Structural Modulation of TpPa‑1 Covalent Organic Framework in Flow Synthesis Guided by Green Chemistry Principles

Area of Science:

• Materials Science
• Chemical Engineering
• Green Chemistry

Background:

• Covalent organic frameworks (COFs) offer tunable properties for diverse applications.
• Scalable and sustainable synthesis of COFs remains a challenge.
• Solvent selection critically impacts COF synthesis outcomes.

Purpose of the Study:

• To develop a solvent decision-making pathway for hazardous and scalable synthesis of TpPa-1 COF.
• To optimize COF synthesis using environmental compatibility, processability, and thermodynamic parameters.
• To implement continuous-flow synthesis for improved COF production.

Main Methods:

• Utilized the CHEM21 framework for environmental compatibility assessment.
• Applied Hansen solubility parameters for solvent processability evaluation.
• Calculated free energy of solvation for thermodynamic suitability analysis.
• Investigated solvent effects on TpPa-1 COF crystallite growth and reaction reversibility.

Main Results:

• Solvents with moderate solvation (1,4-dioxane, propylene carbonate, diacetin) were identified as optimal.
• Diacetin was determined to be the ideal solvent for continuous-flow synthesis.
• Flow-derived TpPa-1 COF exhibited a Brunauer-Emmett-Teller surface area of 418 m² g⁻¹, a 50% increase in CO2 uptake.
• Continuous-flow synthesis achieved a 30-fold increase in space-time yield (STY) with reduced energy consumption.

Conclusions:

• A solvent-thermodynamics-guided approach enables sustainable and efficient COF synthesis.
• Continuous-flow synthesis significantly enhances COF properties and production metrics.
• The developed framework provides a transparent method for optimizing COF synthesis.