Binding of substituted acetic acids to alpha-cyclodextrin in aqueous solution.
Complex binding constants of 23 aliphatic acids with alpha-cyclodextrin in aqueous solution were measured by potentiometry, solubility, or competitive spectrophotometry at 25 degrees C. All systems formed 1:1 acid:cyclodextrin complexes, and some of them also formed 1:2 complexes. The conjugate acids formed stronger complexes than did the conjugate bases (except for glycine). Empirical correlations of complex stabilities are shown with partition coefficients, surface areas, molar refraction, and other descriptors. Complex stability appears to result from the hydrophobic effect, the dispersion interaction, and interaction of the carboxylic acid group with the cyclodextrin.
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School of Pharmacy, University of Wisconsin, Madison 53706, USA.
Connors
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D000085:Acetates / Q000737:chemistry*; D003505:Cyclodextrins / Q000737:chemistry*; D011199:Potentiometry; D012995:Solubility; D012996:Solutions; D013053:Spectrophotometry; D047391:alpha-Cyclodextrins
D000085:Acetates; D003505:Cyclodextrins; D012996:Solutions; D047391:alpha-Cyclodextrins; C032613:alpha-cyclodextrin