Diversity-Oriented Construction and Interconversion of Multicavity Supermacrocycles for Cooperative Anion-π Binding

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Crystal Engineering

Background:

• Supermacrocycles are large cyclic molecules with potential applications in host-guest chemistry.
• Controlling the size and structure of supermacrocycles remains a synthetic challenge.

Purpose of the Study:

• To develop a versatile one-pot strategy for synthesizing diverse supermacrocycles.
• To investigate the influence of reaction conditions on supermacrocycle formation and structure.
• To explore the host-guest properties of the synthesized supermacrocycles.

Main Methods:

• A one-pot synthesis using rationally designed macrocyclic precursors.
• Systematic variation of the base (cesium fluoride, CsF) concentration.
• Structural characterization using X-ray crystallography.
• Host-guest complexation studies with organic anions.

Main Results:

• A novel one-pot strategy successfully constructed diverse supermacrocycles.
• Base concentration critically controlled supermacrocycle size and structure, yielding regular or reorganized motifs (oxacalix[2]arene[2]triazine).
• Base-mediated transformations between supermacrocycles were observed.
• Synthesized supermacrocycles with large cavities and electron-deficient triazine moieties effectively hosted organic anions (e.g., 2-carboxyacetate) via multiple anion-π interactions.
• First crystallographic evidence of sandwich-like structures driven by anion-π interactions was obtained.

Conclusions:

• The developed one-pot strategy offers a versatile route to diverse supermacrocycles.
• Reaction conditions, particularly base concentration, are key to controlling supermacrocycle architecture.
• The synthesized supermacrocycles demonstrate significant potential for anion recognition and binding through anion-π interactions.