Abstract
We have designed and synthesized two new Co-CPs by modulating the concentration of cobalt ions, namely [Co3(HL)2(4,4′-bibp)3(H2O)4]n (1) and {[Co9(L)4(4,4′-bibp)4(H2O)6(μ2-OH)2]·4,4′-bibp·2H2O}n (2) (H4L = 1,1′,2′,1″-terphenyl-4,4′,4″,5′-tetracarboxylic acid and 4,4′-bipb = 1,4-di(pyridin-4-yl)benzene). CP 1 is a three-dimensional (3D) pillar-layered network constructed by HL3− and bridging 4,4′-bibp co-ligands with a 10-connected (424.512.68.7) topology. CP 2 is a 3D reticular framework with (4,4,5,5,6)-connected topology. The structural diversity of the two CPs suggests that the cluster numbers and the different local coordination geometries of Co(II) ions can be induced by the reaction material ratio. Focusing on the bridging system, CP 1 cnsists of centrosymmetric trinuclear octahedral cobalt(II) units, and within the units, the cobalt(II) ions are found to be ferromagnetically coupled. CP 2 cnsists of centrosymmetric nonanuclear cobalt(II) units, including five octahedral and four trigonal-bipyramidal cobalt(II) ions. Antiferromagnetic interactions are observed in the partial triangular units, and also in the other parts, showing an overall antiferromagnetic behavior.
Two 3D Co(II)-based MOFs have been synthesized and showed different topologies due to the various SBU. It was found that ferromagnetically interaction and antiferromagnetic interactions are observed for 1 and 2, respectively. [Display omitted]
•Two new Co-CPs by modulating the concentration of cobalt ions.•Magnetic study of multinuclear cobalt Coordination polymer.•The topology of (424.512.68.7) trinuclear and (4.4.5.5.6) nine-nuclear.