ISSN:
1573-1111
Keywords:
Cyclodextrin
;
diflunisal
;
equilibrium
;
spectrophotometry
;
nuclear magnetic resonance
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The complexation of the diflunisal anion (DF) by γ-cyclodextrin (γCD) and permethylatedβ-cyclodextrin (βPCD) in aqueous solution at pH 7.00 at 298.2 K, has been studied by UV-visible and19F NMR spectroscopy. The formation of 1∶1 and 1∶2 γCD inclusion complexes proceeds through the two equilibria: (K1) $${\text{DF + }}\gamma {\text{CD}} \rightleftharpoons {\text{DF}} \cdot \gamma {\text{CD}}$$ (K2) $${\text{DF}} \cdot \gamma {\text{CD + }}\gamma {\text{CD }} \rightleftharpoons {\text{ DF}} \cdot {\text{(}}\gamma {\text{CD)}}_{\text{2}} {\text{ }}$$ characterised byK 1=(5.5±0.2)×104 dm3 mol−1 andK 2=(2.3±0.2)×104 dm3 mol−1 derived from UV-visible spectrophotometric data. The analogous βPCD complexes are characterised byK 1=(6.86±0.02)×104 dm3 mol−1 andK 2=(8.75±2.7)×101 dm3 mol−1. The variation of the19F chemical shift of DF on inclusion is consistent with the formation of 1∶1 and 1∶2 complexes also. Comparisons with related systems are made.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00663051
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