Multistep Growth Pathway of Covalent Organic Framework Onion Nanostructures.

Area of Science:

• Materials Science
• Nanotechnology
• Supramolecular Chemistry

Background:

• The growth mechanisms of complex organic macromolecular materials in solution are not fully understood.
• Covalent Organic Frameworks (COFs) are important synthetic materials with complex structures.

Purpose of the Study:

• To elucidate the real-time growth pathways of covalent organic framework (COF) onion nanostructures.
• To understand the molecular arrangement driving the formation of these complex nanostructures.

Main Methods:

• Liquid-phase transmission electron microscopy (TEM) was used for in situ characterization.
• Real-time imaging captured the dynamic growth processes of COF nanostructures.

Main Results:

• Observed COF onion nanostructure growth involves graphitic layer formation, layer attachment, ring closure, and relaxation.
• Growth dynamics show variations in orientation and curvature, influencing order-disorder transitions and defect generation.
• Molecular arrangement was identified as a key driver in nanostructure formation.

Conclusions:

• Direct imaging of COF nanostructure growth in liquids provides critical insights into formation mechanisms.
• This research opens avenues for controlling COF crystal morphology, composition, and hierarchical structure development.