In Situ ReactionForms Uniform Mixed HeterometallicLn^III₂Mn^II₄ (Ln = Dy^III and Gd^III) Clusters: Assembly Mechanism andInsights into Performance

The unclear assembly mechanism seriously hinders the preparation and application of 3d–4f heterometallic clusters. Two new heterometallic nanoclusters [Dy₂Mn₄(HL)₄(OAc)₆]·5EtOH·H₂O (<b>1</b>) and [Gd₂Mn₄(HL)₄(OAc)₆]·4EtOH·4H₂O (<b>2</b>) were obtained from the in situ condensation reaction of 3-amino-1,2-propanediol with 2-hydroxy-1-naphthaldehyde. The intermediate species in the cluster <b>1</b> synthesis process were tracked by time-dependent high-resolution electrospray ionization mass spectrometry (HRESI-MS), further revealing the possible formation mechanism (Dy → DyL₂ →DyMn₂L₂ → DyMn₃L₂ → DyMn₄L₃ → Dy₂Mn₄L₄). Magnetic studies indicated that the antiferromagnet Ln^III–Mn^II (Ln = Dy^III and Gd^III) interaction was operative in both titled clusters. Furthermore, the performance of the clusters was regulated by adjusting the type of rare earth ions (Dy^III and Gd^III). The research results showed that cluster <b>2</b> containing Gd^III exhibited an excellent longitudinal relaxation rate (<i>r</i>₁) with 1.95 mM^–1 s^–1 under 0.5 T and a relatively suitable <i>r</i>₂/<i>r</i>₁ value (3.88), which indicated that it can be used as a new and efficient <i>T</i>₁ MR contrast agent. Cluster <b>1</b> containing Dy^III displayed antipathogenic activities against clinical MRSA strain with an MIC of 32 μg/mL. This work not only provided a reference for revealing the assembly mechanism of 3d–4f heterometallic clusters but also confirmed its potential application in the biomedical field.