Induced-fit molecular recognition with water-soluble cavitands

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry

Background:

• Cavitands are macrocyclic hosts with tunable cavities.
• Water-soluble hosts are valuable for biological and environmental applications.
• Controlling guest binding and exchange is crucial for host-guest chemistry.

Purpose of the Study:

• To synthesize novel water-soluble cavitands (1 and 2).
• To investigate their complexation with lipophilic guests (caviplexes).
• To characterize the binding kinetics and thermodynamics.

Main Methods:

• Synthesis of novel water-soluble cavitands.
• Spectroscopic analysis (NMR) to study complex formation and guest exchange.
• Determination of association constants (Ka) in aqueous and methanolic solutions.

Main Results:

• Water solubility achieved through ammonium and amide groups.
• D2d velcraplex dimers observed in solution, with conformational changes upon guest addition.
• Slow guest exchange rates (NMR time-scale) and determined association constants.
• Direct observation and stoichiometry of caviplexes confirmed.

Conclusions:

• Novel water-soluble cavitands with significant binding affinities were developed.
• The synthesized cavitands exhibit slow guest exchange, indicating stable complex formation.
• These cavitands show promise for applications requiring selective molecular recognition and encapsulation.