Light-Responsive Aldehyde-Reduction Catalysis Through Catalyst Encapsulation.

We report a light-responsive tetrahedral metal-organic capsule that binds a perrhenate catalyst, which is released selectively upon irradiation with 350 nm light, turning on the catalytic reduction of organic carbonyls by hydrosilanes. The catalytic activity can be switched off by heating at 75 °C for 2.5 h, which stimulates capsule reformation and catalyst re-encapsulation. Multiple on-off cycles were shown, with a clear relationship between product yield and light irradiation time. Encapsulation thus enables the coupling of light-responsiveness to catalysis in a manner that might be generalized to other catalysts and capsules.