Manipulating Solvothermal Coordination-Catalyzed In Situ Tandem Reactions to Construct Dysprosium-Based Complexes with Different Shapes and Zero-Field SMM Behaviors.

Abstract

By changing the coordination anions (OAc- and Cl-), reaction temperature, solvent, and ligand substituents, four Dy(III)-based complexes were obtained by directed synthesis, which are [Dy4(L1)2(L2)2(OAc)4]·4C2H5OH·3H2O (1, L1 = 1,3,4-thiadiazole-2,5-diamine, H4L2 = 6,6'-(((1,3,4-thiadiazole-2,5-diyl)bis(azanediyl))bis(((3-ethoxy-2-hydroxybenzyl)oxy)methylene))bis(2-ethoxyphen), [Dy4(L3)4(OAc)4]·C2H5OH·H2O (2, H3L3 = 2-(((5-amino-1,3,4-thiadiazol-2-yl)amino)((3-ethoxy-2-hydroxybenzyl)oxy)methyl)-6-ethoxyphenol)), [Dy6(L4)4(L5)2(μ3-OH)4(CH3O)4Cl4]Cl2 (3, H2L4 = 2-hydroxy-3-methoxybenzaldehyde, H2L5 = 2-(((5-amino-1,3,4-thiadiazol-2-yl)amino)(hydroxy)methyl)-6-methoxyphenol), and [Dy6(L6)4(L7)2(μ3-OH)4(CH3O)4Cl4]Cl2·2H3O (4, H2L6 = 2-hydroxy-3-ethoxybenzaldehyde, H2L7 = 2-(((5-amino-1,3,4-thiadiazol-2-yl)amino)(hydroxy)methyl)-6-ethoxyphenol). A series of acetal products (H4L2, H3L3, H2L5, and H2L7) were obtained through dehydration in situ tandem reactions. Magnetic studies show that complexes 1-4 exhibited different single-molecule magnet behavior under zero-field conditions. The best fitting results showed that under zero DC field, the effective energy barriers (Ueff) and magnetic relaxation times (τ0) of complexes 1-4 are Ueff = 117.0 (2.1) K and τ0 = 6.07 × 10-7 s; Ueff = 83.91 (1.5) K and τ0 = 4.28 × 10-7 s; Ueff = 1.28 (0.2) K and τ0 = 0.73 s, and Ueff = 104.43 (13.3) K and τ0 = 8.25 × 10-8 s, respectively.