Preparation method of high-symmetry dysprosium-based monomolecular magnet

Abstract

The invention relates to the technical field of preparation of monomolecular magnets, and particularly discloses a preparation method of a high-symmetry dysprosium-based monomolecular magnet, which comprises the following steps: pretreating dysprosium nitrate hexahydrate, 1, 3, 5-benzene tricarboxylic acid, 4, 4 '-dipyridyl, N, N-dimethylformamide and methanol for later use, respectively adding the 1, 3, 5-benzene tricarboxylic acid and the 4, 4'-dipyridyl into the N, N-dimethylformamide, and reacting for 2-4 hours to obtain a dysprosium-based monomolecular magnet with high symmetry. Dissolving in N, N-dimethylformamide, and mixing to prepare a mixed ligand solution; and dissolving the dysprosium nitrate hexahydrate in methanol, dropwise adding the solution into the mixed ligand solution, and carrying out hydrothermal reaction to obtain the high-symmetry dysprosium-based single-molecular magnet. 1, 3, 5-benzene tricarboxylic acid with a symmetrical benzene ring structure and rare earth metal dysprosium ions form a symmetrical coordination structure, meanwhile, a symmetrical coordination environment can be further constructed around the metal ions through a linear symmetrical structure of 4, 4 '-dipyridyl, the symmetry of the complex is greatly improved, the magnetic anisotropy of the complex is higher due to the high symmetry, and the rare earth metal dysprosium complex can be used for preparing a rare earth metal dysprosium complex. And the quantum tunneling effect is weaker.

Description

Technical Field

[0001] The present invention relates to the technical field of single-molecule magnet preparation, and in particular to a method for preparing a high-symmetry dysprosium-based single-molecule magnet. Background Art

[0002] The research on single-molecule magnets began in the late 1980s, when scientists discovered that some transition metal complexes and rare earth metal complexes with specific structures exhibited hysteresis phenomena similar to macroscopic magnets at low temperatures, thus opening up the research field of single-molecule magnets.

[0003] The magnetism of single-molecule magnets stems primarily from the unpaired electrons of the central metal ion and the interaction between the ligands and the metal ion. At low temperatures, the spins of these unpaired electrons can maintain their orientation to a certain extent, giving the individual molecules a magnetic moment and exhibiting magnetism.

[0004] With the cross-disciplinary development of synthetic chemistry, materials science, physical chemistry and other disciplines, more and more single-molecule magnets with different structures and properties have been synthesized and studied, their magnetic properties have been continuously improved, and their application fields have been continuously expanded.

[0005] In terms of quantum information storage, single-molecule magnets are expected to become ideal materials for high-density information storage due to their nanoscale size and unique magnetic properties; in the field of quantum computing, the spin states of single-molecule magnets can be used as candidates for quantum bits to realize the processing and transmission of quantum information; in spin electronics, single-molecule magnets can be used to develop new spin electronic devices, such as spin valves, magnetic sensors, etc.

[0006] However, the magnetic anisotropy of existing single-molecule magnets is not strong enough, which makes them easily disturbed by external magnetic fields in practical applications. The magnetic state is not stable enough, affecting the accuracy of information storage and the reliability of quantum computing. At the same time, their short magnetic relaxation time makes it difficult to meet the long-term stability requirements for information storage and processing in practical applications. Moreover, the existing synthesis methods have harsh conditions and high preparation costs.

[0007] Therefore, it is necessary to design a preparation method for highly symmetric dysprosium-based single-molecule magnets to solve the problems of weak magnetic anisotropy, short magnetic relaxation time and harsh synthesis conditions of existing single-molecule magnets. Summary of the Invention

[0008] In view of this, the present invention proposes a method for preparing a highly symmetric dysprosium-based single-molecule magnet, aiming to solve the problems of weak magnetic anisotropy, short magnetic relaxation time and harsh synthesis conditions of existing single-molecule magnets.

[0009] The present invention provides a method for preparing a high-symmetry dysprosium-based single-molecule magnet, comprising the following steps:

[0010] Dysprosium nitrate hexahydrate, 1,3,5-benzenetricarboxylic acid, 4,4'-bipyridine, N,N-dimethylformamide and methanol are pretreated and then used;

[0011] 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine are respectively added to N,N-dimethylformamide and stirred until completely dissolved to obtain a first ligand solution and a second ligand solution; dysprosium nitrate hexahydrate is added to methanol and stirred until completely dissolved to obtain a metal salt solution;

[0012] The first ligand solution and the second ligand solution are first mixed to obtain a mixed ligand solution, and then the metal salt solution is dropwise added to the mixed ligand solution for second mixing to obtain a first mixed solution, and an alkaline regulator is added to the first mixed solution to adjust the pH value to between 6 and 8;

[0013] The first mixed solution is subjected to a hydrothermal reaction, and after the reaction is completed, the product is post-treated to obtain the high-symmetry dysprosium-based single-molecule magnet.

[0014] Furthermore, the preprocessing is specifically as follows:

[0015] The dysprosium nitrate hexahydrate was vacuum dried at 60° C. for 12 hours; the 1,3,5-benzenetricarboxylic acid was added to anhydrous ethanol and recrystallized twice; the 4,4'-bipyridine was added to toluene and refluxed for purification, and then distilled under reduced pressure; the N,N-dimethylformamide and methanol were dried for 24 hours.

[0016] Furthermore, the concentrations of the first ligand solution and the second ligand solution are 0.1-0.5 mol / L; and the concentration of the metal salt solution is 0.2-0.6 mol / L.

[0017] Furthermore, the first mixing is specifically: stirring and mixing the first ligand solution and the second ligand solution at a speed of 200-300 rpm for 1-2 hours.

[0018] Furthermore, the second mixing step specifically comprises: adding the metal salt solution dropwise to the mixed ligand solution at a rate of 0.5-1 drop / second under a stirring speed of 300-400 rpm.

[0019] Furthermore, the volume ratio of the metal salt solution to the mixed ligand solution is 1:1-1.5.

[0020] Furthermore, the hydrothermal reaction is specifically as follows: the temperature is raised to 135° C. at a heating rate of 2-3° C. / min, maintained for 80 hours, and then cooled to room temperature at a cooling rate of 1-2° C. / min.

[0021] Furthermore, the alkaline regulator is sodium hydroxide or triethylamine.

[0022] Furthermore, the post-treatment is specifically as follows: filtering out the solid product with a microporous filter membrane with a pore size of 0.22 μm, washing the solid product alternately with methanol and deionized water for 5 times, soaking for 30 minutes each time, and vacuum drying the washed solid product at 55° C. for 18 hours.

[0023] Furthermore, the stirring speed of the first stirring is 200-300 rpm.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention selects 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine as ligands. 1,3,5-benzenetricarboxylic acid has a symmetrical benzene ring structure and three carboxyl functional groups, and can form a symmetrical coordination structure with metal ions. 4,4'-bipyridine is used as a bridging ligand, and its linear symmetrical structure can further construct a symmetrical coordination environment around the metal ions, greatly improving the overall symmetry of the dysprosium-based single-molecule magnet. The highly symmetrical structure enhances the magnetic anisotropy and stability of the dysprosium-based single-molecule magnet of the present invention.

[0026] 2. The present invention adopts a hydrothermal method to prepare a high-symmetry dysprosium-based single-molecule magnet, which has milder reaction conditions and lower preparation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0028] Figure 1 Flow chart of the preparation method of the highly symmetric dysprosium-based single-molecule magnet provided in the embodiment of the present application. DETAILED DESCRIPTION

[0029] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0030] The present invention selects 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine as ligands. 1,3,5-benzenetricarboxylic acid has a symmetrical benzene ring structure and three carboxyl functional groups, which helps to form a symmetrical coordination structure with metal ions. 4,4'-bipyridine is used as a bridging ligand, and its linear symmetrical structure can further construct a symmetrical coordination environment around the metal ions, greatly improving the overall symmetry of the dysprosium-based single-molecule magnet. The highly symmetrical structure greatly enhances the magnetic anisotropy and stability of the dysprosium-based single-molecule magnet of the present invention.

[0031] In some embodiments of the present invention, a method for preparing a high-symmetry dysprosium-based single-molecule magnet comprises the following steps:

[0032] Dysprosium nitrate hexahydrate, 1,3,5-benzenetricarboxylic acid, 4,4'-bipyridine, N,N-dimethylformamide and methanol are pretreated and then used;

[0033] 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine are respectively added to N,N-dimethylformamide and stirred until completely dissolved to obtain a first ligand solution and a second ligand solution; dysprosium nitrate hexahydrate is added to methanol and stirred until completely dissolved to obtain a metal salt solution;

[0034] The first ligand solution and the second ligand solution are first mixed to obtain a mixed ligand solution, and then the metal salt solution is dropwise added to the mixed ligand solution for second mixing to obtain a first mixed solution, and an alkaline regulator is added to the first mixed solution to adjust the pH value to between 6 and 8;

[0035] The first mixed solution is subjected to a hydrothermal reaction, and after the reaction is completed, the product is post-treated to obtain the high-symmetry dysprosium-based single-molecule magnet.

[0036] Specifically, the purity of the dysprosium nitrate hexahydrate, 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine is ≥99.9%.

[0037] Specifically, when performing the hydrothermal reaction, the first mixed solution is first transferred to a stainless steel reactor with a polytetrafluoroethylene lining, the filling degree of which is precisely controlled at 70%, and then placed in an oven for the hydrothermal reaction.

[0038] It is understandable that precisely controlling the filling degree at 70% can provide the reaction system with appropriate expansion space during the heating process, thereby avoiding damage to the reactor due to excessive pressure.

[0039] In some embodiments of the present invention, the preprocessing is specifically:

[0040] The dysprosium nitrate hexahydrate was vacuum dried at 60° C. for 12 hours; the 1,3,5-benzenetricarboxylic acid was added to anhydrous ethanol and recrystallized twice; the 4,4'-bipyridine was added to toluene and refluxed for purification, and then distilled under reduced pressure; the N,N-dimethylformamide and methanol were dried for 24 hours.

[0041] Specifically, 4A molecular sieves are used to dry N,N-dimethylformamide and methanol; the reflux purification and reduced pressure distillation are both carried out using conventional technical means in the art.

[0042] It can be understood that vacuum drying dysprosium nitrate hexahydrate at 60°C for 12 hours can remove trace impurities that may be contained in the crystallization water and ensure the activity of metal ions; adding 1,3,5-benzenetricarboxylic acid to anhydrous ethanol for recrystallization, adding 4,4'-bipyridine to toluene for reflux purification, and then performing reduced pressure distillation can improve the purity of the ligand and reduce the interference of impurities on the coordination reaction.

[0043] In some embodiments of the present invention, the concentrations of the first ligand solution and the second ligand solution are 0.1-0.5 mol / L; and the concentration of the metal salt solution is 0.2-0.6 mol / L.

[0044] Specifically, the concentrations of the first ligand solution and the second ligand solution are preferably 0.3 mol / L, and the concentration of the metal salt solution is preferably 0.4 mol / L.

[0045] In some embodiments of the present invention, the first mixing is specifically: stirring the first ligand solution and the second ligand solution at a speed of 200-300 rpm for 1-2 hours; the stirring speed is preferably 250 rpm, and the stirring time is preferably 1.5 hours.

[0046] In some embodiments of the present invention, the second mixing is specifically: adding the metal salt solution to the mixed ligand solution at a rate of 0.5-1 drops / second at a stirring speed of 300-400 rpm; the stirring speed is preferably 350 rpm, and the dropping speed is preferably 0.8 drops / second.

[0047] It is understood that slowly adding the metal salt solution allows the metal ions to be evenly distributed in the mixed ligand solution, avoiding localized excessive metal ion concentrations. Furthermore, a stirring speed of 300-400 rpm continuously disperses the added metal salt solution, allowing for full contact between the metal ions and the ligands, providing a good foundation for subsequent coordination reactions and helping to form a uniform and structurally stable single-molecule magnet.

[0048] It is understandable that slow addition and appropriate stirring speed can precisely regulate the reaction rate between metal ions and ligands. Through such precise control, the coordination reaction can proceed according to the expected stoichiometric ratio, ensuring the consistency of the structure and performance of the generated product, and improving the purity and quality of the product.

[0049] It is understandable that a uniform mixing system helps the molecules to arrange in an orderly manner during crystal growth, forming a highly symmetric crystal structure, thereby improving the symmetry and related magnetic properties of the dysprosium-based single-molecule magnet.

[0050] In some embodiments of the present invention, the volume ratio of the metal salt solution to the mixed ligand solution is 1:1-1.5; the volume ratio of the metal salt solution to the mixed ligand solution is preferably 1:1.5.

[0051] In some embodiments of the present invention, the hydrothermal reaction is specifically as follows: the temperature is raised to 135°C at a heating rate of 2-3°C / min, maintained for 80 hours, and then cooled to room temperature at a cooling rate of 1-2°C / min; the heating rate is preferably 2.3°C / min, and the cooling rate is preferably 1.5°C / min.

[0052] Understandably, when the temperature is slowly increased, the reaction system is heated evenly, giving the molecules ample time to arrange themselves in an orderly manner. Metal ions and ligands can bind more stably and gradually grow according to a specific lattice structure, which is conducive to the formation of a regular, complete, and highly symmetrical crystal structure. In contrast, rapid temperature increase may lead to local overheating, causing disordered crystal growth and affecting the symmetry and magnetic properties of the single-molecule magnet.

[0053] It's understandable that during a slow heating process, the temperature changes uniformly across the reaction system, preventing the generation of internal stresses due to large temperature gradients. Similarly, slow cooling allows the crystal to shrink evenly during cooling, preventing stress concentration that could lead to crystal cracking or defects. Internal stresses and defects can reduce the stability and magnetic properties of single-molecule magnets, and slow heating and cooling effectively prevent these problems.

[0054] Understandably, the slow heating and cooling process provides a more stable reaction environment, favoring the formation of the target product and reducing the occurrence of side reactions. A stable reaction environment allows for more precise coordination reactions between metal ions and ligands, thereby improving product purity and reducing the impact of impurities on the performance of single-molecule magnets.

[0055] In some embodiments of the present invention, the alkaline regulator is sodium hydroxide or triethylamine.

[0056] It is understood that adjusting the pH of the reaction system to a neutral environment using an alkaline regulator allows the coordination reaction between the dysprosium ion in dysprosium nitrate and 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine to proceed more stably and efficiently. Excessively acidic conditions can protonate groups such as the carboxyl group of the ligand, affecting its coordination with the metal ion. Excessively alkaline conditions can cause the metal ion to form a hydroxide precipitate, which is also detrimental to the coordination reaction. A neutral pH allows the metal ion and ligand to coordinate in an appropriate stoichiometric ratio and spatial configuration, contributing to the formation of a highly symmetrical structure.

[0057] It is understandable that in the subsequent hydrothermal reaction, a neutral pH reaction system is conducive to the stable growth of crystals. It provides a suitable chemical environment for crystal growth, allowing the atoms or molecules to be arranged in an orderly manner during the crystal growth process, promoting the formation of a highly symmetric crystal structure, and thus improving the crystallinity and magnetic properties of the dysprosium-based single-molecule magnet.

[0058] It is understood that the use of sodium hydroxide or triethylamine as alkaline modifiers, during the pH adjustment process, does not introduce ions or groups that could negatively impact the product structure and properties. The sodium ions introduced by sodium hydroxide and the cations formed by protonation of triethylamine are easily removed during the subsequent washing and drying processes, and do not remain in the product to affect the symmetry of the crystal structure and magnetic properties of the single-molecule magnet, thereby ensuring product purity and quality.

[0059] In some embodiments of the present invention, the post-treatment is specifically: filtering out the solid product with a microporous filter membrane with a pore size of 0.22 μm, washing the solid product alternately with methanol and deionized water for 5 times, soaking for 30 minutes each time, and vacuum drying the washed solid product at 55°C for 18 hours.

[0060] It can be understood that methanol is an organic solvent that can dissolve and remove organic impurities attached to the surface of the product, such as unreacted ligands, organic solvent residues, etc., while deionized water can dissolve and wash away water-soluble impurities on the surface of the product, such as ionic impurities of metal salts. The alternating use of the two can fully cover impurities of different properties and ensure the purity of the product.

[0061] Understandably, the relatively mild drying temperature of 55°C prevents the structure of the single-molecule magnet from being damaged by heat, leading to a loss of symmetry or altered magnetic properties. Furthermore, the 18-hour drying time is long enough to allow the product to fully dry at a stable temperature, maintaining its crystal structure and molecular configuration, ensuring its high symmetry and excellent magnetic properties.

[0062] Example 1

[0063] S1. The dysprosium nitrate hexahydrate is vacuum dried at 60° C. for 12 hours before use; the 1,3,5-benzenetricarboxylic acid is added to anhydrous ethanol and recrystallized twice before use; the 4,4'-bipyridine is added to toluene and refluxed for purification, and then subjected to reduced pressure distillation before use; the N,N-dimethylformamide and methanol are dried using 4A molecular sieves for 24 hours before use.

[0064] S2. Add 1,3,5-benzenetricarboxylic acid to N,N-dimethylformamide, stir at 200 rpm until completely dissolved, and prepare a first ligand solution with a concentration of 0.1 mol / L; add 4,4'-bipyridine to N,N-dimethylformamide, stir at 200 rpm until completely dissolved, and prepare a second ligand solution with a concentration of 0.1 mol / L; add dysprosium nitrate hexahydrate to methanol, stir until completely dissolved, and prepare a metal salt solution with a concentration of 0.2 mol / L.

[0065] S3. The first ligand solution and the second ligand solution were stirred and mixed at a speed of 200 rpm for 1 hour, and the metal salt solution was added dropwise to the mixed ligand solution at a rate of 0.5 drops per second at a stirring speed of 300 rpm in a volume ratio of 1:1 to obtain a first mixed solution, and sodium hydroxide was added to the first mixed solution until the pH value of the first mixed solution was between 6 and 8.

[0066] S4. Transfer the first mixed solution to a stainless steel reactor with a polytetrafluoroethylene lining, and accurately control the filling degree at 70%. After sealing the reactor, place it in an oven, and heat it from room temperature to 135°C at a heating rate of 2°C / min. Carry out hydrothermal reaction at 135°C for 80 hours. After the reaction is completed, naturally cool it to room temperature at a cooling rate of 1°C / min, filter out the solid product with a microporous filter membrane with a pore size of 0.22μm, and wash the solid product alternately with methanol and deionized water for 5 times, soaking for 30 minutes each time, and vacuum dry the washed solid product at 55°C for 18 hours to obtain the highly symmetric dysprosium-based single-molecule magnet.

[0067] Example 2

[0068] S1. The dysprosium nitrate hexahydrate is vacuum dried at 60° C. for 12 hours before use; the 1,3,5-benzenetricarboxylic acid is added to anhydrous ethanol and recrystallized twice before use; the 4,4'-bipyridine is added to toluene and refluxed for purification, and then subjected to reduced pressure distillation before use; the N,N-dimethylformamide and methanol are dried using 4A molecular sieves for 24 hours before use.

[0069] S2. Add 1,3,5-benzenetricarboxylic acid to N,N-dimethylformamide, stir at 250 rpm until completely dissolved, and prepare a first ligand solution with a concentration of 0.3 mol / L; add 4,4'-bipyridine to N,N-dimethylformamide, stir at 250 rpm until completely dissolved, and prepare a second ligand solution with a concentration of 0.3 mol / L; add dysprosium nitrate hexahydrate to methanol, stir until completely dissolved, and prepare a metal salt solution with a concentration of 0.4 mol / L.

[0070] S3. The first ligand solution and the second ligand solution were stirred and mixed at a speed of 250 rpm for 1.5 hours, and the metal salt solution was added dropwise to the mixed ligand solution at a rate of 0.8 drops per second at a stirring speed of 350 rpm at a volume ratio of 1:1.5 to obtain a first mixed solution, and triethylamine was added to the first mixed solution until the pH value of the first mixed solution was between 6 and 8.

[0071] S4. Transfer the first mixed solution to a stainless steel reactor with a polytetrafluoroethylene lining, and accurately control the filling degree at 70%. After sealing the reactor, place it in an oven, and heat it from room temperature to 135°C at a heating rate of 2.5°C / min. Carry out hydrothermal reaction at 135°C for 80 hours. After the reaction is completed, naturally cool it to room temperature at a cooling rate of 1.5°C / min, filter out the solid product with a microporous filter membrane with a pore size of 0.22μm, and wash the solid product alternately with methanol and deionized water for 5 times, soaking for 30 minutes each time, and vacuum dry the washed solid product at 55°C for 18 hours to obtain the highly symmetric dysprosium-based single-molecule magnet.

[0072] Example 3

[0073] S1. The dysprosium nitrate hexahydrate is vacuum dried at 60° C. for 12 hours before use; the 1,3,5-benzenetricarboxylic acid is added to anhydrous ethanol and recrystallized twice before use; the 4,4'-bipyridine is added to toluene and refluxed for purification, and then subjected to reduced pressure distillation before use; the N,N-dimethylformamide and methanol are dried using 4A molecular sieves for 24 hours before use.

[0074] S2. Add 1,3,5-benzenetricarboxylic acid to N,N-dimethylformamide, stir at 300 rpm until completely dissolved, and prepare a first ligand solution with a concentration of 0.5 mol / L; add 4,4'-bipyridine to N,N-dimethylformamide, stir at 300 rpm until completely dissolved, and prepare a second ligand solution with a concentration of 0.5 mol / L; add dysprosium nitrate hexahydrate to methanol, stir until completely dissolved, and prepare a metal salt solution with a concentration of 0.6 mol / L.

[0075] S3. The first ligand solution and the second ligand solution were stirred and mixed at a speed of 300 rpm for 2 hours, and the metal salt solution was added dropwise to the mixed ligand solution at a volume ratio of 1:1.5 at a stirring speed of 400 rpm at a rate of 1 drop / second to obtain a first mixed solution, and triethylamine was added to the first mixed solution until the pH value of the first mixed solution was between 6 and 8.

[0076] S4. Transfer the first mixed solution to a stainless steel reactor with a polytetrafluoroethylene lining, and accurately control the filling degree at 70%. After sealing the reactor, place it in an oven, and heat it from room temperature to 135°C at a heating rate of 3°C / min. Carry out hydrothermal reaction at 135°C for 80 hours. After the reaction is completed, naturally cool it to room temperature at a cooling rate of 2°C / min, filter out the solid product with a microporous filter membrane with a pore size of 0.22μm, and wash the solid product alternately with methanol and deionized water for 5 times, soaking for 30 minutes each time, and vacuum dry the washed solid product at 55°C for 18 hours to obtain the highly symmetric dysprosium-based single-molecule magnet.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a highly symmetric dysprosium-based single-molecule magnet, characterized in that: The following steps are involved: Dysprosium nitrate hexahydrate, 1,3,5-benzenetricarboxylic acid, 4,4'-bipyridine, N,N-dimethylformamide and methanol are pretreated and then used; 1,3,5-benzenetricarboxylic acid and 4,4'-bipyridine are respectively added to N,N-dimethylformamide and stirred until completely dissolved to obtain a first ligand solution and a second ligand solution; dysprosium nitrate hexahydrate is added to methanol and stirred until completely dissolved to obtain a metal salt solution; The first ligand solution and the second ligand solution are first mixed to obtain a mixed ligand solution, and then the metal salt solution is dropwise added to the mixed ligand solution for second mixing to obtain a first mixed solution, and an alkaline regulator is added to the first mixed solution to adjust the pH value to between 6 and 8; The first mixed solution is subjected to a hydrothermal reaction, and after the reaction is completed, the product is post-treated to obtain the high-symmetry dysprosium-based single-molecule magnet.

2. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, characterized in that: The pre-processing is specifically as follows: The dysprosium nitrate hexahydrate was vacuum dried at 60° C. for 12 hours; the 1,3,5-benzenetricarboxylic acid was added to anhydrous ethanol and recrystallized twice; the 4,4'-bipyridine was added to toluene and refluxed for purification, and then distilled under reduced pressure; the N,N-dimethylformamide and methanol were dried for 24 hours.

3. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, wherein: The concentrations of the first ligand solution and the second ligand solution are 0.1-0.5 mol / L; the concentration of the metal salt solution is 0.2-0.6 mol / L.

4. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, wherein: The first mixing is specifically: stirring and mixing the first ligand solution and the second ligand solution at a speed of 200-300 rpm for 1-2 hours.

5. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, characterized in that: The second mixing step specifically includes: adding the metal salt solution dropwise to the mixed ligand solution at a rate of 0.5-1 drop / second under a stirring speed of 300-400 rpm.

6. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, characterized in that: The volume ratio of the metal salt solution to the mixed ligand solution is 1:1-1.

5.

7. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, characterized in that: The hydrothermal reaction is specifically as follows: the temperature is raised to 135° C. at a heating rate of 2-3° C. / min, maintained for 80 hours, and then cooled to room temperature at a cooling rate of 1-2° C. / min.

8. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, characterized in that: The alkaline regulator is sodium hydroxide or triethylamine.

9. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, wherein: The post-treatment is specifically as follows: filtering out the solid product with a microporous filter membrane with a pore size of 0.22 μm, washing the solid product with methanol and deionized water alternately for 5 times, soaking for 30 minutes each time, and vacuum drying the washed solid product at 55° C. for 18 hours.

10. The method for preparing a high-symmetry dysprosium-based single-molecule magnet according to claim 1, characterized in that: The stirring speed of the first stirring is 200-300 rpm.

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