Different Phenomena in Magnetic/Electrical Properties of Co(II) and Ni(II) Isomorphous MOFs

Two unprecedented and stable metal-organic frameworks, {[Co-2(H2O)(2)(L)(OH)]center dot 2.5H(2)O center dot 0.5DMF}(n) (1) and {[Ni-2(H2O)(2)(L)(OH)]center dot 1.75H(2)O}(n) (2), have been synthesized (H3L = 5-(5-carboxy-pyridin-3-yloxy)-isophthalic acid, DMF = N,N-dimethylformamide). Structural analysis shows that 1 and 2 are heteronuclear isomorphous, possessing a three-dimensional (3D) (4,8)-connected flu/ fluorite topological framework formed through the interconnection of tetranuclear butterfly {M-4(COO)(6)(OH)(2)} clusters and the ligands. Although the frameworks of these two compounds are similar, their magnetic properties are different. Compound 1 exhibits an antiferromagnetic interaction in the high-temperature region, while 2 shows a weak ferromagnetic interaction in the whole-temperature region. Furthermore, considering the presence of hydroxyl groups and water molecules in the frameworks, we tested their proton conductivity. The efficient proton transfer pathway in the framework endowed 1 and 2 with excellent proton conductivities of 9.07 x 10(-5) and 1.29 x 10(-4) S center dot cm(-1) at 363 K and 98% relative humidity (RH), respectively.

Automated summary

Two unprecedented and stable metal-organic frameworks, {[Co-2(H2O)(2)(L)(OH)]center dot 2.5H(2)O center dot 0.5DMF}(n) (1) and {[Ni-2(H2O)(2)(L)(OH)]center dot 1.75H(2)O}(n) (2), were synthesized. While the structures of compounds 1 and 2 are similar, they exhibit different magnetic properties. Compound 1 shows antiferromagnetic interaction at high temperatures, while compound 2 shows weak ferromagnetic interaction across all temperature ranges. Additionally, both frameworks showed excellent proton conductivities due to the presence of hydroxyl groups and water molecules.