A metal-organic cage with light-switchable motifs for controllable CO₂ adsorption

Light-switchable composites have great potential to enable processes that can be controlled on demand, which is difficult to achieve with conventional materials that have stationary structures and properties. Here, we present a light-switchable metal-organic cage, NUT-102, structurally incorporated with pendant azobenzene groups for controllable CO₂ capture. Upon visible light irradiation, the trans isomerization of the azobenzene groups exposes the pores of NUT-102 and favors CO₂ adsorption. Conversely, upon ultraviolet light irradiation, the azobenzene groups undergo a conformation transformation from trans to cis isomerization, resulting in the sheltering of the pores and subsequently reducing CO₂ adsorption. Significantly, the light-switchable modulated CO₂ adsorption change amount can reach up to 65.2%. Moreover, density functional theory calculations further confirmed the controllable CO₂ adsorption behavior in NUT-102. The present study provides new insights into the development of novel light-switchable adsorbents tailored for controllable CO₂ adsorption.