Inclusion Compounds. XIX.<sup>1a</sup> The Formation of Inclusion Compounds of α-Cyclodextrin in Aqueous Solutions. Thermodynamics and Kinetics

Cramer, Friedrich; Saenger, Wolfram; Spatz, Hanns–Christof

doi:10.1021/ja00977a003

Cited by 728 publications

(319 citation statements)

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“…We observe in Fig. 2b [P] 1 Ddisp,max ϭ 7.5 mM and [P] 2 Ddisp,max ϭ 1.1 mM; 1͞K 1 ϭ 5.8 mM and 1͞K 2 ϭ 1.0 mM were, respectively, anticipated from the literature values. These results provide the first observation in chemistry of dispersion in an oscillating field (10,(12)(13)(14)(15).…”

Section: Resultssupporting

confidence: 74%

“…In relation with Fig. 2a, we (2,3) were used to determine the field period fixed during the whole series of experiments involving a given dye; we chose the specific value T ϭ 3.212͞k i b given in Eq. 3 (90 s for C 1 at 298 K and 31 s for C 2 at 283 K).…”

Section: Resultsmentioning

confidence: 99%

“…1) (2)(3)(4)(5). In a classic affinity chromatography, the average velocity v i of a mixture component is ruled by the equilibrium association constant K i ϭ k i f ͞k i b , where the rate constants k i f and k i b are, respectively, associated to the forward and the backward reaction 1: Those components that do not react are easily discarded, whereas the others are separated according to their affinity for the target.…”

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confidence: 99%

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Molecular sorting by stochastic resonance

Alcor

Croquette

Jullien

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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To sort a targeted species from a mixture, we introduce a procedure that relies on the enhancement of its effective diffusion coefficient. We use the formation of a host-guest complex between ␣-cyclodextrin and a dye to evidence the dye dispersion when the medium is submitted to an oscillating field. In particular, we demonstrate that the effective diffusion coefficient of the dye may be increased far beyond its intrinsic value by tuning the driving field frequency in the stochastic resonance regime. We use this effect to selectively sort from a mixture a dye that is addressed by its rate constants for association with ␣-cyclodextrin.S orting molecules from a mixture is an essential issue in chemistry (1). A radical answer consists in using ''universal'' chromatography columns, which would ideally resolve all of the mixture components. Then the counterpart is to reach a sufficient resolution. Affinity chromatography is another approach that can be envisaged when one is interested in extracting components that exhibit a given reactivity. For example, one can search in a mixture {C i } for a free molecule C i that targets a receptor P to give a bound state C i P according to the reactionIn the following, we consider association of dyes (C i ; i ϭ 1 or 2) with ␣-cyclodextrin (P) to form host-guest complexes (C i P) ( b are, respectively, associated to the forward and the backward reaction 1: Those components that do not react are easily discarded, whereas the others are separated according to their affinity for the target. With respect to ''universal'' columns, selective addressing with a chemical reaction reduces the mixture to a smaller pool, making separation less resolution-demanding.To enlarge selectivity and facilitate molecular sorting that implies control of the motion of the mixture components, we propose a chromatography procedure that is related to affinity chromatography but that determines sorting by the kinetics of both binding and release, as described by k i f and k i b . In fact, the rate constants of the mixture components often differ to a larger extent than their association constants. For example, the dyes C 1 and C 2 exhibit a similar affinity for the ␣-cyclodextrin P: K 1 ͞K 2 ϭ 0.34 at 283 K (2, 3). In contrast, k 1 f ͞k 2 f ϭ 0.021 and k 1 b ͞k 2 b ϭ 0.063 at the same temperature. A chromatography based on differences in rate constants may therefore improve selectivity in comparison with traditional approaches that rely on differences in equilibrium properties (1, 6) (e.g., association constants). In addition, discrimination among components that exhibit the same association constant but different rate constants becomes possible.To simultaneously emphasize on kinetic properties and induce molecular motion, we apply a uniform time-periodic field (e.g., an electric field) with zero average value having a period tuned to the dynamics of the reaction involved in selective addressing (here reaction 1) (7-9). We predicted that field-sensitive species C i submitted to reaction 1 with receptor P in...

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Molecular sorting by stochastic resonance

Alcor

Croquette

Jullien

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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“…All complexes were isolated as the hexafluorophosphate salts by column chromatography or preparative thin layer chromatography, and were obtained as microcrystalline solids in good yields. Their molecular structures were unambiguously assigned by using 1 H, 13 C and 2D homo-and heteronuclear NMR spectroscopy, electrospray mass spectrometry and elemental analysis (the synthesis of rac-1 has been reported previously). [23] Both dyes analyzed by ESI-MS gave an intense molecular peak with the expected isotopic profile corresponding to the loss of two PF6 -counter anions assigned to a doubly charged species, and the expected profile for the singly charged species corresponding to the loss of one PF6 -anion.…”

Section: Molecular Synthesismentioning

confidence: 99%

“…[12] One of the earliest examples of dye encapsulation inside a CD was a report by Cramer and coworkers who described the inclusion of an azo dye within the cavity of α-CD. [13] Various examples can also be found where CDs form host-guest structures with electron relays that help stabilize intermediate photoproducts against back-electrontransfer reactions, in particular when using methyl viologen derivatives. [14] The use of CDs for localizing metal-based molecular complexes is less established and zeolites are the preferred choice for their encapsulation.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Photostability of a Ruthenium(II) Polypyridyl Complex under Highly Oxidizing Aqueous Conditions by Its Partial Inclusion into a Cyclodextrin

Farràs

Waller

Benniston

2015

Chemistry A European J

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Abstract:The complex [Ru(bpy)2L] 2+ , where bpy = 2,2'-bipyridine, L = 4-(phenylethynyl)-2,2'-bipyridine, was prepared in its racemic and resolved forms (and . The phenylethynyl unit on the bipyridine for the complex acts as a binding site for -cyclodextrin in water (1:1 complex, K = 3390 M -1 ) or -cyclodextrin (2:1 complex, K1 = 887 M -1 , K2 = 8070 M -1 ). The presence of the cyclodextrin provides partial protection to the complex under light-activated water oxidation conditions.

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Indirect Fluorimetric Detection of Cyclodextrins via Postcolumn Mixing with 2-p-Toluidinyl-6-naphthalenesulfonate in Liquid Chromatography

Takeuchi

Miwa

1999

J. High Resol. Chromatogr.

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Inclusion Compounds. XIX.^1a The Formation of Inclusion Compounds of α-Cyclodextrin in Aqueous Solutions. Thermodynamics and Kinetics

Cited by 728 publications

References 2 publications

Molecular sorting by stochastic resonance

Molecular sorting by stochastic resonance

Enhanced Photostability of a Ruthenium(II) Polypyridyl Complex under Highly Oxidizing Aqueous Conditions by Its Partial Inclusion into a Cyclodextrin

Indirect Fluorimetric Detection of Cyclodextrins via Postcolumn Mixing with 2-p-Toluidinyl-6-naphthalenesulfonate in Liquid Chromatography

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Inclusion Compounds. XIX.1a The Formation of Inclusion Compounds of α-Cyclodextrin in Aqueous Solutions. Thermodynamics and Kinetics

Cited by 728 publications

References 2 publications

Molecular sorting by stochastic resonance

Molecular sorting by stochastic resonance

Enhanced Photostability of a Ruthenium(II) Polypyridyl Complex under Highly Oxidizing Aqueous Conditions by Its Partial Inclusion into a Cyclodextrin

Indirect Fluorimetric Detection of Cyclodextrins via Postcolumn Mixing with 2-p-Toluidinyl-6-naphthalenesulfonate in Liquid Chromatography

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Inclusion Compounds. XIX.^1a The Formation of Inclusion Compounds of α-Cyclodextrin in Aqueous Solutions. Thermodynamics and Kinetics