Five-core cobalt molecule-based magnet, preparation method and application thereof

Abstract

The invention belongs to the technical field of transition complex preparation, and discloses a five-core cobalt molecule-based magnet as well as a preparation method and application thereof. The preparation method provided by the invention comprises the following steps: mixing and dissolving organic ligands H2L, Dy (CF3SO3) 3, CoI2 and NaN3 in a mixed solution of methanol and deionized water according to a certain proportion, then adding Et3N, reacting the mixed solution in a reaction kettle with a polytetrafluoroethylene liner for 10 hours at the reaction temperature of 80 DEG C, and obtaining purple crystals after the reaction is completed. The five-core cobalt complex is an ionic molecule-based magnet and can be applied to preparation of molecular magnetic materials and molecular memory materials.

Description

Technical Field

[0001] The invention belongs to the technical field of transition complex preparation, and relates to a pentanuclear cobalt molecule-based magnet, a preparation method and an application thereof. Background Art

[0002] Molecular magnets are paramagnetic molecules that can be magnetized below a specific temperature and have potential applications in high-density information storage, magnetic qubits, spintronic devices, etc. (Chinese Journal of Chemistry, 2020, 38(9): 1005-1018). Most 3d-SMMs with transition metals as paramagnetic centers require an external magnetic field to suppress the magnetization quantum tunneling effect (QTM). Therefore, it is very necessary to use external factors to weaken the quantum tunneling effect. For mononuclear transition metal molecular magnets, the number of coordination of the metal center is usually reduced to provide a relatively strong ligand field, thereby weakening the 3d orbital splitting energy. Dual-nuclear and above multi-nuclear transition metal molecular magnets mainly explore the influence of magnetic interactions and the coordination environment and geometric configuration of the metal center on magnetic relaxation behavior and quantum tunneling effect, and clarify the magnetic relaxation mechanism. Mononuclear transition molecular magnets have unique magnetic properties and research value, but there are still some challenges in synthesis, preparation and practical application. Pentanuclear transition molecular magnets refer to single molecules composed of five transition metal atoms, which have specific magnetic properties. This material usually exhibits quantum magnetic behavior based on the atomic scale, which is of great significance for understanding nanoscale magnetism and developing new magnetic materials. Due to their unique structure and magnetic properties, these molecular-based magnets have important potential value in studying nanoscale magnetism, developing new magnetic materials and in the field of information storage. Summary of the invention

[0003] The purpose of the present invention is to provide a pentanuclear cobalt molecule-based magnet, a preparation method and an application thereof. The pentanuclear cobalt molecule-based magnet is an ionic molecule-based magnet, which enriches the structural types of transition molecule-based magnets and provides a new idea for the synthesis and application of new transition molecule-based magnets.

[0004] The technical solution provided by the present invention is as follows: a pentanuclear cobalt molecule-based magnet, which is an ionic molecule-based magnet belonging to the orthorhombic crystal system, with a molecular formula of [Co4(HL)4(N3)2][Co(HL)2]I2 (complex 1, H2L = (1S, 2S)-1,2-di(1-methyl-1H-benzo[d]imidazol-2-yl)ethane-1,2-diol, HL = partially deprotonated (1S, 2S)-1,2-di(1-methyl-1H-benzo[d]imidazol-2-yl)ethane-1,2-diol), a space group of I222, and a unit cell parameter of: α=β=γ=90°,

[0005] A method for preparing the above-mentioned pentanuclear cobalt molecular-based magnet having an ionic molecular-based magnet specifically comprises the following steps:

[0006] S1. The organic ligands H2L, Dy(CF3SO3)3, CoI2, and NaN3 are mixed and dissolved in a mixed solvent of methanol and deionized water, and then Et3N is added to obtain a mixed solution;

[0007] S2. The mixed solution is heated in a reactor with a polytetrafluoroethylene liner for reaction, and the pentanuclear cobalt molecule-based magnet is obtained after the reaction is completed.

[0008] The synthesis route of the pentanuclear cobalt molecule-based magnet is shown below:

[0009]

[0010] In the above formula, complex 1 is [Co4(HL)4(N3)2][Co(HL)2]I2.

[0011] Furthermore, in the above-mentioned preparation method, the molar ratio of the organic ligands H2L, Dy(CF3SO3)3, CoI2, NaN3, and Et3N is 10:1:5:2:10.

[0012] Furthermore, the volume ratio of methanol to deionized water in the mixed solvent is 2:1 to 1:2.

[0013] Furthermore, the volume ratio of methanol to deionized water in the mixed solvent is 1:1.

[0014] Furthermore, the amount of the mixed solvent used per 0.1 mmol of the organic ligand H2L is 4-8 mL.

[0015] Furthermore, the amount of the mixed solvent used for every 0.1 mmol of the organic ligand H2L is 6 mL.

[0016] Furthermore, the temperature of the heating reaction is 70-90°C, and the reaction time is 8-12h.

[0017] Furthermore, the temperature of the heating reaction is 80° C. and the reaction time is 10 h.

[0018] The present invention also provides an application of the pentanuclear cobalt molecule-based magnet or the pentanuclear cobalt molecule-based magnet prepared by the preparation method in molecular magnetic materials.

[0019] Compared with the prior art, the present invention utilizes N-rich and O-rich chiral organic ligands H2L to successfully obtain an ionic pentanuclear cobalt molecule-based magnet through a solvothermal method. The preparation method is simple and the raw materials are readily available. The transition molecule-based magnet is formed by designing the organic ligand structure to react with the transition metal, which enriches the structural types of the transition molecule-based magnet and provides a new direction for the exploration of its structural field. The synthesized compound can be used in the preparation of molecular magnetic materials or molecular memory materials and has potential application value in the fields of high-density information storage, quantum computing, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of the preferred embodiments in conjunction with the accompanying drawings, in which:

[0021] Figure 1 is the molecular structure diagram of complex 1;

[0022] Figure 2 is the coordination environment diagram of the central Co ion of complex 1;

[0023] Figure 3 is the molecular packing diagram of complex 1;

[0024] Figure 4 Temperature-dependent magnetic susceptibility of complex 1 under 1000Oe DC field;

[0025] Figure 5 Magnetization intensity diagram of complex 1;

[0026] Figure 6 Reduced magnetization intensity diagram of complex 1;

[0027] Figure 7 Real (χ') and imaginary (χ") AC magnetic susceptibility diagrams of complex 1 at 0 Oe;

[0028] Figure 8 Real (χ') and imaginary (χ") AC magnetic susceptibility diagram of complex 1 at 1000 Oe. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and equivalent changes or modifications also fall within the scope limited by the claims of the present application.

[0030] It should be noted that all reagents in the following examples were purchased directly from the market and were of analytical grade and were not further purified before use.

[0031] Example 1: Preparation of [Co4(HL)4(N3)2][Co(HL)2]I2 (complex 1)

[0032] [Co4(HL)4(N3)2][Co(HL)2]I2 (complex 1): 32.2 mg of organic ligand H2L (0.1 mmol), 6.1 mg of Dy(CF3SO3)3 (0.01 mmol), 15.6 mg of CoI2 (0.05 mmol), and 1.3 mg of NaN3 (0.02 mmol) were weighed and dissolved in a mixed solvent of 3 mL of methanol and 3 mL of deionized water in a certain proportion, and then 10.0 mg of Et3N (0.1 mmol) was added. The mixed solution was reacted in a reactor with a polytetrafluoroethylene liner for 10 h at a reaction temperature of 80°C. Purple crystals were obtained after the reaction was completed, which was the target complex 1.

[0033] Example 2: Crystal structure determination

[0034] High-quality single crystals were selected for structural determination, and the diffraction was performed by Xcalibur, Eos CCD single crystal X-ray diffractometer, and Mo Kα rays monochromatized by graphite monochromator. Diffraction data were collected and processed using the SHELXS-2014 and SHELXL-2014 packages.

[0035] The asymmetric unit of complex 1 is Figure 1 The figure includes two parts, one of which is composed of 4 Co II Ion, 4 HL - Ligand, 2 N3 - The {Co4(HL)4} unit is composed of anions, and the other part is composed of two HL - Ligand and a Co II ions constitute the {Co(HL)} unit. Co II The coordination environment diagram is as follows Figure 2 As shown in Figure 1, Co1, Co3, and Co4 are all hexacoordinated and present an octahedral coordination configuration, where Co1 and Co4 are in the coordination environment of {O2N4}, and Co3 is in the coordination environment of {O4N2}. - They each provide a N atom (N3, N3A) and an oxygen atom (O1, O1A), and the two azido groups each provide a N atom (N9, N9A). Compared with Co1, Co2 has one less N atom provided by the azide group to participate in the coordination, presenting a five-coordinate trigonal bipyramidal coordination configuration. The four oxygen atoms (O1, O1A, O3, O3A) of the six coordinated atoms of Co3 come from four different HL -Ligand, two nitrogen atoms (N7, N7A) from two HL - Ligand. Co4 consists of two HL - Ligand coordination, each ligand provides two N atoms and one O atom to form a six-coordinated octahedral configuration. The coordination configuration of the above Co ions was verified by CShM calculation (Table 1, Table 2). The average Co-N distance in complex 1 is The average Co-O distance is The O-Co-O bond angle ranges from 77.30(18)° to 175.5(2)°, and the N-Co-N bond angle ranges from 84.4(4)° to 176.5(13)°. The stacking diagram of complex 1 is shown in Figure 3 As shown, the {Co(HL)} units are staggered with the {Co4(HL)4} units.

[0036] Table 1 CShM values ​​of Co2 in complex 1

[0037]

[0038] *PP-5=Pentagon(D 5h ); vOC-5 = Johnson square pyramid J1 (C 4v ); TBPY-5 = trigonal bipyramid (D 3h ); SPY-5 = four

[0039] Square pyramid (C 4v ); JTBPY-5 = Johnson triangular bipyramid (D 3h ).

[0040] Table 2 CShM values ​​of Co1, Co3 and Co4 in complex 1

[0041]

[0042] *HP-6=Hexagon(D 6h ); PPY-6 = pentagonal pyramid (C 5v ); OC-6 = octahedron (O h ); TPR-6 = triangular prism (D 3h );

[0043] JTBPY-5=Johnson Pentagonal Pyramid (C 5v ).

[0044] Example 3: Determination of magnetic properties

[0045] In the temperature range of 2-300K, the powder sample of complex 1 was subjected to a 1000Oe external DC electric field to test the temperature-dependent magnetic susceptibility. The results are as follows: Figure 4 The room temperature χ of complex 1 is shown in MThe T value is 10.83cm 3 Kmol -1 , higher than the five isolated Co II The theoretical value of ions (9.38 cm 3 mol -1 K), is due to the contribution of orbital angular momentum. As the temperature decreases, χ M The T value gradually decreases to 4.15cm 3 mol -1 K. The magnetization intensity diagram of complex 1 is shown in Figure 5 As shown. The magnetization value increases rapidly at low field, and there is no saturation state at 7T. The maximum value of magnetization at 2K and 7T is 8.11Nμ B The reduced magnetizations of complex 1 do not overlap, suggesting the presence of significant anisotropy and / or low excited states ( Figure 6 In the temperature range of 2-10K, the AC magnetic susceptibility of complex 1 was tested under zero external magnetic field and under an external magnetic field of 1000Oe. The test results showed that complex 1 did not show temperature and frequency dependent imaginary magnetic susceptibility signals ( Figure 7 and Figure 8 ).

Claims

1. A pentanuclear cobalt molecule-based magnet, characterized in that: The pentanuclear cobalt molecular-based magnet is an ionic molecular-based magnet, belongs to the orthorhombic crystal system, has a molecular formula of [Co4(HL)4(N3)2][Co(HL)2]I2, a space group of I222, and unit cell parameters of: α=β=γ=90°, HL is deprotonated (1S,2S)-1,2-bis(1-methyl-1H-benzo[d]imidazol-2-yl)ethane-1,2-diol).

2. A method for preparing the pentanuclear cobalt molecule-based magnet according to claim 1, characterized in that: The preparation method comprises the following steps: S1. The organic ligands H2L, Dy(CF3SO3)3, CoI2, and NaN3 are mixed and dissolved in a mixed solvent of methanol and deionized water, and then Et3N is added to obtain a mixed solution; S2. The mixed solution is heated in a reactor with a polytetrafluoroethylene liner for reaction, and the pentanuclear cobalt molecule-based magnet is obtained after the reaction is completed.

3. The preparation method according to claim 2, characterized in that: The molar ratio of organic ligands H2L, Dy(CF3SO3)3, CoI2, NaN3, and Et3N is 10:1:5:2:

10.

4. The preparation method according to claim 2, characterized in that: The volume ratio of methanol to deionized water in the mixed solvent is 2:1 to 1:

2.

5. The preparation method according to claim 4, characterized in that: The amount of the mixed solvent used for every 0.1 mmol of organic ligand H2L is 4-8 mL.

6. The preparation method according to claim 2, characterized in that: The temperature of the heating reaction is 70-90° C., and the reaction time is 8-12 hours.

7. Use of the pentanuclear cobalt molecule-based magnet according to claim 1 or the pentanuclear cobalt molecule-based magnet prepared by the preparation method according to any one of claims 2 to 6 in molecular magnetic materials or molecular memory materials.

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