Structural Diversity, Gas Adsorption And Magnetic Properties Of Three Coordination Polymers Based On A Rigid Multicarboxylate Ligand

Three Co(ii) coordination polymers (CPs), {[Co-2(HL)(1,4-bibb)(H2O)]center dot(CH3CN)center dot(H2O)}(n) (1), {[Co-4(L)(OH)(3)(H2O)(4)]center dot(1,4-bmib)}(n) (2) and {[Co-6(L)(2)(OH)(2)(4,4-biyb)]center dot(CH3CN)center dot(H2O)}(n) (3) have been obtained based on a V-shaped rigid pentacarboxylate ligand (H5L = 3,5-di(2 ',5 '-dicarboxylphenyl)benzoic acid) and different N-donor ligands. All complexes show 3D structures and contain open carboxyl sites and "accessible metal sites" (AMSs). The gas adsorption experiments show that 1 and 3 have a high H-2 adsorption capacity at 77 K and in particular, 3 displays the selective uptake of CO2 over CH4 (14.2 for CO2/CH4 = 0.5/0.5 and 11.0 for CO2/CH4 = 0.05/0.95 under 1 bar at 298 K). Furthermore, anti-ferromagnetic interactions among Co(ii) ions are observed in 2.