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

Abstract

Polymetallic complexes with interesting multifunctions have attracted extensive investigation. Synthesized through the use of different cobalt salt anions and solvents, five complexes, namely [CoII4 CoIII3 (H2 L)3 Cl5 (MeOH)] (1), [CoII4 CoIII3 (H2 L)3 (CH3 COO)4 (HCOO)⋅H2 O]n (2), [CoII4 CoIII3 (H2 L)3 (HCOO)4 (NO3 )⋅2H2 O]n (3), [CoII4 CoIII3 (H2 L)3 (bda)(CH3 COO)4 ⋅2H2 O]n (4), and [CoII4 CoIII3 (H2 L)3 (ipa)(HCOO)3 (dmf)⋅H2 O]n (5) (H6 L=bis-tris propane; BDA=biphenyl-4,4'-dicarboxylic acid; IPA=isophthalic acid; DMF=N,N-dimethylformamide), based on the heptanuclear {CoII4 CoIII3 } 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 H6 L. Compound 2 crystallizes in the chiral space group P21 21 21 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 Co3 O4 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.