Triphenylamine triazine compounds, preparation and use in explosives and drug detection

Abstract

The application provides a triphenylamine-triazine structure compound and a D-A type polytriphenylamine triazine compound and a preparation method and application in drug detection and TNT content detection in water, and belongs to the technical field of drug quality detection and environmental detection in water. The structural formula of the triphenylamine-triazine structure compound is shown in the following formula , and the structural formula of the D-A type polytriphenylamine triazine compound is shown in the following formula <II>, wherein X is --SO2-- or --CO--. The D-A type polytriphenylamine triazine compound has strong light emitting performance, can be well used for detection of drugs such as salbutamol sulfate solution, and can be used for detection of trace TNT. The detection limit of the D-A type polytriphenylamine triazine compound for TNT is very low, and is 39 nM and 70 nM respectively. Meanwhile, the D-A type polytriphenylamine triazine compound shows good anti-interference ability and is hardly affected by potential factors such as pH, other nitro compounds, metal cations and anions.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of drug detection and environmental detection in water bodies, and particularly relates to a compound with a triphenylamine-triazine structure and a D-A type polytriphenylamine triazine compound, a preparation method thereof and application thereof in drug detection and explosive detection. BACKGROUND

[0002] Drug dosage control is the key to ensuring drug efficacy, so the detection of drug dosage or impurities has become a key process to ensure drug quality. For drugs such as salbutamol sulfate solution, the fluorescence detection method is expected to control the quality.

[0003] On the other hand, 2,4,6-trinitrotoluene (TNT) is a powerful explosive and is widely used in military and industrial fields. However, TNT is biologically toxic, difficult to degrade, and has irreversible destructive effects on the environment, so it is particularly important to monitor TNT in the environment.

[0004] In recent years, in the face of the challenges of drug quality control and the detection of nitroaromatic explosives such as TNT in water bodies, various instrument-based analysis techniques have rapidly developed, covering chromatography, mass spectrometry, gas chromatography-mass spectrometry, X-ray imaging, Raman spectroscopy, ion mobility spectrometry, electrochemical analysis and other methods. The emergence of these technologies has greatly promoted the progress of detection technology. However, these devices are often bulky and not easy to carry, making it difficult to meet the needs of real-time, on-site monitoring, especially in outdoor environmental monitoring situations where data needs to be quickly obtained. This limitation not only reduces the efficiency of on-site detection, but also increases the feedback time. In contrast, fluorescence-based detection methods, with their simple operation, low cost, high sensitivity and excellent selectivity, have been applied to portable detection devices since the last century and have therefore been widely used.

[0005] Triphenylamine, as a classic organic semiconductor material, has shown great potential in constructing fluorescent probes due to its unique electron-rich properties, geometric configuration and chemical stability. However, current fluorescent probe materials based on triphenylamine face many challenges, such as complex synthesis, low yield and difficulty in large-scale production.

[0006] Typically, the synthesis of triphenylamine-based polymers requires the pre-introduction of reactive functional groups, followed by polymerization. This method inevitably involves more synthesis steps and higher costs. In addition, unmodified triphenylamine-based polymers exhibit low quantum yields in aqueous media, and often require the modification of aggregation-induced emission (AIE) groups such as tetraphenyl ethylene to enhance the luminescent efficiency of the aggregated state. This limitation seriously affects the application of triphenylamine-based polymers as fluorescent probes for TNT in water.

[0007] Therefore, how to provide a preparation method of triphenylamine polymer with simple preparation method, high yield, good responsiveness to drugs such as salbutamol sulfate solution, low detection limit of TNT in water, and good anti-interference ability, which is almost not affected by potential factors such as pH, other nitro compounds, metal cations and anions, becomes a technical problem to be solved. SUMMARY

[0008] The present application is to solve the above technical problems, and provides a D-A type polytriphenylamine triazine compound and its application in drug detection and TNT content detection in water. To solve the problems of existing triphenylamine polymer, such as complex preparation steps, low quantum yield, insufficient detection sensitivity of salbutamol sulfate solution and TNT, and high detection limit.

[0009] In order to achieve the above technical purpose, the technical scheme adopted by the present application is as follows:

[0010] The present application first provides a compound with triphenylamine-triazine structure, characterized in that the structure formula of the compound with triphenylamine-triazine structure is as follows:

[0011]

[0012] The second object of the present application is to provide a preparation method of the compound with triphenylamine-triazine structure as described above, which is to add dimethyl sulfoxide to a mixture containing 4-hydroxybenzamidine hydrochloride, 4-diphenylamino benzaldehyde and cesium carbonate, heat and react for a period of time, then precipitate the product and extract it for several times to obtain a crude product, and purify the crude product by column chromatography.

[0013] Further, the molar ratio of the 4-hydroxybenzamidine hydrochloride, 4-diphenylamino benzaldehyde and cesium carbonate is 2-2.5:1-1.2:2-2.5.

[0014] Further, the reaction temperature is 120-140℃, and the reaction time is 16-20 hours.

[0015] The third object of the present application is to provide a D-A type polytriphenylamine triazine compound, and the structure formula of the D-A type polytriphenylamine triazine compound is as follows:

[0016]

[0017] Among them, X is --SO2-- or --CO--.

[0018] Further, the average lifetime <τ>avg of the D-A type polytriphenylamine triazine compound is 3.62-3.75 ns, and the fluorescence quantum yield in water is 0.62-0.65. is 0.39-0.53.

[0019] Further, the D-A type polytriphenylamine triazine compound has a thermal decomposition temperature of 538-564 DEG C and a glass transition temperature of 197-220 DEG C.

[0020] Further, the D-A type polytriphenylamine triazine compound has a fluorescence quenching response to a drug salbutamol sulfate solution, and a detection limit of 39 nM and 70 nM for TNT in water, respectively.

[0021] The fourth object of the present application is to provide a preparation method of the D-A type polytriphenylamine triazine compound as described above, which is prepared by a one-step C-O coupling reaction of 4,4'-difluorodiphenyl sulfone and a triphenylamine-triazine structure compound as reaction monomers and potassium carbonate under a nitrogen atmosphere; wherein the reaction monomers are prepared from 4-hydroxybenzamidine hydrochloride, 4-diphenylaminobenzaldehyde and cesium carbonate.

[0022] Further, the molar ratio of the 4,4'-difluorodiphenyl sulfone, the triphenylamine-triazine structure compound and the potassium carbonate is 1-1.2:1-1.2:1.5-2.0.

[0023] Further, the reaction temperature of the C-O coupling reaction is 150-180 DEG C, and the reaction time is 6-12 hours.

[0024] The fifth object of the present application is to provide the application of the triphenylamine-triazine structure compound and the D-A type polytriphenylamine triazine compound as fluorescent probes for the detection of TNT content in water and the detection of a drug salbutamol sulfate solution.

[0025] The present application first synthesizes a monomer of triphenylamine-triazine, and then successfully prepares two polymers by using a C-O coupling reaction. The structure and stability of the polymers are characterized by infrared, nuclear magnetic resonance, thermal analysis and other means, and the photophysical parameters such as ultraviolet-absorption spectrum, fluorescence spectrum, fluorescence lifetime and quantum yield are tested. The D-A type polytriphenylamine triazine compound has high responsiveness to a drug salbutamol sulfate solution, and can be used for drug quality detection; in addition, it has strong luminescence in water, and can be well used for trace TNT detection. The D-A type polytriphenylamine triazine compound has a fluorescence quenching response to a salbutamol sulfate solution, and a detection limit of 39-70 nM for TNT. At the same time, it shows good anti-interference ability and is hardly affected by potential factors such as pH, other nitro compounds, metal cations and anions.

[0026] The present application has the following beneficial effects:

[0027] The D-A type polytriphenylamine triazine compound provided by the application has the advantages of low detection limit and good detection stability in drug detection, such as response to salbutamol sulfate solution, and in detection of explosives, such as TNT in water, and the existing detection methods are all not as good as the compound in the application, and the preparation method is simple and has high yield. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 (a) infrared spectrum (A: 4-hydroxybenzamidine hydrochloride; B: 4-diphenylamino benzaldehyde; C: TPATz-2OH); (b) nuclear magnetic hydrogen spectrum of TPATz-2OH.

[0029] Figure 2 (a) infrared spectrum of PTPATzS and PTPATzK; (b) nuclear magnetic hydrogen spectrum of PTPATzS; (c) nuclear magnetic hydrogen spectrum of PTPATzK.

[0030] Figure 3 TGA (a) and DSC (b) of the polymer.

[0031] Figure 4 (a) ultraviolet-visible absorption spectrum and fluorescence spectrum of the polymer powder; (b) transient fluorescence decay curve of the polymer powder.

[0032] Figure 5 (a) ultraviolet-visible absorption spectrum of PTPATzS; (b) ultraviolet-visible absorption spectrum of PTPATzK; (c) fluorescence spectrum of PTPATzS; (d) fluorescence spectrum of PTPATzK.

[0033] Figure 6 Linear relationship fitting of Stokes shift (Δν) and orientation polarizability (Δf) of solvents of PTPATzS (a) and PTPATzK (b).

[0034] Figure 7 Fluorescence spectra of PTPATzS (a) and PTPATzK (c) in different proportions of THF / H2O; change curves of fluorescence intensity and maximum emission wavelength of PTPATzS (b) and PTPATzK (d) in different proportions of THF / H2O.

[0035] Figure 8 (a) detection of PTPATzS on TNT; (b) Stern-Volmer equation fitting curve of PTPATzS; (c) detection of PTPATzK on TNT; (d) Stern-Volmer equation fitting curve of PTPATzK.

[0036] Figure 9Response time curves of PTPATzS and PTPATzK to TNT.

[0037] Figure 10 (a) The detection of PTPATzS to TNT is affected by pH value; (b) The detection of PTPATzK to TNT is affected by pH value.

[0038] Figure 11 Fluorescence spectra of PTPATzS (a) and PTPATzK (c) after adding different nitro compounds; changes of fluorescence intensity of PTPATzS (b) and PTPATzK (d) after adding different nitro compounds.

[0039] Figure 12 Fluorescence spectra of PTPATzS (a) and PTPATzK (c) after adding different metal ions; changes of fluorescence intensity of PTPATzS (b) and PTPATzK (d) after adding different metal ions.

[0040] Figure 13 Fluorescence spectra of PTPATzS (a) and PTPATzK (b) after adding different anions; changes of fluorescence intensity of PTPATzS (b) and PTPATzK (d) after adding different anions.

[0041] Figure 14 Changes of average particle size and fluorescence intensity of aqueous solution of PTPATzS (a) and PTPATzK (b) within 21 days. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is described in detail below in combination with examples. It is necessary to point out that the following examples are only used to explain and illustrate the present application, and do not limit the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above description still belong to the protection scope of the present application.

[0043] Example 1

[0044] I. Experimental instruments and raw materials

[0045] Table 1 Experimental reagents

[0046]

[0047]

[0048] Note: AR is analytical pure, and SP is four-grade product.

[0049] Table 2 Main experimental equipment

[0050]

[0051] II. Preparation of polymers

[0052] 1. Synthesis of monomer

[0053] As shown in Reaction Formula (I), a compound of triphenylamine-triazine structure was synthesized. Specifically, 4-hydroxybenzamidine hydrochloride (3.80 g, 22 mmol), 4-diphenylaminobenzaldehyde (2.73 g, 10 mmol), and cesium carbonate (8.14 g, 25 mmol) were placed in a three-neck flask equipped with a stirrer. Then, 20 mL of dimethyl sulfoxide solution was added dropwise to the flask, and the reaction mixture was stirred for half an hour to allow the reactants to be fully dissolved. Then, the reaction was performed at 120°C for 18 hours. After the reaction was completed, the resulting reaction solution was poured into water to precipitate the product. The product was filtered and washed with distilled water several times. After the washing was completed, the product was sufficiently extracted with ethyl acetate several times, and then anhydrous sodium sulfate was added to the extract to remove water. The filtrate was collected by filtration, and the solvent was removed by distillation under reduced pressure to obtain a crude product. The crude product was purified by column chromatography (developing agent: a mixture of ethyl acetate and petroleum ether = 1:2, Rf value: 0.3), and recrystallized using methanol. Finally, 2.69 g of a yellow-green crystalline product was obtained after vacuum drying for 5 hours, which was denoted as TPATz-2OH, and the yield was 53%.

[0054]

[0055] 2. Synthesis of polymers

[0056] As shown in Reaction Formula (II), two polytriphenylamine-triazine fluorescent materials were synthesized by C-O coupling, which were denoted as PTPATzS and PTPATzK, respectively. For example, in the preparation of PTPATzS, 4,4'-difluorodiphenyl sulfone (2.54 g, 10 mmol), TPATz-2OH (5.08 g, 10 mmol), and anhydrous potassium carbonate (2.07 g, 15 mmol) were placed in a three-neck flask equipped with a stirrer under a nitrogen atmosphere. Then, 10 mL of sulfolane and 5 mL of chlorobenzene solution were added dropwise, and the reaction mixture was stirred to be uniformly mixed. The reaction was performed at 160°C for 8 hours. After the reaction was completed, the reaction solution was poured into anhydrous ethanol to precipitate the product, which was washed with distilled water several times. The product was extracted with anhydrous ethanol at 80°C for 12 hours using a Soxhlet extractor, and then vacuum dried for 5 hours. As a result, 6.29 g of a yellow powder was obtained, and the yield was 87%.

[0057]

[0058] III. Polymer characterization and performance test method

[0059] (1) Thermal stability

[0060] The DSC and TGA curves of the polymer were obtained in a nitrogen atmosphere at a heating rate of 10 K / min using a Netzsch DSC214 differential scanning calorimeter and a Mettler TGA2 thermal analyzer, respectively.

[0061] (2) Fluorescence properties in different solvents

[0062] 1 mg of polymer was added to a glass bottle containing 20 mL of different solvents (cyclohexane (HEX), chloroform (TCM), ethyl acetate (EA), dichloromethane (DCM), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), ethanol (EtOH), methanol (MeOH)). After complete dissolution, the polymer was excited with 365 nm ultraviolet light to test the fluorescence spectrum of each solvent.

[0063] (3) Fluorescence quantum yield

[0064] Prepare a polymer solution with an absorbance of less than 0.05 at a UV wavelength of 360 nm, using a quinine sulfate solution ( A 0.05 mol / L aqueous solution of H₂SO₄ was used as the reference sample. After measuring the fluorescence spectrum of the polymer in this solvent using a fluorescence spectrometer, its quantum yield was calculated using equation (1-1).

[0065]

[0066] In the formula, st and x represent the standard sample and the sample to be tested, respectively. denoted as fluorescence quantum yield, F is the integral area of ​​the fluorescence peak, f is the absorption factor, and n is the refractive index of the solvent.

[0067] (4) Fluorescence lifetime

[0068] The fluorescence decay curves of the polymer were measured using transient fluorescence spectroscopy, and the fluorescence lifetimes τ1 and τ2 were obtained by second-order exponential fitting. Then, the average fluorescence lifetime (<τ>) was calculated using equation (1-2). avg ).

[0069]

[0070] In the formula, τ1 and τ2 are the fluorescence lifetimes obtained by second-order exponential fitting; B1 and B2 are the proportions of the fluorescence lifetime components τ1 and τ2, respectively; <τ> avg This represents the average fluorescence lifetime.

[0071] (5) Fluorescence properties of the polymer in the H2O / THF dual solvent system

[0072] Prepare 10 mL H2O / THF solution with the ratio of 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9, 0:10 (v / v) respectively, and add 100 μL polymer solution with the concentration of 1 g / L to each solution. After shaking to mix well, test the fluorescence spectrum of the polymer under different water content under 365 nm UV excitation.

[0073] (6) Detection of the polymer to the drug salbutamol sulfate solution and TNT

[0074] 1) Detection of the polymer PTPATzS and PTPATzK to TNT

[0075] Prepare 500 mL polymer solution with the concentration of 0.01 g / L (THF / water = 1:9, v / v), take 10 mL to a glass bottle, and add 0 μL, 0.25 μL, 0.5 μL, 0.75 μL, 1 μL, 1.5 μL, 2 μL, 2.5 μL, 3 μL, 4 μL and 5 μL TNT solution with the concentration of 1 g / L respectively. After equilibration, test the fluorescence spectrum under 365 nm UV excitation. Calculate the Stern-Volmer constant (K SV ) and the limit of detection (LOD) of the polymer to TNT by fitting formula (1-3) and formula (1-4).

[0076]

[0077]

[0078] In the formula, I0 is the initial fluorescence intensity of the fluorescence probe before adding TNT, I is the fluorescence intensity after complete response after adding TNT, [Q] is the concentration of TNT in the sample to be tested, K sv is the Stern-Volmer constant, C L is the limit of detection of the fluorescence probe, and S is the 15 standard deviations of the blank sample.

[0079] 2) Detection of the polymer to the drug salbutamol sulfate solution

[0080] Weigh a certain amount of polymer and transfer it to the commercially available salbutamol sulfate solution, and test the fluorescence spectrum under 365 nm UV excitation.

[0081] (7) Response speed of the polymer to TNT

[0082] A 10 mL solution (H2O / THF = 9:1, v / v) was prepared in a glass bottle, and 10 μL, 20 μL, 40 μL, 60 μL, 80 μL, and 100 μL of a 5 g / L polymer solution were added, respectively. Then, 3.5 mL was taken and added to a cuvette, and 70 μL of a 2 mM TNT solution was also added to the cuvette. The fluorescence intensity of the solution was measured as a function of time under 365 nm UV excitation.

[0083] (8) Effect of pH on polymer performance

[0084] A 10 mL solution (H2O / THF = 9:1, v / v) was prepared in a glass bottle, and 10 μL, 20 μL, 40 μL, 60 μL, 80 μL, and 100 μL of a 5 g / L polymer solution were added, respectively. Then, 3.5 mL was taken and added to a cuvette, and 70 μL of a 2 mM TNT solution was also added to the cuvette. The fluorescence intensity of the solution was measured as a function of time under 365 nm UV excitation.

[0085] (9) Selectivity of polymer for TNT

[0086] A 10 mM solution of metal ion nitrate (Ag + , Al 3+ , Ca 2+ , Co 3+ , Cu 2+ , Fe 2+ , Fe 3+ , Mg 2+ , Mn 2+ , Ni 2+ , Zn 2+ ) and nitro compound (o-chloronitrobenzene (CNB), o-nitrophenol (NP), 1,3-dinitrobenzene (DNB), m-nitrobenzene (NT), nitrobenzene (NB), 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), octogen (HMX), hexogen (RDX)) was prepared. Then, a 0.01 g / L polymer solution (THF / water = 1:9) was prepared in 500 mL. 10 mL of the polymer solution was placed in a glass bottle, and 20 μL of the prepared metal ion or nitro compound solution was added to each sample, respectively. After the fluorescence was stable, the fluorescence spectrum was measured under 365 nm UV excitation.

[0087] (10) Stability of polymer solution

[0088] Prepare 200 mL of a 0.01 g / L polymer solution (THF / H2O = 1:9). Take 20 mL of this solution every three days for particle size analysis and fluorescence spectroscopy determination, and continue for 21 days.

[0089] IV. Results and Discussion

[0090] 1. Characterization of monomers

[0091] The structure of TPATz-2OH was characterized by infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy. Figure 1 (a) shows the infrared spectrum of 4-hydroxybenzylamidinium hydrochloride, 4-diphenylaminobenzaldehyde, and TPATz-2OH. It can be seen that before and after the reaction, at 3300 cm⁻¹... -1 The broad peak belonging to 4-hydroxybenzylamine hydrochloride almost completely disappeared, and at 1688 cm⁻¹... -1 The characteristic peak of the C=O stretching vibration of 4-diphenylaminobenzaldehyde disappears at 815 cm⁻¹, while at 815 cm⁻¹... -1 The characteristic peak of the triazine CH bending vibration and 3400 cm⁻¹ -1 The appearance of the hydroxyl stretching vibration peak confirms the successful preparation of TPATz-2OH. The 1H NMR characterization of TPATz-2OH is as follows: Figure 1 In (b), the hydrogen atom elution positions of TPATz-2OH in the range of 6.5-9 ppm correspond one-to-one with its structure, which also confirms the successful synthesis of TPATz-2OH.

[0092] 2. Characterization of polymers

[0093] Both PTPATzS and PTPATzK are yellow powdery solids, and their structures have been characterized by infrared and nuclear magnetic resonance. Figure 2 (a) in the image shows the infrared spectrum of the polymer. In the PTPATzS spectrum, 1296 and 1146 cm⁻¹... -1 Characteristic peaks for both asymmetric and symmetric stretching vibrations of the sulfone group are observed, at 815 cm⁻¹. -1 The characteristic peak of triazine out-of-plane bending vibration appears at 1650 cm⁻¹; in the PTPATzK spectrum, the peak is at 1650 cm⁻¹. -1 The characteristic peak of carbonyl stretching vibration appears at 815 cm⁻¹. -1 The characteristic peak of the out-of-plane bending vibration of triazine appears at [location]. The 1H NMR spectra of PTPATzS and PTPATzK are as follows: Figure 2 As shown in (b) and (c), within the range of 6-9 ppm, the hydrogen atom peak positions correspond one-to-one with the polymer molecular structure. Furthermore, the hydroxyl NMR peaks at 10.5 ppm for PTPATzS and PTPATzK have disappeared, indicating that the hydroxyl groups in TPATz-2OH have completely reacted during the reaction. Infrared and NMR characterization results confirm the successful preparation of the polymer.

[0094] 3. Thermal stability of polymers

[0095] Figure 3 The TGA and DSC curves of polymers are shown in the figure. It can be seen from the figure that polytriphenylamine-triazine has excellent thermal stability. In the nitrogen atmosphere, there is almost no weight loss below 500℃. The temperature at which 5% weight loss occurs is 564℃ and 538℃, respectively, and the carbon residue rate is 57% and 50% when heated to 800℃, respectively. The excellent thermal stability of them is attributed to the strong polarity of the triazine group, which makes the polymer structure have strong rigidity. And the polymer prepared by C-O coupling has higher molecular weight, which can improve the thermal stability of the polymer. The DSC test results show that the glass transition temperature of PTPATAzS and PTPATzK is 220℃ and 197℃, respectively. The reason for the large difference in glass transition temperature may be that the polarity of the sulfone group is higher than that of the carbonyl group, making PTPATzS more rigid; at the same time, the sulfone group as a strong polar group has higher intermolecular interaction than the carbonyl group, such as the dipole-dipole interaction formed by the sulfone group-sulfone group, which will make the polymer with sulfone group have higher glass transition temperature.

[0096] 4. Study on the photophysical properties of polymers

[0097] Both PTPATzS and PTPATzK have triphenylamine-triazine structure, which can promote the generation of ICT effect, and the twisted structure of the main chain can effectively inhibit the fluorescence quenching phenomenon in the aggregate state, which is the prerequisite for the detection of TNT in water. The photophysical properties of the polymers were characterized, Figure 4 The UV-Vis absorption spectra, fluorescence spectra and fluorescence decay curves of PTPATzS and PTPATzK powders are shown. Because of the high similarity of their structures, PTPATzS and PTPATzK powders show similar UV absorption in the range of 200-500nm. Under ultraviolet light, PTPATzS shows strong green fluorescence, while PTPATzK shows strong blue-green fluorescence. Through fluorescence spectrum test, the maximum emission wavelength of PTPATzS and PTPATzK is 509nm and 499nm, respectively. The difference is due to the different effects of diphenyl sulfone and benzophenone structure on the electron distribution of triazine. It is worth noting that the small molecule TPATz-2OH with the same triphenylamine-triazine structure shows almost no fluorescence characteristics in the solid state, while PTPATzS and PTPATzK show high intensity fluorescence emission in the solid state, which also confirms the feasibility of the idea of inhibiting the accumulation of molecules in the solid state by twisting the polymer main chain.

[0098] As Figure 4PTPATzS and PTPATzK both have longer fluorescence lifetime, the two fluorescence lifetime τ1 and τ2 of PTPATzS are 1.9 ns and 4.9 ns, the two transition mode component ratio are 43.57% and 56.43%, the average fluorescence lifetime <τ>avg is 3.62 ns; the two fluorescence lifetime τ1 and τ2 of PTPATzK are 2.4 ns and 5.2 ns, the two transition mode component ratio are 50.37% and 49.63%, the average lifetime <τ>avg is 3.75 ns. PTPATzS and PTPATzK have higher fluorescence lifetime τ2 ratio, and the average fluorescence lifetime <τ>avg is larger, and longer fluorescence lifetime usually represents higher radiation transition ratio, which is the reason for high quantum yield (powder state, PTPATzS: PTPATzK: ).

[0099] Table 3 Quantum yield and fluorescence lifetime of polymer powder

[0100]

[0101] Note: In the table is the absolute quantum yield measured by integrating sphere of fluorescence spectrometer; τ1 and τ2 are the fluorescence lifetime of second-order exponential fitting; <τ>avg is the average fluorescence lifetime.

[0102] As Figure 5 shown, the ultraviolet-visible absorption spectrum and fluorescence spectrum of the polymer in n-hexane (HEX), trichloromethane (TCM), ethyl acetate (EA), dichloromethane (DCM), tetrahydrofuran (THF), N,N-dimethylformamide (DMF), ethanol (EtOH) and methanol (MeOH) were tested, and the photophysical parameters were summarized in Table 4. PTPATzS and PTPATzK both have two absorption peaks in the range of 300-500 nm, and their two absorption peaks are near 300 nm and 390 nm, which are the π-π* transition of benzene ring and the ICT absorption of triphenylamine-triazine structure in the polymer, respectively. In different polarity solvents, PTPATzS and PTPATzK both show a small amount of solvent discoloration. For example, the two absorption peaks of PTPATzS in low polarity solvent (HEX) are 304 nm and 403 nm, respectively; while in high polarity solvent (DMF), the wavelengths are 295 nm and 391 nm, respectively. In different polarity solvents, the two absorption peaks have a maximum shift of 9 nm and 12 nm.

[0103] Table 4 Photophysical properties of PTPATzS and PTPATzK in different solvents

[0104]

[0105] Note: Δf is the orientation polarizability of the solvent; λabsis the maximum absorption wavelength of the polymer solution; λemis the maximum emission wavelength of the polymer solution; Δν is the Stokes shift of the polymer solution; is the fluorescence quantum yield of the polymer solution.

[0106] In addition, PTPATzS and PTPATzK exhibit significant emission wavelength difference in different polarity solvents. In the low polarity solvent (HEX), the maximum emission wavelength of PTPATzS is 483 nm, while in the high polarity solvent (DMF), the value is 552 nm, with a maximum emission wavelength shift of 69 nm. PTPATzK shows a stronger solvent color change effect, with a maximum emission wavelength of 471 nm in the low polarity solvent (HEX), and a maximum emission wavelength of 548 nm in the high polarity solvent (DMF), with an emission wavelength shift of 74 nm. This is due to the presence of triphenylamine-triazine in the structure of PTPATzS and PTPATzK, which can achieve charge transfer (CT) from electron donor to electron acceptor in the excited state. The CT process significantly increases the dipole moment of the excited state, and the high polarity solvent has a more significant effect on the stability of the excited state with higher dipole moment, which can reduce the excited state energy to some extent, making the emission wavelength red shift.

[0107] Notably, the quantum yield in different solvents shows that the quantum yield of the two polymers in high polarity solvents is significantly lower than that in low and medium polarity solvents, due to the stronger solute-solvent interaction in high polarity solvents, which dissipates the excited state energy through non-radiative transition, weakening the fluorescence emission of the polymer. The orientation polarizability (Δf) is introduced as a physical parameter to describe the polarity of the solvent, and the Lippert-Mataga equation is used to further study the color change behavior caused by the polarity of the solvent. As shown in Figure 6 by linear fitting of the Δf of different solvents and the Stokes shift (Δν) of the polymer in the corresponding solvent, the results show that the linear relationship between Δν and Δf has poor fitting effect, but the overall trend is that the larger the polarity of the solvent, the larger the Stokes shift. These results show that the excited state of PTPATzS and PTPATzK in different solvents may exist simultaneously in the local excitation (LE) state and the intramolecular charge transfer (ICT) state. Under normal circumstances, the fluorescence emission in low polarity solvents is mainly due to the LE state, while in high polarity solvents, the polymer is more likely to form a stable twisted conformation, which promotes charge separation, significantly increasing the component of the ICT state.

[0108] The luminescence properties of PTPATzS and PTPATzK in dilute solutions and aggregated states were investigated in a binary solvent system (tetrahydrofuran / water). Figure 7 The PTPATzS and PTPATzK exhibit similar trends across different water contents. Within the 0-10% water content range, the polymer fluorescence significantly decreases with increasing water content, while the maximum emission wavelength exhibits a significant redshift. This is because the addition of trace amounts of water to the tetrahydrofuran solution increases the solution's polarity, inducing molecules to enter a twisted intramolecular charge transfer (TICT) state—a specific ICT effect. When the two planar DA structures of a molecule are connected by a single bond, electrons are excited and enter the TICT state. Excited molecules in this state typically return to the ground state via a non-radiative transition involving single-bond rotation. Within the 10%-60% water content range, polymer nanoparticles gradually form in the solution, and the polymer transitions from solution luminescence to aggregate luminescence. The twisted structure of the polymer backbone effectively suppresses the stacking of polymer chains, leading to a gradual increase in fluorescence within this water content range. Within the water content range of 60%-99%, as the water content increases, the polymer particles in the solution aggregate to a greater extent, leading to a gradual decrease in fluorescence. The quantum yields of PTPATzS and PTPATzK aggregates in water were tested. They can still reach 0.35 and 0.57.

[0109] 5. Detection of TNT by Polymers

[0110] The concentration of TNT in the solution was gradually increased, and the change in fluorescence intensity of the polymer solution was measured. The Stern-Volmer equation was used for fitting analysis. The response of TNT was as follows: Figure 8 As shown in (a) and (c), the fluorescence intensity of the polymer solution gradually decreased with increasing TNT concentration. When the TNT concentration was 0.22 μM, the fluorescence intensity of the PTPATzS solution was quenched by 12%; when the TNT concentration was 2.2 μM, the fluorescence intensity was quenched by 83%. PTPATzK showed slightly less effective detection of TNT than PTPATzS; when the TNT concentration was 0.44 μM, the fluorescence intensity of the PTPATzK solution was quenched by 14%; when the TNT concentration was 8.8 μM, the fluorescence intensity was quenched by 78%. The Stern-Volmer equation fitting curves (…) Figure 8As can be seen from Figs. 8 (b) and (d)), the ratio of initial fluorescence intensity to quenched fluorescence intensity (I0 / I) of PTPATzS and PTPATzK showed a strong linear correlation with the concentration of TNT (cTNT) when the concentration of TNT was below 1.1 μM and 8.8 μM, respectively. When the concentration of TNT was higher than 1.1 μM and 8.8 μM, respectively, the relationship between I0 / I and cTNT gradually deviated from linearity. Similarly, PTPATzS and PTPATzK showed a strong linear correlation with the concentration of TNT (cTNT) when the concentration of TNT was below 1.1 μM and 8.8 μM, respectively. When the concentration of TNT was higher than 1.1 μM and 8.8 μM, respectively, the relationship between I0 / I and cTNT gradually deviated from linearity. The Stern-Volmer constants (KSV) of PTPATzS and PTPATzK were calculated to be as high as 6.97 x 10 5 M -1 and 3.88 x 10 5 M -1 , with a detection limit (LOD) as low as 39 nM and 70 nM, which outperformed most of the reported TNT fluorescent probes (Table 5). As shown in Fig. 9, both PTPATzS and PTPATzK exhibited ultrafast response speed to TNT added to the polymer solution, which could complete the response to TNT within 15 s without continuous shaking. Figure 9

[0111] Table 5 Performance comparison of PTPAS with reported TNT probes

[0112]

[0113] [1] Xu YW, Zhong C, Zhang BY, et al. Facile preparation of tetraphenylethylene-based porous polymer with dual role of adsorption and detection for trinitrotoluene [J]. Polymer, 2023, 288: 126454.

[0114] ​[2]Mukherjee A, Bhattacharya S, Chakravarty M. An unprecedented pyridine-based dinuclear mixed-valent Rel / VII oxo-bridged complex: asolvatochromic and AIE-active probe for nanomolar detection of picric acid and trinitrotoluene [J]. Dalton Transactions, 2021, 50(26): 9144-9157.

[0115] [3]Liao Y, Hu L, Huang J, et al. A facile and novel AIE vesicle as nanoprobe for simple and rapid detection of TNT in water [J]. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2024, 307: 123617.

[0116] [4]Dong W, Fei T, Scherf U. Conjugated polymers containing tetraphenylethylene in the backbones and side-chains for highly sensitive TNT detection [J]. RSC Advances, 2018, 8(11): 5760-5767.

[0117] [5]Dong W, Ma Z, Chen P, et al. Carbazole and tetraphenylethylene based AIE-active conjugated polymer for highly sensitive TNT detection [J]. Materials Letters, 2019, 236: 480-482.

[0118] [6] Komikawa T, Tanaka M, Tamang A, et al. Peptide-functionalized quantum dots for rapid label-free sensing of 2, 4, 6-trinitrotoluene [J]. Bioconjugate Chemistry, 2020, 31(5): 1400-1407.

[0119] [7] SK. Pyrene substituted amphiphilic ROMP polymers as nano-sized fluorescence sensors for detection of TNT in water [J]. Polymer, 2019, 183: 121868.

[0120] [8] Doan BK, Tran TVT, Nguyen TH, et al. One-pot synthesis of star-shaped conjugated oligomers based on 3-hexylthiophene, pyrene and triphenylamine as TNT chemosensors [J]. Journal of Photochemistry and Photobiology A: Chemistry, 2020, 394: 112496.

[0121] In addition, PTPATzS and PTPATzK have good fluorescence quenching properties for salbutamol sulfate solution.

[0122] 6. The influence of pH on the properties of polymers

[0123] The influence of pH on the fluorescence properties and detection performance of PTPATzS and PTPATzK solutions was studied. Figure 10 (a) in Figure 1 shows that PTPATzS exhibits small fluorescence changes in the pH range of 2-8, while the fluorescence intensity is severely weakened at pH < 2 and pH > 8. Fortunately, even if the fluorescence properties of PTPATzS are affected by strong acid and strong base, the detection process is not affected. PTPATzK also exhibits similar phenomena (b) in Figure 1), the fluorescence is less affected by pH in the pH range of 3-9, while the fluorescence properties are greatly affected by pH at pH < 2 and pH > 9, and again, the detection process is not affected by pH. Figure 10 (a) in Figure 1 shows that PTPATzS exhibits small fluorescence changes in the pH range of 2-8, while the fluorescence intensity is severely weakened at pH < 2 and pH > 8. Fortunately, even if the fluorescence properties of PTPATzS are affected by strong acid and strong base, the detection process is not affected. PTPATzK also exhibits similar phenomena (b) in Figure 1), the fluorescence is less affected by pH in the pH range of 3-9, while the fluorescence properties are greatly affected by pH at pH < 2 and pH > 9, and again, the detection process is not affected by pH.

[0124] PTPATzS and PTPATzK are more sensitive to the pH value of the solution, which may be due to the increase of the polarity of the solvent under strong acid or strong base conditions. Both PTPATzS and PTPATzK have strong TICT effect, and the side group triphenylamine can dissipate energy in the form of non-radiative transition by single bond rotation in the excited state after the polarity is enhanced, resulting in a decrease in fluorescence intensity. The detection of TNT is almost not affected by the pH value, which may be due to the fact that the triphenylamine structure is stable enough under acidic and basic conditions, while the electron-deficient property of TNT tends to form interaction with the electron-rich triphenylamine group, and this quenching channel is not affected under acidic or basic conditions. In addition, the fluorescence is not completely quenched after adding TNT under the condition of pH = 12, which may be due to the fact that TNT will form J-aggregates under alkaline conditions. The formation of this dimer will increase the steric hindrance effect when interacting with triphenylamine, and at the same time, this process will also reduce the concentration of TNT in the solution.

[0125] 7. Selectivity of polymers to TNT

[0126] Different nitro compounds (CNB, DNB, DNT, HMX, NB, NP, NT, RDX), metal ions (Ag + , Al 3+ , Ca 2+ , Co 3+ , Cu 2+ , Fe 2+ , Fe 3+ , Mg 2+ , Mn 2+ , Ni 2+ , Zn 2+ ) and anions (F - , Cl - , Br - , I - , SO4 2- , SO3 2- , CO3 2- , PO4 3- , HPO4 2- , AcO - , NO3 - ) and other potential interferents that may affect the fluorescence of the polymers were added to the solutions of PTPATzS and PTPATzK to investigate the selectivity of the materials to TNT. As shown in FIGS. 1-3, the fluorescence of PTPATzS and PTPATzK is hardly affected by common nitro compounds, metal ions and anions, but shows a significant quenching response to TNT. Figure 11 , Figure 12 and Figure 13

[0127] ​8. Stability of polymer solution

[0128] The stability and shelf life of the polymer solution were evaluated by monitoring the change of particle size and fluorescence properties within 21 days. As shown in Fig. 8, the fluorescence intensity and the average particle size of the polymer solution changed little within 21 days, which indicated that the polymer solution had a long shelf life. Figure 14

[0129] 9. Conclusion

[0130] Firstly, a triphenylamine-triazine monomer TPATz-2OH was successfully synthesized, which showed high fluorescence intensity in solution and almost no fluorescence properties in aggregation state. Based on this monomer, two polymers PTPATzS and PTPATzK were successfully prepared by C-O coupling reaction. The twisted structure of the polymer main chain made them show high quantum yield in solution (in chloroform, PTPATzS: PTPATzK: ) and solid state (PTPATzS: PTPATzK, ). PTPATzS and PTPATzK not only had good fluorescence quenching properties for salbutamol sulfate solution, but also showed high sensitivity to TNT, with Stern-Volmer constants (KSV) of 6.97 x 10 5 M -1 and 3.88 x 10 5 M -1 , and detection limits (LOD) as low as 39 nM and 70 nM. At the same time, PTPATzS and PTPATzK could complete the response to TNT within 15 s. In addition, PTPATzS and PTPATzK had good anti-interference ability for the detection of salbutamol sulfate solution and TNT.​

Claims

1. A compound of triphenylamine-triazine structure, characterized by, The compound of the triphenylamine-triazine structure has the following formula :

2. Process for the preparation of the compound of triphenylamine-triazine structure according to claim 1, characterized in that, The compound is prepared by adding dimethyl sulfoxide dropwise into a mixture containing 4-hydroxybenzamidine hydrochloride, 4-diphenylamino benzaldehyde and cesium carbonate, and then performing a warming reaction, precipitating the product and performing multiple extractions to obtain a crude product, and then purifying the crude product by column chromatography.

3. The production method according to claim 2, characterized by, The molar ratio of the 4-hydroxybenzamidine hydrochloride, 4-diphenylamino benzaldehyde and cesium carbonate is 2-2.5:1-1.2:2-2.

5.

4. The production method according to claim 2, characterized by, The reaction temperature is 120-140 DEG C, and the reaction time is 16-20 hours.

5. The preparation method according to claim 2, characterized in that, The column chromatography uses ethyl acetate and petroleum ether as developing agents, and the volume ratio is 1:

2.

6. A D-A type polytriphenylamine triazine compound, characterized by, The D-A type polytriphenylamine triazine compound has the following formula <II>: ； The X is --SO2-- or --CO--.

7. The D-A polytriphenylamine triazine compound according to claim 6, characterized in that, The average lifetime <τ>avg of the D-A type polytriphenylamine triazine compound is 3.62-3.75 ns, and the fluorescence quantum yield φF in water is 0.39-0.

53.

8. The D-A polytriphenylamine triazine compound according to claim 6, characterized in that, The thermal decomposition temperature of the D-A type polytriphenylamine triazine compound is 538-564 DEG C, and the glass transition temperature is 197-220 DEG C.

9. The D-A polytriphenylamine triazine compound according to claim 6, characterized in that, The D-A type polytriphenylamine triazine compound has a fluorescence quenching response to a drug salbutamol sulfate solution, and the detection limit of TNT in water is 39-70 nM.

10. The method of producing a D-A type polytriphenylamine triazine compound according to any one of claims 6 to 9, wherein The compound is prepared by a one-step C-O coupling reaction of 4,4'-difluorodiphenyl sulfone or 4,4'-difluorobenzophenone, a compound of the triphenylamine-triazine structure and potassium carbonate under a nitrogen atmosphere. The compound of the triphenylamine-triazine structure has the following formula :

11. The method of claim 10, wherein, The molar ratio of the 4,4'-difluorodiphenyl sulfone or 4,4'-difluorobenzophenone, the compound of the triphenylamine-triazine structure and potassium carbonate is 1-1.2:1-1.2:1.5-2.

0.

12. The method of claim 10, wherein, The reaction temperature of the C-O coupling reaction is 150-180 DEG C, and the reaction time is 6-12 hours.

13. The use of the D-A type polytriphenylamine triazine compound of any one of claims 6-9 and the D-A type polytriphenylamine triazine compound prepared by the method of any one of claims 10-12 as a fluorescence probe for detecting the content of TNT in water and detecting salbutamol sulfate products.

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