Covalent organic frameworks (COFs) have attracted extensive interest due to their unique structures and various applications. However, structural diversities are still limited, which greatly restricts the development of COF materials. Herein, we report two unusual cubic (8-connected) building units and their derived 3D imine-linked COFs with bcu nets, JUC-588 and JUC-589. Owing to these unique building blocks with different sizes, the obtained COFs can be tuned to be microporous or mesoporous structures with high surface areas (2728 m2 g-1 for JUC-588 and 2482 m2 g-1 for JUC-589) and promising thermal and chemical stabilities. Furthermore, the high selectivity of CO2/N2 and CO2/CH4, excellent H2 uptakes, and efficient dye adsorption are observed. This research thus provides a general strategy for constructing stable 3D COF architectures with adjustable pores via improving the valency of rigid building blocks.
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