Switching between Anion-Binding Catalysis and Aminocatalysis with a Rotaxane Dual-Function Catalyst
Katarzyna Eichstaedt1, Javier Jaramillo-Garcia1, David A Leigh1
1School of Chemistry, University of Manchester , Oxford Road, Manchester M13 9PL, U.K.
Journal of the American Chemical Society
|June 20, 2017
Summary
This study reveals a switchable rotaxane catalyst that toggles between aminocatalysis and anion-binding catalysis. Its "off" state for one reaction is the "on" state for the other, controlled by macrocycle position.
Area of Science:
- Supramolecular Chemistry
- Catalysis
- Organic Chemistry
Background:
- Switchable catalysts offer tunable reactivity for complex chemical transformations.
- Rotaxane-based molecular machines provide platforms for controlled catalytic activity.
Purpose of the Study:
- To demonstrate a dual-function rotaxane catalyst with switchable aminocatalysis and anion-binding capabilities.
- To elucidate the mechanism of switching between catalytic states based on macrocycle position.
Main Methods:
- Synthesis and characterization of a switchable [2]rotaxane.
- Investigating catalytic activity in both aminocatalysis and anion-binding reactions.
- Utilizing stimuli-induced macrocycle movement to control catalytic function.
Main Results:
- The rotaxane exhibits mutually exclusive "on" and "off" states for aminocatalysis and anion-binding catalysis.
- Anion-binding catalysis involves cooperative CH-hydrogen bonding by triazolium groups to stabilize intermediates.
- Sequential activation of catalytic sites enables tandem reaction processes.
Conclusions:
- Switchable rotaxanes can be designed as sophisticated molecular catalysts with orthogonal functions.
- Control over macrocycle positioning is key to modulating catalytic activity and enabling sequential catalysis.
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