Photoregulated Cuprous Active Sites in Phenylazoindole-Incorporated MOFs for Tunable Gas Adsorption

Photoswitchable adsorbents have garnered widespread interest because of their tunable behavior when exposed to light. Modulation strategies are primarily achieved through weak interactions, based on steric hindrance, such as alterations in pore size or the creation of gated pores, while relatively few focus on the direct regulation of stronger adsorptive interactions. Here, we report the incorporation of heteroaryl azobenzene to construct photoresponsive adsorbents, enabling the modulation of strong adsorptive interactions. As a proof of concept, phenylazoindole (PAI) was introduced as a photoresponsive motif into MOF followed by the addition of Cu I as the π-complexing active sites, yielding Cu I -incorporated U67-PAI. The isomerization of PAI alters the surface electrostatic potential surrounding Cu I from −0.24 to +0.21 eV, thereby modulating the adsorptive interactions. Upon irradiation, Cu I /U67-PAI exhibited an up to 40% change in CO uptake. This work expands the design toolbox for light-responsive adsorbents with controllable adsorptive interactions.