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

Two unprecedented and stable metal-organic frameworks, {[Co ₂ (H ₂ O) ₂ (L)(OH)]·2.5H ₂ O·0.5DMF} _n ( 1 ) and {[Ni ₂ (H ₂ O) ₂ (L)(OH)]·1.75H ₂ O} _n ( 2 ), have been synthesized (H ₃ L = 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 × 10 ^-5 and 1.29 × 10 ^-4 S·cm ^-1 at 363 K and 98% relative humidity (RH), respectively.
Competing Interests: The authors declare no competing financial interest.
(© 2021 The Authors. Published by American Chemical Society.)