Metal‐Organic Frameworks with Target‐Specific Active Sites Switched by Photoresponsive Motifs: Efficient Adsorbents for Tailorable CO2 Capture

Photoresponsive metal‐organic frameworks (PMOFs) are of great interest for tailorable CO2 adsorption. However, the modulation of CO2 adsorption on reported PMOFs is based on steric hindrance or structural change due to weak interactions between CO2 and active sites. Moreover, it is a pronounced challenge to fabricate PMOFs with strong but tailorable sites for CO2 adsorption. Here, we report for the first time the construction of PMOFs with target‐specific (strong) active sites by introducing tetraethylenepentamine (TEPA) into azobenzene‐functionalized MOFs for tailorable CO2 adsorption. Amines are specific active sites for CO2, contributing to capture CO2 selectively from mixtures. DFT calculations suggest that cis/trans isomerization of azobenzene motifs trigged by UV/Vis light irradiation adjusts the electrostatic potential of amines significantly; this leads to exposure/shelter of amines and successful modulation of CO2 adsorption on strong active sites. The present PMOFs with target‐specific active sites enables us to design energy‐efficient adsorption processes for selective CO2 capture from mixtures, which is impossible to realize by traditional PMOFs.

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