Lattice Expansion and Contraction in Metal-Organic Frameworks by Sequential Linker Reinstallation

Isoreticular expansion of metal-organic frameworks (MOFs) by linker elongation often leads to interpenetration or other undesired structures. Here we report a sequential linker labilization and reinstallation method to expand the unit cell dimensions of MOFs while manipulating the framework structure and interpenetration. A stable Zr-based MOF was initially synthesized as a template. Subsequently, labile linkers with imine bonds were post-synthetically introduced into the structure to destabilize the Zr-MOF. Eventually, gradual dissociation of the imine-based linkers and reinstallation of longer linkers into the defective spaces lead to the formation of non-interpenetrated isoreticular Zr-MOFs with progressively increased pore sizes. Similarly, lattice contraction can also be realized by incorporating shorter linkers. In addition to providing a powerful tool that yields control over the structures and functions of MOFs, this work also highlights new opportunities by combining the dynamic covalent chemistry with coordination chemistry in MOFs.