Method for regulating and controlling luminescence of triphenylamine metal-organic framework material based on mixed ligand strategy

Abstract

The invention discloses a method for regulating and controlling luminescence of a triphenylamine metal-organic framework material based on a mixed ligand strategy, and the method specifically comprises the following steps: selecting an organic chromophore with two or more emission peaks, and introducing a series of second ligands with the same or similar luminescence; and preparing a metal-organic framework (MOFs) material by jointly using the organic chromophore and any second ligand as an organic ligand. And the conformation of the organic chromophore is changed by introducing the second ligand, so that the local excited state and the intramolecular charge transfer state of the organic chromophore are regulated and controlled, and the wide-range adjustment of the emission spectrum of the MOFs material is realized. The series of MOFs materials show a cyan-to-orange chromatographic range under the irradiation of an ultraviolet lamp, the preparation and synthesis process is simple, and the second ligand can also transfer energy to the organic chromophore to promote the improvement of quantum efficiency.

Description

Technical Field

[0001] The present invention relates to the field of luminescent materials, and particularly to a method for regulating the luminescence of triphenylamine-based metal-organic framework materials based on a mixed ligand strategy. Background Art

[0002] Due to their unique optical properties, luminescent materials exhibit great application potential in many fields. In the fields of display technology and lighting, new luminescent materials such as perovskites and quantum dots have received extensive attention due to their high quantum efficiency and wide color gamut range. The application of luminescent materials has promoted the gradual replacement of traditional light sources by more energy-efficient and environmentally friendly light-emitting diodes (LEDs). In the biomedical field, luminescent materials provide new tools for in vivo imaging and treatment. With the development of wearable technology, luminescent materials can also be used for health monitoring, information display, and even treatment. From traditional lighting and display technologies to emerging biomedical and wearable devices, the versatility and high quantum efficiency of luminescent materials make them an indispensable part of modern technology.

[0003] It is worth noting that the color tunability of luminescent materials is a key property in multiple application fields. However, according to Kasha's rule, for molecules in multiple states, photons can only be emitted from the lowest excited state. Achieving continuous tunability of luminescence color is a challenging task. Organic chromophores have unique advantages in luminescent materials due to their rich variety and wide emission range, and a large number of studies have been carried out to regulate the photophysical properties of organic chromophores. For example, their luminescent properties can be changed through chemical synthesis, but the synthesis process is usually complex. Another common strategy is to introduce responsive groups to induce changes in the molecular structure, but there are problems such as poor reversibility and limited structural selectivity. Recently, changing the conformation of molecules has been considered a more promising and simpler method, attracting extensive attention.

[0004] Changes in molecular conformation can affect the electron transition path in the excited state, thereby changing the luminescent properties of organic chromophores. However, there are still two challenges in the preparation of organic crystal materials with continuously tunable luminescence. (i) Conformational diversity is greatly restricted in the solid state (especially in the crystalline phase), and the tunability of luminescence color is weakened, limiting its application range. (ii) Traditional organic chromophores are affected by the aggregation-caused quenching effect (ACQ), and the quantum efficiency is very low.

[0005] The MOF materials of the present invention adopt a mixed ligand strategy and are self-assembled from organic chromophores, dicarboxylic acids as the second ligands, and metal ions or metal clusters. Without changing the metal ions and organic chromophores, the conformation of the organic chromophores can be changed only by simply changing the second ligands, thereby regulating their local excited states and intramolecular charge transfer states, and successfully realizing continuous tunability of the luminescence of the MOF materials. In addition, the efficient and directional energy transfer from the second ligands to the organic chromophores can effectively improve the quantum efficiency. By using a one-step synthesis preparation method, the synthesis products can be controlled and predicted, and it is easy to form a highly connected three-dimensional infinite network structure. A series of synthesized MOF materials have good stability and high quantum efficiency, and can be used as a material with continuously tunable luminescence, and have potential applications in the fields of sensing, bioimaging, display lighting, etc. Summary of the Invention

[0006] To solve the problems existing in the prior art, the present invention proposes a method for regulating the luminescence properties of triphenylamine-based metal-organic framework materials based on a mixed ligand strategy, realizing rich color tunability. In addition, the stable rigid structure and the energy transfer between the luminescent functional units can effectively improve the quantum efficiency.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A method for regulating the luminescence of triphenylamine-based metal-organic framework materials based on a mixed ligand strategy, selecting an organic chromophore with two or more emission peaks, selecting a series of second ligands with the same or similar luminescence, using any second ligand and the organic chromophore as organic ligands to prepare MOF materials, and regulating the luminescence of the prepared MOF materials by changing the second ligands; the organic chromophore adopts triphenylamine derivatives, and the material is called triphenylamine-based metal-organic framework materials.

[0009] Further, the organic chromophore is tris(4-(pyridin-4-yl)phenyl)amine; the second ligand is specifically a second ligand with a luminescence range of 334 nm to 371 nm in solution.

[0010] Further, the second ligand includes: terephthalic acid with the structural formula (a), 2-chloroterephthalic acid with the structural formula (b), 2-bromoterephthalic acid with the structural formula (c), 2-fluoroterephthalic acid with the structural formula (d), 2,5-dichloroterephthalic acid with the structural formula (e), 2,5-dibromoterephthalic acid with the structural formula (f), 2,5-difluoroterephthalic acid with the structural formula (g), isophthalic acid with the structural formula (h), 2-chloroisophthalic acid with the structural formula (i), 5-bromoisophthalic acid with the structural formula (g), 2-fluoroisophthalic acid with the structural formula (k), phthalic acid with the structural formula (l), 4,4'-biphenyldicarboxylic acid with the structural formula (m), 2,2'-biphenyldicarboxylic acid with the structural formula (n), 4,4'-diphenyletherdicarboxylic acid with the structural formula (o), 2,5-furandicarboxylic acid with the structural formula (p), 2,6-pyridine-dicarboxylic acid with the structural formula (q), 3,5-pyridinedicarboxylic acid with the structural formula (r).

[0011]

[0012] Further, the preparation method of the MOFs material includes the following:

[0013] Dissolve the metal salt, any second ligand and the organic chromophore in a solvent, ultrasonically mix them evenly, then keep the reaction at 85 °C for 24 - 72 h, naturally cool to room temperature, wash and then filter and dry to obtain the MOFs material. The washing is carried out with an organic solvent, and the organic solvent is specifically N,N-dimethylformamide or N,N-dimethylacetamide.

[0014] Further, the ratio of the metal salt, the second ligand, the organic chromophore and the solvent is (0.08 - 0.2 mmol):(0.08 - 0.2 mmol):(0.04 - 0.1 mmol):(4 - 16 ml).

[0015] Further, the solvent is any one or several of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, methanol, deionized water, mixed in any ratio.

[0016] Further, the metal salt is one of zinc nitrate, zinc acetate, cadmium nitrate and cobalt chloride.

[0017] Further, five MOFs materials are combined to achieve tunable luminescence from cyan-green to yellow to orange. The combination sequence is Zn-IPA-TPPA, Zn-BPDC-TPPA, Zn-OBA-TPPA, Zn-BDC-TPPA, Zn-FDA-TPPA in turn.

[0018] Further, the five MOF materials are prepared by using one of the five second ligands, tris(4-(pyridin-4-yl)phenyl)amine, and zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O);

[0019] The five second ligands are isophthalic acid (H 2 IPA), biphenyldicarboxylic acid (H 2 BPDC), 4,4'-oxydibenzoic acid (H 2 OBA), terephthalic acid (H 2 BDC), and 2,5-furandicarboxylic acid (H 2 FDA).

[0020] A metal-organic framework material is prepared by using a metal salt, a second ligand, and an organic chromophore. The metal salt is zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O);

[0021] The second ligand is one of 4,4'-oxydibenzoic acid (H 2 OBA), terephthalic acid (H 2 BDC), and 2,5-furandicarboxylic acid (H 2 FDA);

[0022] The organic chromophore is tris(4-(pyridin-4-yl)phenyl)amine (TPPA).

[0023] The specific beneficial effects of the present invention are as follows:

[0024] 1. The MOF materials used in the present invention exhibit rich color tunability due to their specific structures and compositions. Especially when combined with organic chromophores with rich conformations, the emission chromatographic range is further expanded. In addition, the stable rigid structure and the energy transfer between luminescent functional units can effectively improve the quantum efficiency.

[0025] 2. In the present invention, for the organic chromophore TPPA molecule, the emissions are mainly at about 455 nm and 530 nm under different wavelength excitations, indicating that there are two excited states for the emission of TPPA. The former belongs to the local excited state, and the latter belongs to the intramolecular charge transfer state. In the present invention, the conformation of the organic chromophore can be changed only by simply changing the second ligand, thereby regulating its local excited state and intramolecular charge transfer state, and successfully realizing continuous tunability of the luminescence of the MOF materials. In addition, the efficient and directional energy transfer from the second ligand to the organic chromophore can also effectively improve the quantum efficiency.

[0026] 3. The synthesis methods of the present invention all adopt a one-step synthesis method, with a simple preparation process. The reaction can be carried out at 85 °C without the need for a special environment of high temperature and high pressure.

[0027] 4. Compared with organic molecules, the MOFs materials of the present invention are a class of highly ordered crystalline materials. A series of highly connected crystal structures have been obtained in the present invention. For example, a three-dimensional infinite network structure formed by zinc ions, the organic ligand terephthalic acid, and the organic chromophore tris(4-(pyridin-4-yl)phenyl)amine, where the zinc ions are coordinated with the oxygen atoms of two surrounding terephthalic acids and the nitrogen atoms of two tris(4-(pyridin-4-yl)phenyl)amines.

[0028] 5. A series of MOFs materials synthesized in the present invention are formed by connecting metal ions or metal clusters with organic mixed ligands through coordination bonds, and have excellent thermal stability, and can maintain structural stability in a nitrogen atmosphere at 300 °C.

[0029] 6. Compared with organic molecules, the MOFs materials adopted in the present invention have rich luminescence sites, a wide range of luminescence wavelengths, and strong luminescence tunability. In the present invention, the absorption spectrum of the organic chromophore and the emission spectrum of the second ligand have good overlap, and effective energy transfer can be carried out to improve the quantum efficiency, which increases from 4.56% of the organic chromophore to about 20% of the MOFs materials.

[0030] 7. The present invention changes the conformation of the organic chromophore by introducing five second ligands, thereby regulating its local excited state and intramolecular charge transfer state, and realizing continuous tunability of the emission spectrum from cyan to yellow to orange after the sequential combination of five MOFs materials. Description of the Drawings

[0031] Figure 1 is the powder X-ray diffraction pattern in the method for regulating the luminescence of triphenylamine-based metal-organic framework materials based on the mixed ligand strategy according to an embodiment of the present invention;

[0032] Figure 2 is the structure and solid-state fluorescence spectrum of the organic chromophore in the method for regulating the luminescence of triphenylamine-based metal-organic framework materials based on the mixed ligand strategy according to an embodiment of the present invention;

[0033] Figure 3 is the schematic structural diagram of the dicarboxylic acid ligand in the method for regulating the luminescence of triphenylamine-based metal-organic framework materials based on the mixed ligand strategy according to an embodiment of the present invention;

[0034] Figure 4(a) is the fluorescence spectrum in the method for regulating the luminescence of triphenylamine-based metal-organic framework materials based on the mixed ligand strategy according to an embodiment of the present invention, realizing continuous adjustment of the luminescence of the MOFs materials by selecting five ligands;

[0035] Figure 4(b) is a comparison of the fluorescence spectra of TPPA, dicarboxylic acid ligand, and MOF crystals in an embodiment of the present invention. Detailed implementation mode

[0036] The following will further clarify the content of the present invention in combination with examples. However, these examples do not limit the protection scope of the present invention. Based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

[0037] Example 1:

[0038] Using zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O), isophthalic acid (H 2 IPA), and tris(4-(pyridin-4-yl)phenyl)amine (TPPA), an MOF material was synthesized by the solvothermal method. The specific synthesis route is as follows:

[0039] Dissolve 16.6 mg of isophthalic acid, 48.0 mg of tris(4-(pyridin-4-yl)phenyl)amine (TPPA), and 29.7 mg of zinc nitrate hexahydrate in 6 ml of N,N-dimethylformamide and 9 ml of deionized water. Ultrasonic until the solution is clear, place it in a 20 ml sealed glass bottle, react in a constant temperature oven at 85 °C for 72 h, naturally cool to room temperature, and wash the filtered solid with N,N-dimethylformamide repeatedly for many times. Dry to obtain light yellow block-shaped crystals, namely Zn-IPA-TPPA.

[0040] Determine its structural formula by an Oxford Xcalibur Gemini Ultra single crystal diffractometer. The test results show that the space group of this material is C1 2 / c 1(15), belonging to the monoclinic system, and the unit cell parameters are β = 96.744°, Z = 8. The experimental XRD and single crystal XRD simulation diagrams of Zn-IPA-TPPA are as shown in Figure 1 (a). This material is a three-dimensional infinite network structure formed by zinc ions, the organic ligand isophthalic acid, and the organic chromophore tris(4-(pyridin-4-yl)phenyl)amine. The zinc ion coordinates with two surrounding oxygen atoms and two nitrogen atoms.

[0041] The obtained Zn-IPA-TPPA is light yellow crystals in the shape of blocks. The high connection method results in high chemical stability, photostability, and thermal stability of this material. The quantum efficiency is increased from 4.56% of the organic chromophore to 12.39%.

[0042] Example 2:

[0043] Using zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O), 4,4'-biphenyldicarboxylic acid (H 2 BPDC), and tris(4-(pyridin-4-yl)phenyl)amine (TPPA), a MOF was synthesized by solvothermal method. The specific synthesis route is as follows:

[0044] Add 23.8 mg of zinc nitrate hexahydrate, 38.1 mg of tris(4-(pyridin-4-yl)phenyl)amine, 19.4 mg of 4,4'-biphenyldicarboxylic acid, 8 ml of N,N-dimethylacetamide, 4 ml of acetonitrile, and 4 ml of H 2 O into a 20 ml glass bottle. Ultrasonic until the solution is clear, heat to 85 °C and react for 72 h. Wash with N,N-dimethylacetamide and dry in air to obtain light yellow block crystals, namely Zn-BPDC-TPPA.

[0045] Its crystal structure was determined by an Oxford Xcalibur Gemini Ultra single crystal diffractometer. The test results show that the space group of this material is P1 21 / c 1(14), belonging to the monoclinic system, and the unit cell parameters are β = 97.857°, Z = 4. The experimental XRD and single crystal XRD simulation diagrams of Zn-BPDC-TPPA are as shown in Figure 1 (b). This material is a three-dimensional infinite network structure formed by zinc ions, the organic ligand 4,4'-biphenyldicarboxylic acid, and the organic chromophore tris(4-(pyridin-4-yl)phenyl)amine. Zinc ions have two coordination modes. One is to coordinate with two surrounding oxygen atoms and two nitrogen atoms, and the other is to form metal clusters through 4,4'-biphenyldicarboxylic acid, coordinating with eight oxygen atoms of four carboxylic acids and two nitrogen atoms of two tris(4-(pyridin-4-yl)phenyl)amines.

[0046] The obtained Zn-BPDC-TPPA is light yellow crystals in the shape of blocks. The high connection mode results in high chemical stability, photo-stability, and thermal stability of this material. The quantum efficiency is increased from 4.56% of the organic chromophore to 20.43%.

[0047] Example 3:

[0048] Using zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O) and 4,4'-oxydibenzoic acid (H 2Using zinc nitrate hexahydrate (Zn(NO 3 )

[0049] In a 20 ml glass bottle, 29.7 mg of zinc nitrate hexahydrate, 47.7 mg of tris(4-(pyridin-4-yl)phenyl)amine, 25.8 mg of 4,4'-oxydibenzoic acid, 10 ml of N,N-dimethylformamide and 5 ml of H 2 O were added. The mixture was sonicated until the solution became clear, then heated to 85 °C and reacted for 72 h. It was washed with N,N-dimethylformamide and dried in air to obtain light yellow block crystals, namely Zn-OBA-TPPA.

[0050] Its structure was determined by an Oxford Xcalibur Gemini Ultra single crystal diffractometer. The test results showed that the space group of this material was P1 21 / c 1(14), belonging to the monoclinic system, and the unit cell parameters were β = 98.465°, Z = 4. The experimental XRD and single crystal XRD simulation diagrams of Zn-OBA-TPPA are as shown in Figure 1 (c). This material is a three-dimensional infinite network structure formed by zinc ions, the organic ligand 4,4'-oxydibenzoic acid, and the organic chromophore tris(4-(pyridin-4-yl)phenyl)amine. Zinc ions are coordinated with two surrounding oxygen atoms and two nitrogen atoms.

[0051] The obtained Zn-OBA-TPPA is a light yellow crystal in the shape of a block. The high connection mode results in high chemical stability, photo-stability and thermal stability of this material.

[0052] Example 4:

[0053] Using zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O), terephthalic acid (H 2 BDC) and tris(4-(pyridin-4-yl)phenyl)amine (TPPA), an MOF material was synthesized by solvothermal method. The specific synthesis route is as follows:

[0054] 16.6 mg of terephthalic acid, 24.0 mg of tris(4-(pyridin-4-yl)phenyl)amine (TPPA), and 29.7 mg of zinc nitrate hexahydrate were dissolved in 5 ml of N,N-dimethylformamide. The mixture was sonicated until the solution became clear and then placed in a 20-ml sealed glass bottle. The reaction was carried out in a constant-temperature oven at 85 °C for 24 h. After natural cooling to room temperature, the obtained solid was repeatedly washed with N,N-dimethylformamide several times and then dried to obtain orange block-shaped crystals, namely Zn-BDC-TPPA.

[0055] Its structural formula was determined by an Oxford Xcalibur Gemini Ultra single-crystal diffractometer. The test results showed that the space group of this material was P1 21 / n 1(14), belonging to the monoclinic system, and the unit cell parameters were β = 93.402°, Z = 4. The experimental XRD and single-crystal XRD simulation diagrams of Zn-BDC-TPPA are as shown in Figure 1 (d). This material is a three-dimensional infinite network structure formed by zinc ions, the organic ligand terephthalic acid, and the organic chromophore tris(4-(pyridin-4-yl)phenyl)amine. There are two coordination modes for zinc ions. One is to coordinate with three surrounding oxygen atoms and two nitrogen atoms, and the other is to coordinate with four surrounding oxygen atoms and one nitrogen atom. The two zinc ions are bridged by terephthalic acid.

[0056] The obtained Zn-BDC-TPPA is an orange crystal in the shape of a block. The high connection mode endows this material with high chemical stability, photostability, and thermal stability. The quantum efficiency is increased from 4.56% of the organic chromophore to 17.79%.

[0057] Example 5:

[0058] Using zinc nitrate hexahydrate (Zn(NO 3 ) 2 ·6H 2 O), 2,5-furandicarboxylic acid (H 2 FDA), and tris(4-(pyridin-4-yl)phenyl)amine (TPPA), a MOF material was synthesized by the solvothermal method. The specific synthesis route is as follows:

[0059] Dissolve 15.6 mg of 2,5-furandicarboxylic acid, 23.8 mg of tris(4-(pyridin-4-yl)phenyl)amine (TPPA), and 29.7 mg of zinc nitrate hexahydrate in 5 ml of N,N-dimethylformamide, and ultrasonically homogenize until the solution becomes clear. Place it in a 20-ml sealed glass bottle and react in a constant-temperature oven at 85 °C for 24 h. Naturally cool it to room temperature, and repeatedly wash the obtained solid with N,N-dimethylformamide for multiple times. After drying, an orange block crystal, namely Zn-FDA-TPPA, is obtained.

[0060] Determine its structural formula by an Oxford Xcalibur Gemini Ultra single-crystal diffractometer. The test results show that the space group of this material is C1 2 / c 1(15), belonging to the monoclinic system, and the unit cell parameters are β = 111.331°, Z = 8. The experimental XRD and single-crystal XRD simulation diagrams of Zn-FDA-TPPA are as shown in Figure 1 (e). This material is a three-dimensional infinite network structure formed by zinc ions, the organic ligand 2,5-furandicarboxylic acid, and the organic chromophore tris(4-(pyridin-4-yl)phenyl)amine. There are two coordination modes of zinc ions. One is to coordinate with two surrounding oxygen atoms and two nitrogen atoms, and the other is to coordinate with four oxygen atoms of 2,5-furandicarboxylic acid, one nitrogen atom of tris(4-(pyridin-4-yl)phenyl)amine, and the oxygen atom of N,N-dimethylformamide.

[0061] The obtained Zn-FDA-TPPA is an orange crystal in the shape of a block. The high connection mode results in the material having high chemical stability, photostability, and thermal stability. The quantum efficiency is increased from 4.56% of the organic chromophore to 10.78%.

[0062] In the present invention, the solid-state fluorescence spectrum of the organic chromophore TPPA molecule is as shown in Figure 2 . Under excitation at different wavelengths, the emissions are mainly at about 455 nm and 530 nm, indicating that there are two excited states in the emission of TPPA. The former belongs to the local excited state, and the latter belongs to the intramolecular charge transfer state. Adopt the strategy of mixed ligands, and introduce a series of dicarboxylic acid ligands as the second ligands to jointly construct metal-organic framework materials with TPPA and metal ions. The schematic structural diagrams of the five representative dicarboxylic acid ligands selected are as shown in Figure 3 . The fluorescence spectra of the constructed MOFs materials are shown in Figure 4(a), and the chromatographic range extends from 478 nm to 600 nm, covering cyan to yellow to orange. It can be seen from Figure 4(b) that by comparing the fluorescence spectra of TPPA, the dicarboxylic acid ligand, and the MOFs crystal, there is a huge red shift in the emission of the MOFs crystal.

[0063] In the present invention, by simply changing the second ligand, the conformation of the organic chromophore can be changed, thereby regulating the local excited state and the intramolecular charge transfer state of the organic chromophore, and thus realizing continuous tunability of the emission of the luminescent metal-organic framework material. In addition, the efficient and directional energy transfer from the second ligand to the organic chromophore effectively improves the quantum efficiency of the luminescent material.

[0064] The above specific embodiments are used to explain the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the drawings. Therefore, all equivalent or modified implementations completed without departing from the spirit of the present invention fall within the protection scope of the present invention.

Claims

1. A method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy, characterized in that: An organic chromophore with two or more emission peaks is selected, and a series of second ligands with the same or similar luminescence are introduced. The organic chromophore and any second ligand are used as organic ligands to prepare MOFs materials, and the luminescence of the prepared MOFs materials is regulated by changing the second ligand.

2. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 1, characterized in that: The organic chromophore is tris(4-(pyridin-4-yl)phenyl)amine; The second ligand is specifically a second ligand that emits an emission wavelength of 334 nm to 371 nm in a solution.

3. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 1, characterized in that: The second ligand includes: terephthalic acid with structural formula (a), 2-chloroterephthalic acid with structural formula (b), 2-bromoterephthalic acid with structural formula (c), 2-fluoroterephthalic acid with structural formula (d), 2,5-dichloroterephthalic acid with structural formula (e), 2,5-dibromoterephthalic acid with structural formula (f), 2,5-difluoroterephthalic acid with structural formula (g), isophthalic acid with structural formula (h), 2-chloroisophthalic acid with structural formula (i) Formic acid, 5-bromoisophthalic acid of structural formula (g), 2-fluoroisophthalic acid of structural formula (k), phthalic acid of structural formula (l), 4,4'-biphenyldicarboxylic acid of structural formula (m), 2,2'-biphenyldicarboxylic acid of structural formula (n), 4,4'-diphenyletherdicarboxylic acid of structural formula (o), 2,5-furandicarboxylic acid of structural formula (p), 2,6-pyridinedicarboxylic acid of structural formula (q), 3,5-pyridinedicarboxylic acid of structural formula (r); 4. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 1, characterized in that: The preparation method of the MOFs material comprises the following steps: The metal salt, any second ligand and the organic chromophore are dissolved in a solvent, ultrasonically mixed, kept reacting for 24 to 72 hours in an environment of 85° C., naturally cooled to room temperature, washed, filtered and dried to obtain a MOFs material.

5. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 4, characterized in that: The usage ratio of the metal salt, the second ligand, the organic chromophore and the solvent is (0.08-0.2 mmol): (0.08-0.2 mmol): (0.04-0.1 mmol): (4-16 ml).

6. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 4, characterized in that: The solvent is any one of N,N-dimethylformamide, N,N-dimethylacetamide, acetonitrile, methanol and deionized water, or a mixture of several of them in any ratio.

7. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 4, characterized in that: The metal salt is one of zinc nitrate, zinc acetate, cadmium nitrate and cobalt chloride.

8. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 1, characterized in that: A combination of five MOFs materials was used to achieve adjustable luminescence from cyan to yellow to orange. The order of the combinations was Zn-IPA-TPPA, Zn-BPDC-TPPA, Zn-OBA-TPPA, Zn-BDC-TPPA, and Zn-FDA-TPPA.

9. The method for regulating the luminescence of triphenylamine metal-organic framework materials based on a mixed ligand strategy according to claim 8, characterized in that: The five MOFs materials are respectively prepared by using one of the five second ligands with tri(4-(pyridin-4-yl)phenyl)amine and zinc nitrate hexahydrate (Zn(NO3)2·6H2O); The five second ligands are isophthalic acid (H2IPA), biphenyl dicarboxylic acid (H2BPDC), 4,4'-diphenyl ether dicarboxylic acid (H2OBA), terephthalic acid (H2BDC) and 2,5-furan dicarboxylic acid (H2FDA).

10. A metal-organic framework material, characterized in that: It is prepared by using a metal salt, a second ligand and an organic chromophore, wherein the metal salt is zinc nitrate hexahydrate (Zn(NO3)2·6H2O); The second ligand is one of: 4,4'-diphenyl ether dicarboxylic acid (H2OBA), terephthalic acid (H2BDC), and 2,5-furan dicarboxylic acid (H2FDA); The organic chromophore is tris(4-(pyridin-4-yl)phenyl)amine (TPPA).

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