Preparation method and application of dysprosium-based single-molecule magnet with redox activity

Abstract

The invention discloses a preparation method and application of a dysprosium-based single-molecule magnet with redox activity, wherein the structural formula of the dysprosium-based single-molecule magnet is [(bbpen-Cl)Dy(μ-CA)Dy(bbpen-Cl)]·MeCN. The invention selects a high-performance dysprosium-based single-ion magnet primitive and a chloranilic acid bridging ligand to construct a zero-dimensional binuclear dysprosium-based single-molecule magnet. The classic pentagonal bipyramidal single-ion magnet primitive [Dy III (bbpen‑Cl)] + The presence of enables the complex to maintain the significant magnetic anisotropy of the dysprosium ion, and the selected chloranilic acid bridging ligand can form a delocalized π radical regardless of oxidation or reduction, so the obtained product has both magnetic properties and redox activity. The construction and preparation of the redox-active dysprosium-based single-molecule magnet of the present invention also provides a new synthetic idea and method for obtaining such complexes.

Description

Technical Field

[0001] The present invention relates to the technical field of molecule-based magnetic materials, and in particular to a preparation method and application of a dysprosium-based single-molecule magnet with redox activity. Background Art

[0002] Single-molecule magnets are molecular-based magnetic materials composed of a core containing organic ligands and paramagnetic metal ions. Their magnetism originates from the electronic structure within the molecule and exhibits slow magnetic relaxation at low temperatures. This material has important applications in magnetic storage, quantum information processing, and magnetic sensors. In order to achieve magnetic operation at room temperature, it is crucial to improve the performance of single-molecule magnets, among which the magnetic blocking temperature T B The spin flip effective energy barrier Ueff is the key parameter. The performance of single-molecule magnets can be effectively regulated by designing and modifying ligands, including strategies such as regulating the redox state of ligands, substituents and end group modifications.

[0003] Quinone acid ligands and their derivatives are widely used in the construction of transition metal complexes as an important bridging ligand. These ligands have good redox activity and can achieve subtle electronic structure regulation through external redox induction, thereby affecting their chemical and physical properties. In particular, quinone acid ligands form delocalized π radicals during the redox process, form strong exchange coupling with metal ions, and achieve effective electron transfer. At present, there are relatively few studies on the application of quinone acid bridging ligands in rare earth metal complexes, and there are cases where the performance of single-molecule magnets is not ideal. Summary of the invention

[0004] In order to overcome the above defects and shortcomings in the prior art, the present invention provides a method for preparing a dysprosium-based single-molecule magnet with redox activity and its application.

[0005] The first object of the present invention is to provide a dysprosium-based single-molecule magnet having redox activity.

[0006] The second object of the present invention is to provide a method for preparing a dysprosium-based single-molecule magnet.

[0007] The third object of the present invention is to provide a dysprosium-based single-molecule magnet prepared by the above-mentioned preparation method.

[0008] The fourth object of the present invention is to provide the use of the above-mentioned dysprosium-based single-molecule magnet in the preparation of molecule-based magnetic materials.

[0009] Therefore, the present invention claims the following:

[0010] A dysprosium-based single-molecule magnet having redox activity, wherein the structural formula of the dysprosium-based single-molecule magnet is [(bbpen-Cl)Dy(μ-CA)Dy(bbpen-Cl)]·MeCN, wherein (bbpen-Cl) 2- N, N'-bis-(2-hydroxy-5-chloro-benzyl)-N, N'-bis-(2-pyridylmethyl)ethylenediamine anion, CA 2- It is the anion of chloranilic acid.

[0011] Preferably, the dysprosium-based single-molecule magnet is crystallized in the triclinic system, belongs to the P21 / c space group, and has a unit cell parameter of: α=90°, β=100.085(2)°, γ=90°,

[0012] A method for preparing a dysprosium-based single-molecule magnet comprises the following steps:

[0013] S1. The acetonitrile solution of chloranilic acid and triethylamine are fully reacted for 30 to 35 minutes to obtain a mixed solution;

[0014] S2. III The acetonitrile solution of (bbpen-Cl)NO3] is reacted with the mixed solution in step S1 at a temperature of 65-75°C for 30-35 minutes, and then the solid-liquid separation is performed to obtain the liquid, and the liquid is placed at 24-26°C for crystallization to obtain the dysprosium-based single-molecule magnet.

[0015] Said III[LnL(NO3)] is one of the “[LnL(NO3)]” in the prior art “Homotrinuclear lanthanide(III)arrays:assembly of and conversion from mononuclear and dinuclear units” (DOI: 10.1021 / ic991170j, publication date: March 7, 2001). The preparation method thereof can be found in “Syntheses of the Metal Complexes” and “[Ln(L1)(NO3)]·mH2O(Ln=Dy)” in the prior art, wherein H2L1(N,N'-bis(2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)-ethylenediamine, H2bbpen) is replaced by H2L2(N,N'-bis(5-chloro-2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)ethylenediamine, H2(Cl)bbpen) to prepare [Dy III (bbpen-Cl)NO3];

[0016] Said III The specific preparation method of [(bbpen-Cl)NO3] is as follows: 0.2mmol H2(Cl)bbpen and 0.4mmol NaOH methanol solution are added to 0.2mmol Dy(NO3)3·5H2O methanol solution, and then the mixture is stirred at room temperature for 1h. The resulting precipitate is collected by vacuum filtration and dried in air to obtain.

[0017] Preferably, in step S1, the usage ratio of chloranilic acid, acetonitrile and triethylamine is (0.008-0.012) mmol: (1.6-2.4) mL: (0.016-0.024) mmol.

[0018] More preferably, the usage ratio of chloranilic acid, acetonitrile and triethylamine is 0.01 mmol:2 mL:0.02 mmol.

[0019] Preferably, in step S2, the [Dy III The usage ratio of (bbpen-Cl)NO3] and acetonitrile is 0.01mmol:(4~6)mL.

[0020] More preferably, in step S2, the [Dy III The usage ratio of (bbpen-Cl)NO3] and acetonitrile is 0.01mmol:5mL.

[0021] More preferably, in the whole preparation process, the [Dy III The usage ratio of (bbpen-Cl)NO3] and acetonitrile was 0.01mmol:12mL.

[0022] Preferably, in step S1 and step S2, the reaction time is 30 min.

[0023] Preferably, in step S2, the reaction temperature is 70°C.

[0024] Preferably, in step S2, the method for crystallization is a slow volatilization method, specifically, the liquid is allowed to stand at 24-26° C. to evaporate slowly, and crystals are precipitated after one to two weeks.

[0025] A dysprosium-based single-molecule magnet prepared by any of the above preparation methods.

[0026] Application of any of the above-mentioned dysprosium-based single-molecule magnets in the preparation of molecule-based magnetic materials.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention discloses a preparation method and application of a dysprosium-based single-molecule magnet with redox activity. The structural formula of the dysprosium-based single-molecule magnet is [(bbpen-Cl)Dy(μ-CA)Dy(bbpen-Cl)]·MeCN. The present invention selects a high-performance dysprosium-based single-ion magnet primitive and a chloranilic acid bridging ligand to construct a zero-dimensional binuclear dysprosium-based single-molecule magnet with redox activity. The classic pentagonal bipyramidal configuration single-ion magnet primitive [Dy III (bbpen-Cl)] + The presence of enables the complex to maintain the significant magnetic anisotropy of the dysprosium ion, and the selected chloranilic acid bridging ligand can form a delocalized π radical regardless of oxidation or reduction, so the obtained product has both magnetic properties and redox activity. The construction and preparation of the redox-active dysprosium-based single-molecule magnet of the present invention also provides a new synthetic idea and method for obtaining such complexes.

[0029] The dysprosium-based single-molecule magnet of the present invention has the following advantages:

[0030] (1) The dysprosium-based single-molecule magnet with redox activity of the present invention has a zero-dimensional binuclear structure and good stability. It can be recrystallized in acetonitrile in the form of a complex to precipitate high-quality single crystals. The complex can form a delocalized π radical regardless of oxidation or reduction, and has redox activity.

[0031] (2) The preparation method of the dysprosium-based single-molecule magnet with redox activity of the present invention is simple and low-cost. The magnetic material with high yield and high crystallinity can be prepared by low-temperature heating reaction followed by volatilization at room temperature, which meets the requirements of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the synthesis of the dysprosium-based single-molecule magnet of Example 1.

[0033] Figure 2 The single crystal structure diagram of the dysprosium-based single-molecule magnet of Example 1; (a): the smallest asymmetric unit, (b): the zero-dimensional two-nuclear structure diagram, (c): the stacking diagram of the complex, (d): the central dysprosium ion is in a trigonal dodecahedral coordination configuration. All the structural diagrams omit H atoms for simplicity and clarity.

[0034] Figure 3 This is the infrared spectrum of the dysprosium-based single-molecule magnet of Example 1.

[0035] Figure 4 This is the electrospray ion mass spectrum of the dysprosium-based single-molecule magnet of Example 1.

[0036] Figure 5 This is the cyclic voltammetry curve of the dysprosium-based single-molecule magnet of Example 1.

[0037] Figure 6 This is a temperature-dependent magnetic susceptibility curve of the dysprosium-based single-molecule magnet of Example 1 under an external magnetic field of 1 kOe.

[0038] Figure 7 The temperature-dependent magnetization curve (a) and the reduced temperature-dependent magnetization intensity curve (b) of the dysprosium-based single-molecule magnet of Example 1 are shown.

[0039] Figure 8 The temperature-dependent AC magnetic susceptibility diagrams of the dysprosium-based single-molecule magnet of Example 1 at zero external field (a) and 2000 Oe (b), wherein the solid lines serve as indicators.

[0040] Fig. 9 1 is the Cole-Cole plot of the AC magnetic susceptibility of the dysprosium-based single-molecule magnet of Example 1 under zero external field (a) and 2000 Oe (b), and the solid line is the generalized Debye fitting result.

[0041] Fig.10 The temperature-dependent relaxation time distribution diagram of the dysprosium-based single-molecule magnet under zero field and optimal field of Example 1. The green solid line corresponds to the result of Arrhenius formula fitting in the high temperature region, and the blue and red solid lines correspond to the fitting results of the entire temperature range of zero field and optimal field, respectively.

[0042] Fig.11This is the X-ray powder diffraction pattern of the dysprosium-based single-molecule magnet of Example 1. DETAILED DESCRIPTION

[0043] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0044] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0045] Example 1 Synthesis of redox-active dysprosium-based single-molecule magnets

[0046] Schematic diagram of the synthesis of redox-active dysprosium-based single-molecule magnets Figure 1 shown.

[0047] 1. Weigh 2.1 mg (0.01 mmol) of chloranilic acid H2CA, add it to 2 mL of acetonitrile and stir, then add 0.02 mmol of triethylamine, remove the proton and continue stirring for 30 min until the solution completely turns blue-green;

[0048] 2. Weigh 14.2 mg of precursor [Dy III (bbpen-Cl)NO3] (0.02 mmol) was dissolved in 10 mL of acetonitrile by heating at 70°C, and then mixed with the blue-green solution in step 1 and continued to heat and stir for 30 min. A light orange-yellow solution was filtered and allowed to stand at room temperature for about 2 to 3 weeks to obtain yellow-brown block crystals, which were the dysprosium-based single-molecule magnet [(bbpen-Cl)Dy(μ-CA)Dy(bbpen-Cl)]·MeCN.

[0049] The precursors used [Dy III[LnL(NO3)] is one of the “[LnL(NO3)]” in the prior art “Homotrinuclear lanthanide(III)arrays:assembly of and conversion from mononuclear and dinuclear units” (DOI: 10.1021 / ic991170j, publication date: March 7, 2001). The preparation method thereof can be found in “Syntheses of the Metal Complexes” and “[Ln(L1)(NO3)]·mH2O(Ln=Dy)” in the prior art, wherein H2L1(N,N'-bis(2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)-ethylenediamine, H2bbpen) is replaced by H2L2(N,N'-bis(5-chloro-2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)ethylenediamine, H2(Cl)bbpen) to prepare [Dy III (bbpen-Cl)NO3];

[0050] [Dy III The specific preparation method of [Dy(bbpen-Cl)NO3] is as follows: 0.2mmol H2(Cl)bbpen and 0.4mmol NaOH in methanol solution are added to 0.2mmol Dy(NO3)3·5H2O in methanol solution, and then the mixture is stirred at room temperature for 1h. The resulting precipitate is collected by vacuum filtration and dried in air. After characterization and identification by elemental analyzer, mass spectrometry, infrared spectroscopy, thermogravimetric analysis and X-ray diffraction, it is proved that the synthesized substance is [Dy III (bbpen-Cl)NO3].

[0051] Example 2 Crystal structure determination and characterization

[0052] 1. Experimental Methods

[0053] The selected size is 0.042×0.034×0.031mm 3 The colorless bulk single crystal product was subjected to structural testing, and the Mo Kα rays were diffracted by a Bruker APEX-IICCD single crystal X-ray diffractometer at 120K, and the Mo Kα rays were monochromatized by a graphite monochromator. The diffraction data were collected and processed using the incident light source. All calculations were performed using the SHELXS-2015 and SHELXL-2015 programs.

[0054] 2. Experimental Results

[0055] The single crystal structure analysis shows that the dysprosium-based single-molecule magnet prepared in Example 1 (referred to as complex 1 in Table 1) belongs to the triclinic system, the space group is P21 / c, and the unit cell parameters are: α=90°, β=100.085(2)°, γ=90°, The crystallographic data are shown in Table 1.

[0056] Table 1 Crystallographic data and refinement results of dysprosium-based single-molecule magnets

[0057]

[0058]

[0059] Depend on Figure 2 As shown in (a) to (b), the asymmetric unit of the dysprosium-based single-molecule magnet prepared in Example 1 includes a Dy III , a bbpen-Cl 2- Chelating ligand and half of the deprotonated chloranilic acid CA 2- As a bridging ligand. Central metal ion Dy III It forms eight coordination with 4 N and 4 O, and the six coordination sites composed of 4 N and 2 O come from the same chelate ligand (bbpen-Cl) 2- (Specifically, four coordination sites come from the N atoms of the amine / pyridine groups on the ligands, and the other two coordination sites come from the O atoms of the phenol group), and the other two coordinated O atoms are provided by the bridging ligand CA 2- The other two para-O atoms of chloranilic acid are provided with another part [Dy(bbpen-Cl)] + The two basic units [Dy(bbpen-Cl)] + The shortest distance between The local coordination environment of the central Dy(III) is close to a trigonal dodecahedral coordination geometry (D 2d ), based on the ideal D 2d The CShM value calculated by Shape software is 2.225 (Table 2). The average Dy-O and Dy-N bond lengths are and The shortest Dy-O bond length is From the ligand bbpen-Cl 2- of phenolic oxygen.

[0060] Table 2 CShM values ​​of Dy(III) ions at the center of dysprosium-based single-molecule magnets

[0061]

[0062] From the infrared spectrum ( Figure 3 ) can be seen that at 1620cm -1 Obvious carbonyl peaks can be observed at 900-650cm -1 The out-of-plane deformation vibration of CH on the aromatic ring appeared in the region. Compared with the chloranilic acid ligand, the absorption peaks of some functional groups of the complex were red-shifted and the intensity also changed significantly, indicating that the redox-active organic bridging ligand chloranilic acid participated in the coordination.

[0063] Comparative Example 1

[0064] 1. Experimental Methods

[0065] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 2, no heating reaction was performed.

[0066] 2. Experimental Results

[0067] The reactants were insoluble, the final product was a powdery solid, and the complex crystals did not crystallize out.

[0068] Comparative Example 2

[0069] 1. Experimental Methods

[0070] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 2, the heating temperature was adjusted to be higher than 110°C.

[0071] 2. Experimental Results

[0072] Precursor [Dy III (bbpen-Cl)NO3] decomposes to produce a brown precipitate, and the target product cannot be obtained.

[0073] Comparative Example 3

[0074] 1. Experimental Methods

[0075] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 1, the stirring time was set to be less than 30 min.

[0076] 2. Experimental Results

[0077] The reactants cannot be completely dissolved and participate in the reaction. The product is a powdery solid precipitate or very small crystals, and the structure cannot be determined.

[0078] Comparative Example 4

[0079] 1. Experimental Methods

[0080] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 1, triethylamine was not added to remove the proton of chloranilic acid.

[0081] 2. Experimental Results

[0082] The product is a powdery solid, and the complex crystals are not precipitated.

[0083] Comparative Example 5

[0084] 1. Experimental Methods

[0085] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 1 and step 2, acetonitrile was replaced by ethanol.

[0086] 2. Experimental Results

[0087] The product is a powdery solid precipitate or microcrystals and cannot be structurally determined.

[0088] Comparative Example 6

[0089] 1. Experimental Methods

[0090] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 1 and step 2, acetonitrile was replaced by methanol.

[0091] 2. Experimental Results

[0092] The product was a powdery solid precipitate, and its structure could not be determined.

[0093] Comparative Example 7

[0094] 1. Experimental Methods

[0095] The dysprosium-based single-molecule magnet was synthesized by referring to the method of Example 1, except that in step 2, the precursor [Dy III (bbpen-Cl)NO3] was replaced by the precursor [Dy III (bbpen-Cl)Cl].

[0096] The precursors used [Dy IIIThe preparation method of [Dy(bbpen-Cl)Cl] is synthesized by referring to the preparation method of [Dy(bbpen)Cl] in the prior art "AStable Pentagonal Bipyramidal Dy(III) Single-Ion Magnet with a Record Magnetization Reversal Barrier over 1000K" (DOI: 10.1021 / jacs.6b02638, published on April 19, 2016), wherein H2bbpen is replaced with H2L2 (N,N'-bis(5-chloro-2-hydroxybenzyl)-N,N'-bis(2-pyridylmethyl)ethylenediamine, H2(Cl)bbpen) in the prior art "Homotrinuclearlanthanide(III)arrays:assembly of and conversion from mononuclear and dinuclear units" (DOI: 10.1021 / ic991170j, published on March 7, 2001), to obtain [Dy(bbpen-Cl)Cl] III (bbpen-Cl)Cl];

[0097] The specific preparation method is: add 0.2 mmol triethylamine dropwise into a solution (5 mL) of 0.1 mmol DyCl3·6H2O and 0.1 mmol H2(Cl)bbpen in ethanol. After stirring for 5 minutes, filter the resulting mixture immediately, and slowly evaporate the filtrate at room temperature to obtain the product. Characterization and identification by elemental analyzer, mass spectrometry, infrared spectrum, thermogravimetric analysis and X-ray diffraction prove that the synthesized substance is [Dy III (bbpen-Cl)Cl].

[0098] 2. Experimental Results

[0099] Although the target crystalline product was obtained, the yield was reduced and there were white hard filamentous impurities.

[0100] It can be seen from the comparison between Example 1 and Comparative Examples 1 to 7 that the preparation of the dysprosium-based single-molecule magnet of the present invention requires [Dy III (bbpen-Cl)NO3] is used as a precursor, acetonitrile is used as a solvent, and triethylamine is added to remove the proton of chloranilic acid at a reaction temperature of 70°C for sufficient reaction, thereby forming an external environment that is conducive to the reaction between the high-performance single-ion magnet unit and the chloranilic acid bridging ligand, and is also conducive to the crystallization of the final complex product with a suitable solubility, thereby obtaining a high-quality, high-purity redox-active dysprosium-based single-molecule magnet.

[0101] Example 3 Electrospray ionization mass spectrometry

[0102] 1. Experimental Methods

[0103] The dysprosium-based single-molecule magnet prepared in Example 1 was analyzed by electrospray ionization mass spectrometry (ESI-MS).

[0104] 2. Experimental Results

[0105] The dysprosium-based single-molecule magnet prepared in Example 1 can be recrystallized in acetonitrile to obtain high-quality crystals, and the crystals can be analyzed by ESI-MS ( Figure 4 )、X-ray powder diffraction( Fig.11 ) and elemental analysis results confirmed that [(bbpen-Cl)Dy(μ-CA)Dy(bbpen-Cl)]·MeCN can be stably present in the form of a complex in acetonitrile. ESI-MS ( Figure 4 ) has a peak at m / z=1574, corresponding to the molecular ion of the complex anion, which is consistent with the theoretical isotope distribution diagram simulated and calculated by the software Isotope Viewer.

[0106] Example 4 Cyclic voltammetry curve

[0107] 1. Experimental Methods

[0108] In a 0.1M Bu4NPF6 (tetra-n-butylammonium hexafluorophosphate) supported electrolyte in MeCN, a three-electrode system was used: silver / silver chloride was used as a reference electrode, a platinum sheet electrode was used as a working electrode, and a platinum electrode was used as a counter electrode. The electrochemical window was (-2.5V, 2.5V), and the cyclic voltammetry curve of the dysprosium-based single-molecule magnet prepared in Example 1 was measured at 295K at a scanning speed of 0.1V / s.

[0109] 2. Experimental Results

[0110] The results are as follows Figure 5 As shown, the two pairs of reversible redox potential peaks are -1.598V, -0.913V; -1.410V, -0.843V, respectively, which once again proves that the dysprosium-based single-molecule magnet prepared in Example 1 has redox activity and is in an intermediate valence state, and can reach other states regardless of the oxidation process or the reduction process.

[0111] Example 5 Variable Temperature DC Magnetic Susceptibility Test

[0112] 1. Experimental Methods

[0113] Under an external DC magnetic field of 1000 Oe, a variable temperature DC magnetic susceptibility test was performed on the polycrystalline powder sample of the dysprosium-based single-molecule magnet prepared in Example 1 within a temperature range of 2 to 300 K.

[0114] 2. Experimental Results

[0115] The results are as follows Figure 6 As shown, at room temperature 300K, the molar magnetic susceptibility χ of the dysprosium-based single-molecule magnet prepared in Example 1 is M T The test value is 27.63cm 3 K mol -1 , which is lower than the theoretical value. This may be due to the large anisotropy in the system. 6 H 15 / 2 The crystal field splitting of the ground state. As the temperature decreases, M T The value shows a decreasing trend, but the amplitude is not large.

[0116] Example 6 Magnetization intensity test

[0117] 1. Experimental Methods

[0118] The magnetization intensity of the powder sample of the dysprosium-based single-molecule magnet prepared in Example 1 was tested at temperatures of 5K, 10K, and 15K and a magnetic field range of 0 to 7T.

[0119] 2. Experimental Results

[0120] like Figure 7 As shown in (a), with the increase of the external magnetic field, the magnetization intensity of the dysprosium-based single-molecule magnet of the present invention increases significantly; when it increases to a certain extent, the growth rate slows down and gradually tends to saturation. When the temperature is 5K and the external magnetic field is 7T, the maximum value is 10.057Nμ B , indicating that there is obvious zero-field splitting in the dysprosium-based single-molecule magnet of the present invention, and it has significant magnetic anisotropy.

[0121] like Figure 7 As shown in (b), the reduced temperature-dependent magnetization intensity curves (MH / T) of the dysprosium-based single-molecule magnet of the present invention basically coincide with each other, indicating that there is large anisotropy and obvious zero-field splitting in the complex, which is consistent with the results of the temperature-dependent DC magnetic susceptibility curve analyzed in Example 5, indicating that the dysprosium-based single-molecule magnet of the present invention has an approximate Ising ground state and exhibits the properties of a single-molecule magnet.

[0122] Example 6 Slow magnetic relaxation behavior

[0123] 1. Experimental Methods

[0124] In order to further analyze the slow magnetic relaxation behavior of the dysprosium-based single-molecule magnet prepared in Example 1, characterization tests of variable temperature and variable frequency AC magnetic susceptibility were carried out under external magnetic fields of 0 Oe and 2000 Oe.

[0125] 2. Experimental Results

[0126] like Figure 8 As shown in (a) to (b), under zero external field, both the real and imaginary parts of the AC magnetic susceptibility of the dysprosium-based single-molecule magnet prepared in Example 1 show obvious frequency-dependent behavior, and when the frequency is higher than 388 Hz, a peak value of the imaginary part of the AC magnetic susceptibility can be observed, and its peak temperature is about 42 K. When the temperature is lower than 11 K, the real part χ′ M T At low temperatures, it no longer changes with frequency, while the imaginary susceptibility rises as the temperature decreases, showing a so-called "tail", which means the emergence of quantum tunneling relaxation. At the same time, we noticed that even at the highest frequency of 999Hz, the "tail" phenomenon still exists, but the high frequency will weaken it. With the introduction of a 2000Oe DC field, the tunneling process at low temperatures is obviously suppressed and disappears. We can intuitively see that even at the lowest frequency of 0.1Hz, the AC susceptibility has a peak at 8K, the "tail" phenomenon completely disappears and the peak shape becomes sharper. At the same time, the frequency of the AC magnetic field resonates with the quantum decoherence, and the imaginary part of the AC susceptibility at the highest frequency of 999Hz peaks at a high temperature of 44K.

[0127] The Cole-Cole plots of the relaxation time and relaxation time distribution factor α were obtained by using the variable frequency AC magnetic susceptibility data of the dysprosium-based single-molecule magnet according to the generalized Debye model. The values ​​are between 0.012 and 0.241 and 0.011 and 0.094 under zero field and 2000Oe optimal field, respectively. Fig. 9 ).

[0128] The natural logarithm of the magnetic relaxation time ln(τ) of the Dysprosium-based single-molecule magnet varies with the inverse of the temperature T -1 The changing trend is Fig.10 In the high temperature region, the logarithm of the relaxation time ln(τ) changes linearly with the inverse of the temperature, indicating that the high temperature section undergoes an Orbach process, and the spin flip energy barrier U can be fitted. eff / k B =333(12)K and pre-exponential factor τ0 = 1.0(3)×10 -7 s, when the field is 2000Oe, τ0=8(2)×10 -8 As the temperature decreases, the natural logarithm of the relaxation time ln(τ) of the complex under zero external field changes with the inverse of the temperature T -1The change gradually deviates from linearity and no longer conforms to the Arrhenius formula. It gradually becomes flat after 11K, indicating that the quantum tunneling process begins to dominate after this temperature. After the external field is applied, the relaxation time continues to increase, indicating the existence of the Raman process. Multiple relaxation is used to fit the relaxation process of the complex in the entire temperature range and the following parameters are obtained: Under zero field, τ 0(0Oe) =8(1)×10 -10 s, C (0Oe) =0.0143s -1 K -n , n = 3.19 (23), τ QTM(0Oe) =0.00437s; when the field is 2000Oe: τ 0(2000Oe) =8.0(5)×10 -10 s, C (2000Oe) =1.4(2)×10 -4 s -1 K -n , n = 4.33 (5), and share the energy barrier U eff / k B =573(10)K.

[0129] Example 7 X-ray powder diffraction pattern

[0130] 1. Experimental Methods

[0131] The dysprosium-based single-molecule magnet prepared in Example 1 was placed in air for two weeks and then subjected to X-ray powder diffraction testing.

[0132] 2. Experimental Results

[0133] Depend on Fig.11 It can be seen that the peak position, peak shape and peak intensity of the simulation peak and the test peak are basically consistent, indicating that the dysprosium-based single-molecule magnet of the present invention is relatively stable and can be stored in an air environment for a long time.

[0134] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A dysprosium-based single-molecule magnet having redox activity, characterized in that: The structural formula of the dysprosium-based single-molecule magnet is [(bbpen-Cl)Dy(μ-CA)Dy(bbpen-Cl)]·MeCN, where (bbpen-Cl) 2- N, N'-bis-(2-hydroxy-5-chloro-benzyl)-N, N'-bis-(2-pyridylmethyl)ethylenediamine anion, CA 2- It is the anion of chloranilic acid; The dysprosium-based single-molecule magnet is crystallized in the triclinic system, belongs to the P21 / c space group, and has the unit cell parameters: α=90°, β=100.085(2)°, γ=90°, 2. The method for preparing the dysprosium-based single-molecule magnet according to claim 1, characterized in that: The following steps are involved: S1. The acetonitrile solution of chloranilic acid and triethylamine are fully reacted for 30 to 35 minutes to obtain a mixed solution; S2. III The acetonitrile solution of (bbpen-Cl)NO3] is reacted with the mixed solution in step S1 at a temperature of 65-75°C for 30-35 minutes, and then the solid-liquid separation is performed to obtain the liquid, and the liquid is placed at 24-26°C for crystallization to obtain the dysprosium-based single-molecule magnet.

3. The preparation method according to claim 2, characterized in that: In step S1, the usage ratio of chloranilic acid, acetonitrile and triethylamine is (0.008-0.012) mmol: (1.6-2.4) mL: (0.016-0.024) mmol.

4. The preparation method according to claim 3, characterized in that: The usage ratio of chloranilic acid, acetonitrile and triethylamine is 0.01mmol:2mL:0.02mmol.

5. The preparation method according to claim 2, characterized in that: In step S2, the [Dy III The usage ratio of (bbpen-Cl)NO3] and acetonitrile is 0.01mmol:(4~6)mL.

6. The preparation method according to claim 2, characterized in that: In step S1 and step S2, the reaction time is 30 min.

7. The preparation method according to claim 2, characterized in that: In step S2, the reaction temperature is 70°C.

8. Use of the dysprosium-based single-molecule magnet according to claim 1 in the preparation of molecule-based magnetic materials.

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