Photochemically Crushable and Regenerative Metal-Organic Framework

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