Dy4 and Dy5 complexes based on tautomeric hydrazone Schiff-base ligand regulated by temperature showing single-molecule magnet behaviour

Two dysprosium complexes [Dy4(H2L)6]⋅4H2O (Dy4) and [Dy5(H2L)(HL)2(L)(µ3-OH)2Cl⋅(H2O)⋅(MeCN)2]⋅4MeOH⋅7H2O (Dy5) (H4L = (N',N'''E,N',N'''E)-N',N'''-(pyridine-2,6-diylbis(methanylylidene))bis(2-hydroxybenzohydrazide)) based on hydrazone Schiff-base ligand were synthesized, which could be regulated by controlling temperature (Dy4, below 293 K and Dy5, over 308 K). Magnetic studies show that complex Dy4 is a typical field-induced single-molecule magnet with an effective energy barrier (Ueff) of 42.9 K under 1 kOe dc field. Complex Dy5 is a zero dc field single-molecule magnet with an effective energy barrier (Ueff) of 4.18 K. The results indicate the synthesis of lanthanide complexes is sensitive to substitute of ligand and temperature.