Novel 1, 3, 5-tri (carboxyl methoxy) benzene dysprosium metal complex with three-dimensional structure and synthesis method of 1, 3, 5-tri (carboxyl methoxy) benzene dysprosium metal complex

Abstract

The invention relates to a dysprosium complex [Dy (H3L) Cl3]. H2O, in which H3L is equal to 1, 3, 5-tri (carboxyl methoxy) benzene. An asymmetric structural unit of the dysprosium complex is formed by coordination of a Dy < 3 + > and a carboxylic acid ligand which is not deprotonated, the dysprosium complex further comprises a free water molecule and three free chloride ions, and the occupancy rate of two chlorine ions is 0.5; the central metal ion Dy < 3 + > in the molecule and nine carboxylic acid oxygen atoms on six ligands form a single-cap tetragonal reverse prism structure through nine coordination; every two adjacent Dy < 3 + > in the dysprosium complex are connected and further expanded through oxygen atoms in ligand carboxylic acid and are orderly stacked into a three-dimensional structure through the pi-pi action of ligand benzene rings.

Description

Technical Field

[0001] This invention relates to the field of chemistry, specifically to a dysprosium complex [Dy(H3L)Cl3]·H2O and its preparation method. Background Technology

[0002] Photocatalysis technology can convert solar energy into chemical energy, with applications in various fields such as water splitting, carbon dioxide reduction, organic small molecule conversion, and pollutant degradation. However, the efficiency of existing inorganic semiconductor photocatalysts is insufficient for industrial applications, and adding co-catalysts introduces new problems. Therefore, the development of novel photocatalysts that do not require co-catalysts has become an urgent need in the industry. Metal-organic frameworks (MOFs) are porous crystalline materials composed of interconnected metal ions / clusters and multidentate organic ligands. They can absorb light and generate charge-separated states by directly exciting metal clusters or organic ligands. This characteristic is similar to that of semiconductor photocatalysts, making them suitable for photocatalytic reactions. Moreover, MOF catalysis has advantages over traditional catalysis, such as high porosity, adjustable light absorption range, shortened charge transfer paths, and improved electron-hole separation. Currently, the photocatalytic performance of MOFs is mainly applied in photocatalytic hydrogen production, photocatalytic CO2 reduction, and photocatalytic degradation of dyes and heavy metal ions. In addition, crystalline MOFs have well-defined composition and structure, which are easy to adjust. Therefore, MOF materials are also an ideal model for exploring the composition-structure-performance relationship in photocatalytic systems, and can provide guidance for the rational design and development of photocatalytic materials at the molecular level.

[0003] Organic ligands and metal active centers influence the structure and properties of MOF materials. Organic ligands contain various coordinating groups, among which carboxyl ligands, possessing multiple coordination nodes, are often selected as multifunctional organic ligands. These nodes promote diverse coordination modes between ligands and metal ions, facilitating the construction of rich structural topologies in MOFs. Rare earth metal ions can endow materials with higher coordination numbers and richer coordination geometries. High coordination numbers result in structural stability and unique optical, magnetic, and electrical properties, providing broad prospects for their application in photocatalysis and electrocatalysis. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a dysprosium complex [Dy(H3L)Cl3]·H2O and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A dysprosium complex, the chemical formula of which is [Dy(H3L)Cl3]·H2O, wherein H3L = 1,3,5-tris(carboxymethoxy)benzene, the crystallographic parameters of which are shown in Table 1, and some bond lengths and bond angles of which are shown in Table 2.

[0006] The dysprosium complex, wherein the asymmetric structural unit of the dysprosium complex is composed of a Dy 3+ It coordinates with an undeprotonated carboxylic acid ligand to form a molecule containing one free water molecule and three free chloride ions, with the two chloride ions comprising 0.5% of the molecule; the central metal ion Dy in the molecule 3+ The dysprosium complex forms a monocapped tetragonal antiprism configuration through nine coordinations with the nine carboxylic acid oxygen atoms on the six ligands; each pair of adjacent Dy atoms in the dysprosium complex... 3+ All of these structures are further extended through the connection of oxygen atoms in the ligand carboxylic acid and are orderly stacked into three-dimensional structures through the π··π interaction of the ligand benzene ring. The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O includes the following steps: (1) The reaction system includes: a) A 55-65% (v / v) aqueous solution of acetonitrile; b) Dysprosium chloride hexahydrate, the amount of which is 0.048~0.052 mmol per 5 mL of the acetonitrile aqueous solution; c) 1,3,5-tris(carboxymethoxy)benzene, wherein the molar ratio of its amount to the dysprosium chloride hexahydrate is 1:0.9~1.1.

[0007] (2) The reaction system is stirred evenly in a container, and then concentrated nitric acid is added dropwise to the container. The amount of concentrated nitric acid used is 0.04~0.06 mL of concentrated nitric acid per 5 mL of the acetonitrile aqueous solution. The mixture is stirred evenly. (3) Transfer the reaction system to a reaction vessel and react in an oven at 125-135 °C. After the reaction is completed, remove the system, cool it, filter it, and wash it to obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

[0008] The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O includes the following steps: (1) Weigh 0.05 mmol of 1,3,5-tris(carboxymethoxy)benzene and 0.05 mmol of dysprosium chloride hexahydrate and put them into a 25 mL beaker; (2) Measure 3 mL of acetonitrile and 2 mL of distilled water with a graduated cylinder, pour them into a 25 mL beaker, stir with a glass rod, then add a stir bar and stir with a magnetic stirrer at room temperature for about half an hour. (3) Add one drop of concentrated nitric acid to a 25 mL beaker, then place it in an ultrasonic instrument and vibrate for ten minutes. (4) Remove the stir bar, pour the reaction system into the reactor liner, cover it and put in the iron sleeve, react in an oven at 130°C for 72 h, remove it and cool it to room temperature, filter it, wash it, and obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

[0009] Compared with the prior art, the present invention has the following beneficial effects: A novel dysprosium complex [Dy(H3L)Cl3]·H2O, a rare-earth material for 3D-MOFs, was constructed using 1,3,5-tris(carboxymethoxy)benzene as a directional ligand. The composition and structure of the rare-earth MOFs were characterized by infrared spectroscopy, elemental analysis, and X-ray single-crystal diffraction. The photocatalytic performance of the material was investigated using UV-Vis DRS, Mott-Schottky spectroscopy, photocurrent response, and electrochemical impedance spectroscopy (EIS). Attached Figure Description

[0010] Figure 1 This is the synthesis scheme for the dysprosium complex.

[0011] Figure 2 This is a crystal structure diagram of the dysprosium complex.

[0012] Figure 3 The diagram shows the coordination polyhedron of the central ion in the dysprosium complex.

[0013] Figure 4 This is a three-dimensional packing diagram of the dysprosium complex.

[0014] Figure 5 The image shows the infrared spectrum of the 1,3,5-tris(carboxymethoxy)benzene ligand and the dysprosium complex.

[0015] Figure 6 This is a surface force diagram of the dysprosium complex.

[0016] Figure 7 This is a two-dimensional fingerprint region diagram of the surface interaction of the dysprosium complex.

[0017] Figure 8 The image shows the UV-Vis spectrum of the dysprosium complex. The horizontal axis represents wavelength, and the vertical axis represents absorbance.

[0018] Figure 9 This is a band gap diagram of the dysprosium complex. The horizontal axis represents photon energy, the vertical axis α represents the absorption coefficient of the material, hν is the photon energy, n is the exponent, and n=2 represents the direct band gap.

[0019] Figure 10 This is a Mott-Schottky curve of the dysprosium complex. The horizontal axis represents the potential (relative to SCE), and the vertical axis represents C. - ² represents the reciprocal square of the space charge layer capacitance, with units of F. - 2 cm 4 .

[0020] Figure 11 The graph shows the instantaneous photocurrent response of the dysprosium complex. The horizontal axis represents time, and the vertical axis represents current density.

[0021] Figure 12 This is the electrochemical impedance spectroscopy (EIS) spectrum of the dysprosium complex. The horizontal axis represents the real impedance in ohms. The value of the horizontal axis reflects the total resistance encountered by the charge during transport within the electrode material and at the interface. The radius of the arc directly corresponds to the charge transfer resistance; a smaller radius indicates higher charge separation and transport efficiency. The vertical axis represents the imaginary impedance in ohms. Detailed Implementation

[0022] The technical solution of the present invention will be further illustrated below through embodiments.

[0023] The experimental instruments used in the examples were: Bruker Smart CCD single-crystal diffractometer, Perkin-Elmer 240Q elemental analyzer, Spectrum 65 Fourier transform infrared spectrometer, Shimadzu UV-2700 UV-Vis spectrophotometer, Bruker Advance III 400MHz NMR spectrometer, JASCO FP-6500 solid-state fluorescence spectrophotometer, Agilent 7820A gas chromatograph, MC-XS500 xenon lamp light source system, and CHI 760E electrochemical workstation.

[0024] Experimental reagents used in the examples: All chemical reagents and chemicals used in the experiments were analytical grade reagents, including 1,3,5-tris(carboxymethoxy)benzene (Jinan Henghua Technology Co., Ltd.), dysprosium chloride hexahydrate (Shanghai Maclean Biochemical Technology Co., Ltd.), acetonitrile, nitric acid, anhydrous ethanol, DMF (Xilong Chemical Co., Ltd.), and ordinary reagent-grade concentrated nitric acid with a mass fraction of 65-68%.

[0025] Example 1 Synthesis of dysprosium complexes 1.1 Synthesis method of the dysprosium complex [Dy(H3L)Cl3]·H2O (1) Weigh 0.05 mmol (0.0151 g) of 1,3,5-tris(carboxymethoxy)benzene (H3L) and 0.05 mmol (0.0189 g) of dysprosium chloride hexahydrate and put them into a 25 mL beaker; (2) Measure 3 mL of acetonitrile and 2 mL of distilled water with a graduated cylinder, pour them into a 25 mL beaker, stir with a glass rod, then add a stir bar and stir with a magnetic stirrer at room temperature for about half an hour. (3) Add one drop of concentrated nitric acid to a 25 mL beaker, then place it in an ultrasonic instrument and vibrate for ten minutes. (4) Remove the stir bar, pour the reaction system into the reactor liner, cover it and put it in an iron sleeve, react in an oven at 130°C for 72 h, remove it and cool it to room temperature, filter it to obtain light yellow needle-like crystals, which are dysprosium complex [Dy(H3L)Cl3]·H2O.

[0026] Elemental analysis C 24 H 20 Cl3DyO 19 Theoretical values: C, 32.68; H, 2.27; Test values: C, 32.65; H, 2.29.

[0027] IR(KBr, cm -1 ): 1632, 1435, 1350, 1170, 1079, 738.

[0028] The synthesis scheme for the dysprosium complex is as follows: Figure 1 The dysprosium complex samples prepared in Example 1 were applied to the experiments in Examples 2-5.

[0029] Example 2 Crystal Structure Analysis 2.1 Crystal Structure Determination Methods A dysprosium complex [Dy(H3L)Cl3]·H2O sample measuring 0.15 mm × 0.11 mm × 0.10 mm was selected. It was placed on an X-ray single-crystal diffractometer using a graphite-monochromatic Mo-Kα diffraction source (λ = 0.71073 Å). At 100 K, the data collection angle range for the dysprosium complex [Dy(H3L)Cl3]·H2O was 3.326 ° < 2θ < 50.7 °. Structural analysis, refinement, and plotting were performed using Olex2 software.

[0030] 2.2 Results of Crystal Structure Determination The crystallographic parameters of dysprosium complexes are shown in Table 1, and Table 2 is a partial table of bond lengths and bond angles of dysprosium complexes.

[0031] 2.2.1 The structural analysis of dysprosium complexes is as follows: As shown in Table 1, the dysprosium complex [Dy(H3L)Cl3]·H2O belongs to the monoclinic crystal system, and its space group is [missing information]. C2 / c Its asymmetric structural unit consists of a Dy 3+ It coordinates with an undeprotonated carboxylic acid ligand to form a compound containing one free water molecule and three free chloride ions (two chloride ions occupying 0.5% of the compound).

[0032] from Figure 2 , Figure 3It can be seen that the central metal ion Dy in the dysprosium complex molecule 3+ It forms a single-cap tetragonal antiprism configuration by nine coordinations with the nine carboxylic acid oxygen atoms on the six ligands.

[0033] from Figure 4 It can be seen that in dysprosium complexes, every two adjacent Dy 3+ All of these structures are further extended through the connection of oxygen atoms in the ligand carboxylic acid and are orderly stacked into three-dimensional structures through the π··π interaction of the ligand benzene ring. Table 1. Crystallographic parameters of dysprosium complexes

[0034] Note: [a] R 1 = Σ|| F o | – | F c || / Σ| F o |. [b] wR 2 = [Σ w (| F o 2 |– | F c 2 |) 2 / Σ w (| F o 2 |) 2 ] 1 / 2 . Table 2. Partial bond lengths and bond angles of dysprosium complex [Dy(H3L)Cl3]·H2O

[0035] Example 3 Infrared Spectroscopy 3.1 Infrared Spectroscopy Test Method (1) Take an appropriate amount of potassium bromide and put it into an oven to dry. Then, under an infrared lamp, take an appropriate amount of potassium bromide and grind it in an agate mortar. Add the sample according to the ratio of sample / KBr = 1 / 100 (w / w) and mix and grind the two thoroughly.

[0036] (2) Take an appropriate amount of the mixture and press it into a mold to form a sample sheet with uniform thickness, no cracks, and light transmission. Use a Spectrum 65 Fourier transform infrared spectrometer to measure the sample with air as the background at 4000-400 cm⁻¹. -1The sample was scanned within a wavelength range to measure its infrared spectrum. In this embodiment, the sample was a 1,3,5-tris(carboxymethoxy)benzene ligand and dysprosium complex, and the test results are as follows: Figure 5 As shown.

[0037] 3.2 Results and Analysis of Infrared Spectroscopy Tests from Figure 5 As can be seen, the broad absorption peaks of the 1,3,5-tris(carboxymethoxy)benzene ligand and the dysprosium complex are located at 3408 cm⁻¹. -1 3425 cm -1 3430 cm -1 It is a characteristic absorption peak of the bending vibration of the OH bond in the -COOH group.

[0038] For the 1,3,5-tris(carboxymethoxy)benzene ligand, the C=O stretching vibration of the -COOH group is located at 1748 cm⁻¹. -1 The stretching vibration of the benzene ring C=C skeleton is located at 1603 cm⁻¹. -1 1472 cm -1 The stretching vibration of the CO bond is located at 1347 cm. -1 1170cm -1 1231 cm -1 The external bending vibration of the CH bond in the benzene ring is located at 676 cm⁻¹. -1 .

[0039] The stretching vibrations of the C=O bonds and the C=C skeleton of the benzene ring in the dysprosium complex were transferred to 1632 cm⁻¹. -1 1435 cm -1 , The CO bond stretching vibration of the dysprosium complex is located at 1350 cm⁻¹. -1 1170 cm -1 1079 cm -1 , The characteristic absorption peak of the Dy-O bond in the dysprosium complex appears at 738 cm⁻¹. -1 , This shows that in dysprosium complexes, rare earth metal ions are coordinated with oxygen in the ligands.

[0040] Example 4: Hirshfeld Surface Analysis Using the crystal parameter CIF file of the sample as the data source, the distribution of Hirshfeld surface forces of the sample molecules was calculated using CrystalExplorer 3.1. Different intermolecular interactions were visualized on the three-dimensional molecular surface of the crystal structure, yielding Denorm, Shape index, and Curvedness maps. Furthermore, 2D fingerprinting was used to quantitatively analyze the nature and molecular type of the surface forces between molecules within the sample crystal, resulting in the surface force map and 2D fingerprint of the sample, as shown below. Figure 6-12 As shown. The sample described in this embodiment is a dysprosium complex.

[0041] from Figure 6 As can be seen, the Dnorm surface has red spots, indicating that the dysprosium complex has relatively strong surface forces at these locations. The Shape index surface has bright yellow irregular patches, indicating that the dysprosium complex has intermolecular π··π interactions at these locations.

[0042] Depend on Figure 7 As can be seen, the largest proportion of dysprosium complexes is the H···H interaction, accounting for 18.0%. The O···H / H···O interaction accounts for 12.7% of the dysprosium complexes.

[0043] Example 5 Photoelectrochemical Performance 5.1 Photoelectrochemical Testing Methods A clean ITO glass (1 cm × 2 cm) was taped onto cardstock, leaving a 1 cm × 1 cm sample area. The synthesized sample (10 mg) was then dispersed in a centrifuge tube containing 1 mL of ethanol solution and sonicated until a uniformly dispersed suspension was formed. A pipette was used to transfer a drop of the suspension to the reserved sample area on the ITO glass, and the sample was allowed to air dry at room temperature. The ITO glass (1 cm × 2 cm) was used as the working electrode, Pt as the auxiliary electrode, Ag / AgCl as the reference electrode, and 0.1 mol / L sodium sulfate solution as the electrolyte.

[0044] The UV-Vis diffuse reflectance was corrected using barium sulfate white powder as a baseline. The Mott Schottky test frequencies were 500 Hz, 800 Hz, and 1000 Hz. The instantaneous photocurrent test was performed with the lamp turned on or off every ten seconds.

[0045] 5.2 Ultraviolet-Vis Diffuse Reflectance (UV-vis DRS) To understand the photoelectrochemical properties of dysprosium complexes and to further study their photocatalytic performance, their ultraviolet-visible diffuse reflectance (UV-vis DRS) spectra were measured. Their light absorption capacity was evaluated by calculating the band gap values. The results are as follows: Figure 8-9 As shown.

[0046] from Figure 8 As can be seen, dysprosium complexes have a wide and distinct visible light absorption range (around 200-560 nm).

[0047] from Figure 9 It can be seen that the band gap energy (Eg) of the dysprosium complex can be deduced to be 2.31 eV.

[0048] 5.3 Mott-Shotkey The Mott-Schottky curve is an important tool for studying the characteristics of semiconductor electrode / solution interfaces or metal / semiconductor Schottky junctions through electrochemical impedance spectroscopy. It is primarily used to determine the carrier concentration and flat-band potential of semiconductors. Results are as follows... Figure 10 As shown.

[0049] from Figure 10 As can be seen, the slopes of the fitted lines are all positive, indicating that the dysprosium complex is an n-type semiconductor. The estimated E0 of the dysprosium complex... fb The value is 0.19 eV vs Ag / AgCl (0.39 eV vs NHE), and the conduction band CB of the dysprosium complex is 0.39 eV relative to the standard hydrogen electrode potential. Therefore, using the band gap energy equation (E... VB =E CB +E g The valence band VB of the dysprosium complex was calculated to be 2.70 eV vs NHE.

[0050] 5.4 Instantaneous photocurrent test The height of the peaks in the photocurrent response graph represents the strength of the photocurrent response. Figure 11 It is a photocurrent response test spectrum obtained by periodically turning the lamp on or off on the dysprosium complex.

[0051] Depend on Figure 11 It can be seen that when the light is turned on, the dysprosium complex can generate a stable sloping peak, which indicates the generation of a photocurrent signal, reflecting the charge transfer between the complex and the electrode. The current response difference of the dysprosium complex between the on and off states is 0.35 μAcm. -2 .

[0052] 5.5 Electrochemical Impedance Figure 12 This is the electrochemical impedance spectroscopy of a dysprosium complex. The diameter of the semicircle in the high-frequency region of the graph reflects the magnitude of the charge transfer resistance (Rct).

[0053] Example 2 The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O includes the following steps: (1) The reaction system includes: a) A 65% (v / v) aqueous solution of acetonitrile; b) Dysprosium chloride hexahydrate, the amount of which is 0.052 mmol per 5 mL of the acetonitrile aqueous solution; c) 1,3,5-tris(carboxymethoxy)benzene, wherein the molar ratio of its amount to the dysprosium chloride hexahydrate is 1:1.1.

[0054] (2) The reaction system is stirred evenly in a container, and then concentrated nitric acid is added dropwise to the container. The amount of concentrated nitric acid used is 0.06 mL of concentrated nitric acid for every 5 mL of the acetonitrile aqueous solution. The mixture is stirred evenly. (3) The reaction system was transferred to a reaction vessel and reacted in an oven at 135 °C. After the reaction was completed, the system was taken out, cooled, filtered, and washed to obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

[0055] Example 3 The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O includes the following steps: (1) The reaction system includes: a) A 55% (v / v) aqueous solution of acetonitrile; b) Dysprosium chloride hexahydrate, the amount of which is 0.048 mmol per 5 mL of the acetonitrile aqueous solution; c) 1,3,5-tris(carboxymethoxy)benzene, wherein the molar ratio of its amount to that of the dysprosium chloride hexahydrate is 1:0.9.

[0056] (2) The reaction system is stirred evenly in a container, and then concentrated nitric acid is added dropwise to the container. The amount of concentrated nitric acid used is 0.04 mL of concentrated nitric acid for every 5 mL of the acetonitrile aqueous solution. The mixture is stirred evenly. (3) The reaction system was transferred to a reaction vessel and reacted in an oven at 125 °C. After the reaction was completed, the system was taken out, cooled, filtered, and washed to obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

[0057] Example 4 The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O includes the following steps: (1) The reaction system includes: a) 55%, 57%, 60%, 62.5%, or 65% (v / v) aqueous acetonitrile solution; b) Dysprosium chloride hexahydrate, in amounts of 0.048, 0.049, 0.050, 0.051, or 0.052 mmol per 5 mL of the acetonitrile aqueous solution; c) 1,3,5-tris(carboxymethoxy)benzene, wherein the molar ratio of its amount to the dysprosium chloride hexahydrate is 1:0.9, 1.0, or 1.1.

[0058] (2) The reaction system is stirred evenly in a container, and then concentrated nitric acid is added dropwise to the container. The amount of concentrated nitric acid used is 0.04, 0.05, or 0.06 mL of concentrated nitric acid per 5 mL of the acetonitrile aqueous solution. The mixture is stirred evenly. (3) Transfer the reaction system to a reaction vessel and react in an oven at 125, 128, 130, 132 or 135 °C. After the reaction is completed, remove the system, cool it, filter it and wash it to obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

Claims

1. A dysprosium complex, characterized in that, The chemical formula of the dysprosium complex is [Dy(H3L)Cl3]·H2O, where H3L = 1,3,5-tris(carboxymethoxy)benzene. The crystallographic parameters of the dysprosium complex are shown in Table 1, and some bond lengths and bond angles of the dysprosium complex are shown in Table 2. Table 1. Crystallographic parameters of dysprosium complexes Table 2. Partial bond lengths and bond angles of dysprosium complex [Dy(H3L)Cl3]·H2O 。 2. The dysprosium complex as described in claim 1, characterized in that, The asymmetric structural unit of the dysprosium complex is composed of a Dy 3+ It coordinates with an undeprotonated carboxylic acid ligand to form a molecule containing one free water molecule and three free chloride ions, with the two chloride ions comprising 0.5% of the molecule; the central metal ion Dy in the molecule 3+ The dysprosium complex forms a monocapped tetragonal antiprism configuration through nine coordinations with the nine carboxylic acid oxygen atoms on the six ligands; each pair of adjacent Dy atoms in the dysprosium complex... 3+ All of these structures are further extended through the connection of oxygen atoms in the ligand carboxylic acid and are orderly stacked into three-dimensional structures through the π··π interaction of the ligand benzene ring.

3. The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O as described in claim 1, characterized in that, Includes the following steps: (1) The reaction system includes: a) A 55-65% (v / v) aqueous solution of acetonitrile; b) Dysprosium chloride hexahydrate, the amount of which is 0.048~0.052 mmol per 5 mL of the acetonitrile aqueous solution; c) 1,3,5-tris(carboxymethoxy)benzene, wherein the molar ratio of its amount to the dysprosium chloride hexahydrate is 1:0.9~1.

1.

4. (2) The reaction system is stirred evenly in a container, and then concentrated nitric acid is added dropwise to the container. The amount of concentrated nitric acid used is 0.04~0.06 mL of concentrated nitric acid per 5 mL of the acetonitrile aqueous solution. The mixture is stirred evenly. (3) Transfer the reaction system to a reaction vessel and react in an oven at 125-135 °C. After the reaction is completed, remove the system, cool it, filter it, and wash it to obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

5. The method for synthesizing the dysprosium complex [Dy(H3L)Cl3]·H2O as described in claim 3, characterized in that, Includes the following steps: (1) Weigh 0.05 mmol of 1,3,5-tris(carboxymethoxy)benzene and 0.05 mmol of dysprosium chloride hexahydrate and place them in a 25 mL beaker; (2) Measure 3 mL of acetonitrile and 2 mL of distilled water with a graduated cylinder, pour them into a 25 mL beaker, stir with a glass rod, then add a stir bar and stir with a magnetic stirrer at room temperature for about half an hour. (3) Add one drop of concentrated nitric acid to a 25 mL beaker, then place it in an ultrasonic instrument and vibrate for ten minutes. (4) Remove the stir bar, pour the reaction system into the reactor liner, cover it and put in the iron sleeve, react in an oven at 130°C for 72 h, remove it and cool it to room temperature, filter it, wash it, and obtain the dysprosium complex [Dy(H3L)Cl3]·H2O.

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