Near-infrared luminescence and magnetic properties of dinuclear rare earth complexes modulated by β-diketone co-ligands

Abstract

Seven phenoxo–O and carbonyl–O bridged dinuclear rare earth complexes have been assembled utilizing 3-methoxysalicylaldehyde-2-aminobenzoylhydrazone (H₂L) and three β-diketone ligands (Hdbm = 1,3-diphenyl-1,3-propanedione, Hacac = acetylacetone, Hbeac = 1-phenyl-1,3-butanedione): [RE₂L(HL)(acac)₃]·3CH₃CH₂OH (RE(III) = Eu (1), Tb (2), Dy (3), Ho (4), Er (5)), [Yb₂L₂(dbm)₂(CH₃OH)₂]·CH₃OH (6), [Dy₂L(HL)(beac)₃] (7). Complexes 5 and 6 show the characteristic emission peaks of the corresponding Er³⁺ and Yb³⁺ ions, respectively. Studies on the magnetic properties of the complexes reveal that complexes 3 and 7 exhibit slow magnetic relaxation behaviors, typical of SMM behaviors, resulting in an energy barrier of 140 K for 3 and 75 K for 7. Meanwhile, this research demonstrates that the magnetic properties can be modulated by subtle changes in the coordination environment resulting from the changes in the co-ligand substituents.