Chiral Star-Shaped [Co^III₃Ln^III] Clusters with Enantiopure Schiff Bases: Synthesis, Structure, and Magnetism

Two enantiomeric pairs of new 3d–4f heterometallic clusters have been synthesized from two enantiomer Schiff base derivatives: (R/S)-2-[(2-hydroxy-1-phenylethylimino)methyl] phenol (R-/S-H₂L). The formulae of the series clusters are Co₃Ln(R-L)₆ (Ln = Dy (1R), Gd (2R)), Co₃Ln (S-L)₆ (Ln = Dy (1S), Gd (2S)), whose crystal structures and magnetic properties have been characterized. Structural analysis indicated that the above clusters crystallize in the chiral P2₁3 group space. The central lanthanide ion has a coordination geometry of D₃ surrounded by three [Co^III(L)₂]^– anions using six aliphatic oxygen atoms of L²⁻ featuring a star-shaped [Co^III₃Ln^III] configuration. Magnetic measurements showed the presence of slow magnetic relaxation with an effective energy barrier of 22.33 K in the Dy^III derivatives under a zero-dc field. Furthermore, the circular dichroism (CD) spectra of 1R and 1S confirmed their enantiomeric nature.