Rare earth europium metal complex stress luminescent material as well as preparation method and application thereof

Abstract

The invention discloses a rare earth europium metal complex stress luminescent material as well as a preparation method and application thereof, and belongs to the technical field of stress luminescent materials. The chemical formula of the rare earth europium metal complex stress luminescent material is Eu (tpfd) 3L, tpfd is 4-pyridine formyl trifluoroacetone, and L is 2, 2 '-dipyridyl or 1, 10-phenanthroline. The Eu (tpfd) 3L is prepared by a solvent evaporation method. The material has very strong stress luminescence performance and photoluminescence performance, and has very good acid-base stability. The material not only can generate bright red light through stimulation of mechanical force so as to realize visual conversion of force-light, but also can be widely applied to various fields such as visual pressure sensing, intelligent anti-counterfeiting, electronic signature, flexible wearable sensing equipment or biomedical treatment and the like. Moreover, the preparation method disclosed by the invention is simple to operate, low in equipment requirement, small in reaction energy consumption, high in sample yield and good in reproducibility.

Description

Technical Field

[0001] The present invention relates to the technical field of stress luminescent materials, and in particular to a rare earth europium metal complex stress luminescent material and a preparation method and application thereof. Background Art

[0002] Stress luminescent (ML) materials are materials that emit light when subjected to stress stimulation. The modes of action of stress stimulation include but are not limited to extrusion, grinding, friction, impact, ultrasound and other forms, involving the conversion of mechanical energy into visible light. In recent years, a variety of inorganic and organic stress luminescent compounds have been successfully prepared and have shown great application prospects in the fields of real-time stress sensors, signature graphics, displays, structural damage monitoring, wearable lighting devices, self-powered displays, mechanical energy collection and conversion, and bio-imaging equipment.

[0003] The stress luminescent materials reported so far include three categories: organic, inorganic, and organic-inorganic hybrid materials. Among them, the synthesis process of organic stress luminescent materials is complicated and tedious, the luminescent wavelength is broad, unstable, and the structure is easy to collapse; inorganic stress luminescent materials have a single material type, mainly sulfur-based systems and inorganic oxide systems, poor biocompatibility, low luminescent intensity, and easy quenching after moisture absorption, which increases the environmental restrictions in practical applications. In addition, the existing stress luminescent materials also have the following problems: (1) The structural problems of the stress luminescent powder itself lead to its poor luminescent performance. There are few stress luminescent materials that show strong luminescent brightness at room temperature; (2) The preparation conditions of inorganic stress luminescent materials are usually more stringent, requiring anhydrous and oxygen-free conditions and the reaction temperature is usually hundreds or even thousands of degrees Celsius. The long reaction time, high reaction energy consumption, high equipment requirements, and high cost limit the large-scale production of such materials.

[0004] In summary, there are still relatively few types of materials with high stress luminescence intensity, so it is very necessary to develop, design and synthesize new high-intensity stress luminescence materials. Summary of the invention

[0005] The purpose of the present invention is to provide a rare earth europium metal complex stress luminescent material and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is a rare earth europium metal complex stress luminescent material, the chemical formula of which is Eu(tpfd)3L, wherein tpfd is 4-pyridinecarbonyltrifluoroacetone, and L is 2,2'-bipyridine or 1,10-phenanthroline.

[0008] In the rare earth europium metal complex, 4-pyridinecarbonyltrifluoroacetone is used as the main ligand, and 2,2'-bipyridine or 1,10-phenanthroline is used as the auxiliary ligand.

[0009] Furthermore, the Eu in the Eu(tpfd)3L has a valence of +3.

[0010] Furthermore, the stress luminescence is specifically mechanical stress luminescence, and the rare earth europium metal complex stress luminescence material generates bright red light through mechanical force stimulation, thereby realizing a visual transformation of force-light.

[0011] Furthermore, the rare earth europium metal complex stress luminescent material has both stress luminescent properties and photoluminescent properties.

[0012] The second technical solution of the present invention: The preparation method of the above-mentioned rare earth europium metal complex stress luminescent material uses 2,2'-bipyridine or 1,10-phenanthroline, 4-pyridinecarbonyltrifluoroacetone and europium salt as raw materials, and prepares the rare earth europium metal complex stress luminescent material by solvent volatilization method.

[0013] Furthermore, the solvent volatilization method specifically comprises the following steps:

[0014] 2,2'-bipyridine or 1,10-phenanthroline, a solvent and a europium salt are mixed for a first stirring reaction, and then 4-pyridinecarbonyltrifluoroacetone is added for a second stirring reaction. After the reaction is completed, the mixture is filtered and allowed to stand to obtain the rare earth europium metal complex stress luminescent material.

[0015] The target product can only be obtained by performing the reactions in the above-mentioned reaction sequence. Changing the reaction sequence, such as adding the primary ligand and the auxiliary ligand together (i.e., performing a stirring reaction once), or first adding the primary ligand (i.e., mixing the primary ligand with the solvent and the europium salt) for the first stirring reaction and then adding the auxiliary ligand for the second stirring reaction, will not result in the target product.

[0016] Furthermore, the europium salt is europium chloride, specifically EuCl3·6H2O; and the solvent is a mixed solution of triethylamine and anhydrous ethanol.

[0017] Furthermore, the volume ratio of triethylamine to anhydrous ethanol is 8:50000.

[0018] Furthermore, the first stirring reaction is carried out at room temperature, and the reaction time is 24-72 hours; the second stirring reaction is carried out at room temperature, and the reaction time is 2-10 hours.

[0019] Furthermore, the room temperature specifically refers to 20-30°C.

[0020] Furthermore, in terms of molar ratio, 2,2′-bipyridine or 1,10-phenanthroline: europium salt: 4-picolinyltrifluoroacetone=2:1:3.

[0021] Furthermore, the usage ratio of the 2,2'-bipyridine or 1,10-phenanthroline to the solvent is 0.2 mmol:25 mL.

[0022] Furthermore, the specific operation of mixing 2,2'-bipyridine or 1,10-phenanthroline, a solvent and a europium salt is: adding 2,2'-bipyridine or 1,10-phenanthroline to the solvent, stirring at room temperature for 10-30 minutes and then adding the europium salt.

[0023] Furthermore, the time for standing at room temperature is two weeks (14 days), and the purpose of standing at room temperature is to slowly volatilize the solvent.

[0024] The third technical solution of the present invention: Application of the above-mentioned rare earth europium metal complex stress luminescent material in visual pressure sensing, intelligent anti-counterfeiting, electronic signature, flexible wearable sensing equipment or biomedical fields.

[0025] Furthermore, the application method is: compounding the rare earth europium metal complex stress luminescent material with an organic polymer material to prepare a transparent composite film; attaching the composite film to the surface of the component to be tested, applying mechanical external force, and converting the stress of the component to be tested into light emission under the action of the mechanical external force. Through this process, high-brightness stress-light direct energy conversion can be achieved, visualization of pressure sensing can be achieved, and applications in the fields of intelligent anti-counterfeiting, electronic signature, flexible wearable sensing equipment or biomedicine can be realized.

[0026] Furthermore, the organic polymer material includes polyethylene terephthalate (PET) or polydimethylsiloxane (PDMS).

[0027] The present invention discloses the following technical effects:

[0028] (1) The rare earth europium metal complex stress luminescent material of the present invention uses 4-pyridine carboxylic acid trifluoroacetone as the main ligand and 2,2'-bipyridine or 1,10-phenanthroline as the auxiliary ligand. 4-pyridine carboxylic acid trifluoroacetone and the auxiliary ligand effectively sensitize the central Eu (III) ion to emit light through the "antenna effect", so that the material can emit strong narrow-band red light emission only under stress without illumination, and the stress luminescence peak is located near 617nm. The material has excellent stress luminescence performance, not only can strong red luminescence be observed under dark conditions, but also has bright red luminescence visible to the naked eye under bright natural light.

[0029] (2) Compared with the traditional high-temperature solid-phase preparation method of stress luminescent materials, the preparation method of rare earth europium metal complex stress luminescent materials disclosed in the present invention has simple process, mild and easy-to-control conditions, low equipment requirements, low reaction energy consumption, green and friendly to the environment and no pollution, and has high material yield, stable properties (with good acid-base stability), good reproducibility, good crystallinity, high purity, and is easy to industrialize.

[0030] (3) The stress luminescence material of the present invention has a stress luminescence intensity that is proportional to the magnitude of the applied mechanical force within a certain range, which can realize visualization of pressure sensing and can be applied to various intelligent sensing fields, such as visualized pressure sensing, intelligent anti-counterfeiting, electronic signatures, flexible wearable sensing devices, or biomedicine. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A three-dimensional stacking diagram of the crystal structure of the rare earth europium metal complex stress luminescent material prepared in Example 1, in which gray represents C atoms, red represents O atoms, dark blue represents N atoms, green represents F atoms, and sky blue represents Eu atoms;

[0033] Figure 2 A three-dimensional stacking diagram of the crystal structure of the rare earth europium metal complex stress luminescent material prepared in Example 2, in which gray represents C atoms, red represents O atoms, dark blue represents N atoms, green represents F atoms, and sky blue represents Eu atoms;

[0034] Figure 3 The X-ray powder diffraction pattern (PXRD) of the rare earth europium metal complex stress luminescent material prepared in Example 1 and the theoretical X-ray powder diffraction pattern of the material;

[0035] Figure 4 The X-ray powder diffraction pattern (PXRD) of the rare earth europium metal complex stress luminescent material prepared in Example 2 and the theoretical X-ray powder diffraction pattern of the material;

[0036] Figure 5 This is a photoluminescence excitation-emission spectrum of the rare earth europium metal complex stress luminescent material prepared in Example 1;

[0037] Figure 6This is a stress luminescence photograph of the rare earth europium metal complex stress luminescence material prepared in Example 1 under mechanical force in dark conditions;

[0038] Figure 7 This is a stress luminescence photograph of the rare earth europium metal complex stress luminescence material prepared in Example 1 under bright light and mechanical force;

[0039] Figure 8 X-ray powder diffraction patterns (PXRD) of the rare earth europium metal complex stress luminescent material prepared in Example 1 after being immersed in different pH conditions for 72 hours;

[0040] Fig. 9 The stress luminescence spectrum of the rare earth europium metal complex stress luminescence material prepared in Example 1 under different mechanical forces;

[0041] Fig.10 It is a linear fitting diagram of the luminescence intensity of the rare earth europium metal complex stress luminescent material prepared in Example 1 under different mechanical forces;

[0042] Fig.11 The stress luminescence spectrum of the rare earth europium metal complex stress luminescence material prepared in Example 2 under different mechanical forces;

[0043] Fig.12 This is a handwritten luminescent image of a stress luminescent signature anti-counterfeiting film made of a PET film wrapped with a rare earth europium metal complex stress luminescent material in Application Example 2;

[0044] Fig.13 These are photos of the samples prepared in Comparative Examples 1 and 2 under stress. DETAILED DESCRIPTION

[0045] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0046] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0047] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0048] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0049] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0050] The 4-pyridinecarbonyl trifluoroacetone (structural formula: ) is prepared as follows: 3 g (0.056 mol) of sodium methoxide is added to 30 mL of anhydrous ether, 7.2 mL (0.06 mol) of ethyl trifluoroacetate diluted with 30 mL of anhydrous ether is added under stirring, and then 6.6 mL (0.06 mol) of 4-acetylpyridine diluted with 30 mL of anhydrous ether is added dropwise, and the mixed system is refluxed at 45° C. for 5 hours; after the reaction is completed, water is added to dissolve the obtained solid, and multiple extractions are performed with anhydrous ether; the aqueous phase is acidified with dilute hydrochloric acid (concentration of 10 wt%) to precipitate a yellow solid powder, which is recrystallized with ethanol-water (volume ratio of 1:10) to obtain yellow transparent 4-pyridinecarbonyltrifluoroacetone crystals.

[0051] The 2,2'-bipyridine (structural formula: )、1,10-phenanthroline (structural formula is ) and other raw materials are common commercially available products.

[0052] The room temperature involved in the following examples and comparative examples specifically refers to 20-30°C.

[0053] Example 1

[0054] 2,2'-Bipyridine (0.312 g, 0.2 mmol) was added to a mixed solvent consisting of 0.004 mL triethylamine and 25 mL anhydrous ethanol, and stirred at room temperature for 30 minutes. Then, EuCl3·6H2O (0.0366 g, 0.1 mmol) was added. After stirring at room temperature for 48 hours, 4-pyridinecarbonyltrifluoroacetone (0.0656 g, 0.3 mmol) was added. The mixed system was stirred in a semi-closed beaker at room temperature for 4 hours and then filtered. The mixture was sealed and allowed to stand for slow evaporation of the solvent. After two weeks, the Eu(tpfd)3L sample was obtained (its crystal structure three-dimensional stacking diagram is shown in FIG. Figure 1 The sample purity was 99% and the yield was 54%.

[0055] Example 2

[0056] 1,10-Phenanthroline (0.396 g, 0.2 mmol) was added to a mixed solvent consisting of 0.004 mL triethylamine and 25 mL anhydrous ethanol, and stirred at room temperature for 30 minutes. Then, EuCl3·6H2O (0.0366 g, 0.1 mmol) was added. After stirring at room temperature for 48 hours, 4-pyridinecarbonyltrifluoroacetone (0.0656 g, 0.3 mmol) was added. The mixed system was stirred in a semi-closed beaker at room temperature for 4 hours and then filtered. The mixture was sealed and allowed to stand for slow evaporation of the solvent. After two weeks, the Eu(tpfd)3L sample was obtained (its crystal structure three-dimensional stacking diagram is shown in FIG. Figure 2 The sample purity was 99% and the yield was 52%.

[0057] Comparative Example 1

[0058] The same as Example 1, except that 2,2'-bipyridine is replaced by an equal molar amount of 4,4'-bipyridine.

[0059] Comparative Example 2

[0060] Same as Example 1, except that 4-pyridinecarbonyl trifluoroacetone is replaced by an equimolar amount of benzoyl trifluoroacetone (structural formula: ).

[0061] Application Example 1

[0062] 10 g of polydimethylsiloxane and 10 g of Eu(tpfd)3L obtained in Example 1 were fully mixed to obtain a mixture, and then the mixture was transferred to a 3×3 cm square mold and dried in an oven at 80° C. for 5 hours to achieve curing and degassing to obtain a transparent composite film.

[0063] Application Example 2

[0064] 5 g of Eu(tpfd)3L prepared in Example 1 was transferred to a 3×3 cm square mold. Subsequently, Eu(tpfd)3L was wrapped with a PET film and the wrapped film was thermoformed using a laminator to obtain a transparent composite film as a stress luminescent signature anti-counterfeiting film.

[0065] Test Case

[0066] Figure 3 The X-ray powder diffraction pattern (PXRD) of the rare earth europium metal complex stress luminescent material prepared in Example 1 and the theoretical X-ray powder diffraction pattern of the material prove the successful synthesis of the rare earth europium metal complex stress luminescent material. It can also be seen that all the diffraction peaks of the material prepared in Example 1 are consistent with the simulated crystal data, indicating that the material has a high purity.

[0067] Figure 4 The X-ray powder diffraction pattern (PXRD) of the rare earth europium metal complex stress luminescent material prepared in Example 2 and the theoretical X-ray powder diffraction pattern of the material prove the successful synthesis of the rare earth europium metal complex stress luminescent material. It can also be seen that all the diffraction peaks of the material prepared in Example 2 are consistent with the simulated crystal data, indicating that the material has a high purity.

[0068] Figure 5 The photoluminescence excitation-emission spectrum of the rare earth europium metal complex stress luminescent material prepared in Example 1 shows that the excitation spectrum of the material prepared in Example 1 covers the ultraviolet region and extends to the visible light region. 3+ ion 5 D0→ 7 F j characteristic transition peak.

[0069] Figure 6 This is a stress luminescence photograph of the rare earth europium metal complex stress luminescent material prepared in Example 1 under mechanical force (only mechanical force is applied without light excitation) under dark conditions. It can be seen that the material generates bright red light under the stimulation of mechanical force.

[0070] Figure 7 This is a stress luminescence photograph of the rare earth europium metal complex stress luminescent material prepared in Example 1 under bright light and mechanical force (only mechanical force is applied, no light excitation is performed). It can be seen that the material produces bright red light visible to the naked eye under bright natural light under the stimulation of mechanical force.

[0071] Figure 8The X-ray powder diffraction pattern (PXRD) of the rare earth europium metal complex stress luminescent material prepared in Example 1 after being immersed in different pH conditions at room temperature for 72 hours. It can be seen that the diffraction peaks of the material remain consistent after being immersed in different pH solutions, indicating that the material has good acid and alkali stability.

[0072] Fig. 9 The stress luminescence spectrum of the rare earth europium metal complex stress luminescence material prepared in Example 1 under different mechanical forces shows that the stress luminescence peak of the material is located near 617nm, and the stress luminescence intensity of the material increases with the increase of the mechanical force.

[0073] Fig.10 This is a linear fitting diagram of the luminescence intensity of the rare earth europium metal complex stress luminescent material prepared in Example 1 under different mechanical forces. It can be seen that within a certain range, the stress luminescence intensity of the material has a good linear relationship with the magnitude of the applied mechanical force, and the correlation coefficient R 2 =0.99673.

[0074] Fig.11 The stress luminescence spectrum of the rare earth europium metal complex stress luminescence material prepared in Example 2 under different mechanical forces shows that the stress luminescence peak of the material is located near 617nm, and the stress luminescence intensity of the material increases with the increase of the mechanical force.

[0075] Fig.12 This is the handwritten luminescence image of the stress luminescent signature anti-counterfeiting film made of PET film wrapped with rare earth europium metal complex stress luminescent material in Application Example 2. It can be seen that after handwriting the signature on the anti-counterfeiting film, a strong red luminescence phenomenon can be observed under dark conditions.

[0076] Fig.13 These are photos of the samples prepared in Comparative Examples 1 and 2 under stress. It can be seen that the samples prepared in Comparative Examples 1 and 2 have no stress luminescence phenomenon.

[0077] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A rare earth europium metal complex stress luminescent material, characterized in that: The chemical formula is Eu(tpfd)3L, wherein tpfd is 4-pyridinecarbonyltrifluoroacetone, and L is 2,2'-bipyridine or 1,10-phenanthroline.

2. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 1, characterized in that: The rare earth europium metal complex stress luminescent material is prepared by using 2,2'-bipyridine or 1,10-phenanthroline, 4-pyridinecarbonyl trifluoroacetone and europium salt as raw materials through a solvent volatilization method.

3. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 2, characterized in that: The solvent volatilization method specifically comprises the following steps: 2,2'-bipyridine or 1,10-phenanthroline, a solvent and a europium salt are mixed for a first stirring reaction, and then 4-pyridinecarbonyltrifluoroacetone is added for a second stirring reaction. After the reaction is completed, the mixture is filtered and allowed to stand at room temperature to obtain the rare earth europium metal complex stress luminescent material.

4. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 3, characterized in that: The europium salt is europium chloride; and the solvent is a mixed solution of triethylamine and anhydrous ethanol.

5. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 4, characterized in that: The volume ratio of the triethylamine to anhydrous ethanol is 8:50000.

6. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 3, characterized in that: The first stirring reaction is carried out at room temperature for 24-72 hours; the second stirring reaction is carried out at room temperature for 2-10 hours.

7. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 3, characterized in that: In terms of molar ratio, 2,2'-bipyridine or 1,10-phenanthroline: europium salt: 4-picolinyltrifluoroacetone = 2:1:

3.

8. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 3, characterized in that: The usage ratio of the 2,2'-bipyridine or 1,10-phenanthroline to the solvent is 0.2 mmol:25 mL.

9. The method for preparing the rare earth europium metal complex stress luminescent material according to claim 3, characterized in that: The room temperature standing time is two weeks.

10. Application of the rare earth europium metal complex stress luminescent material as claimed in claim 1 in visual pressure sensing, intelligent anti-counterfeiting, electronic signature, flexible wearable sensing equipment or biomedical field.

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