Directed assembly of a high surface area 2D metal–organic framework displaying the augmented “kagomé dual” (kgd-a) layered topology with high H2 and CO2 uptake
The rigid and highly aromatic hexatopic, carboxylate-based organic linker H6L, under solvothermal reaction conditions with CoCl2·6H2O, directs the assembly of two new 2D MOFs (denoted as 1 and 2) with the rare kgd-a layered topology, as revealed by single crystal X-ray diffraction measurements. A unique 3-connected dinuclear cluster, Co2(–COO)3Cl, was observed in 1 and this MOF was found to be stable upon solvent removal, in contrast to 2, where single Co2+ cations serve as 3-c nodes and the structure collapses upon activation. A detailed Ar sorption measurement at 87 K revealed that 1 has an apparent BET surface area of 1299 m2 g−1 with narrow pore size distribution, centered at 6.9 Å. A very high H2 and CO2 uptake is observed reaching 209.9 cm3 (STP) g−1 and 106.8 cm3 (STP) g−1 at 77 K/1 bar and 273 K/1 bar, respectively, which is attributed to the combination of small pore size and the high density of aromatic rings in 1.