Synthesis,Structures And Applications Of Polynuclear Lanthanide Complexes Based On Acylhydrazone Ligands

Acylhydrazone ligands have attracted extensive attention owing to ease to synthesize,various coordination modes and strong coordination ability.Lanthanide have potential applications in optics,electricity and magnetism because of their unique electronic structures.In recent years,with the development of coordination chemistry,a large number of polynuclear lanthanide complexes with novel structures and excellent properties have been prepared,making great progresses in luminescent materials,fluorescent sensors,single-molecule magnets,magnetic refrigeration,catalysis and biomimetics,etc.In this thesis,focusing on the construction and functional application of polynuclear lanthanide complexes,two asymmetric acylhydrazone ligands were designed and synthesized,respectively.After self-assembly with transition/lanthanide ions,seven novel heteronuclear 3d-4f,s-f complexes and homonuclear lanthanide complexes were prepared.Then,their application properties such as single-molecule magnets,fluorescent sensors,and near-infrared luminescence were further studied.The main content includes the following three parts:?1?.This section introduced the acylhydrazone ligands and lanthanide complexes,and described their crystal structures and applications in the recognition,near-infrared luminescence,single-molecule magnets and catalysis.And then,the research progress on the heteronuclear 3d-4f complexes as single-molecule magnets was summarized.Finally,we briefly reviewed luminescence mechanism and fluorescence sensing application of the luminescent metal-organic frameworks?MOFs?.?2?.An asymmetrical acylhydrazone ligand H₃L¹ with two coordination pockets that show different binding preferences for selective coordination with Ln^III?Ln=Dy,Tb?and Cu^II ions has been synthesized to construct two novel octanuclear complexes.Direct current magnetic susceptibilities demonstrated the presence of strong ferromagnetic interaction between Cu^II and Ln^III and magnetic anisotropy.Furthermore,alternating current?ac?magnetic measurements illustrated that these two complexes exhibited typical zero-field single-molecule magnet behavior.The effective energy barrier(U_eff)for{Cu₄Dy₄}was 54 K,which is one of the highest U_eff values yet reported for Cu^II/Ln^III single-molecule magnets.?3?.On the basis of ligand H₂L¹,ligand H₂L² with different terminal group has been designed and synthesized.Based on H₂L¹ and H₂L²,we prepared five varied polynuclear lanthanide complexes.A rare heteronuclear s-f metal-organic framework?MOF?was constructed based on H₂L¹ and the luminescence properties was investigated.This MOF material showed highly sensitive,selective,anti-interference and reversible detection of Fe³⁺and MnO₄^-in CH₃CN.Additionally,the possible sensing mechanism was explored.Based on H₂L² and Yb^III salts with different anions,three Yb-complexes were synthesized.The near-infrared luminescence properties of these complexes were characterized,and the results showed better antenna effect of ligand H₂L².