Syntheses,Structures And Magnetic Properties Of Polyalcohol Ligands-based Lanthanide Metal Clusters

Due to the nanoscale molecular structures and beautiful topological skeletons,and their unique properties exhibited in so many fields,such as optical,electric,magnetic and catalytic,the lanthanide metal clusters have aroused widespread concern.Among the studies of the lanthanide metal clusters,the most important is the design and synthesis based on the target propertity.And one of the difficulties in the synthesis is the controlling of the hydrolysis reaction of lanthanide ions.Ligand-control method is the identified good way to overcome this peoblem.In this method,the point is choosing a suitable and critical ligand.As a multiple hydroxyl ligand,polyalcohol ligand can play a similar role with buffer,which can control the pH of the reaction as high as possible under the premise of no sediment.Based on the above,this article adopts a plurality of polyalcohol ligands to synthesize a series of lanthanide metal clusters and studys on the relationships between their structures and magnetic properties.The main contents are as follows:1.We chose amino acid polyalcohol ligands to obtain two Ln15 clusters,and studied their structures and magnetic properties.Between them,the Gdis exhibited large magnetocaloric effect and the Dyis showed the property of single molecular magnets(SMMs);Under appropriate reaction condition,we chose amino polyalcohol ligand to synthesize a series of mix-valenced Ln-Co clusters.We also found that the ligand played an important role inchelating the lanthanide metal ions and the transition metal ions.2.Based on myo-inositol ligand with six hydroxyl groups,we obtained two diffirent configurations Dy2 clusters and three Ln3 clusters with the same structure.Among them,the Dy2 clusters showed significant SMM properties.During the synthesis,we found that little change of the reactant rario and reaction condition had a great influence on the products’ structures,and furethermore affected their magnetic properties.3.Using the ligand 1,2,3-Cyclohexanetriol to control the hydrolysis of the lanthanide metal ions and protect the stability of the metal core of the clusters,we got three double-cage-like Ln37 clusters with the same stuctures.The Ln37 compound is by far the largest odd-numbered lanthanide cluster synthesized to date Magnetic characterization found that the Gd37 cluster shows a large magnetocaloric effect.