A safe and environmentally friendly blue long afterglow material
By doping hydroxybenzoic acid derivatives into cellulose, chitosan, or water-soluble polymers, low-toxicity blue long-afterglow materials are prepared, solving the pollution and solubility problems of existing materials and expanding their application in the fields of anti-counterfeiting and information encryption of water-soluble inks.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WUHAN TEXTILE UNIV
- Filing Date
- 2026-04-16
- Publication Date
- 2026-06-02
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to a long-afterglow phosphorescent material and its applications. This type of material belongs to the category of doped photoluminescent materials and can be used in fields such as anti-counterfeiting, information encryption, and time-resolved detection. Background Technology
[0002] Based on the resolution limit of the naked eye, long-persistence materials are generally defined as luminescent materials whose luminescence lifetime is greater than 0.1 s after the removal of radiation or excitation source at room temperature (refer to Chinese Patent CN202010641989X). Due to their great potential in encryption, bioimaging, and sensing, many materials with long-persistence luminescence have been developed. Traditional long-afterglow materials are mainly transition metal inorganic compounds. To reduce dependence on metal resources and avoid heavy metal pollution, many organic long-afterglow materials have been developed in recent years. The vast majority of these contain aromatic or heterocyclic rings (such as carbazole derivatives; see Carbazole isomers induce ultralong organic phosphorescence. Nat. Mater. 2021, 20, 175-180). In addition, some organic carbon nanodot materials also exhibit long-afterglow luminescence (see Crosslink-Enhanced Emission Effect on Luminescence in Polymers: Advances and Perspectives. Angew. Chem. Int. Ed. 2020, 59, 9826-9840). Most carbazole molecules and their derivatives have low polarity, requiring host-guest doping to enhance luminescence (see Structurally ResemblantDopants Enhance Organic Room-Temperature Phosphorescence, Advanced Materials 2022, 34). 2201569) These materials are not only hydrophobic, making it difficult to improve their solubility, but also cannot be used in biological environments without authorization due to their unclear toxicity. Furthermore, high doping concentrations also pose a risk of leakage, which limits the application scope of these materials.Most long-afterglow luminescent materials emit yellow-green afterglow, while efficient long-life blue afterglow materials are relatively rare (References: Long-lived organic room-temperature phosphorescence from amorphous polymer systems. Accounts of Chemical Research. 2022, 55(8): 1160-1170; Supramolecular purely organic room-temperature phosphorescence. Accounts of Chemical Research. 2021, 54(17): 3403-3414). This is because blue afterglow generally requires higher triplet energy (T1>2.7 eV), has rapid non-radiative decay, and is prone to quenching. Summary of the Invention
[0003] To achieve the purpose of this invention, hydroxybenzoic acid and its derivatives are used as luminescent units. Hydroxybenzoic acid and its derivatives (such as parabens) are rapidly metabolized in vivo, do not accumulate, and have extremely low acute toxicity (References: Safety assessment of esters of p-hydroxybenzoic acid (parabens). Food and chemical toxicology, 2005, 43(7): 985-1015; Matthews C, Davidson J, Bauer E, et al. p-Hydroxybenzoic acid esters as preservatives II.: Acute and chronic toxicity in dogs, rats, and mice. Journal of the American Pharmaceutical Association. 1956, 45(4): 260-267). Furthermore, these molecules contain only a single benzene ring, have a small conjugated system, and a large band gap. Experiments have shown that these small molecules, when doped into polymers at low concentrations, exhibit significant long-afterglow blue light emission.
[0004] This invention discloses a long afterglow material, characterized in that: the material is composed of luminescent small molecules doped in a matrix; the general structural formula of the luminescent small molecules is as follows: or or ; Among them, R1, R2, and R3 are independent and selected from hydrogen, alkyl, and alkyl containing hydroxyl substitution; The matrix is selected from cellulose, chitosan, or water-soluble or alcohol-soluble polymers, wherein the mass percentage of luminescent small molecules is between 0.01% and 20%.
[0005] Based on the above materials, this invention discloses a preferred long afterglow material, the preferred small molecule structure of which is as follows: or or or or or or or or or or or ; The matrix is selected from polyvinyl alcohol, hemicellulose or polyvinylpyrrolidone, wherein the mass percentage of luminescent small molecules is between 0.1% and 2%.
[0006] The aforementioned luminescent small molecules are all derived from commercially available sources or prepared using conventional organic synthesis techniques.
[0007] The preparation method of the above-mentioned long-afterglow materials is as follows: Select one or more of the above-mentioned molecules and dope them into a polymer matrix at a mass fraction of 0.01% to 20% to obtain long-afterglow materials with phosphorescence lifetimes of up to several seconds. After excitation with a 255-340 nm ultraviolet lamp, significant long-afterglow luminescence is visible to the naked eye. The phosphorescence of these materials is mainly between 400-600 nm, and the phosphorescence peak is mostly between 400-450 nm.
[0008] Based on the above materials, the solubility of luminescent small molecules in a polar matrix can be enhanced by introducing hydroxyl-containing alkyl groups, without significantly affecting the luminescence performance. Therefore, this invention discloses a preferred long afterglow material, wherein the structure of the luminescent small molecules used is as follows: or or ; These small molecules can be prepared using conventional organic synthesis techniques.
[0009] More preferably, the matrix is selected from polyvinyl alcohol, hemicellulose or polyvinylpyrrolidone, wherein the mass percentage of the luminescent small molecules is between 0.1% and 2%.
[0010] The long-afterglow luminescent material disclosed in this invention can be used in fields such as anti-counterfeiting, information encryption, and time-resolved detection. By dissolving or dispersing this material in a solvent, anti-counterfeiting ink can be obtained, which is suitable for hydrophilic substrates.
[0011] Compared with existing phosphorescent long afterglow materials, the phosphorescent material disclosed in this invention has the following advantages: Both the luminescent small molecules and the matrix exhibit low toxicity, making them suitable for use in food and pharmaceutical anti-counterfeiting applications. The luminescent small molecules have simple structures and are easy to synthesize. The single benzene ring structure of the luminescent unit has a large band gap and weak absorption of visible light, which does not affect the afterglow color of the prepared material. Furthermore, due to the high polarity of the small molecules and the matrix, they can be used in water-soluble or alcohol-soluble inks. Attached Figure Description
[0012] Figure 1 This is a luminescent image of a p-hydroxybenzoic acid film.
[0013] Figure 2 This is a luminescent image of a methylparaben film.
[0014] Figure 3 Image showing the luminescence of a p-methoxybenzoic acid thin film.
[0015] Figure 4 A luminescent image of a methyl phthalate film.
[0016] Figure 5 The phosphorescence spectrum of the p-hydroxybenzoic acid film.
[0017] Figure 6 The phosphorescence spectrum of methylparaben film.
[0018] Figure 7 The phosphorescence spectrum of the p-methoxybenzoic acid film.
[0019] Figure 8 The phosphorescence spectrum of the m-methoxybenzoic acid film.
[0020] Figure 9 Phosphorescence spectrum of methyl phthalate film.
[0021] Figure 10 Phosphorescence spectrum of o-methoxybenzoic acid film. Detailed Implementation
[0022] Example 1: Preparation of long afterglow materials and blue light afterglow Material preparation method: Take 0.01 g of p-hydroxybenzoic acid, p-methoxybenzoic acid, m-methoxybenzoic acid, methyl p-hydroxybenzoate, methyl o-hydroxybenzoate and o-methoxybenzoic acid (purchased from Anaiji Pharmaceutical Chemicals), and dissolve each in 10 g of 10% polyvinyl alcohol (purchased from Sinopharm Chemical Reagent Co., Ltd.) aqueous solution with a degree of polymerization of 1750±50. After ultrasonic mixing, remove moisture by natural drying or placing in a 60 ℃ forced-air drying oven to obtain a batch of polymer-doped thin film luminescent materials.
[0023] The structures of the individual small molecules are as follows: , , , , , .
[0024] The prepared films were placed in a dark room and excited with a 310 nm ultraviolet LED at room temperature. Images were taken with a Huawei Mate 10 smartphone. The specific method is described in the reference: Luminescence lifetime imaging of ultra-long roomtemperature phosphorescence on a smartphone. Analytical and Bioanalytical Chemistry. 2021, 413, 3291-3297. Imaging results for some of the films are attached. Figures 1 to 4 As shown, under ultraviolet light excitation, it emits blue light; after the ultraviolet light excitation stops, it has a long blue afterglow that lasts for several seconds.
[0025] The phosphorescence decay curves of each prepared thin film were measured using a Hitachi FL-4700 spectrometer with excitation at a wavelength of 310 nm. The phosphorescence lifetimes of each sample were obtained by multi-exponential fitting, as shown in the table below. The average phosphorescence lifetime of the prepared doped thin films was greater than 0.1 s, with the longest being close to 1 s.
[0026] Doped molecules Emission wavelength Average phosphorescence lifetime p-hydroxybenzoic acid 430 nm 0.75 s Methylparaben 440 nm 0.38 s p-Methoxybenzoic acid 420 nm 0.78 s m-Methoxybenzoic acid 450 nm 0.15 s methyl o-hydroxybenzoate 420 nm 0.94 s o-Methoxybenzoic acid 430 nm 0.30 s
[0027] The phosphorescence spectra of the corresponding thin films were measured using a Hitachi FL-4700 spectrometer with excitation wavelengths of 255 nm, 310 nm, and 365 nm. The results are attached. Figures 5 to 10 .
[0028] As demonstrated by the examples, regardless of the substitution positions of the hydroxyl or methoxy groups, these hydroxybenzoic acids and their derivatives all exhibit long-lasting blue phosphorescence in polyvinyl alcohol films, indicating that the electron-donating effect of the hydroxyl and methoxy groups and the electron-withdrawing effect of the carboxyl and ester bonds may be key factors in generating long-lasting phosphorescence. By extension, other structurally similar small molecules also possess similar properties. Compared to other small organic phosphorescent molecules, hydroxybenzoic acid and others are soluble in highly polar solvents such as water or ethanol and can be uniformly dispersed in polar matrices such as cellulose, chitosan, and starch. When p-hydroxybenzoic acid and methyl p-hydroxybenzoate are doped into the above matrices at a mass concentration of 1%, they both exhibit blue afterglow after excitation with 310 nm ultraviolet light.
Claims
1. A long afterglow material, characterized in that: This material is composed of luminescent small molecules doped into a matrix; the general structural formula of the luminescent small molecules is as follows: or or ; Among them, R1, R2, and R3 are independent and selected from hydrogen, alkyl, and alkyl containing hydroxyl substitution; The matrix is selected from cellulose, chitosan, or water-soluble or alcohol-soluble polymers, wherein the mass percentage of luminescent small molecules is between 0.01% and 20%.
2. The long afterglow material as described in claim 1, wherein the structure of the luminescent small molecule is as follows: or or or or or or or or or or or ; The matrix is selected from polyvinyl alcohol, hemicellulose or polyvinylpyrrolidone, wherein the mass percentage of luminescent small molecules is between 0.1% and 2%.
3. The long afterglow material as described in claim 1, wherein the structure of the luminescent small molecule is as follows: or or ; The matrix is selected from polyvinyl alcohol, hemicellulose or polyvinylpyrrolidone, wherein the mass percentage of luminescent small molecules is between 0.1% and 2%.