Study on Inclusion Complex Formation of <Emphasis Type="Italic">m</Emphasis>-Aminobenzoic Acid with Native and Substituted <Emphasis Type="Italic">β</Emphasis>-Cyclodextrins |
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Authors: | Irina V Terekhova Natalya A Obukhova |
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Institution: | (1) Institute of Solution Chemistry of Russian Academy of Sciences, 1 Akademicheskaya str., 153045 Ivanovo, Russian Federation |
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Abstract: | The complex formation of native and substituted β-cyclodextrins with m-aminobenzoic acid in water was characterized by calorimetry, 1H NMR and UV spectroscopic studies. These studies showed that β-, hydroxypropyl-β- and methyl-β-cyclodextrins form 1:1 inclusion complexes with m-aminobenzoic acid. The thermodynamic properties of complex formation (K,Δc
G
o,Δc
H
o,Δc
S
o) were calculated. It was found that the processes of complexation are mainly favorable entropically. Introduction of hydroxypropyl-
and methyl-substituents into the β-CD molecule results in negligible enhancement of stability of the complexes formed. The structure of these substituents has
no influence on the stability constant values. The insertion of the carboxylic group of m-aminobenzoic acid into the cyclodextrin cavity was confirmed by 1H NMR data. |
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Keywords: | m-Aminobenzoic acid Cyclodextrin Inclusion complex Thermodynamics Calorimetry UV- and NMR-spectroscopy |
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