10016-20-3Relevant articles and documents
NMR Detection of Simultaneous Formation of [2]- and [3]Pseudorotaxanes in Aqueous Solution between α-Cyclodextrin and Linear Aliphatic α,ω-Amino acids, an α,ω-Diamine and an α,ω-Diacid of Similar Length, and Comparison with the Solid-State Structures
Eliadou, Kyriaki,Yannakopoulou, Konstantina,Rontoyianni, Aliki,Mavridis, Irene M.
, p. 6217 - 6226 (1999)
The interactions of 11-aminoundecanoic acid (1), 12-aminododecanoic acid (2), 1,12-diaminododecane (3), and 1,13-tridecanoic diacid (4) with α-cyclodextrin (αCD) were studied in aqueous solution by NMR spectroscopy. The association modes were established with titration and continuous variation plots, variable temperature NMR spectra, and dipolar interactions as recorded in 2D ROESY spectra. The studies were carried out at pH 7.3 and 13.6. These long, linear bifunctional molecules were found to form simultaneously [2]- and [3]pseudorotaxanes with αCD in the aqueous solution. At the higher pH the 1:1 adducts were present at concentrations higher than at the neutral pH. The longer guests formed complexes enriched in the 2:1 constituent at both pH values. There were clear indications that the [2]pseudorotaxanes are present in two isomeric forms. The presence of isomers also in the [3]pseudorotaxanes was not ruled out. Various exchange rate regimes were observed; clearly in neutral solutions the formation of the 1:1 complexes was fast in the NMR time scale, whereas the threading of a second αCD ring was a slower process. In the solid state, the adduct of αCD/2 had the structure of a [3]pseudorotaxane, in accordance with previously solved crystal structures of αCD/3 and βCD/4. The species in solution, in contrast with those present in the solid state, are therefore of varying nature, and thus the frequently and conveniently assumed 1:1 stoichiometry in similar systems is an oversimplification of the real situation.
Thermodynamic and nuclear magnetic resonance study of the reactions of α- and β-cyclodextrin with acids, aliphatic amines, and cyclic alcohols
Rekharsky, Mikhail V.,Mayhew, Martin P.,Goldberg, Robert N.,Ross, Philip D.,Yamashoji, Yuko,Inoue, Yoshihisa
, p. 87 - 100 (1997)
Titration calorimetry was used to determine equilibrium constants and standard molar enthalpy, Gibbs energy, and entropy changes for the reactions of a series of acids, amines, and cyclic alcohols with α- and β-cyclodextrin. The results have been examined in terms of structural features in the ligands such as the number of alkyl groups, the charge number, the presence of a double bond, branching, and the presence of methyl and methoxy groups. The values of thermodynamic quantities, in particular the standard molar Gibbs energy, correlate well with the structural features in the ligands. These structural correlations can be used for the estimation of thermodynamic quantities for related reactions. Enthalpy-entropy compensation is evident when the individual classes of substances studied herein are considered, but does not hold when these various classes of ligands are considered collectively. The NMR results indicate that the mode of accommodation of the acids and amines in the α-cyclodextrin cavity is very similar, but that the 1-methyl groups in 1-methylhexylamine and in 1-methylheptylamine and the N-methyl group in N-methylhexylamine lie outside the α-cyclodextrin cavity. This latter finding is consistent with the calorimetric results. Many of the thermodynamic and NMR results can be qualitatively understood in terms of van der Waals forces and hydrophobic effects.
Volume Change on Complex Formation Between Anions and Cyclodextrins in Aqueous Solution
Hoeiland, H.,Hald, L.H.,Kvammen, O.J.
, p. 775 - 784 (1981)
Partial molal volume changes during complex formation between SCN(1-), I(1-), and ClO4(1-) and α- and β-cyclodextrin have been determined by two independent methods of measurements; one based on density measurement and subsequent calculation of apparent molal volumes, the other on differentiating the association constants with respect to pressure.Results from the two methods are in good agreement.Negative volume changes were observed for complex formation between the anions and α-cyclodextrin while zero or slightly positive values were observed for complex formation with β-cyclodextrin.The result is consistent with the idea that the anions do not become dehydrated as they form complexes with cyclodextrins.
Catalysis of ester aminolysis by cyclodextrins. The reaction of alkylamines with p-nitrophenyl alkanoates
Gadosy,Boyd,Tee
, p. 6879 - 6889 (2000)
The effects of four cyclodextrins (α-CD, β-CD, hydroxypropyl-β-CD, and γ-CD) on the aminolysis of p-nitrophenyl alkanoates (acetate to heptanoate) by primary amines (n-propyl to n-octyl, isobutyl, isopentyl, cyclopentyl, cyclohexyl, benzyl) in aqueous solution have been investigated. Rate constants for amine attack on the free and CD-bound esters (k(N) and k(cN)) have ratios (k(cN)/k(N)) varying from 0.08 (retardation) to 180 (catalysis). For the kinetically equivalent process of free ester reacting with CD-bound amine (k(Nc)), the ratios k(Nc)/k(N) vary from 0.2 to 28. Either way, there is evidence of catalysis in some cases and retardation in others. Changes in reactivity parameters with structure indicate more than one mode of transition state binding to the CDs. Short esters react with short alkylamines by attack of free amine on the ester bound by its aryl group, but for longer amines, free ester reacts with CD-bound amine. Reaction of long esters with long amines, which is catalyzed by β-CD and γ-CD, involves inclusion of the alkylamino group and possibly the ester acyl group. The larger cavity of γ-CD may allow the inclusion of the ester aryl group, as well as the alkylamino group, in the transition state. Reaction between an ester bound to the CD by its acyl group and free amine appears not to be important.
Induced circular dichroism and UV-VIS absorption spectroscopy of cyclodextrin inclusion complexes: Structural elucidation of supramolecular azi-adamantane
Krois, Daniel,Brinker, Udo H.
, p. 11627 - 11632 (1998)
The first induced circular dichroism (ICD) analyses of diazirineγyciodextrin inclusion complexes are reported. The stoichiometries and association constants of the guestηost complexes with α-, β-, and γ- cyclodextrin were determined. In addition, with the α-cyclodextrin complex, UV-vis spectroscopy of water-ethanol solutions showed remarkable fine structure, probably indicating that the diazirine experiences a nonpolar microenvironment. These analytical methods provide details about the architecture and nature of these supramolecular carbene precursors.
ENZYMATIC SYNTHESIS OF CYCLODEXTRINS WITH α-GLUCOSYLFLUORIDE AS A SUBSTRATE FOR CYCLODEXTRIN-α(1->4)GLUCOSYLTRANSFERASE
Treder, Wolfgang,Thiem, Joachim,Schlingmann, Merten
, p. 5605 - 5608 (1986)
By use of immobilized cyclodextrin-α(1->4)glucosyltransferase α-glucosylfluoride is transformed in high yield predominantly into cyclodextrins and maltooligomers as side products.
Suitability and limitations of methods for characterisation of activity of malto-oligosaccharide-forming amylases
Duedahl-Olesen, Lene,Haastrup Pedersen, Lars,Lambertsen Larsen, Kim
, p. 109 - 119 (2000)
The suitability and limitations of essential methods and reference substrates used for characterisation of activity of amylolytic enzymes is investigated. Saccharogenic, chromogenic and chromatographic methods are included. The results are discussed in relation to the measurement of reaction rates, determination of action mode and product specificity and the impact on identification and nomenclature of malto-oligosaccharide-forming amylases. An accurate determination of reaction rates using the saccharogenic methods strongly depends on the degree of polymerisation (DP) of the standards used and the hydrolysis products formed by the amylase. Particularly the use of glucose as standard can lead to overestimates due to the differences in the reducing potential of glucose and malto-oligosaccharides. The reliability of the chromogenic methods for determination of action mode depends on the DP of the substrate and the specificity of the amylase. For a characterisation of the starch hydrolysis products and the variation in the DP during hydrolysis, high performance anion-exchange chromatography with pulsed amperometric detection provided a fast and reliable method. A literature survey revealed varying and inconsistent use of nomenclature of malto-oligosaccharide forming amylases. Therefore a systematic approach identifying three main classes of activity is suggested using not only the mode of action and the DP of the major product but also the stage of hydrolysis at which this product is formed. (C) 2000 Elsevier Science Ltd.
Spectroscopic Studies on Exchange Properties in Through-Ring Cyclodextrin Complexes of Carbazole-Viologen Linked Compounds: Effects of Spacer Chain Length
Yonemura, Hiroaki,Kasahara, Motohiro,Saito, Hide,Nakamura, Hiroshi,Matsuo, Taku
, p. 5765 - 5770 (1992)
Analysis of 1H NMR spectra (400 MHz) revealed a novel mode of interaction between cyclodextrin (CD) and carbazole-viologen linked compounds (CACnV), where the spacer chain was consisted of n methylene units (n = 4, 6, 8, 10, and 12).In the case of α-CD, the complexed species lived long enough to afford distinct proton signals, when the spacer chain was relatively long (n >/= 8).As to CAC12V, the equilibrium constant for the 1:1 complex was 4.9 * 104 M-1 at 30 deg C and coalescence temperatures for the proton signals exceeded 100 deg C.Clear NOEs were observedto prove strong interaction between the protons in the CD cavity and the spacer methylene groups of CAC12V.The spacer was concluded to be encased in the cavity of α-CD.In the case of β-CD, essentially the same "through-ring CD complex" was formed.The line shape analysis indicated that the free energies of activation at 70 deg C for complexation and decomplexation were 11.6 and 17.2 kcal/mol, respectively.Activation parameters for the α-CD complexes were evaluated by the rate of disappearance of intramolecular charge-transfer absorption (420 nm) on the addition of α-CD.The free energy of activation for decomplexation was found to exceed 22 kcal/mol in the α-CD complexes for CACnV (n = 8, 10, and 12).The viologen moiety of CACnV was concluded to be the site of entrance for forming "through-ring CD compex", and the large activation energies were ascribed to dehydration of viologen units to go through the CD cavity.
Synthesis of a Cyclodextrin Heterodimer Having α- and β-Cyclodextrin Units and Its Cooperative and Site-Specific Binding
Wang, Yong,Ueno, Akihiko,Toda, Fujio
, p. 167 - 170 (1994)
A cyclodextrin heterodimer, which has α- and β-cyclodextrin units as two different receptor sites, was prepared.It showed cooperative and site-specific binding to isoamyl p-dimethylaminobenzoate with the alkyl group included in the β-cyclodextrin cavity while dimethylaminobenzene moiety partially included in the α-cyclodextrin cavity.This binding mode was substantiated by the fact that the TICT emission of this guest is greatly enhanced by the cyclodextrin heterodimer.
Selective synthesis of a [3]rotaxane consisting of size-complementary components and its stepwise deslippage
Akae, Yosuke,Okamura, Hisashi,Koyama, Yasuhito,Arai, Takayuki,Takata, Toshikazu
supporting information; experimental part, p. 2226 - 2229 (2012/06/30)
An α-cyclodextrin-based size-complementary [3]rotaxane with an alkylene axle was selectively synthesized in one pot via an end-capping reaction with 2-bromophenyl isocyanate in water. Thermal degradation of the [3]rotaxane product yielded not only the ori
