Biodegradable full-color ultra-long room-temperature phosphorescent material

Abstract

The invention discloses a biodegradable full-color ultra-long room-temperature phosphorescent material, and belongs to the field of preparation of pure organic long-afterglow materials. The material is prepared by doping small organic molecules containing methylamine hydrochloride into gamma-polyglutamic acid (gamma-PGA), and has the advantages that the raw materials are cheap, the preparation method is simple, and the obtained material has the advantages of ultra-long luminous life, high quantum efficiency, capability of being excited by visible light, full-color luminescence, biodegradability and the like; the method can be applied to the fields of long afterglow pattern display, advanced anti-counterfeiting encryption and the like, and has huge commercial potential.

Description

Technical Field

[0001] This invention belongs to the field of preparation of pure organic long-afterglow materials, specifically involving a biodegradable full-color ultra-long room-temperature phosphorescent material. This type of material can be applied in fields such as long-afterglow pattern display and advanced anti-counterfeiting encryption. Background Technology

[0002] Organic long-afterglow materials have attracted widespread attention due to their long excited-state lifetime, low cost, and good processability, and have broad application prospects in fields such as anti-counterfeiting and information encryption, afterglow display, bio-imaging, and sensing. Currently, there are two main strategies for synthesizing high-efficiency organic phosphorescent materials: (1) promoting the transition of singlet excitons from the lowest singlet excited state (S1) to the triplet excited state (T). n (2) Limiting the nonradiative decay of excitons. Typically, spin-orbit coupling is promoted by introducing heavy atoms, heteroatoms and carbonyl groups, thereby promoting intersystem crossing processes; nonradiative transitions of triplet excitons are suppressed by crystallization engineering, polymerization and host-guest doping.

[0003] Stimulus-responsive materials are smart materials whose luminescence can be modulated by applying external stimuli (e.g., light, force, and temperature). Some progress has been made in stimulus-responsive long-persistence materials; for example, force-induced long-persistence can be achieved by changing the phosphorescence color through grinding, and temperature or solvents can quench phosphorescence, enhance photoluminescence lifetime, and increase luminescence intensity. However, stimulus-responsive long-persistence materials are mainly small-molecule organic crystal materials, whose preparation processes are complex and their processing performance is poor, greatly limiting their practical applications. Among existing organic long-persistence materials, polymer-based organic phosphorescence systems are particularly popular due to their good processability, flexibility, and reproducibility. However, polyvinyl polymers are not completely degradable, and recycling is difficult. Therefore, developing stimulus-responsive, biodegradable long-persistence material systems remains a significant challenge. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a biodegradable full-color ultra-long room-temperature phosphorescent material, which has advantages such as ultra-long luminescence lifetime, high quantum efficiency, ability to be excited by visible light, full-color luminescence, and biodegradability.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A biodegradable, full-color, ultra-long-lasting room-temperature phosphorescent material is prepared by incorporating small organic molecules containing methylamine hydrochloride as guest molecules into γ-polyglutamic acid (γ-PGA) as the host.

[0006] Furthermore, the material is prepared by mixing organic small molecules containing methylamine hydrochloride with γ-polyglutamic acid, dissolving them in deionized water, stirring at 50°C for 1 h, and then drying.

[0007] Furthermore, the organic small molecule containing methylamine hydrochloride is selected from any one of the following formulas: .

[0008] Furthermore, the mass ratio of the organic small molecule containing methylamine hydrochloride to γ-polyglutamic acid used is 1:200.

[0009] Furthermore, the material can be excited by visible light to produce long afterglow, and by changing the guest molecules, full-color phosphorescence from deep blue to red can be achieved. In addition, after being irradiated by ultraviolet lamp for a period of time, its phosphorescence emission color will change and its luminescence lifetime will be enhanced. The room temperature phosphorescence lifetime after irradiation can be as long as 2548 ms, and the phosphorescence quantum efficiency is as high as 20%. Therefore, it can be applied to long afterglow displays, information anti-counterfeiting, etc.

[0010] γ-Polyglutamic acid (γ-PGA) possesses numerous amino, carboxyl, and amide groups, providing a rigid hydrogen-bonded environment. Meanwhile, small organic molecules containing methylamine hydrochloride exhibit good solubility and can provide ionic bonds, enhancing the interaction with γ-polyglutamic acid (γ-PGA). Therefore, doping small organic molecules into γ-polyglutamic acid (γ-PGA) effectively suppresses non-radiative transitions of these molecules, thereby promoting long-afterglow organic luminescence. Furthermore, γ-polyglutamic acid (γ-PGA) offers advantages such as non-toxicity, biodegradability, and low cost. Thus, the organic long-afterglow material prepared using γ-polyglutamic acid (γ-PGA) as the main material in this invention possesses important properties such as visible light excitation, tunable emission color, and biodegradability, which is beneficial for meeting the application requirements of room-temperature phosphorescent materials in long-afterglow pattern display, anti-counterfeiting encryption, and biodegradability.

[0011] The beneficial effects of this invention are as follows: (1) This invention uses organic small molecules containing methylamine hydrochloride as guests and γ-polyglutamic acid (γ-PGA) as the host molecule. Through physical doping, visible light-excited, biodegradable full-color organic long afterglow material can be easily prepared.

[0012] (2) The preparation method of the present invention is simple to operate, low in cost and low in toxicity. The resulting material has great potential in the fields of long afterglow pattern display, advanced anti-counterfeiting and biodegradation. Attached Figure Description

[0013] Figure 1 The phosphorescence spectrum and lifetime decay curve of γ-polyglutamic acid (γ-PGA) are shown.

[0014] Figure 2 The phosphorescence spectra of the pure organic long afterglow materials prepared in Examples 1-4 are shown.

[0015] Figure 3 The phosphorescence spectra of the pure organic long afterglow materials prepared in Examples 3 and 4 after irradiation with 365 nm ultraviolet light are shown.

[0016] Figure 4 The graphs show the luminescence of the pure organic long-afterglow materials prepared in Examples 1-4 under ultraviolet light irradiation at a certain wavelength and after the light is turned off, along with the corresponding lifetime decay curves.

[0017] Figure 5 The images show the luminescence of the pure organic long-afterglow materials prepared in Examples 3-4 after being irradiated with ultraviolet light of a certain wavelength, and the corresponding lifetime decay curves.

[0018] Figure 6 The images show the phosphorescence excitation spectrum and the photoluminescence spectrum of the pure organic long afterglow material prepared in Example 3, as well as the photoluminescence spectrum of the material under LED illumination and after it is turned off.

[0019] Figure 7 The image shows a comparison of digits written using the aqueous solution of the pure organic long afterglow material prepared in Examples 2 and 4 as ink before and after irradiation with 275 and 365 nm ultraviolet light.

[0020] Figure 8 The image shows a comparison of the effects of applying an aqueous solution of the pure organic long afterglow material prepared in Example 2 as an anti-counterfeiting coating to the digital amount of RMB banknotes before and after irradiation with 275 nm ultraviolet light.

[0021] Figure 9 A comparison of the degradation of γ-polyglutamic acid (γ-PGA) film and polylactic acid (PLA) film in soil. Detailed Implementation

[0022] A biodegradable full-color ultra-long room temperature phosphorescent material is prepared by adding organic small molecules containing methylamine hydrochloride and γ-polyglutamic acid (γ-PGA) together in deionized water at a mass ratio of 1:200, stirring at 50°C for 1 h, and then drying at 50°C for 12 h to form a film.

[0023] The organic small molecule containing methylamine hydrochloride is selected from any one of the following formulas: .

[0024] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0025] Unless otherwise specified, all raw materials and reagents used in this invention can be purchased from the market or prepared by existing methods.

[0026] Example 1 1 mg of p-guanidinobenzonitrile hydrochloride (CGH) and 200 mg of γ-polyglutamic acid (γ-PGA) were weighed into 20 mL glass bottles, 2 mL of deionized water was added, the mixture was heated to 50 °C and stirred for 1 h. After the solution was completely clear, it was transferred to a 50 °C oven and dried for 12 h to form a film, thus obtaining 0.5 wt.% pure organic long afterglow material CGH@γ-PGA.

[0027] Example 2 1 mg of 1-naphthylamine hydrochloride (NAH) and 200 mg of γ-polyglutamic acid (γ-PGA) were weighed into 20 mL glass bottles, 2 mL of deionized water was added, the mixture was heated to 50 °C and stirred for 1 h. After the solution was completely clear, it was transferred to a 50 °C oven and dried for 12 h to form a film, thus obtaining 0.5 wt.% pure organic long afterglow material NAH@γ-PGA.

[0028] Example 3 1 mg of 9-aminoacridine hydrochloride (AAH) and 200 mg of γ-polyglutamic acid (γ-PGA) were weighed into 20 mL glass bottles, 2 mL of deionized water was added, the mixture was heated to 50 °C and stirred for 1 h. After the solution was completely clear, it was transferred to a 50 °C oven and dried for 12 h to form a film, thus obtaining 0.5 wt.% pure organic long afterglow material AAH@γ-PGA.

[0029] Example 4 1 mg of 1-pyrene methylamine hydrochloride (PYH) and 200 mg of γ-polyglutamic acid (γ-PGA) were weighed into 20 mL glass bottles, 2 mL of deionized water was added, the mixture was heated to 50 °C and stirred for 1 h. After the solution was completely clear, it was transferred to a 50 °C oven and dried for 12 h to form a film, thus obtaining 0.5 wt.% pure organic long afterglow material PYH@γ-PGA.

[0030] Figure 1 The figure shows the phosphorescence spectrum and lifetime decay curve of γ-polyglutamic acid (γ-PGA). As can be seen from the figure, the bio-based polymer γ-polyglutamic acid exhibits ultralong room temperature phosphorescence. The room temperature phosphorescence emission peak corresponding to 275 nm excitation is 452 nm, which can emit a blue afterglow, and the room temperature phosphorescence lifetime reaches 755 ms.

[0031] Figure 2The figures show the phosphorescence spectra of the pure organic long-afterglow materials prepared in Examples 1-4 before UV illumination. As can be seen from the figures, the phosphorescence spectral peaks of the pure organic long-afterglow materials prepared in Examples 1-4 are located at 429 nm, 515 nm, 560 nm and 609 nm, respectively. It can be seen that by introducing different organic small molecules containing methylamine hydrochloride into γ-polyglutamic acid, room temperature phosphorescence full-color luminescence from blue to red can be achieved.

[0032] Figure 3 The figures show the phosphorescence spectra of the pure organic long-afterglow materials prepared in Examples 3 and 4 after irradiation under a 365 nm UV lamp for 40 min. As can be seen from the figures, the phosphorescence peaks at 560 nm and 609 nm of the pure organic long-afterglow materials prepared in Examples 3 and 4 are blue-shifted to 474 nm and 517 nm, respectively. That is, the pure organic long-afterglow material prepared in Example 3 changes from a yellow afterglow to a blue afterglow, and the pure organic long-afterglow material prepared in Example 4 changes from a red afterglow to a green afterglow.

[0033] Figure 4 The figures show the luminescence and lifetime decay curves of the pure organic long-afterglow materials prepared in Examples 1 and 2 under 275 nm UV light irradiation and after the UV light is turned off, and the luminescence and lifetime decay curves of the pure organic long-afterglow materials prepared in Examples 3 and 4 under 365 nm UV light irradiation and after the UV light is turned off. As can be seen from the figures, the pure organic long-afterglow materials prepared in Examples 1-4 emit blue or cyan fluorescence under UV light irradiation. After the UV light is turned off, a multicolored organic long-afterglow phenomenon of blue, green, yellow, and red can be observed. Simultaneously, by monitoring the lifetime of their phosphorescence emission peaks and plotting the corresponding lifetime decay curves, the room-temperature phosphorescence luminescence lifetimes were found to be 1332 ms, 1410 ms, 804 ms, and 305 ms, respectively.

[0034] Figure 5 The figures show the luminescence of the pure organic long-afterglow materials prepared in Examples 3 and 4 after irradiation with a 365 nm UV lamp for 40 min, and the corresponding lifetime decay curves. As can be seen from the figures, the pure organic long-afterglow materials prepared in Examples 3 and 4 emit blue fluorescence under UV light irradiation. After the UV lamp is turned off, blue and green organic long-afterglow can be observed respectively, and their room-temperature phosphorescence lifetimes are significantly improved, reaching 2548 ms and 2307 ms respectively.

[0035] The phosphorescence excitation spectrum of the pure organic long afterglow material prepared in Example 3 and the excitation spectrum of the LED were tested at room temperature. The results are shown in [Figure 1]. Figure 6 .Depend on Figure 6 As can be seen, the phosphorescence excitation spectrum of the pure organic long afterglow material prepared in Example 3 overlaps significantly with the excitation spectrum of the LED. The photograph further proves that the pure organic long afterglow material prepared in Example 3 can be excited by the LED lamp and produce a 7-second yellow afterglow.

[0036] Application Example 1 According to Examples 2 and 4, a solution of 1 mg NAH or PYH, 200 mg γ-polyglutamic acid, and 2 mL deionized water was used as ink to write different numbers on A4 paper (wherein, the number "1" was written in Example 2 and the number "2" was written in Example 4), and then dried at 50°C for 2 h.

[0037] Figure 7 The images show a comparison of the luminescence of different written numbers under 275 nm and 365 nm UV light illumination, and after the UV light is turned off. As can be seen from the images, under 275 nm UV light illumination, only a strong blue fluorescent background is observed. After the UV light is turned off, the number combination "1212" can be observed with a green afterglow. When the UV light is turned off for 7 seconds, the number combination "11" can be observed. Under 365 nm UV light illumination, only a strong blue fluorescent background is also observed. After the UV light is turned off, the number combination "1212" can be observed, and the number "2" exhibits a red afterglow. When the UV light is turned off for 1 second, the number combination "22" can be observed, and the number "2" also exhibits a red afterglow. This demonstrates that the obtained material can emit multicolored afterglow, making it suitable for advanced encryption.

[0038] Application Example 2 According to Example 2, a solution of 1 mg NAH, 200 mg γ-polyglutamic acid, and 2 mL deionized water was used as an anti-counterfeiting coating and applied to the digital amount of RMB banknotes, and then dried at 50°C for 2 h.

[0039] Figure 8 This image shows a comparison of the luminescence of the numeral "10" on a RMB banknote after the anti-counterfeiting coating has been applied, under 275 nm ultraviolet light and with the light off. As can be seen in the image, a green afterglow can be observed in the numeral "10" after the ultraviolet light is turned off.

[0040] Application Example 3 Using biodegradable polylactic acid (PLA) films as a reference, the degradation behavior of γ-polyglutamic acid (γ-PGA) films in soil at 20℃ and 20% relative humidity was investigated.

[0041] Figure 9 The figures show the biodegradation of γ-polyglutamic acid (γ-PGA) and polylactic acid (PLA) films in soil. As can be seen from the figures, the γ-PGA film gradually became covered with mycelia and became invisible within 7 days (left), while the PLA film remained essentially unchanged (right), demonstrating the excellent biodegradability of γ-PGA.

[0042] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A biodegradable, full-color, ultra-long-lasting room-temperature phosphorescent material, characterized in that, The material is prepared by doping small organic molecules containing methylamine hydrochloride into γ-polyglutamic acid.

2. The biodegradable full-color ultra-long room-temperature phosphorescent material according to claim 1, characterized in that, The specific preparation method involves mixing organic small molecules containing methylamine hydrochloride with γ-polyglutamic acid, dissolving them in deionized water, stirring at 50°C for 1 h, and then drying the mixture.

3. A biodegradable full-color ultra-long room-temperature phosphorescent material according to claim 1 or 2, characterized in that, The organic small molecule containing methylamine hydrochloride is selected from any one of the following formulas: 。 4. A biodegradable full-color ultra-long room-temperature phosphorescent material according to claim 1 or 2, characterized in that, The mass ratio of the organic small molecules containing methylamine hydrochloride to γ-polyglutamic acid used was 1:

200.

5. A biodegradable full-color ultra-long room-temperature phosphorescent material according to claim 1 or 2, characterized in that, The material is capable of achieving full-color phosphorescence from deep blue to red, and its room-temperature phosphorescence lifetime is greater than 2 s.

6. An application of the full-color ultra-long room temperature phosphorescent material as described in claim 1 in long afterglow display or information anti-counterfeiting.

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