Sequential Linker Installation: Precise Placement of Functional Groups in Multivariate Metal–Organic Frameworks

A unique
strategy, sequential linker installation (SLI), has been
developed to construct multivariate MOFs with functional groups precisely
positioned. PCN-700, a Zr-MOF with eight-connected Zr6O4(OH)8(H2O)4 clusters, has
been judiciously designed; the Zr6 clusters in this MOF
are arranged in such a fashion that, by replacement of terminal OH–/H2O ligands, subsequent insertion of linear
dicarboxylate linkers is achieved. We demonstrate that linkers with
distinct lengths and functionalities can be sequentially installed
into PCN-700. Single-crystal to single-crystal transformation is realized
so that the positions of the subsequently installed linkers are pinpointed
via single-crystal X-ray diffraction analyses. This methodology provides
a powerful tool to construct multivariate MOFs with precisely positioned
functionalities in the desired proximity, which would otherwise be
difficult to achieve.