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Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
Strong, size-selective, and electronically tunable C-H...halide binding with steric control over aggregation from
1Chemistry Department, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, USA.
Journal of the American Chemical Society
|August 15, 2008
Summary
Shape-persistent triazolophanes selectively bind chloride and bromide anions due to their fixed cavity size. Substituent modifications tune binding strength and aggregation, highlighting the importance of receptor design for anion recognition.
Area of Science:
- Supramolecular Chemistry
- Host-Guest Chemistry
- Organic Synthesis
Background:
- Anion recognition is crucial in biological and chemical processes.
- Developing selective synthetic receptors for anions remains a significant challenge.
- Hydrogen bonding interactions are key to receptor-anion binding.
Purpose of the Study:
- To synthesize novel shape-persistent [3(4)]triazolophanes.
- To investigate the anion binding affinities and selectivity of these receptors.
- To understand the role of structural features and substituents in modulating binding strength and aggregation.
Main Methods:
- Modular synthesis of [3(4)]triazolophanes with varying substituents (t-butyl, OTg).
- UV titrations to determine halide anion binding affinities.
- Diffusion NMR experiments to study aggregation behavior.
- Comparison with a foldamer analogue to assess preorganization effects.
Main Results:
- [3(4)]Triazolophanes exhibit selective binding for Cl(-) and Br(-) anions (Ka > 1,000,000 M(-1)).
- Binding affinity is tunable by modifying phenylene linker substituents, impacting electron-donating character.
- Preorganization significantly enhances binding affinity compared to a foldamer analogue.
- Increased aggregation was observed with electron-donating OTg substituents.
Conclusions:
- The fixed cavity size of [3(4)]triazolophanes is critical for selective anion recognition.
- Phenylene linker substituents play a dual role in tuning binding strength and controlling aggregation.
- These findings provide insights into designing advanced anion receptors for specific applications.
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