Dysprosium Cluster Research Articles

Two dysprosium single molecule magnets with planar skeleton built from edge-shared Dy3 triangles

Two dysprosium clusters [Dy4(µ3-OH)2(L1)6(L2)2]·2CH3CN (1) and [Dy6(µ3-OH)2(L3)2(HL3)2(H2L3)2(EtOH)2Cl2]Cl2·2EtOH·4CH3CN (2) bearing in-situ formed Schiff base ligands (H2L2 and H3L3) were obtained from the solvothermal reactions of Dy(NO3)3∙5H2O with 8-hydroxyquinoline-2-carboxaldehyde and anthranilic acid (HL1), and DyCl3∙6H2O with 5-bromo-2-hydroxybenzaldehyde and 2-methyl-2-amino-1,3-propanediol, respectively. They present planar tetranuclear and hexanuclear skeletons constructed from two and four edge-shared triangular Dy3 units for 1 and 2, respectively. Magnetic tests showed that both titled dysprosium clusters are field-induced single molecule magnets. Ab initio calculations were also performed to interpret their SMM performances. Single molecule magnets bearing such planar skeletons are rarely reported.

Different anion (NO3- and OAc-)-controlled construction of dysprosium clusters with different shapes.

The complex hydrolysis process and strong uncertainty of self-assembly rules have led to the precise synthesis of lanthanide clusters still being in the "blind-box" stage and simplifying the self-assembly process and developing reliable regulation strategies have attracted widespread attention. Herein, different anions are used to induce the construction of a series of dysprosium clusters with different shapes and connections. When the selected anion is NO3-, it blocks the coordination of metal sites around the cluster through the terminal group coordination mode, thereby controlling the growth of the cluster. When NO3- was changed to OAc-, OAc- adopted a bridging mode to induce modular units to build dysprosium clusters through an annular growth mechanism. Specifically, we selected 2-amino-6-methoxybenzoic acid, 2-hydroxybenzaldehyde, and Dy(NO3)3·6H2O to react under solvothermal conditions to obtain a pentanuclear dysprosium cluster (1). The five Dy(III) ions in 1 are distributed in upper and lower planes and are formed by the tight connection of nitrogen and oxygen atoms, and μ3-OH- bridges on the ligand. Next, octa-nuclear dysprosium cluster (2) were obtained by only regulating ligand substituents. The eight Dy(III) ions in 2 are tightly connected through ligand oxygen atoms, μ2-OH-, and μ3-OH- bridges, forming an elliptical {Dy/O} cluster core. Furthermore, only by changing NO3- to OAc-, a wheel-shaped tetradeca-nuclear dysprosium cluster (3) was obtained. Cluster 3 is composed of OAc- bridged multiple template Dy3L3 units and pulling of these template units connected by an annular growth mechanism forms a wheel-shaped cluster. The angle of the coordination site on NO3- is ∠ONO = 115°, which leads to the further extension of the metal sites on the periphery of clusters 1 and 2 through the terminal group coordination mode, thereby regulating the structural connection of the clusters. However, the angle of the coordination site on OAc- is ∠OCO = 128°, and a slightly increased angle leads to the formation of a ring-shaped cluster 3 by connecting the template units through bridging. This is a rare example of the controllable construction of lanthanide clusters with different shapes induced by the regulation of different anions, which provides a new method for the precise construction of lanthanide clusters with special shapes.

Unusual magnetic relaxation in a single-molecule magnet with toroidal magnetic moments

We report the synthesis and characterization of a single-molecule magnet composed of triangular clusters of dysprosium ions. The structural study shows that the symmetry changes from one polar point group (mm2) at room temperature to another polar point group (m) at low temperature. Magnetic studies and theory calculations illustrate that the vortex distribution of magnetic dipoles in the triangular dysprosium clusters forms a toroidal magnetic moment. Interestingly, the analysis of AC magnetic susceptibility reveals the coexistence of three distinct magnetic relaxation processes, corresponding to the Raman, Orbach, and QTM relaxation pathways, respectively. The sum of three modified Debye functions is successfully used to describe the multiple relaxation behavior.

Double butterfly-shaped octanuclear dysprosium clusters: structure, magnetism and assembly mechanism

This is the first time to explore the self-assembly process of double butterfly-shaped lanthanide high-nucleus clusters and propose their possible assembly mechanism.

Anion-Manipulated Hydrolysis Process Assembles of Giant High-Nucleation Lanthanide-Oxo Cluster.

Widespread concern has been raised over the synthesis of highly nucleated lanthanide clusters with special shapes and/or specific linkages. Construction of lanthanide clusters with specific shapes and/or linkages can be achieved by carefully regulating the hydrolysis of lanthanide metal ions and the resulting hydrolysis products. However, studies on the manipulation of lanthanide-ion hydrolysis to obtain giant lanthanide-oxo clusters have been few. In this study, we obtained a tetraicosa lanthanide cluster (3) by manipulating the hydrolysis of Dy(III) ions using an anion (OAc-). As far as we know, cluster 3 has the highest nucleation among all lanthanide-oxo clusters reported. In 3, two triangular Dy3O4 are oriented in opposite directions to form the central connecting axis Dy6(OH)8, which is in turn connected to six Dy3O4 that are oriented in different directions. Meanwhile, a sample of a chiral trinuclear dysprosium cluster (1) was obtained in a mixed CH3OH and CH3CN solvent and by replacing the anion in the reaction to Cl- ions. In this cluster, 1,3,4-thiadiazole-2,5-diamine (L2) is free on one side through π···π interactions and is parallel to the o-vanillin (L1)- ligand, thus resulting in a triangular arrangement. The arrangement of L2 affects the end group coordination in the cluster 1 structure through hydrogen bonding and induces the cluster to exhibit chirality. When the reaction solvent was changed to CH3OH, a sample of cluster 2, composed of two independent triangular Dy3 that have different end group arrangements, was obtained. Magnetic analysis showed that clusters 1 and 3 both exhibit distinctive single-molecule magnetic properties under zero-magnetic-field conditions. This study thus provides a method for the creation of chiral high-nucleation clusters from achiral ligands and potentially paves the way for the synthesis of high-nucleation lanthanide clusters with unique forms.

Giant Crown-Shaped Dy34 Nanocluster with High Acid-Base Stability Assembled by an out-to-in Growth Mechanism.

Lanthanoid metal ions have large ionic radii, complex coordination modes, and easy distortion of coordination spheres, but the design and synthesis of high-nucleation lanthanoid clusters with high stability in solution (especially aqueous solution) are challenging. Herein, a diacylhydrazone ligand (H2L1) with multidentate chelating coordination sites was used to react with Dy(OAc)3·4H2O under solvothermal conditions to obtain an example of a 34-nucleus crown-shaped dysprosium cluster [Dy34(L)8(μ2-OH)(μ3-OH)21(μ3-O)14(OAc)31(OCH3)2(H2O)15](OAc)3 (1). Structural analysis showed that the bisacylhydrazone ligand H2L1 with polydentate chelate coordination sites could rapidly capture DyIII ions, thereby forming 34-nucleus crown-shaped dysprosium cluster 1 following the out-to-in growth mechanism. Cluster 1 remained stable after immersion in solutions with different pH values (3-14) for 24 h. To the best of the authors' knowledge, high-nucleation lanthanoid clusters with excellent strong acid and base stability and water stability are very rare. Meanwhile, high-resolution electrospray mass spectrometry molecular ion peaks produced by cluster 1 were captured, which proved to be stable also in organic solvents. Magnetic research showed that cluster 1 exhibited frequency-dependent behavior. This work provides a new idea for designing and synthesizing high-nucleation lanthanoid clusters with high stability.

Synthesis and structures of fluoride-bridged dysprosium clusters: influence of fluoride ions on magnetic relaxation behaviors

The synthesis of fluoride-bridged 1Dy, 2Dy and hepta-nuclear 3Dy dysprosium complexes is reported here and a hydroxy-bridged dinuclear dysprosium complex 4Dy is synthesized for comparison.

Truncation reaction regulates the out-to-in growth mechanism to decrypt the formation of brucite-like dysprosium clusters.

Specially shaped high-nuclear lanthanide cluster assembly has attracted widespread attention, but the study of their self-assembly mechanism is still stagnant. Herein, we used a polydentate chelating bis-acylhydrazone ligand to construct a rare 16-nuclear dysprosium cluster 1 with a brucite-like structure. The capture agents, pivalic acid and di(pyridin-2-yl)methanone, were added into the reaction system, and the hexanuclear dysprosium cluster 2 and heptanuclear dysprosium cluster 3 were obtained, respectively. Clusters 2 and 3 support the out-to-in growth mechanism as key evidence. To the best of our knowledge, this study is the first to use truncation reaction to decipher the formation mechanism of high-nuclear lanthanide clusters.

Anion and Solvent Manipulated Out-to-In Growth Mechanism to Assemble a Series of Different Dysprosium Clusters

Abstract Although various lanthanide clusters with different shapes and connections have been synthesised, more rules are still needed to guide their further serial expansion and directed structural modification. Herein, we used the multidentate chelating ligand N′2,N′9-bis((E)-2-hydroxy-3-methoxybenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide (H4L) to react with Dy(NO3)3·6H2O under EtOH/CH3CN conditions to obtain an example of a nonanuclear dysprosium cluster, i.e., [Dy9(L)2(μ2-OH)(μ3-OH)6(NO3)12(H2O)3]·5CH3CN·H2O (1). The structural framework of cluster 1 contains 2 (L)4− ligands, 1 μ2-OH−, 6 μ3-OH−, 12 NO3−, and 3 H2O. Each ligand (L)4− chelates five Dy(III) ions, and its coordination mode is μ5-η1:η2:η1:η2:η1:η1:η2:η1:η2:η1. Cluster 1 has many different connection modes of NO3−, such as μ5-η2:η2:η2, μ2-η1:η1, and μ2-η1:η2. Notably, we only changed the metal salt to Dy(OAc)3·6H2O and obtained an example of a trinuclear dysprosium cluster, i.e., [Dy3(H2L)(OAc)7]·CH3CN·3H2O (2). The structure of cluster 2 contains three Dy(III) ions, one (H2L)2− ion, one μ3-η2:η2-bridged OAc− and six end-coordinated OAc−. The coordination mode of ligand (H2L)2− is μ3-η1:η1:η2:η1:η1:η1:η2:η1. More notably, we only changed the solvent to MeOH/CH3CN, and under the same reaction conditions, we got an example of a dodeca-nucleus dysprosium cluster, i.e., [Dy12(L)4(μ2-OH)2(OAc)14(H2O)8]·4C2H3O2·2H2O (3). In cluster 3, ligand (L)4− adopts the μ5-η1:η2:η1:η2:η1:η1:η2:η1:η2:η1 coordination mode, and the four ligands (L)4− are connected to each other forming the grid structure. Twelve Dy(III) ions are “embedded” in the chelating sites of the ligand and bridged by multiple OAc− ions. A large cavity is formed in the centre of the ‘well’ in cluster 3. The test results of variable temperature AC magnetic susceptibility show that clusters 1–3 all exhibit single-molecule magnet behaviour. To the best of our knowledge, this study is the first to describe that an out-to-in growth mechanism has been manipulated by anions and solvents to realise the synthesis of a series of completely differently connected dysprosium clusters. In addition, this mechanism is also one of the rare examples of anion and solvent co-induced assembly to form lanthanide clusters with completely different shapes and connections.

A series of dysprosium clusters assembled by a substitution effect-driven out-to-in growth mechanism

The diacylhydrazone ligands with different substituents were reacted with Dy(NO3)3·6H2O to obtain 16 nuclear (1) and 10 nuclear (2) and pentanuclear (3) dysprosium clusters. Clusters 1–3 are gradually formed through out-to-in growth mechanism.

Modulating the relaxation dynamics via structural transition from a dinuclear dysprosium cluster to a nonanuclear cluster.

A dinuclear dysprosium cluster [Dy2(NO3)4(H2O)2(L)2]·2CH3CN was successfully prepared by employing HL (HL = 2,6-dimethoxyphenol) and Dy(NO3)3·6H2O in a mixture of CH3OH and CH3CN. The conversion of this Dy2 compound by reaction with additional deprotonated ligand generated a Dy9 cluster [Dy9(μ4-OH)2(μ3-OH)8(μ2-OCH3)4(NO3)8(H2O)8(L)4](OH)·2H2O with the well-known "diabolo" topology. Magnetic investigation revealed that both of the clusters exhibit typical SMM characteristics, and variable magnetic relaxation with the energy barrier changing from 217.87 K to 9.24 K along with the transition from a dinuclear dysprosium cluster to a nonanuclear one. Ab initio calculations further confirm the corresponding structure-activity relationships that originate the different magnetic behaviours. This design may afford a feasible strategy for modulating the magnetic relaxation dynamics of polynuclear systems.

PH manipulates the assembly of a series of dysprosium clusters with subtle differences

This study is the first to fine-tune a series of lanthanide clusters with the same shape through pH manipulation.

Assembly of Dy60 and Dy30 cage-shaped nanoclusters

Rapid kinetics, complex and diverse reaction intermediates, and difficult screening make the study of assembly mechanisms of high-nuclearity lanthanide clusters challenging. Here, we synthesize a double-cage dysprosium cluster [Dy60(H2L1)24(OAc)71(O)5(OH)3(H2O)27]·6H2O·6CH3OH·7CH3CN (Dy60) by using a multidentate chelate-coordinated diacylhydrazone ligand. Two Dy30 cages are included in the Dy60 structure, which are connected via an OAc− moiety. The core of Dy60 is composed of 8 triangular Dy3 and 12-fold linear Dy3 units. We further change the alkali added in the reaction system and successfully obtain a single cage-shaped cluster [Dy30(H2L1)12(OAc)36(OH)4(H2O)12]·2OH·10H2O·12CH3OH·13CH3CN (Dy30) with a perfect spherical cavity, which could be considered an intermediate in Dy60 formation. Time-dependent, high-resolution electrospray ionization mass spectrometry (HRESI-MS) is used to track the formation of Dy60. A possible self-assembly mechanism is proposed. We track the formation of Dy30 and the six intermediate fragments are screened.

A novel [formula omitted] cluster constructed by a multidentate 8-hydroxyquinoline Schiff base ligand: Structure and slow magnetic relaxation behavior

A new tetranuclear Dy(III)-based complex, namely, [Dy4(TTA)4L4(H2O)2]·4CH3OH (1) (H2L = 2-[(4-methoxy-phenyl)imino]methyl]-8-hydroxy- quinoline, TTA = 2-thenoyltrifluoroacetone), has been obtaied by using a multidentate 8-hydroxyquinoline Schiff base ligand (H2L). The structure and magnetic property of cluster 1 have been completely characterized. The structural study reveals that cluster 1 is a tetranuclear dysprosium cluster, in which four Dy(III) ions are conected by four μ-O atoms and two carboxyl of four H2L ligands forming a parallelogram. Magnetic studies reveal that cluster 1 shows slow magnetic relaxation behavior.

A New Planar Hexanuclear Dysprosium Cluster Exhibiting Slow Magnetic Relaxation Features

Reaction of the Schiff base ligand H2L and dysprosium acetate result in a new planar Dy6 cluster [Dy6(μ3‐OH)L6(Ac)6]·MeOH (1) [H2L = N'‐(2‐hydroxybenzylidene)‐2‐(hydroxyimino)propanohydrazide, HAc = acetic acid], which was successfully structurally and magnetically characterized. Single‐crystal X‐ray diffraction analysis revealed that 1 contained a hexanuclear dysprosium cluster [Dy6], which is composed of four Dy3 triangular units. Magnetic measurements suggest that 1 displays single‐molecule magnet (SMM) behavior which is enhanced by applying a 4000 Oe direct‐current field. The effective anisotropic barrier Ueff/kB = 14.9 K and the pre‐exponential factor τ0 = 1.31 × 10–6 s are also obtained. This work may provide more insights for the design and investigation of lanthanide‐based SMMs.

Solvent-driven structures and slow magnetic relaxation behaviors of dinuclear dysprosium clusters

Three dinuclear dysprosium compounds, [Dy2(dbm)2(L)2(H2O)2]·CH3CN (1), [Dy2(dbm)3(L)(HL)(CH3OH)]·CH3OH (2) and [Dy2(dbm)2(L)2(C2H5OH)2] (3) (H2L = N′-(2-hydroxybenzylidene)-2-(hydroxyimino)-propanohydrazide, Hdbm = 1,3-diphenyl-1,3-propanedione), were successfully synthesized by controlling the reaction solvents. Single-crystal X-ray diffraction analysis reveal that 1–3 all possess [Dy2O2] core, whereas their coordination solvents are different with two coordinated water molecules for 1, one coordinated methanol molecule for 2 and two coordinated ethanol molecules for 3. All the eight-coordinated Dy(III) ions of 1–3 are located in a distorted bicapped trigonal-prismatic (BCTP) geometry. Interestingly, magnetic investigation reveal that compounds 1–3 exhibit distinct slow magnetic relaxation behaviors with the energy barrier (2.29 ± 1.17) K for 1, (1.31 ± 1.05) K for 2 and (45.61 ± 3.24) K for 3. This work provides a promising strategy for the construction and regulation of lanthanide single-molecule magnetisms.

Tracking the Stepwise Formation of the Dysprosium Cluster (Dy10) with Multiple Relaxation Behavior.

High-nuclear lanthanide clusters are generally formed by the rapid accumulation of simple building units. Thus, tracking and observing the stepwise assembly process, which is vital for understanding the assembly mechanism, are extremely difficult. Herein, the decanuclear nanocluster [Dy10(L1)6(μ5-NO3)2(OAc)10(HOAc)2]·8H2O (Dy10, H3L1 = (E)-3-((3-ethoxy-2-hydroxybenzylidene)amino)propane-1,2-diol) was obtained from the reaction of Dy(NO3)3·6H2O, Dy(OAc)3·6H2O, 3-ethoxy-2-hydroxybenzaldehyde (L2), and 3-amino-1,2-propanediol (L3). The reaction process was further tracked by time-dependent high-resolution electrospray ionization mass spectrometry, and seven reaction intermediate fragments were screened. A stepwise assembly mechanism was observed based on these fragments, that is, L → Dy1 → Dy2 → Dy3 → Dy4 → Dy5 → Dy6 → Dy10. This study is the first to discover a stepwise assembly mechanism during the formation of high-nuclear lanthanide clusters (cluster nucleus > 3). Magnetic studies have shown the multiple relaxation behavior of Dy10.

Syntheses, structure and single-molecule magnet behavior of a rhombus shaped Dy4 cluster

A new Dy4 cluster, namely, Dy4(acac)4L6(μ3-OH)2·4CH3CN (1) (HL = 5-(2-hydroxy-5-methylbenzylidene)-8-hydroxylquinoline, acac = acetylacetonate), has been synthesized based on a bidentate Schiff base ligand. Furthermore, elemental analysis (EA), powder X-ray diffraction (PXRD), single-crystal X-ray diffraction and magnetic properties of cluster 1 have been characterized. The X-ray structural analysis exhibits that cluster 1 is a tetranuclear dysprosium cluster with rhombus-shaped arrangement, and each Dy(III) ion of 1 is eight coordinated, and their coordination polyhedrons can be described as a distorted square-antiprismatic geometry. Magnetic properties measurement indicate that two magnetic relaxation processes phenomenon occurs for cluster 1 under 0 dc filed, with pre-exponential factor τ0 = 8.19 × 10−7 s and ΔE/kB = 37.73 K for the LT relaxation and τ0 = 4.36 × 10−8 s and ΔE/kB = 105.97 K for the HT relaxation.

Coupling Dy3 triangles into hexanuclear dysprosium(III) clusters: Syntheses, structures and magnetic properties

Structural modifications in two novel Dy6 clusters, [Dy6(μ3-OH)4(μ2-OH)2(L1)8(H2O)6](CF3SO3)4·6H2O (1) and [Dy6Na2(L2)4(O2)(PhCOO)10(H2O)2] (2), enhances their single-molecule magnet (SMM) performance. Of particular interest is that these two compounds exhibit analogous Dy6 cores via coupling Dy3 units and possess identical coordination geometries with different distortions. Alternating-current magnetic susceptibility measurements revealed that compound 1 displayed obvious SMM behavior under a zero applied direct current (dc) field. Fitting the magnetic data of compound 1 gives an effective energy barrier to magnetization reversal, Ueff, of 19.8 K, whereas only slow relaxation is observed for compound 2. This significant discrepancy is mainly due to the extremely distorted coordination geometries of the DyIII ions for compound 2, which introduce stronger quantum tunneling of magnetization (QTM). Furthermore, the anisotropy axes of compound 1 were arranged similar to a parallelogram.

Pico-level DNA sensing by hetero-polymetalate, Na10{Dy2W10O30(µ-S)6}·80H2O, cluster

The polyoxometalate dysprosium cluster, (Dy–S–W POM) , Na10[Dy2W10O30(µ-S)6]·80H2O, shows remarkable dsDNA denaturation property. In the presence of 0.22 µmol of this Dy–S–W POM, the melting temperature (Tm) of calf-thymus (CT) dsDNA is decreased to 62.35 °C. Dy–S–W POM shows bleaching of methylene blue (MB). Addition of CT-DNA in the MB bleached solution of Dy–S–W POM apparently intercalates MB. Such trapped MB by CT-DNA responds to its re-oxidation by elemental sulfur formed in the bleaching process involving Dy–S–W POM. This reduction–oxidation property of MB with Dy–S–W POM led to the detection of pico (13.20 pmol) level of DNA even by naked eye, which will be helpful for rapid trace DNA detection in forensic science and DNA-related diagnostics, complimenting time-consuming sophisticated methodology.