COF-300 synthesis and colloidal stabilization with substituted benzoic acids.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Synthesis

Background:

• Colloidal covalent organic framework (COF) synthesis allows control over crystallite morphology.
• Synthesizing 3D imine-linked COF colloids is synthetically challenging compared to 2D counterparts.

Purpose of the Study:

• To report a rapid synthesis method for hydrated COF-300 colloids.
• To investigate the influence of para-substituted benzoic acid catalysts on COF-300 crystallite size.
• To explore the role of acid catalysts in imine condensation and colloid stabilization.

Main Methods:

• Utilized pair distribution function analysis for material characterization.
• Employed in situ dynamic light scattering for nucleation time assessment.
• Conducted 1H NMR studies on model compounds to understand catalyst acidity effects.

Main Results:

• Achieved rapid synthesis (15 min-5 days) of hydrated COF-300 colloids (251 nm-4.6 μm) with high crystallinity.
• Identified 4-cyano and 4-fluoro benzoic acids as optimal catalysts for large COF-300 crystallites (1-2 μm).
• Demonstrated cationic stabilization of colloids (zeta potential up to +14.35 mV) due to catalyst protonation of surface amine groups.

Conclusions:

• The study provides a foundational understanding of COF-300 colloid synthesis and surface chemistry.
• Acid catalysts play a dual role in both imine condensation and colloid stabilization.
• Insights gained can guide the design of tailored COF materials with controlled morphology.