Copper(ii)-terbium(iii) Single-Molecule Magnets linked by photochromic ligands

摘要

Two assemblies composed of single-molecule magnets (SMMs) linked by photochromic ligands, [Cu~(II)_2Tb~(III)_2(L)_2(NO_3)_2(dae-o) 2]·2(n-BuOH) (1) and {[Cu~(II)Tb~(III)(L)(n- BuOH)_(0.5)]_2(dae-c)_3}·5(DMF)·4(n- BuOH)·2(H_2O) (2), were synthesized by reacting the SMM [Cu~(II)Tb~(III)(L)(NO_3)_3] (H_2L = 1, 3-bis((3-methoxysalicylidene)amino)propane) and photochromic molecules, H_2dae-o and H_2dae-c, which are open- and closed-ring isomers of 1, 2-bis(5-carboxyl-2-methyl-3-thienyl)perfluoropentene (H _2dae), respectively. 1 has a tetranuclear ring-like structure comprised of two [CuTb] units and two dae-o~(2-) ligands. On the other hand, 2 has a one-dimensional ladder-type structure involving the [CuTb] and dae-c~(2-) units in a 3:2 ratio. Magnetic studies revealed that 1 and 2 had ferromagnetic interactions between the Cu~(II) and Tb~(III) ions and that both compounds exhibited frequency dependence of ac susceptibilities owing to freezing the magnetization of the [CuTb] SMM. Upon irradiation with ultraviolet light and visible light, an absorption band at ～600 nm changed, indicating that photochromic reactions involving the dae~(2-) ligands occurred. After irradiation, the magnetic behaviour of 1 did not change, whereas magnetic behaviour of 2 changed, due to the modification of intermolecular environment.