Structure, magnetic properties and fluorescence selectivity of mono-nuclear [Ln(hfac)3]-(radical)2 compounds.

• Four new mono-nuclear Ln-radical complexes have been successfully prepared. • Tb complex displays field-induced slow relaxation of the magnetization. • Tb complex acted as luminescence-based probe for detecting Fe3+ and Cr2O72− ions. A series of mono-nuclear rare earth-radical compounds [Ln(hfac) 3 (NIT-Ph-3-COOMe) 2 ]·0.5C 7 H 16 (LnIII = Gd(1) , Tb(2) , Dy(3), Ho (4)) were get by reaction of nitroxide radical NIT-Ph-3-COOMe with Ln(hfac) 3 ·2H 2 O (NIT-Ph-3-COOMe=2-(3-(methoxycarbonyl)-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; hfac=hexafluoroacetylacetonate). Each Ln(Ⅲ) ion in four complexes is an octa-coordination configuration, in which two O atoms from NO units of two NIT-Ph-3-COOMe radicals and six O atoms are derived from three hfac co-ligands. Magnetic measurements indicate that a ferromagnetic interaction between GdIII and nitroxide radicals, while magnetic coupling of two NOs transmitted by GdIII ion is antiferromagnetic. For compound 2 , non-zero out-of-phase signals (χ″) were gained at 3000 Oe, confirming field-induced magnetic relaxation behavior. Furthermore, fluorescence properties of 2 were investigated, which indicated that it can be used as a highly sensitive and selective fluorescence probe of Fe3+ cation and Cr 2 O 7 2− anion. Four new mono-nuclear Ln-radical complexes have been successfully prepared. The Gd–nitroxide exchange is ferromagnetic while the magnetic coupling between two nitroxide radicals is antiferromagnetic. Tb complex displays field-induced slow relaxation of the magnetization. Moreover, it can be acted as luminescence-based probe for quantitative and highly sensitive detection of Fe3+and Cr 2 O 7 2− ions. [Display omitted] [ABSTRACT FROM AUTHOR]