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Heterodimerization of dye-modified cyclodextrins with native cyclodextrins
Tetsuo Kuwabara1, Taiyo Aoyagi, Makoto Takamura
1Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Yamanashi University, 4-3-11 Takeda, Kofu 400-8511, Japan. kuwabara@ab11.yamanashi.ac.jp
The Journal of Organic Chemistry
|February 22, 2002
Summary
Dye-modified cyclodextrins (CDs) form heterodimers with native CDs, creating new cavities for molecular assembly. These complexes show varied association behaviors based on dye structure and substituents, enabling the construction of ordered supramolecular structures.
Area of Science:
- Supramolecular Chemistry
- Host-Guest Chemistry
- Materials Science
Background:
- Cyclodextrins (CDs) are cyclic oligosaccharides with hydrophobic cavities capable of host-guest complexation.
- Dye-modified cyclodextrins offer potential for creating functional supramolecular assemblies.
- Understanding heterodimerization between different cyclodextrins is crucial for designing advanced materials.
Purpose of the Study:
- To investigate the heterodimerization behavior of various dye-modified beta-cyclodextrins (CDs) with native cyclodextrins (alpha-CD and beta-CD).
- To elucidate how structural variations in dye-modified CDs influence their association constants and complexation modes.
- To explore the potential of these heterodimers for constructing ordered molecular arrays and supramolecular heteropolymers.
Main Methods:
- Absorption spectroscopy
- Induced circular dichroism (ICD) spectroscopy
- Investigation in aqueous solutions across different pH values
Main Results:
- Azo dye-modified beta-CDs (1-3) exhibited distinct association behaviors with native CDs, influenced by dye substituent position and electronic character.
- p-Methyl red-modified beta-CD (1) formed intramolecular self-complexes and heterodimers with alpha-CD, showing significant association constants.
- Phenolphthalein-modified beta-CD (4) and p-nitrophenol-modified beta-CDs (5, 6) also demonstrated varying degrees of heterodimerization with native CDs, with structural features impacting binding affinity.
Conclusions:
- Dye-modified CDs, when not tightly self-included, can associate with native CDs to form heterodimers.
- These heterodimers possess accessible cavities suitable for binding additional guest molecules.
- The findings support the construction of more ordered molecular arrays and supramolecular heteropolymers using these tunable heterodimeric systems.