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Protons as the triggers to regulate hydrogen-bonding receptors
Mohammad H Al-Sayah1, Neil R Branda
1Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2.
Organic Letters
|March 15, 2002
Summary
Protonating alkylamines in new receptors forms intramolecular host-guest complexes. These complexes alter receptor shapes, hindering their ability to bind uracil and carboxylate guests.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
Background:
- Receptor design is crucial for molecular recognition.
- Crown ethers are known for cation binding.
- Alkylamine protonation can introduce positive charges for host-guest interactions.
Purpose of the Study:
- To investigate host-guest complexation in novel receptors.
- To understand the effect of alkylamine protonation on receptor conformation.
- To evaluate the impact of these interactions on guest binding.
Main Methods:
- Synthesis of two novel receptors containing crown ether macrocycles.
- Protonation of alkylamine moieties within the receptors.
- Spectroscopic and structural analysis to study conformational changes.
- Competitive binding studies with uracil and carboxylate guests.
Main Results:
- Protonation of alkylamines led to intramolecular host-guest associations with crown ether units.
- These associations induced significant conformational changes in the receptor structures.
- The conformational changes precluded the receptors from acting as effective hydrogen bond donors for uracil and carboxylate guests.
Conclusions:
- Intramolecular host-guest complexation can effectively modulate receptor conformation.
- This modulation can be used to control or inhibit the binding of specific guest molecules.
- The studied receptors demonstrate a mechanism for allosteric guest recognition.