Synthesis, Structure, Magnetic and Photoluminescent Properties of Dysprosium(III) Schiff Base Single‐Molecule Magnets: Investigation of the Relaxation of the Magnetization

We report here the synthesis, structure, magnetic and photoluminescent properties of three new bifunctional Schiff‐base complexes [Dy(L 1 ) 2 (py) 2 ][B(Ph) 4 ]⋅py ( 1 ), [Dy(L 1 ) 2 Cl(DME)] ⋅ 0.5DME ( 2 ) and [Dy(L 2 ) 2 Cl] ⋅ 2.5(C 7 H 8 ) ( 3 ) (HL 1 =Phenol, 2,4‐bis(1,1‐dimethylethyl)‐6‐[[(2‐methoxy‐5‐methylphenyl)imino]methyl]; HL 2 =Phenol, 2,4‐bis(1,1‐dimethylethyl)‐6‐[[(2‐methoxyphenyl)imino]methyl]). The coordination environment of the Dy 3+ ion and the direction of the anisotropic axis may be controlled by the combination of the substituent groups of the Schiff bases, the nature of the counter‐ions (Cl − vs . BPh 4 − ) and the coordinative solvent molecules. A zero‐field slow relaxation of the magnetization is evidenced for all complexes but strong differences in the relaxation dynamics are observed depending on the Dy 3+ site geometry. In this sense, complex 1 exhibits an anisotropy barrier of 472 cm −1 , which may be favourably compared to other related examples due to the shortening of the Dy−O bond in the axial direction. Besides, the three complexes exhibit a ligand‐based luminescence making them as bifunctional magneto‐luminescent systems.