Full-Dimensional Differentiation and Pathway-Wide Transformation in a Homologous Covalent Organic Framework Family

Precise dimensional control in covalent organic frameworks (COFs) represents fundamental interest in reticular chemistry, but the construction and transformation of homologous structures across the full-dimensional scale (one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D)) remain an unmet challenge. Herein, we for the first time demonstrated the construction of three highly crystalline homologous COFs with unprecedented full-dimensional differentiation and pathway-wide transformation. These facts were achieved through carefully selecting the combination of molecular building blocks with the ability to access the full-dimensional topologies, as well as navigating to distinct trapped states by regulating the synthetic protocols. Further transformation experiments and theoretical calculations elucidated the relative potential energy landscape of the homologous COF family with the dimensional energy gradient of 2D > 1D > 3D and thereby realized all thermodynamically permissible transformation pathways. Impressively, 2D-to-1D transformation involved the cleavage of bridging units and reassembly, while 2D-to-3D and 1D-to-3D transformations both underwent extensive bond breakage and repolymerization. Moreover, benefiting from efficient triplet exciton formation and minimized energy loss due to its 1D structure, the 1D COF exhibited the longest exciton lifetime and the most efficient photocatalytic uranium reduction capability among the full-dimensional homologous COFs. This work not only presents a landmark demonstration of the first-ever construction of full-dimensional homologous COFs and their interdimensional transformations but also provides strategic insights for the structural design of COF-based high-performance photocatalysts.