Nanosized Chiral [Mn₆Ln₂] Clusters Modeled by Enantiomeric Schiff Base Derivatives: Synthesis, Crystal Structures, and Magnetic Properties

Two enantiomeric pairs of new 3d–4f heterometallic clusters have been built from two enantiomer Schiff base derivatives, labeled as R-/S-H₂L, in situ obtained from the condensation reactions with o-vanillin and R-/S-2-phenylglycinol. The formulas of the series clusters are [Mn₆Ln₂­(μ₃-OH)₄­(μ₄-O)­(Ac)₄­(H₂O)₂­(R-L)₆]·NO₃·OH (Ln = Dy (1R), Gd (2R)), [Mn₆Ln₂­(μ₃-OH)₄­(μ₄-O)­(Ac)₄­(H₂O)₂­(S-L)₆]·NO₃·OH (Ln = Dy (1S), Gd (2S)), whose crystal structures and magnetic properties have been characterized. Structural analysis indicated that the above clusters consisted of a [Mn₆Ln₂] core, featuring a sandwich configuration. The results of magnetic measurements showed the presence of slow magnetic relaxation with the effective energy barrier of 14.85 K in two Dy derivatives under the condition of zero-dc field, while the significant magnetocaloric effect of Gd analogues was found in a wide temperature range.