Asymmetric and symmetric occupation of active sites in porous copper(II) metal-organic frameworks with their gas absorption

• Two-interpenetrated microporous compounds.
• Different stability.
• Storage and separation of gases.

Solvothermal synthesis afford two new porous metal-organic frameworks (MOFs): {[Cu6(L)3(H2O)4(py)2]·6(DMF)13(H2O)}n (1) and {[Cu6(L)3(H2O)6]·29(H2O}n (2). [5,5′-(1,3-phenylenebis(methylene))bis(oxy)diisophthalic acid (HL)]. Although possessing similar structures, the two MOFs have markedly different stabilities. Compound 1 and 2 can take up 16.8 mg/g and 15.9 mg/g of H2 at 77 K at 1 bar and 133 cm3/g and 120 cm3/g of H2 at 87 K (Fig. 8), which is higher than the performance of well-known MOFs PCN-6 and HKUST-1 at 77 K and 1 bar. Notably, both MOFs exhibited highly efficient, selective adsorption of CO2 over CH4 under ambient conditions. Such compounds may therefore prove useful for gas separation and purification.

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