Synthesis,Structures And Magnetic Properties Of Lanthanide Polynuclear Clusters Based On Pyridine N-oxide Diacylhydrazone

In recent years,the SMMs have attracted much attention owing to their unique properties and potential applications in various fields,such as data storage,spintronics and quantum computing devices,etc.In particular Lanthanide(Ln)clusters are regarded as the good candidates of SMMs because of their significant single ion anisotropy.Acylhydrazones ligands have play important roles in the construction of these Ln SMMs and make remarkable progress.However,most of the reported acylhydrazones Ln-SMMs are low nuclear cluster,and the types of molecular structure were still limited,which limited the exploration of the SMM properties to certain extent.Thus it would be significant for the studies on Ln-SMMs to construct complexes with novel structures and excellent magnetic properties through judicious choose of novel acylhydrazones ligands.In this context,we synthesized two novel acylhydrazones ligands based on pyridine N-oxide parent and different terminal groups,namely,pyridine aldehyde-pyridine-2,6-dimethyhydrazones-N-oxide(H2papho)and ethoxy-o-hydroxybenzaldehyde-pyridine-2,6-dimethyhydrazones-N-oxide(H4esapho),respectively.Finally,three series of complexes were obtained through the optimization of reaction methods and conditions.Their structures and magnetic properties were further investigated.The research contents were shown as follows:1.The solvothermal reactions of Ln(NO3)3 with the H2papho afforded three Ln complexes,namely,[Dy?11(papho)4(NO3)14(?3-OH)4(?2-OH)4(H20)2](OH)3·2CH3OH(1),[Ho?11(papho)4(NO3)14(?3-OH)4(?2-OH)4(H20)2](OH)3-2CH3OH(2)and[Er?11(papho)4CNO3)14{?3-OH)4(?2-OH)4(H2O)2](OH)3·2CH3OH(3).These clusters are isomorphous and crystallize in the monoclinic space group C2/c.The H2papho ligands are deprotonated completely in complexes and display ?4-?1:?1:?2:?2:?2:?1:?1 mode,constructing a undecanuclear cluster containing a vertex shared defects cubane unit and two dinuclear units with OH-and NO3-.The magnetic study reveals that 1 display slow magnetic relaxation behavior.2.The reactions of Ln(NO3)3 with the H4esapho afforded a series of lanthanide complexes,namely,[Ln?6(esapho)3(NO3)6(CH3OH)6]·8CH3OH·2CH3CN(Ln=Dy(4),Ho(5)and Er(6)).These complexes are isomorphous and crystallize in the monoclinic space group Pn.The esapho4-show ?6:?1:?2:?1:?2:?2:?2:?1:?2:?1 and ?4:?1:?1:?2:?2:?2:?1:?1 coordination modes.Two of them chelate six Ln(?)ion to form a rare linear hexanuclear cluster.With the little change of the synthetic conditions,the solvethermal reactions of H4esapho with Ln(NO3)3 afforded a pentanuclear cluster[Dy?5(Hesapho)5(CH3OH)2]·6CH3OH(7).Complex 7 is crystallize in the monoclinic space group P21/c,and can be regarded as a combination of a {Ln3} triangle and a{Ln2} unit.The Hesapho3-ligands in 7 show three different coordination modes:?4:?1:?1:?2:?1:?1:?1:?2:?1,?4:?1:?2:?1:?1:?2:?1:?1 and The magnetic study reveals that complexes 4 and 7 show different SMM behaviors.