Magnetic Tuning of an Anionic Co^II-MOF through Deionization of the Framework: Spin-Canting, Spin-Flop, and Easy-Plane Magnetic Anisotropy

An anionic Co^II-MOF, (Me₂NH₂)[Co₃(Me₂NH)₃(OH)(SDBA)₃] (1) (H₂SDBA=4,4′-sulfonyldibenzoic acid) consisting of highly symmetric Co^II₃(μ₃-OH) triangles exhibits spin-canting, spin-flop, and easy-plane magnetic anisotropy. Measurement on a single crystal shows that the ab plane of 1 is the easy magnetization plane. After structural modification through simultaneous removal of the coordinated dimethylamine (DMA) molecule at the Co center and the ionic groups DMA⁺and OH⁻, the resulting neutral amorphous framework 2 displays an enhanced spin frustration effect. The deionization of 1 does not result in the collapse of the framework, showing the high stability of the backbone structure.