A microporous 2D cobalt-based MOF with pyridyl sites and open metal sites for selective adsorption of CO2

A new microporous 2D Co-based MOF, [Co3(C6H3NO2)2(cpna)2(DMA)2]n (1) (H2cpna = 6-(4-carboxylphenyl)nicotinic acid; DMA = N,N-dimethylacetamide), has been synthesized and structurally characterized. Complex 1 shows a 2D network with 1D channel of 6.4 × 9.3 Å2 along the a-axis. Activated 1 (1a) exhibits selective gas adsorption for CO2 as compared to other gas molecules (e.g. C2H2, CH4, CO, N2) from the experimental single-component gas-adsorption isotherm (at 273K and 298K), molecular simulation and breakthrough experiments (298K). And the adsorption selectivity (CO2/C2H2, CO2/CH4, CO2/CO, and CO2/N2) was calculated with the ideal adsorbed solution theory (IAST). Activated 1 shows 9.77 wt% (2.22 mmol/g) uptake of CO2 at 1 bar and 273 K. Furthermore, the activation of 1 exhibits high ideal selectivities in adsorption of CO2 over C2H2, CH4, CO, and N2 at 298 K (1 bar), which may be attributed to the pyridyl sites on the ligands and open metal sites on the nodes of the framework. Besides, 1a could adsorb more gas molecules due to thicker layer (10.97 Å) of 2D structure.