Multifunctional properties existing in Ln–nitronyl nitroxide single-chain magnets

Abstract

Taking advantage of a nitronyl nitroxide radical ligand 8-QNNIT (1) (8-quinolyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) and Ln(hfac)₃·2H₂O (Ln^III = Tb 2 and Dy 3; hfac = hexafluoroacetylacetonate), two Ln–radical one-dimensional chains [Ln(hfac)₃(8-QNNIT)]_n were constructed. The magnetic properties, thermodynamics and optical behavior of both compounds were observed, exhibiting polyfunctionality of the 2p–4f system. Complexes 2 and 3 show typical single-chain magnet (SCM) properties with temperature-dependent relaxation peaks giving an effective energy barrier (U_eff/k_B) of 47.4 K (2) and 64.6 K (3). Luminescence spectra and ultravioletvisible (UV-vis) absorption spectra of the Tb compound, and UV-vis absorption spectra and thermodynamics properties of the Dy complex were investigated. As far as we know, the Dy complex is the first SCM with thermodynamics behavior and optical properties comparable to those of multifunctional magnetic materials. This study aims to provide a new way and field of vision for the construction of 2p–4f heterospin multi-functional materials.