Fabrication of type I photoresponsive porous liquids by host surface engineering

Photoresponsive porous liquids (PPLs) have garnered significant attention due to their controllable gas adsorption behavior under light. Owing to the difficulty in preparation, only some type II and III PPLs have been reported, while type I PPLs remain unexplored due to the challenge of simultaneously integrating photoresponsive units and achieving liquefaction within a single porous host. Here, we report for the first time the synthesis of a type I PPL through a surface‐engineering strategy. Azobenzene‐containing UiO‐66 (U‐Azo) is constructed from photoresponsive units (H 2 Azo) and zirconium clusters, followed by surface coating with imidazolium‐based long‐chain ligands (H 2 Deim), yielding U‐Azo@U‐Deim. The imidazolium cations enable ion exchange with macromolecular organic anions (PEGS), inducing liquefaction and thereby affording the type I PPL, PL‐Azo@Deim. The obtained PPL exhibits a 51.3% change in propane adsorption under light, significantly exceeding U‐Azo@U‐Deim (5.5%). The photoresponsivity stems from differential propane binding with cis – trans azobenzene and its effect on cavity accessibility.