Diverse Structures Based on a Heptanuclear Cobalt Cluster with 0D to 3D Metal–Organic Frameworks: Magnetism and Application in Batteries

Polymetallic complexes with interesting multifunctions have attracted extensive investigation. Synthesized through the use of different cobalt salt anions and solvents, five complexes, namely [CoII4CoIII3(H2L)3Cl5(MeOH)] (1), [CoII4CoIII3(H2L)3(CH3COO)4(HCOO)⋅H2O]n (2), [CoII4CoIII3(H2L)3(HCOO)4(NO3)⋅2H2O]n (3), [CoII4CoIII3(H2L)3(bda)(CH3COO)4⋅2H2O]n (4), and [CoII4CoIII3(H2L)3(ipa)(HCOO)3(dmf)⋅H2O]n (5) (H6L=bis‐tris propane; BDA=biphenyl‐4,4′‐dicarboxylic acid; IPA=isophthalic acid; DMF=N,N‐dimethylformamide), based on the heptanuclear {CoII4CoIII3} cluster with structures from 0D to 3D metal–organic frameworks (MOFs) have been solvothermally synthesized. Compound 1 is the first 0D heptanuclear cluster based on H6L. Compound 2 crystallizes in the chiral space group P212121 and consists of a 1D chiral helical chain. Complex 3 exhibits a 3D network structure. Compound 4 possesses a 1D zigzag‐like chain structure. Finally, compound 5 was obtained as a 3D microporous structure. Compounds 1, 3, and 4 display dominant ferrimagnetic interactions whereas compounds 2 and 5 exhibit antiferromagnetic interactions. Moreover, the Co3O4 prepared by calcining compound 2 presents a reversible capacity of 1122.9 mA h g−1 at 0.2 A g−1 after 100 cycles and an excellent rate capability, which suggests that coordination compounds with a 1D chain structure are outstanding precursors for preparing anode materials for lithium ion batteries. Tuning cluster structures. Five complexes based on the heptanuclear {CoII4CoIII3} cluster with structures from 0D to 3D metal–organic frameworks (see figure) have been synthesized and their potential applications in magnetism, batteries with high reversible capacity and excellent rate capability, reversible iodine adsorption, and heterogeneous catalysis have been explored.