Symmetrically Tetra-functionalized Pillar[6]arenes Prepared by Fragment Coupling

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Materials Science

Background:

• Partial functionalization of macrocycles is challenging due to low yields and complex purification.
• Highly symmetrical structures from one-pot syntheses hinder targeted modifications.

Purpose of the Study:

• To develop an efficient method for synthesizing symmetrically tetra-functionalized pillar[6]arenes (X-pillar[6]arenes).
• To enable versatile hetero-fragment coupling and pre-functionalization strategies for macrocycles.

Main Methods:

• A two-step fragment coupling approach was employed using pillar[6]arenes as a model system.
• Synthesis of novel macrocycles and a pillar[6]arene-based cage was achieved.

Main Results:

• Nine new macrocycles and one pillar[6]arene-based cage were successfully synthesized.
• The synthesized macrocycle, COOEtEtXP[6], displayed strong solid-state cyan luminescence under UV irradiation.
• Intramolecular through-space conjugation and supramolecular polymer formation contributed to the luminescent properties.

Conclusions:

• The developed fragment coupling method is simple, versatile, and effective for multi-functionalization of macrocycles.
• This strategy opens new avenues for designing functional macrocyclic materials, such as efficient solid-state emitters.