Mononuclear lanthanide complexes incorporating an anthracene group: structural modification, slow magnetic relaxation and multicomponent fluorescence emissions in Dy compounds

Four mononuclear lanthanide complexes, [Ln(hfac)(3)(depma)(H2O)] [Ln(III) = Dy (1), Gd (2)], [Dy(hfac)(3)-(depma)(2)](2)center dot H2O (3) and [Gd(hfac)(3)(depma)(2)]center dot 2H(2)O (4), have been obtained (hfac = hexafluoroacetyl-acetonate, depma = 9-diethylphosphonomethyl anthracene) by using one (for 1 and 2) or two (for 3 and 4) depma molecules to substitute coordination water molecules of Ln(hfac)(3)(H2O)(2). It was found that the number of introduced depma ligands can modify the coordination geometry of Ln(III) ions, showing a distorted biscapped triangular prism geometry in isostructural 1 and 2 and a distorted square-antiprismatic geometry in 3 and 4. Magnetic studies reveal that both 1 and 3 show field-induced slow magnetic relaxation under the applied dc field of 1000 Oe. The solid-state fluorescence measurements indicate the presence of multicomponent emissions in 1 and 3, including ligand-centered (LC) emissions from hfac and depma, and yellow emission from Dy(III) ions and only ligand-centered (LC) emissions in 2 and 4.