Asymmetric Assembly of Chiral Lanthanide(III) Tetranuclear Cluster Complexes Using Achiral Mixed Ligands: Single-molecule Magnet Behavior and Magnetic Entropy Change

[Image: see text] It is challenging to use achiral ligands to spontaneously construct chiral molecular magnets. In this work, two new Ln(4) cluster complexes based on N,N′-(1,3-propanediyl)bis[N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]amine] (H(6)L) have been assembled, which are crystallized in a chiral space group due to the asymmetric distribution of acetate (OAc(–)) groups and hexafluoroacetylacetonate (F(6)acac(–)) groups on both sides of the parallelogram-like Ln(4) core. Complex 1, [Dy(4)(H(3)L)(2)(OAc)(3)(F(6)acac)(3)]·5MeOH·2H(2)O, exhibits single-molecule magnet properties at the zero field with the U(eff)/k value of 48.4 K; notably, besides the Orbach process, the Raman process is also prominent for the magnetic relaxation of 1. Complex 2, [Gd(4)(H(3)L)(2)(OAc)(3)(F(6)acac)(3)]·4MeOH·2.5H(2)O, displays a large magnetocaloric effect, whose largest −ΔS(m) value is 21.88 J kg(–1) K(–1) (when T = 2 K and ΔH = 5 T); it thus can be utilized as a good magnetic refrigeration molecular material.