Investigation Of Diverse Structures Based On Heptanuclear Co Cluster From 0D To 3D Metal Organic Framework:Magnetism And Application In Batteries

According to the topology of structures,metal-organic complexes can be divided into:clusters,one-dimensional?1D?chain,two-dimensional?2D?layer,and three-dimensional?3D?skeleton.Due to their potential applications in catalysis,electrochemistry,fluorescence,gas adsorption and separation,and magnetism,extensive researches have been aroused.In this paper,we selected flexible ligand bis-tris propane?H₆L?as the main ligand,dicarboxybiphenyl?BDA?and isophthalic acid?IPA?as auxiliary ligands to prepare five different structures of metal-organic complexes by using cobalt salts containing different anions.We explored the synthesis of five compounds in detail,and analyzed the effects of ligands,solvent molecules on the structure of multimetallic complexes.At the same time,based on the different structural characteristics of the five complexes,we tested the potential applications of these compounds in magnetism,gas adsorption and lithium-ion batteries.This paper mainly includes the following two works:?1?Induced by different anions of cobalt salts and solvents,three complexes Co₄^?Co₃^??H₂L?₃Cl₅?MeOH??1?,[Co₄^?Co₃^??H₂L?₃?CH₃COO?₄?HCOO?.H₂O]_n?2?,and[Co₄^?Co₃^??H₂L?₃?HCOO?₄?NO₃?.2H₂O]_n?3?based on heptanuclear[Co₄^?Co₃^?]cluster with structures from 0D to 3D metal organic framework?MOF?have been solvothermally synthesized by using H₆L ligand.Compound 1 is the first 0D heptanuclear cluster based on H₆L.Compound 2 crystallizes in chiral space group P2₁2₁2₁ and consists of 1D chiral helical chain.Complex 3 exhibits a 3D network structure.The compounds 1 and 3 display dominant ferrimagnetic interactions,while compound 2 exhibits antiferromagnetic interactions.The electric performance of the Co₃O₄ prepared by calcining compound 2 in Lithium Ion Batteries?LIBs?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.?2?Based on the above work,we successfully synthesized two compounds[Co₄^?Co₃^??H₂L?₃?BDA??CH₃COO?₄.2H₂O]_n?4?and[Co₄^?Co₃^??H₂L?₃?IPA??HCOO?₃?DMF?.H₂O]_n?5?by employing BDA and IPA ligands,respectively.Compound 4 possesses a 1D zigzag-like chain structure,while compound 5presents a 3D microporous structure.Magnetic measurements show that compound 4 displays dominant ferrimagnetic interactions and compound 5 exhibits antiferromagnetic interactions.The N₂ and I₂ adsorption properties of compound 5 have been explored.Meanwhile,we also investigated the catalytic effect of I₂@compound 5 for cyanosilylation of benzaldehyde.