NMR diffusion as a novel tool for measuring the association constant between cyclodextrin and guest molecules

Wimmer, Reinhard; Aachmann, Finn Lillelund; Larsen, Kim Lambertsen; Petersen, Steffen B.

doi:10.1016/s0008-6215(02)00066-6

Cited by 85 publications

(76 citation statements)

References 18 publications

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“…Reorientational correlation times can be extracted from the cross-relaxation rates σ ij , which, in the initial rate approximation, [4] are functions of the interproton distance r ij and of the reorientational correlation time τ cij [Equation (7) in which γ, R and ω represent the gyromagnetic ratio, the reduced Planck's constant and the proton Larmor frequency, respectively]. (7) In the fast (ω 2 τ c 2 ϽϽ 1) and slow (ω 2 τ c 2 ϾϾ 1) motion regions, σ ij can be approximated to the two simple Equations (8) and (9). (8) (9) Having determined the cross-relaxation rate of a proton pair at a fixed distance [r ij known in Equations (8) and (9)], τ cij can be calculated.…”

Section: Self-association Phenomenamentioning

confidence: 99%

NMR and Computational Investigations of the Chiral Discrimination Processes Involving a Cyclic Tetraamidic Chiral Selector

et al. 2011

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The chiral recognition mechanism of a macrocyclic tetraamidic receptor for the enantiomers of N-(3,5-dinitrobenzoyl) valine-N-hexylamide has been investigated in detail through a combination of NMR spectroscopy and molecular modeling studies. Intra- and intermolecular ROE effects provided information on the conformations of the free and complexed partners, and also on their relative arrangement in solution during complexation. Molecular mechanics calcula-tions and molecular docking studies gave results in agreement with the spectroscopic data, correctly reproducing the relative stability of the two diastereoisomeric complexes. A stereochemical model for the complexed species is presented in which hydrogen-bonding interactions between amide fragments drive the association process, and the enantioselectivity is modulated by aromatic–aromatic interactions and steric hindrance

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Section: Self-association Phenomenamentioning

confidence: 99%

NMR and Computational Investigations of the Chiral Discrimination Processes Involving a Cyclic Tetraamidic Chiral Selector

et al. 2011

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“…Changes in relaxation times have also been measured [128,129], but the interpretation of the data is model dependent and less straightforward than data from self-diffusion measurements, which are conceptually easier and often nowadays experimentally easy to obtain. NMR diffusometry has been used to study inclusion complexes between cyclodextrin and different substrates [130][131][132][133]. The selfdiffusion measurements are in principle applicable to any systems as long as the free and complexed guests (please note that on account of the rapid exchange on the NMR time scale, average diffusion coefficients for both the guest and for the CD are obtained)…”

mentioning

confidence: 99%

The formation of host–guest complexes between surfactants and cyclodextrins

Valente

Söderman

2014

Advances in Colloid and Interface Science

180

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Cyclodextrins are able to act as host molecules in supramolecular chemistry with applications ranging from pharmaceutics to detergency. Among guest molecules surfactants play an important role with both fundamental and practical applications. The formation of cyclodextrin/surfactant host-guest compounds leads to an increase in the critical micelle concentration and in the solubility of surfactants. The possibility of changing the balance between several intermolecular forces, and thus allowing the study of, e.g., dehydration and steric hindrance effects upon association, makes surfactants ideal guest molecules for fundamental studies. Therefore, these systems allow for obtaining a deep insight into the host-guest association mechanism. In this paper, we review the influence on the thermodynamic properties of CD-surfactant association by highlighting the effect of different surfactant architectures (single tail, double-tailed, gemini and bolaform), with special emphasis on cationic surfactants. This is complemented with an assessment of the most common analytical techniques used to follow the association process. The applied methods for computation of the association stoichiometry and stability constants are also reviewed and discussed; this is an important point since there are significant discrepancies and scattered data for similar systems in the literature.In general, the surfactant-cyclodextrin association is treated without reference to the kinetics of the process. However, there are several examples where the kinetics of the process can be investigated, in particular those where volumes of the CD cavity and surfactant (either the tail or in special cases the head group) are similar in magnitude.This will also be critically reviewed.

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“…This result may be a consequence of the low molar ratio for ABZ and because aliphatic guests or included compounds with low association constants normally have negligible chemical dislocations (Wimmer et al, 2002).…”

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confidence: 99%

Enhancement of solubility of albendazole by complexation with β-cyclodextrin

Moriwaki

Costa

Ferracini

et al. 2008

Braz. J. Chem. Eng.

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-A high dosage of albendazole (ABZ) is required for treating systemic helminthe infections because of its low solubility. Aiming at increasing ABZ solubility, complexation with beta-cyclodextrin ( -CD) using aqueous and acetic acid solutions as ABZ solubilizer was studied. In aqueous -CD, complexation increased solubility 53.4 times, giving a complex equilibrium constant of 1266 L mol -1 with a maximum ABZ concentration of 276 µmol L -1 for 16.3 mmol L -1 -CD. For complexation in 1.05 mol L -1 acetic acid, UV absorbance spectra and 1 H-NMR analysis confirmed complex formation. The UV absorbance of ABZ/acid acetic/ -CD solutions was modeled by the formation of two complexes with molar ratios 1:1 and 1:2 ABZ: -CD. When neutralized with NaOH these solutions did not form precipitates only for the ABZ: -CD molar ratios of 1:8 and 1:10, showing that ABZ solubility could be increased 306 times. Results show that high -CD molar ratios hold ABZ in solution by complexation enhanced by the acetate anion.

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NMR diffusion as a novel tool for measuring the association constant between cyclodextrin and guest molecules

Cited by 85 publications

References 18 publications

NMR and Computational Investigations of the Chiral Discrimination Processes Involving a Cyclic Tetraamidic Chiral Selector

NMR and Computational Investigations of the Chiral Discrimination Processes Involving a Cyclic Tetraamidic Chiral Selector

The formation of host–guest complexes between surfactants and cyclodextrins

Enhancement of solubility of albendazole by complexation with β-cyclodextrin

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