Reversible Dynamic Structural Transformation between 3D and 1D Cd–Co Heterometallic MOFs Showing Switchable Spin-Canted Antiferromagnetism

Two Cd-Co heterometallic frameworks based on the ligand methylenesuccinate acid (H2MSA), three-dimensional (3D) [CdCo6(MSA)6(μ3-OH)2(H2O)2]·H2O (1) and one-dimensional (1D) [CdCo(MSA)2(H2O)5]·3H2O (2), were synthesized at 120 °C and room temperature, respectively. Complex 1 has a 3D structure composed of an octahedral [CdO6] node and a 2D [Co6] layer unit featuring a coedge hexagonal metal skeleton, and 2 displays a 1D chain structure with Cd2+ and Co2+ ions bridged by the MSA2– ligands. The 3D and 1D structures could transform into each other reversibly in the mother solution by controlling the temperature at room temperature and 120 °C, respectively. This phenomenon was analyzed in detail and could be well explained dynamically. Magnetic studies suggest the reversible transformation between 1 and 2 is along with switchable “on–off” spin-canted antiferromagnetism.