Use of a d-a type phenoxazine derivative in a mechanochromic material

Abstract

The application belongs to the technical field of force-induced color-changing materials, and provides application of a D-A type phenoxazine derivative in a force-induced color-changing material. In the application, the D-A type phenoxazine derivative is selected from any one of the following structural formulas:,, and. In the application, phenoxazine is used as an electron donor, and a differential control is performed on a terminal electron-accepting acceptor, so that precise control of single parent nucleus multiple light-emitting performance is realized, multifunctional phenoxazine derivative light-emitting molecules are obtained, multiple light-emitting performances such as AIE, thermally activated delayed fluorescence, and elastic crystal are considered, a multi-step synthesis process of skeleton modification is saved, rapid screening of materials in multiple scenes such as OLED and time-delay anti-counterfeiting is facilitated, the AIE characteristic is possessed, the fluorescence intensity is significantly enhanced when aggregation occurs with an increase in water content, excellent aggregation-induced emission performance is possessed, aggregation quenching of solid-state fluorescence is avoided, the ACQ quenching problem of a traditional conjugated pigment is solved, and the application is suitable for fields such as solid-state ink and solid-state fluorescence sensing.

Description

Technical Field

[0001] This invention relates to the field of mechanochromic materials technology, and more particularly to the application of a DA-type phenoxazine derivative in mechanochromic materials. Background Technology

[0002] Mechanofluorochromic organic solid-state materials, with their reversible fluorescence changes induced by external forces, possess immense application potential in areas such as intelligent stress sensors, dynamic anti-counterfeiting inks, and optical information storage, making them a current research hotspot in optoelectronic functional materials. Traditional conjugated fluorescent molecules are limited by the aggregation-induced quenching (ACQ) effect, resulting in significant fluorescence decay in the aggregated state, which fails to meet the practical requirements of solid-state devices. Following Academician Tang Benzhong's proposal of the aggregation-induced emission (AIE) theory, distorted non-planar luminescent molecules can suppress non-radiative transitions through intramolecular motion restriction (RIM), achieving efficient solid-state luminescence and greatly promoting the development of mechanochromic materials. Mechanochromic materials can undergo reversible changes in fluorescence wavelength and emission color under external stimuli such as friction, hydrostatic pressure, and tension. They possess irreplaceable application value in cutting-edge fields such as in-situ stress monitoring in aerospace, flaw detection of deep-sea pressure-bearing components, dynamic anti-counterfeiting of high-end documents, high-density optical information storage, and flexible OLEDs, and have been a key research direction in the interdisciplinary fields of optoelectronic functional materials, supramolecular crystal engineering, and polymer sensing for the past two decades.

[0003] Traditional organic conjugated fluorescent molecules generally suffer from the inherent defect of aggregation-induced fluorescence quenching (ACQ). That is, the molecules are highly fluorescent in dilute solutions, but when aggregated or crystallized into a solid state, the dense intermolecular π-π stacking causes the excited state to dissipate energy through nonradiative transitions, resulting in a significant decrease or even complete quenching of fluorescence in the solid state. This severely limits the application of traditional fluorescent dyes in solid-state devices and solid-state sensing scenarios. Academician Tang Benzhong proposed the scientific concept of aggregation-induced emission (AIE), which overturns people's inherent understanding of ACQ: AIE molecules with a twisted non-planar framework emit weak light in dilute solutions due to the consumption of excitation energy by intramolecular rotation or vibration. In the aggregated state, intramolecular motion is restricted, nonradiative transition channels are blocked, and radiative transitions dominate, thus significantly enhancing fluorescence. This lays the core theoretical foundation for the development of high-performance solid-state mechanochromic materials. Subsequently, researchers combined the AIE effect with DA (donor-acceptor) charge transfer structures to develop AIE-type mechanochromic molecules such as triphenylamine, tetraphenylethylene, and phenothiazine series. Among them, the phenothiazine series possesses a natural butterfly-shaped folded electron-rich heterocycle, with N and O heteroatoms providing abundant lone pairs of electrons, making it an excellent electron donor for constructing DA-type luminescent molecules. This twisted configuration molecule can be easily and precisely controlled in terms of molecular energy levels, stacking mode, and excited state type (transient fluorescence / thermally activated delayed fluorescence) by regulating the terminal electron-withdrawing acceptor. At the same time, phenothiazine derivatives generally possess crystallization-induced emission (CIE) properties, and the crystal stacking is easily reconstructed under external force, making it a preferred framework for developing high-performance mechanochromic materials.

[0004] Based on the current research status, the following technical problems of phenoxazine materials have not been systematically solved: (1) AIE mechanochromic materials have a single type of luminescence. At present, phenoxazine derivatives can only synthesize one of the following luminescent materials: traditional fluorescence, thermally activated delayed fluorescence, or phosphorescence. To obtain molecules with multiple luminescent properties, it is necessary to change the donor nucleus and carry out multiple chemical modifications. The synthesis route is complicated and the screening cost is high. It is impossible to obtain functional materials such as traditional fluorescence and thermally activated delayed fluorescence in batches as needed, which limits their flexible application in multiple scenarios such as OLED, time-delay anti-counterfeiting, and biological probes. (2) The material has a single color and insufficient reversibility of grinding color change. Color change recovery depends on fumigation solvent. Most mechanochromic crystals on the market are converted from crystalline to amorphous after grinding, and the fluorescence is red-shifted, but it cannot be restored on its own. It is necessary to use organic solvent vapor such as dichloromethane to fumigate in order to restore the original luminescence. It is impossible to achieve in-situ reversible use in closed devices and solid-state sensing systems.

[0005] Therefore, how to successfully apply phenoxazine derivatives to methemochromic materials and leverage their inherent luminescent properties is an urgent problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide an application of DA-type phenoxazine derivatives in mechanochromic materials, addressing the shortcomings of existing technologies.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an application of a DA-type phenoxazine derivative in mechanochromic materials, wherein the DA-type phenoxazine derivative is selected from any one of the following structural formulas: , , .

[0008] Preferably, the mechanochromic material is used in the fields of stress sensing, OLED display, data storage, or dynamic anti-counterfeiting.

[0009] Preferably, the DA-type phenoxazine derivative is prepared by a coupling reaction between phenoxazine and a brominated aryl acceptor.

[0010] Preferably, the structural formula of the phenoxazine is as follows: .

[0011] Preferably, the structural formula of the bromoaryl acceptor is as follows: , or .

[0012] The beneficial effects of this invention are: When subjected to external force, mechanochromic materials undergo a transformation between crystalline and amorphous states. Specifically, in the original crystalline state, molecules are arranged in a long-range ordered stack, forming a stable aggregate state. At this time, the molecular conformation is relatively fixed, and the intramolecular charge transfer excited state is at a characteristic energy level, corresponding to a specific emission wavelength and a high quantum yield of light emission. After being subjected to external force, the long-range ordered crystalline structure is disrupted, and the molecular stack changes from an ordered crystalline state to an amorphous and disordered state. The intermolecular interactions weaken, the molecular conformation becomes planarized to a certain extent, the effective conjugation length increases, and the energy level of the intramolecular charge transfer excited state decreases, ultimately leading to a redshift in the fluorescence emission wavelength and a visible color change. Through evaporation with organic solvents, the energy and driving force for molecular rearrangement are provided, and an ordered crystalline stack is formed again, thereby restoring the emission wavelength to the original crystalline state and realizing a reversible cycle of color-changing behavior.

[0013] This invention uses phenothiazine as an electron donor and differentiates the terminal electron-withdrawing acceptor to achieve precise control of multiple luminescent properties of a single parent nucleus, obtaining multifunctional phenothiazine derivative luminescent molecules that combine multiple luminescent properties such as AIE, thermally activated delayed fluorescence, and elastic crystals. It eliminates the need for a multi-step synthesis process involving skeleton modification, facilitating rapid screening of materials for various scenarios such as OLEDs and time-delayed anti-counterfeiting.

[0014] The DA-type phenoxazine derivative of this invention possesses AIE characteristics, and its fluorescence intensity is significantly enhanced when aggregation occurs with increased water content. It exhibits excellent aggregation-induced emission performance, avoids aggregation quenching of solid-state fluorescence, solves the ACQ quenching problem of traditional conjugated pigments, and is suitable for fields such as solid inks and solid-state fluorescence sensing. Attached Figure Description

[0015] Figure 1 The hydrogen NMR spectrum of POXCN; Figure 2 The image shows the carbon NMR spectrum of POXCN. Figure 3 The hydrogen NMR spectrum of POXO; Figure 4 The carbon NMR spectrum of POXO Figure 5 The 1H NMR spectrum of POXTZ; Figure 6 The carbon NMR spectrum of POXTZ; Figure 7 The solid-state fluorescence spectra and photographs of POXCN before grinding, after grinding, and after fumigation are shown. Figure 8 The solid-state fluorescence spectra and photographs of POXO before grinding, after grinding, and after fumigation are shown. Figure 9 The solid-state fluorescence spectra and photographs of POXTZ before grinding, after grinding, and after fumigation are shown. Figure 10 The fluorescence emission spectra of POXCN in tetrahydrofuran / water mixed solutions with different water volume fractions are shown. Figure 11 The graph shows the fluorescence intensity of POXCN in tetrahydrofuran / water mixed solutions with different water volume fractions as a function of water volume fraction. Figure 12 The fluorescence emission spectra of POXO in tetrahydrofuran / water mixed solutions with different water volume fractions are shown. Figure 13 The graph shows the fluorescence intensity of POXO in tetrahydrofuran / water mixed solutions with different water volume fractions as a function of water volume fraction. Figure 14 The fluorescence emission spectra of POXTZ in tetrahydrofuran / water mixed solutions with different water volume fractions are shown. Figure 15 The graph shows the fluorescence intensity of POXTZ in tetrahydrofuran / water mixed solutions with different water volume fractions as a function of water volume fraction. Figure 16 The fluorescence lifetime spectrum of POXCN; Figure 17The fluorescence lifetime spectrum of POXO; Figure 18 This is the fluorescence lifetime spectrum of POXTZ. Detailed Implementation

[0016] This invention provides an application of a DA-type phenoxazine derivative in mechanochromic materials, wherein the DA-type phenoxazine derivative is selected from any one of the following structural formulas: , , .

[0017] In this invention, the force-induced color-changing material is preferably used in the fields of stress sensing, OLED display, data storage, or dynamic anti-counterfeiting.

[0018] In this invention, the DA-type phenoxazine derivative is preferably prepared by a coupling reaction between phenoxazine and a brominated aryl acceptor.

[0019] In this invention, the preferred structural formula of the phenoxazine is... The twisted structure of phenoxazine is the fundamental structural basis for its responsive color change. It has an electron-rich heterocyclic structure with a butterfly-like folding shape. It is not a flat planar structure in space and has a high degree of twist. Its structure determines that the molecules cannot stick together very tightly during crystallization and will not form a strong π-π stack. The overall crystal packing is relatively loose. Under external force, the originally orderly crystal structure can be easily broken up and rearranged, changing from a regular crystalline state to a disordered amorphous state, which macroscopically manifests as a significant change in the luminescent color.

[0020] In this invention, the Marked as POXCN; The Labeled as POXO; The Marked as POXTZ.

[0021] In this invention, the preferred structural formula of the brominated aryl receptor is... , or DA-type phenoxazine derivatives possess a DA structure with an electron-donating phenoxazine terminal and an electron-withdrawing aryl terminal. This allows for spatial separation of the HOMO and LUMO orbitals, effectively reducing the energy level difference between singlet and triplet states. Based on the same parent nucleus, they can achieve three different luminescence properties: ordinary transient fluorescence, thermally activated delayed fluorescence, and room-temperature phosphorescence. A significant charge transfer effect exists within the molecule, which can alter the emission wavelength through external forces. The density and arrangement of molecular packing directly affect the energy level of the charge-transfer excited state. Specifically, in the crystalline state, the molecules are neatly arranged, resulting in strong intermolecular interactions, higher charge-transfer state energy levels, and shorter emission wavelengths. After grinding into an amorphous state, the molecular conformation becomes flatter, the effective conjugation length increases, the charge-transfer state energy level decreases, and the emission shifts towards longer wavelengths, a color change that can be visually observed. Using cyano, aldehyde, and triazine groups as electron-withdrawing terminals, the electron-withdrawing ability increases sequentially, and the corresponding intramolecular charge transfer effect also becomes stronger. This is reflected in the mechanochromic properties by showing that the stronger the electron-withdrawing acceptor, the greater the shift in the emission wavelength before and after grinding. By controlling the color change amplitude of the mechanochromic material through these three electron-withdrawing terminal acceptors, a gradient change in luminescence can be achieved.

[0022] In this invention, the specific operation of the coupling reaction preferably includes: mixing phenoxazine, bromoaryl acceptor, potassium carbonate, bis(tri-tert-butylphosphine)palladium and toluene to carry out the coupling reaction.

[0023] In this invention, the temperature of the coupling reaction is preferably 100~140℃, more preferably 110~130℃, and even more preferably 120℃; the time of the coupling reaction is preferably 8~16h, more preferably 10~14h, and even more preferably 12h.

[0024] In this invention, the molar ratio of the phenoxazine to the bromoaryl acceptor is preferably 4:2 to 4, more preferably 4:2.5 to 3.5, and even more preferably 4:3; The preferred ratio of phenoxazine, potassium carbonate, bis(tert-butylphosphine)palladium, and toluene is 4 mmol: 1-2 mmol: 0.05-0.2 mmol: 10-30 mL, more preferably 4 mmol: 1.2-1.8 mmol: 0.08-0.15 mmol: 15-25 mL, and even more preferably 4 mmol: 1.5 mmol: 0.1 mmol: 20 mL.

[0025] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0026] The preparation method and structural characterization of the DA-type phenoxazine derivative used in the embodiments of the present invention are as follows: To a Schlenk tube, 8 mmol of phenoxazine, 6 mmol of 4-bromobenzonitrile, 3 mmol of anhydrous potassium carbonate, and 0.2 mmol of bis(tri-tert-butylphosphine)palladium were added. After three nitrogen purgings, 30 mL of anhydrous and oxygen-free toluene was added using a syringe. The Schlenk tube was placed in a 120°C oil bath and refluxed under stirring for 12 h to carry out the coupling reaction. After the reaction was completed and cooled to room temperature, the reaction solution was extracted, dehydrated by adding anhydrous sodium sulfate, filtered, and then transferred to a round-bottom flask for rotary evaporation under reduced pressure to remove toluene, yielding the crude product. The crude product was purified by column chromatography (eluting with 300-400 mesh silica gel, with petroleum ether:dichloromethane = 3:1 as the developing solvent). The target fractions were collected by TLC monitoring, and the eluents were combined, evaporated to dryness, and then vacuum dried at 45°C to obtain the DA-type phenoxazine derivative, labeled POXCN.

[0027] POXCN was characterized by NMR. Figure 1 This is the 1H NMR spectrum of POXCN. Figure 2 The following are the carbon NMR spectra of POXCN: ¹H NMR (400 MHz, DMSO-d6) δ 8.13 (d, J = 8.1 Hz, 2H), 7.67 (d, J = 8.2 Hz, 2H), 6.79–6.67 (m, 6H), 5.92 (s, 2H). ¹³C NMR (101 MHz, chloroform-d) δ 144.09, 143.79, 134.99, 133.26, 123.37, 122.32, 118.12, 115.97, 113.41, 112.21.

[0028] To a Schlenk tube, 8 mmol of phenoxazine, 6 mmol of 4-bromobenzaldehyde, 3 mmol of anhydrous potassium carbonate, and 0.2 mmol of bis(tri-tert-butylphosphine)palladium were added. After three nitrogen purgings, 30 mL of anhydrous and oxygen-free toluene was added using a syringe. The Schlenk tube was placed in a 120°C oil bath and refluxed under stirring for 12 h to carry out the coupling reaction. After the reaction was completed and cooled to room temperature, the reaction solution was extracted, dehydrated by adding anhydrous sodium sulfate, filtered, and then transferred to a round-bottom flask for rotary evaporation under reduced pressure to remove toluene, yielding the crude product. The crude product was purified by column chromatography (eluting with 300-400 mesh silica gel, with petroleum ether:dichloromethane = 5:1 as the developing solvent). The target fractions were collected by TLC monitoring, and the eluents were combined, evaporated to dryness, and then vacuum dried at 45°C to obtain the DA-type phenoxazine derivative, labeled POXO.

[0029] POXO was characterized by NMR. Figure 3 This is the 1H NMR spectrum of POXO. Figure 4The following are the carbon NMR spectra of POXO: ¹H NMR (400 MHz, DMSO-d6) δ 10.11 (s, 1H), 8.19 (d, J = 8.3 Hz, 2H), 7.67 (d, J = 8.3 Hz, 2H), 6.81–6.66 (m, 6H), 5.94 (d, J = 1.7 Hz, 2H). ¹³C NMR (101 MHz, chloroform-d) δ 191.08, 144.99, 144.07, 135.88, 133.50, 132.34, 131.49, 123.33, 122.07, 115.84, 113.42.

[0030] Add 4 mmol of phenoxazine, 3 mmol of 2-(4-bromophenyl)-4,6-diphenyl-1,3,5-triazine, 2 mmol of anhydrous potassium carbonate, and 0.2 mmol of bis(tert-butylphosphine)palladium to a Schlenk tube. After three nitrogen purgings, add 30 mL of anhydrous and oxygen-free toluene using a syringe. Place the Schlenk tube in a 120°C oil bath and reflux with stirring for 12 h to carry out the coupling reaction. After the reaction is complete and cooled to room temperature, the reaction solution is extracted, dehydrated with anhydrous sodium sulfate, filtered, and then transferred to a round-bottom flask for rotary evaporation under reduced pressure to remove toluene, yielding the crude product. Purify the crude product using column chromatography (eluting with 300-400 mesh silica gel, developing solvent: petroleum ether:dichloromethane = 8:1). Collect the target fractions by TLC monitoring, combine the eluates, evaporate to dryness, and then vacuum dry at 45°C to obtain the DA-type phenoxazine derivative, labeled POXTZ.

[0031] POXTZ was characterized by NMR. Figure 5 The 1H NMR spectrum of POXTZ Figure 6 The following is the carbon NMR spectrum of POXTZ, with NMR data as follows: ¹H NMR (400 MHz, chloroform-d) δ 9.02 (d, J = 8.3 Hz, 2H), 8.86–8.80 (m, 4H), 7.69–7.58 (m, 8H), 6.78–6.61 (m, 6H), 6.07 (d, J = 7.7 Hz, 2H). ¹³C NMR (101 MHz, chloroform-d) δ 171.88, 170.91, 143.99, 142.93, 136.39, 136.04, 133.99, 132.75, 131.75, 131.10, 129.03, 128.75, 123.34, 121.64, 115.63, 113.35.

[0032] Example 1

[0033] POXCN was ground, and then the ground POXCN was fumigated with dichloromethane vapor. Solid-state fluorescence spectra and photographs of the original crystalline POXCN, the ground POXCN, and the fumigated POXCN were recorded using 365 nm as the excitation wavelength. Figure 7 The images show solid-state fluorescence spectra and photographs of POXCN before, after, and after fumigation.

[0034] Figure 7 The results showed that the original crystalline state before grinding was brown under sunlight and blue under 365nm ultraviolet light; the powder state after grinding was yellowish-white under sunlight and cyan under 365nm light, and the fluorescence spectrum after grinding showed a red shift; after fumigation, the fluorescence color and fluorescence spectrum both returned to the original crystalline state before grinding.

[0035] Example 2

[0036] POXO was ground and then fumigated with dichloromethane vapor. Solid-state fluorescence spectra and photographs of the original crystalline, ground, and fumigated POXO samples were recorded using 365 nm as the excitation wavelength. Figure 8 The images show solid-state fluorescence spectra and photographs of POXO before grinding, after grinding, and after fumigation.

[0037] Figure 8 The results showed that the original crystalline state before grinding was yellow-green under sunlight and yellow under 365nm ultraviolet light; the powder state after grinding was brown under sunlight and yellow-green under 365nm light, and the fluorescence spectrum after grinding showed a red shift; after fumigation, the fluorescence color and fluorescence spectrum both returned to the original crystalline state before grinding.

[0038] Example 3

[0039] POXTZ was ground and then fumigated with dichloromethane vapor. Solid-state fluorescence spectra and photographs of the original crystalline, ground, and fumigated POXTZ samples were recorded using 365 nm as the excitation wavelength. Figure 9 The images show the solid-state fluorescence spectra and photographs of POXTZ before, after, and after fumigation.

[0040] Figure 9 The results showed that the original crystalline state before grinding was yellow under sunlight and dark green under 365nm ultraviolet light; the powder state after grinding was yellow-green under sunlight and light green under 365nm light, and the fluorescence spectrum after grinding showed a red shift; after fumigation, the fluorescence color and fluorescence spectrum both returned to the original crystalline state before grinding.

[0041] AIE characterization of DA-type phenoxazine derivatives: Using THF as solvent, prepare 1×10 -5 A stock solution of POXCN at a concentration of 1 × 10⁻⁶ mol / mL was prepared. A 5 mL volume of the POXCN stock solution was transferred, and water was added to prepare a series of solutions with a concentration of 1 × 10⁻⁶ mol / mL. -5 A mol / mL POXCN solution was prepared, with water volume fractions of 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99% respectively. The solution was allowed to stand at room temperature for 30 min to allow water molecules to aggregate fully. The maximum emission wavelength and fluorescence intensity were recorded using 365 nm as the excitation wavelength and a scanning range of 400–700 nm. Figure 10 The fluorescence emission spectra of POXCN in tetrahydrofuran / water mixed solutions with different water volume fractions are shown. Figure 11 The graph shows the fluorescence intensity of POXCN in tetrahydrofuran / water mixed solutions with different water volume fractions as a function of water volume fraction. The results show that the fluorescence intensity of POXCN in the pure aqueous phase (99% water volume fraction) is significantly higher than that in the pure THF phase (0% water volume fraction). This result indicates that POXCN possesses aggregation-induced emission (AIE) characteristics.

[0042] Replace POXCN with POXO and POXTZ respectively, and repeat the AIE feature test steps. Figure 12 The fluorescence emission spectra of POXO in tetrahydrofuran / water mixed solutions with different water volume fractions are shown. Figure 13 The graph shows the fluorescence intensity of POXO in tetrahydrofuran / water mixed solutions with different water volume fractions as a function of water volume fraction. The results show that the fluorescence intensity of POXO in the pure aqueous phase (99% water volume fraction) is significantly higher than that in the pure THF phase (0% water volume fraction). This result indicates that POXO possesses aggregation-induced emission (AIE) characteristics.

[0043] Figure 14 The fluorescence emission spectra of POXTZ in tetrahydrofuran / water mixed solutions with different water volume fractions are shown. Figure 15 The graph shows the fluorescence intensity of POXTZ in tetrahydrofuran / water mixed solutions with different water volume fractions as a function of water volume fraction. The results show that the fluorescence intensity of POXTZ in the pure aqueous phase (99% water volume fraction) is significantly higher than that in the pure THF phase (0% water volume fraction). This result indicates that POXTZ possesses aggregation-induced emission (AIE) characteristics.

[0044] Figure 16 This is the fluorescence lifetime spectrum of POXCN. Figure 17 This is the fluorescence lifetime spectrum of POXO. Figure 18 This is the fluorescence lifetime spectrum of POXTZ.

[0045] As can be seen from the above embodiments, the present invention provides an application of DA-type phenoxazine derivatives in mechanochromic materials, wherein the DA-type phenoxazine derivatives are selected from any one of the following structural formulas: , , Using phenoxazine as an electron donor, differential modulation of the terminal electron-withdrawing acceptor enables precise control of multiple luminescent properties from a single parent nucleus. It can achieve three different luminescent characteristics: ordinary transient fluorescence, thermally activated delayed fluorescence, and room temperature phosphorescence. It possesses AIE characteristics, and its fluorescence intensity is significantly enhanced when aggregation occurs with increased water content. It exhibits excellent aggregation-induced emission performance, avoids aggregation quenching of solid-state fluorescence, and solves the ACQ quenching problem of traditional conjugated pigments. It is suitable for applications such as solid inks and solid-state fluorescence sensing.

[0046] The mesothermal material of this invention is prepared into a fluorescent coating and applied to the surfaces of aerospace components, deep-sea pressure equipment, and large mechanical parts. By observing the change in fluorescence color under ultraviolet light, stress concentration areas and micro-damage locations can be identified intuitively and quickly. The long-lifetime characteristic of phosphorescence can be effectively shielded from interference from ambient background fluorescence through time-resolved detection technology, significantly improving the signal-to-noise ratio and accuracy of the detection. This makes it suitable for non-destructive testing under complex conditions, representing the core application scenario for mesothermal materials. The mesothermal material can also be composited with flexible polymer substrates such as PDMS and hydrogels to prepare flexible stress-sensing films, which can be attached to the surfaces of human joints and skin. Changes in the emitted color can detect changes in human movement amplitude and muscle tension in real time. The phosphorescence property enables signal reading without continuous excitation light, reducing device power consumption. Methocytochromic materials, when formulated into anti-counterfeiting inks and printed on tickets, certificates, and high-end product packaging, offer triple anti-counterfeiting capabilities. Their multi-dimensional stimulus-response characteristics significantly increase the difficulty of counterfeiting, surpassing traditional single-fluorescent anti-counterfeiting materials. Furthermore, they enable dynamic anti-counterfeiting through a "write-erase" mode. Localized mechanical pressure causes a change in fluorescence to write information, while solvent vapor evaporation restores the initial state to erase the information, allowing for repeated reading and writing. Combined with the temporal characteristics of phosphorescence, a two-dimensional "space-time" information encoding system is constructed, enhancing the density and security of optical storage. Methocytochromic materials also possess TADF properties, making them suitable as solution-processable OLED emissive layer materials. Flexible OLED devices fabricated using these materials can dynamically control their emission color under bending, pressing, and other external forces. The reversibility of methocytochromism allows for the fabrication of passively driven optical filters and color-changing switches, eliminating the need for an external electric field.

[0047] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of a DA-type phenoxazine derivative in mechanochromic materials, characterized in that, The DA-type phenoxazine derivative is selected from any one of the following structural formulas: 、 、 。 2. The application according to claim 1, characterized in that, The aforementioned mechanochromic material is used in stress sensing, OLED display, data storage, or dynamic anti-counterfeiting applications.

3. The application according to claim 1 or 2, characterized in that, The DA-type phenoxazine derivative was prepared by a coupling reaction between phenoxazine and a brominated aryl acceptor.

4. The application according to claim 3, characterized in that, The structural formula of the phenoxazine is: .

5. The application according to claim 4, characterized in that, The structural formula of the bromoaryl acceptor is as follows: , or .

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