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Selective Nitrate Recognition by a Halogen-Bonding Four-Station [3]Rotaxane Molecular Shuttle
Timothy A Barendt1, Andrew Docker1, Igor Marques2
1Chemistry Research Laboratory, Department of Chemistry, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
Angewandte Chemie (International Ed. in English)
|July 21, 2016
Summary
This study reports the first halogen bonding rotaxane, a novel interlocked molecule. It selectively binds nitrate anions through a unique dynamic pincer mechanism, demonstrating advanced anion recognition capabilities.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Chemical Sensing
Background:
- Rotaxanes are mechanically interlocked molecules with potential applications in molecular machines and sensors.
- Halogen bonding is an increasingly important non-covalent interaction for molecular recognition.
- Developing selective anion receptors remains a significant challenge in supramolecular chemistry.
Purpose of the Study:
- To synthesize and characterize the first halogen bonding [3]rotaxane host system.
- To investigate the anion binding selectivity and mechanism of the synthesized rotaxane.
- To compare the recognition properties with a hydrogen bonding analogue.
Main Methods:
- Synthesis of a novel [3]rotaxane with a bis-iodo triazolium-bis-naphthalene diimide axle.
- Proton Nuclear Magnetic Resonance (1H NMR) anion binding titration experiments.
- Molecular dynamics (MD) simulations to elucidate binding mechanisms.
Main Results:
- The synthesized halogen bonding rotaxane selectively binds nitrate anions over other common oxoanions and chloride.
- Anion binding is mediated by a novel dynamic pincer mechanism involving macrocycle shuttling.
- The rotaxane forms a 1:1 stoichiometric sandwich complex with the nitrate anion.
- Enhanced anion recognition was observed compared to a hydrogen bonding analogue.
Conclusions:
- The first halogen bonding [3]rotaxane has been successfully synthesized and characterized.
- This rotaxane exhibits high selectivity for nitrate anions via a unique dynamic pincer mechanism.
- The findings open new avenues for designing advanced interlocked receptors for specific anion recognition.
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