Theoretical studies of inclusion complexes of β-cyclodextrin with methylated benzoic acids

✍ Scribed by Ming-Ju Huang; John D. Watts; Nicholas Bodor

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 175 KB
• Volume: 64
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1997)64:6<711::aid-qua8>3.0.co;2-z

✦ Synopsis

AM1 semiempirical molecular orbital calculations have been performed Ž . on the inclusion complexes of ␤-cyclodextrin ␤-CD with methylated benzoic acids in two orientations, the ''head-first'' and ''tail-first'' positions. In the former, the CO H 2 group points toward the primary hydroxyls of the CD. In the latter, it points away from them. Out of 30 possible inclusion complexes, AM1 results predict only three clearly stable inclusion complexes. These are ␤-CD with 4-methyl benzoic acid in the head-first position, ␤-CD with 2,4-dimethyl benzoic acid in the head-first position, and ␤-CD with 3,5-dimethyl benzoic acid in the tail-first position. The orientations of the stable inclusion complexes correlate with the total number of intramolecular hydrogen bonds and intermolecular hydrogen bonds. The stability of a complex also correlates with the closeness of the host and guest geometries in the complex to their isolated molecule geometries.