Synthese,Structures And Magnetic Properties Of Dysprosium Coordination Complexes Based On Flexible Arylhydrazone Ligand

Because of the magnetic bistability and quantum tunneling of the magnetization,single-molecule magnets?SMMs?have a wide application prospect in the fields of ultrahigh-density information storage and quantum computing.In this dissertation,a series of new rare earth complexes with novel structure are designed and synthesized by taking rare earth ions as the main spin carriers,and their structure and magnetic properties are systematically studied.The aim is to further reveal the relationship between the structure and magnetism of rare earth molecular magnets and to provide reference for the development of new rare earth molecular magnets.Firstly,Three di-nuclear Dy^III complexes[Dy₂?LH₂?₂?tfa?]·Cl·3DMF?1?,[Dy₂?LH₂?₂?MeO??SCN?]·MeOH?2?and[Dy₂?LH₂?₂?MeOH?Cl]·Cl·2MeOH?3?were structurally and magnetically characterized.The Dy1/Dy2 centers in these complexes are all nine-coordinate with C_4v symmetry environments.All complexes show significant single-molecule magnetic behavior under zero applied dc field with relaxation process be diverse from each other.Ab initio calculations substantiate that all Dy^III sites in complexes 1-3 show relatively axial crystal-fields dominated by the interaction with the Dy^III ion and the aryloxy oxygen of the ligands.Exceptionally,the antiferromagnetic intermolecular exchange found in complex 2 was sufficiently strong to mask the ferromagnetic intramolecular exchange as revealed by ab initio calculations.Secondly,Acyclicpentucleardysprosiumcomplex[Dy₅?L?₂?OAc?₅?CO₃??H₂O?]·MeOH?4?was designed and synthesized.The complex contains a bridged carbonate anion derived from the fixation of atmospheric CO₂ in the coordination reaction.The carbonate anion is embedded in the central cavity of the entire molecule and participates in the coordination to five Dy^III sites.Ac susceptibility test showed that the complex had the typical characteristics of SMMs under zero external field conditions.Meanwhile,the??versus?plots showed a slightly increased trend in the high frequency region below 4 K,indicating the existence of a possible faster relaxation path.The flexible arylhydrazone ligand used in the synthesis of this complex is a good building block.Its numerous coordinating atoms can provide more coordination modes and expand the synthesis of more novel complexes in the future.It's worth mentioning that the capture of CO₂ molecules in the air is also worthy of attention.