Heterometallic‐Organic Cages with Customized Cavities: Constructed by Bottom‐Up Step‐Wise Coordination‐Driven Self‐Assembly

Accurately synthesizing coordination‐driven metal‐organic cages with customized shape and cavity remains a great challenge for chemists. In this work, a bottom‐up step‐wise coordination‐driven self‐assembly approach was put forward. Employing this strategy, three terpyridyl heterometallic‐organic truncated tetrahedral cages with different sizes and cavity were precisely synthesized. Firstly, the coordination of tripodal organic ligands with Ru2+ afforded dendritic metal‐organic ligands L1‐L3. Then the Ru building blocks complexed with Fe2+ and shrunk to form the desired heterometallic‐organic cages (C1‐C3). These discrete heterometallic‐organic supramolecular cages were fully characterized and displayed the large and open cavities varied from 7205 Å3 to 9384 Å3. Notably, these cages could not be directly constructed by single‐step assembly process using initial organic ligands or dimeric metal‐organic ligands, indicative of the irreplaceability of a bottom‐up step‐wise assembly strategy for size‐customized architectures. This work paves a new way for precisely constructing metal‐organic cages with well‐defined cavities. Three heterometallic‐organic cages with customized size and cavity have been precisely constructed using bottom‐up step‐wise coordination‐driven self‐assembly strategy. First, three Ru2+‐connected dendritic ligands were synthesized from initial tripodal building blocks. Then, further self‐assembly of metal‐organic ligands with Fe2+ quantitatively generate the desired tetrahedral cages, respectively.