Switching a 2D Co(II) Layer to a 3D Co7-Cluster-Based Metal-Organic Framework: Syntheses, Crystal Structures, and Magnetic Properties

Two 2D layered coordination networks with formulas of {[Co(TPA)Cl](H2O)(2.5)}(n) (1) and {[Co(TPA)-(mu(2)-OH)] (H2O)(2)}(n) (2) (HTPA = 4-(1,2,4-triazol-4-yl)-phenylacetic acid) were solvothermally synthesized and fully characterized. Interesting 1D Co2+-Cl or Co2+-mu(2)-OH chain structures were observed. By carefully adjusting the reaction conditions; a new 3D metal-organic framework (MOF) with a formula of {[Co-7(TPA)(6)(u(3)-OH)(4)(mu(2)-OH)(2)(H2O)(4)]-(TPA)(2)(DMF)(3)(H2O)(3)}(n) (3) was obtained. MOF 3 is built from Co-7 clusters and fully deprotonated TPA ligands, which, display a cubic pcu topology. Factors that influence the structures of the three TPA-based complexes, as well as their magnetic properties, were investigated in detail. The heptanuclear-Co(II)-cluster-based MOF 3 shows interesting Magnetization dynamics at low temperature.