Highly coordinated dysprosium single ion magnet and its preparation method and application

Abstract

The present invention discloses a high-coordinated dysprosium single-ion magnet and a preparation method and application thereof. The structural formula of the single-ion magnet is: [Dy(H3L)(C9H6NO)](BPh4)2. Compared with the prior art, the present invention has the following advantages: (1) The dysprosium single-ion magnet of the present invention has high purity and yield, can exhibit typical slow relaxation behavior under zero field and external magnetic field, has the characteristics of a single-ion magnet, and can be used as a molecular-based magnetic material in new high-density information storage devices (such as optical disks, hard disks, etc.); (2) The dysprosium single-ion magnet does not weather in the air and has good stability; (3) The method is safe and simple in process, highly controllable, and has good reproducibility.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic materials and relates to a single-ion magnet material, in particular to a high-coordinated dysprosium single-ion magnet and a preparation method and application thereof. Background Art

[0002] With the development of information technology, the number of electronic devices required to be integrated has increased exponentially while the size of devices has continued to decrease. The continuous development of this integration and miniaturization will be limited by processing technology and cost, resulting in insurmountable obstacles in modern electronic device integration technology. Therefore, the research and development of molecular-based magnetic materials has become a hot topic for scientists. Single-ion magnets (SIMs) are an important field of research on molecular-based magnetic materials. They also have great application potential in the fields of high-density information storage, quantum computers and molecular spinology.

[0003] Rare earth ions have a large number of single electrons and stronger spin-orbit coupling, making them ideal for designing single-ion magnets. Since Dy(III) has a Kramer electron layer structure (the f layer has an odd number of electrons), the ground state of the dysprosium-based single-ion magnet is bistable and is less affected by the coordination field. Therefore, dysprosium-based single-ion magnets have attracted the attention of many researchers and have become the best-performing single-ion magnet system, with an effective energy barrier and blocking temperature as high as 1540cm -1 and 80K. However, these single-ion magnets are often low-coordinated and therefore unstable at room temperature and in the air, and are easily decomposed or weathered. High-coordinated complexes, on the other hand, have good air stability. Summary of the invention

[0004] Technical problem to be solved: In order to overcome the shortcomings of the prior art, obtain a stable dysprosium complex with excellent single-molecule magnetic properties, and provide a synthesis method with mild and controllable synthesis conditions and good repeatability, the present invention provides a high-coordinated dysprosium single-ion magnet and its preparation method and application.

[0005] Technical solution: High-coordinated dysprosium single-ion magnet, the structural formula of the single-ion magnet is: [Dy(H3L)(C9H6NO)](BPh4)2, wherein the chemical structural formula of H3L is:

[0006]

[0007] The structural formula of C9H6NO is:

[0008]

[0009] Preferably, the chemical structural formula of the single ion magnet is:

[0010]

[0011] Preferably, the structural unit of the single ion magnet is: the crystal belongs to the monoclinic system, the C2 / c space group, and the unit cell parameters are α=90°, β=95.751(7)°, γ=90°.

[0012] Preferably, the Dy(III) is coordinated with seven nitrogen atoms of an H3L ligand and one nitrogen atom and one oxygen atom of an 8-hydroxyquinoline anion to form a nine-coordinated distorted single-crown tetragonal anti-prism configuration.

[0013] Preferably, the dysprosium single-ion magnet is a yellow block crystal, which can show typical slow relaxation behavior under the action of zero field and external magnetic field, respectively, and has the characteristics of a single-molecule magnet.

[0014] The method for preparing any of the above-mentioned highly coordinated dysprosium single-ion magnets comprises the following steps:

[0015] Dissolve tri(2-aminoethyl)amine and 4-imidazole carboxaldehyde in ultra-dry methanol, heat and reflux for 1 hour to obtain a light yellow clear solution; add the methanol solution containing dysprosium chloride to the yellow solution, stir for 6 hours, the color of the solution deepens, add the methanol solution containing 8-hydroxyquinoline to it, continue stirring for 1 hour, and then add the methanol solution containing sodium tetraphenylborate, immediately produce a large amount of precipitation, filter, dissolve the precipitation with acetonitrile, let it evaporate, and grow yellow block crystals, which is the dysprosium single ion magnet. The molar ratio of dysprosium chloride to tri(2-aminoethyl)amine and 4-imidazole carboxaldehyde is 1:3-3.5:1-1.5, and each 1mmol of dysprosium chloride corresponds to 25-35mL methanol, each 1mmol of dysprosium chloride corresponds to 1-2mmol of 8-hydroxyquinoline, each 1mmol of dysprosium chloride corresponds to 2-4mmol of sodium tetraphenylborate, and each 1mmol of dysprosium chloride corresponds to 10-15mL acetonitrile.

[0016] Preferably, the heating reflux temperature is 70°C.

[0017] Preferably, the volatilization time is 3 to 4 days.

[0018] Application of any of the above-mentioned high-coordinated dysprosium single-ion magnets in the preparation of molecule-based magnetic materials.

[0019] Beneficial effects: (1) The dysprosium single-ion magnet of the present invention can exhibit typical slow relaxation behavior under zero field, has the characteristics of a single-molecule magnet, and can be used as a molecular-based magnetic material in new high-density information storage devices (such as optical disks, hard disks, etc.); (2) The dysprosium single-ion magnet does not weather in the air and has good stability; (3) The method is safe and simple, has high controllability, and good reproducibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the crystal structure diagram of the highly coordinated dysprosium single ion magnet [Dy(H3L)(C9H6NO)](BPh4)2;

[0021] Figure 2 It is the powder X-ray diffraction pattern of the highly coordinated dysprosium single ion magnet [Dy(H3L)(C9H6NO)](BPh4)2;

[0022] Figure 3 This is the DC magnetic susceptibility test graph of the highly coordinated dysprosium single ion magnet [Dy(H3L)(C9H6NO)](BPh4)2;

[0023] Figure 4 It is a graph of the magnetization intensity of the highly coordinated dysprosium single ion magnet [Dy(H3L)(C9H6NO)](BPh4)2;

[0024] Figure 5 is the field-dependent imaginary AC susceptibility diagram of the highly coordinated dysprosium single-ion magnet [Dy(H3L)(C9H6NO)](BPh4)2;

[0025] Figure 6 This is the imaginary AC magnetic susceptibility diagram of the highly coordinated dysprosium single-ion magnet [Dy(H3L)(C9H6NO)](BPh4)2 at 800Oe. DETAILED DESCRIPTION

[0026] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, modifications and substitutions made to the method, steps or conditions of the present invention all belong to the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0027] Example 1

[0028] The invention discloses a preparation method of a high-coordinated dysprosium single-ion magnet, comprising: dissolving tri(2-aminoethyl)amine (3mmol) and 4-imidazolecarboxaldehyde (1mmol) in methanol (10mL), heating and refluxing at 70°C for 1h to obtain a light yellow clear solution; adding a methanol solution (5mL) containing dysprosium chloride (1mmol) to the yellow solution, stirring for 6h, the color of the solution deepens, adding a methanol solution (5mL) containing 8-hydroxyquinoline (1mmol) thereto, continuing to stir for 1h, and then adding a methanol solution (5mL) containing sodium tetraphenylborate (1mmol), immediately generating a large amount of precipitation, filtering, dissolving the precipitation with acetonitrile (10mL), leaving it to volatilize, and growing yellow block crystals, which are the dysprosium single-ion magnets.

[0029] The yield of the dysprosium single-molecule magnet prepared in this example is 67.1%.

[0030] Example 2

[0031] The invention discloses a preparation method of a high-coordinated dysprosium single-ion magnet, comprising: dissolving tri(2-aminoethyl)amine (3.5mmol) and 4-imidazolecarboxaldehyde (1mmol) in methanol (10mL), heating and refluxing at 70°C for 1h to obtain a light yellow clear solution; adding a methanol solution (5mL) containing dysprosium chloride (1mmol) to the yellow solution, stirring for 6h, the color of the solution deepens, adding a methanol solution (7mL) containing 8-hydroxyquinoline (1.5mmol) thereto, continuing to stir for 1h, and then adding a methanol solution (8mL) containing sodium tetraphenylborate (1.5mmol), immediately generating a large amount of precipitates, filtering, dissolving the precipitates with acetonitrile (10mL), leaving them to volatilize, and growing yellow block crystals, which are the dysprosium single-ion magnets.

[0032] The yield of the dysprosium single-molecule magnet prepared in this example is 69.5%.

[0033] The characterization of the dysprosium single ion magnet prepared in this example is as follows:

[0034] (1) Crystal structure determination

[0035] Select a single crystal of appropriate size under a microscope and use a graphite monochromatized molybdenum target Mo Kα on a Bruker SMARTApex IICCD single crystal instrument at room temperature. Test structure. The APEXII program was used to collect data and determine the unit cell. The structural data were normalized and absorption corrected using the SAINT and SADABS programs. The SHELXTL-2016 program was used for structural analysis. All non-hydrogen atomic coordinates were obtained by difference Fourier synthesis. The full matrix least squares method was used to correct the atomic coordinates and anisotropic temperature factors. All hydrogen atoms were hydrogenated using theory. The coordination structure diagram is shown in Figure 1 , the crystallographic data are shown in Table 1, and the coordination bond lengths are shown in Table 2.

[0036] Table 1 Crystallographic data of the complexes

[0037]

[0038] Table 2 Coordination bond length data of complexes

[0039]

[0040] Figure 1The structural diagram shows that Dy(III) is coordinated with seven nitrogen atoms of an H3L ligand and one nitrogen atom and one oxygen atom of an 8-hydroxyquinoline anion to form a nine-coordinated distorted single-crown tetragonal anti-prism configuration.

[0041] (2) Powder X-ray diffraction determination of phase purity

[0042] The phase purity of the bulk crystal product obtained in this example was characterized using a Bruker D8 Advance powder X-ray diffractometer. Figure 2 As shown, the simulation curve is obtained by simulating the single crystal structure data using Mercury software. The results show that the dysprosium single ion magnet material has reliable phase purity, which provides a guarantee for its application in molecular-based magnetic materials.

[0043] (3) Magnetic properties characterization

[0044] The magnetic measurement uses the superconducting quantum interference device QuantumDesignMPMS SQUID VSM magnetic measurement system. The test temperature of DC magnetic susceptibility is 2.0~300K, and the magnetic field is 0.1T. The test temperature of magnetization intensity is 2~5K, and the magnetic field is 0~7T. The frequency range of imaginary AC magnetic susceptibility and real AC magnetic susceptibility is 1~999Hz, and the temperature range is 2.5~20K.

[0045] like Figure 3 As shown in Figure 2, when the temperature is 300K, the product of the DC magnetic susceptibility (χ) and the temperature (T) is 13.76 cm 3 mol - 1 K, and spin-only Dy(III) (S = 5 / 2, L = 5, 6 H 15 / 2 ,g=4 / 3)The theoretical value is 14.17cm 3 kmol -1 The magnetization intensity curve ( Figure 4 ) shows that at a temperature of 2K, when the magnetic field reaches 7T, the magnetization intensity of the complex is 5.27Nβ, which does not reach the theoretical saturation value of 10Nβ, confirming that the complex has strong magnetic anisotropy. Under different external magnetic fields, the imaginary AC magnetic susceptibility of the complex χ M " show obvious frequency dependence ( Figure 5 ), resulting in slow magnetic relaxation behavior. Under the condition of an external DC field of 800Oe, the imaginary AC magnetic susceptibility χ" of the complex shows a strong temperature-dependent and frequency-dependent relaxation peak ( Figure 6 ), further confirming that the substance is a typical single-ion magnet.

[0046] Based on the above phenomena, the dysprosium single-ion magnet prepared by the present invention exhibits typical slow relaxation behavior under zero field and applied field, has the characteristics of a single-ion magnet, and can be used as a molecular-based magnetic material in new high-density information storage devices (such as optical disks, hard disks, etc.).

Claims

1. A highly coordinated dysprosium single ion magnet, characterized in that: The structural formula of the single ion magnet is: [Dy(H3L)(C9H6NO)](BPh4)2, wherein the chemical structural formula of H3L is: ; The structural formula of C9H6NO is: ; The chemical structural formula of the single ion magnet is: ； The structural unit of the single ion magnet is: the crystal belongs to the monoclinic system, C 2 / c space group, unit cell parameters are a = 23.180(8) Å, b = 13.989(5) Å, c = 44.601(16) Å, = 90°, = 95.751(7)°, =90°; The Dy(III) is coordinated with seven nitrogen atoms of an H3L ligand and one nitrogen atom and one oxygen atom of an 8-hydroxyquinoline anion to form a nine-coordinated distorted single-crown tetragonal anti-prism configuration; The dysprosium single-ion magnet is a yellow block crystal, which can show typical slow relaxation behavior under the action of zero field and external magnetic field, and has the characteristics of a single-molecule magnet.

2. The method for synthesizing a highly coordinated dysprosium single ion magnet according to claim 1, characterized in that: Dissolve tri(2-aminoethyl)amine and 4-imidazolecarboxaldehyde in ultra-dry methanol, heat under reflux for 1 h to obtain a light yellow clear solution; add the methanol solution containing dysprosium chloride to the yellow solution, stir for 6 h, the color of the solution deepens, add the methanol solution containing 8-hydroxyquinoline, continue stirring for 1 h, then add the methanol solution containing sodium tetraphenylborate, a large amount of precipitation is immediately generated, filter, dissolve the precipitate with acetonitrile, let it evaporate, and grow yellow block crystals, which are dysprosium single ion magnets; wherein the molar ratio of dysprosium chloride to tri(2-aminoethyl)amine and 4-imidazolecarboxaldehyde is 1:3~3.5:1~1.5, each 1 mmol of dysprosium chloride corresponds to 25~35 mL of methanol, each 1 mmol of dysprosium chloride corresponds to 1~2 mmol of 8-hydroxyquinoline, each 1 mmol of dysprosium chloride corresponds to 2~4 mmol of sodium tetraphenylborate, and each 1 mmol of dysprosium chloride corresponds to 10~15 mL of acetonitrile.

3. The method for synthesizing a highly coordinated dysprosium single ion magnet according to claim 2, characterized in that: The heating reflux temperature was 70°C.

4. The method for synthesizing a highly coordinated dysprosium single ion magnet according to claim 3, characterized in that: The volatilization time is 3 to 4 days.

5. Use of the highly coordinated dysprosium single ion magnet according to claim 1 in the preparation of molecule-based magnetic materials.

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