Design and Synthesis of Box[6]arenes for 3D Charge-Transfer Co-Crystal Engineering via Macrocyclic Self-Complementary...

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Constructing 3D charge-transfer (CT) co-crystals with programmable functionality is limited by conventional assembly strategies.
• Developing novel macrocyclic hosts is crucial for overcoming dimensional constraints in crystal engineering.

Purpose of the Study:

• To introduce a new synthetic macrocycle, box[6]arene (B[6]A), with a flexible skeleton for 3D CT co-crystal formation.
• To explore the self-assembly and functional properties of B[6]A-based co-crystals with electron-deficient guests.

Main Methods:

• Synthesis and characterization of a novel flexible macrocycle, box[6]arene (B[6]A).
• Co-crystallization of B[6]A with planar electron-deficient guests (TCNB, TFTN, TClTN) via exo-wall CT interactions.
• Spectroscopic analysis to determine fluorescence properties and vapochromic behavior.

Main Results:

• B[6]A adopts two distinct conformations (B[6]Aα and B[6]Aβ), facilitating 3D macrocycle-based co-crystal (MCC) formation.
• Synthesized MCCs with TCNB, TFTN, and TClTN exhibiting tunable fluorescence at 690, 594, and 592 nm, respectively.
• Activated B[6]A-TCNB MCCs showed selective vapochromic responses to picoline isomers through a dual mechanism.

Conclusions:

• The flexible B[6]A enables the construction of well-defined 3D CT co-crystals, overcoming limitations of rigid hosts.
• These MCCs offer tunable luminescence and selective vapochromic sensing capabilities.
• This work advances the design of functional macrocyclic arenes and 3D MCCs for luminescent materials and sensing applications.