Complexes of carbohydrates with metal cations. VIII. Lanthanide-induced shifts in the P.M.R. spectra of some methyl glycosides and 1,6-anhydrohexoses

Angyal, S. J.; Greeves, Diane; Littlemore, Linda; Pickles, VA

doi:10.1071/ch9761231

Cited by 27 publications

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“…Solution Coordination Studies. In 1976 S. J. Angyal showed 28 that the kinetic constant of the equilibrium (k c ) in the complexation of cations by polyols in water is high on the NMR time scale (k c , 10 -5 s) and that "limiting shifts" which would correspond to the proton chemical shift of the complex could not be determined directly by simple addition of large quantities of the inorganic salts. This is particularly true when several sites of different complexing abilities are present (see for example cis-inositol).…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Structure, and Solution Studies of Cyclohexantriol Complexes of Europium(III)

et al. 1999

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cis,cis-1,3,5-Trihydroxycyclohexane (L(1)()) and cis,cis-1,2,3-trihydroxycyclohexane (L(2)()) have been considered as ligands for the complexation of europium(III) in organic solvents. Three complexes were prepared and characterized by X-ray diffraction analysis, microanalysis, electrospray mass spectrometry, and proton NMR. Depending on the europium(III)-to-ligand ratio, ML or ML(2) complexes were formed in organic solution. Complexes formed with ligand L(2)() are stable in methanol solution, while those obtained from L(1)() are stable only in nonprotic solvents. This difference is related to the amount of energy involved in the necessary chair-chair conversion prior to complexation of the europium(III) ion. In the solid state the coordination sphere including in each case two L(1)()or L(2 )()molecules( )()as tridentate ligands, is completed by a bidentate nitrate anion and one molecule of water in 1, [Eu(L(1))(2)(NO(3))(H(2)O)](NO(3))(2), two monodentate triflate anions and one molecule of water in 2, [Eu(L(1))(2)(OTf)(2)(H(2)O)](OTf), and a bidentate and a monodentate nitrate anion in 3, [Eu(L(2))(2)(NO(3))(2)](NO(3)). Many strong H bonds are present in the crystalline network with H.O distances between 1.77 and 2.301 Å. Proton NMR studies have shown that a moderate lowering of the temperature is sufficient to observe the different species present in solution, the proportions of which depend on the metal-to-ligand ratio. Conductometric studies have also provided indication about the number of coordinated anion in methanol and acetonitrile solutions.

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Section: Resultsmentioning

confidence: 99%

Synthesis, Structure, and Solution Studies of Cyclohexantriol Complexes of Europium(III)

et al. 1999

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“…To prove the suggested location of the complexing site, we investigated the shifts caused by lanthanide ions in the 'H NMR spectra (12). Addition of europium salts caused a small upfield shift of all of the signals in the spectrum of the PP,PP isomer; however, praseodymium salts shifted only the signal of H 3,3' *Superscripts refer to the symmetry transformations:…”

Section: Introductionmentioning

confidence: 99%

Complexes of carbohydrates with metal cations. XVI•Di-D-fructose and di-L-sorbose dianhydrides

Angyal¹,

Craig²,

Defaye³

et al. 1990

Can. J. Chem.

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. 68, 1140(1 990).Di-D-fructose 2', 1:2,11-dianhydrides form complexes with metal cations if the two anomeric carbon atoms have the same configuration. Such anomers have the central 1,4-dioxane ring in a flexible form; complex formation involves 0-1, 0-1 ', 0-3, and 0-3', as confirmed by the X-ray crystal structure of the strontium complex of the P,P-dipyranose anomer. The a,p-anomers, and dianhydrides containing only furanose rings, do not form such complexes.Key words: difructose dianhydrides, complex formation with cations, crystal structure of complex, chromatographic separation on ion-exchange resins.STEPHEN JOHN ANGYAL, DONALD CHADWICK CRAIG, JACQUES DEFAYE et AND&€ GADELLE. Can. J. Chem. 68, 1140 (1990).Les 2', 1:2,11-dianhydrides du di-D-fructose forment des complexes avec les cations mCtalliques si les deux atomes de carbone anomtriques possedent la m&me configuration. Dans de tels anomeres, le cycle 1,4-dioxane central existe dans une conformation flexible; comrne il a Ct C Ctablie par diffraction des rayons-X sur le complexe de strontium de l'anomere P,P-dipyranose, la formation de complexe implique les atomes 0 -1,O-l ' , 0 -3 et 0-3'. Les anomeres a , P ainsi que les dianhydrides ne contenant que des cycles furanoses ne forment pas de tels complexes.Mots cle's : dianhydrides du difructose, formation de complexes avec les cations, structure cristalline du complexe, stparation par chromatographie sur des rCsines Cchangeuses d'ions.[Traduit par la revue] IntroductionThe reaction of D-fructose or inulin with strong aqueous acids or with anhydrous hydrogen fluoride yields a mixture of difructose dianhydrides of which nine diastereomers have been isolated and characterized (2-5). To seDarate them. chromatographic methods are emplo$ed; five of tde anhydrides have been separated from each other by reverse-phase high-performance liquid chromatography (HPLC) (6). It seemed desirable to ascertain whether chromatography on cation-exchange resins in the calcium form (7) would be suitable for their separation. In principle, this method does not seem to offer much promise because fructosides do not form strong complexes with cations (8): fructofuranosides do not complex, a-fructopyranosides form only very weak complexes at 0-4-0-5, and p-fructopyranosides weak ones at 0-4-0-5 and 0-2-0-3. However, complexing involving hydroxyl groups of both fructose moie-

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“…The third step, finally, leads to a species in which the cation is complexed to three oxygens of hydroxyl or ether groups of the carbohydrates, as has been discussed in the literature. 11 The first step of reaction scheme 4 may contribute a highfrequency relaxation process (index "0") in the solutions, above our frequency range of measurements. Indeed, up to 500 MHz, the presence of an upper relaxation process was undetectable.…”

Section: Discussionmentioning

confidence: 80%

“…The first step leads to a solvent separated species, Ca 2+ ···ch sometimes symbolized by Ca 2+ (H 2 O)ch, whereas the second step results in a monodentate contact species, in which the cation interacts with the lone electrons of preferably one carbohydrate oxygen. The third step, finally, leads to a species in which the cation is complexed to three oxygens of hydroxyl or ether groups of the carbohydrates, as has been discussed in the literature …”

Section: Discussionmentioning

confidence: 99%

Microsecond to Subnanosecond Molecular Relaxation Dynamics of the Interaction of Ca²⁺ with Some Carbohydrates in Aqueous Solution

et al. 1998

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Ultrasonic absorption spectra in the frequency range 1−500 MHz are reported for solutions of methyl-β-d-arabinopyranoside and of 1,6-anhydro-β-d-glucopyranoside, both with and without added Ca2+ and Ba2+ ions. These carbohydrates have been chosen because neither monosaccharide shows any relaxation process, over the same frequency range, in salt-free aqueous solutions. Spectra for both carbohydrates in aqueous solution with added Ca(ClO4)2, CaCl2, or Ba(ClO4)2 can be represented by an asymptotic high-frequency contribution and a Debye relaxation term centered between 50 and 200 MHz, corresponding to a process with a relaxation time of approximately 3−4 ns. Spectra for solutions of Ca(ClO4)2 + 1,6-anhydro-β-d-glucopyranoside also exhibit a second relaxation process at lower frequencies, with a relaxation time of approximately 30 ns. These results clearly indicate cation−carbohydrate complex formation. The observed relaxation terms are interpreted as a modified Eigen−Winkler-type multistep process, associated with formation of monodentate cation−carbohydrate complexes and, where possible, subsequent rearrangement to tridentate complexes.

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Complexes of carbohydrates with metal cations. VIII. Lanthanide-induced shifts in the P.M.R. spectra of some methyl glycosides and 1,6-anhydrohexoses

Cited by 27 publications

References 0 publications

Synthesis, Structure, and Solution Studies of Cyclohexantriol Complexes of Europium(III)

Synthesis, Structure, and Solution Studies of Cyclohexantriol Complexes of Europium(III)

Complexes of carbohydrates with metal cations. XVI•Di-D-fructose and di-L-sorbose dianhydrides

Microsecond to Subnanosecond Molecular Relaxation Dynamics of the Interaction of Ca²⁺ with Some Carbohydrates in Aqueous Solution

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Complexes of carbohydrates with metal cations. VIII. Lanthanide-induced shifts in the P.M.R. spectra of some methyl glycosides and 1,6-anhydrohexoses

Cited by 27 publications

References 0 publications

Synthesis, Structure, and Solution Studies of Cyclohexantriol Complexes of Europium(III)

Synthesis, Structure, and Solution Studies of Cyclohexantriol Complexes of Europium(III)

Complexes of carbohydrates with metal cations. XVI•Di-D-fructose and di-L-sorbose dianhydrides

Microsecond to Subnanosecond Molecular Relaxation Dynamics of the Interaction of Ca2+ with Some Carbohydrates in Aqueous Solution

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Microsecond to Subnanosecond Molecular Relaxation Dynamics of the Interaction of Ca²⁺ with Some Carbohydrates in Aqueous Solution