Synthesis, Structure, Luminescence And Magnetic Properties Of Dimethyl Heptanedione Rare Earth Complexes

Lanthanides complexes have wide applications in luminescent materials and magnetic materials due to their unique luminescence and magnetic properties.However,the studies on the relationship between the structure and properties of rare earth complexes are scarce.Therefore this paper chose 2,6-dimethyl-3,5-heptanedione?Hdmh?react with various LnCl₃?6H₂O,auxiliary ligand affording three series of 15new?-diketone of rare earth complexes 1-15.Their single crystal structures were determined by X-ray crystallography.Their molecular magnetism and near infrared luminescent have been studied:Magnetic analysis reveals that complexes 2 and 3 are single molecule magnets but not for complex 1.Strikingly,complex 2 exhibits mainly single slow relaxation under 0dc field and double slow relaxation under optimized dc field.In contrast,complex 3exhibits double slow relaxation under 0 dc field and single slow relaxation under optimized dc field.The origins of the double slow relaxation modes of complex 2 have been verified by dilution sample of complex 2.Magnetic test shows that the three complexes 4-6 are single molecular magnets,and don't exhibit zero field quantum tunneling at low temperature.Their coupling constant J were further investigated.Complexes[Ln?dmh?₃?MeOH?][Ln=Ho?7?,Yb?10?,Nd?13?],[Ln?dmh?₃?2,2'-bpy?]₂[Ln=Ho?8?,Yb?11?,Nd?14?]and[Ln?dmh?₃?phen?][Ln=Ho?9?,Yb?12?,Nd?15?]exhibit the characteristic near infrared luminescence of lanthanide ions.The auxiliary ligand can improve the intensity of the near infrared luminescence.