Photochemically Crushable and Regenerative Metal–Organic Framework

A photochemically crushable and regenerative metal–organic framework (^DTEMOF) was developed by complexation of photochromic ligand ^PyDTE_open and 5-nitroisophthalate (nip^2–) with Cd²⁺ in DMF/MeOH. ^DTEMOF ([Cd­(nip)­(^PyDTE_open)­(H₂O)­(DMF)₂]_n) was obtained as colorless crystals. Its crystal structure revealed that ^DTEMOF adopts a tubular structure with interlocked coordination networks and can accommodate guest molecules in its one-dimensional pores. When ^DTEMOF suspended in DMF/MeOH was exposed to UV light, its crystalline network, though thermally stable up to 260 °C, was readily crushed to afford a homogeneous blue-colored solution, via ring-closing isomerization of the constituent ^PyDTE_open ligand into ^PyDTE_closed. Upon successive exposure of this solution to visible light, colorless MOF crystals identical to those of ^DTEMOF were regenerated. Light-responsive ^DTEMOF enabled highly efficient on-demand guest release.