Photoswitchable Metal-Organic Framework as a Smart Nanoreactor for Ultraviolet Light-Enhanced Confined Catalysis.

Confined catalysis, where a chemical reaction is accommodated within a nanoscale host, provides an effective approach to control the pathways and outcomes of catalytic transformations. However, the confinement effect is typically limited to a fixed rate and/or selectivity once the nanohost is chosen. Herein, we developed a photoresponsive metal-organic framework (MOF) as a "smart" nanohost to realize ultraviolet (UV) light-enhanced confined catalysis of Knoevenagel condensation. Photoresponsive MOF of was thus prepared by solvothermal strategy where azobenzene-4,4'-dicarboxylic acid (ADA) was used as the photoactive linker to coordinate with zinc nitrate. Characterization results suggested that UV light could decrease the pore size of due to suppressed bending of the azobenzene-containing ADA linker in . It enforced the proximity between substrates and catalytic groups within the confined space, and thus enhanced the confinement effect on Knoevenagel condensation. The UV light-enhanced confined catalysis enabled the translation of light stimulus into chemical signal, which may open up new control on the basis of the specific reaction field.