Reversible Dimensional Programming of Covalent Organic Frameworks

While the dimensionality of covalent organic frameworks (COFs) is a fundamental determinant of their physicochemical properties, their precise control remains a mystery and poses considerable challenges. Herein, we present a novel reversible coordination-directed clip-off chemistry strategy for reversible dimensional programming of COFs. Utilizing COFs containing coordinative Ag-N bonds as templates, structural transformation from a higher dimension to the lower one can be achieved by selectively cleaving these linkages. Noticeably, a 3D COF is converted into an unprecedented 1.5-dimensional (1.5D) COF, which is constructed with three-dimensional (3D) bonds but exhibits one-dimensional (1D) linear chains. This dimensional tailoring is fully reversible; reintroduction of Ag(I) repairs the cleaved bonds, restoring the original dimensions. Significantly, the derived lower-dimensional COFs exhibit markedly improved efficiency in extracting uranium from seawater and mining wastewater.