NMR diffusion spectroscopy as a measure of host-guest complex association constants and as a probe of complex size.
J Org Chem
; 66(21): 6891-5, 2001 Oct 19.
Article
en En
| MEDLINE
| ID: mdl-11597206
The complexes of cyclohexylacetic acid and cholic acid with beta-cyclodextrin were studied by NMR diffusion coefficient measurements. The diffusion coefficient of the 1:1 cyclohexylacetic acid/beta-cyclodextrin complex, K(a) = 1800 +/- 100 M(-1), is slightly slower (3.23 +/- 0.07 x 10(-6) cm(2) s(-1)) than that of beta-cyclodextrin (3.29 +/- 0.07 x 10(-6) cm(2) s(-1)). The diffusion coefficient of the 1:1 cholic acid/beta-cyclodextrin complex, K(a) = 5900 +/- 800 M(-1), is significantly slower (2.93 +/- 0.07 x 10(-6) cm(2) s(-1)) than that of beta-cyclodextrin. The results indicate that caution should be exercised when studying host-guest complexation by the so-called 'single point' technique. A novel data treatment is introduced which takes into account the diffusion behavior of all of the species when determining K(a). Experimentally determined diffusion coefficients of complexes are also a useful probe of the size of host-guest complexes.
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Colección:
01-internacional
Base de datos:
MEDLINE
Tipo de estudio:
Risk_factors_studies
Idioma:
En
Revista:
J Org Chem
Año:
2001
Tipo del documento:
Article
Pais de publicación:
Estados Unidos