Photochemically Crushable and Regenerative Metal-Organic Framework.

A photochemically crushable and regenerative metal-organic framework () was developed by complexation of photochromic ligand and 5-nitroisophthalate (nip) with Cd in DMF/MeOH. ([Cd(nip)()(HO)(DMF)]) was obtained as colorless crystals. Its crystal structure revealed that adopts a tubular structure with interlocked coordination networks and can accommodate guest molecules in its one-dimensional pores. When 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 ligand into . Upon successive exposure of this solution to visible light, colorless MOF crystals identical to those of were regenerated. Light-responsive enabled highly efficient on-demand guest release.