Tuning the Trade‐Off between Ethane/Ethylene Selectivity and Adsorption Capacity within Isoreticular Microporous Metal−Organic Frameworks by Linker Fine‐Fluorination

The pore dimension and surface property directly dictate the transport of guests, endowing diverse gas selective adsorptions to porous materials. It is highly relevant to construct metal−organic frameworks (MOFs) with designable functional groups that can achieve feasible pore regulation to improve their separation performances. However, the role of functionalization in different positions or degrees within framework on the separation of light hydrocarbon has rarely been emphasized. In this context, four isoreticular MOFs (TKL‐104−107) bearing dissimilar fluorination are rationally screened out and afforded intriguing differences in the adsorption behavior of C2H6 and C2H4. Ortho‐fluoridation of carboxyl allows TKL‐105−107 to exhibit enhanced structural stabilities, impressive C2H6 adsorption capacities (>125 cm3 g−1) and desirable inverse selectivities (C2H6 over C2H4). The more modified ortho‐fluorine group and meta‐fluorine group of carboxyl have improved the C2H6/C2H4 selectivity and adsorption capacity, respectively, and the C2H6/C2H4 separation potential can be well optimized via linker fine‐fluorination. Meanwhile, dynamic breakthrough experiments proved that TKL‐105−107 can be used as highly efficient C2H6‐selective adsorbents for C2H4 purification. This work highlights that the purposeful functionalization of pore surfaces facilitates the assembly of highly efficient MOF adsorbents for specific gas separation. The C2H6/C2H4 separation potential is successfully optimized by virtue of linker fine‐fluorination within an isoreticular cadmium‐organic framework platform. Due to the integrated balance between adsorption selectivity and capacity, fluorinated TKL‐105−107 exhibit distinct one‐step ethylene purification capabilities from C2H6/C2H4 mixtures, shedding light on the effect of tailor‐made fluorine functionalization on the advanced separation/purification applications.