Permanently porous cycloparaphenylene nanohoops via supramolecular engineering

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Nanotechnology

Background:

• Cycloparaphenylenes (carbon nanohoops) are strained macrocycles with unique optoelectronic properties and host-guest chemistry.
• They serve as molecular building blocks resembling carbon nanotubes.
• Their potential for creating porous materials is underexplored.

Purpose of the Study:

• To establish carbon nanohoops as versatile tectons for permanently porous molecular crystals.
• To synthesize and characterize novel functionalized carbon nanohoops.
• To explore the structure-property relationships in these porous materials.

Main Methods:

• Synthesis of seven new functionalized cycloparaphenylene derivatives (difluorodibenzodioxin, methoxy, catechol boron bromide).
• Structural characterization using single crystal X-ray and electron diffraction.
• Analysis of noncovalent interactions (π-π, CH-π, boron-π) stabilizing the porous structures.

Main Results:

• Successfully synthesized and characterized new functionalized carbon nanohoops.
• Achieved permanently porous molecular crystals with well-defined supramolecular architectures.
• Difluorodibenzodioxin nanohoops formed nanotubular arrays with record surface areas (up to 910 m² g⁻¹).
• Boron bromide derivatives formed 3D pore networks with enhanced CO2 binding capacity due to exposed Lewis acidic boron centers.

Conclusions:

• Carbon nanohoops are effective building blocks for creating permanently porous molecular materials.
• Functionalization allows tuning of supramolecular architecture and material properties.
• These materials demonstrate potential for applications in gas storage and separation.