Two new lanthanide-nitronyl nitroxide complexes: Magnetic and fluorescence properties

Abstract

Two new lanthanide complexes of nitronyl nitroxide radical have been synthesized and characterized on the structure, magnetism and fluorescence: [Ln(hfac)3(NITPh-(OCH3)2)2](Ln = (Tb(1),Dy(2)), (NITPh-(OCH3)2 = 2-(3′,4′-dimethoxy-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide); hfac = hexafluoroacetylacetonate). Two complexes crystallize in monoclinic space group C2/c, which have similar mononuclear structures. The central metal ion is eight coordinated by six oxygen atoms from three hfac molecules and two oxygen atoms from two nitronyl nitroxide radicals. The varying temperature magnetic susceptibility indicates that there are weak antiferromagnetic interaction between metal ions and nitronyl nitroxide radicals in complexes 1 (zJ′ = −0.145 cm−1) and 2 (zJ′ = −0.140 cm−1). Ac magnetic susceptibility studies exhibit no single-molecule magnet behavior in complexes 1 and 2. In addition, the fluorescence properties of 1 show that it is an excellent fluorescent probe of recognizing Cr2O72− anion. Because of the linear relationship at low concentration and detection limit reached 1 × 10−7 M, it can be used as a luminescence-based sensor for quantitative analysis.