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A 3D Porous Cobalt−Organic Framework Exhibiting Spin-Canted Antiferromagnetism and Field-Induced Spin-Flop Transition

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journal contribution
posted on 2007-11-12, 00:00 authored by You-Gui Huang, Da-Qiang Yuan, Long Pan, Fei-Long Jiang, Ming-Yan Wu, Xu-Dong Zhang, Wei, Qiang Gao, Jeong Yong Lee, Jing Li, Mao-Chun Hong
Two 3D cobalt−organic frameworks formulated as [Co3(2,4-pydc)23-OH)2]n·5nH2O (1) and [Co3(2,4-pydc)23-OH)2(H2O)]n·7nH2O (2) (2,4-pydc = pyridine-2,4-dicarboxylate) have been hydrothermally synthesized and characterized. Both compounds 1 and 2 exhibit the 3D porous frameworks with hydroxyl-bridged metal Δ-chains. However, in comparison with only two crystallographically independent CoII ions in a unit of 2, three crystallographically independent CoII ions are found in an asymmetric unit of 1, where their Δ-chains are constructed by two types of vertexes sharing quadrangles formed via edge-sharing triangles. Magnetic studies show that 1 exhibits spin-canted antiferomagnetism and a field-induced spin-flop transition while 2 behaves as a normal antiferromagnet. The magnetic properties are largely retained by the porous frameworks of dehydrated 1 and 2 compounds. Gas adsorption measurements indicate that both the dehydrated compounds absorb H2 into their pores.