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 C2 H6 and C2 H4 . Ortho-fluoridation of carboxyl allows TKL-105-107 to exhibit enhanced structural stabilities, impressive C2 H6 adsorption capacities (>125 cm3 g-1 ) and desirable inverse selectivities (C2 H6 over C2 H4 ). The more modified ortho-fluorine group and meta-fluorine group of carboxyl have improved the C2 H6 /C2 H4 selectivity and adsorption capacity, respectively, and the C2 H6 /C2 H4 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 C2 H6 -selective adsorbents for C2 H4 purification. This work highlights that the purposeful functionalization of pore surfaces facilitates the assembly of highly efficient MOF adsorbents for specific gas separation.

1-Methyl-3,5-bis-(3-methyl-phen-yl)benzene.

In the title compound, C(21)H(20), the dihedral angles formed by the central benzene ring with the outer benzene rings are 21.43 (6) and 31.70 (4)°. The crystal packing is stabilized by a weak π-π stacking inter-action, with a centroid-centroid distance of 3.843 (3) Å.

Bis[µ-3-(1H-benzimidazol-2-yl)benzoato]dicopper(I).

The dimeric title complex, [Cu(2)(C(14)H(9)N(2)O(2))(2)], resides on a center of symmetry. In the crystal, the mol-ecules are packed via π-π stacking inter-actions alternating between imidazole and benzene rings [mean inter-planar distances = 3.754 (3) and 3.624 (3) Å]. An inter-molecular N-H⋯O hydrogen bond links the dimers together. The two-coordinate Cu(I) atom displays an O-Cu-N bond angle of 176.3 (2)°. The Cu⋯Cu distance within the dimer is 5.100 (2) Å.