A Cationic MOF with High Uptake and Selectivity for CO2 due to Multiple CO2-Philic Sites

The reaction of N-rich pyrazinyl triazolyl carboxyl ligand 3-(4-carboxylbenzene)-5-(2-pyrazinyl)-1H-1,2,4-triazole (H(2)cbptz) with MnCl2 afforded 3D cationic metal-organic framework (MOF) [Mn-2(Hcbptz)(2)(Cl)(H2O)]ClDMF0.5CH(3)CN (1), which has an unusual (3,4)-connected 3,4T1 topology and 1D channels composed of cavities. MOF 1 has a very polar framework that contains exposed metal sites, uncoordinated N atoms, narrow channels, and Cl- basic sites, which lead to not only high CO2 uptake, but also remarkably selective adsorption of CO2 over N-2 and CH4 at 298-333K. The multiple CO2-philic sites were identified by grand canonical Monte Carlo simulations. Moreover, 1 shows excellent stability in natural air environment. These advantages make 1 a very promising candidate in post-combustion CO2 capture, natural-gas upgrading, and landfill gas-purification processes.