Rigid, biconical hydrogen-bonded dimers that strongly encapsulate cationic guests in solution and the solid state

Area of Science:

• Supramolecular Chemistry
• Organic Chemistry
• Materials Science

Background:

• Cavitands are molecular hosts with defined cavities capable of molecular recognition.
• Self-assembly is a key process in constructing complex supramolecular architectures.
• Understanding host-guest interactions is crucial for designing functional molecular systems.

Purpose of the Study:

• To investigate the self-assembly behavior of a novel tetraarylene-bridged cavitand.
• To characterize the structure and stability of the self-assembled cavitand.
• To explore the guest encapsulation properties of the cavitand dimer.

Main Methods:

• Solution-state Nuclear Magnetic Resonance (NMR) spectroscopy, including 1H NMR and Diffusion Ordered Spectroscopy (DOSY).
• Crystallography for solid-state structural analysis (implied by mention of solid state).

Main Results:

• The tetraarylene-bridged cavitand undergoes facile dimerization in solution.
• Dimerization occurs via a unique seam of interdigitated hydrogen bonds.
• The hydrogen-bonded dimer is stable in the presence of polar co-solvents.
• The cavitand cavity selectively encapsulates small cationic guests, such as tetraethylammonium.
• Neutral guest molecules are not encapsulated.
• Encapsulation of tetraethylammonium restricts its conformational flexibility in both solution and solid states.

Conclusions:

• The novel rigid cavitand exhibits robust self-assembly into hydrogen-bonded dimers.
• The cavitand dimer displays selective binding of cationic guests.
• This work provides insights into the design of self-assembling host molecules for specific guest recognition.