Crown ethers at the aqueous solution-air interface: 1. Assignments and surface spectroscopy

The surface of aqueous solutions of 4-Nitro Benzo-15-Crown-5 (NB15C5) and Benzo-15-Crown-5 (B15C5) has been studied using the surface sensitive technique vibrational sum frequency spectroscopy (VSFS). The NO, CN, COC and CH vibrational modes of these compounds at the air-water interface as well as OH vibrational modes of the surface water hydrating this compound have been targeted in order to obtain molecular information about arrangement and conformation of the adsorbed crown ether molecules at the air-water interface. The CH(2) vibrational modes of crown ethers have been identified and found to be split due to interaction with ether oxygen. The spectra provide evidence for the existence of a protonated crown complex moiety at the surface leading to the appearance of strongly ordered water species. The interfacial water species are influenced by the resulting charged interface and by the strong Zundel polarizability due to tunneling of the proton species between equivalent sites within the crown ring.     

镉－硫氰酸根与铵－苯并15－冠－5配合物的合成与结构研究

用凝胶法生长了标题配合物［ＮＨ_４（Ｂ１５Ｃ５）_２］［Ｃｄ（ＳＣＮ）_３］的晶体，并对其进行了红外光谱，元素分析等各项物理性质的测试。经Ｘ射线单晶结构分析得到了配合物的全部晶体学数据：Ｍ_ｒ＝８４１．３１，正交晶系，空间群Ｐ２_１２_１２_１，晶胞常数ａ＝１０．９７０（３），ｂ＝２１．８３４（３），ｃ＝１５．５６３（４），Ｖ＝３７２７（３），Ｚ＝４，Ｄ_ｘ＝１．５０ｇ／ｃｍ￣３，Ｆ（０００）＝１７３６，μ＝７．０９ｃｍ￣（－１），Ｒ＝０．０７０，Ｒ_ｗ＝０．０６３。结构分析结果表明，配阳离子［ＮＨ_４（Ｂ１５Ｃ５）_２］￣＋和配阴离子［Ｃｄ（ＳＣＮ）_３］￣－间靠静电力结合成配合物。     

[{Y(OH)(Benzo-15-Krone-5)(CH3CN)}2]I4, ein Salz mit einem dimeren,hydroxidverbrückten out-of-cavity-Komplex

[{Y(OH)(Benzo-15-Crown-5)(CH₃CN)}₂]I₄, a Salt with a Dimeric Hydroxide-Bridged out-of-cavity Complex Coulorless single crystals of [{Y(OH)(Benzo-15-Crown-5)(CH₃CN)}₂]I₄ are obtained from the reaction of YI₃ and benzo-15-crown-5 in acetonitrile. The crystal structure (monoclinic, P2₁/c, Z = 2, a = 1198.1(1), b = 1375.9(2), c = 1623.5(2) pm, β = 106.50(1)° R1 = 0.0843, wR2 = 0.2193 contains the hydroxide-bridged cationic out-of-cavity dimer.     

冠醚配合物热力学性质的研究(Ⅷ)——若干苯-18-冠-6的甲基衍生物与碱金属配位反应的NMR研究

用NMR谱研究了醚环上具有1-3个甲基的18-冠-6衍生物和一些碱金属离子的配位反应,得到了配合物在溶液中有关构象的信息,籍助于CNDO/2方法计算了在醚碳原子上的电荷密度,并测定了Na⁺配合物的稳定常数。     

Synthesis and Crystal Structure of［Lu（NO_3）_3（H_2O）_2（CH_3CN）］（Benzo－15－C－5）·CH_3CN

ＳｙｎｔｈｅｓｉｓａｎｄＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆ［Ｌｕ（ＮＯ_３）_３（Ｈ_２Ｏ）_２（ＣＨ_３ＣＮ）］（Ｂｅｎｚｏ－１５－Ｃ－５）·ＣＨ_３ＣＮＷａｎｇＲｕｉ－Ｙａｏ；ＪｉｎＺｈｏｎｇ－Ｓｈｅｎｇ；ＮｉＪｉａ－Ｚｕａｎ（Ｌａｂｏｒａｔｏｒｙｏ...     

Synthesis of chromogenic crown ethers and liquid-liquid extraction of alkali metal ions

New crown ethers carrying a pendent phenolic chromophore were synthesized. These crown ethers, on dissociation of the phenolic proton, provide lipophilic anions which can extract alkali metal cations into 1,2-dichloroethane by forming highly-colored uncharged metal complexes. Structural effects on the extraction were studied for possible use of these crown ethers as extraction—spectrophotometric reagents selective for alkali metals. The following factors are discussed in detail: (i) nature of the crown ether ring (ring size. aza-crown or standard crown ether), (ii) nature of the pendent phenolic group, and (iii) geometry between the crown ether center and pendent phenolic group. 15-Crown-5 or smaller ring-sized reagents favored the extraction of lithium ion when the basicity of the pendent phenolate was relatively high and a six-membered “chelate” ring was possible for the phenolate and the crown ether-bound metal. 15-Crown-5 type reagents were sodium-selective when an eight-membered “chelate” ring was possible between the phenolate and the crown ether-bound metal. 18-Crown-6 type reagents were generally potassium-selective. However, these selectivities were not absolute, and other structural parameters, steric and conformational, must be considered to explain in detail the selectivities of the individual reagents.     

Hexafluoroantimony(V) salts of the cationic Ti(IV) fluoride non metallocene complexes [TiF3(MeCN)3]+ and [TiF2L]2+ (L = 15-Crown-5 and 18-Crown-6). Preparation, characterization and thermodynamic stability

The cationic titanium fluoride containing complexes [fac-TiF3(MeCN)3][SbF6].MeCN (1), [trans-TiF2(15-Crown-5)][SbF6]2(2) and [trans-TiF2(18-Crown-6)][SbF6]2(2), were prepared by the reaction of TiF4, the molecular ligand and SbF5 in MeCN. Complexes 1-3 were characterized by X-ray single crystal analysis, elemental analysis, IR, NMR and mass spectroscopy. Titanium tetrafluoride reacts with the SbF5 in SO2 with the formation of fac-[TiF3(SO2)3]+, detected by 19F NMR. Application of the volume-based approach to thermodynamics (VBT) offers a means, for the first time, of exploring the energetics surrounding these materials and in the thermodynamic section a discussion of this new approach is provided. It emerges that the basis of the thermodynamic driving force of formation of [TiF3L3][SbF6](s) salts, that enforces the unfavourable [DeltaH degrees =+ 237 (+/-20) kJ mol(-1)] fluoride ion transfer from the Lewis acid TiF4(s) to SbF5(l) to give the hypothetical [TiF3]+[SbF6]-(s), is the higher Ti-L (L = ligand) bond energy in the cationic complexes [TiF3L3]+ as compared to that in the molecular adducts TiF4L2(s) and SbF5L(s) so giving rise to larger enthalpies of complexation of [TiF3]+(g) by 3L(g) compared to those for complexation of TiF4(g) by 2L(g) and SbF5(g) by 1L(g). Formation of the trans-[TiF2(15-Crown-5)]2+ and trans-[TiF2(18-Crown-6)]2+ is accounted for the stabilization of [TiF2]2+ cation by the five donor acceptor Ti-O contacts and the accompanying positive charge delocalization. Cationic titanium(IV) complexes fac-[TiF3MeCN)3-nLn]+(n= 0-3) and cis-[TiF318-Crown-6)]+, trans-[TiF2(Crown)]2+(Crown = 15-Crown-5 and 18-Crown-6) were obtained in MeCN solution by the reaction of fac-[TiF3(MeCN)3]+ and L = Et2, THF, H2 or crown ethers. Complexes fac-[TiF3(MeCN)3-nLn][SbF6] L = Et2, THF, H2O, crown ethers are unstable in MeCN solution and slowly decompose giving molecular complexes cis-TiF4L2, cis-TiF4(Crown), SbF5L, titanium oxofluoride and alkoxide complexes. The structure of the fac-[TiF3(MeCN)3]+ is similar to the fac-[TiCl3(MeCN)3]+ and the complexes trans-[TiF2L]2+ L = 15-Crown-5, 18-Crown-6 have very similar geometries to that of trans-[TiCl2(15-Crown-5)]+ showing that the essential features of coordination are the same for the cationic titanium chloride and fluoride complexes with MeCN and 15-Crown-5, 18-Crown-6.     

Polarographic determination of In(III) and Cd(II) in the presence of a crown ether

Summary The simultaneous determination of In(III) and Cd(II), whose reduction potentials are very close to each other, was investigated by polarography in the presence of a crown ether such as 12-Crown-4, 15-Crown-5, or 18-Crown-6. An addition of the crown ether shifts the reduction potential of In(III) towards the negative side, its current remaining unchanged, while that of Cd(II) almost did not change, also leaving the wave current constant. Therefore, the difference in reduction potentials between two ions became appreciably large for the simultaneous determination by polarography.     

Volume and compressibility changes of complex formation between 18-Crown-6 and NaCl,KCl, and CsCl in water

The apparent molal volumes and compressibilities of NaCl, KCl, and CsCl in mixtures of 18-Crown-6 and water have been calculated from density and speed-of-sound measurements at 25°C. The partial molal volumes and compressibilities of the salts when all cations have formed complexes with 18-Crown-6 molecules have been evaluated. The sign and magnitude of the volume and compressibility changes of complex formation strongly suggest that the charge of the cation becomes very effectively screened by the crown ether.     

Study of complexation of phenylaza-15-crwon-5, 4-nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag+, Tl+ and Pb2+ ions in methanol by competitive potentiometry

The complexation reaction of phenylaza-15-crwon-5, 4- nitrobenzo- 15-crown-5, and benzo-15-crown-5 with Ag⁺, Tl⁺ and Pb²⁺ ions in methanol solution have been studied by a competitive potentiometric method. The Ag⁺/Ag electrode used both as an indicator and reference electrode in a concentration cell. The emf of cell monitored as the crown ethers concentration varies through the titration. The stoichiometry and stability constants of resulting complexes have been evaluated by MINIQUAD. The stoichiometry for all resulting complexes was 1:1. The stability of these metal ions with derivatives of 15-crown-5 are in order phenylaza-15-crown-5 > Benzo-15-crown-5 > 4-nitrobenzo-15-crown-5, and for the each used crown ethers are as Pb²⁺ > Ag⁺ > Tl⁺. The effect of the substituted group on the stability of resulting complexes was considered. The obtained results are novel and interesting.     

基于密度泛函理论研究锂-冠醚复合物的结构和热力学参数

冠醚对碱金属离子具有高选择性,在锂元素的分离富集上有着广泛的应用。本文基于密度泛函理论（DFT）研究了冠醚环大小、取代基种类、配位原子种类和数量等因素对冠醚空间结构和热力学参数的影响。结果表明,苯并冠醚系列中的苯并-15-冠-5具有更好的配位能力,取代基、配位原子对冠醚的络合能力均有一定影响,因此可通过选择合适的冠醚环,引入供电子基团和含氮杂原子等方法来改善冠醚的分离富集能力。这对冠醚体系分离富集锂元素具有重要的指导意义。     

Ein Netzwerk aus Iodid-Ionen und Iod-Molekülen in der Kristallstruktur von [Pr(Benzo-15-Krone-5)2]I21

A Three Dimensional Network of Iodide Ions and Iodine Molecules in the Crystal Structure of [Pr(Benzo-15-Crown-5)₂]I₂₁ Black polyhedra of [Pr(benzo-15-crown-5)₂]I₂₁ were grown from an ethanol / dichlormethane solution of PrI₃, benzo-15-crown-5 and I₂. The crystal structure (orthorhombic, P2₁cn, a = 1201.1(1), b = 2168.3(1), c = 2571.1(1) pm, Z = 4) is built up from sandwich like cations [Pr(benzo-15-crown-5)₂]³⁺ and polyiodide anions I₂₁^3-. This unique polyiodide anion exhibits a complex connection pattern of iodide ions and iodine molecules with variable bond lengths forming a complicated network.     

色层法检测王冠化合物对稀土元素的络合能力

本文应用反相纸色层法和静态吸附平衡法检测了王冠化合物与稀土离子之间的络合能力和水相阴离子类型对络合能力的影响。所用的王冠化合物有:B-15-C-5,DB-18-C-6,四氢呋喃丙酮四聚体,DB-18-C-6-甲醛缩聚物和B-15-C-5-甲醛缩聚物。得到如下主要结果:1.不同王冠化合物的络合能力顺序是;B-15-C-5>DB-18-C-6》四氢呋喃丙酮吗聚体,另B-15-C-5-甲醛缩聚物>DB-18-C-6-甲醛缩聚物。2.稀土离子络合能力的顺序是:Sm³⁺Er³⁺=La³⁺(反相纸色层法),Er³⁺>Eu³⁺>La³⁺(吸附平衡法)。3.与不同阴离子缔合的离子对的稳定性顺序是:苦味酸根>三氯代乙酸根>磺基水杨酸根》Cl^-、NO₃^-、ClO₄^-及SO₄⁼。     

Detection of lead(II) using an glassy carbon electrode modified with Nafion, carbon nanotubes and benzo-18-crown-6

A glassy carbon electrode was modified with Nafion, carbon nanotubes and benzo-18-crown-6 to give an electrode for the selective determination of lead(II) via square wave anodic stripping voltammetry. The use of carbon nanotubes with their extraordinary electrical conductivity and strong adsorption ability warrants high sensitivity. Benzo-18-crown-6 is employed as a “molecular scavenger” because of its excellent selectivity for lead(II). The modified electrode shows enhanced sensitivity, reproducibility and selectivity for lead(II) even without applying an electrical potential during the accumulation time. It responds linearly to lead(II) in the 1 to 30 nM concentration range (with a correlation coefficient of 0.9992) after a 10-min accumulation time. The detection limit is 1 nM. The sensor exhibits excellent selectivity over other heavy metal ions such as Cd(II), Cu(II), Zn(II), and Hg(II).

Allylation of phenoxides by crown ethers and their polymers

Allylation of sodium phenoxide in the presence of crown ethers produces a high ratio of O/O + C allylation when conducted in water, phenol, benzene, or diethyl ether. The striking increase in the product ratios is attributed to specific complexation of the crown ethers that facilitate the dissociation of the ion pair aggregate of the sodioderivative in benzene or diethyl ether. The crown ethers may act as a phase transfer catalyst when the reaction is run in water. Furthermore, the O/O + C ratios of the allylation strongly depend on the kind of crown ethers used. To examine their effect the allylation of sodium phenoxide was studied with various crown ethers, such as 18-crown-6, benzo-18-crown-6, benzo-15-crown-5, poly(vinylmonobenzo-15-crown-5), and poly(vinylmono-benzo-18-crown-6), as catalysts. It was found that among these crown ethers poly(vinylmono-benzo-15-crown-5) was the most effective catalyst.     

Solvent extraction of silver and thallium picrates with poly- and bis-(crown ether)s

Summary Solvent extraction of silver and thallium picrates by new poly- and bis(crown ether)s, which contain benzo-15-crown-5 or benzo-18-crown-6 moieties, was carried out in water-chloroform system. The poly- and bis(crown ether)s showed higher extractability for both metals than the corresponding monocyclic crown ethers.Especially poly- and bis(benzo-15-crown-5) were found to be quite effective extracting agents for Tl⁺.The extraction equilibrium constants and the complexation constants for the chloroform phase were also estimated.

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Lösungsmittelextraktion von Silber- und Thalliumpikraten mit Poly- und Bis-Kronenethern

Zusammenfassung Die Extraktion der Pikrate wurde in Wasser/Chloroform mit neuen Poly- und Bis-Kronenethern durchgeführt, die Benzo-15-Krone-5- oder Benzo-18-krone-6-Komponenten enthielten. Die Poly- und Bis-Kronenether wiesen für beide Metalle eine bessere Extrahierbarkeit auf als die entsprechenden monocyclischen Kronenether. Insbesondere Poly- und Bis(benzo-15-krone-5) erwiesen sich als wirkungsvolle Extraktionsmittel für Thallium(I). Die Extraktions-Gleichgewichtskonstanten und die Komplexbildungskonstanten für die Chloroformphase wurden bestimmt.

     

几种有机溶剂中15冠5及苯并15冠5与Mg~(2+)配合的NMR研究

本文用一维及二维NMR方法研究了溶剂对15冠5(15C5)和苯并15冠5(B15C5)与Mg~(2+)配合的影响。结果表明,在丙酮,乙腈,硝基甲烷,四氢呋喃以及氯仿中,冠醚与Mg~(2+)形成稳定的1:1配合物,且配合态与自由态冠醚间的化学交换在NMR标尺上为慢交换过程;而在二甲亚砜,二甲基甲酰胺,二甲基乙酰胺和吡啶中,由于溶剂对Mg~(2+)的竞争作用而使冠醚未能与Mg~(2+)有效配合。     

Über die Kronenetherkomplexe [K(15-Krone-5)2]3[Sb3I12], [TeCl3(15-Krone-5)][TeCl5] und [TeCl3(15-Krone-5)]2[TeCl6]

On the Crown Ether Complexes [K(15-Crown-5)₂]₃[Sb₃I₁₂], [TeCl₃(15-Crown-5)][TeCl₅], and [TeCl₃(15-Crown-5)]₂[TeCl₆] Orange-coloured crystals of [K(15-crown-5)₂]₃[Sb₃I₁₂] are formed in the reaction of potassium iodide with antimony triiodide and 15-crown-5 in acetonitrile solution. An X-ray structure determination reveals severe disorder of the crown ether molecules, which coordinate to the potassium atoms in a sandwich array; so only the [Sb₃I₁₂]^3? ion and the potassium positions were ascertained. The anion is a centrosymmetric trimer (symmetry C_2h), which can be understood as central SbI₆^3? ion, coordinated by two SbI₃ molecules. (Space group C2/m), Z = 2, 3263 observed, independent reflections, R = 0.06, lattice dimensions at 20°C: a = 2541.1 pm, b = 1441.7 pm, c = 1588.4 pm, β = 113.33°. The tellurium complexes [TeCl₃(15-crown-5)] [TeCl₅] and [TeCl₃(15-crown-5)]₂[TeCl₆] are prepared by reaction of TeCl₄ with 15-crown-5 in acetonitrile solution, forming yellow-green crystals sensitive to moisture. They are characterized by their i.r. spectra.     

Solvent extraction of alkaline earth metal picrates with poly- and bis(crown ether)s

Summary Solvent extraction of alkaline earth metal picrates with poly- and bis(crown ether)s containing benzo-15-crown-5- and benzo-18-crown-6 moieties was carried out in a water-chloroform system. The poly- and bis(crown ether)s showed larger extractability for the metal picrates than the corresponding monocyclic crown ethers. Especially, poly- and bis(benzo-15-crown-5), and bis(benzo-18-crown-6) were found to have relatively high extractability and selectivity for Ba²⁺ and Sr²⁺, respectively.

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Lösungsmittelextraktion von Erdalkalipikraten mit Hilfe von Poly- und Bis-Kronenethern

Zusammenfassung Poly- und Bis-Kronenether mit Benzo-15-krone-5- und Benzo-18-krone-6-Einheiten wurden zur Extraktion von Erdalkalipikraten im Wasser-Chloroform-System verwendet. Die genannten Ether zeigten eine bessere Extraktionsfähigkeit für die Pikrate als die entsprechenden monocyclischen Kronenether. Im Falle von Ba²⁺ und Sr²⁺ ergab sich eine besonders gute Extrahierbarkeit und Selektivität mit Poly- und Bis(benzo-15-krone-5)- und Bis(benzo-18-krone-6)-Ethern.