Slow magnetic relaxation and field-induced metamagnetism in nitronyl nitroxide-Dy(III) magnetic chains.

The combination of lanthanide ions and nitronyl nitroxide radicals resulted in four new Ln-radical one-dimensional compounds, namely, [Ln(hfac)3{NIT-Ph(OMe)2}]n(Ln(III) = Sm (1), Eu (2), Gd (3), Dy (4); hfac = hexafluoroacetylacetonate; NIT-Ph(OMe)2 = 2-(2',4'-dimethoxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide). The four complexes were found to be isomorphous and exhibit nitronyl nitroxide radicals-bridged lanthanides linear chains. DC magnetic susceptibilities show that the directly bonded nitronyl nitroxide interacts ferromagnetically with Gd and Dy ions. The Dy complex exhibits three-step metamagnetism and frequency-dependent ac magnetic susceptibilities, indicating single-chain magnet behavior. This work shows that the magnetic behaviors of one-dimensional Ln-nitronyl nitroxide chains can be fine tuned by the substituents of the radicals.