Substituent Controlled Framework Transformation Based on Solvent-Assisted Linker Exchange

The ligand exchange technique is a common method for postsynthesis isoreticular structures of metal-organic frameworks (MOFs). Here, an interesting framework transformation after linker exchange was realized by simply controlling the substituent length of organic ligands. H-1 NMR spectroscopy of the digested samples indicated full ligand exchange in bulk Cd-MOF samples. In the target Cd-MOFs, all the substituents of the ligands orient to the inside of the hexagonal open channels. With the shortening of the substituent length, the size of the open channels gradually increased, and the air-stability of the structures became poor, which led to the structural transformation of Cd-MOF. Strikingly, the Cd- MOF structure with the largest pore size could complete the structural transformation soon even though in the mother liquor.

Automated summary

By controlling the length of the substituents on organic ligands, the framework structure of metal-organic frameworks (MOFs) can be transformed, resulting in changes in pore size and structural stability.