Humidity-pH stimuli-responsive room temperature phosphorescent paper as well as preparation raw materials, preparation method and application thereof
By physically blending nitrogen-substituted 4-bromo-1,8 naphthalene dicarboxylic anhydride with plant cellulose, humidity-pH stimulation response room temperature phosphorescent paper was prepared, which solved the problem that existing materials were difficult to achieve two-factor response, and achieved widespread application in the fields of biomedicine and food.
Patent Information
- Application Number
- CN202510254350.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-05
- Publication Date
- 2025-06-06
AI Technical Summary
Existing organic room temperature phosphorescent materials are difficult to achieve two-factor or multi-factor response, limiting their application scope.
Humidity-pH stimulation-responsive room temperature phosphorescent paper was prepared by physically blending nitrogen-substituted 4-bromo-1,8 naphthalene dicarboxylic anhydride with plant cellulose as a polymer matrix.
The two-factor response of humidity and pH is achieved, enhancing the application potential of room temperature phosphorescent materials, especially in the biomedicine and food fields.
Smart Images
Figure CN120099817A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of functional materials, and in particular to a humidity-pH stimulus responsive room temperature phosphorescent paper, a preparation raw material thereof, a preparation method thereof and an application thereof. Background Art
[0002] Organic Room-Temperature Phosphorescent Materials (ORTP) are a class of organic materials that can emit phosphorescence at room temperature. Phosphorescence is the light emitted when excited molecules return to the ground state through radiation transition. Unlike fluorescence, phosphorescence has a longer lifetime, usually in milliseconds to seconds. Organic room-temperature phosphorescent materials have the advantages of low cost, wide variety, good biocompatibility and processability.
[0003] However, due to the small spin-orbit coupling of pure organic materials, it is difficult for excitons to reach the triplet state through the intergap jumping process, which makes it difficult for most pure organic compounds to produce effective phosphorescence emission. At the same time, the radiative transition from the triplet excited state to the ground state is a forbidden process, which makes the radiative transition rate of phosphorescence small and easily affected by factors such as molecular collisions, vibrations or rotations, resulting in non-radiative inactivation. These factors limit the application of organic room temperature phosphorescent materials in dual-factor or multi-factor responses. Therefore, current organic room temperature phosphorescent materials can usually only achieve single-factor response.
[0004] In view of this, the present invention is proposed. Summary of the invention
[0005] The object of the present invention is to provide a humidity-pH stimulus responsive room temperature phosphorescent paper and its preparation raw materials and preparation method and application, so as to solve or improve the above technical problems.
[0006] The present invention can be implemented like this:
[0007] In a first aspect, the present invention provides a method for preparing raw materials for humidity-pH stimulus responsive room temperature phosphorescent paper, comprising the following steps: mixing nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride with a polymer matrix.
[0008] In an optional embodiment, the preparation of the humidity-pH stimulus responsive room temperature phosphorescent paper preparation raw material includes at least one of the following features:
[0009] Feature 1: The polymer matrix includes plant cellulose; preferably, the plant cellulose includes at least one of wood pulp, bamboo pulp and cotton pulp; more preferably, the plant cellulose is micronized fiber cellulose;
[0010] Feature 2: The mass ratio of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride to the polymer matrix is 0.5:100 to 2:100;
[0011] Feature 3: The mixing of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix is a physical blending method.
[0012] In an optional embodiment, the physical blending of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix comprises: forming a solution of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride, adding the solution to an aqueous dispersion of the polymer matrix and stirring and mixing.
[0013] In an optional embodiment, the stirring and mixing time is 0.5h to 8h.
[0014] In an optional embodiment, the stirring and mixing temperature is 10°C to 60°C.
[0015] In an alternative embodiment, the solvent in the solution of nitrogen-substituted 4-bromo-1,8-naphthoic anhydride is dimethyl sulfoxide.
[0016] In an alternative embodiment, the solid content of the aqueous dispersion of the polymer matrix is 0.1 wt% to 0.5 wt%.
[0017] In an optional embodiment, the preparation of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride comprises the following steps: subjecting 4-bromo-1,8-naphthalene dicarboxylic anhydride and an amine-based small molecule to an alcohol reflux reaction.
[0018] In an alternative embodiment, the preparation of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride includes at least one of the following features:
[0019] Feature 4: The amine-based small molecule includes a diamine compound; preferably, the diamine compound includes at least one of ethylenediamine and butanediamine;
[0020] Feature 5: The molar ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride to the amino small molecule is 1:2.5 to 1:4;
[0021] Feature 6: The reaction time of 4-bromo-1,8-naphthalene dicarboxylic anhydride and amino small molecules is 4h to 5h.
[0022] In an optional embodiment, the method further comprises: centrifuging and washing the mixture of 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix.
[0023] In an optional embodiment, the centrifugal washing is carried out at 5000 r / min to 8000 r / min.
[0024] In an optional embodiment, the number of centrifugal washing is 1 to 2 times.
[0025] In a second aspect, the present invention provides a raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper, which is prepared by the preparation method of any one of the aforementioned embodiments.
[0026] In a third aspect, the present invention provides a method for preparing humidity-pH stimulus responsive room temperature phosphorescent paper, comprising the following steps: forming a water dispersion from the raw materials for preparing the humidity-pH stimulus responsive room temperature phosphorescent paper of the aforementioned embodiment, then sheeting it into paper, and drying it.
[0027] In an optional embodiment, the drying temperature is 60°C to 80°C.
[0028] In an optional embodiment, the drying time is 6 hours to 8 hours.
[0029] In a fourth aspect, the present invention provides a humidity-pH stimulus responsive room temperature phosphorescent paper prepared by the preparation method of the aforementioned embodiment.
[0030] In an optional embodiment, the basis weight of the humidity-pH stimulus responsive room temperature phosphorescent paper is 50 g / m 2 ~80g / m 2 .
[0031] In a fifth aspect, the present invention provides an application of the humidity-pH stimulus responsive room temperature phosphorescent paper as described in the aforementioned embodiment, and the humidity-pH stimulus responsive room temperature phosphorescent paper is used in the biomedical field and / or the food field.
[0032] In an optional embodiment, the humidity-pH stimulus responsive room temperature phosphorescent paper is used to detect or monitor the freshness of food.
[0033] In an optional embodiment, the humidity-pH stimulus-responsive room temperature phosphorescent paper is used for detecting or monitoring humidity in a biomedical environment or a food environment.
[0034] The beneficial effects of the present invention include:
[0035] The present invention uses synthetically prepared nitrogen-substituted 4-bromo-1,8-naphthalenedicarboxylic anhydride as a room temperature phosphorescent small molecule and combines it with a polymer matrix by physical blending to prepare humidity-pH stimulus-responsive room temperature phosphorescent paper. The preparation method is simple and easy to operate, and the reaction conditions are mild. The humidity-pH stimulus-responsive room temperature phosphorescent paper prepared by the method has humidity stimulus response and pH stimulus response characteristics, and can be applied to the fields of biomedicine and food. BRIEF DESCRIPTION OF THE DRAWINGS
[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.
[0037] Figure 1 This is the NMR spectrum of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 of the present invention;
[0038] Figure 2 This is the infrared spectrum of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 of the present invention;
[0039] Figure 3 This is a fluorescence spectrum of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 of the present invention;
[0040] Figure 4 The infrared spectra of cellulose before and after being combined with room temperature phosphorescent small molecules provided in Example 1 of the present invention;
[0041] Figure 5 Optical pictures of room temperature phosphorescent paper according to Example 1 of the present invention changing with humidity;
[0042] Figure 6 The fluorescence spectrum of the room temperature phosphorescent paper provided in Example 1 of the present invention as it changes with humidity;
[0043] Figure 7 The fluorescence lifetime diagram of the room temperature phosphorescent paper at 435 nm provided in Example 1 of the present invention;
[0044] Figure 8 The phosphorescence lifetime diagram of the room temperature phosphorescent paper at 565 nm provided in Example 1 of the present invention;
[0045] Fig. 9 The fluorescence spectrum of the room temperature phosphorescent paper provided in Example 1 of the present invention as the pH changes;
[0046] Fig.10 The fitting picture of the room temperature phosphorescent paper provided in Example 1 of the present invention as the pH changes;
[0047] Fig.11 Optical images of room temperature phosphorescent paper provided in Example 1 of the present invention changing with pH. DETAILED DESCRIPTION
[0048] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.
[0049] The humidity-pH stimulus responsive room temperature phosphorescent paper provided by the present invention, its preparation raw materials, its preparation method and application are described in detail below.
[0050] The present invention provides a method for preparing raw materials for humidity-pH stimulus responsive room temperature phosphorescent paper, comprising the following steps: mixing nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride (abbreviated as "BrNpE") with a polymer matrix.
[0051] Among them, polymer materials can provide a crystal-like rigid environment through strong hydrogen bonding ability or mutually entangled molecular chains, effectively reducing the non-radiative transition of phosphorescent chromophores and promoting the generation of room temperature phosphorescence.
[0052] In some optional embodiments, the polymer matrix includes plant cellulose, for example, may include at least one of wood pulp, bamboo pulp and cotton pulp. Exemplarily, the plant cellulose may be micronized fiber cellulose (MFC).
[0053] As a natural biomass-based polymer, the plant cellulose has the advantages of good biodegradability and biocompatibility, excellent mechanical properties and easy processing performance. The molecular structure of plant cellulose contains a six-membered pyran ring structure, which makes internal rotation difficult, and hydrogen bonds can be formed both within and between molecules. In particular, intramolecular hydrogen bonds prevent glycosidic bonds from rotating, thereby greatly increasing its rigidity, which can effectively limit the movement of phosphorescent small molecules, reduce energy dissipation, and inhibit non-radiative transitions. Therefore, plant cellulose can be used as a natural polymer matrix to provide a rigid polymer microenvironment and a rich hydrogen bond network, effectively improve the intersystem crossing efficiency of room temperature phosphorescent chromophores, inhibit the rapid non-radiative decay and oxygen quenching of the molecular excited triplet state, and achieve effective activation of room temperature phosphorescence.
[0054] In some optional embodiments, the mass ratio of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride to the polymer matrix can be 0.5:100 to 2:100, such as 0.5:100, 1:100, 1.5:100 or 2:100, or any other value within the range of 0.5:100 to 2:100.
[0055] Since the room temperature phosphorescent small molecule (nitrogen substituted 4-bromo-1,8 naphthalene dicarboxylic anhydride) and the polymer matrix are combined by a simple blending method, the room temperature phosphorescent small molecule is combined with the polymer matrix through hydrogen bonding forces, so the mass ratio of the room temperature phosphorescent small molecule to the polymer matrix is particularly important for the room temperature phosphorescence intensity and fluorescence intensity. If the ratio is too low, the luminescence intensity will be weak; if the ratio is too high, the luminescence intensity will be weakened due to aggregation fluorescence quenching.
[0056] In some optional embodiments, the nitrogen-substituted 4-bromo-1,8-naphthalic anhydride is mixed with the polymer matrix in a physical blending manner.
[0057] For example, the physical blending of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix may include: forming a solution of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride, and then adding the solution into an aqueous dispersion of the polymer matrix for stirring and mixing.
[0058] The solvent in the solution of nitrogen-substituted 4-bromo-1,8-naphthoic anhydride may be dimethyl sulfoxide.
[0059] The solid content of the aqueous dispersion of the polymer matrix may be 0.1 wt% to 0.5 wt%, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt% or 0.5 wt%, etc., or other values within the range of 0.1 wt% to 0.5 wt%.
[0060] The mass ratio of dimethyl sulfoxide to water in the aqueous dispersion may be 1:9, for example but not by way of limitation.
[0061] The stirring and mixing time can be 0.5h to 8h, such as 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 5h, 6h, 7h or 8h, etc., or other values within the range of 0.5h to 8h. In some preferred embodiments, the stirring and mixing time is 4h to 8h.
[0062] By stirring and mixing for the above time, the nitrogen-substituted 4-bromo-1,8-naphthoic anhydride and the polymer matrix can be fully combined, and the nitrogen-substituted 4-bromo-1,8-naphthoic anhydride can be more bonded to the surface of the polymer matrix.
[0063] In an optional embodiment, the stirring and mixing temperature is 10°C to 60°C, such as 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C, etc., and can also be other values within the range of 10°C to 60°C.
[0064] In the present invention, the preparation of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride may include the following steps: subjecting 4-bromo-1,8-naphthalene dicarboxylic anhydride (abbreviated as "BrNpA") and an amine-based small molecule to an alcohol reflux reaction.
[0065] Wherein, the amine-based small molecule may include a diamine compound. In some optional embodiments, the amine-based small molecule may include at least one of ethylenediamine and butanediamine.
[0066] The molar ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride to the amino small molecule can be 1:2.5 to 1:4, such as 1:2.5, 1:3, 1:3.5 or 1:4, or other values within the range of 1:2.5 to 1:4.
[0067] The reaction time of 4-bromo-1,8-naphthalene dicarboxylic anhydride and the amino small molecule can be 4 h to 5 h, such as 4 h, 4.5 h or 5 h, or other values within the range of 4 h to 5 h.
[0068] Furthermore, the mixture of 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix is centrifugally washed to remove the room temperature phosphorescent small molecules that have not reacted completely, thereby obtaining a phosphorescent small molecule combined with cellulose product (i.e., a raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper).
[0069] Among them, centrifugal washing can be carried out under the conditions of 5000r / min~8000r / min (such as 5000r / min, 5500r / min, 6000r / min, 6500r / min, 7000r / min, 7500r / min or 8000r / min, etc.).
[0070] The number of centrifugal washings can be illustratively but not limitedly 1 to 3 times, or more times according to actual needs.
[0071] Correspondingly, the present invention also provides a raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper, which is prepared by the above-mentioned preparation method.
[0072] The room temperature phosphorescent small molecule (nitrogen substituted 4-bromo-1,8 naphthalene dicarboxylic anhydride) provided by the present invention adopts 4-bromo-1,8 naphthalene dicarboxylic anhydride as a precursor. Considering that its own fluorescence intensity is relatively weak, the electron-donating group amino group is first modified at the 4-position of the naphthalene ring to form a strong electron-donating-withdrawing system to generate strong fluorescence. Then, the room temperature phosphorescent small molecule is introduced into the polymer by a simple blending method using a polymer long chain of a polymer matrix (such as lignocellulose fiber). Since the polymer matrix can provide a large number of hydrogen bonds, it is beneficial to fix the room temperature phosphorescent small molecule, and a certain isolation effect can be achieved, and the non-radiative transition of the room temperature phosphorescent small molecule can be suppressed, thereby helping to realize the excitation of the room temperature phosphorescence of a composite material based on a polymer matrix (i.e., a raw material for preparing humidity-pH stimulus-responsive room temperature phosphorescent paper), and realizing strong room temperature phosphorescence. In addition, since water molecules can easily destroy the hydrogen bonds between the polymer matrix and the room temperature phosphorescent small molecule, the breaking of the hydrogen bonds and the vibration of the water molecules can destroy the stability of the triplet excitons, thereby reducing the phosphorescence intensity. Therefore, the weak non-covalent hydrogen bond between the polymer matrix and the room temperature phosphorescent small molecule can be used as a reaction site to reversibly regulate the luminescence properties to construct a reversible humidity-responsive room temperature phosphorescent paper. In addition, the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride molecule has a pH response characteristic. After the polymer matrix and the room temperature phosphorescent small molecule are combined by weak hydrogen bonds, the fluorescence-pH response characteristics of the room temperature phosphorescent small molecule itself are still maintained. When the paper is in an acidic or alkaline environment, the water molecules destroy the weak hydrogen bonds between the polymer matrix and the room temperature phosphorescent small molecule, so the fluorescence-pH response characteristics of the phosphorescent small molecule itself are presented. Based on this, humidity-pH stimulus-responsive room temperature phosphorescent paper was successfully prepared through molecular confined excited state regulation.
[0073] Furthermore, the present invention also provides a method for preparing humidity-pH stimulus responsive room temperature phosphorescent paper, comprising the following steps: forming an aqueous dispersion from the above-mentioned humidity-pH stimulus responsive room temperature phosphorescent paper preparation raw materials, then sheeting into paper, and drying.
[0074] The drying temperature may be 60°C to 80°C, such as 60°C, 65°C, 70°C, 75°C or 80°C, or other values within the range of 60°C to 80°C.
[0075] The drying time may be 6 h to 8 h, such as 6 h, 6.5 h, 7 h, 7.5 h or 8 h, etc., or may be other values within the range of 6 h to 8 h.
[0076] Correspondingly, the present invention also provides a humidity-pH stimulus responsive room temperature phosphorescent paper, which is prepared by the above-mentioned preparation method.
[0077] In some optional embodiments, the basis weight of the humidity-pH stimulus responsive room temperature phosphorescent paper may be 50 g / m 2 ~80g / m2 , such as 50g / m 2 , 55g / m 2 , 60g / m 2 , 65g / m 2 , 70g / m 2 , 75g / m 2 or 80g / m 2 etc., can also be 50g / m 2 ~80g / m 2 Other values within the range.
[0078] In addition, the present invention also provides an application of the above-mentioned humidity-pH stimulus responsive room temperature phosphorescent paper, for example, the humidity-pH stimulus responsive room temperature phosphorescent paper is used in the biomedical field and / or the food field.
[0079] In some optional embodiments, the humidity-pH stimulus responsive room temperature phosphorescent paper can be used to detect or monitor the freshness of food.
[0080] In some optional embodiments, the humidity-pH stimulus responsive room temperature phosphorescent paper can be used to detect or monitor humidity in a biomedical environment or a food environment.
[0081] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.
[0082] Example 1
[0083] This embodiment provides a humidity-pH stimulus responsive room temperature phosphorescent paper, the preparation of which includes:
[0084] S1: Synthesis of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride.
[0085] 1.2 mL (18.15 mmol) of ethylenediamine was added to a 50 mL ethanol suspension containing 1.2 g (6.05 mmol) of BrNpA, and the reaction was refluxed for 4 h. The completion of the reaction was monitored by thin layer chromatography. The mixture obtained by the reflux reaction was then filtered, and the filtrate was cooled to room temperature and filtered again to obtain a crude product. The crude product was then purified by ethanol recrystallization to obtain 700 mg (48%) of 4-bromo-N-(β-ethylamine)-1,8-naphthalimide as a slightly yellow solid.
[0086] S2: Prepare raw materials for humidity-pH stimulus responsive room temperature phosphorescent paper.
[0087] 0.1 g of wood pulp cellulose fiber was dispersed in 45 ml of deionized water, and then 5 mL of DMSO solution containing 0.001 g of 4-bromo-N-(β-ethylamine)-1,8-naphthaleneimide was added, stirred at room temperature for 6 h, and then centrifuged at 6000 r / min and rinsed with deionized water. The above centrifugal washing was repeated twice to obtain a phosphorescent small molecule combined with cellulose product (i.e., raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper).
[0088] S3: Preparation of room temperature phosphorescent paper with humidity-pH stimulus responsive properties.
[0089] The above-prepared raw materials were dispersed in 50 mL of water to form a stable aqueous suspension. The suspension was poured onto filter paper in a sand core funnel with a diameter of 50 mm for suction filtration. Then it was dried in an oven at 60°C for 6 hours to produce room temperature phosphorescent paper (quantitative 50 g / m 2 ).
[0090] Example 2
[0091] This embodiment provides a humidity-pH stimulus responsive room temperature phosphorescent paper, the preparation of which includes:
[0092] S1: Synthesis of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride.
[0093] 1.55 mL (15.13 mmol) of dibutyleneamine was added to a 50 mL ethanol suspension containing 1.2 g (6.05 mmol) of BrNpA, and the reaction was refluxed for 4.5 h. The completion of the reaction was monitored by thin layer chromatography. The hot reaction mixture was then filtered, and the filtrate was cooled to room temperature and filtered again to obtain a crude product. The crude product was then purified by recrystallization from ethanol to obtain about 1 g (40%) of 4-bromo-N-(β-butylamine)-1,8-naphthaleneimide as a slightly yellow solid.
[0094] S2: Prepare raw materials for humidity-pH stimulus responsive room temperature phosphorescent paper.
[0095] 0.12 g of bamboo pulp cellulose fiber was dispersed in 45 ml of deionized water, and then 5 mL of DMSO solution containing 0.002 g of 4-bromo-N-(β-butylamine)-1,8-naphthaleneimide was added, stirred at room temperature for 4 h, and then centrifuged at 5000 r / min and rinsed with deionized water. The above centrifugal washing was repeated once to obtain a phosphorescent small molecule combined with cellulose product (i.e., raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper).
[0096] S3: Preparation of room temperature phosphorescent paper with humidity-pH stimulus responsive properties.
[0097] The above-prepared raw materials were dispersed in 50 mL of water to form a stable aqueous suspension. The suspension was poured onto filter paper in a sand core funnel with a diameter of 50 mm for suction filtration. Then it was dried in an oven at 70°C for 8 hours to produce room temperature phosphorescent paper (quantitative 60 g / m 2 ).
[0098] Example 3
[0099] This embodiment provides a humidity-pH stimulus responsive room temperature phosphorescent paper, the preparation of which includes:
[0100] S1: Synthesis of nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride.
[0101] 1.6 mL (24.2 mmol) of ethylenediamine was added to a 50 mL ethanol suspension containing 1.2 g (6.05 mmol) of BrNpA, and the reaction was refluxed for 5 h. The completion of the reaction was monitored by thin layer chromatography. The hot reaction mixture was then filtered, and the filtrate was cooled to room temperature and filtered again to obtain a crude product. The crude product was then purified by recrystallization from ethanol to obtain about 1.3 g (50%) of 4-bromo-N-(β-ethylamine)-1,8-naphthalimide as a slightly yellow solid.
[0102] S2: Prepare raw materials for humidity-pH stimulus responsive room temperature phosphorescent paper.
[0103] 0.15 g of cotton pulp cellulose fiber was dispersed in 45 ml of deionized water, and then 5 mL of DMSO solution containing 0.003 g of 4-bromo-N-(β-ethylamine)-1,8-naphthaleneimide was added, stirred at room temperature for 8 h, and then centrifuged at 8000 r / min and rinsed with deionized water. The above centrifugal washing was repeated twice to obtain a phosphorescent small molecule combined with cellulose product (i.e., raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper).
[0104] S3: Preparation of room temperature phosphorescent paper with humidity-pH stimulus responsive properties.
[0105] The above-prepared raw materials were dispersed in 50 mL of water to form a stable aqueous suspension. The suspension was poured onto filter paper in a sand core funnel with a diameter of 50 mm for suction filtration. Then it was dried in an oven at 80°C for 7 hours to produce room temperature phosphorescent paper (quantitative 75 g / m 2 ).
[0106] Test example
[0107] Taking Example 1 as an example, the structure of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 was characterized by hydrogen nuclear magnetic resonance spectroscopy and infrared spectroscopy. The results are as follows: Figure 1 and Figure 2 As shown. Figure 1 and Figure 2 It can be proved that ethylenediamine successfully reacts with 4-bromo-1,8-naphthalene dicarboxylic anhydride to generate nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride.
[0108] The excitation spectrum and emission spectrum of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride prepared in Example 1 were analyzed, and the photophysical properties of BrNpE dispersed in aqueous solution were studied. The results are as follows: Figure 3 As shown. Figure 3 It can be seen that BrNpE in aqueous solution exhibits typical excitation-dependent fluorescence characteristics, with maximum emission at 436nm under excitation at 365nm. Its aqueous solution is nearly transparent under sunlight and exhibits blue fluorescence under 365nm ultraviolet light.
[0109] After nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride was physically mixed with cellulose to make paper, the structure of the cellulose before and after modification was characterized and analyzed by infrared spectroscopy. The results are as follows: Figure 4 As shown. Figure 4 It can be seen that compared with the original cellulose paper, the modified cellulose (cellulose combined with naphthalene imide) has -NH 2 The characteristic absorption peak of -1 The absorption peak intensity of the nearby -OH group becomes stronger and shifts to a lower wave number. This can be explained by the nature of hydrogen bonding: the hydrogen-bonded OH group causes v O-H The band is larger than the corresponding v without hydrogen bond O-H The stronger the hydrogen bond, the stronger the corresponding v O-H The stronger the band, the greater the shift to lower wavenumbers. This means that at 3450cm -1 In the region, a small part of the OH band or lower wavenumbers can be assigned to the weak hydrogen bond between amine and hydroxyl groups. O-H model.
[0110] Combination Figure 5 The optical results of the room temperature phosphorescent paper prepared in Example 1 as it changes with humidity are analyzed. Figure 5 It can be seen that under dry conditions, the UV light irradiation shows orange-red luminescence, and under 100% humidity conditions, the UV light irradiation shows blue luminescence. Figure 6 ), the blue luminescence main wavelength 435nm luminescence lifetime is about 3.3ns (such as Figure 7 ), the orange-red main wavelength of 565nm has a lifetime of about 6.3ms (such as Figure 8), which fully demonstrates that blue luminescence belongs to fluorescence and orange-red luminescence belongs to phosphorescence. Since water molecules can easily destroy hydrogen bonds, the breaking of hydrogen bonds and the vibration of water molecules will destroy the stability of triplet excitons and thus reduce the intensity of phosphorescence. Therefore, in a high humidity environment, the paper chip only exhibits blue fluorescence, rather than orange-red phosphorescence, and the paper can restore its room temperature phosphorescence properties after drying. The weak non-covalent hydrogen bond between cellulose and room temperature phosphorescent small molecules can be used as a reaction site to reversibly regulate the luminescence properties to construct a reversible humidity-responsive paper chip. In addition, it has been found that the prepared nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride molecules have pH response characteristics. After cellulose is combined with naphthalimide, the pH response characteristics of the luminescent material itself are maintained (such as Figures 9 to 11 ). Thus, humidity-pH stimulus-responsive room temperature phosphorescent paper was successfully prepared through molecular confinement excited state regulation.
[0111] In summary, the solution provided by the present invention has at least the following advantages:
[0112] (1) 4-Bromo-1,8-naphthalene dicarboxylic anhydride was used as the precursor of the room temperature phosphorescent small molecule. Considering that its fluorescence intensity was weak, the 4-position of the naphthalene ring was first modified with an electron donating group amino to form a strong electron donating-withdrawing system, thereby generating strong fluorescence.
[0113] (2) By utilizing the long polymer chains of the polymer matrix (such as lignocellulose fibers), the room temperature phosphorescent small molecules are introduced into the polymer by simple blending. Since the polymer matrix can provide a large number of hydrogen bonds, it is beneficial to the fixation of the room temperature phosphorescent small molecules and can play a certain isolation effect, inhibiting the non-radiative transition of the room temperature phosphorescent small molecules, thereby helping to achieve the excitation of room temperature phosphorescence of the composite material based on the polymer matrix (i.e., the raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper) and realize strong room temperature phosphorescence.
[0114] (3) Water molecules can easily destroy the hydrogen bonds between the polymer matrix and the room temperature phosphorescent small molecules. The breaking of hydrogen bonds and the vibration of water molecules will destroy the stability of triplet excitons and thus reduce the phosphorescence intensity. Therefore, the weak non-covalent hydrogen bond between the polymer matrix and the room temperature phosphorescent small molecules can be used as a reaction site to reversibly regulate the luminescence properties and construct a reversible humidity-responsive room temperature phosphorescent paper.
[0115] (4) Nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride molecules have pH-responsive properties. After the polymer matrix is combined with the room temperature phosphorescent small molecule through weak hydrogen bonds, the fluorescence-pH response properties of the room temperature phosphorescent small molecule itself are still maintained. When the paper is in an acidic or alkaline environment, the water molecules destroy the weak hydrogen bonds between the polymer matrix and the room temperature phosphorescent small molecule, so the fluorescence-pH response properties of the phosphorescent small molecule itself are presented. Based on this, humidity-pH stimulus-responsive room temperature phosphorescent paper was successfully prepared through molecular confined excited state regulation.
[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for preparing raw materials for humidity-pH stimulus responsive room temperature phosphorescent paper, characterized in that: The method comprises the following steps: mixing nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride with a polymer matrix.
2. The preparation method according to claim 1, characterized in that: The preparation of the raw material for preparing the humidity-pH stimulus responsive room temperature phosphorescent paper includes at least one of the following features: Feature 1: The polymer matrix includes plant cellulose; preferably, the plant cellulose includes at least one of wood pulp, bamboo pulp and cotton pulp; Feature 2: The mass ratio of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride to the polymer matrix is 0.5:100 to 2:100; Feature 3: The nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix are mixed in a physical blending manner.
3. The preparation method according to claim 2, characterized in that: The physical blending of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix comprises: forming a solution of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride, adding the solution into the aqueous dispersion of the polymer matrix and stirring and mixing the solution; Preferably, the stirring and mixing time is 0.5h to 8h; Preferably, the stirring and mixing temperature is 10°C to 60°C; Preferably, the solvent in the solution of nitrogen-substituted 4-bromo-1,8-naphthoic anhydride comprises dimethyl sulfoxide; Preferably, the solid content of the aqueous dispersion of the polymer matrix is 0.1 wt% to 0.5 wt%.
4. The preparation method according to any one of claims 1 to 3, characterized in that: The preparation of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride comprises the following steps: subjecting 4-bromo-1,8-naphthalene dicarboxylic anhydride and an amine-based small molecule to an alcohol reflux reaction.
5. The preparation method according to claim 4, characterized in that: The preparation of the nitrogen-substituted 4-bromo-1,8-naphthalene dicarboxylic anhydride includes at least one of the following features: Feature 4: The amine-based small molecule includes a diamine compound; preferably, the diamine compound includes at least one of ethylenediamine and butanediamine; Feature 5: The molar ratio of the 4-bromo-1,8-naphthalene dicarboxylic anhydride to the amino small molecule is 1:2.5 to 1:4; Feature 6: The reaction time of the 4-bromo-1,8-naphthalene dicarboxylic anhydride and the amino small molecule is 4 to 5 hours.
6. The preparation method according to claim 1, characterized in that: Also includes: Centrifugally washing the mixture of the 4-bromo-1,8-naphthalene dicarboxylic anhydride and the polymer matrix; Preferably, the centrifugal washing is carried out at 5000 r / min to 8000 r / min.
7. A raw material for preparing humidity-pH stimulus responsive room temperature phosphorescent paper, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 6.
8. A method for preparing humidity-pH stimulus responsive room temperature phosphorescent paper, characterized in that: The method comprises the following steps: forming a water dispersion from the raw material for preparing the humidity-pH stimulus responsive room temperature phosphorescent paper according to claim 7, then sheeting the paper, and drying; Preferably, the drying temperature is 60°C to 80°C; Preferably, the drying time is 6 h to 8 h.
9. A humidity-pH stimulus responsive room temperature phosphorescent paper, characterized in that: Prepared by the preparation method according to claim 8; Preferably, the humidity-pH stimulus responsive room temperature phosphorescent paper has a basis weight of 50 g / m 2 ~80g / m 2 .
10. An application of the humidity-pH stimulus responsive room temperature phosphorescent paper as claimed in claim 9, characterized in that: The humidity-pH stimulus responsive room temperature phosphorescent paper is used in the biomedical field and / or the food field; Preferably, the humidity-pH stimulus-responsive room temperature phosphorescent paper is used for detecting or monitoring the freshness of food; Preferably, the humidity-pH stimulus responsive room temperature phosphorescent paper is used for detecting or monitoring humidity in a biomedical environment or a food environment.