Syntheses, crystal structures, magnetic and luminescence properties of five novel lanthanide complexes of nitronyl nitroxide radical

Five novel Ln(III) complexes based on a new nitronyl nitroxide radical have been synthesized, characterized structurally and magnetically: [Ln(hfac)(3)(NITPh-3-Br-4-OMe)(2)] (Ln(III)=Eu(1), Gd(2), Tb (3), Dy(4), Ho(5); hfac=hexafluoroacetylacetonate; and NITPh-3-Br-4-OMe=2-3'-Br-4'-methoxyphenyl- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide). The single-crystal structures analyses show that these complexes have similar mononuclear tri-spin structures, in which central Ln(III) ions are all eight coordinated by three hfac molecules and two NITPh-3-Br-4-OMe radicals. The variable-temperature magnetic susceptibility studies reveal the antiferromagnetic interactions between the paramagnetic ions (Ln(III) and radicals) in complexes 1, 2, 3 and 5 and ferromagnetic interaction in complex 4. The luminescence characterizations of complexes Eu(1), Tb(3) and Dy(4) are also studied in this paper. (C) 2013 Elsevier Inc. All rights reserved.