A new Co(ii) metal–organic framework with enhanced CO2 adsorption and separation performance

Abstract

The new functional ligand 5-(1H-pyrazole-4-carboxamido)isophthalic acid (H₃L) reacts with CoSO₄·7H₂O to form a new three-dimensional metal–organic framework, [Co₄(HL²⁻)₄(DMF)₂(H₂O)₂]_n·solvent (1) with a new (3,6)-connected topology. 1 exhibits one-dimensional polar channels with approximate dimensions of 6.0 × 8.0 Ų decorated with accessible functional sites. These sites contribute to enhanced CO₂ uptake (103.2 cm³ g⁻¹ at 273 K and 1 bar) and CO₂/CH₄ selectivity (7.25 for CO₂/CH₄ = 50 : 50; 8.59 for CO₂/CH₄ = 5 : 95) at 298 K and 1 bar. DFT calculations were also performed to elucidate the binding sites. These results suggest that complex 1 is an attractive candidate for CO₂ adsorption and separation.