X-ray excitation generated free radical dysprosium-based monomolecular magnets and synthesis method thereof

Abstract

The present application relates to a kind of X-ray excitation generation free radical dysprosium-based monomolecular magnet and its synthesis method, magnet chemical formula is: [Dy2 (Cy3PO) 4 (H2O) 8 (C5O5) ]Cl4·2 (Cy3PO), with dysprosium chloride hexahydrate as metal salt, tricyclohexyl phosphine oxide is axial ligand, ketonic acid is bridging ligand, methanol is solvent, is prepared by stirring, separation and solid washing.The dysprosium-based monomolecular magnet generates free radical after X-ray irradiation at room temperature, has photochromic phenomenon, can be directly visually detected X-ray by photochromic mechanism;At the same time, the generation of free radical can make this monomolecular magnet produce performance response: irradiation can close its monomolecular magnet behavior and produce new peak on ultraviolet-visible spectrum while improving single crystal phase transition temperature.This material will provide experience for the research of regulating material performance, help to expand the application of monomolecular magnet.

Description

Technical Field

[0001] This invention belongs to the field of functional material preparation technology, and in particular relates to a dysprosium-based single-molecule magnet that generates free radicals by X-ray excitation and its synthesis method. Background Technology

[0002] Molecular-based magnetic materials are a class of magnetic compounds formed by the spontaneous and controlled assembly of free radicals or paramagnetic ions (including transition metal ions and rare earth metal ions) and organic ligands through chemical methods. Compared to traditional magnets, they offer advantages such as lower density, higher transparency, better solubility, easier processing, and better controllability, making them promising for applications in aerospace materials, microwave materials, information recording materials, and opto-magnetic and electromagnetic materials. Single-molecule magnets, as an important research area of ​​molecular-based magnetic materials, possess advantages such as nanoscale size, easy dispersion, and high magnetic density, and can be used to develop information storage materials with higher density, quantum computers, and molecular spin devices.

[0003] Due to the unique magnetic properties of the 4f electrons in rare earth ions, constructing single-molecule magnets using lanthanide metal ions is currently a significant direction in molecular magnetism. Lanthanide ions have a large number of unpaired electrons and stronger spin-orbit coupling, while dysprosium ions, as Kramer ions, produce bistable ground states in dysprosium-based single-molecule magnets. Therefore, research on dysprosium-based single-molecule magnets is relatively in-depth. Multifunctional single-molecule magnets that combine multiple physical properties at the molecular level have immense research value and are excellent candidates for next-generation intelligent devices that can simultaneously perform multiple tasks. However, examples of combining multiple physical properties into a single dysprosium-based single-molecule magnet are currently scarce. On the other hand, the generation of free radicals requires complex reaction conditions, and free radicals are highly reactive, making it difficult to obtain air-stable free radical complexes in situ at room temperature. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a dysprosium-based single-molecule magnet that generates free radicals through X-ray excitation and its synthesis method.

[0005] The technical solution adopted in this invention is: a dysprosium-based single-molecule magnet, with the chemical formula:

[0006] [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO); where Cy3PO is tricyclohexylphosphorus oxide, and C5O5... － It is a keto acid anion;

[0007] The central ion Dy of dysprosium-based single-molecule magnet 3+ In a seven-coordinated environment, the seven coordinating atoms are derived from oxygen atoms on two ligands, oxygen atoms from four water molecules, and oxygen atoms from a keto acid anion. The two Dy atoms...3+ They are connected by keto acid anion bridges.

[0008] Preferably, the dysprosium-based single-molecule magnet belongs to the triclinic crystal system and has a test temperature of 300K. Space group, α=95.1650(10)°, β=98.8880(10)°, γ=99.0040(10)°; the space group is P1 at the test temperature of 80K. α=94.5990(10)°, β=98.7580(10)°, γ=100.4260(10)°.

[0009] Preferably, stable free radicals are generated in situ after X-ray irradiation at room temperature, resulting in photochromic phenomena.

[0010] A method for synthesizing dysprosium-based single-molecule magnets, characterized by using dysprosium hexahydrate as a metal salt, tricyclohexylphosphoric acid as an axial ligand, ketone acid as a bridging ligand, and methanol as a solvent for synthesis.

[0011] Preferably, the specific steps are as follows:

[0012] A mixture of DyCl3·6H2O, Cy3PO and ketone acid in a molar ratio of 5:10:2 was placed in a container, methanol solvent was added, and the mixture was stirred at 50-65℃ for 0.5-3 hours according to the mass-to-volume ratio of the total mass of the DyCl3·6H2O, Cy3PO and ketone acid mixture to the solvent of 12.8 mg: 1-2 mL.

[0013] The mixed solution was left to stand at room temperature to obtain yellow, clustered dysprosium monomolecular magnets.

[0014] Preferably, the solvent is evaporated to 5-10 ml before standing, and then left to stand for 3-15 days.

[0015] Preferably, the crystal is rinsed with ether before the solvent has completely evaporated, and any remaining solvent on the crystal surface is absorbed.

[0016] Application of dysprosium-based single-molecule magnets in X-ray detection.

[0017] Application of dysprosium-based single-molecule magnets in molecular switches.

[0018] The advantages and positive effects of this invention are: a Dy-based single-molecule magnet is prepared, which generates stable free radicals in situ after being irradiated with X-rays at room temperature, exhibiting photochromic phenomena; based on the property that this material can utilize X-rays to convert into free radicals at room temperature, X-rays can be directly detected visually through the photochromic mechanism;

[0019] Meanwhile, the generation of photoradicals can induce a performance response in this single-molecule magnet. Irradiation can shut down its single-molecule magnet behavior and generate new peaks in the ultraviolet-visible spectrum, and can also increase the phase transition temperature of the single crystal. The changes in magnetic properties are particularly important. This material will provide experience for the research on the rational design and control of material properties, and will help expand the application of single-molecule magnets.

[0020] The preparation process provided by this invention is safe, simple, highly controllable, and reproducible. The prepared single crystals are large in size, and have high purity and yield. Attached Figure Description

[0021] Figure 1 The structure diagrams of [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO) obtained by single-crystal diffraction analysis are shown; (a) is the structure diagram measured at 80K, and (b) is the structure diagram measured at 300K.

[0022] Figure 2 Experimental electron paramagnetic resonance spectra of [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO) before and after X-ray irradiation;

[0023] Figure 3 The UV-Vis spectra of [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO) before and after X-ray irradiation are experimental figures.

[0024] Figure 4 Experimental diagrams of AC magnetic susceptibility of [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO) before and after X-ray irradiation;

[0025] Figure 5 Experimental diagrams showing the dielectric constant of [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO) before and after X-ray irradiation;

[0026] Figure 6 The photochromic phenomenon of [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO) after X-ray irradiation. Detailed Implementation

[0027] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] This invention relates to a dysprosium-based single-molecule magnet that generates free radicals through X-ray excitation and its synthesis method. This multifunctional dysprosium-based single-molecule magnet possesses various physical properties, solving the problem of difficulty in obtaining air-stable free radical complexes in situ at room temperature. The chemical formula of the dysprosium-based single-molecule magnet is represented as follows:

[0029] [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO), where Cy3PO is tricyclohexylphosphine oxide and C5O5 is a keto acid anion;

[0030] The central ion Dy of a dysprosium monomolecular magnet 3+ In a seven-coordinated environment, two Dy 3+ They are connected by a keto acid anion bridge. The seven coordinating atoms originate from oxygen atoms on two ligands, oxygen atoms from four water molecules, and an oxygen atom from the keto acid anion. The structure is as follows: Figure 1 As shown, for the sake of simplicity, the hydrogen atom is in Figure 1 Not displayed.

[0031] Dysprosium single-molecule magnets belong to the triclinic crystal system and crystallize at 300K. Space group, α=95.1650(10)°, β=98.8880(10)°, γ=99.0040(10)°. Crystallizes at 80K in space group P1. α=94.5990(10)°, β=98.7580(10)°, γ=100.4260(10)°.

[0032] This dysprosium single-molecule magnet generates free radicals in situ upon X-ray irradiation. The excited free radicals are air-stable, and complete quenching of the free radicals requires more than 10 days. X-rays can be directly detected visually through photochromism, and the generation of free radicals can affect the magnetic and optical properties of the single-molecule magnet, providing a new approach to control the performance of single-molecule magnets and realizing their multifunctionality.

[0033] This invention also relates to a method for synthesizing a dysprosium-based single-molecule magnet that generates free radicals through X-ray excitation. The method uses dysprosium hexahydrate as a metal salt, Cy3PO as a ligand, and methanol as a solvent. The synthesis steps are as follows:

[0034] Step 1. Place the mixture of DyCl3·6H2O, Cy3PO and ketone acid in a container with a molar ratio of 5:10:2, and add methanol solvent. Mix the mixture at a mass-to-volume ratio of 12.8 mg to 1-2 mL of solvent according to the total mass of the mixture of DyCl3·6H2O, Cy3PO and ketone acid. Stir at 50-65℃ for 0.5-3 h.

[0035] Step 2. Let the above mixed solution stand at room temperature to obtain yellow cluster-shaped crystals—dysprosium-based single-molecule magnets;

[0036] To accelerate the reaction, the mixture can be evaporated to 5-15 ml before settling, and then allowed to stand at room temperature for 3-15 days to obtain yellow clustered crystals. This operation is to avoid the evaporation process being too long, which makes it easier for impurities (salts or other complexes) to precipitate. In some embodiments of the present invention, the crystals are rinsed with ether before the solvent has completely evaporated, and the remaining solvent on the crystal surface is blotted dry with filter paper. The resulting crystals are then collected. This method can be used to purify the obtained crystals.

[0037] The aforementioned preparation process is safe, simple, highly controllable, and reproducible, producing crystals with relatively large sizes (up to millimeters), high purity, and high yield. Large-size single crystals offer greater operability, and their synthesis facilitates in-depth research into physical properties and the deviceization of materials. The prepared dysprosium-based single-molecule magnets can be applied to high-density information storage materials, qubits, sensing, recognition, and molecular spin devices. Furthermore, the dysprosium-based single-molecule magnets prepared by this method can generate free radicals through X-ray irradiation, thereby shutting down the single-molecule magnet behavior, allowing them to function as molecular switches. This switching behavior can be applied to recognition and sensing, and provides a research foundation for applications in high-density information storage and quantum computing, possessing significant scientific value. Simultaneously, by externally stimulating and regulating the physical properties of the single-molecule magnets, increasing the phase transition temperature of the single crystal can bring the material's application temperature closer to room temperature. Phase transitions occurring near room temperature allow for structural switching, thereby altering the material's physical properties.

[0038] The present invention will now be described with reference to the accompanying drawings. Experimental methods not specifically described in terms of operation steps are performed in accordance with the corresponding product manuals. Unless otherwise specified, the instruments, reagents, and consumables used in the embodiments can be purchased from commercial companies.

[0039] Example 1:

[0040] A mixture of 0.25 mmol of DyCl3·6H2O, 0.5 mmol of tricyclohexylphosphine oxide, and 0.1 mmol of ketone acid was added to a beaker, followed by 20 mL of methanol. The mixture was stirred at 60 °C for 2 h. The solution was evaporated to 5 mL, and then allowed to stand at room temperature for 5 days to obtain yellow, clustered crystals—dysprosium-based monomolecular magnets. The crystals were rinsed with diethyl ether before the solvent completely evaporated, and the remaining solvent on the crystal surface was blotted dry with filter paper to purify the product. The yield was calculated to be 82% based on metallic Dy.

[0041] Example 2:

[0042] A mixture of 0.25 mmol of DyCl3·6H2O, 0.5 mmol of tricyclohexylphosphine oxide, and 0.1 mmol of ketone acid was added to a beaker, followed by 40 mL of methanol. The mixture was stirred at 50 °C for 3 h. The solution was evaporated to 12 mL, and then allowed to stand at room temperature for 10 days to obtain yellow, clustered crystals—dysprosium-based monomolecular magnets. The crystals were rinsed with diethyl ether before the solvent completely evaporated, and the remaining solvent on the crystal surface was blotted dry with filter paper to purify the product. The yield was calculated to be 80% based on metallic Dy.

[0043] Example 3:

[0044] A mixture of 0.5 mmol of DyCl3·6H2O, 1 mmol of tricyclohexylphosphine oxide, and 0.2 mmol of ketone acid was added to a beaker, followed by 40 mL of methanol. The mixture was stirred at 65 °C for 2 h. The solution was evaporated to 10 mL, and then allowed to stand at room temperature for 7 days to obtain yellow, clustered crystals—dysprosium-based monomolecular magnets. The crystals were rinsed with diethyl ether before the solvent completely evaporated, and the remaining solvent on the crystal surface was blotted dry with filter paper to purify the product. The yield was calculated to be 79% based on metallic Dy.

[0045] Example 4:

[0046] A mixture of 0.25 mmol of DyCl3·6H2O, 0.5 mmol of tricyclohexylphosphine oxide, and 0.1 mmol of ketone acid was added to a beaker, followed by 40 mL of methanol. The mixture was stirred at 65 °C for 0.5 h. The solution was evaporated to 5 mL, and then allowed to stand at room temperature for 3 days to obtain yellow, clustered crystals—dysprosium-based monomolecular magnets. The crystals were rinsed with diethyl ether before the solvent completely evaporated, and the remaining solvent on the crystal surface was blotted dry with filter paper to purify the product. The yield was calculated to be 84% based on metallic Dy.

[0047] Example 5: Characterization of the properties of the dysprosium-based single-molecule magnet for X-ray excited free radicals

[0048] The dysprosium-based single-molecule magnet prepared in Example 1 was characterized.

[0049] 5.1 Structural Measurement

[0050] Crystal structure determination was performed at 300 K using a ROD Synergy Custom system HyPix-Arc 150 X-ray single-crystal diffractometer, employing graphite-monochromated Cu-K. α ray As the incident radiation source, with Diffraction points were collected using a scanning method, and the unit cell parameters were obtained after least squares correction. Absorption effects were corrected using a multi-scan method. The preliminary structure was obtained directly using SHELXT 2018 / 2 (Sheldrick, 2018), and then refined using Olex2 software with SHELXL2016 / 4 (Sheldrick, 2015) as the program. All H atoms were synthesized using difference Fourier analysis and their positions were determined by ideality calculations. Crystal structure determination was performed at 80 K using an XtaLAB Synergy R, HyPix X-ray single-crystal diffractometer, employing graphite-monochromated Cu-K diffractometers. α ray As the incident radiation source, with Diffraction points were collected using a scanning method, and the unit cell parameters were obtained after least squares correction. Absorption effects were corrected using a multi-scan method. The preliminary structure was obtained directly using SHELXT 2018 / 2 (Sheldrick, 2018), and then refined using Olex2 software with SHELXL 2018 / 3 (Sheldrick, 2015) as the program. All H atoms were synthesized using a difference Fourier method and their positions were determined by ideal position calculations. Detailed crystal measurement data are shown in Table 1, and the structure is shown in [Table missing]. Figure 1 .

[0051] Table 1 Crystallographic data of the coordination compounds

[0052]

[0053]

[0054] Figure 1 The structural diagram shows that the central ion Dy of the dysprosium-based single-molecule magnet 3+ In a seven-coordinated environment, the seven coordinating atoms are derived from oxygen atoms on two ligands, oxygen atoms from four water molecules, and oxygen atoms from a keto acid anion. The two Dy atoms... 3+ The crystals are connected by ketone anions. At 300 K, the crystals crystallize in the P1 space group, and at 80 K, they crystallize in the P1 space group. Between 80 and 300 K, the crystals undergo a phase transformation.

[0055] 5.2 Electron Paramagnetic Resonance Spectroscopy Test

[0056] Electron paramagnetic resonance (EPR) spectroscopy was performed on the dysprosium-based single-molecule magnet prepared in Example 1. The experimental results of the change in the EPR spectrum of the single-molecule magnet at room temperature with X-ray irradiation time are as follows: Figure 2As shown, the original sample did not show an EPR signal, but a distinct single-peak radical signal was observed after X-ray irradiation, and this signal increased with the extension of X-ray irradiation time. This demonstrates that stable radicals are generated in situ by dysprosium-based single-molecule magnets after X-ray irradiation.

[0057] 5.3 Ultraviolet-Visible Spectroscopy Test

[0058] The experiment shows the change of the UV-Vis spectrum of the dysprosium-based single-molecule magnet at room temperature with X-ray irradiation time as follows: Figure 3 As shown, the original sample had no absorption band in the 450–550 nm range, but an absorption band was observed after X-ray irradiation. This absorption band increased with the duration of X-ray irradiation, and its appearance was caused by free radicals generated by X-rays.

[0059] 5.4 Characterization of Magnetic Properties

[0060] The AC magnetic susceptibility curve of this dysprosium-based single-molecule magnet in the 10-996 Hz range is as follows: Figure 4 As shown, (a) and (b) are the real and imaginary parts of the AC magnetic susceptibility before illumination, respectively, and (c) and (d) are the real and imaginary parts of the AC magnetic susceptibility after illumination, respectively. After X-ray irradiation, the peak value of the magnetic susceptibility curve disappears, and the frequency dependence is lost. This clarifies that X-ray irradiation of free radicals can shut down the single-molecule magnet behavior of dysprosium-based single-molecule magnets.

[0061] 5.5 Dielectric constant test

[0062] The dielectric constant-temperature curve of this dysprosium single-molecule magnet is as follows: Figure 5 As shown, the dielectric constant peaks at 265K before illumination, indicating a phase transition around 265K. Similarly, the phase transition temperature after illumination is around 286K, which is consistent with... Figure 1 The measured phase transitions correspond to those of the single-crystal structure. This indicates that X-ray irradiation affects the phase transition temperature of single crystals.

[0063] 5.6 Effects of X-ray irradiation

[0064] The prepared dysprosium-based single-molecule magnet was irradiated with X-rays from... Figure 6 As can be seen, before irradiation (left figure), the dysprosium-based single-molecule magnet is yellow, and after irradiation (right figure), the dysprosium-based single-molecule magnet is orange, indicating that the dysprosium-based single-molecule magnet has a photochromic phenomenon.

[0065] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A dysprosium-based single-molecule magnet, characterized in that: The chemical formula is represented as: [Dy2(Cy3PO)4(H2O)8(C5O5)]Cl4·2(Cy3PO); Cy3PO is tricyclohexylphosphorus oxide, C5O5 － It is a keto acid anion; The central ion Dy of dysprosium-based single-molecule magnet 3+ It is in a seven-coordinate environment, with its seven coordinating atoms coming from oxygen atoms on two ligands, oxygen atoms from four water molecules, and an oxygen atom from a keto acid anion. The two Dy atoms... 3+ They are connected by keto acid anion bridges.

2. The dysprosium-based single-molecule magnet according to claim 1, characterized in that: Dysprosium-based single-molecule magnets belong to the triclinic crystal system and are tested at 300K. Space group, α=95.1650(10)°, β=98.8880(10)°, γ=99.0040(10)°; the space group is P1 at the test temperature of 80K. α=94.5990(10)°, β=98.7580(10)°, γ=100.4260(10)°.

3. The dysprosium-based single-molecule magnet according to claim 1 or 2, characterized in that: Stable free radicals are generated in situ after X-ray irradiation at room temperature, resulting in photochromism.

4. The method for synthesizing the dysprosium-based single-molecule magnet according to any one of claims 1-3, characterized in that: The synthesis was carried out using dysprosium hexahydrate as the metal salt, tricyclohexylphosphoric acid as the axial ligand, ketone acid as the bridging ligand, and methanol as the solvent.

5. The method for synthesizing dysprosium-based single-molecule magnets according to claim 4, characterized in that: The specific steps are as follows: A mixture of DyCl3·6H2O, Cy3PO, and ketone acid in a molar ratio of 5:10:2 is placed in a container. Methanol solvent is added, and the mixture is stirred at a ratio of 12.8 mg:1-2 mL (total mass of the DyCl3·6H2O, Cy3PO, and ketone acid mixture to the solvent). The mixed solution was left to stand at room temperature to obtain yellow, clustered dysprosium monomolecular magnets.

6. The method for synthesizing dysprosium-based single-molecule magnets according to claim 5, characterized in that: Before allowing it to stand, evaporate the solvent to 5-10 ml and then let it stand for 3-15 days.

7. The method for synthesizing dysprosium-based single-molecule magnets according to claim 5, characterized in that: Rinse the crystals with ether before the solvent has completely evaporated, and blot off any remaining solvent from the crystal surface.

8. The application of the dysprosium-based single-molecule magnet according to any one of claims 1-3 in the detection of X-rays.

9. The application of the dysprosium-based single-molecule magnet according to any one of claims 1-3 in molecular switches.

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