High magnetization reversal barriers in luminescent dysprosium octahedral and pentagonal bipyramidal single-molecule magnets based on fluorinated alkoxide ligands

Abstract

We report the synthesis and structures of three luminescent dysprosium(iii) complexes based on fluorinated alkoxide ligands of formulas [Dy(L1)2(THF)4][BPh4]·0.5THF (1), [Dy(L2)2(THF)5][BPh4]·2.5THF (2) and [Dy(L3)2(THF)5][BPh4]·2THF (3) (L1= (CF3)3CO−, L2= C6F5C6F4O−, L3= C6F5C(CH3)O−). Despite the different dysprosium ion geometries (octahedralvs.distorted pentagonal bipyramidal), these systems exhibit a single-molecule magnet (SMM) behavior, but with distinct relaxation dynamics. Moreover, a typical dysprosium-based luminescence is observed for the three complexes, which make them bifunctional magneto-luminescent SMMs. Remarkably, complex3exhibits a high anisotropy barrier of 1469 cm−1and a blocking temperature of 22 K, making it one of the most performant alkoxide-based SMMs with the highest blocking temperature for a luminescent SMM.