secondary‐amino‐type CTS‐crown ethers were prepared through the reduced reaction of NaBH₄, respectively. Their structures were characterized by elemental analysis, Fourier transform infrared (FTIR) spectra analysis, solid‐state ¹³C‐NMR analysis, and X‐ray diffraction (XRD) analysis. The elemental analysis results showed that the percentage of nitrogen in all CTS‐crown ethers were lower than that of CTS or CCTS. From the FTIR data of CTS, CCTS, and CTS‐crown ethers I–VIII, we saw that the characteristic peaks of C?N, N? H, and Ar appeared and that the characteristic peaks of pyranoside in the chain of CTS or CCTS were not destroyed. The XRD spectra demonstrated that CTS‐crown ethers I–VIII gave lower crystallinities than CTS or CCTS, which indicated that these compounds were considerably more amorphous than CTS or CCTS. In the solid‐state ¹³C‐NMR spectra, all of these CTS‐crown ethers had a particular peak of aromatic at 128 or 129 ppm, and the greatest difference between Schiff‐type CTS‐crown ethers and secondary‐amino‐type CTS‐crown ethers was that the Schiff‐type CTS‐crown ethers had the particular peak of C?N, which disappeared in secondary‐type CTS‐crown ethers. All these facts confirmed that the structures of CTS‐crown ethers I–VIII were as expected. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2221–2225, 2003     

Ligands for selective metal ion extraction: A molecular modeling approach

We present a density functional theory (DFT) based study on interaction of alkali metal cations (Li⁺ and Na⁺) with macrocyclic crown ethers of different ring sizes. The minimum energy structures, binding energies, and binding enthalpies of crown ether–cation complexes have been determined with a correlated hybrid density functional, namely Becke’s three-parameter functional, B3LYP using a split valence basis function, 6-311++G(d, p). Geometry optimizations for all the crown ether–cation complexes were carried out with several initial guess structures based on semi-empirical PM3 optimized results. For both metal ions, the calculated values of binding energy and binding enthalpy increase with the increase in size of the crown ether ring, i.e. with the increase in the number of donor oxygen atoms in crown ether. The calculated values of gas phase binding energy for lithium ions are always higher than those for sodium ions in the case of all macrocyclic crown ethers studied at present. The calculated values of binding enthalpy are in good agreement with the reported experimental data.     

Effect of Crown Ethers on Sr2+, Ba2+, and Ra2+ Uptake by Tunnel‐Structure Ion Exchangers

Abstract

The effect of 15‐crown‐5 and 18‐crown‐6 ethers on the uptake of alkaline earth cations by tunnel‐structure ion exchangers polyantimonic acid (PAA) and cryptomelane manganese dioxide (CMD) was examined. In the case of PAA, 15‐crown‐5 and especially 18‐crown‐6 strongly influence the uptake of Sr²⁺ vs Ba²⁺ and Ra²⁺. For separation of the Ra²⁺‐Ba²⁺ pair, the effect of the crown ethers is insignificant. In CMD a small difference in complex formation between crown ethers and Ba²⁺ and Ra²⁺ gives an increase of separation. This effect is observed especially in 15‐crown‐5 solutions.     

RADIUM SEPARATION THROUGH COMPLEXATION BY AQUEOUS CROWN ETHERS AND ION EXCHANGE OR SOLVENT EXTRACTION

ABSTRACT

The effect of three water-soluble, unsubstituted crown ethers (15-crown-5 (15C5), 18-crown-6 (18C6) and 21-erown-7 (21C7) on the uptake of Ca, Sr, Ba and Ra cations by a sulfonic acid cation exchange resin, and on the extraction of the same cations by xylene solutions of dinonylnaphthalenesulfonic acid (HDNNS) from aqueous hydrochloric acid solutions has been investigated. The crown ethers enhance the sorption of the larger cations by the ion exchange resin, thereby improving the resin selectivity over calcium, a result of a synergistic interaction between the crown ether and the ionic functional groups of the resin. Similarly, the extraction of the larger alkaline earth cations into. xylene by HDNNS is strongly synergized by the presence of the crown ethers in the aqueous phase. Promising results for intra-Group IIa cation separations have been obtained using each of the three crown ethers as the aqueous ligands and the sulfonic acid cation exchange resin. Even greater separation factors for the radium - calcium couple have been measured with the crown-ethers and HDNNS solutions in the solvent extraction mode. The application of the uptake and extraction results to the development of radium separation schemes it discussed and a possible flowchart for the determination of ²²⁶Ra/²²⁸Ra in natural waters is presented.

     

Complexes of chitosan and poly(methacrylic acid) studied by fluorescence techniques

Summary Fluorescence techniques have been used to study the interactions of poly(methacrylic acid) (PMAA) with chitosan(CS) in aqueous solution. These studies show that PMAA and CS form complexes within a pH range of 3 to 10 and along with complexing with CS, the conformation of PMAA at pH 4 changed from a hypercoiled to a loose coiled form. However, this conformational change is not complete since the optimal ratio for the complex formation is 0.5:1(CS:PMAA, in residue unit). PMAA/CS complexes at pH 4 were largely disrupted with the addition of NaCl, most likely due to screening of the electrostatic attraction between ionized carboxyl groups of PMAA and protonated amino groups of CS. Received: 23 August 1999/Revised version: 24 September 1999/Accepted: 30 September 1999     

Stoichiometry and Structure of the Complexes Between Lanthanide Ions and Macrocyclic Crown Ethers Containing from Four to Seven Coordinating Sites

The factors influencing the stoichiometry and the structure of the complexes between trivalent lanthanide perchlorates, hexafluorophosphates, nitrates, trifluoroacetates, chlorides, bromides, isothiocyanates and the polyethers 12-crown-4, 15-crown-5, 18-crown-6, dibenzo-18-crown-6 and 21-crown-7 are reviewed. The properties of divalent lanthanide and Ce(IV) complexes with crown ethers are presented and discussed.     

异羟肟酸过渡金属络合物在乙苯氧化中的催化性能研究

研究了 N-苯甲酰 -N-苯基羟胺 ( BPHA)类过渡金属络合物在乙苯均相氧化中的催化行为 ,考察了络合物催化剂中心金属离子、配体结构以及添加助剂对络合物催化性能的影响 ,并找到了催化剂、助剂的最佳使用浓度及氧化反应的最适宜温度。结果表明 ,中心金属离子的电子结构对络合物催化性能影响最大 ,其活性顺序为 :Cu( BPHA) 2 >Co( BPHA) 2 >Fe( BPHA) 2>Mn( BPHA) 2 >Ni( BPHA) 2 ,配体结构对催化性能有一定影响 ,配体的芳环上有吸电子基团时 ,催化剂分解氢过氧化物的能力增加 ,主要分解产物为苯乙酮。添加轴配体对氧化反应及催化剂的选择性有较大影响 ,其中含端羟基的非环冠醚类及大环冠醚对氢过氧化物的生成和分解都有加速作用 ,含氮助剂吡啶对氧化反应有抑制作用     

Flüssig-Flüssig-Extraktion von Metallionen mit Lariatethern

Liquid-Liquid-Extraction of Metal Ions with Lariat Ethers . Lariat ethers of various ring size and substitution are synthesized and characterized by physical data and chemical analysis. The extraction behaviour of the crown compounds towards Na⁺, K⁺, Cs⁺ and Ag⁺ in a picric acid solution has been investigated. The extraction contants for 1:1 and 1:2 complexes are determined using the equilibrium distribution data. The results show that the flexible side chain in the investigated compounds has in no case a positive effect on the metal picrate extraction.     

Study of transition metal complexes as curing accelerators for anaerobic adhesives

Reported are the results of studying the influence of the composition of the complexes of transition metal salts with crown ethers on the kinetics of the curing of anaerobic adhesives developed in Kargin Research Institute of Polymer Chemistry and Technology. It is established that the use of copper salts makes it possible to substantially decrease the setting time on zinc-coated surfaces; however, in this case, the working life of adhesive decreases abruptly. It is shown that the activity of salts can be decreased by their complexation with various chelating agents. It is revealed that transition metal salts in the form of complexes with some crown ethers not only increase the rate of curing of anaerobic adhesives, but also considerably enhance the thermal stability of cured products that is explained by the ability of organic salts of metals to the inhibition of thermal-oxidative degradation of polymers.