Enhanced Benzene Adsorption in Chloro-Functionalized Metal-Organic Frameworks

The functionalization of metal-organic frameworks (MOFs) to enhance the adsorption of benzene at trace levels remains a significant challenge. Here, we report the exceptional adsorption of trace benzene in a series of zirconium-based MOFs functionalized with chloro groups. Notably, MFM-68-Cl₂, constructed from an anthracene linker incorporating chloro groups, exhibits a remarkable benzene uptake of 4.62 mmol g^-1 at 298 K and 0.12 mbar, superior to benchmark materials. In situ synchrotron X-ray diffraction, Fourier transform infrared microspectroscopy, and inelastic neutron scattering, coupled with density functional theory modeling, reveal the mechanism of binding of benzene in these materials. Overall, the excellent adsorption performance is promoted by an unprecedented cooperation between chloro-groups, the optimized pore size, aromatic functionality, and the flexibility of the linkers in response to benzene uptake in MFM-68-Cl₂. This study represents the first example of enhanced adsorption of trace benzene promoted by -CH···Cl and Cl···π interactions in porous materials.