Guest binding drives reversible atropisomerism in cavitand hosts
Thanh V Nguyen1, David J Sinclair, Anthony C Willis
1Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|May 14, 2009
Summary
The guest-love-ometer reveals how solvent affects the structure of ortho-substituted phenyl cavitands. This competition for the cavity allows for sensitive measurement of guest binding affinities.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
Background:
- Ortho-substituted phenyl cavitands exhibit atropisomerism, leading to distinct inside-outside isomers.
- The ratio of these isomers can be influenced by external factors.
Purpose of the Study:
- To investigate the influence of solvent on the atropisomeric equilibrium of ortho-substituted phenyl cavitands.
- To develop a sensitive method for measuring relative guest binding affinities using these cavitands.
Main Methods:
- Synthesis and characterization of ortho-substituted phenyl cavitands.
- Spectroscopic analysis (e.g., NMR) to determine atropisomeric ratios in various solvents.
- Competition experiments to assess guest binding.
Main Results:
- The inside-outside atropisomeric ratio of the cavitands is highly dependent on the solvent polarity and type.
- A clear correlation was observed between solvent properties and the equilibrium ratio.
- The system demonstrated sensitivity to the presence of competing guests, indicating measurable binding affinities.
Conclusions:
- Solvent plays a crucial role in modulating the conformational preferences of ortho-substituted phenyl cavitands.
- The observed solvent dependence creates a "guest-love-ometer" for quantifying relative guest binding.
- This work provides a novel approach for probing host-guest interactions in supramolecular chemistry.
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