A trinuclear dysprosium mononuclear magnet based on acylhydrazone schiff base and a preparation method thereof

Abstract

The application relates to the technical field of new rare earth-based magnetic materials, in particular to a trinuclear dysprosium monomolecular magnet based on acylhydrazone Schiff base and a preparation method, which has a chemical formula of {[Dy3L2(CH3OH)4(H2O)4]·Cl}, wherein L is an acylhydrazone Schiff base ligand; the chemical composition of the magnet Dy3L2 comprises three Dy Ⅲ ions, two partially deprotonated acylhydrazone Schiff base ligands, and the acylhydrazone Schiff base ligand has a molecular structural formula of: the acylhydrazone Schiff base ligand has suitable coordination ability and a spatial configuration, can form a stable coordination bond with a rare earth ion, and the Dy 3+ ion coordinated with the acylhydrazone Schiff base ligand has the characteristics of large magnetic anisotropy, large magnetic moment, weak crystal field splitting and strong spin-orbit coupling, and the combination of the two can synthesize a high-efficiency monomolecular magnet. The special coordination configuration of the ligand and the Dy 3+ ion solves the problem of poor relative stability and controllability of the monomolecular magnet in the prior art due to small single-ion magnetic anisotropy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new rare earth-based magnetic materials, in particular to a trinuclear dysprosium single-molecule magnet based on acylhydrazone Schiff base and a preparation method thereof. BACKGROUND

[0002] Magnetic materials play a prominent role in people's daily life, from information storage technology to communication device technology to medical device technology, and they are ubiquitous and play an important role. Single-molecule magnets (SMMs) are complexes that have potential applications in high-density information storage, spintronics, quantum computing, and magnetic cooling. These fascinating complexes work due to significant magnetic anisotropy, which introduces an energy barrier to the randomization of the direction of the molecular magnetic moment.

[0003] Rare earth elements have an unfilled 4f electron structure, and their f electrons have strong spin-orbit coupling and large unquenched orbital angular momentum, so rare earth ions have large spin ground states and magnetic anisotropy. Rare earth element single-molecule magnets are a new type of magnetic material, and their main components are rare earth elements and metal elements, and the magnetism is mainly generated by single ions of rare earth elements. Such magnets have excellent properties such as high magnetic moment and high magnetostriction, and therefore have wide application prospects in the fields of magnetic materials, nanotechnology, and magnetic storage.

[0004] However, the magnetism of rare earth single-molecule magnets is mainly due to single-ion magnetic anisotropy, and because the single-ion magnetic anisotropy is small, the relative stability and controllability are poor, thereby limiting the development of rare earth single-molecule magnets. SUMMARY

[0005] In view of the problem in the prior art that single-molecule magnets have poor relative stability and controllability due to small single-ion magnetic anisotropy, the present application provides a trinuclear dysprosium single-molecule magnet based on acylhydrazone Schiff base and a preparation method thereof.

[0006] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0007] The present application provides a trinuclear dysprosium single-molecule magnet based on acylhydrazone Schiff base,

[0008] The chemical formula is {[Dy3L2(CH3OH)4(H2O)4]·Cl};

[0009] The molecular structure formula is: L is an acylhydrazone Schiff base ligand.

[0010] Further, the molecular structure formula of the acylhydrazone Schiff base ligand is:

[0011] The preparation method of the tri-nuclear dysprosium monomolecular magnet based on acylhydrazone Schiff base as described above comprises the following steps:

[0012] The first heating reaction is performed on the methyl salicylate and the alcohol solution of hydrazine hydrate to obtain salicylic hydrazide;

[0013] The salicylic hydrazide and 3-amino-2-hydroxyacetophenone are dissolved in an alcohol solution and the second heating reaction is performed to obtain an intermediate W;

[0014] The third heating reaction is performed on the intermediate W and the alcohol solution of salicylaldehyde to obtain an acylhydrazone Schiff base ligand;

[0015] After the deprotonation treatment of the acylhydrazone Schiff base ligand, the dysprosium salt is added to perform a reaction to obtain the tri-nuclear dysprosium monomolecular magnet.

[0016] Further, the molar ratio of the methyl salicylate to the hydrazine hydrate is (1:1) to (1:1.2).

[0017] Further, the molar ratio of the salicylic hydrazide to the 3-amino-2-hydroxyacetophenone is (1:0.95) to (1:1.05).

[0018] Further, the molar ratio of the intermediate W to the salicylaldehyde is (1:0.95) to (1:1.05).

[0019] Further, the molar ratio of the acylhydrazone Schiff base ligand to the dysprosium salt is (1:1) to (1:2).

[0020] Further, the temperature of the first heating reaction, the second heating reaction and the third heating reaction is 55-80 DEG C and the reaction time is 6-12 hours.

[0021] Further, the dysprosium salt is DyCl3.6H2O and the reaction temperature is 15-35 DEG C.

[0022] A tri-nuclear dysprosium monomolecular magnet based on acylhydrazone Schiff base prepared by the above method, the monomolecular magnet is tetragonal system, the space group is P-421c; the cell parameters are as follows: α=90°, β=90°, γ=90°, Dc=1.233 g / cm 3 , Z=8, F(000)=5680.0, μ(MoKa)=2.874 mm -1 , GooF=1.070, crystal size: 0.17 mm x 0.13 mm x 0.12 mm, R1=0.0495, wR2=0.1254 [I>=2σ(I)].

[0023] Compared with the prior art, the present application has the following beneficial effects:

[0024] The application discloses a trinuclear dysprosium single-molecule magnet based on acylhydrazone Schiff base, and has a chemical formula of {[Dy3L2(CH3OH)4(H2O)4]·Cl}.

[0025] The molecular structural formula is shown in the following formula: In the formula, L represents an acylhydrazone Schiff base ligand. Ⅲ The chemical composition of the magnet Dy3L2 comprises three Dy ions, two partially deprotonated acylhydrazone Schiff base ligands, four methanol molecules for terminal coordination, four water molecules, and one free chloride ion. Ⅲ One of the Dy ions is coordinated with two N atoms and six O atoms to form an 8-coordination configuration, which is derived from four O atoms and two N atoms of the two ligands L after deprotonation, and two O atoms of two methanol molecules. Ⅲ The other two Dy ions are coordinated with one N atom and seven O atoms to form an 8-coordination configuration, which is derived from two O atoms and one N atom of one ligand L after deprotonation, and three O atoms of three methanol molecules and two O atoms of two water molecules. 3+ The acylhydrazone Schiff base ligand has suitable coordination ability and spatial configuration, and can form a stable coordination bond with the rare earth ion. 3 The Dy ions coordinated with the acylhydrazone Schiff base ligand have the characteristics of large magnetic anisotropy, large magnetic moment, weak crystal field splitting, and strong spin-orbit coupling, and are easy to synthesize high-efficiency single-molecule magnets.

[0026] The application further provides a preparation method of the trinuclear dysprosium single-molecule magnet based on the acylhydrazone Schiff base.

[0027] The trinuclear dysprosium single-molecule magnet based on the acylhydrazone Schiff base is prepared by the method, and has a tetragonal crystal system and a space group of P-421c. α=90°, β=90°, γ=90°, Dc=1.233 g / cm 3 Z=8, F(000)=5680.0, μ(MoKa)=2.874 mm -1GooF = 1.070, crystal size: 0.17 mm x 0.13 mm x 0.12 mm, R1 = 0.0495, wR2 = 0.1254 [I > 2sigma (I)]. The triangular Dy3 complex was synthesized, and the triangular Dy3 cluster is a unique prototypical system in single-molecule magnets, which has peculiar magnetic behavior. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a molecular structure model diagram of a trinuclear dysprosium single-molecule magnet based on acylhydrazone Schiff base according to the present application.

[0029] Figure 2 It is a preparation method flow chart of a trinuclear dysprosium single-molecule magnet based on acylhydrazone Schiff base according to the present application.

[0030] Figure 3 It is an infrared spectrum diagram of the acylhydrazone Schiff base ligand according to the present application.

[0031] Figure 4 It is an infrared spectrum diagram of the trinuclear dysprosium single-molecule magnet Dy3L2 prepared in Example 1 of the present application.

[0032] Figure 5 It is a variable-temperature magnetization graph of the trinuclear dysprosium single-molecule magnet Dy3L2 prepared in Example 1 of the present application, wherein a is χ M T value curve with temperature, b is χ M -1 curve with temperature.

[0033] Figure 6 It is a magnetization intensity curve graph of the trinuclear dysprosium single-molecule magnet Dy3L2 prepared in Example 1 of the present application at different temperatures.

[0034] Figure 7 It is an alternating current magnetization graph of the trinuclear dysprosium single-molecule magnet Dy3L2 prepared in Example 1 of the present application under a 500 Oe external field, wherein a is an alternating current magnetization real part χ' signal change curve graph, and b is an alternating current magnetization imaginary part χ" signal change curve graph.

[0035] Figure 8 It is a curve graph of the real part (χ') and the imaginary part (χ") of the alternating current magnetization of the trinuclear dysprosium single-molecule magnet Dy3L2 prepared in Example 1 of the present application with temperature change under a 500 Oe external field. DETAILED DESCRIPTION

[0036] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein are used in the sense commonly understood by one skilled in the art of the present application, and in the event of a conflict between the definitions of the specification and the definitions of the art, the definitions of the specification shall control.

[0037] Theories and mechanisms described and disclosed herein, whether correct or not, should not be construed as limiting the scope of the present application, which is defined only by the claims. The description herein can be implemented in the absence of any theory or mechanism.

[0038] Herein, all features defined by numerical ranges or percentage ranges, such as numerical values, amounts, contents and concentrations, are for the sake of brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0039] Herein, unless otherwise specified, "comprise", "include", "contain", "have" or similar words are intended to cover the meaning of "consist of" and "consist essentially of", for example, "A comprises a" covers the meaning of "A comprises a and other" and "A comprises only a".

[0040] Herein, for the sake of brevity, all possible combinations of the various technical features in the various embodiments or examples are not described. Therefore, the various technical features in the various embodiments or examples can be combined in any manner as long as there is no contradiction, and all possible combinations should be considered to be within the scope of the present specification.

[0041] The present application will be further described with reference to the following specific examples. It is to be understood that these examples are only used to illustrate the present application and not intended to limit the scope of the present application. Furthermore, it is to be understood that those skilled in the art can make various modifications or changes to the present application upon reading the content of the present application, and these equivalent forms should also fall within the scope of the claims attached herewith.

[0042] In the following examples, the instruments and apparatuses of the art are used. In the following examples, the experimental methods not otherwise specified are usually carried out according to the conventional conditions or according to the conditions suggested by the manufacturers. In the following examples, various raw materials are used, and unless otherwise specified, the conventional commercially available products are used, and the specifications are the conventional specifications in the art. In the specification of the present application and in the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0043] The application will be further described in detail below with reference to specific examples, which are intended to explain but not limit the application.

[0044] Referring to Figure 1 The application discloses a kind of based on acylhydrazone schiff base's trinuclear dysprosium single molecule magnet,

[0045] Chemical formula is: {[Dy3L2 (CH3OH) 4 (H2O) 4] · Cl};

[0046] Molecular structure formula is: Wherein, L is acylhydrazone schiff base ligand, the chemical composition of the magnet Dy3L2 includes 3 Dy Ⅲ Ion, 2 parts of deprotonated acylhydrazone schiff base ligand, the molecular structure formula of the acylhydrazone schiff base ligand is: Still structure includes 4 methanol molecules and 4 water molecules of terminal coordination, and 1 free chloride ion;One of the Dy Ⅲ Ion in the magnet is coordinated with 2 N atoms and 6 O atoms, forms 8 coordination configuration, which is respectively derived from 4 O atoms and 2 N atoms after 2 ligands L deprotonation, and 2 O atoms of 2 methanol molecules;The remaining two Dy Ⅲ Ion is coordinated with 1 N atom and 7 O atoms, forms 8 coordination configuration, which is respectively derived from 2 O atoms and 1 N atom after 1 ligand L deprotonation, and 3 O atoms of 3 methanol molecules and 2 O atoms of 2 water molecules. Among them, acylhydrazone schiff base ligand has suitable coordination ability and spatial configuration, can form stable coordination bond with rare earth ion, and the Dy 3+ Ion coordinated with it has the characteristics of large magnetic anisotropy, large magnetic moment, weak crystal field splitting, strong spin-orbit coupling, etc., and is easy to synthesize high-efficiency single molecule magnet.

[0047] Referring to Figure 2 The preparation method of the above-mentioned acylhydrazone schiff base-based trinuclear dysprosium single molecule magnet comprises the following steps:

[0048] S1: methyl salicylate and alcohol solution of hydrazine hydrate are subjected to first heating reaction to obtain salicylic hydrazine, specifically:

[0049] Methyl salicylate and hydrazine hydrate are dissolved in ethanol or methanol in a molar ratio of (1:1) to (1:1.2), and heated to reflux and stirred at 55 DEG C to 80 DEG C for 6 to 12 hours, and white solid powder is obtained by suction filtration, which is salicylic hydrazine, and the reaction formula is:

[0050] S2: salicylic hydrazine and 3-amino-2-hydroxyacetophenone are dissolved in alcohol solution and subjected to second heating reaction to obtain intermediate W, specifically:

[0051] The salicylic hydrazide and 3-amino-2-hydroxyacetophenone are dissolved in ethanol or methanol in a mass ratio of (1:0.95) to (1:1.05), heated and stirred under the condition of 55-80℃ for 6-12 hours, and then filtered to obtain yellow-green solid powder, which is the intermediate W, and the reaction formula is as follows:

[0052]

[0053] S3: The alcohol solution of the intermediate W and salicylaldehyde is subjected to a third heating reaction to obtain an acylhydrazone Schiff base ligand, and the specific process is as follows:

[0054] The intermediate W and salicylaldehyde are dissolved in methanol or ethanol in a mass ratio of (1:0.95) to (1:1.05), heated and stirred under the condition of 55-80℃ for 6-12 hours, and then filtered to obtain yellow solid powder, which is the acylhydrazone Schiff base ligand, and the reaction formula is as follows:

[0055]

[0056] S4: The acylhydrazone Schiff base ligand is subjected to deprotonation treatment and then reacted with dysprosium salt to obtain a trinuclear dysprosium single-molecule magnet, and the specific process is as follows:

[0057] The acylhydrazone Schiff base ligand is dispersed in methanol, subjected to deprotonation treatment, and then reacted with dysprosium salt to obtain a solution mixture system, the solution mixture system is filtered to obtain a filtrate, and the filtrate is dried to obtain a trinuclear dysprosium single-molecule magnet, wherein the mass ratio of the acylhydrazone Schiff base ligand to the dysprosium salt is (1:1) to (1:2), the dysprosium salt is DyCl3·6H2O, and the reaction temperature is 15-35℃.

[0058] Example 1

[0059] In an ethanol solution containing 0.05 mol of methyl salicylate, 0.05 mol of hydrazine hydrate is added, and the mixture is heated and stirred under reflux at 80℃ for 6 hours to obtain a white turbid solution, which is filtered to obtain salicylic hydrazide.

[0060] In an ethanol solution containing 0.046 mol of salicylic hydrazide, 0.046 mol of 3-amino-2-hydroxyacetophenone is added, and the mixture is heated and stirred under reflux at 70℃ for 12 hours to obtain a yellow-green turbid solution, which is filtered to obtain yellow-green powder intermediate W.

[0061] In an ethanol solution containing 0.02 mol of intermediate W, 0.02 mol of salicylaldehyde is added, and the mixture is heated and stirred under reflux at 80℃ for 12 hours to obtain a yellow turbid solution, which is filtered to obtain yellow powder acylhydrazone Schiff base ligand L.

[0062] Take 0.05mmol acylhydrazone Schiff base ligand in a beaker, add 2mL methanol, stirring at room temperature 25℃ for 10min, add 26μL triethylamine deprotonation, add 0.1mmol of dysprosium chloride hexahydrate continue to stir for 15min, get clear orange solution, volatilize at room temperature for 5 days, yellow crystals appear, which is trinuclear dysprosium single molecule magnets recorded as Dy3L2, crystal size is about 0.17mm×0.13mm×0.12mm.

[0063] Example 2

[0064] In the solution of 0.05mol methyl salicylate in ethanol solution, add 0.05mol of hydrazine hydrate, heated to reflux at 80℃ stirring 7h after get white turbid solution, suction filtration to get salicylic hydrazide.

[0065] In the solution of 0.046mol salicylic hydrazide in ethanol solution, add 0.046mol of 3-amino-2-hydroxyacetophenone, heated to reflux at 55℃ stirring 12h after get yellow green turbid solution, suction filtration to get yellow green powder intermediate W.

[0066] In the solution of 0.02mol intermediate W in ethanol solution, add 0.021mol of salicylaldehyde, heated to reflux at 75℃ stirring 12h get yellow turbid solution. Suction filtration to get yellow powder acylhydrazone Schiff base ligand recorded as L.

[0067] Take 0.05mmol acylhydrazone Schiff base ligand in a beaker, add 2mL methanol, stirring at room temperature 25℃ for 10min, add 26μL triethylamine deprotonation, add 0.1mmol of dysprosium chloride hexahydrate continue to stir for 15min, get clear orange solution, volatilize at room temperature for 5 days, yellow crystals appear, which is trinuclear dysprosium single molecule magnets recorded as Dy3L2.

[0068] Example 3

[0069] In the solution of 0.05mol methyl salicylate in ethanol solution, add 0.06mol of hydrazine hydrate, heated to reflux at 55℃ stirring 12h after get white turbid solution, suction filtration to get salicylic hydrazide.

[0070] In the solution of 0.046mol salicylic hydrazide in ethanol solution, add 0.0437mol of 3-amino-2-hydroxyacetophenone, heated to reflux at 60℃ stirring 12h after get yellow green turbid solution, suction filtration to get yellow green powder intermediate W.

[0071] In the solution of 0.02mol intermediate W in ethanol solution, add 0.019mol of salicylaldehyde, heated to reflux at 75℃ stirring 10h get yellow turbid solution. Suction filtration to get yellow powder acylhydrazone Schiff base ligand recorded as L.

[0072] Take 0.05 mmol of acylhydrazone Schiff base ligand in a beaker, add 2 mL of methanol, stir at room temperature 25 ℃ for 10 min, add 26 μL of triethylamine to deprotonate, add 0.1 mmol of dysprosium chloride hexahydrate to continue stirring for 15 min, get a clear orange solution, volatilize at room temperature for 5 days, yellow crystals appear, which is a trinuclear dysprosium single-molecule magnet recorded as Dy3L2.

[0073] Example 4

[0074] In the ethanol solution dissolved with 0.05 mol of methyl salicylate, 0.055 mol of hydrazine hydrate was added, and after stirring at 60 ℃ under reflux for 10 h, a white turbid solution was obtained. Filtration under suction gave salicylic hydrazide.

[0075] In the ethanol solution dissolved with 0.046 mol of salicylic hydrazide, 0.0483 mol of 3-amino-2-hydroxyacetophenone was added, and after stirring at 65 ℃ under reflux for 11 h, a yellow-green turbid solution was obtained. Filtration under suction gave yellow-green powder intermediate W.

[0076] In the ethanol solution dissolved with 0.02 mol of intermediate W, 0.02 mol of salicylaldehyde was added, and after stirring at 55 ℃ under reflux for 12 h, a yellow turbid solution was obtained. Filtration under suction gave yellow powder acylhydrazone Schiff base ligand recorded as L.

[0077] Take 0.05 mmol of acylhydrazone Schiff base ligand in a beaker, add 2 mL of methanol, stir at room temperature 25 ℃ for 10 min, add 26 μL of triethylamine to deprotonate, add 0.1 mmol of dysprosium chloride hexahydrate to continue stirring for 15 min, get a clear orange solution, volatilize at room temperature for 5 days, yellow crystals appear, which is a trinuclear dysprosium single-molecule magnet recorded as Dy3L2.

[0078] Example 5

[0079] In the ethanol solution dissolved with 0.05 mol of methyl salicylate, 0.05 mol of hydrazine hydrate was added, and after stirring at 70 ℃ under reflux for 8 h, a white turbid solution was obtained. Filtration under suction gave salicylic hydrazide.

[0080] In the ethanol solution dissolved with 0.046 mol of salicylic hydrazide, 0.046 mol of 3-amino-2-hydroxyacetophenone was added, and after stirring at 80 ℃ under reflux for 6 h, a yellow-green turbid solution was obtained. Filtration under suction gave yellow-green powder intermediate W.

[0081] In the ethanol solution dissolved with 0.02 mol of intermediate W, 0.02 mol of salicylaldehyde was added, and after stirring at 65 ℃ under reflux for 12 h, a yellow turbid solution was obtained. Filtration under suction gave yellow powder acylhydrazone Schiff base ligand recorded as L.

[0082] Take 0.05 mmol acylhydrazone Schiff base ligand in a beaker, add 2 mL of methanol, stirring at room temperature 25 ℃ for 10 min, add 26 μL of triethylamine deprotonation, add 0.1 mmol of dysprosium chloride hexahydrate to continue stirring for 15 min, to obtain a clear orange solution, volatilize at room temperature for 5 days, yellow crystals appear, which is a trinuclear dysprosium single molecule magnet recorded as Dy3L2.

[0083] Referring to Figure 3 , the spectral performance of the acylhydrazone Schiff base-based trinuclear dysprosium single molecule magnet Dy3L2 prepared in Example 1 is determined, and the infrared spectrum of the above acylhydrazone Schiff base ligand L is determined. The results show that: in the ligand infrared spectrum, ν C═O There is a characteristic peak at 1633 cm -1 (-C=O stretching vibration produces an absorption peak in the range of 1600-1690 cm -1 ). ν C═H There is a characteristic peak at 3003 cm -1 (-C-H stretching vibration produces an absorption peak in the range of 2943-3087 cm -1 ). ν C＝C There is a characteristic peak at (1473 cm -1 There is a characteristic peak at 1570-1492 cm -1 , which is the C=C stretching vibration peak on the aromatic ring). Referring to Figure 4 , the infrared spectrum of the trinuclear dysprosium single molecule magnet Dy3L2 prepared in Example 1 is determined and compared with the infrared spectrum of the ligand L. The results show that: the C=O vibration absorption peak on the ligand shifts from 1633 cm -1 to 1604 cm -1 , which has a significant shift, indicating that the carbonyl group participates in coordination, which is consistent with the crystal structure analysis.

[0084] The static magnetic behavior of the acylhydrazone Schiff base-based trinuclear dysprosium single molecule magnet Dy3L2 prepared in Example 1 is tested, referring to Figure 5 , the temperature-dependent direct current magnetization data of the acylhydrazone Schiff base-based trinuclear dysprosium single molecule magnet Dy3L2 in the temperature range of 2-300 K is tested under an external magnetic field of 1000 Oe. The χ M T value (41.68 cm 3 K mol -1 ) of the trinuclear dysprosium single molecule magnet Dy3L2 at room temperature 300 K is slightly lower than the theoretical value (42.51 cm III K mol 3 , S=5 / 2, -1 H 6 , g=4 / 3) of three uncoupled Dy 15 / 2 ions. As the temperature gradually decreases, χM The value of T decreases slowly with temperature, and χ M The value of T decreases rapidly with temperature, and χ M The value of T decreases to the minimum value of 42.51 cm 3 K mol -1 This is mainly due to the effect of the Stark sub-levels and the Dy III There is weak intramolecular / intermolecular antiferromagnetic interaction between the ions. In addition, χ M -1 The plot of χ M -1 The plot of χ M = C / (T - θ)) is linear with temperature T, and the Curie-Weiss fitting gives C = 42.44 cm 3 K mol -1 , θ = -7.13 K, indicating that there is weak antiferromagnetic interaction between the paramagnetic center ions in the complex. Referring to Figure 6 , the magnetization M of the magnet Dy3L2 was tested at temperatures of 2.0 K, 3.0 K, 4.0 K, and 5.0 K in a magnetic field of 0-70 kOe. At low fields, M increased rapidly with H, and the magnetic induction increased very rapidly. When the magnetic field reached 70 kOe, the magnetization M was lower than the theoretical saturation magnetization of three Dy III ions, indicating that there is magnetic anisotropy and / or low-energy excited states in the system of the magnet Dy3L2.

[0085] The dynamic magnetic behavior of the acylhydrazone-based Schiff base trinuclear dysprosium single-molecule magnet Dy3L2 prepared in Example 1 was tested, referring to Figure 7 The ac magnetic susceptibility of the trinuclear dysprosium single-molecule magnet Dy3L2 was measured under a 500 Oe direct current field with an oscillation field of 3 Oe. The results show that the real part χ' and the imaginary part χ" of the ac magnetic susceptibility signals can be observed in the measured frequency and temperature ranges, indicating that the trinuclear dysprosium single-molecule magnet Dy3L2 has single-molecule magnet properties. Referring to Figure 8 The ac magnetic susceptibility of the trinuclear dysprosium single-molecule magnet Dy3L2 was measured under a 500 Oe direct current field with an oscillation field of 3 Oe. The results show that the real part χ' and the imaginary part χ" of the ac magnetic susceptibility signals can be observed in the measured frequency and temperature ranges, indicating that the trinuclear dysprosium single-molecule magnet Dy3L2 has single-molecule magnet properties. Referring to

[0086] The acylhydrazone-based trinuclear dysprosium single-molecule magnet prepared by the method has a tetragonal crystal system and a P-421c space group; the cell parameters are: α = 90°, β = 90°, γ = 90°, Dc = 1.233 g / cm 3 , Z = 8, F(000) = 5680.0, μ(MoKa) = 2.874 mm -1 , GooF = 1.070, crystal size: 0.17 mm x 0.13 mm x 0.12 mm, R1 = 0.0495, wR2 = 0.1254 [I > = 2σ(I)]. The specific crystallographic data are shown in the following table:

[0087]

[0088]

[0089] [a] R1 = ∑||Fc|-|Fo|| / ∑|Fo|; [b] wR2 = {∑[w(Fo 2 -Fc 2 ) 2 ] /

[0090] ∑[w(Fo 2 ) 2 ]} 1 / 2

[0091] The molecular structure of the magnet Dy3L2 is shown in Figure 1 , and the figure shows that the acylhydrazone-based trinuclear dysprosium single-molecule magnet Dy3L2 has a chemical composition comprising 3 Dy Ⅲ ions, 2 partially deprotonated L ligands, 4 end-coordinated methanol molecules and 4 water molecules, and 1 free chloride ion; one Dy Ⅲ ion in the magnet is coordinated with 2 N atoms and 6 O atoms to form an 8-coordinated configuration, which is derived from 4 O atoms and 2 N atoms after deprotonation of 2 ligands L, and 2 O atoms of 2 methanol molecules; the other two Dy Ⅲ ions are coordinated with 1 N atom and 7 O atoms to form an 8-coordinated configuration, which is derived from 2 O atoms and 1 N atom after deprotonation of 1 ligand L, and 3 O atoms of 3 methanol molecules and 2 O atoms of 2 water molecules. The Dy-O and Dy-N bond lengths are shown in the following table, and it can be seen that the Dy-O and Dy-N bond lengths are within the normal range.

[0092] Partial bond lengths of the complex Dy3L2

[0093]

[0094]

[0095] In summary, the application provides a kind of trinuclear dysprosium single-molecule magnet based on acylhydrazone schiff base and preparation method, by using three-step hydrothermal reaction acylhydrazone schiff base ligand is synthesized, and after acylhydrazone schiff base ligand is deprotonated, dysprosium salt is added to react, and trinuclear dysprosium single-molecule magnet is obtained.The acylhydrazone schiff base ligand has suitable coordination ability and space configuration, can form stable coordination bond with rare earth ion, and the Dy 3+ Ion has the characteristics of large magnetic anisotropy, large magnetic moment, weak crystal field splitting, strong spin-orbit coupling, etc., and is easy to synthesize high-efficiency single-molecule magnet. It has good application prospect in the field of magnetic materials.

[0096] The above only describes the preferred embodiments of the application, and does not limit the technical solutions of the application in any way. Those skilled in the art should understand that the technical solutions can be modified and replaced in several simple ways without departing from the spirit and principles of the application, and these modifications and replacements also belong to the protection scope covered by the claims.

Claims

1. A trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base, characterized in that, Its chemical formula is: {[Dy3L2(CH3OH)4(H2O)4]·Cl}; Its molecular structural formula is: Wherein, L is an acylhydrazone Schiff base ligand.

2. The trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to claim 1, characterized in that, The molecular structure of the acylhydrazone Schiff base ligand is as follows:

3. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base as described in claim 1 or 2, characterized in that, include: Methyl salicylate was subjected to a first heating reaction with an alcoholic solution of hydrated hydrazine to obtain salicylhydrazine; Salicylic acid hydrazide and 3-amino-2-hydroxyacetophenone were dissolved in an alcohol solution and subjected to a second heating reaction to obtain intermediate W; The intermediate W and an alcoholic solution of salicylaldehyde were subjected to a third heating reaction to obtain the acylhydrazone Schiff base ligand. After deprotonation of the acylhydrazone Schiff base ligand, a dysprosium salt was added to react and a trinuclear dysprosium monomolecular magnet was obtained.

4. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to claim 3, characterized in that, The molar ratio of methyl salicylate to hydrated hydrazine is (1:1) to (1:1.2).

5. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to claim 3, characterized in that, The molar ratio of salicylhydrazine to 3-amino-2-hydroxyacetophenone is (1:0.95) to (1:1.05).

6. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to claim 3, characterized in that, The molar ratio of intermediate W to salicylaldehyde is (1:0.95) to (1:1.05).

7. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to claim 3, characterized in that, The molar ratio of acylhydrazone Schiff base ligand to dysprosium salt is (1:1) to (1:2).

8. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to claim 3, characterized in that, The temperature of the first heating reaction, the second heating reaction, and the third heating reaction is 55℃~80℃, and the reaction time is 6~12h.

9. The method for preparing a trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base according to any one of claims 3-8, characterized in that, The dysprosium salt is DyCl3·6H2O, and the reaction temperature is 15℃~35℃.

10. A trinuclear dysprosium single-molecule magnet based on an acylhydrazone Schiff base, prepared by the method according to any one of claims 3-9, characterized in that, This single-molecule magnet belongs to the tetragonal crystal system with space group P-421c; its unit cell parameters are: α=90°, β=90°, γ=90°, Dc = 1.233 g / cm³ 3 , Z=8, F(000)=5680.0, μ(MoKa)=2.874mm -1 GooF = 1.070, crystal size: 0.17mm × 0.13mm × 0.12mm, R1 = 0.0495, wR2 = 0.1254 [I>=2σ(I)].

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