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.