Construction of two new Co(II)-organic frameworks based on diverse metal clusters: Highly selective C2H2 and CO2 capture and magnetic properties

Abstract Two new Co(II)-complexes, namely, [(NH2Me2)2][Co4(L)2(μ2-O)2(H2O)5DMF]·2DMF·3H2O (1), [(NH2Me2)5][Co12(L)6(μ3-O)4(HCOO)(H2O)6]·2DMF·8H2O (2) were solvothermally constructed based on a rigid pyridine polycarboxylate ligand (H4L, 2,6-di(2′,5′-dicarboxyphenyl) pyridine). Complex 1 and 2 dislay 3D frameworks with various metal cluster. Complex 1 is a 3D porous framework with a (4,8)-connected topology featured by 1D pore structure in a-axis direction with binuclear cluster [Co2(COO)4O] and tetranuclear cluster [Co4(COO)8O2]. Complex 2 possess trinuclear cluster [Co3(COO)6O] and binuclear cluster [Co2(COO)5O], and it can be clearly observed that 2 is assembled by numbers of nano-cages by twisting a certain angle. Notably, the gas sorption behaviour investigation indicates that the desolvated 1a displays uptake capacity and adsorption selectivity to C2H2 and CO2 over CH4. Furthermore, the results of magnetic studies show that complex 2 exhibits antiferromagnetic interactions between Co2+ ions.