Cobalt complexes with ferromagnetic interactions, methods of making and using the same

Abstract

The application belongs to the technical field of transition metal coordination chemistry, and relates to a cobalt complex with ferromagnetic interaction and a preparation method and application thereof. The molecular formula of the cobalt complex is {Co(bim)4[N(CN)2]2} n : wherein bim is 1-allyl imidazole. n The synthesis method of the {Co(bim)4[N(CN)2]2} n includes the following steps: dissolving anhydrous cobalt chloride in anhydrous methanol, adding a bim ligand, stirring, dissolving sodium dicyanamide in water and then adding the sodium dicyanamide into the above solution, filtering after sufficient reaction, and obtaining a red solution. The solution is left to volatilize in air, and the cobalt complex with ferromagnetic interaction can be obtained after several days. The preparation process is safe and simple, controllable and reproducible, and the prepared complex has good stability and high purity. The cobalt ions in the complex have ferromagnetic interaction, and the complex can be used as a molecular-based magnetic material in the field of new high-density information storage equipment.

Description

Technical Field

[0001] This invention belongs to the technical field of transition metal coordination functional materials, and relates to a cobalt coordination compound with ferromagnetic interaction, its preparation method and application. Background Technology

[0002] Coordination polymers, an important form of supramolecular polymers, are built upon a precise self-assembly process between metal ions and organic ligands. Coordination polymers, with their highly ordered, infinite network structures, represent one concrete application of crystal engineering in supramolecular compounds. Coordination polymers possess novel structures and hold broad application prospects. [2] This has aroused great interest among many researchers.

[0003] Coordination polymers, as a special class of compounds, have metal centers figuratively called "nodes," a term that highlights the central role of the metal center in the structure of coordination polymers. Transition metal ions, due to their unique electronic structures, are often used as nodes in coordination polymers. The d orbitals of their electron-filled portions exhibit different orbital coupling modes under different coordination environments, which makes it possible to design coordination polymers with specific properties and applications. By adjusting the type of transition metal ion and the coordination environment, the properties of coordination polymers can be precisely controlled. Different types of electronic structures are an important factor in their ability to possess a variety of different coordination geometries.

[0004] Coordination polymers, due to their unique structure and composition, exhibit diverse magnetic properties, which hold significant research value and application prospects in materials science and physics. Magnetism is the macroscopic manifestation of the magnetic moments of atoms or ions in solid matter, typically encompassing different magnetic properties such as ferromagnetism, ferrimagnetism, and ferrimagnetism. Ferromagnetism refers to the tendency of adjacent atoms or ions in a substance to align in the same direction due to their interactions. Under the influence of an external magnetic field, this directional alignment of magnetic moments is enhanced until saturation is reached. To achieve efficient magnetism, metal ions can form shorter bonds with small ligands (such as cyano or azide groups), thereby enhancing the magnetic coupling between metal ions. Summary of the Invention

[0005] The purpose of this invention is to provide a cobalt complex with ferromagnetic interaction, its preparation method and application. The complex is simple and easy to synthesize and can exist stably in air.

[0006] In a first aspect, the present invention provides a cobalt complex having ferromagnetic interactions, having the molecular formula {Co(bim)4[N(CN)2]2} nWhere bim is 1-allylimidazolium; the crystallographic parameters of the cobalt complex are: the crystal belongs to the monoclinic crystal system, the space group is P21 / n, and the unit cell parameters are... α=90°, β=103.3570(10)°, γ=90°; in each unit of the cobalt complex, the cobalt ion is associated with 4 bim and 2 [N(CN)2]2 - Ions coordinate to form a six-coordinate configuration; the cobalt ions in each unit of the cobalt complex have a distorted octahedral configuration.

[0007] A second aspect of the present invention provides a method for preparing the above-mentioned cobalt complex with ferromagnetic interaction, the method comprising the following steps:

[0008] S1. Dissolve anhydrous cobalt chloride in anhydrous methanol, add BIM ligand, stir, and obtain the reaction solution;

[0009] S2. Sodium dicyandiamide is dissolved in water and added to the reaction solution to carry out the reaction. After the reaction is completed, the solution is filtered to obtain a red solution.

[0010] S3. Allow the red solution to stand in air to evaporate, thereby obtaining the cobalt complex with ferromagnetic interaction.

[0011] In some embodiments, in step S2 of the preparation method, the reaction temperature is room temperature.

[0012] In some embodiments, in step S3 of the preparation method, the settling time is 7-14 days.

[0013] In some embodiments, in the preparation method, the molar ratio of CoCl2 to bim is 1:2, and every 0.5 mmol of CoCl2 corresponds to 2.0-2.5 mmol of sodium dicyandiamide.

[0014] In some embodiments, in the preparation method, each 0.5 mmol of CoCl2 corresponds to 10-15 mL of anhydrous methanol.

[0015] In some embodiments, in the preparation method, every 2 mmol of sodium dicyandiamide corresponds to 2 mL of water.

[0016] In the complex prepared by this invention, cobalt ions are located in an octahedral coordination environment and exhibit ferromagnetic interactions.

[0017] In a third aspect, the present invention provides the application of the cobalt complex described above or the cobalt complex prepared by the above preparation method in the preparation of molecular-based magnetic materials.

[0018] In a fourth aspect, the present invention provides the application of the cobalt complex described above or the cobalt complex prepared by the above preparation method in high-density information storage materials.

[0019] Compared with existing technologies, the preparation method of this invention is simple to operate, has good controllability and high reproducibility. The resulting complex is stable in room temperature air, has high purity, and exhibits ferromagnetic interaction. It can be widely used in the preparation of molecular-based magnetic materials and high-density information storage materials. Attached Figure Description

[0020] Figure 1 The cobalt complex {Co(bim)4[N(CN)2]2} provided by this invention n Coordination environment diagram of cobalt ions.

[0021] Figure 2 The cobalt complex {Co(bim)4[N(CN)2]2} provided by this invention n The stacking structure diagram.

[0022] Figure 3 The cobalt complex {Co(bim)4[N(CN)2]2} provided by this invention n The temperature-dependent magnetic susceptibility test diagram. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] All reagents used in this invention are commercially available and of analytical grade.

[0025] Example 1

[0026] Dissolve 0.5 mmol of CoCl₂ in 10 ml of anhydrous methanol, then add 1 mmol of bimethylene glycol and stir. Weigh 2 mmol of sodium dicyandiamide, dissolve it in 2 ml of water, and quickly add it to the above solution. After reacting for 6 hours, filter to obtain a clear, pinkish-red filtrate. Expose the filtrate to air and allow it to evaporate for one week to obtain purplish-red blocky crystals, namely the cobalt complex {Co(bim)₄[N(CN)₂]₂}. n The yield was 61%.

[0027] Example 2

[0028] Dissolve 0.5 mmol of CoCl₂ in 10 mL of anhydrous methanol, then add 1 mmol of bimethylene glycol and stir. Weigh 2.5 mmol of sodium dicyandiamide, dissolve it in 2.5 mL of water, and quickly add it to the above solution. After reacting for 6 hours, filter to obtain a clear, pinkish-red filtrate. Expose the filtrate to air and allow it to evaporate for 10 days to obtain purplish-red blocky crystals, with a yield of 60%.

[0029] Example 3

[0030] Dissolve 0.5 mmol of CoCl₂ in 15 ml of anhydrous methanol, then add 1 mmol of bimethylene glycol and stir. Weigh 2 mmol of sodium dicyandiamide, dissolve it in 2 ml of water, and quickly add it to the above solution. After reacting for 6 hours, filter to obtain a clear, pinkish-red filtrate. Expose the filtrate to air and allow it to evaporate for two weeks to obtain purplish-red crystals, with a yield of 60%.

[0031] The cobalt complex {Co(bim)4[N(CN)2]2} prepared in Example 1 of this invention n The following measurements were performed on the sample:

[0032] (1) Crystal structure determination

[0033] A single crystal of appropriate size was selected under a microscope, and its structure was tested at room temperature using a Bruker SMARTApex IICCD single crystal analyzer with a graphite-monochromatic molybdenum target. Data were collected and the unit cell determined using the APEXII program. The structural data were normalized and absorption corrected using the SAINT and SADABS programs. The structure was analyzed using the SHELLT L-97 program. The coordinates of all non-hydrogen atoms were obtained by difference Fourier synthesis, and the atomic coordinates and anisotropic temperature factor were corrected using the full matrix least squares method. All hydrogen atoms were analyzed using theoretical hydrogenation. Figure 1 The diagram shows a cobalt complex {Co(bim)4[N(CN)2]2}. n Coordination environment diagram of cobalt ions. Figure 1 The structural diagram proves that the cobalt ion is located in an octahedral coordination environment. Figure 2 The diagram shows a cobalt complex {Co(bim)4[N(CN)2]2}. n The packing structure diagram is shown in Table 1. Crystallographic data are shown in Table 2, and coordination bond lengths are shown in Table 2.

[0034] Table 1: Cobalt complexes {Co(bim)4[N(CN)2]2} n Crystallographic data

[0035]

[0036]

[0037] Table 2: Cobalt complexes {Co(bim)4[N(CN)2]2} n Coordination bond length and bond angle data

[0038] <![CDATA[Co1-N2 1 ]]> 2.1171(14) Co1-N2 2.1171(14) <![CDATA[Co1-N5 2 ]]> 2.1562(16) <![CDATA[Co1-N5 3 ]]> 2.1562(16) Co1-N3 2.1429(15) <![CDATA[Co1-N3 1 ]]> 2.1429(15) <![CDATA[N2 1 -Co1-N2]]> 180.0 <![CDATA[N2 1 -Co1-N3]]> 88.57(6) N3-Co1-N2 91.43(6) <![CDATA[N2 1 -Co1-N3 1 ]]> 91.43(6) <![CDATA[N2-Co1-N3 1 ]]> 88.57(6) <![CDATA[N2-Co1-N5 2 ]]> 89.98(6) <![CDATA[N2 1 -Co1-N5 2 ]]> 90.02(6) <![CDATA[N2 1 -Co1-N5 3 ]]> 89.98(6) <![CDATA[N2-Co1-N5 3 ]]> 90.02(6) <![CDATA[N3 1 -Co1-N3]]> 180.0 <![CDATA[N3 1 -Co1-N5 2 ]]> 88.89(7) <![CDATA[N3 1 -Co1-N5 3 ]]> 91.11(7) <![CDATA[N3-Co1-N5 3 ]]> 88.89(7) <![CDATA[N3-Co1-N5 2 ]]> 91.11(7) <![CDATA[N5 2 -Co1-N5 3 ]]> 180.0

[0039] Each cobalt ion is associated with four bim ligands and two [N(CN)2]2. - Coordination is performed to form an octahedral coordination configuration, which is calculated by Shape software (Table 3).

[0040] Table 3: Cobalt complexes {Co(bim)4[N(CN)2]2} n CSHM value

[0041] configuration CShM value HP-6 (Hexagonal) 32.366 PPY-6 (Pentagonal Pyramid) 29.829 OC-6 (octahedral) 0.022 TPR-6 (Triangular Prism) 16.456 JPPY-6 (Pentagonal Pyramid) 33.267

[0042] (2) Characterization of magnetic properties

[0043] Magnetic measurements were performed using a Quantum Design MPMS SQUID VSM magnetic measurement system. The DC magnetic susceptibility was measured at a temperature of 2.0–300 K and a magnetic field of 1000 Oe.

[0044] like Figure 3 As shown, at 300K, the χ of the complex M The T value is 3.01cm 3 K mol -1 It is much larger than the χ² value when only the spin of the Co(II) ion is considered. M Theoretical value of T (1.875cm) 3 Kmol -1 This indicates the presence of a large orbital angular momentum in the complex, which increases its magnetic anisotropy through orbital-rotor coupling. As the temperature decreases, the χ² of the complex... M The T value gradually decreases. When the temperature drops to around 50K, χ... M The sudden increase in the T value indicates the presence of ferromagnetic interactions within the complex. When the temperature drops to 30 K, χ... M The T value continued to decrease until the temperature dropped to 2.5 K, at which point the χ² of the complex... M The T-value dropped to its lowest value, which was 1.87 cm. 3 K mol -1 .

[0045] In summary, the cobalt complex prepared by this invention exhibits ferromagnetic interactions and can be used as a molecular-based magnetic material in high-density information storage devices.

[0046] While some embodiments of the present general inventive concept have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A cobalt complex with ferromagnetic interactions, having the molecular formula {Co(bim)4[N(CN)2]2} n Where bim is 1-allylimidazolium; the crystallographic parameters of the cobalt complex are: the crystal belongs to the monoclinic crystal system, the space group is P21 / n, and the unit cell parameters are... α=90°, β=103.3570(10)°, γ=90°; In each unit of the cobalt complex, cobalt ions are respectively combined with 4 bim and 2 [N(CN)2]2 - Ions coordinate to form a six-coordinate configuration; The cobalt ions in each unit of the cobalt complex have a distorted octahedral configuration.

2. A method for preparing the cobalt complex according to claim 1, characterized in that, The preparation method includes the following steps: S1. Dissolve anhydrous cobalt chloride in anhydrous methanol, add BIM ligand, stir, and obtain the reaction solution; S2. Dissolve sodium dicyandiamide in water and add it to the reaction solution to carry out the reaction. After the reaction is completed, filter to obtain a red solution. S3. Allow the red solution to stand in air to evaporate, thereby obtaining the cobalt complex with ferromagnetic interaction.

3. The preparation method according to claim 2, characterized in that, In step S2, the reaction temperature is room temperature.

4. The preparation method according to claim 2, characterized in that, In step S3, the settling time is 7-14 days.

5. The preparation method according to claim 2, characterized in that, The molar ratio of CoCl2 to bim is 1:2, and every 0.5 mmol of CoCl2 corresponds to 2.0-2.5 mmol of sodium dicyandiamide.

6. The preparation method according to claim 2, characterized in that, Each 0.5 mmol of CoCl2 corresponds to 10-15 mL of anhydrous methanol.

7. The preparation method according to claim 6, characterized in that, Each 2 mmol of sodium dicyandiamide corresponds to 2 mL of water.

8. The cobalt complex according to claim 1 or the cobalt complex prepared by any one of claims 2-7 is used in the preparation of molecular-based magnetic materials.

9. The application of the cobalt complex according to claim 1 or the cobalt complex prepared by any one of claims 2-7 in high-density information storage materials.

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