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1.
An ab initio, quantum mechanical study of the Wurster's crown analogue of 18-crown-6 and its interactions with the alkali metal cations are presented. This study explores methods for accurately treating large, electron-rich species while providing an understanding of the molecular behavior of a representative member of this class of crowns. The molecular geometries, binding energies, and binding enthalpies are evaluated with methods similar to those reported for the analysis of 18-crown-6 and its alkali metal complexes to facilitate direct comparison. Hybrid density functional methods are applied to gauge the effects of electron correlation on the geometries of the electron-rich phenylenediamine moiety present in the Wurster's crowns. While the structure of the crown ether backbone is largely unperturbed by the incorporation of the redox active functionality, the alkali metal binding enthalpies are uniformly stronger for the Wurster's crown complexes, adding 1.8 to 5.1 kcal/mol to the strength of the interaction, depending on cation type. The additional strength, due to the exchange of an oxygen donor atom in the crown ether backbone by a nitrogen donor supplied by the redox group, is tightly coupled to the rotation of the dimethylaminophenyl group with respect to the plane of the macrocycle. Gas-phase selectivities favor the more highly charge-dense cations, while the explicit addition of only a few waters of hydration in the calculations recovers the selectivities expected in solution. The alkali metal binding affinity to the singly oxidized Wurster's crown is significantly diminished, while it is completely eliminated for the doubly oxidized ligand. 相似文献
2.
Two isomeric redox-responsive azathiacrown ethers, based on p-phenylenediamine, have been synthesized in traditional crown (L1) and crownophane (L2) architectures. Each of these "Wurster's crowns" was designed to target the encapsulation of transition or heavy metal ions. The solid-state structures of these ligands show binding cavities defined by three exocyclic sulfur atoms and either a N donor atom (L1) or the electron-rich pi face of the phenylenediamine subunit (L2). The ability of these ligands to form complexes with platinum(II) was investigated by various techniques including 1H NMR spectroscopy, electrospray mass spectrometry, cyclic voltammetry, and single-crystal X-ray analysis. The traditional crown geometry proved to be better at forming stable endocyclic complexes with Pt(II) than the crownophane geometry. The square-planar Pt(II) crown complex includes direct bonding to the redox center (Pt1-N1 = 2.125 angstroms and Pt1-S(av) = 2.278 angstroms) with concomitant polarization of the phenylenediamine moiety. This results in the crown complex oxidizing 916 mV more anodically than the free ligand. In contrast, modest shifts in the oxidation potential of the crownophane isomer indicate poor interaction between the redox center and complexed Pt(II) ion. 相似文献
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Isomeric p- and o-phenylenediamine-containing macrocyclic hosts (Wurster's thiacrown ethers L1 and L2, respectively) were prepared and studied as Hg(II) ionophores. The distinct electrochemical properties of the two hosts allowed for the formation of a coordination compound with the ortho-Wurster's thiacrown ether but not the para isomer. In the latter case, the Hg(II) ion served as an oxidant in an electron-transfer reaction with the host. Solutions of the Hg(II) complex of L2 were studied by 13C NMR spectroscopy and cyclic voltammetry and revealed a strong interaction between the redox-active phenylenediamine subunit and the bound metal cation. An X-ray analysis confirmed the participation of the three macrocyclic S atoms and both phenylenediamine N atoms in the stabilization of the complex. 相似文献
5.
E. Yu. Kulygina V. I. Vetrogon S. S. Basok N. G. Luk’yanenko 《Russian Journal of General Chemistry》2005,75(4):628-631
The stability constants of complexes of 12-, 15-, and 18-membered diaza crown ethers, N,N′-dimethyl diaza crown ethers, and N,N′-bis(2-hydroxyethyl) diaza crown ethers with alkali and alkaline-earth metal ions in 95% aqueous methanol at 25°C were determined. The stability of the complexes of unsubstituted diaza crown ethers with alkali metal cations is low, probably because of stabilization of the exo,exo conformation of the ligands due to interaction of the nitrogen lone electron pairs with the solvent. The complexes with the double-charged cations are appreciably more stable. N,N′-Dimethyl diaza crown ethers form stable complexes with all the ions studied. As compared to the dimethyl derivatives, N,N′-bis(2-hydroxyethyl) diaza crown ethers form more stable complexes with the Na+, K+, Ca2+, Sr2+, and Ba2+ ions, which is due to participation of the side hydroxyethyl groups in the coordination.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 665–669.Original Russian Text Copyright © 2005 by Kulygina, Vetrogon, Basok, Luk’yanenko. 相似文献
6.
用两类结构不同的Schiff碱型、仲胺型双-(苯并-18-冠-6)在氯仿-水体系中对碱金属苦味酸盐进行萃取,测量了配合物组成比和萃取平衡常数。 相似文献
7.
仲胺型双冠醚与四苯硼酸碱金属盐在丙酮溶液中。25℃下的电导说明它们与Na~+可能形成1∶1络合物(冠醚单元∶金属离子),而与K~+、Rb~+、Cs~+离子则形成2∶1络合物。用Schlff碱型和仲胺型双-(苯并15-冠-5)在水-氯仿体系中进行萃取,测量了分配比D和萃取平衡常数K,发现后者的K值均大于前者。双冠醚F_2对K~+的萃取能力最强,选择性最佳。 相似文献
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The binding properties of two thiacalix[4]arene-bis-crown[n] derivatives (n = 5 and 6) were examined through extraction experiments. The stability constants of the resulting complexes in methanol were determined. The replacement of the bridging CH2 groups by sulfur atoms leads to a strong decrease in both extraction and complexation levels of alkali metal ions but does not affect the selectivity within the series of crown ethers. The stability of complexes with heavy metal ions does not change markedly on passing from thiacalix[4]arene-bis-crown[n] ethers to their calix[4]arene-bis-crown[n] counterparts; therefore no clear-cut conclusions about the possible interactions between these cations and the sulfur atoms can be drawn. 相似文献
10.
Sheryl M. Blair Esther C. Kempen Jennifer S. Brodbelt 《Journal of the American Society for Mass Spectrometry》1998,9(10):1049-1059
The quantifiable relationship between the equilibrium solution composition and electrospray (ESI) mass spectral peak intensities of simple host-guest complexes was investigated. Specifically, host-guest complexes of simple crown ethers or glymes with alkali metals and ammonium ions were studied. Comparisons were made between the theoretical concentrations of host-guest complexes derived in solution from known stability constants and the peak intensities for the complexes observed by ESI mass spectrometry (ESI-MS). Two types of complexation experiments were undertaken. First, complexation of a single guest ion, such as an alkali metal, and two crown ethers was studied to evaluate the determination of binding selectivities. Second, complexation of two different guest ions by a single polyether host was also examined. In general, solvation was found to play an integral part in the ability to quantify binding selectivities by ESI-MS. The more similar the solvation energies of the two complexes in the mixture, the more quantifiable their binding selectivities by ESI-MS. In some cases, excellent correlation was obtained between the theoretically predicted selectivity ratios and the ESI mass spectral ratios, in particular when the ESI ratios were adjusted based on evaluation of ESI response factors for the various host-guest complexes. 相似文献
11.
Blair SM Brodbelt JS Marchand AP Chong HS Alihodzic S 《Journal of the American Society for Mass Spectrometry》2000,11(10):884-891
Microelectrospray ionization mass spectrometry (MESI-MS) is used to evaluate alkali metal binding selectivities of a variety of macrocyclic compounds. Well-studied crown ethers are used to validate the MESI-MS method. A quantitative correlation between MESI mass spectral ion intensities and solution equilibrium distributions of complexes is obtained for the mixtures containing a single host and different alkali metal guest ions. The MESI-MS method is successfully applied for the determination of the alkali metal binding selectivities of a series of cage-functionalized aza-crown ethers and relevant model compounds in methanol and chloroform solutions. The binding selectivities parallel previous results obtained using conventional spectrophotometric extraction methods. Structural differences in the host compounds, such as the presence of a cage functionality, binding cavity size, and overall flexibility, cause significant changes in the binding selectivities. 相似文献
12.
Yoichi Habata Sadatoshi Akabori Xian Xin Zhang Reed M. Izatt Jerald S. Bradshaw 《Journal of heterocyclic chemistry》2001,38(6):1329-1340
A series of monoaza‐15‐crown‐5 ethers (2b‐2h) having 4′‐hydroxy‐3′,5′‐disubstituted benzyl groups have been prepared by the Mannich reaction of 2,6‐disubstituted phenols with the corresponding N‐methoxymethylmonoaza‐crown ethers. Competitive transport through a chloroform membrane by 12‐crown‐4 derivatives (lithium, potassium and cesium) and 15‐crown‐5 derivatives (sodium, potassium and cesium) were measured under basic‐source phase and acidic‐receiving phase conditions. All ligands transported size‐matched alkali‐metal cations. Ligands 1h and 2h with two fluorine atoms in the side arm gave higher metal ion transport rates than those of dimethyl‐ (1a and 2a), diisopropyl‐ (1b and 2b), and butylmethyl‐ (1d and 2d) derivatives. X‐ray crystal structures of six alkali metal complexes with monoaza‐12‐crown‐4‐derivatives ( 1b‐LiSCN, 1b‐KSCN, 1c‐NaSCN, 1d‐LiSCN, 1f‐RbSCN and 1h‐LiSCN ) and three alkali metal complexes with 15‐crown‐5 derivatives ( 2b‐KSCN, 2c‐KSCN , and 2e‐KSCN ) along with crystal structures of some new ligands (1b, 1c, 1d, 1f, and 2c) are also reported. These X‐ray analyses indicate that the crystal structures of the alkali metal ion complexes of these new armed‐crown ethers changed depending on the substituents at the 3′‐ and 5′‐positions of the appended hydroxybenzyl arms. 相似文献
13.
Bis-crown ethers in which the benzo-15-crown-5 units were linked to 1,1′-positions of metallocene (M = Fe or Ru) with amide, ester, or ? C? C? bonds were synthesized. Complexing ability of the compounds with alkali, alkali earth, and transition metal cations were measured by the solvent extraction method. The results showed that these crown ethers had high affinity toward alkali metal cations (Li+, Na+, K+, and Rb+) and heavy-metal cations (Ag+ and Tl+). The difference of complexing ability for metal cations between ferrocene and ruthenocene derivatives could not be detected significantly. The extractability of metallocene-bis-crown ethers for metal cations was more larger than that of the corresponding mono-crown ethers, and irregular increments of extractability were explained by assuming the existence of a mixture of 1:1 and 2:1 complexes. 相似文献
14.
The reaction of N,N-di(oligooxyethylene)amines with arenesulfonyl chloride in the presence of alkali metal hydroxide was investigate. It was found that the monoarenesulfonates of N,N-di(oligooxyethylene)amines were first formed as intermediates, and their subsequent intramolecular cyclization gave N-unsubstituted monoaza crown ethers rather selectively. 相似文献
15.
Reed M. Izatt Gypzy C. Lindh Jan F. Biernat Maria Bochenska Ronald L. Bruening Jerald S. Bradshaw James J. Christensen 《Journal of inclusion phenomena and macrocyclic chemistry》1989,7(5):487-499
The transport of alkali metal cations by several macrocycles possessing two sulfonamide groups as a part of an 18-, 20-, or 21-membered macroring has been studied. Some of these compounds were found to be more effective transport agents than the proton-ionizable pyridone- and triazole-containing crown ethers reported previously. The factors affecting transport, such as ring size, source and receiving phase pH, and the nature of the groups attached to the sulfonamide nitrogen atoms were examined. Also, extraction experiments by some of the ligands were performed. The behavior of sulfonamide type crowns in single and competitive transport of the alkali metal cations is explained. The mechanism of transport appears to be complex. Transport of one or two cations per molecule of the disulfonamide carriers occurs. Complexation of these cations appears to occur both within and outside the macrocycle cavity. Our results also suggest that kinetic factors may play a significant role in transport rates and selectivities.Deceased: September 5, 1987. 相似文献
16.
A new type of macrocyclic polyethers has been synthesized. It consists of an azacrown ether as mother ring, e.g. 1,7-dioxa-4,10-diaza-cyclododecane (1a) or 1,7,10,16-tetraoxa-4,13-diazacycloocatadecane (1b), and two side chains attached on the two nitrogen atoms of 1a or 1b. A number of these new crown ethers are obtained by alkylation of the two secondary amino groups of 1a or 1b with corresponding halides, BrCH2(CH2OCH2)nCH2OR, in the presence of potassium carbonate. The crown-alkali metal complex thus obtained is hydrolyzed by acid. In order to obtain pure crown ether the reaction mixture is treated with tetramethylammonium hydroxide and followed by solvent extraction. The ability of complexing alkali cations of macrocyclic polyethers in terms of the equilibrium constant have been studied by the method of solubilities of salts in chloroform. It is shown that the size of the mother ring, the number of oxygen atoms either in the ring or in the side-chains, and the ionic radius of the alkali metal are the factors governing the stability of the metal complexes. Most of these new crown ethers possess high ability for alkali metal complexation some of them, such as N,N′- di-β-methoxyethyl-1,7-dioxa-4,10-diaza-cyclododecanc (13a), possesses higher selectivity for Na+ and K+ ions than 18-crown-6- and 4,4′(5′)-dimethylbenz-30-crown-10. 相似文献
17.
Tao Song Lei Liu Jingwei Zhao Huiling Jiang Shizheng Zhu Liangzhong Xu 《Tetrahedron》2012,68(27-28):5677-5682
At room temperature, 4-ethoxy-1,1,1-trifluorobut-3-en-2-one reacted with alkali metal salts of diethyl malonate to give two kinds of complexes. One is the solvent molecule-involved complexes, and the other is a sheer ion aggregates composed by alkali metal cation and carbanion. Both crystals are fully characterized by spectroscopic methods and single crystal X-ray diffraction analyses. 相似文献
18.
A computerized conductometric procedure for the determination of stability constants of the complexes of crown ethers (15-crown-5, benzo-15-crown-5 and 12-crown-4) with alkali metal salts in polar solvents is described, based on a microcomputer-controlled titration system. For the control of the experiments from software, a modular computer program was written in FORTH computer language. The procedure is especially suitable for the study of 1:2 metal ion/ligand complexes, which occur frequently with the compounds used. For the study of the interaction between crown ethers and neutral molecules, an indirect procedure is outlined. 相似文献
19.
Chien-Chung Liou Jennifer S. Brodbelt 《Journal of the American Society for Mass Spectrometry》1992,3(5):543-548
Ladders of relative alkali ion affinities of crown ethers and acyclic analogs were constructed by using the kinetic method. The adducts consisting of two different ethers bound by an alkali metal ion, (M1 + Cat + M2)+, were formed by using fast atom bombardment ionization to desorb the crown ethers and alkali metal ions, then collisionally activated to induce dissociation to (M1 + Cat)+ and (M2 + Cat)+ ions. Based on the relative abundances of the cationized ethers formed, orders of relative alkali ion affinities were assigned. The crown ethers showed higher affinities for specific sizes of metal ions, and this was attributed in part to the optimal spatial fit concept. Size selectivities were more pronounced for the smaller alkali metal ions such as Li+, Na+, and K+ than the larger ions such as Cs+ and Rb+. In general, the cyclic ethers exhibited greater alkali metal ion affinities than the corresponding acyclic analogs, although these effects were less dramatic as the size of the alkali metal ion increased. 相似文献
20.
H. D. Inerowicz J. Chojnacki A. Merz T. Futterer 《Journal of inclusion phenomena and macrocyclic chemistry》2000,38(1-4):123-132
The complexation reactions between the macrocyclic polyethers dibenzo-18-crown-6, benzo-18-crown-6, benzo-15-crown-5 and polyethers bearing a stilbene unit with alkali metal and silver cations have been studied conductometrically in nitromethane. The formation constants of 1 : 1 and 1 : 2 (metal : ligand) complexes were determined and found to decrease with increasing cation diameter. The stability of the stilbene crown – metal cation complexes is lower than for complexes of other investigated crown ethers with analogous cations. There seem to be some effects of double bond-silver ion interactions. 相似文献