Topological derivative strategy for large-pore three-dimensional covalent organic frameworks

The pursuit of three-dimensional covalent organic frameworks (3D COFs) with ultra-large pores faces fundamental challenges from structural interpenetration. We address this limitation through a topology-driven design strategy that transforms edge-transitive scu nets into two distinct derivative frameworks - mmm and jcg - via symmetry-controlled monomer selection. This approach yields contrasting pore evolution behaviors: while mmm-series COFs (JUC-693 to JUC-695) show unpredictable pore size fluctuations (2.77 nm → 4.04 nm → 1.35 nm) due to complex interpenetration patterns, jcg-series frameworks (JUC-696 to JUC-698) exhibit controlled expansion up to a record 5.24 nm pore diameter in JUC-698. Comprehensive characterization, including macromolecular encapsulation studies with vitamin B12 and myoglobin, confirms the structural integrity and accessibility of these engineered pores. Our findings establish topology-directed design as a powerful tool for overcoming interpenetration barriers in porous materials development.