Phosphine‐Catalytic Synthesis of Covalent Organic Frameworks: Accessing Structural Crystallinity and Applicable Processability

Abstract An unprecedented synthetic strategy is reported for crystalline covalent organic frameworks (COFs) through the catalysis of phosphine derivatives. Different from most COF syntheses requiring acid‐ or base‐catalytic conditions, two distinct mechanisms involving zwitterionic and hydrogen‐bonded intermediates are demonstrated when using triphenylphosphine and triphenylphosphine oxide/sulfide as catalysts, respectively. They are capable of catalyzing the reaction in different conditions, including solid‐melting, suspension, and solution states, to afford highly crystalline COFs in tunable forms of monoliths, powders, and gels. Such a phosphine‐catalytic strategy is versatile for synthesizing COFs featuring various linkage chemistries, including imine, β‐ketoenamine, and hydrazone, and diverse structural topologies and pore shapes. This work provides novel catalysts for COF synthesis and expands the aspect of phosphine‐based organocatalysis.