Regulating the slow magnetic relaxation behavior of two different shapes Dy4 clusters with in situ formed penta‐ and heptadentate Schiff base ligands.

The design and synthesis of clusters possessing the same number of cores but different connection methods and properties have always been difficult. Herein, we used 2‐pyridinaldehyde, 1,3‐diamino‐2‐propanol, and Dy (ClO4)3·6H2O at room temperature (RT) to obtain the cluster [Dy4(L1)4(μ2‐OH)4]·4ClO4− (1, HL1 = 2‐pyridinecarboxaldehyde‐1,3‐diamino‐2‐propanol) with square Dy4O8 cluster cores. Cluster 1 consisted of four Schiff base ligands (L1)−, four Dy(III) ions, four bridged (μ2‐OH)−, and four free ClO4−. The ligand HL1 was formed by in situ Schiff base reaction with 2‐pyridinecarbaldehyde and 1,3‐diamino‐2‐propanol in the presence of Dy(III) ions. 2‐Aldehyde‐8‐hydroxyquinoline, 1,3‐diamino‐2‐propanol, and Dy (NO3)3·6H2O reacted at RT to yield a tetranuclear Dy(III) cluster [Dy4(L2)2(μ3‐OH)2(NO3)4(EtOH)2]·2CH3CN (2, H3L2 = 2‐aldehyde‐8‐hydroxyquinoline‐1,3‐diamino‐2‐propanol) with butterfly‐shaped Dy4O6 cluster core. Cluster 2 consisted of two ligands (L2)3−, four Dy(III) ions, two bridged μ3‐OH, two end‐group‐coordinated ethanol molecules, and four bidentate‐chelated NO3−. The in situ reaction of 2‐aldehyde‐8‐hydroxyquinoline and 1,3‐diamino‐2‐propanol under Dy(III) ion‐assisted catalytic conditions provided the ligand H3L2. It is worth noting that the magnetic test showed that 1 is a typical single‐molecule magnet (SMM), whereas 2 only showed a significant frequency dependence behavior. We considered Orbach and Raman processes (τ−1 = τ0−1 exp(−Ueff/kBT) + CTn) to fit 1 and 2 in the high‐temperature range and obtained Ueff = 7.01 and 5.43 K and τ0 = 1.18 × 10−4 and 4.14 × 10−5 s, respectively. [ABSTRACT FROM AUTHOR]