A long-life full-color cellulose room temperature phosphorescent material, its preparation method and application

Abstract

The present project discloses a long-lifetime full-color cellulose room-temperature phosphorescent material, its preparation method and applications. The method includes: mixing cellulose with sodium periodate and sodium borohydride to obtain hydroxycellulose through a redox reaction; secondly, reacting the hydroxycellulose with an aromatic ring derivative with a boronic acid group through a click reaction to obtain the long-lifetime full-color cellulose room-temperature phosphorescent material. This method features simple and rapid reactions, does not require any organic reagents, and for the first time realizes the long-lifetime phosphorescence of cellulose for 2.67 s. The prepared material has good water solubility and broad application prospects in the fields of information anti-counterfeiting, encryption, delayed lighting, afterglow display, etc., effectively improving the defects of natural room-temperature phosphorescent materials such as poor tunability of afterglow color and short lifetime, and providing new references for the high-value utilization of cellulose.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass room-temperature phosphorescent materials, and particularly relates to a long-lifetime full-color cellulose room-temperature phosphorescent material, a preparation method thereof, and an application thereof. Background Art

[0002] Due to the ability to eliminate the interference of background fluorescence and light scattering, room-temperature phosphorescent materials have broad application prospects in the fields of anti-counterfeiting, sensing, information encryption, optoelectronic devices, and bioimaging. However, traditional inorganic phosphorescent materials have harsh preparation conditions, high prices, scarce resources, and high toxicity, which limit their practical applications. Therefore, the development of pure organic room-temperature phosphorescent materials has become a new research hotspot. There are two key problems to be solved in the preparation of organic room-temperature phosphorescent materials. One is to strengthen spin-orbit coupling and promote the intersystem crossing process to promote the generation of triplet excitons. The other is to inhibit the quenching of triplet excitons and non-radiative transitions. Although some strategies such as metal coordination, H-aggregation, heavy-atom effect, and polymerization have achieved breakthroughs such as tunable afterglow color, long lifetime, and high phosphorescence quantum yield. However, the organic room-temperature phosphorescent materials synthesized based on the above strategies need to be in a crystalline state or doped in a rigid matrix, which requires fine processes and cumbersome procedures, and consumes a large amount of organic reagents, causing environmental pollution. Cellulose is rich in reserves, has a clear structure, low cost, and good biocompatibility in nature, and is an ideal research object for the preparation of green organic room-temperature phosphorescent materials. However, the high proportion of hydroxyl structures in cellulose leads to a single electron and cluster structure, severely restricting its phosphorescent properties. Therefore, the present invention proposes to prepare a long-lifetime full-color cellulose room-temperature phosphorescent material through a simple click chemical reaction, which has a certain leading edge. Summary of the Invention

[0003] In order to realize the application of biomass in the optoelectronic field, overcome the problems of single afterglow color, complex preparation process, and use of organic reagents existing in current organic room-temperature phosphorescent materials, as well as the pain points such as the application limitations of organic room-temperature phosphorescent materials, the primary object of the present invention is to provide a cellulose-based room-temperature phosphorescent material.

[0004] The object of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a preparation method of a long-lifetime full-color cellulose room-temperature phosphorescent material. The method includes converting cellulose into hydroxyl cellulose with higher reactivity by oxidative modification; subsequently, realizing B-O covalent bond cross-linking and the interaction of hydroxyl groups through click chemical reaction between hydroxyl cellulose and aromatic ring derivatives with boric acid groups, and finally successfully obtaining a long-lifetime full-color cellulose room-temperature phosphorescent material; as a cellulose source of biomass, it has the characteristics of wide source, green environmental protection, and easy chemical modification, and has great application advantages and broad prospects.

[0005] Another object of the present invention is to provide application fields of long - life full - color cellulose room - temperature phosphorescent materials, such as anti - counterfeiting, encryption, delayed lighting, and afterglow display fields.

[0006] The present invention has the following beneficial effects:

[0007] 1. Using the sodium periodate - sodium borohydride system to direct the conversion of secondary hydroxyl groups in the low - reactivity ring of cellulose into primary hydroxyl groups not only solves the problem of low reactivity when cellulose directly covalently bonds with conjugated luminophores, but also enriches the construction methods of cellulose room - temperature phosphorescent materials.

[0008] 2. By regulating the types and conjugation degrees of aryl ring derivatives with boric acid groups, the present invention realizes the transformation of afterglow colors from blue to green to red, which effectively increases the possibility of high - value utilization of biomass.

[0009] 3. Stabilize the triplet excitons of the system through the rigid environment of hydroxycellulose, and use aryl ring derivatives with boric acid groups to efficiently construct B - O covalent bonds through click reactions. The reaction process is simple and fast, can be completed in aqueous solution, does not consume organic reagents, and can be well used in fields such as anti - counterfeiting, encryption, delayed lighting, and afterglow display. It has a broad market prospect and provides a new direction for the high - value utilization of biomass. Description of the Drawings

[0010] Figure 1 Preparation flow chart of long - life full - color cellulose room - temperature phosphorescent materials

[0011] Figure 2 Fourier transform infrared spectra of cellulose, aldehyde - group cellulose, and hydroxycellulose in Example 1

[0012] Figure 3 Normalized steady - state photoluminescence and phosphorescence spectra of long - life full - color cellulose room - temperature phosphorescent materials in Example 3

[0013] Figure 4 Phosphorescence decay curve of long - life full - color cellulose room - temperature phosphorescent materials in Example 3 Detailed Embodiments

[0014] Example 1

[0015] Using microcrystalline cellulose as the raw material, oxidatively and reductively modifying cellulose with sodium periodate and sodium borohydride, and then obtaining highly reactive hydroxycellulose through dialysis treatment. The specific preparation steps of hydroxycellulose are as follows:

[0016] (1) Weigh accurately 31.68 g of microcrystalline cellulose and add it to 1000 mL of water. Then add 75.28 g of sodium periodate and react at 40 °C for 12 h. After the reaction, add 80 mL of ethylene glycol to terminate the reaction. Subsequently, dialyze for 7 days. After dialysis, freeze-dry to obtain the oxidized product aldehyde cellulose. It has the following structure:

[0017]

[0018] (2) Weigh accurately 3 g of the oxidized product aldehyde cellulose and dissolve it in 100 mL of water. Add 1.2 g of sodium borohydride and react at room temperature for 4 h. After the reaction, add glacial acetic acid dropwise to make the pH of the solution reach neutral. Subsequently, dialyze for 7 days. After dialysis, freeze-dry to obtain the reduced product hydroxycellulose. It has the following structure:

[0019]

[0020] Example 2

[0021] Using microcrystalline cellulose as the raw material, cellulose is oxidized and reduced modified by sodium periodate and sodium borohydride, and then dialyzed to obtain hydroxycellulose with high reactivity. The specific preparation steps of hydroxycellulose are as follows:

[0022] (3) Weigh accurately 31.68 g of microcrystalline cellulose and add it to 1000 mL of water. Then add 75.28 g of sodium periodate and react at 60 °C for 6 h. After the reaction, add 80 mL of ethylene glycol to terminate the reaction. Subsequently, dialyze for 7 days. After dialysis, freeze-dry to obtain the oxidized product aldehyde cellulose. It has the following structure:

[0023]

[0024] (4) Weigh accurately 3 g of the oxidized product aldehyde cellulose and dissolve it in 100 mL of water. Add 0.3 g of sodium borohydride and react at room temperature for 4 h. After the reaction, add glacial acetic acid dropwise to make the pH of the solution reach neutral. Subsequently, dialyze for 7 days. After dialysis, freeze-dry to obtain the reduced product hydroxycellulose. It has the following structure:

[0025]

[0026] Example 3

[0027] Using the reduced product hydroxycellulose as the raw material, click chemical reaction is carried out with arylboronic acid to obtain long-lived full-color phosphorescent cellulose. The specific preparation steps of phosphorescent cellulose are as follows:

[0028] Accurately weigh 100 mg of the reduced product hydroxycellulose and add it to 0.6 mL of water. Weigh 1 mg of tetraphenylethylene boronic acid and add it to 0.8 mL of water. Mix the above solutions and add 0.2 mL of ammonia water. React at 80 °C for 20 min. After the reaction, freeze-dry to obtain long-lived full-color phosphorescent cellulose.

[0029] Example 4

[0030] Using the reduced product hydroxycellulose as a raw material, click chemical reaction is carried out with arylboronic acid to obtain long-lived full-color phosphorescent cellulose. The specific preparation steps of the phosphorescent cellulose are as follows:

[0031] Accurately weigh 100 mg of the reduced product hydroxycellulose and add it to 0.6 mL of water. Weigh 50 mg of phenanthrene-9-boronic acid and add it to 0.8 mL of water. Mix the above solutions and add 0.2 mL of ammonia water. React at 80 °C for 1 min. After the reaction, freeze-dry to obtain long-lived full-color phosphorescent cellulose.

Claims

1. A preparation method of a long - life full - color cellulose room - temperature phosphorescent material, characterized in that, It includes the following steps: 1) Weigh microcrystalline cellulose and sodium periodate in a molar ratio of 0.5 - 2 mol : 1 - 2 mol, add them to distilled water, react for 6 - 24 h under the condition of a temperature of 40 - 70 °C. After the reaction ends, add ethylene glycol to terminate the reaction, dialyze to remove impurities and perform freeze-drying to obtain aldehyde cellulose; 2) Dissolve the aldehyde cellulose obtained in step 1) in distilled water, add sodium borohydride at a mass ratio of aldehyde cellulose to sodium borohydride of 1:0.1 g - 1:1 g at room temperature, react for 1 - 4 h. After the reaction ends, adjust the pH to neutral with glacial acetic acid, dialyze to remove impurities and perform freeze-drying to obtain hydroxycellulose; 3) Take the hydroxycellulose obtained in step 2) and dissolve it in distilled water. Add one or more aryl ring derivatives with boric acid groups selected from carbazole derivatives, fluorene derivatives, benzene derivatives, tetraphenylethylene derivatives, naphthalene derivatives, biphenyl derivatives, phenanthrene derivatives, anthracene derivatives and pyrene derivatives according to a mass ratio of hydroxycellulose to aryl ring derivatives with boric acid groups of 1:1 - 1:10000. Then add ammonia water as a catalyst, place it at 30 - 80 °C and react for 0.2 - 1 h. After the reaction ends, perform freeze-drying to obtain a long-life full-color cellulose phosphorescent material.

2. The preparation method of a long - lifespan all - color cellulose room - temperature phosphorescent material according to claim 1, characterized in that, In step 1), the dosage of the ethylene glycol is 40 - 80 mL.

3. Application of the long-life full-color cellulose room-temperature phosphorescent material obtained by the preparation method described in claim 1 in the fields of information anti-counterfeiting, encryption, delayed lighting and afterglow display.

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