pH Dependent Equilibria of Poly(anilineboronic acid)-Saccharide Complexation in Thin Films
| Autor: | Bhavana A. Deore, Michael S. Freund, Monica D. Braun |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
chemistry.chemical_classification
Conductive polymer Steric effects Polymers and Plastics Organic Chemistry Inorganic chemistry chemistry.chemical_element Polymer Condensed Matter Physics Binding constant chemistry Aldose Polymer chemistry Materials Chemistry Organic chemistry A value Physical and Theoretical Chemistry Absorption (chemistry) Boron |
| Zdroj: | Macromolecular Chemistry and Physics. 207:660-664 |
| ISSN: | 1521-3935 1022-1352 |
| DOI: | 10.1002/macp.200500560 |
| Popis: | The complexation of saccharides with poly(anilineboronic acid) as a function of pH has been studied with simultaneous measurements of open-circuit potential and mass change. This study provides an insight into this reaction as well as the relationship between complexation and open-circuit potential and the optimum pH for complexation of D-fructose and d-glucose. The optimum pH values for poly)anilineboronic acid)-D-fructose and -D-glucose complexation are near the pK a values of the complex reported in homogeneous solution. At physiological pH (7.4), the apparent binding constant of D-fructose and D-glucose with poly(anilineboronic acid) is 19.2 and 0.2 M -1 , respectively. In contrast, at pH 9.0, the apparent binding constant of D-glucose with poly(anilineboronic acid) is 12 M -1 , double than that of D-fructose. The decrease in complexation in the polymer films at pH values above the pK a of the complexes is in contrast to the behavior in homogeneous solutions. This trend is observed for both D-fructose and D-glucose using open-circuit potential, mass change and polarization modulated infrared reflection absorption spectroscopic measurements. Also, the complexation is limited in the polymer film, i.e., ≤23% boron is involved. These results suggest that steric and/or electrostatic interactions may play an important role in complexation within polymer films. |
| Databáze: | OpenAIRE |
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