Solvent-induced single-molecule magnet behavior and near-infrared luminescence properties of rare earth complexes

Abstract

We synthesized two series of dinuclear rare earth complexes [RE₂L₂(acac)₂(H₂O)₂]·i-PrOH (RE = Y (1), Eu (2), Dy (3), Ho (4), Er (5) and Yb (6)) and Dy₂(L₂)₂(acac)₂(C₂H₅OH)₂ (7) (H₂L = pyridine-2-carboxylic acid [(2-hydroxy-3-methoxyphenyl)methylene]hydrazide, Hacac = acetylacetone). The static (dc) magnetic susceptibility shows that the weak ferromagnetic interaction exists in Dy^III of 3 and 7. Furthermore, the study of magnetization dynamics manifests that 7 possesses an energy barrier of about 45 K at a zero dc field, while the energy barrier of 3 is 42.93 K under the applied 800 Oe dc field by using a solvent-controlled crystallization. Interestingly, the energy barrier of 7 could attain 80.39 K through deteriorating the QTM. Besides, near-infrared luminescence analysis shows that the ligands can work as effective sensitizing agents of 5 and 6. We observed the characteristic peaks of Er^III and Yb^III ions, meanwhile, complex 5 has a potential application for optical systems because the maximum peak is located in the third telecommunication window about 1531 nm.