Synthesis and Application of Multifunctional Stimuli-Responsive Aggregation-Induced Emission Enhancement Probes

Abstract

The present invention provides the synthesis and application of a group of multiple stimulus-responsive aggregation-induced emission enhancement probes, belonging to the field of aggregation-induced emission materials. Through a simple three-step method, a D-π-A type molecular skeleton is constructed in the molecule, and a group of pyranone-type aggregation-induced emission enhancement probes are synthesized. This group of probes can undergo non-interfering changes in fluorescence color or intensity under multiple stimuli such as solvents, pressure, humidity, and pH. On the one hand, it makes up for the relatively single variety of AIE template molecules; on the other hand, it breaks through the technical barrier of single response of aggregation-induced emission probes, realizing the possibility that the same molecule can simultaneously respond non-interferingly to multiple external stimuli. The preparation method of this probe is simple, with high yield and sensitive and rapid fluorescence response, and is suitable for various application needs.

Description

Technical Field

[0001] The present invention relates to the field of fluorescent probes, and particularly to the synthesis and application of a multiple stimulus-responsive AIE probe. Background Art

[0002] Stimulus-responsive fluorescent materials are a class of intelligent materials whose color changes under external conditions such as light, electricity, heat, solvents, pressure, pH, humidity, etc. Traditional stimulus-responsive fluorescent materials have the aggregation-caused quenching effect (ACQ), which causes fluorescence quenching of fluorescent probes in the aggregated state, thus greatly hindering the application of traditional fluorescent probes. As a new type of probe molecule, aggregation-induced emission probes (AIE) can emit strong fluorescence in the aggregated state, and have many advantages such as high fluorescence quantum yield, rapid response, good stability, etc., thus opening up a new world of fluorescent probes. Although AIE probes have many advantages, their synthesis raw materials are expensive, the synthesis process is complex, and generally they can only respond to a single stimulus. Therefore, it is urgent to develop an AIE probe with a simple synthesis process and capable of achieving multiple non-interfering stimuli responses. Summary of the Invention

[0003] The purpose of the present invention is to provide a group of multiple stimulus-responsive aggregation-induced emission probes and their preparation methods. This group of probes exhibits the aggregation-induced emission enhancement effect (AEE), that is, they can exhibit fluorescence emission both in liquid and solid states, and the fluorescence intensity increases with the increase of the aggregation degree. In addition, this group of probes can produce multiple non-interfering responses to pressure, solvents, humidity, and acids and bases, filling the gap of multiple stimulus-responsive AIE probes.

[0004] A group of multiple stimulus-responsive AEE probes, whose structural formulas are as follows:

[0005]

[0006] The present invention also provides a preparation method of the multiple stimulus-responsive AEE probes:

[0007] Synthesis of intermediates, the synthesis steps and routes are as follows:

[0008] (1) Synthesis of intermediate A:

[0009] Add 1 - 5 mol of 2 - acetylpyridine and 1 - 5 mol of 4 - (diphenylamino) - benzaldehyde to a flask, along with 5 - 10 mL of a solvent and an appropriate amount of a 10% alkali solution by mass. Dissolve the above reaction materials in 60 - 80 mL of an alcohol solution and reflux for 2 h. After washing, column - chromatograph with ethyl acetate / petroleum ether to obtain yellow solid A with a yield of 81 - 85%. 1H NMR (400 MHz, CDCl3) δ 8.80–8.70 (m, 1H), 8.20 (dd, J = 14.3, 11.9 Hz, 2H), 7.98–7.83 (m, 2H), 7.61 (d, J = 8.7 Hz, 2H), 7.50 (ddd, J = 7.5, 4.8, 1.2 Hz, 1H), 7.37–7.29 (m, 4H), 7.21–7.09 (m, 6H), 7.09–6.98 (m, 2H).

[0010] (2) Synthesis of intermediate B:

[0011] Add 1 - 5 mol of 2 - acetylpyridine and 1 - 5 mol of 5 - (4 - (diphenylamino)phenyl)thiophene - 2 - carboxaldehyde to a flask, along with 5 - 10 mL of a solvent and an appropriate amount of a 10% alkali solution by mass. Dissolve the above reaction materials in 60 - 80 mL of an alcohol solution and reflux for 2 h. After washing, column - chromatograph with ethyl acetate / petroleum ether to obtain red solid B with a yield of 62 - 65%. 1H NMR (400 MHz, CDCl3) δ 8..83–8.75 (m, 1H), 8.21 (d, J = 7.8 Hz, 1H), 8.06 (s, 2H), 7.95–7.86 (m, 1H), 7.59–7.47 (m, 3H), 7.37 (dd, J = 9.3, 4.5 Hz, 1H), 7.35–7.29 (m, 4H), 7.24 (d, J = 3.9 Hz, 1H), 7.16 (dd, J = 8.5, 1.0 Hz, 4H), 7.10 (ddd, J = 8.6, 4.3, 1.4 Hz, 4H).

[0012] (3) Synthesis of intermediate C:

[0013] Add 1 - 5 mol of 3 - acetylpyridine and 1 - 5 mol of 5-(4-(diphenylamino)phenyl)thiophene - 2 - carbaldehyde to a flask, along with 5 - 10 mL of a solvent and an appropriate amount of a 10% alkali solution by mass fraction. Dissolve the above reaction materials in 60 - 80 mL of an alcohol solution and stir at 25 - 40 °C for 6 - 8 h. After washing, perform column chromatography with ethyl acetate / petroleum ether to obtain a red solid C with a yield of 27 - 30%. 1H NMR (400 MHz, CDCl3) δ 9.25 (d, J = 1.7 Hz, 1H), 8.82 (dd, J = 4.8, 1.5 Hz, 1H), 8.31 (dt, J = 7.9, 1.8 Hz, 1H), 7.99 (d, J = 15.1 Hz, 1H), 7.57–7.45 (m, 3H), 7.38 (d, J = 3.8 Hz, 1H), 7.32 (t, J = 7.8 Hz, 4H), 7.28–7.23 (m, 2H), 7.16 (d, J = 7.7 Hz, 4H), 7.11 (t, J = 7.9 Hz, 4H).

[0014] (4) Synthesis of Intermediate 1: Add 2.5 mol of 2,6 - dimethyl - 4 - pyranone and 3 mol of 1,3 - indanedione to a three - necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with a 30% sodium hydroxide aqueous solution by mass fraction. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with a saturated NaCl aqueous solution (500 mL). Dry over anhydrous sodium sulfate and concentrate to obtain a crude product. Column chromatography separation (petroleum ether / ethyl acetate) gives a yellow Intermediate 1 with a yield of 75 - 78%.

[0015] Among them, the solvent described in the synthesis steps of Intermediate A, B, and C is one or more of tetrahydrofuran, 1,4 - dioxane, and diethyl ether;

[0016] The alkali described in the synthesis steps of Intermediate A, B, and C is one or more of sodium hydroxide, potassium hydroxide, and sodium ethoxide;

[0017] The alcohol solution described in the synthesis steps of Intermediate A, B, and C is one or more of ethanol, methanol, and butanol;

[0018]

[0019] Synthesis of the product, the synthesis steps and routes are as follows:

[0020] (1) Synthesis of the multiple - stimulus - responsive AEE probe A - A:

[0021] Add 1 - 2 mol of intermediate 1 and 5 - 15 mol of A, and 150 mL of acetonitrile into a three - necked flask. Quickly add a certain amount of piperidine to the reaction solution and reflux the reaction for 20 - 24 h under a nitrogen atmosphere. Cool to room temperature, separate by column chromatography in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in a recrystallization solvent to obtain the target product A - A with a yield of 61 - 63%. HRMS(ESI): calcd for C68H48N4O3: 969.3726(M + H)+.

[0022] (2) Synthesis of multi - stimulus - responsive AEE probe B - B:

[0023] Add 1 - 2 mol of intermediate 1 and 5 - 15 mol of B, and 150 mL of acetonitrile into a three - necked flask. Quickly add a certain amount of piperidine to the reaction solution and reflux the reaction for 20 - 24 h under a nitrogen atmosphere. Cool to room temperature, separate by column chromatography in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in a recrystallization solvent to obtain the target product B - B with a yield of 63 - 67%. HRMS(ESI): calcd for C76H52N4O3S2: 1133.3481(M + H)+.

[0024] (3) Synthesis of multi - stimulus - responsive AEE probe C - C:

[0025] Add 1 - 2 mol of intermediate 1 and 5 - 15 mol of C, and 150 mL of acetonitrile into a three - necked flask. Quickly add a certain amount of piperidine to the reaction solution and reflux the reaction for 20 - 24 h under a nitrogen atmosphere. Cool to room temperature, separate by column chromatography in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in a recrystallization solvent to obtain the target product C - C with a yield of 65 - 67%. HRMS(ESI): calcd for C76H52N4O3S2: 1133.3481(M + H)+.

[0026] In the synthesis steps of the multi - stimulus - responsive AEE probes A - A, B - B and C - C, the recrystallization solvent is one or more of ethanol, acetone or methanol.

[0027]

[0028] Meanwhile, the present invention also provides a non - interfering application of the multi - stimulus - responsive aggregation - induced emission enhancement probe in detecting pressure, solvent, humidity and acid - base.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: By a simple three-step method, a D-π-A molecular skeleton is constructed in the molecule, endowing the molecule with an intramolecular charge transfer effect and good solvatochromic properties. At the same time, this group of probes can exhibit fluorescence emission both in solution and in the solid state, with an aggregation-induced emission enhancement effect, realizing the fluorescence response of the probe molecule in different environmental systems. In addition, after applying pressure, A-A, B-B, and C-C all exhibit excellent pressure-induced color change effects under ultraviolet light irradiation, changing from red to dark red, and can restore the original fluorescence color under the conditions of solvent fumigation or heating to achieve cyclic indication. As the relative humidity in the air increases from 10% to 90%, the fluorescence intensities of the above probes all show a downward trend, enabling humidity monitoring in a wide range. In addition, when HCl gas is introduced into a container containing three solids, the fluorescence colors of the three solids change from red to orange-red, and the discolored fluorescent probes can return to their original colors under the condition of introducing an equal amount of ammonia gas. The synthetic raw materials of the multiple-response AEE-type fluorescent probe molecule of the present invention are cheap and easily available, the route is simple, and the produced probe molecule can simultaneously respond to different solvents, pressure, humidity, and pH in a non-interfering manner, enabling the operator to judge the changes of different factors in the environment through the changes in fluorescence color and intensity. On the one hand, it improves the shortcoming of the single template of the AIE probe molecule, and on the other hand, it fills the gap of the single response of the AIE probe, and can be applied to various needs. Description of the Drawings

[0030] Figure 1 Fluorescence spectra of A-A in dichloromethane-n-hexane with different volume ratios.

[0031] Figure 2 Fluorescence spectra of B-B in dichloromethane-n-hexane with different volume ratios.

[0032] Figure 3 Fluorescence spectra of C-C in dichloromethane-n-hexane with different volume ratios.

[0033] Figure 4 Fluorescence spectra of A-A in cyclohexane, toluene, tetrahydrofuran, and dichloromethane.

[0034] Figure 5 Fluorescence spectra of B-B in cyclohexane, toluene, tetrahydrofuran, and dichloromethane.

[0035] Figure 6 Fluorescence spectra of C-C in cyclohexane, toluene, tetrahydrofuran, and dichloromethane.

[0036] Figure 7 Fluorescence emission spectra of A-A at different relative humidities.

[0037] Figure 8 is the fluorescence emission spectrum of B-B at different relative humidities.

[0038] Figure 9 is the fluorescence emission spectrum of C-C at different relative humidities. Detailed implementation manners

[0039] To better illustrate the invention purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0040] Example 1 Synthesis of multiple-stimulus-responsive AEE probe A-A

[0041] Synthesis of intermediate 1: Add 2.5 mol of 2,6-dimethyl-4-pyrone and 3 mol of 1,3-indanedione into a three-necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with 30% sodium hydroxide aqueous solution by mass fraction. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with saturated NaCl aqueous solution (500 mL). Dry with anhydrous sodium sulfate and concentrate to obtain a crude product. The yellow intermediate 1 can be obtained by column chromatography separation (petroleum ether / ethyl acetate).

[0042] Synthesis of intermediate A: Add 1 mol of 2-acetylpyridine, 2 mol of 4-(diphenylamino)-benzaldehyde, 6 mL of tetrahydrofuran and an appropriate amount of 10% sodium hydroxide solution by mass fraction into a flask. Dissolve the above reaction materials in 65 mL of butanol solution and heat to reflux for 2 h. After washing, pass through a column with ethyl acetate / petroleum ether to obtain yellow solid A with a yield of 82%.

[0043] Synthesis of multiple-stimulus-responsive AEE probe A-A: Add 1 mol of intermediate 1 and 6 mol of A, and 150 mL of acetonitrile into a three-necked flask. Quickly add a certain amount of piperidine to the reaction solution and reflux for 20 h under a nitrogen atmosphere. Cool to room temperature, separate by column chromatography in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in acetone / methanol to obtain the target product A-A with a yield of 62%.

[0044] Example 2 Synthesis of multiple-stimulus-responsive probe A-A

[0045] Synthesis of Intermediate 1: Add 2.5 mol of 2,6-dimethyl-4-pyrone and 3 mol of 1,3-indandione into a three-necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with an aqueous sodium hydroxide solution with a mass fraction of 30%. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with a saturated NaCl aqueous solution (500 mL). Dry over anhydrous sodium sulfate and concentrate to obtain the crude product. The yellow Intermediate 1 can be obtained by column chromatography separation (petroleum ether / ethyl acetate).

[0046] Synthesis of Intermediate A: Add 5 mol of 2-acetylpyridine, 5 mol of 4-(diphenylamino)-benzaldehyde, 10 mL of 1,4-dioxane and an appropriate amount of a potassium hydroxide solution with a mass fraction of 10% into a flask. Dissolve the above reaction materials in 80 mL of methanol solution and reflux for 2 h. After washing, carry out column chromatography with ethyl acetate / petroleum ether to obtain the yellow solid A with a yield of 83%.

[0047] Synthesis of the multiple stimulus-responsive AEE probe A-A:

[0048] Add 2 mol of Intermediate 1 and 14 mol of A1 into a three-necked flask, and 150 mL of acetonitrile. Rapidly add a certain amount of piperidine to the reaction solution and reflux for 24 h under a nitrogen atmosphere. Cool to room temperature, carry out column chromatography separation in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in acetone / ethanol to obtain the target product A-A with a yield of 61%.

[0049] Example 3 Synthesis of the multiple stimulus-responsive AEE probe B-B

[0050] Synthesis of Intermediate 1: Add 2.5 mol of 2,6-dimethyl-4-pyrone and 3 mol of 1,3-indandione into a three-necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with an aqueous sodium hydroxide solution with a mass fraction of 30%. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with a saturated NaCl aqueous solution (500 mL). Dry over anhydrous sodium sulfate and concentrate to obtain the crude product. The yellow Intermediate 1 can be obtained by column chromatography separation (petroleum ether / ethyl acetate).

[0051] Synthesis of Intermediate B: Add 1.5 mol of 2-acetylpyridine and 3 mol of 5-(4-(diphenylamino)phenyl)thiophene-2-carbaldehyde, 6 mL of ether and an appropriate amount of a sodium ethoxide solution with a mass fraction of 10% into a flask. Dissolve the above reaction materials in 60 mL of ethanol solution and reflux for 2 h. After washing, carry out column chromatography with ethyl acetate / petroleum ether to obtain the red solid B with a yield of 63%.

[0052] Synthesis of the multiple stimulus-responsive AEE probe B-B:

[0053] Add 1 mol of intermediate 1, 6 mol of B, and 150 mL of acetonitrile to a three-necked flask. Rapidly add a certain amount of piperidine to the reaction solution and reflux the reaction for 20 h under a nitrogen atmosphere. Cool to room temperature, separate by column chromatography in a mixed solution of petroleum ether / ethyl acetate, and recrystallize from acetone to obtain the target product B-B with a yield of 63%.

[0054] Synthesis of Multifunctional Stimulus-Responsive AEE Probe B-B in Example 4

[0055] Synthesis of intermediate 1: Add 2.5 mol of 2,6-dimethyl-4-pyrone and 3 mol of 1,3-indandione to a three-necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 h, and adjust the pH to neutral with a 30% sodium hydroxide aqueous solution by mass. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with a saturated NaCl aqueous solution (500 mL). Dry over anhydrous sodium sulfate and concentrate to obtain the crude product. The yellow intermediate 1 can be obtained by column chromatography separation (petroleum ether / ethyl acetate).

[0056] Synthesis of intermediate B: Add 5 mol of 2-acetylpyridine and 5 mol of 5-(4-(diphenylamino)phenyl)thiophene-2-carbaldehyde to a flask, 6 mL of diethyl ether, 4 mL of tetrahydrofuran, and an appropriate amount of a 10% sodium hydroxide solution by mass. Dissolve the above reaction materials in 80 mL of butanol solution and reflux for 2 h. After washing, pass through a column with ethyl acetate / petroleum ether to obtain the red solid B with a yield of 65%.

[0057] Synthesis of Multifunctional Stimulus-Responsive AEE Probe B-B:

[0058] Add 2 mol of intermediate 1 and 14 mol of B to a three-necked flask, and 150 mL of acetonitrile. Rapidly add a certain amount of piperidine to the reaction solution and reflux the reaction for 24 h under a nitrogen atmosphere. Cool to room temperature, separate by column chromatography in a mixed solution of petroleum ether / ethyl acetate, and recrystallize from acetone / methanol to obtain the target product B-B with a yield of 66%.

[0059] Synthesis of Multifunctional Stimulus-Responsive AEE Probe C-C in Example 5

[0060] Synthesis of Intermediate 1: Add 2,6-dimethyl-4-pyrone (2.5 mol) and 1,3-indandione (3 mol) into a three-necked flask, and then add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with an aqueous sodium hydroxide solution with a mass fraction of 30%. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with saturated NaCl aqueous solution (500 mL). Dry over anhydrous sodium sulfate and concentrate to obtain the crude product. The yellow Intermediate 1 can be obtained by column chromatography separation (petroleum ether / ethyl acetate).

[0061] Synthesis of Intermediate C:

[0062] Add 1 mol of 3-acetylpyridine and 2 mol of 5-(4-(diphenylamino)phenyl)thiophene-2-carbaldehyde, 6 mL of tetrahydrofuran and an appropriate amount of potassium hydroxide solution with a mass fraction of 10% into a flask. Dissolve the above reaction materials in a mixed solution of 30 mL of methanol and 37 mL of ethanol and stir at 30 °C for 6 h. After washing, carry out column chromatography with ethyl acetate / petroleum ether to obtain the red solid C with a yield of 27%.

[0063] Synthesis of Multifunctional Stimuli-Responsive AEE Probe C-C:

[0064] Add 1 mol of Intermediate 1 and 5 mol of C, and 150 mL of acetonitrile into a three-necked flask. Quickly add a certain amount of piperidine to the reaction solution and reflux under a nitrogen atmosphere for 21 h. Cool to room temperature, carry out column chromatography separation in a mixed solution of petroleum ether / ethyl acetate, and recrystallize from acetone to obtain the target product C-C with a yield of 66%.

[0065] Example 6 Synthesis of Multifunctional Stimuli-Responsive AEE Probe C-C

[0066] Synthesis of Intermediate 1: Add 2,6-dimethyl-4-pyrone (2.5 mol) and 1,3-indandione (3 mol) into a three-necked flask, and then add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with an aqueous sodium hydroxide solution with a mass fraction of 30%. Extract with ethyl acetate (200 mL) three times, combine the organic phases, and wash five times with saturated NaCl aqueous solution (500 mL). Dry over anhydrous sodium sulfate and concentrate to obtain the crude product. The yellow Intermediate 1 can be obtained by column chromatography separation (petroleum ether / ethyl acetate).

[0067] Synthesis of Intermediate C:

[0068] Add 5 mol of 3-acetylpyridine and 5 mol of 5-(4-(diphenylamino)phenyl)thiophene-2-carbaldehyde to a flask, 8 mL of 1,4-dioxane and an appropriate amount of a sodium ethoxide solution with a mass fraction of 10%. Dissolve the above reaction materials in 80 mL of an ethanol solution and stir at 40 °C for 8 h. After washing, carry out column chromatography with ethyl acetate / petroleum ether to obtain a red solid C with a yield of 30%.

[0069] Synthesis of the multiple stimulus-responsive AEE probe C-C:

[0070] Add 2 mol of intermediate 1 and 4 mol of C to a three-necked flask, and 150 mL of acetonitrile. Quickly add a certain amount of piperidine to the reaction solution and reflux in a nitrogen environment for 24 h. Cool to room temperature, carry out column chromatography separation in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in methanol to obtain the target product C-C with a yield of 66%.

[0071] Example 7 Aggregation-induced emission performance

[0072] Weigh a certain amount of the sample and prepare a dichloromethane solution with a concentration of 1.0×10-4 mol / L. Place this mother liquor in an ultrasonic cleaner and slowly add n-hexane to prepare solutions with n-hexane contents of 0%, 10%, 20%... 90%. After preparation, immediately measure the liquid fluorescence with a Hitachi F-2500 fluorescence spectrophotometer. Among them, the attached Figures 1 - 3 are the liquid fluorescence emission spectra of A-A, B-B, and C-C respectively. As can be seen from the figure, all three probes can exhibit fluorescence emission in both the liquid and aggregated states, showing an aggregation-induced emission enhancement effect. Among them, as the content of the poor solvent increases, the fluorescence intensity gradually increases due to the restricted rotation of the single bonds in the probe; as the poor solvent further increases, amorphous nanoparticles appear in the system and the fluorescence intensity decreases.

[0073] Example 8 Solvatochromic performance

[0074] Weigh a certain amount of the sample and prepare tetrahydrofuran, cyclohexane, toluene, and dichloromethane solutions with a concentration of 1.0×10-4 mol / L respectively. After preparation, immediately measure the liquid fluorescence with a Hitachi F-2500 fluorescence spectrophotometer. It is found that all three probes A-A, B-B, and C-C exhibit excellent solvatochromic effects (attached Figures 4 - 6 ). This is because the molecule has a good electron donor triphenylamine and electron acceptor indanone and pyranone structures, the charge separation degree of the molecule increases, and it can be better stabilized by solvation. The stronger the solvent polarity, the better the stabilization effect on the excited state and ground state of the molecule with a large charge separation degree, resulting in a more obvious red shift of the fluorescence spectrum.

[0075] Example 9 Pressure-Induced Color Change Performance

[0076] Take a certain amount of samples (original samples, ground samples, annealed samples) and place them in a Horiba Jobin Yvon Fluorolog-3 steady-state transient fluorescence infrared comprehensive test spectrometer for solid fluorescence testing. The following table lists the solid fluorescence colors of three probes, A-A, B-B, and C-C, in different states under ultraviolet light irradiation

[0077]

[0078] It can be seen that the three fluorescence probes can all exhibit red fluorescence under ultraviolet light. After grinding with a mortar, all three probes show a red shift in the fluorescence spectrum and emit dark red fluorescence, showing an obvious color change. In addition, after annealing or solvent fumigation of the ground samples, they can change back from dark red to the original red, realizing the cyclic indication of pressure

[0079] Example 10 Determination of Humidity

[0080] Weigh a certain amount of samples and place them in a sealed desiccator. Humidify with a humidifier and keep it unchanged for one hour. Quickly take out the solid samples and place them in a Horiba Jobin Yvon Fluorolog-3 steady-state transient fluorescence infrared comprehensive test spectrometer for solid fluorescence testing. As can be seen from the appendix Figures 7 - 9 As the humidity in the environment increases, all three probes, A-A, B-B, and C-C, show an obvious trend of decreasing fluorescence intensity. The increase in humidity can lead to an increase in the polarity of the environment around the probe molecules. Due to the influence of the intramolecular charge transfer effect, the fluorescence intensity will decrease. In different humidities, all three probes can show extremely sensitive intensity changes, with a wide indication range and rapid response

[0081] Example 11 Acid-Base Indication

[0082] Weigh a certain amount of samples and place them in a sealed desiccator. Alternately introduce HCl and NH3 gases into the desiccator, with each gas introduction time being 30 seconds. Quickly take out the solid samples and place them in a Horiba Jobin Yvon Fluorolog-3 steady-state transient fluorescence infrared comprehensive test spectrometer for solid fluorescence testing. The following table lists the solid fluorescence colors of three probes, A-A, B-B, and C-C, under ultraviolet light irradiation after alternately introducing HCl and NH3 gases

[0083]

[0084]

[0085] After being fumigated with HCl acidic gas, the solid fluorescence colors of the three fluorescent probes all changed from the original red to orange-red, and the solid fumigated with acidic HCl could be restored to the original red under the fumigation of alkaline gas NH3. Repeating the above operations, the same experimental results can be obtained, and this process can be repeated multiple times, indicating that the three probes A-A, B-B, and C-C all have excellent pH sensitivity and fluorescence reversibility. This effect may be due to the change in the electron cloud distribution of the probe molecules in different acid-base environments.

[0086] In summary, through a simple three-step method, the present invention constructs a D-π-A molecular skeleton in the molecule, endowing the molecule with an intramolecular charge transfer effect and good solvatochromic properties. At the same time, this group of probes can exhibit fluorescence emission both in solution and in the solid state, with an aggregation-induced emission enhancement effect, realizing the fluorescence response of the probe molecules in different environmental systems. In addition, after applying pressure, A-A, B-B, and C-C all exhibit excellent pressure-induced color change effects under ultraviolet light irradiation, changing from red to dark red, and can restore the original fluorescence color under the conditions of solvent fumigation or heating to achieve cyclic indication. As the relative humidity in the air increases from 10% to 90%, the fluorescence intensities of the above probes all show a downward trend, enabling humidity monitoring over a wide range. In addition, by introducing HCl gas into the container containing the three solids, the fluorescence colors of the three solids change from red to orange-red, and the discolored fluorescent probes can be restored to the original color under the condition of introducing an equal amount of ammonia gas. The raw materials for synthesizing the multi-responsive AIE-type fluorescent probe molecules of the present invention are inexpensive and easily available, the route is simple, and the produced probe molecules can simultaneously respond non-interferingly to different solvents, pressures, humidities, and pH values, enabling the operator to judge the changes of different factors in the environment through the changes in fluorescence color and intensity. On the one hand, it improves the shortcoming of the single template of AIE probe molecules, and on the other hand, it fills the blank of single response of AIE probes, and can be applied to various needs.

[0087] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations and modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A group of multiple stimulus-responsive aggregation-induced emission enhancement probes, characterized in that, The structures of probes A-A, B-B, and C-C are as follows:

2. A preparation method of the multiple stimulus-responsive aggregation-induced emission enhancement probe according to claim 1, characterized in that, The preparation method of the probe A-A includes: (1) Synthesis of intermediate A: Add 1 - 5 mol of 2-acetylpyridine, 1 - 5 mol of 4-(diphenylamino)-benzaldehyde, 5 - 10 mL of solvent, and an appropriate amount of 10% alkaline solution by mass fraction to a flask. Dissolve the above reaction materials in 60 - 80 mL of alcohol solution, heat under reflux for 2 h, wash, and then perform column chromatography with ethyl acetate / petroleum ether; (2) Synthesis of intermediate 1: Add 2.5 mol of 2,6-dimethyl-4-pyrone and 3 mol of 1,3-indanedione to a three-necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with 30% sodium hydroxide aqueous solution by mass fraction. Extract with 200 mL of ethyl acetate three times, combine the organic phases, wash five times with 500 mL of saturated NaCl aqueous solution, dry with anhydrous sodium sulfate, concentrate to obtain a crude product, and separate by column chromatography with petroleum ether / ethyl acetate to obtain a yellow intermediate 1; (3) Synthesis of probe A-A: Add 1 - 2 mol of intermediate 1 and 5 - 15 mol of A to a three-necked flask, add 150 mL of acetonitrile, quickly add a certain amount of piperidine to the reaction solution, and reflux and react for 20 - 24 h under a nitrogen atmosphere; cool to room temperature, perform column chromatography separation in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in a recrystallization solvent to obtain the target product A-A; Among them, the structures of intermediate A and intermediate 1 are as follows:

3. A preparation method of the multiple stimulus-responsive aggregation-induced emission enhancement probe according to claim 1, characterized in that, The preparation method of the probe B-B includes: (1) Synthesis of intermediate B: Add 1 - 5 mol of 2-acetylpyridine, 1 - 5 mol of 5-(4-(diphenylamino)phenyl)thiophene-2-carbaldehyde, 5 - 10 mL of solvent, and an appropriate amount of 10% alkaline solution by mass fraction to a flask. Dissolve the above reaction materials in 60 - 80 mL of alcohol solution, heat under reflux for 2 h, wash, and then perform column chromatography with ethyl acetate / petroleum ether; (2) Synthesis of intermediate 1: Add 2.5 mol of 2,6-dimethyl-4-pyrone and 3 mol of 1,3-indanedione to a three-necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with 30% sodium hydroxide aqueous solution by mass fraction. Extract with 200 mL of ethyl acetate three times, combine the organic phases, wash five times with 500 mL of saturated NaCl aqueous solution, dry with anhydrous sodium sulfate, concentrate to obtain a crude product; separate by column chromatography with petroleum ether / ethyl acetate to obtain a yellow intermediate 1; (3) Synthesis of probe B-B: Add 1 - 2 mol of intermediate 1 and 5 - 15 mol of B to a three-necked flask, add 150 mL of acetonitrile, quickly add a certain amount of piperidine to the reaction solution, and reflux and react for 20 - 24 h under a nitrogen atmosphere; cool to room temperature, perform column chromatography separation in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in a recrystallization solvent to obtain the target product B-B; Among them, the structures of intermediate B and intermediate 1 are as follows:

4. A preparation method of the multiple stimulus-responsive aggregation-induced emission enhancement probe according to claim 1, characterized in that, The preparation method of the probe C-C includes: (1) Synthesis of Intermediate C: Add 1 - 5 mol of 3 - acetylpyridine and 1 - 5 mol of 5-(4-(diphenylamino)phenyl)thiophene - 2 - carbaldehyde into a flask, 5 - 10 mL of solvent and an appropriate amount of 10% alkaline solution by mass fraction. Dissolve the above reaction materials in 60 - 80 mL of alcohol solution and stir at 25 - 40 °C for 6 - 8 h. After washing, column chromatography is carried out with ethyl acetate / petroleum ether; (2) Synthesis of Intermediate 1: Add 2.5 mol of 2,6 - dimethyl - 4 - pyranone and 3 mol of 1,3 - indandione into a three - necked flask, and add 100 mL of acetic anhydride thereto. React the reaction solution at the reflux temperature for 6 hours, and adjust the pH to neutral with 30% sodium hydroxide aqueous solution by mass fraction. Extract with 200 mL of ethyl acetate for 3 times, combine the organic phases, and wash with 500 mL of saturated NaCl aqueous solution for five times. Dry with anhydrous sodium sulfate and concentrate to obtain the crude product. The yellow Intermediate 1 can be obtained by column chromatography separation with petroleum ether / ethyl acetate; (3) Synthesis of C - C: Add 1 - 2 mol of Intermediate 1 and 5 - 15 mol of C into a three - necked flask, and 150 mL of acetonitrile; quickly add a certain amount of piperidine to the reaction solution and reflux in a nitrogen environment for 20 - 24 h. Cool to room temperature, carry out column chromatography separation in a mixed solution of petroleum ether / ethyl acetate, and recrystallize in the recrystallization solvent to obtain the target product C - C; Among them, the structures of Intermediate C and Intermediate 1 are as follows:

5. The preparation method of the multi-stimulus responsive aggregation-induced emission enhancement probe according to any one of claims 2-4, characterized in that, The solvent described in the synthesis steps of Intermediate A, B, and C is one or more of tetrahydrofuran, 1,4 - dioxane, and diethyl ether.

6. The preparation method of the multi-stimulus responsive aggregation-induced emission enhancement probe according to any one of claims 2-4, characterized in that The base described in the synthesis steps of Intermediate A, B, and C is one or more of sodium hydroxide, potassium hydroxide, and sodium ethoxide.

7. The preparation method of the multi-stimulus responsive aggregation-induced emission enhancement probe according to any one of claims 2-4, characterized in that, The alcohol solution described in the synthesis steps of Intermediate A, B, and C is one or more of ethanol, methanol, and butanol.

8. The preparation method of the multi-stimulus responsive aggregation-induced emission enhancement probe according to any one of claims 2-4, characterized in that The recrystallization solvent in the synthesis steps of the multi - stimulus - responsive aggregation - induced emission enhancement probes A - A, B - B, and C - C is one or more of ethanol, acetone, and methanol.

9. Non - interfering application of the multi - stimulus - responsive aggregation - induced emission enhancement probe according to Claim 1 in detecting pressure, solvent, humidity, and acid - base.

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