A dual-ligand lanthanide metal-organic framework material and its preparation method

Abstract

This invention discloses a dual-ligand lanthanide metal-organic framework material and its preparation method. The dual-ligand lanthanide metal-organic framework material is applied to red, green, and white light emission. Lanthanide metal ions, 5-(4-carboxy-phenoxy)isophthalic acid, and 1,10-phenanthroline are dissolved in an appropriate amount of deionized water. Dilute nitric acid is added dropwise to adjust the pH value. The mixed solution is transferred to a sealed hydrothermal reactor and placed in a constant-temperature drying oven for hydrothermal reaction. The collected product is centrifuged, washed, and dried to finally obtain the Ln-MOF luminescent material. The red and green light emitting materials prepared by this invention exhibit high quantum efficiency, and the white light emitting material achieves white light emission under 365nm wavelength excitation. Phosphors made from this material, combined with silicone, and coated onto a 365nm LED chip can obtain white light with a high color rendering index and low color temperature.

Description

Technical Field

[0001] This invention belongs to the field of phosphor preparation technology, specifically relating to a dual-ligand lanthanide metal-organic framework (Ln-MOFs) material and its preparation method. Background Technology

[0002] Lanthanide metal-organic frameworks (Ln-MOFs) are the main research focus among luminescent MOF materials (LMOFs). Because Ln ions possess unfilled 4f orbitals, these 4f electrons can undergo ff or fd configuration transitions, exhibiting an extremely rich energy level transition pattern. This results in Ln-MOFs displaying unique optical properties, including high color purity, large Stokes shift values, visible color, and relatively long luminescence lifetime and unique monochromaticity resulting from ff transitions via the antenna effect. Consequently, they are widely used in white light-emitting diode (WLED) materials.

[0003] While traditional techniques can prepare white light emitting materials by doping with phosphors, these methods generally require phosphors to have high quenching temperatures, uniform particle sizes, ease of coating, and the ability to be excited by light sources, which makes them unsuitable for modern technology's requirements for white light materials. In contrast, luminescent rare-earth metal-organic framework materials prepared by doping with rare-earth ions have advantages such as strong color tunability, high quantum yield, and long luminescence lifetime, thus showing promising application prospects in the field of white light emitting materials.

[0004] Using MOFs as a matrix, blue-emitting organic ligands are selected and doped with green-emitting Tb. 3+ Ions and red-glowing Eu 3+ Ions, utilizing the antenna effect (ligand → Ln) 3+ The energy transfer process of ions (ions) has led to widespread interest in methods for Ln-MOFs to emit white light under the same ultraviolet excitation. The fabrication of WLEDs using synthesized Ln-MOFs offers the following advantages: 1) They are single-phase materials, eliminating the need for mixing multiple phosphors and simplifying preparation; 2) They exhibit red light emission, which can improve the color rendering index and lower the color temperature of WLEDs. Therefore, Ln-MOFs hold promise as a key area of ​​future WLED research. Summary of the Invention

[0005] This invention proposes a method for preparing Ln-MOFs white luminescent materials and their application in WLEDs on near-ultraviolet chips. Based on the first ligand 5-(4-carboxy-phenoxy)isophthalic acid, a second ligand 1,10-phenanthroline is added, and different lanthanide metal ion ratios are adjusted. The hydrothermal reaction is carried out in a closed, stainless steel-lined polytetrafluoroethylene-lined hydrothermal reactor in a constant-temperature forced-air drying oven. The resulting powder is centrifuged, washed, and dried to finally obtain white Ln-MOFs luminescent material powder.

[0006] The technical solution adopted in this invention has the following steps:

[0007] I. A high quantum yield green and red Ln-MOF luminescent material

[0008] The green Ln-MOF luminescent material is prepared using the formula Ln(cpioa)phen(Ln:Tb).

[0009] The red-light-emitting Ln-MOF material is prepared using the formula Ln(cpioa)phen(Ln:Eu).

[0010] This luminescent material covers the visible light range of green and red light respectively, and can emit bright green and red light when excited by ultraviolet light. It is a white powder with good crystallinity and uniform particles.

[0011] The dual-ligand Ln(cpiao)phen, which emits both red and green light, exhibits higher fluorescence intensity and quantum efficiency compared to the single-ligand Ln(cpiao).

[0012] II. A type of Ln-MOF white light emitting material:

[0013] The luminescent material is prepared by the formula LaTbEu(cpioa)phen(La 3+ :Tb 3+ Eu 3+ The luminescent material (ratio = 0.9740:0.0255:0.0005) covers the entire visible light range, including blue, green, and red light. When excited by ultraviolet light at a wavelength of 365nm, it emits bright white light and is a white powder with good crystallinity and uniform particle size. By combining it with silicone and coating it onto a 365nm LED chip for encapsulation, a bright white illumination can be achieved at a voltage of 3.0–3.4V.

[0014] Large proportion of La 3+ The introduction of this not only preserved and enhanced the blue light emission of the ligand, but also diluted Tb. 3+ and Eu 3+ The strong red and green light emission provides the possibility for the control of white light.

[0015] There are two different forms of energy transfer in MOFs: (1) energy transfer between two organic ligands, and (2) Tb 3 + Eu 3+ Energy transfer between them.

[0016] II. Preparation method of Ln-MOF luminescent materials, the steps of which are as follows:

[0017] 1) Place 5-(4-carboxy-phenoxy)isophthalic acid (H3cpioa), 1,10-phenanthroline (1,10-phen), and lanthanide metal ion salts (La(NO3)3·6H2O, Tb(NO3)3·6H2O and Eu(NO3)3·6H2O) in a reactor and add dilute nitric acid to adjust the pH value;

[0018] 2) Take the above mixed solution and stir it at room temperature for 30 minutes;

[0019] 3) Transfer the above solution to a stainless steel reactor lined with polytetrafluoroethylene and place it in a constant temperature drying oven for hydrothermal reaction. The reaction temperature is controlled at 120℃ and the reaction time is controlled at 72 hours.

[0020] 4) The reacted powder was washed by centrifugation with deionized water and anhydrous ethanol, and dried at 60°C for 24 hours to obtain single-phase Ln-MOFs material;

[0021] The inner lining of the hydrothermal reactor is made of polytetrafluoroethylene (PTFE) or PPL, while the outer shell is made of stainless steel. The pressure inside the reactor is controlled by the amount of solution added, and the reaction is carried out under high temperature and high pressure.

[0022] The obtained white powder particles emitted green, red, and white light when excited at 322 nm, 325 nm, and 365 nm, respectively.

[0023] III. Application of Single-Phase Ln-MOFs Luminescent Materials in White LEDs

[0024] The white powder has fine and uniform particles, good dispersibility, and high crystallinity. It exhibits a broad blue emission peak, a narrow green emission peak, and a sharp red emission spectrum in the range of 400–650 nm.

[0025] The light-emitting device obtained by coating Ln-MOF luminescent materials with silicone and encapsulating them on a 365nm LED chip can emit white light (color rendering index: 85.4, color temperature: 4415K) at a voltage of 3.0 to 3.4V.

[0026] The fabrication method of WLED devices includes the following steps:

[0027] 1) Place the silicone gel on a clean glass plate;

[0028] 2) Weigh the Ln-MOFs phosphor using an analytical balance, and mix the weighed phosphor evenly with the organosilicone.

[0029] 3) Coat the mixed gel-like substance onto a 365nm LED chip;

[0030] 4) Place the coated LEDs in an oven and place them at 120°C for two hours to cure.

[0031] The beneficial effects of this invention are:

[0032] 1) This invention uses a simple hydrothermal synthesis method to prepare a novel mixed Ln-MOFs material powder with white light emission. The powder material has fine and uniform particles, good crystallinity, and emits an emission spectrum in the visible light range including blue, green and red light. Under ultraviolet light excitation at a wavelength of 365nm, the material can emit bright white light.

[0033] 2) The white phosphor produced by the method of the present invention can be applied to LED chips excited by 365nm ultraviolet light to produce white LEDs with high color rendering index (85.4) and low color temperature (4415K). Attached Figure Description

[0034] Figure 1 Here is a schematic diagram of the hydrothermal reactor structure: 1-fixing screw, 2-upper end cover, 3-reactor body, 4-sealing gasket, 5-lower end cover, 6-inner liner cover, 7-inner liner;

[0035] Figure 2 The XRD patterns of the products La(cpioa)phen, Tb(cpioa)phen, Eu(cpioa)phen and LaTbEu(cpioa)phen obtained in Example 1 are shown below.

[0036] Figure 3 It is a simulated structure of Ln(cpioa)phen-MOFs;

[0037] Figure 4 The infrared spectra of the products La(cpioa)phen, Tb(cpioa)phen, Eu(cpioa)phen and LaTbEu(cpioa)phen obtained in Example 1 are shown.

[0038] Figure 5 The X-ray photoelectron spectra of the product LaTbEu(cpioa)phen obtained in Example 1 are: (a) full spectrum, (b) La 3d, (c) Tb 3d, and (d) Eu 3d.

[0039] Figure 6 The X-ray photoelectron spectrum of the product LaTbEu(cpioa)phen obtained in Example 1: C1s, O1s, and N1s;

[0040] Figure 7The thermogravimetric analysis diagrams of the products obtained in Example 1 are: (a) La(cpioa)phen, (b) Tb(cpioa)phen, (c) Eu(cpioa)phen, and (d) LaTbEu(cpioa)phen.

[0041] Figure 8 The fluorescence spectra and corresponding CIE spectra of the products Tb(cpioa) and Tb(cpioa)phen, Eu(cpioa) and Eu(cpioa)phen obtained in Example 1 are shown.

[0042] Figure 9 The CIE spectra of the products obtained in Example 1 are La(cpioa)phen, Tb(cpioa)phen, and Eu(cpioa)phen.

[0043] Figure 10 This is the energy transfer model of the product obtained in Example 1;

[0044] Figure 11 This is the luminescence spectrum of the product LaTbEu(cpioa)phen obtained in Example 1;

[0045] Figure 12 The corresponding CIE spectrum of the product obtained in Example 1;

[0046] Figure 13 This is the WLED photoelectric parameter emission spectrum of the product obtained in Example 1. Specific implementation methods

[0047] like Figure 1 The image shows a stainless steel reactor used for hydrothermal reactions according to the present invention. The reactor body 3 has an inner liner 7 made of polytetrafluoroethylene (PTFE) or PPL material. An inner liner cover 6 is provided on the upper surface of the inner liner 7. Above the inner liner cover 6 are a lower end cover 5 and an upper end cover 2, which are installed by fixing screws 1. The lower end cover 5 and the reactor body 3 are sealed by a sealing gasket 4. In this invention, the prepared reaction solution is transferred to the hydrothermal reactor. Under high temperature and pressure, the solute molecules react to ultimately generate MOF powder. The luminescent powder has the formula LaTbEu(cpioa)phen. This powder material emits bright white light when excited by 365nm ultraviolet light. It is encapsulated with an LED chip to form a light-emitting device, achieving bright white illumination at a voltage of 3.0–3.4V.

[0048] Example 1:

[0049] Preparation of Ln-MOF luminescent materials:

[0050] Dissolve 8.6602 g of La(NO3)3·6H2O in 100 mL of deionized water to prepare a La solution with a molar concentration of 0.2 mol / L. 3+Solution. Then, dissolve 9.0606 g and 2.7182 g of Tb(NO3)3·6H2O in 100 mL of deionized water to prepare Tb solutions with molar concentrations of 0.2 mol / L and 0.06 mol / L, respectively. 3+ Solution. Finally, 8.9200 g and 4.46 mg of Eu(NO3)3·6H2O were dissolved in 100 mL of deionized water to prepare La solutions with molar concentrations of 0.2 mol / L and 0.0001 mol / L, respectively. 3+ Solution. Dissolve 6.62 mL of concentrated nitric acid in 100 mL of deionized water to prepare a dilute nitric acid solution with a molar concentration of 1 mol / L.

[0051] 1) Preparation of La(cpioa)phen: Take 0.6 mmol of 0.2 mol / L La 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0052] 2) Preparation of Tb(cpioa)phen: Take 0.6 mmol of 0.2 mol / L Tb 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0053] 3) Preparation of Eu(cpioa)phen: Take 0.6 mmol of 0.2 mol / L Eu 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid and 0.0541 g of 1,10-phenanthroline, which are 0.3 mmol each.

[0054] 4) Preparation of LaTbEu(cpioa)phen: Take 0.5844 mmol of 0.2 mol / L La 3+ 2.922 mL of solution was prepared, and 0.0153 mmol of 0.06 mol / L Tb was taken. 3+ 0.26 mL of solution, take 0.0003 mmol of 0.0001 mol / L La 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0055] Four groups of samples were dissolved in beakers containing 50 mL of deionized water and stirred. During stirring, approximately 1 mol / L dilute nitric acid solution was added dropwise to adjust the pH of the mixed solution to 6.0. Stirring continued for approximately 30 minutes. After stirring, the mixed solutions were transferred to 100 mL stainless steel reactors lined with polytetrafluoroethylene (PTFE), with a filling density of approximately 60%. The three reactors were placed in a constant-temperature drying oven, and the reaction time was set to 72 hours at 120°C for hydrothermal reaction. After the reaction, the samples were centrifuged with deionized water and washed three times. The centrifuged products were then placed in a constant-temperature drying oven and dried at 60°C for 24 hours. Finally, four white crystalline materials with uniform particle size, La(cpioa)phen, Tb(cpioa)phen, Eu(cpioa)phen, and LaTbEu(cpioa)phen, were obtained.

[0056] Figure 2 The product obtained in this embodiment is Ln(cpioa)phen(Ln:La). 3+ ,Tb 3+ and Eu 3+ XRD patterns of Ln(cpioa)phen and LaTbEu(cpioa)phen were obtained, and the XRD patterns of the prepared samples were consistent with the simulated patterns. Adding the auxiliary ligand 1,10-phen improved the crystallinity of the given samples. This is likely because, during the coordination process between Ln(cpioa) and 1,10-phen, the N atom in 1,10-phen may substitute for the N atom in Ln. 3+ Ion-coordinated water molecules expand the conjugated system of MOFs and increase crystallinity.

[0057] Figure 3 The simulated structures of Ln(cpioa)phen-MOFs based on XRD pattern analysis are shown.

[0058] like Figure 4 As shown, 3070cm -1 The nearby peak is attributed to the CH stretching vibration on the benzene ring of the ligand. In Ln(cpioa)phen, at 1723 cm⁻¹... -1 The absence of an absorption peak indicates that H3cpioa has been completely deprotonated to cpioa. 3+ and with Ln 3+ Coordination. 1,10-phen at 1421 cm⁻¹ -1 The disappearance of the C=N tensile vibration peak at this point may be due to the interaction between nitrogen atoms in 1,10-phen and Ln. 3 + Caused by ion coordination. In conjunction with Ln... 3+ After ion coordination, the asymmetry (ν) of -COOH as ) and symmetry (ν) sThe tensile vibration peaks were respectively from 1280 cm⁻¹ -1 Moved to 1387cm -1 and 1423cm -1 Up to 1536cm -1 Therefore, it can be concluded that the Ln ion successfully coordinates with the O and N atoms in the Ln(cpio)phen-MOF framework.

[0059] Figure 5 , Figure 6 This is the X-ray photoelectron spectrum of the MOF powder. The XPS results indicate that H3cpioa binds to La in both ionic and covalent ways. 3+ 、Tb 3+ and Eu 3+ In this combination, no redox reaction occurs during coordination, and the C1s, O1s, and N1s spectra confirm that La 3+ 、Tb 3+ and Eu 3+ It bonds with the O and N atoms on -COO- and C=N in the ligand.

[0060] Figure 7 Thermogravimetric analysis (TG) plots of the Ln-MOFs powder are shown. As shown, all given samples underwent similar weight loss processes: the first weight loss step (12.57%) occurred between 25 and 112 °C, which likely corresponds to the removal of surface water molecules. The second weight loss step (13.43%) occurred between 112 and 439 °C, which likely corresponds to the removal of structural water molecules within the framework. The third weight loss step (45.74%) occurred between 439 and 517 °C, and the weight loss is likely due to framework collapse (47.72%). The TG results indicate that the prepared Ln-MOFs possess sufficiently good thermal stability for WLED applications.

[0061] Figure 8 The fluorescence spectra of Tb(cpioa) and Tb(cpioa)phen, Eu(cpioa) and Eu(cpioa)phen, and their corresponding CIE spectra are shown in Table 1. Table 1 below presents the fluorescence intensity and quantum efficiency values ​​for Tb(cpioa) and Tb(cpioa)phen, Eu(cpioa) and Eu(cpioa)phen.

[0062] Table 1

[0063]

[0064] As shown in the table above, dual-ligand Ln-MOFs exhibit significantly higher emission intensities compared to single-ligand Ln-MOFs. The emission intensity and quantum efficiency of Tb(cpioa)phen are approximately 21 times and 5 times higher than those of Tb(cpioa), respectively. The emission intensity and quantum efficiency of Eu(cpioa)phen are approximately 34 times and 36 times higher than those of Eu(cpioa), respectively. The inset shows that the luminance of dual-ligand Ln(cpioa)phen is considerably higher than that of single-ligand Ln(cpioa).

[0065] Weigh 0.06g of the obtained LaTbEu(cpioa)phen phosphor using weighing paper. Then weigh 0.5g of silicone rubber into a glass plate, and pour the weighed LaTbEu(cpioa)phen onto the silicone rubber. Use a glass rod to stir and mix the phosphor and silicone rubber evenly. Coat the mixed material onto a 365nm LED chip, and dry it in a 120℃ constant temperature drying oven for two hours. After curing, a WLED is obtained.

[0066] Figure 9 The CIE chromaticity diagrams of La(cpioa)phen, Tb(cpioa)phen, and Eu(cpioa)phen show that they fall into the blue, green, and red regions, respectively. Therefore, by further adjusting the La(cpioa)phen... 3+ 、Tb 3+ and Eu 3+ The ratio of [specific parameters] can achieve white light emission.

[0067] Figure 10 This is a model simulating energy transfer within LaTbEu(cpioa)phen. For the organic ligands in LaTbEu(cpioa)phen, energy transfer occurs via two pathways: (i) through an energy transfer process, energy is transferred from the lowest singlet state (S1) of H3cpioa to S1 of 1,10-phen, then from S1 of 1,10-phen to the lowest triplet state (T1) of 1,10-phen, and finally to Ln. 3+ (ii) Through the ISC process, energy is transferred from S1 of H3cpioa to T1 of H3cpioa, then from T1 of H3cpioa to T1 of 1,10-phen, and finally to Ln. 3+ The emission energy level; for organic ligands and metal ions in LaTbEu(cpioa)phen, a portion of the energy absorbed by the organic ligand is directly transferred to Tb. 3+ and Eu 3+ Ions, Tb 3+ Then transfer some energy to Eu 3+ Therefore, only a small amount of Eu is needed.3+ This allows you to modulate white light.

[0068] Depend on Figure 11 It is known that the luminescent material prepared by this invention can emit characteristic peaks of Tb and Eu;

[0069] Figure 12 The image shows the CIE chromaticity diagram of the LaTbEu(cpioa)phen, with coordinates (0.323, 0.343), which is very close to pure white light (0.333, 0.333). This confirms the successful synthesis of Ln-MOF white phosphors.

[0070] Figure 13 This is a graph showing the photoelectric performance parameters of the WLED. It can be seen that the WLED made with this phosphor and near-ultraviolet LED chip has a high color rendering index of 85.4 and a low color temperature of 4415K.

[0071] Example 2:

[0072] Preparation of Ln-MOF luminescent materials:

[0073] Dissolve 8.6602 g of La(NO3)3·6H2O in 100 mL of deionized water to prepare a La solution with a molar concentration of 0.2 mol / L. 3+ Solution. Then, dissolve 9.0606 g and 2.7182 g of Tb(NO3)3·6H2O in 100 mL of deionized water to prepare Tb solutions with molar concentrations of 0.2 mol / L and 0.06 mol / L, respectively. 3+ Solution. Finally, 8.9200 g and 4.46 mg of Eu(NO3)3·6H2O were dissolved in 100 mL of deionized water to prepare La solutions with molar concentrations of 0.2 mol / L and 0.0001 mol / L, respectively. 3+ Solution. Dissolve 6.62 mL of concentrated nitric acid in 100 mL of deionized water to prepare a dilute nitric acid solution with a molar concentration of 1 mol / L.

[0074] 1) Preparation of La(cpioa)phen: Take 0.6 mmol of 0.2 mol / L La 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid and 0.0541 g of 1,10-phenanthroline, which are 0.3 mmol each.

[0075] 2) Preparation of Tb(cpioa)phen: Take 0.6 mmol of 0.2 mol / L Tb 3+ Add 3 mL of solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0076] 3) Preparation of Eu(cpioa)phen: Take 0.6 mmol of 0.2 mol / L Eu 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid and 0.0541 g of 1,10-phenanthroline, which are 0.3 mmol each.

[0077] 4) Preparation of LaTbEu(cpioa)phen: Take 0.5844 mmol of 0.2 mol / L La 3+ 2.922 mL of solution was prepared, and 0.0153 mmol of 0.06 mol / L Tb was taken. 3+ 0.26 mL of solution, take 0.0003 mmol of 0.0001 mol / L La 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0078] Four samples were dissolved in beakers containing 35 mL of deionized water and stirred. During stirring, approximately 1 mol / L dilute nitric acid solution was added dropwise to adjust the pH of the mixed solution to 6.0. Stirring continued for approximately 30 minutes. After stirring, the mixed solutions were transferred to 100 mL stainless steel reactors lined with polytetrafluoroethylene (PTFE), with a filling density of approximately 50%. The three reactors were placed in a constant-temperature drying oven, and the reaction time was set to 72 hours at 120°C for hydrothermal reaction. After the reaction, the samples were centrifuged with deionized water and washed three times. The centrifuged products were then placed in a constant-temperature drying oven and dried at 60°C for 24 hours. Finally, four white crystalline materials with uniform particle size, namely La(cpioa)phen, Tb(cpioa)phen, Eu(cpioa)phen, and LaTbEu(cpioa)phen, were obtained.

[0079] Example 3:

[0080] Preparation of Ln-MOF luminescent materials:

[0081] Dissolve 8.6602 g of La(NO3)3·6H2O in 100 mL of deionized water to prepare a La solution with a molar concentration of 0.2 mol / L. 3+ Solution. Then, dissolve 9.0606 g and 2.7182 g of Tb(NO3)3·6H2O in 100 mL of deionized water to prepare Tb solutions with molar concentrations of 0.2 mol / L and 0.06 mol / L, respectively. 3+ Solution. Finally, 8.9200 g and 4.46 mg of Eu(NO3)3·6H2O were dissolved in 100 mL of deionized water to prepare La solutions with molar concentrations of 0.2 mol / L and 0.0001 mol / L, respectively.3+ Solution. Dissolve 6.62 mL of concentrated nitric acid in 100 mL of deionized water to prepare a dilute nitric acid solution with a molar concentration of 1 mol / L.

[0082] 1) Preparation of La(cpioa)phen: Take 0.6 mmol of 0.2 mol / L La 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid and 0.0541 g of 1,10-phenanthroline, which are 0.3 mmol each.

[0083] 2) Preparation of Tb(cpioa)phen: Take 0.6 mmol of 0.2 mol / L Tb 3+ Add 3 mL of solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0084] 3) Preparation of Eu(cpioa)phen: Take 0.6 mmol of 0.2 mol / L Eu 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid and 0.0541 g of 1,10-phenanthroline, which are 0.3 mmol each.

[0085] 4) Preparation of LaTbEu(cpioa)phen: Take 0.5844 mmol of 0.2 mol / L La 3+ 2.922 mL of solution was prepared, and 0.0153 mmol of 0.06 mol / L Tb was taken. 3+ 0.26 mL of solution, take 0.0003 mmol of 0.0001 mol / L La 3+ Take 3 mL of the solution, and then weigh out 0.0901 g of 5-(4-carboxy-phenoxy)isophthalic acid (0.3 mmol) and 0.0541 g of 1,10-phenanthroline.

[0086] Four samples were dissolved in beakers containing 50 mL of deionized water and stirred. During stirring, approximately 1 mol / L dilute nitric acid solution was added dropwise to adjust the pH of the mixed solution to 6.0. Stirring continued for approximately 30 minutes. After stirring, the mixed solutions were transferred to 100 mL stainless steel reactors lined with polytetrafluoroethylene (PTFE), with a filling density of approximately 60%. The three reactors were placed in a constant-temperature drying oven, and the reaction time was set to 72 hours at 130°C for hydrothermal reaction. After the reaction, the samples were centrifuged with deionized water and washed three times. The centrifuged products were then placed in a constant-temperature drying oven and dried at 60°C for 24 hours. Finally, four white crystalline materials with uniform particle size, La(cpioa)phen, Tb(cpioa)phen, Eu(cpioa)phen, and LaTbEu(cpioa)phen, were obtained.

[0087] The specific test results of the prepared Ln-MOFs are similar to those of Example 1.

Claims

1. A dual-ligand lanthanide metal-organic framework material emitting green, red, or white light, characterized in that, The aforementioned dual-ligand lanthanide metal-organic framework material is Ln(cpiao)phen, wherein the red-emitting dual-ligand Ln(cpiao)phen is Eu(cpioa)phen, the green-emitting dual-ligand Ln(cpiao)phen is Tb(cpioa)phen, and the white-emitting dual-ligand Ln(cpiao)phen is LaTbEu(cpioa)phen; The first and second ligands in the dual ligands are 5-(4-carboxy-phenoxy)isophthalic acid H3cpioa and 1,10-phenanthroline 1,10-phen; By adjusting La 3+ 、Tb 3+ and Eu 3+ The ion ratio can be adjusted to control the emission color of the material, exhibiting white light emission in lanthanide metal-organic framework materials with dual ligands. 3+ 、Tb 3+ and Eu 3+ The molar ratio of the ions is 0.9740:0.0255:0.0005; LaTbEu(cpioa)phen emits white light when excited at a wavelength of 365nm. The fluorescence intensity of the green-emitting Tb(cpioa)phen is 5.3 x 10⁻⁶. 5 The quantum efficiency reached 15.43%, and the fluorescence intensity of the red-emitting Eu(cpioa)phen was 9.4 x 10⁻¹⁰. 5 The quantum efficiency reaches 36.37%; The preparation method of the dual-ligand lanthanide metal-organic framework material includes the following steps: Step 1: Prepare lanthanide ion solution: Weigh an appropriate amount of lanthanide metal ion salt, dissolve it in deionized water, and stir to obtain lanthanide ion solution; Step 2: Dissolve the lanthanide ion solution prepared in Step 1 and the two organic small molecule ligands in deionized water, and stir and mix them at room temperature. During stirring, add 1 mol / L dilute nitric acid dropwise to adjust the pH of the mixed solution. In step 2, the two small organic molecule ligands are 5-(4-carboxy-phenoxy)isophthalic acid and 1,10-phenanthroline, and the molar ratio of 5-(4-carboxy-phenoxy)isophthalic acid, 1,10-phenanthroline and the metal central ion is 1:1:

2. Step 3: Transfer the mixed solution from Step 2 to a stainless steel reactor lined with polytetrafluoroethylene and place it in a constant temperature drying oven for hydrothermal reaction. Step 4: Wash the powder after the reaction in Step 3 with deionized water, and then dry it to obtain Ln(cpiao)phen luminescent material.

2. A light-emitting device fabricated using the dual-ligand lanthanide metal-organic framework material as described in claim 1, characterized in that: A light-emitting device is obtained by coating a white light-emitting phosphor LaTbEu(cpioa)phen with silicone and encapsulating it on a 365nm ultraviolet LED chip. The device emits bright white light at a voltage of 3.0-3.4V, with a color rendering index of 85.4 and a color temperature of 4415K.

3. The method for preparing the dual-ligand lanthanide metal-organic framework material with green, red, or white light emission as described in claim 1, characterized in that, Includes the following steps: Step 1: Prepare lanthanide ion solution: Weigh an appropriate amount of lanthanide metal ion salt, dissolve it in deionized water, and stir to obtain lanthanide ion solution; Step 2: Dissolve the lanthanide ion solution prepared in Step 1 and the two organic small molecule ligands in deionized water, and stir and mix them at room temperature. During stirring, add 1 mol / L dilute nitric acid dropwise to adjust the pH of the mixed solution. Step 3: Transfer the mixed solution from Step 2 to a stainless steel reactor lined with polytetrafluoroethylene and place it in a constant temperature drying oven for hydrothermal reaction. Step 4: Wash the powder after the reaction in Step 3 with deionized water, and then dry it to obtain Ln(cpiao)phen luminescent material; When preparing dual-ligand lanthanide metal-organic framework materials with green light emission: The method for preparing the lanthanide ion solution in step 1 is as follows: Weigh an appropriate amount of Tb(NO3)3·6H2O, dissolve it in deionized water, stir, and prepare a 0.3 mol / L Tb solution. 3+ ; When preparing dual-ligand lanthanide metal-organic framework materials with red light emission: The method for preparing the lanthanide ion solution in step 1 is as follows: Weigh an appropriate amount of Eu(NO3)3·6H2O, dissolve it in deionized water, stir, and prepare a 0.3 mol / L Tb solution. 3+ ; When preparing dual-ligand lanthanide metal-organic framework materials with white light emission: The method for preparing the lanthanide ion solution in step 1 is as follows: Weigh appropriate amounts of La(NO3)3·6H2O, Tb(NO3)3·6H2O, and Eu(NO3)3·6H2O, dissolve them in deionized water, stir, and prepare 0.2 mol / L La solutions respectively. 3+ 0.06 mol / L Tb 3+ and 0.0001 mol / L Eu 3+ ; In step 2, the two small organic molecule ligands are 5-(4-carboxy-phenoxy)isophthalic acid and 1,10-phenanthroline, respectively. The molar ratio of 5-(4-carboxy-phenoxy)isophthalic acid, 1,10-phenanthroline, and the metal central ion is 1:1:

2. The metal central ion La... 3+ 、Tb 3+ and Eu 3+ The molar ratio is 0.9740:0.0255:0.0005.

4. The method for preparing the dual-ligand lanthanide metal-organic framework material according to claim 3, characterized in that, In step 2, the pH of the mixed solution is adjusted to 5-6 using dilute nitric acid.

5. The method for preparing the dual-ligand lanthanide metal-organic framework material according to claim 3, characterized in that, In step 3, the stainless steel reactor liner is made of polytetrafluoroethylene or PPL material, the outer shell is made of stainless steel material, and the filling amount of the mixed solution accounts for 45% to 65% of the reactor liner volume; the hydrothermal reaction temperature is controlled at 120℃, and the reaction time is controlled at 72 hours.

6. The method for preparing the dual-ligand lanthanide metal-organic framework material according to claim 3, characterized in that, In step 4, the drying conditions are 60°C for 24 hours.

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