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Updated: Jul 19, 2026
06:35
Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
The influence of macrocyclic polyether constitution upon ammonium ion/crown ether recognition processes
1Department of Chemistry and Biochemistry, University of California, Los Angeles 90095-1569, USA.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|August 5, 2000
Summary
Modified crown ethers show selective binding of secondary dialkylammonium ions. Benzometaphenylene[25]crown-8 forms rotaxanes, while bismetaphenylene[26]crown-8 does not bind these ions, demonstrating structure-activity relationships.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
Background:
- Dibenzo[24]crown-8 (DB24C8) readily binds secondary dialkylammonium (R2NH2+) ions forming [2]pseudo-rotaxanes.
- Investigating structural modifications of DB24C8 is crucial for understanding ion-binding selectivity.
Purpose of the Study:
- To explore the impact of replacing catechol rings with resorcinol rings in DB24C8 on R2NH2+ ion binding.
- To synthesize and characterize novel crown ether-based rotaxanes.
Main Methods:
- Synthesis of benzometaphenylene[25]crown-8 (BMP25C8) and bismetaphenylene[26]crown-8 (BMP26CS).
- Co-crystallization studies and X-ray crystallography to determine structures.
- Solution-state binding studies and NMR spectroscopy (1H, 13C, T-ROESY) for characterization.
- Rotaxane synthesis via amine-isocyanate reaction.
Main Results:
- BMP25C8 forms [2]pseudorotaxanes in the solid state and binds R2NH2+ ions in solution, enabling the synthesis of the first BMP25C8-containing [2]rotaxane.
- Characterization of both [2]rotaxanes by NMR and X-ray crystallography revealed diastereotopic protons due to unsymmetrical components.
- BMP26CS, with both catechol rings replaced by resorcinol, showed no significant binding of R2NH2+ ions in solution or solid states.
Conclusions:
- Partial replacement of catechol with resorcinol in DB24C8 (forming BMP25C8) retains and enables rotaxane formation with secondary dialkylammonium ions.
- Complete replacement (forming BMP26CS) abolishes ion binding, highlighting the importance of specific structural features for supramolecular complexation.
- NMR spectroscopy, particularly T-ROESY, is effective in assigning diastereotopic protons and confirming complex structures.
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