Assembly of Two Metal-Organic Frameworks Based on Distinct Cobalt Dimeric Building Blocks Induced by Ligand Modification: Gas Adsorption and Magnetic Properties.

Solvothermal reaction of 3,5-di(pyridin-4-yl) benzoic acid (HDPB) with Co(II) leads to a novel metal-organic framework, [CoO(DPB)(DMF)]· xS (1), which represents a rare reo-type net with trigonal prismatic cobalt dimer, [CoO(CO)N], as building blocks to construct a 3D framework containing three different types of nanoscale ML and ML polyhedron cages. More interestingly, under the same condition, the assembly of 4-methyl-3,5-di(pyridin-4-yl) benzoic acid (HMDPB) with Co(II) facilitates the formation of a cationic framework, [Co(MDPB)(DMF)](NO)· xS (2), with cobalt dimer, [Co(CO)N], as building blocks. Complex 2 represents the first example of a zeolite-like network with 48-nuclear SOD cage. The significant effect of subtle modification of ligand on the overall MOFs is discussed. Moreover, the gas adsorption studies reveal that 1 exhibits permanent porosity and selective CO uptake. Variable-temperature magnetic susceptibility measurements show that both 1 and 2 exhibit antiferromagnetic behavior.