Cyclicurilarenes: Hybridizing Bambusurils with Macrocyclic Arenes

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Host-Guest Chemistry

Background:

• The cyclicurilarene receptor family is known for its unique structural and binding properties.
• Developing macrocycles with adaptable conformations is crucial for molecular recognition.

Purpose of the Study:

• To extend the cyclicurilarene receptor family by synthesizing novel macrocycles.
• To investigate the conformational flexibility and substrate binding capabilities of the new compounds.
• To explore the influence of stereochemistry on molecular arrangement and interactions within the macrocycles.

Main Methods:

• Synthesis of macrocycles via nucleophilic substitution between 2,4-dimethylglycoluril and bis(bromomethyl)-substituted dimethoxybenzene.
• Characterization of the synthesized cyclicurilarenes, including their anti/syn-configurations.
• Solid-state structural analysis to determine acetonitrile positions.
• Solution-state studies investigating hydrogen bonding with alanine derivatives.

Main Results:

• Successfully synthesized novel cyclicurilarenes with conformational flexibility, resembling bambusurils.
• Observed distinct acetonitrile positions in anti/syn-configured cyclicurilarenes in the solid state.
• Demonstrated intracavity hydrogen bond formation between inward-oriented glycoluril units and an alanine derivative in chloroform.
• Synthesized four- and six-membered cyclicurilarenes with alternating dimethoxybenzene and glycoluril units.

Conclusions:

• The extended cyclicurilarene family provides macrocycles with adaptable conformations for diverse substrate recognition.
• Stereochemistry of glycoluril units significantly impacts solid-state molecular packing and solution-state interactions.
• These findings contribute to the design of sophisticated host molecules for molecular encapsulation and recognition.