Two 2D microporous MOFs based on bent carboxylates and a linear spacer for selective CO2 adsorption

Two new 2D MOFs, formulated as {[Cd(OBA)(L)]center dot DMF}(n), 1 and {[Zn-2(SDB)(2)(L)]center dot EtOH center dot 3H(2)O center dot 2DMF}(n), 2 (L = 3-pyridinecarboxaldehyde nicotinoylhydrazone, H(2)OBA = 4,4'-oxybis(benzoic acid), H2SDB = 4,4'-sulfonyldibenzoic acid, DMF = N,N-dimethylformamide), have been synthesized at room temperature and characterized by elemental analyses (EA), FTIR spectra, single-crystal X-ray diffraction analyses (SCXRD), powder X-ray diffraction analyses (PXRD) and thermogravimetric analyses (TGA). The structural investigations reveal that both MOFs can be rationalized as a 4-c, uninodal net with sql topology. 1 and 2 are permanently microporous, having 1D channels with approximate sizes of 3.6 x 4.2 angstrom(2) and 6.6 x 8.0 angstrom(2), respectively. Furthermore, CO2, CH4 and N-2 sorption studies are carried out in detail at varying temperatures, and the results show that the adsorption capacities of both 1 and 2 towards CO2 are higher than those towards CH4 and N-2. Importantly, IAST calculations reveal that 1 and 2 display high separation selectivities for CO2/N-2 (15:85) and CO2/CH4 (50: 50) mixtures at ambient conditions.