共查询到20条相似文献,搜索用时 31 毫秒
1.
Jianyu Sun 《Tetrahedron》2009,65(35):7296-9353
A new [4]carceplex (2·guest) is reported. It is composed of two cavitands linked by four disulfide bonds. It forms twistomers, which interconvert on a millisecond timescale. The energy barrier for interconversion of twistomers is guest-dependent. Formation of [4]carceplex 2·guest is template dependent. The selectivity in templates is flat relative to most previous related template work. Larger kin [5]carceplex 1·guests were reinvestigated. A crystal structure confirms the twist between the hemispherical cavitands. Use of a redox buffer allowed dynamic combinatorial chemistry to be performed between pairs of templates. 相似文献
2.
Iman Elidrisi Pralav V. Bhatt Thavendran Govender Hendrik G. Kruger Glenn E.M. Maguire 《Tetrahedron》2014
The synthesis of seven novel protected amino acid cavitands is reported. All have four pendant n-undecyl chains and ‘headgroups’ connected by a two-carbon spacer at four positions on the aromatic rings. The amino acids employed are glycine, alanine, phenylalanine, leucine, proline, tryptophan, serine, glutamine and lysine. The structures of the compounds were elucidated using one- and two-dimensional NMR techniques, which verified that all tetra-substituted cavitands have symmetrical C4v conformation. This is the first example of a complete study for amino acid cavitand derivatives. 相似文献
3.
O. I. Kalchenko E. Da Silva A. W. Coleman 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(3-4):305-310
Reversed-phase high performance liquid chromatography (Separon SGX CN, UV detection at 254~nm and water as mobile phase) was applied to thestudy of the host–guest complexation ofp-H-37-(2-carboxy-methyloxy)-calix-[6]-arene (1) and p-sulphonato-37-(2-carboxy-methyloxy)-calix-[6]-arene (2)with 15 amino acids in the mobile phase. It was established that the formation ofthe inclusion complexes results in changes in the retention times and capacity factorsof amino acids. Stability constants of the complexes were determined. The variations instability constant values may be explained in terms of the different interactions, whichmay occur between amino acids and 1 and 2. 相似文献
4.
Olga Kalchenko Andriy Drapailo Svetlana Shishkina Oleg Shishkin Sergiy Kharchenko Valery Gorbatchuk 《Supramolecular chemistry》2013,25(5):263-268
In this paper, host–guest complexation process of thiacalix[4]arene tetrakis–methylphosphonic and tetrakis–sulphonic acids with amino acids by HPLC and molecular modelling methods has been studied. It was shown that thiacalix[4]arene tetrakis–methylphosphonic acid due to transformability of macrocyclic skeleton and flexibility of methylphosphonic substituents can adopt its conformation for strong multicentre binding of the amino acids with association constant values 530–10,140 M? 1 in water. 相似文献
5.
PhilipJ. Skinner AndrewG. Cheetham Andrew Beeby Volker Gramlich Franois Diederich 《Helvetica chimica acta》2001,84(7):2146-2153
The synthesis of the quinoxaline‐bridged resorcin[4]arene cavitand 1 was accomplished from 2‐[3,5‐di(tert‐butyl)phenyl]acetaldehyde via formation of the intermediate octol 2 . Such cavitands are known to occur in an open `kite' conformation at low temperature (<213 K) but to adopt a `vase' conformation at elevated temperatures (>318 K). We discovered that protonation of cavitand 1 at room temperature by common acids, such as CF3COOH, also causes reversible switching from `vase' to `kite', and that this conformational change can be conveniently monitored by both 1H‐NMR and UV/VIS spectroscopy. 相似文献
6.
Tatsuya Oshima Masahiro Goto Shintaro Furusaki 《Journal of inclusion phenomena and macrocyclic chemistry》2002,43(1-2):77-86
A series of calixarene carboxylic acid derivatives were synthesized for the extraction of amino acids. A calix[6]arene carboxylic acid derivative showed the highest extractability to the target tryptophan ester. The main driving forcefor the complexation was the interaction between the ammonium cation of the aminoacid and the oxygen atoms of the host molecule. Stripping of amino acids was alsoaccomplished by contacting the organic solution with a fresh acidic solution. Basedon slope and Job method analyses, it was confirmed that the calix[6]arene formsa 1 : 1 complex with the amino acid ester. The structure of the complex between the calix[6]arene and the amino acid was investigated by 1H-NMR and CD spectra. The calix[6]arene includes a guest molecule in the cavity, and the inclusion induces the asymmetrization of the host molecule. This host compound functions as a novel recognition tool for amino acids. 相似文献
7.
Stone MM Franz AH Lebrilla CB 《Journal of the American Society for Mass Spectrometry》2002,13(8):964-974
Non-covalent inclusion complexes formed between amino acids and derivatized calix[6]arenes are observed in MALDI mass spectrometry. The methyl, ethyl, and propyl ester derivatives of calix[6]arene yielded amino acid complexes, while the smaller calix[4]arene analogs did not. Similarly the underivatized calix[6]arene and calix[4]arene did not produce complexes. Amino acid complexes were observed for nearly all 20 amino acids in time-of-flight (TOF) analysis. In Fourier transform mass spectrometry (FTMS) analysis, however, only the most basic amino acids arginine, histidine, and lysine formed stable adducts. The complexes were abundant under matrix-assisted laser desorption ionization (MALDI) conditions, which suggested favorable interactions between host and guest. 相似文献
8.
采用密度泛函理论(DFT)-B3LYP方法在6-31G*基组水平上,对芳香性氨基酸分子体系(Phe, [Phe―H]-,PheH*, Tyr, [Tyr―H]-, TyrH+, Trp, [Trp―H]-和TrpH+)进行结构优化. 在优化所得构型的基础上, 利用含时密度泛函理论(TDDFT)-B3LYP在6-31G*基组上计算了它们的激发态性质,并结合态求和方法研究了它们在二次谐波过程中的二阶极化率值. 同时讨论了二次谐波非线性光学响应的起源及其产生变化的原因. 计算结果表明,相对于中性的氨基酸分子, 去质子化和质子化后的氨基酸分子的二阶极化率值都有明显的增加, 且符合规律Phe < PheH+ < [Phe―H]-和Tyr < TyrH+ < [Tyr―H]-. 通过对它们电极化起源的分析, 我们得到对于中性氨基酸分子, 侧链芳香环上的π→π*跃迁对二阶极化率起主要贡献; 对去质子化和质子化后的氨基酸分子, 吲哚环上的π→π*电荷跃迁和α碳原子相连的氨基和羧基基团内电荷跃迁对二阶极化率起到同样重要的贡献. 相似文献
9.
Arturo Arduini Alessandro Casnati Massimo Fabbi Patrizia Minari Andrea Pochini Anna Rita Sicuri 《Supramolecular chemistry》2013,25(3-4):235-246
Abstract The development of new synthetic methods for the monoalkylation of calix[4]arenes at the lower rim allows the synthesis of a new class of trihydroxamate siderophores. Three chelating hydroxamic acid units are introduced through a sequence of reactions which blocks the macrocycle in the cone conformation. The new ligands obtained form neutral 1:1 complexes (FeL) with iron (III), which are stable in EtOH/H2O 9:1 at pH 2–7. Calix[4]arene bis-crown ethers are prepared by exploiting the selective 1,2-(proximal) functionalization of calix[4]arenes at the lower rim. These ligands are, however, less effective in complexing alkali metal cations compared with the 1,3-calix[4]arene crown-ethers which, in their partial cone structure, offer a better shielding for the complexed cations. Rigid upper rim-bridged calix[4]arenes potentially useful for the inclusion of neutral molecules are prepared by exploiting the selective 1,3-diformylation of calix[4]arene at the upper rim. Finally a new chloromethylation method for calix[4]arenes blocked in the cone conformation is described together with the synthesis of new cavitands. 相似文献
10.
Serkan Erdemir Mustafa Tabakci Mustafa Yilmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2007,59(3-4):197-202
Herein the synthesis and extraction abilities of new d-/l-phenylalaninol substituted p-tert-butylcalix[4]arene triamide derivatives (3 and 4) towards amino acids are reported. These compounds (3 and 4) have been easily synthesized via aminolysis of p-tert-butylcalix[4]arene trimethylester (2) with d-/l-phenylalaninol in methanol-toluen solvent system at one step. The extraction properties of the prepared chiral calix[4]arene
triamide derivatives (3 and 4) towards some selected amino acid methylesters are studied by liquid–liquid extraction. Results show that these chiral calix[4]arene
triamide derivatives (3 and 4) exhibited a good affinity towards all amino acid species without any remarkably discrimination. 相似文献
11.
Joanna Dziemidowicz Dariusz Witt Janusz Rachoń 《Journal of inclusion phenomena and macrocyclic chemistry》2008,61(3-4):381-391
Series of the calix[4]arene phosphonic acids with various substituents at the lower rim was synthesized. Complexing properties of these receptors towards methyl esters of six amino acids strongly depended on the calix[4]arene conformation flexibility. The complex formation processes were monitored using 1H NMR spectroscopy (deuterated phosphate buffer at pD 7.3, 22 °C) and association constant values were evaluated. Inherently mobile calix[4]arene molecule 3 occurred in cone conformation in aqueous solution turned out to be more effective in complexation of the basic amino acids methyl esters compared to the rigid 2 and flexible 4. Mixed 1:2 and 2:1 (host–guest) complexes were observed for compound 1 with all amino acids methyl esters. 相似文献
12.
Purse BW Butterfield SM Ballester P Shivanyuk A Rebek J 《The Journal of organic chemistry》2008,73(17):6480-6488
The use of capsules and cavitands in physical organic chemistry is briefly reviewed, and their application to the study of salt bridges is introduced. Carboxylate/ammonium ion pairs are generated within an environment that more or less surrounds the functional groups within a synthetic fixed introverted solvent sphere. This is provided by cavitands that fold around amines and present them with a carboxylic acid function. Both organic and water-soluble versions were prepared, and their equilibrium affinities with quinuclidine bases were determined by NMR methods. The association constants range from approximately 10(3) M(-1) in water to more than 10(5) M(-1) in organic solvents. Studies of nitrogen inversion and tumbling of [2.2.2]-diazabicyclooctane within the introverted acids also illustrate the strength of the acid-base interactions. The barriers to in-out exchange of several amine guests were determined to be in the range from 15 to 24 kcal mol(-1). Some parallels with enzymes are drawn: the receptor folds around the guest species; presents them with inwardly directed functionality; and provides a generally hydrophobic environment and a periphery of secondary amide bonds. 相似文献
13.
M. Komal Reddy T. Ravinder Reddy K. Raghava Raju 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):313-318
This article describes the reaction of 3,6-diphenyl-thieno[3,2-b]furan-2,5-dione 1 with different amino acids 2a–j in glacial acetic acid which afforded the 2-(2-(3-hydroxy-5-oxo-4-phenylthiophen-2(5H)-ylidene)-2-phenylacetamido)propanoic acid analogues 3a–j and also describes the reaction of 3,6-diphenyl-thieno[3,2-b]thiophene-2,5-dione 4 with different amino acids 5a–e in acidic medium to give 2-(2-(3-mercapto-5-oxo-4-phenylthiophen-2(5H)-ylidene)-2-phenylacetamido)propanoic acid analogues 6a–e. All the compounds have been screened for their anti-inflammatory activity against the carrageenan induced rat paw edema in albino rats. In the primary screening, some of the compounds exhibited appreciable activity. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. 相似文献
14.
Ziganshin M. A. Yakimov A. V. Konovalov A. I. Antipin I. S. Gorbatchuk V. V. 《Russian Chemical Bulletin》2004,53(7):1536-1543
The influence of the calixarene macrocycle size on the thermodynamic parameters of inclusion formation in organic guest vapor—solid host systems was studied in the series of tert-butylcalix[4]arene (1), tert-butylcalix[6]arene (2), and tert-butylcalix[8]arene (3). For this purpose, sorption isotherms of a guest vapor by a solid host were determined using the static method of headspace GC analysis for the systems involving calixarenes 2 and 3 in addition to the earlier obtained data for calixarene 1. Besides, the stoichiometry and decomposition temperatures of saturated clathrates formed in these systems were determined using thermogravimetry. The compositions of some of these clathrates differ substantially from those of clathrates crystallized from a host solution in a liquid guest. For the most guests studied with the thermodynamic activity below 0.6, their uptake by calixarenes 1—3 changes in the series 2 < 1 < 3. As a whole, the trend for each particular parameter of clathrates of hosts 1—3 (stoichiometry, guest activity at 50% saturation of the host) with increasing the size of the calixarene macrocycle is specific for each guest studied. The results obtained are useful for the estimation of receptor properties of calixarenes in quartz microbalance sensors. 相似文献
15.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(1):298-307
The self‐assembly and characterization of water‐soluble calix[4]arene‐based molecular capsules ( 1?2 ) is reported. The assemblies are the result of ionic interactions between negatively charged calix[4]arenes 1 a and 1 b , functionalized at the upper rim with amino acid moieties, and a positively charged tetraamidiniumcalix[4]arene 2 . The formation of the molecular capsules is studied by 1H NMR spectroscopy, ESI mass spectrometry (ESI‐MS), and isothermal titration calorimetry (ITC). A molecular docking protocol was used to identify potential guest molecules for the self‐assembled capsule 1 a?2 . Experimental guest encapsulation studies indicate that capsule 1 a?2 is an effective host for both charged (N‐methylquinuclidinium cation) and neutral molecules (6‐amino‐2‐methylquinoline) in water. 相似文献
16.
Naoya Morohashi Hiroshi Katagiri Takanori Shimazaki Yuichi Kitamoto Shinya Tanaka Chizuko Kabuto 《Supramolecular chemistry》2013,25(12):812-818
Tetraaminothiacalixarene 3, bearing four amino groups instead of the hydroxy groups of p-tert-butylthiacalix[4]arene 2, exhibits inclusion properties different from those of compound 2 towards small organic molecules upon crystallisation from neat solvents or guest solutions. X-ray crystallographic analyses reveal that nitromethane and acetonitrile are included into the cone-shaped cavity of compound 3, as is often seen in inclusion crystals of compound 2, whereas dichloromethane occupies a space between two distal benzene rings of compound 3, adopting a 1,3-alternate conformation. Acetic acid, which forms a dimer, fills a pore surrounded by four host molecules with a pinched cone conformation. Furthermore, guest-free crystals of compound 3 with a 1,3-alternate conformation absorb acetonitrile to give inclusion crystals with the same crystal structure as that obtained by the crystallisation. Thus, compound 3 flexibly changes its conformation according to the structures of guest compounds. 相似文献
17.
A. R. Mustafina I. Ya. Zagidullina V. I. Maslennikova O. S. Serkova T. V. Guzeeva A. I. Konovalov 《Russian Chemical Bulletin》2007,56(2):313-319
New phosphorylated calix[4]resorcinarene and cavitands were synthesized. Their extraction ability toward LaIII, GdIII, and YbIII ions was studied. The cavitands are more efficient extracting agents than octasubstituted calix[4]resorcinarenes. The nature
of substituents at the nitrogen atom at the upper rim and hydrophobic substituents at the lower rim exerts a substantial effect
on the solubility of the extracted complex in chloroform. Coordination of two lanthanide ions with an extragent molecule results
in their efficient but non-selective extraction. The literature and our spectral (31P NMR) data suggested that the ligand in the extracted complex has most probably a “kite” conformation.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 303–308, February, 2007. 相似文献
18.
S. G. Kharchenko A. B. Drapailo O. I. Kalchenko G. D. Yampolska S. V. Shishkina O. V. Shishkin 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):243-248
Abstract Thia- and sulfonyl-calix[4]arene methylphosphonous acids have been synthesized by hydrolysis of corresponding alkyl esters. Host-Guest complexation of the thiacalix[4]arene tetrakis-methylphosphonous acid with a series of 12 amino acids has been investigated by HPLC and molecular modeling methods. Stability constants of the complexes are within 530—10,140 M?1 in water contained solution. 相似文献
19.
Li He Jin-Ping Zeng Da-Hai Yu Hang Cong Yun-Qian Zhang Qian-Jiang Zhu 《Supramolecular chemistry》2013,25(10):619-628
The host–guest interaction of symmetrical α,α′,δ,δ′-tetramethyl-cucurbit[6]uril (TMeQ[6]) with the hydrochloride salts of N,N′-bis(4-pyridylmethyl)-1,6-hexanediamine (P6), N,N′-bis(3-pyridyl-methyl)-1,6-hexanediamine (M6) and N,N′-bis(2-pyridylmethyl)-1,6-hexanediamine (O6) was investigated via single crystal X-ray diffraction, 1H NMR spectroscopy, electronic absorption spectroscopy and fluorescence spectroscopy. Single crystal X-ray diffraction showed that the hexyl moiety of P6 or M6 was incorporated in the cavity of TMeQ[6], while the two pyridylmethyl moieties of O6 were incorporated in the TMeQ[6] cavity in the solid state. The 1H NMR results in aqueous solution revealed that the TMeQ[6]-P6 and TMeQ[6]-M6 host–guest interaction systems produce a kinetic dumbbell-shaped inclusion complex at the initial stage and then an equilibrium pseudorotaxane-shaped inclusion complex as the only product after heating. However, only the pseudorotaxane-shaped inclusion complex was observed for the TMeQ[6]-O6 host–guest interaction system. Aqueous absorption spectrophotometric analysis showed that the dumbbell-shaped inclusion complexes were stable at pH 5.6, had a host–guest ratio of 2:1 and formed quantitatively at ~1011 l2/mol2 for the TMeQ[6]-M6 and TMeQ[6]-O6 systems. The transformation from dumbbell to pseudorotaxane-shaped inclusion complexes for the TMeQ[6]-P6 and TMeQ[6]-M6 host–guest systems yielded activation energies of 59.35 ± 1.55 and 78.7 ± 3.45 kJ/mol, respectively. The pseudorotaxane-shaped inclusion complexes were stable at pH 5.6, had a host–guest ratio of 1:1 and formed quantitatively at ~107 l/mol for the TMeQ[6]-M6 and TMeQ[6]-P6 systems. 相似文献
20.
Dr. Pravat Mondal Dr. Ephrath Solel Dr. Natalia Fridman Prof. Ehud Keinan Prof. Ofer Reany 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(58):13336-13343
Bambusurils (BUs) are known to be rigid cavitands that feature an extended, jigger-like conformation, and the BU[6]s strongly bind anions within their hydrophobic cavity. These features are not necessarily shared by the family of perthio-BUs. This study reveals that perthio-BUs assume a compact conformation and perthio-BU[6]s are poor anion binders, crystallizing as anion-free species from solutions containing halide salts. Computational studies show that the equatorial sulfur atoms compete against guest anions for binding with the glycoluril methine groups via strong van der Waals (vdW) attractive interactions. These competitive contacts not only account for the diminished anion-binding of perthio-BUs, but also explain their compact conformation. The semithio- and perthio-BU[4]s form linear coordination polymers with HgII in the solid-state regardless of their intrinsic molecular conformation. The strong involvement of sulfur atoms in intramolecular interactions differentiates the equatorial from the axial (peripheral) heteroatoms, thus offering chemoselective and regioselective transformations. 相似文献