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Although progress has been made in the design and synthesis of chiral lanthanide clusters with pleasing structural connections and special shapes, assembly rules that guide their directional construction are still lacking. We reacted R/S -mandelic acid hydrazide, 2,3-dihydroxybenzaldehyde and DyCl3·6H2O under solvothermal conditions to obtain two octanuclear chirality clusters R-1 and S-1 , which are the enantiomers of each other. R/S -mandelic acid hydrazide and 2,3-dihydroxybenzaldehyde underwent an in situ reaction under "one-pot" conditions to generate a monohydrazone-type organic ligand R/S -mandelic acid hydrazide-2,3-dihydroxybenzaldehyde hydrazone (R/S -H2L). Four R/S -H2L ligands captured eight metal-centered Dy(III) ions and presented an annular arrangement, which assembled to form a pinwheel-shaped chiral cluster R/S-1. The benzene rings at the four vertices of R/S-1 can rotate freely as rotors. This is the first discovery of an annular growth mechanism during the self-assembly of lanthanide clusters. By changing the metal salt to Dy(NO3)3·6H2O, two twist-shaped hexanuclear clusters R-2 and S-2 , which are the enantiomers of each other were obtained. Four R/S -H2L and two R/S -H3L ligands captured six metal-centered Dy(III) ions, respectively, and were assembled through a linear growth mechanism to form the twist-shaped chiral clusters R/S-2. This is the first time that a linear growth mechanism has been proposed for the directional construction of lanthanide clusters with specific shapes. Circular dichroism results showed that R/S-1 and R/S-2 were both chiral clusters and enantiomers of each other. Magnetic studies showed that both R/S-1 and R/S-2 exhibit obvious single-molecule magnet (SMM) behaviors under zero-field conditions. This work is the first to propose an annular/linear growth mechanism for the design and synthesis of lanthanide clusters and allows the directional construction of chiral lanthanide clusters with special shapes and structural connections. [ABSTRACT FROM AUTHOR]

In the past two decades, tremendous progress has been made in the field of single-molecule magnets (SMMs), which not only achieves breakthroughs in various key indicators (flipping energy barrier and hysteresis temperature), but also expands SMMs of various types (3d, 4f, 3d–4f and 5f) and different connection methods. Among the many different types of SMM mentioned above, the SMM based on the 4f metal center has made the biggest breakthrough. Introducing 3d metal ions into lanthanide complexes to form 3d–4f heterometallic complexes can promote strong magnetic exchange between multiple metal centers, resulting in magnetic properties different from 3d and 4f complexes. Therefore, the expansion of the structure and magnetic properties of 3d–4f heterometallic complexes can promote the progress in the field of SMM. In this review, we summarize the structure and magnetic properties of 3d–4f heterometallic complexes formed by different types of organic ligands. [ABSTRACT FROM AUTHOR]

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]

We aim to analyze in detail the differences in SAM of lanthanide clusters driven by LCH, AT, and MCC methods. It highlights the great potential of MCC method in studying the SAM of lanthanide clusters. [Display omitted] • We summarize the structures of HNLCs constructed by the LCH and AT method. • We aim to analyze in detail the differences in self-assembly mechanisms driven by LCH, AT, and MCC method. • It highlights the great potential of MCC in studying the self-assembly mechanism of lanthanide clusters. • The structure design and synthesis of LCs are summarized and described from the perspective of assembly mechanism. The design and synthesis of lanthanide clusters with novel topological connections and desirable properties are attracting extensive attention. Researchers have obtained numerous types of lanthanide clusters (e.g. , tubular, cage, hamburger, and wheel) and examined their magnetocaloric effect, proton conductivity, sensing ability, applicability to lighting, and molecular magnetism. Despite substantial progress, lanthanide clusters are still primarily designed and synthesized via two common strategies: the ligand-controlled hydrolysis method and the anion-template method supported by carboxylic acid ligands. A detailed analysis of the formation and assembly mechanism would enable precisely controlled synthesis and the rapid development of crystal engineering. However, tracking the assembly process is difficult because both common strategies involve complex reactions with unstable intermediate and final products. Therefore, new guiding strategies for the design and construction of lanthanide clusters are urgently demanded. Bulky multidentate chelating ligands can quickly capture Ln(III) ions in solution, forming relatively stable single-template primitives. In the presence of an anion or specific hydrolyzate, single-template primitives assemble into multicomponent template primitives and then into complex lanthanide clusters (LCs). The intermediate template primitives are stable because the outer chelating ligands tightly wrap the inner metal center; consequently, the obtained LCs are highly stable in solution. These stable template primitives enable the identification of intermediates in the self-assembly process and facilitate the rational design and directed construction of LCs. In addition, the rapid capture of Ln(III) ions by multidentate chelating ligands greatly simplifies the self-assembly process, avoiding the formation of many low-stability, difficult-to-discriminate, chaotic, extremely complex, and diverse Ln(III)-ion hydrolysis intermediates and thereby promoting in-depth analysis of the self-assembly mechanisms (SAMs) of LCs. In recent years, multidentate chelate coordination (MCC) has emerged as a promising method for constructing serial LCs with decipherable SAMs. This review highlights the research progress on SAMs of LCs, focusing on the different SAMs of the hydrolysis method, anion-template method, and MCC method. The review highlights that MCC can advance SAM studies of LCs. [ABSTRACT FROM AUTHOR]