Yang, C.-T.; Kshiragar, A.R; Charaf Eddin, A.; Lin, L.-C.*; Poloni, R.* Tuning Gas Adsorption by Metal Node-Blocking in Photoresponsive Metal-Organic Frameworks, Chem. Eur. J., just accepted, 2018

Abstract

By combining first‐principles calculations and classical molecular simulations, we provide the atomistic‐level understanding towards the notable change in CO2 adsorption upon light treatment in two recently reported photoactive metal‐organic frameworks, PCN‐123 and Cu2(AzoBPDC)2(AzoBiPyB). We demonstrate that the reversible decrease in gas adsorption upon isomerization can be primarily attributed to the blocking of the strong adsorbing sites at the metal nodes by azobenzene molecules in cis configuration. The same mechanism is found to apply also to other molecules, e.g., alkanes and toxic gases. Such understandings are instrumental to the future design of photoresponsive metal‐organic frameworks. For example, the metal node‐blocking mechanism can be leveraged to achieve optimal adsorption properties as a function of metal substitution and/or ligand functionalization; as a proof of concept, we show that the working capacity can be increased by a factor of two in PCN‐123 by replacing the Zn4O node with the more strongly adsorbing Mg4O.