Geometry-Induced Construction of Sub-Stoichiometric 3D Covalent Organic Frameworks for SO2 Capture

Three-dimensional covalent organic frameworks (3D COFs) have emerged as a rapidly growing class of crystalline porous materials, yet reported structures adhere to the reticular chemistry paradigm of fully connected building blocks. Here, we report a geometry-induced construction strategy that enables the synthesis of sub-stoichiometric 3D COFs─JUC-748, JUC-749, and JUC-750─by deliberately combining building blocks with similar geometries but distinct connectivity. Their structures are determined by continuous rotation electron diffraction and powder X-ray diffraction, revealing that connectivity incompatibility enforces partial condensation and leaves unreacted aldehyde groups periodically arrayed along the pore walls. The frameworks exhibit Brunauer–Emmett–Teller surface areas up to 2836 m2 g–1, and the spatially ordered aldehyde modified pores create a highly favorable adsorption environment for SO2. Remarkably, JUC-748 achieves a SO2 uptake of 16.9 mmol g–1 at 298 K and 1 bar, representing one of the highest values reported for porous organic materials to date. This work establishes geometry-induced construction as a powerful and general strategy for creating intrinsically functionalized 3D COFs with ordered reactive sites, high porosity, and excellent adsorption performance