Pentanuclear cobalt molecular-based magnets, their preparation methods and applications

Abstract

This invention belongs to the field of transition complex preparation technology, and discloses a pentanuclear cobalt molecular-based magnet, its preparation method, and its applications. The preparation method provided by this invention involves dissolving organic ligands H₂L, Dy(CF₃SO₃)₃, CoI₂, and NaN₃ in a mixed solution of methanol and deionized water in a certain proportion, then adding Et₃N. The mixed solution is reacted in a polytetrafluoroethylene-lined reactor for 10 hours at a reaction temperature of 80°C. Upon completion of the reaction, purple crystals are obtained. This pentanuclear cobalt complex is an ionic molecular-based magnet and can be applied to the preparation of molecular magnetic materials and molecular memory materials.

Description

Technical Field

[0001] This invention belongs to the field of transition complex preparation technology, and relates to a pentanuclear cobalt molecular-based magnet, its preparation method and its application. Background Technology

[0002] Molecular-based magnets are paramagnetic molecules that can be magnetized below a specific temperature, and they have potential applications in high-density information storage, magnetic qubits, and spintronic devices (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 necessary to weaken the quantum tunneling effect using external factors. For mononuclear transition metal molecular-based magnets, the number of coordination sites at the metal center is usually reduced to provide a relatively strong ligand field, thereby weakening the 3d orbital splitting energy. For dinuclear and multinuclear transition metal molecular-based magnets, the main focus is on exploring the influence of magnetic interactions and the coordination environment and geometry of the metal center on magnetic relaxation behavior and quantum tunneling effect, and elucidating the magnetic relaxation mechanism. Mononuclear transition molecular-based magnets have unique magnetic properties and research value, but there are still some challenges in their synthesis, preparation, and practical application. Pentanuclear transition molecular-based magnets refer to a single molecule composed of five transition metal atoms, which has specific magnetic properties. These materials typically exhibit quantum magnetic behavior at the atomic scale, which is of great significance for understanding nanoscale magnetism and developing novel magnetic materials. Due to their unique structure and magnetic properties, these molecular-based magnets have significant potential value for studying nanoscale magnetism, developing novel magnetic materials, and in the field of information storage. Summary of the Invention

[0003] The purpose of this invention is to provide a pentanuclear cobalt molecular-based magnet, its preparation method, and its application. This pentanuclear cobalt molecular-based magnet is an ionic molecular-based magnet, which enriches the structural types of transition molecular-based magnets and provides new ideas for the synthesis and application of novel transition molecular-based magnets.

[0004] The technical solution provided by this invention is as follows: A pentanuclear cobalt molecular-based magnet, wherein the pentanuclear cobalt molecular-based magnet is an ionic molecular-based magnet, belonging to the orthorhombic crystal system, with the molecular formula [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), space group I222, and cell parameters are: α=β=γ=90°,

[0005] A method for preparing a pentanuclear cobalt molecular-based magnet with ionic molecular-based magnets as described above specifically includes the following steps:

[0006] S1. 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 and reacted in a reaction vessel with a polytetrafluoroethylene liner. After the reaction is completed, the pentanuclear cobalt molecular-based magnet is obtained.

[0008] The synthetic route for pentanuclear cobalt molecular-based magnets is shown in the following formula:

[0009]

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

[0011] Furthermore, in the above preparation method, the molar ratio of 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 mixed solvent used is 4-8 mL for every 0.1 mmol of organic ligand H2L.

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

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

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

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

[0019] Compared with existing technologies, this invention utilizes the N- and O-rich chiral organic ligand H2L to successfully obtain an ionic pentanuclear cobalt molecular-based magnet via a solvothermal method. The preparation method is simple, the raw materials are readily available, and by designing the organic ligand structure to react with transition metals to form transition molecular-based magnets, the structural types of transition molecular-based magnets are enriched, providing a new direction for the exploration of their structural fields. The synthesized compound can be applied to the preparation of molecular magnetic materials or molecular memory materials, and has potential application value in fields such as high-density information storage and quantum computing. Attached Figure Description

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

[0021] Figure 1 The molecular structure diagram of coordination compound 1;

[0022] Figure 2 Coordination environment diagram of the central Co ion in complex 1;

[0023] Figure 3 The molecular packing diagram of coordination compound 1;

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

[0025] Figure 5 Magnetization diagram of complex 1;

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

[0027] Figure 7 AC magnetic susceptibility plots of the real (χ') and imaginary (χ”) parts of complex 1 at 0 Oe;

[0028] Figure 8 AC magnetic susceptibility plots of the real (χ') and imaginary (χ”) parts of complex 1 at 1000 Oe. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and equivalent alterations or modifications also fall within the scope defined by the claims of this application.

[0030] It should be noted that all reagents in the following examples were purchased directly from the market and were of analytical grade, without further purification 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): Weigh 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) and mix them in a certain proportion and dissolve them in a mixed solvent of 3 mL of methanol and 3 mL of deionized water. Then add 10.0 mg of Et3N (0.1 mmol). React the mixed solution in a reaction vessel with a polytetrafluoroethylene liner for 10 h at a reaction temperature of 80 °C. After the reaction is complete, purple crystals are obtained, which is the target complex 1.

[0033] Example 2: Crystal Structure Determination

[0034] High-quality single crystals were selected for structure determination. X-ray diffraction was performed using Xcalibur and Eos CCD single-crystal X-ray diffractometers, respectively, followed by Mo Kα rays monochromated by a graphite monochromator. Diffraction data were collected and processed using the incident light source. All calculations were performed using the SHELXS-2014 and SHELXL-2014 software packages.

[0035] The asymmetric unit of coordination compound 1 is as follows Figure 1 The diagram shows two parts, one of which consists of 4 Co II Ions, 4 HL - ligands, 2 N3 - The {Co4(HL)4} unit is composed of anions, and another part consists of two HL units. - ligand and a Co II Ions form {Co(HL)} units. Co II Coordination environment diagram as follows Figure 2 As shown, Co1, Co3, and Co4 are all six-coordinated and exhibit an octahedral coordination configuration. Co1 and Co4 have a {O2N4} coordination environment, while Co3 has a {O4N2} coordination environment. Of the six coordinating atoms in Co1, two ligands HL... - Each of the six coordinating atoms in Co3 provides one nitrogen atom (N3, N3A) and one oxygen atom (O1, O1A), while the two azide groups each provide one nitrogen atom (N9, N9A). Co2, compared to Co1, lacks the nitrogen atom provided by one azide group for coordination, exhibiting a five-coordinate trigonal bipyramidal coordination configuration. The four oxygen atoms (O1, O1A, O3, O3A) in Co3's six coordinating atoms originate from four different HL groups. -The ligands, with two nitrogen atoms (N7, N7A), originate from two HL atoms. - Ligands. Co4 consists of two HL... - Ligand coordination occurs, with each ligand providing two N atoms and one O atom, forming a six-coordinate octahedral configuration. The coordination configuration of the Co ion was verified by CShM calculations (Tables 1 and 2). The average Co-N distance in coordination compound 1 is... The average distance between Co and O 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 packing diagram of complex 1 is shown below. Figure 3 As shown, the {Co(HL)} units and {Co4(HL)4} units are arranged alternately.

[0036] Table 1. CSHM values ​​of Co2 in Complex 1

[0037]

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

[0039] Square pyramid (C 4v JTBPY-5 = Johnson's trigonometric bipyramidal (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's Pentagonal Pyramid (C 5v ).

[0044] Example 3: Measurement of Magnetic Properties

[0045] Within a temperature range of 2-300K, the magnetic susceptibility of the powder sample of coordination compound 1 was tested by applying an external DC electric field of 1000Oe at varying temperatures. The results are as follows: Figure 4 As shown. The room temperature χ² value of complex 1. MThe T value is 10.83 cm. 3 Kmol -1 , higher than five isolated Co II The theoretical value of ions (9.38 cm⁻¹) 3 mol -1 K), is due to the contribution of orbital angular momentum. As the temperature decreases, χ M The T value gradually decreased to 4.15cm 3 mol -1 The magnetization diagram of complex 1 is shown below. Figure 5 As shown, the magnetization increases rapidly at low fields and does not saturate at 7T. The maximum magnetization is 8.11 Nμ at 2K and 7T. B The lack of overlap in the reduced magnetization of complex 1 suggests the possible existence of significant anisotropy and / or low-level excited states. Figure 6 The AC magnetic susceptibility of complex 1 was tested in the temperature range of 2-10K under zero external magnetic field and under an external magnetic field of 1000 Oe. The test results showed that complex 1 did not exhibit a temperature- and frequency-dependent imaginary part magnetic susceptibility signal. Figure 7 and Figure 8 ).

Claims

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

2. A method for preparing the pentanuclear cobalt molecular-based magnet according to claim 1, characterized in that, The preparation method includes the following steps: S1. 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 and reacted in a reaction vessel with a polytetrafluoroethylene liner. After the reaction is completed, the pentanuclear cobalt molecular-based magnet is obtained.

3. The preparation method according to claim 2, characterized in that, The molar ratio of the 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 volume of mixed solvent used is 4-8 mL for every 0.1 mmol of organic ligand H2L.

6. The preparation method according to claim 2, characterized in that, The heating reaction is carried out at a temperature of 70-90℃ for 8-12 hours.

7. The application of the pentanuclear cobalt molecular-based magnet of claim 1 or the pentanuclear cobalt molecular-based magnet prepared by any one of claims 2-6 in molecular magnetic materials or molecular memory materials.

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