共查询到20条相似文献,搜索用时 15 毫秒
1.
Ben Sdira S Felix CP Giudicelli MB Seigle-Ferrand PF Perrin M Lamartine RJ 《The Journal of organic chemistry》2003,68(17):6632-6638
Chiral p-tert-butylcalix[4]arenes functionalized at the lower rim with amino acid residues have been prepared. The (1)H and (13)C NMR spectra indicate that the macrocycles preferably adopt a cone conformation. Calix[4]arenes bearing amino acid moieties were prepared as a class of receptors selective for anions that are bound through hydrogen bonding with the NH group. The association constants are dependent on the nature of the substituents at the lower rim. Derivative 9 shows the strongest complexation and the largest selectivity for N-tosyl-(L)-alaninate. Finally, a preliminary X-ray crystal study of the difunctionalized receptor 6f shows the "flattened cone" conformation in the solid state. 相似文献
2.
Giannetto M Mori G Notti A Pappalardo S Parisi MF 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(15):3354-3362
The stepwise synthesis of cone and partial cone 1,3-bridged n-propoxy-calix[4]crown ethers ("monomers" 2 and 3) with an electropolymerizable 2,2'-dithiophene-3-yl-hexylene functionality at the lower rim, is described. The potential of 2 and 3 as sensing agents for alkali metal ions was investigated by 1H NMR titration experiments with NaSCN and KSCN. The results obtained have confirmed that the presence of the heterocyclic subunit does not affect the well-known size-selectivity observed with calix[4]crowns. Monomers 2 and 3 were electropolymerized (Pt as a working electrode, CH2Cl2/CH3CN, Bu4NPF6) to produce the title chemically modified electrodes (CMEs). After coating with a PVC membrane containing a lipophylic cation exchanger, CMEs based on calix[4]-crown-5 2b (cone) and 3b (partial cone) were tested for the potentiometric recognition of alkali metal ions in aqueous solution. In agreement with NMR titration studies, a satisfactory potentiometric response in terms of K+/Na+ selectivity was obtained only with CME 2b (pK(K/Na) 1.51). The amperometric responses of PVC-uncoated CMEs were studied by cyclic voltammetry (CV) experiments in CH3CN solution. High Na- selectivity was found with the CME based on partial cone calix[4]crown-4 3a, and frequency response analysis (FRA) measurements support this finding. 相似文献
3.
Frkanec L Visnjevac A Kojic-Prodic B Zinic M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(3):442-453
Chiral calix[4]arene derivatives with four O-(N-acetyl-PhgOMe), (1), (Phg denotes R-phenylglycine), or O-(N-acetyl-LeuOMe) (2) strands have been synthesised. Both compounds exist in chloroform in stable cone conformations with a noncovalently organised cavity at the lower rim that is formed by circular interstrand amidic hydrogen bonds. Such organisation affects both the selectivity and extraction/transport properties of 1 and 2 toward metal cations. Calix[4]arene derivatives with one OCH2COPhgOMe strand (3), two OCH2COPhgOMe strands (5) and with 1,3-OMe-2,4-(O-CH2COPhgOMe) substituents (4) at the lower rim have also been prepared. For 3, a conformation stabilised by a circular hydrogen-bond arrangement is found in chloroform, while 4 exists as a time-averaged C2 conformation with two intramolecular NH ...OCH3 hydrogen bonds. Compound 5 has a unique hydrogen-bonding motif in solution and in the solid state with two three-centred NH-.. O and two OH...O hydrogen bonds at the lower rim. This motif keeps 5 in the flattened cone conformation in chloroform. The X-ray structure analysis of 1 revealed a molecular structure with C2 symmetry; this structure is organised in infinite chains by intra- and intermolecular H bonds. The solid-state and solution structures of the [1-Na]ClO4 complex are identical, C4 symmetric cone conformations. 相似文献
4.
A chiral nitrogen-containing calix[4]crown 2 bearing optically pure 1,2-diphenyl-1,2-oxyamino residue at lower rim showed excellent chiral recognition between enantiomers of mandelic acid. Using competitive 1H NMR titration the ratio of association constants of (S)- and (R)-mandelic acid with the chiral calix[4]crown was determined to be 102, that is 98% de, which is the best result obtained from artificial receptors for the chiral recognition of mandelic acid up to now. 相似文献
5.
Mayya Korochkina Alessandro Casnati Arturo Arduini Rocco Ungaro Vladimir Kataev Vladimir Alfonsov 《Tetrahedron》2005,61(23):5457-5463
Novel calix[4]arene derivatives functionalized with two or four isosteviol units at the upper rim and a new calix[6]arene having six isosteviol moieties at the lower rim have been synthesized. The structures of these compounds have been confirmed by NMR and mass spectrometry data. All 1H and 13C NMR chemical shifts of isosteviol were fully assigned by extensive NMR spectroscopic methods, and used to clarify the structures and conformations of isosteviol-calixarene conjugates. 相似文献
6.
Luo J Zheng QY Chen CF Huang ZT 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(20):5917-5928
A series of inherently chiral calix[4]arenes with cone and partial cone conformations and with crown ether moieties of variable size have been readily synthesized. By taking advantage of the carboxy appendage on the lower rim, these were condensed with the chiral auxiliary (S)-BINOL to form diastereomers which, in most cases, could be separated by preparative TLC, or more desirably, by column chromatography on silica gel (diastereomeric excess >99 % based on HPLC analysis). Seven enantiopure antipodes of inherently chiral calix[4]crowns were obtained after hydrolysis. It has been found that both the size of the crown moiety and alkylation of the last phenolic hydroxy group (accompanied with or without a change in the conformation) affect the separation of the diastereomers. 相似文献
7.
Two armed chiral calix[4]arenes 8-16 functionalized at the lower rim with chiral aminonaphthol units have been prepared and the structures of these receptors characterized by FTIR, (1)H, and (13)C, DEPT and COSY NMR spectroscopy and elemental analysis. The enantioselective recognition of these receptors with various carboxylic acids has been studied by (1)H NMR and UV/Vis spectroscopy. The receptors exhibited different chiral recognition abilities towards the enantiomers of racemic materials and formed 2 : 1 or 1 : 1 complexes between host and guest. It was also demonstrated that chiral calix[4]arenes 9 and 16 could be used as chiral NMR solvating agents to determine the enantiomeric purity of mandelic acid. 相似文献
8.
The first C(3v)-symmetrical calix[6](aza)crown 8 has been obtained in five steps from X(6)H(3)Me(3) 3. The key-step introduction of the triple bridge at the small rim has been achieved through reaction of a tris-arylsulfonamide derivative of tren 1 and tris-tosylcalix[6]arene 6. A (1)H NMR study has shown that the tripodal cap rigidifies the whole edifice, preventing ring inversion and constraining the calixarene core in a straight cone conformation. 相似文献
9.
AbstractSyntheses of p-H-calix[4]arene-1,3-crown-5 and p-tert-butylcalix[4]arene-1,3-crown-5 ligands with two elongated, proton-ionisable side arms in the cone conformation are described. For solvent extractions from aqueous solution into chloroform, the influence of lengthening the lower rim proton-ionisable side arms and addition of para substituents to the upper rim of the calix[4]crown scaffold on the efficiency and selectivity of metal cation solvent extraction are evaluated. 相似文献
10.
Har Mohindra Chawla Rahul Shrivastava 《Journal of inclusion phenomena and macrocyclic chemistry》2009,64(3-4):255-263
A series of novel cone-configurated p-tert-butyl-trimethoxycalix[6]arenes bearing three 2,2′-bipyridyl units at their lower rim have been synthesized. The 1H NMR and 13C NMR spectra of synthesized derivatives revealed that the ring inversion in calix[6]arene could be suppressed by the introduction of three 2,2′-bipyridyl moieties at the lower rim of calix[6]arene scaffold which fixes it into its cone configuration. The complexation ability of the synthesized receptors (5a–d) towards Fe(II) ion was investigated by UV-Visible titration to reveal that the synthesized receptors interact with Fe(II) in a 1:1 binding stoichiometry and respond to a specific oxidation state of the metal ion. The observations have significance for studies directed at the design of molecular receptors for ionic speciation through molecular recognition. 相似文献
11.
Functionalized thiacalix- and calix[4]arene-based Ag ionophores: synthesis and comparative NMR study
Thiacalix[4]arene ionophores comprised of cyclic or linear O,S,N ligating and/or π-coordinate groups on the lower rim were synthesized and their Ag+ binding was studied by 1H NMR methods in comparison with the respective known and novel calix[4]arene counterparts. Calix[4](O,S,N)crowns were found stronger binders than the π-coordinate molecules and thiacalixarene ionophores were generally superior to calixarenes. This study helped to develop silver ion-selective electrodes working in the subnanomolar region. 相似文献
12.
Lee JK Kim SK Bartsch RA Vicens J Miyano S Kim JS 《The Journal of organic chemistry》2003,68(17):6720-6725
Several new thiacalix[4]monocrown and thiacalix[4]biscrown compounds were synthesized. Their metal ion extractabilities are found to be lower than those of conventional calix[4]crowns. By use of X-ray crystal structures and (1)H NMR spectroscopy, this result is explained by weaker electrostatic interactions of the polyether ring oxygen atoms with the metal ions and diminished pi-metal ion interactions between the metal ions and the aromatic rings of the thiacalix[4]crowns. Temperature-dependent (1)H NMR spectroscopic measurements reveal coalescence temperatures T(c)(intra) and T(c)(inter) for metal ion exchange. In one case, this exchange was rationalized as metal ion shuttling through a thiacalix[4]biscrown tube. Since the metal ions are less tightly complexed by the polyether units in thiacalix[4]biscrowns than in conventional calix[4]biscrowns, more facile metal ion exchange between the two polyether units takes place in the former. 相似文献
13.
Khomich E Kashapov M Vatsouro I Shokova E Kovalev V 《Organic & biomolecular chemistry》2006,4(8):1555-1560
Herein we report on the synthesis and ionophore properties of the first asymmetric p-tert-butylcalix[4]-p-R-thiacalix[4]tubes 7a-c (R = t-Bu, H, 1-adamantyl). The target compounds were obtained by the condensation of tosyloxyethoxy-p-tert-butylcalix[4]arene with the corresponding p-R-thiacalix[4]arenes in the presence of K2CO3 in acetonitrile. The complexation with sodium, potassium and rubidium iodides was studied in CDCl3-CD3OD (4:1) medium by means of 1H NMR measurements. It was found that the ionophore properties of calixtubes 7a-c are controlled by the character of the substituents at the upper rim of the thiacalix[4]arene fragment and it was shown that only the molecular tube 7c with an adamantane-containing thiacalixarene unit is capable of quantitatively binding potassium (swiftly) and rubidium (slowly) cations. 相似文献
14.
《Electroanalysis》2004,16(6):472-477
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. 相似文献
15.
Syakaev VV Kazakova EKh Morozova JE Shalaeva YV Latypov SK Konovalov AI 《Journal of colloid and interface science》2012,370(1):19-26
Supramolecular nanoaggregates formed through the association of amphiphilic sulfonatomethylated calix[4]resorcinarenes with different substituents on the lower rim (methyl, pentyl, heptyl) and number of aromatic, aliphatic, and cationic guests differing in their shapes and sizes were investigated in aqueous solution by various NMR techniques ((1)H, 2D NOESY, FT-PGSE). It was shown that slight variations of the alkyl chain length on the lower rim of calixresorcinarenes dramatically change their aggregation behavior. Unlike the other calixresorcinarenes studied, the "head-to-tail" packing mode is observed for calixresorcinarene with pentyl moieties on the lower rim, which is unusual for amphiphilic calixarene aggregates. This calixresorcinarene demonstrates the stronger binding capacity toward the guest molecules due to their encapsulation into the capsule-like aggregate subunits. The guest-host complexation modifies the properties of both components, with the size of the resulted colloid particles being controlled by the guest nature. 相似文献
16.
Victor V. Syakaev Asiya R. Mustafina Julia G. Elistratova Shamil K. Latypov Alexander I. Konovalov 《Supramolecular chemistry》2013,25(5):453-460
Two amphiphilic water-soluble sulfonatomethylated calix[4]resorcinarene derivatives were studied by various 1H NMR techniques (1H NMR titration, 2D NOESY, NMR diffusion measurements). The derivative with methyl moieties at the lower rim (1) was found to be non-aggregated in the range 0–10 mM in aqueous solutions. Lengthening of the lower rim substituent to pentyl (2) results in self-aggregation of 2 in aqueous solutions with the aggregation number varying from 3 at 1 mM to 20 at 10 mM. The 2D NOESY 1H NMR spectroscopy data reveal an unusual head-to-tail packing mode in aqueous solutions, resulting from the cooperative effect of weak hydrophobic interactions. Binding of guests (tetramethylammonium and N-methylpyridinium) results in additional stabilization of the aggregates whilst the head-to-tail packing mode of the aggregate is retained. 相似文献
17.
János B. Czirok Ákos Tarcsay Pál D. Mezei András Simon László Balázs 《Supramolecular chemistry》2013,25(10-12):722-728
The size limit of substituents allowing O-through-the-annulus rotation of substituted calix[4]arenes was further extended to the propargyloxy group in 24-propargyloxy-25,26,27-tris(N,N-dimethylcarbamoylmethoxy)-p-tert-butylcalix[4]arene by demonstrating its free but slow motion affording equilibrium between the partial cone and 1,2-alternate conformers. The effect of solvent and upper rim substituents R1 on the conformational inversion was investigated by means of 1H NMR. The rotational isomerisation of the parent (R1 = H) analogue could not unambiguously be detected. The experimental results were supported by comprehensive density functional theory studies. 相似文献
18.
杯[4]芳烃的上端和下端通过金属复分解闭环反应以较高产率合成一系列新型杯[4]冠醚衍生物(8a-c),目标产物结构经元素分析、IR、MS、1H NMR及13C NMR证实。 相似文献
19.
[reaction: see text] Several calix[4]arene derivatives propylated on the lower rim and substituted on the upper rim with amino or carboxyl groups have been synthesized. Examples include calixarenes substituted with alanino (C- and N-linked), amino, carboxy, carboxyphenyl, and amidino groups. The self-assembly of these derivatized calixarenes into heterodimers has been studied by NMR in DMSO-d(6) or CD(3)OD with 5% aqueous phosphate buffer. 相似文献
20.
An efficient method has been developed for the synthesis of 2-[3(5)-aryl(methyl)pyrazol-4-yl]-1H-benzimidazoles by cyclocondensation
of 2-acylmethyl-1H-benzimidazoles benzoylhydrazones with DMF dimethylacetal. The tautomerism of the compounds obtained via
migrations of a proton between the pyrazole nitrogen atoms has been studied by 1H NMR. The more stable tautomers have electron acceptor aryl substituents placed at position 3 of the pyrazole ring and electron
donor aryl substituents or a methyl at position 5.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1370–1377, September, 2006. 相似文献