A dehydroabietic acid-based aggregation-induced emission (AIE) and excited state intramolecular proton transfer (ESIPT) dual-property compound, a preparation method therefor, and applications thereof

Abstract

The application discloses a dehydroabietic acid-based aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) dual-property compound, a preparation method and application thereof. The structural formula of the dehydroabietic acid-based aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) dual-property compound is as follows: the dehydroabietic acid-based aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) dual-property compound is prepared from the reaction of 12-[N,N-p-methoxy-4-boronate phenyl] amido-dehydroabietic acid methyl ester and 2-(benzo[d]thiazole-2-yl)-4-bromophenol. The dehydroabietic acid-based aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) dual-property compound DTPA-HBT has a large Stokes shift, can be used for fluorescence imaging, and can also be applied to fluorescence anti-counterfeiting; and the synthetic route is mild, controllable and easy to operate.

Description

Technical Field

[0001] This invention relates to a compound with dual characteristics of dehydroabsic acid-based aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT), its preparation method, and its applications, belonging to the fields of organic fluorescent molecule synthesis and functional materials technology. Background Technology

[0002] Traditional organic fluorescent dyes often exhibit aggregation-induced quenching (ACQ) in the aggregated state, which limits their practical applications. Aggregation-induced emission (AIE) fundamentally solves this problem.

[0003] Excited-state intramolecular proton transfer (ESIPT) refers to the proton transfer process that occurs between adjacent proton donors and proton acceptors within a molecule when the molecule is photoexcited, due to enhanced hydrogen bonding. ESIPT molecules in the excited state can achieve a structural transformation through intramolecular proton transfer, resulting in a large Stokes shift, which leads to a significant change in fluorescence wavelength, exhibiting different luminescence states, and effectively avoiding self-absorption.

[0004] Combining ESIPT and AIE properties offers new possibilities for developing novel luminescent materials. However, the variety of fluorescent molecules with both ESIPT and AIE effects currently developed is very limited. In particular, molecules based on disproportionated rosin that possess both ESIPT and AIE properties are limited to a few simple Schiff base compounds with limited structural diversity and a handful of known examples. Furthermore, their quantum yields in the solid state are low (<4%), some even as low as 0.3%. Moreover, these compounds are of limited variety, have short emission wavelengths, and limited Stokes shifts, rarely exhibiting synergistic effects between AIE and ESIPT.

[0005] Dehydroabietic acid is obtained from rosin through catalytic disproportionation and purification. Its skeleton contains an aromatic ring, and various fluorescent derivatives can be developed based on the aromatic ring and carboxylic acid group, opening up new avenues for the high-value utilization of rosin. However, its ACQ effect and relatively short emission wavelength limit its applications. To address this problem, this invention combines the dehydroabietic acid derivative with 2-(2-hydroxyphenyl)benzothiazole, and through specific structural design, not only does it achieve a large Stokes shift, but it also extends the emission of the dehydroabietic acid derivative from high-energy blue light to low-energy orange light, exhibiting a significant synergistic effect between AIE and ESIPT. Summary of the Invention

[0006] This invention provides a compound with dual characteristics of aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) of dehydroabsic acid group, its preparation method and its application. The compound has aggregation-induced emission enhancement and excited-state intramolecular proton transfer characteristics, and has a large Stokes shift. It can be used for fluorescence imaging and also for fluorescence anti-counterfeiting.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A compound exhibiting both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) properties, specifically a dehydroabsic acid-based compound, possesses both enhanced aggregation-induced emission and excited-state intramolecular proton transfer effects. The structural formula of this compound is as follows:

[0009]

[0010] The aforementioned compound exhibiting both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics, named DTPA-HBT, demonstrates dual properties. The hydroxyl group (-OH) acts as a proton donor, and the nitrogen atom (N) on the thiazole ring acts as a proton acceptor. Effective intramolecular hydrogen bonding facilitates the excited-state proton transfer process, exhibiting ESIPT characteristics. In the aggregated state, the π-π stacking of the molecule is hindered, resulting in enhanced fluorescence emission and a pronounced AIE characteristic. These two properties exhibit a significant synergistic effect. On one hand, in the biocompatible organic solvents DMSO and ethanol / water (v:v=3 / 7), the fluorescence quantum yield is 3.28 and 1.24 times that of the solid-state quantum yield, respectively. On the other hand, the Stokes shift reaches 280 nm, effectively avoiding self-absorption and internal filtration effects, which is beneficial for fluorescence imaging and can be used as an AIE probe for cell imaging. Simultaneously, it possesses the potential of an invisible ink, suitable for fluorescent anti-counterfeiting applications, exhibiting durability and stability, effectively extending the anti-counterfeiting period.

[0011] The synthetic route for the above-mentioned compounds exhibiting both dehydroabsic acid aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) dual properties is as follows:

[0012]

[0013] The preparation method of the above-mentioned compound with dual characteristics of aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) of dehydroabsic acid group is as follows: Under nitrogen protection, methyl 12-[N,N-p-methoxy-4-boronate phenyl]amino-dehydroabsic acid and 2-(benzo[d]thiazol-2-yl)-4-bromophenol are used as raw materials, potassium carbonate and tetra(triphenylphosphine)palladium are added, and Suzuki coupling reaction is carried out in tetrahydrofuran / water system. After the reaction is completed, the mixture is cooled and purified to obtain compound DTPA-HBT.

[0014] To ensure product purity, purification was performed as follows: After cooling, the product was sequentially extracted with dichloromethane and water, the organic phase was collected, dried with anhydrous magnesium sulfate, purified by column chromatography, rotary evaporation, and dried to obtain the AIE / ESIPT dual-characteristic compound DTPA-HBT. The preferred eluent for column chromatography purification was a mixture of petroleum ether and ethyl acetate in a volume ratio of (24-26):1.

[0015] To improve product yield, the molar ratio of methyl 12-[N,N-p-methoxy-4-boronatephenyl]amino-dehydroabenzyl ester to 2-(benzo[d]thiazol-2-yl)-4-bromophenol is 1:(1 to 1.1), more preferably 1:1.1.

[0016] To further improve the product yield, the molar ratio of 2-(benzo[d]thiazolyl)-4-bromophenol, potassium carbonate, and tetra(triphenylphosphine)palladium is (1-1.1):(1-1.2):(0.02-0.03), more preferably 1.1:1.2:0.03.

[0017] To improve reaction efficiency, the solvent used was a mixed solution of tetrahydrofuran and water, the reaction temperature was 35–45°C, and the reaction time was 36–48 h.

[0018] The above-mentioned methyl 12-[N,N-p-methoxy-4-boronate phenyl]amino-dehydroabirate can be prepared by the following method: methyl 12-[N,N-p-methoxy-4-bromophenyl]amino-dehydroabirate and bis(pinacolyl)diboron are dissolved in dimethyl sulfoxide, protected by nitrogen gas, and potassium acetate and [1,1′-bis(diphenylphosphine)ferrocene]palladium(II)dichloromethane complex are added. The reaction is carried out at 70-80°C for 20-24 h, cooled, extracted with dichloromethane and water, and the organic phase is collected, dried over anhydrous magnesium sulfate, purified by column chromatography, the solvent is removed by rotary evaporation, and dried under vacuum to obtain a white solid methyl 12-[N,N-p-methoxy-4-boronate phenyl]amino-dehydroabirate.

[0019] The molar ratio of the above-mentioned methyl 12-[N,N-p-methoxy-4-bromophenyl]amino-dehydroabenic acid, bis(pinacolyl)diboron, potassium acetate, and [1,1′-bis(diphenylphosphine)ferrocene]palladium(II)dichloromethane complex is 1:(1.8-2):(3.5-4):(0.04-0.06).

[0020] The above-mentioned methyl 12-[N,N-p-methoxy-4-bromophenyl]amino-dehydroabirate can be prepared by the following method: methyl 12-[N,N-(4-methoxy)-phenyl]amino-dehydroabirate (DTPA), NBS (N-bromosuccinimide), and anhydrous acetonitrile are added to a round-bottom flask and reacted in the dark at 20–25°C for 18–24 h. The mixture is then rotary evaporated, purified, and dried to obtain a white solid, methyl 12-[N,N-(4-methoxy)-(4-bromophenyl)]amino-dehydroabirate (DTPA-Br), which is stored in a desiccator for later use. The molar ratio of methyl 12-[N,N-(4-methoxy)-phenyl]amino-dehydroabirate (DTPA) to NBS (N-bromosuccinimide) is 1:(1–1.1).

[0021] The above-mentioned methyl 12-[N,N-(4-methoxy)-phenyl]amino-dehydroabirate (DTPA) can be prepared by the following method: methyl 12-(phenyl)amino-dehydroabirate (DDPA) and p-bromoanisole are added to a three-necked flask, anhydrous o-xylene is added, nitrogen is purged, sodium tert-butoxide, tri-tert-butylphosphine and palladium acetate are added, and the mixture is heated under reflux for 8-12 h. The mixture is extracted with diethyl ether and water, the organic phase is collected, dried over anhydrous magnesium sulfate, purified by column chromatography, and the solvent is removed by rotary evaporation. The mixture is then placed in a vacuum drying oven at 60-65℃ and dried under vacuum for 10-12 h to obtain a light yellow solid, methyl 12-[N,N-(4-methoxy)-phenyl]amino-dehydroabirate (DTPA), which is stored in a desiccator for later use. The molar ratio of methyl 12-(phenyl)amino-dehydroabscisic acid (DDPA), p-bromoanisole, sodium tert-butoxide, tri-tert-butylphosphine and palladium acetate is 1:(1.1~1.2):(1.41~1.45):(0.10~0.12):(0.01~0.03).

[0022] The above-mentioned 2-(benzo[d]thiazol-2-yl)-4-bromophenol can be prepared by the following method: 5-bromosalicylic acid and o-aminothiophenol are dissolved in water, aminosulfonic acid is added, and the mixture is stirred at room temperature for 0.5 to 1 h. The mixture is filtered and washed with water to obtain a crude product, which is then recrystallized from a water-ethanol mixed solvent to obtain a yellow solid 2-(benzo[d]thiazol-2-yl)-4-bromophenol.

[0023] The molar ratio of 5-bromosalicylaldehyde, o-aminothiophenol, and aminosulfonic acid is 1:(1-1.1):(0.03-0.04).

[0024] Any techniques not mentioned in this invention are based on existing technologies.

[0025] Beneficial effects

[0026] (1) Starting from dehydroabsic acid derivatives, this invention synthesizes a compound with a novel structure that combines the properties of both AIE and ESIPT, exhibiting a significant synergistic effect between AIE and ESIPT. The synthetic route is mild, controllable and easy to operate.

[0027] (2) The compound DTPA-HBT, which has dual characteristics of dehydroabsic acid aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT), provided by the present invention has a fluorescence quantum yield 1 to 4 times higher than that of solid-state fluorescence in a relatively mild and biocompatible organic solvent (DMSO or ethanol / water mixed solution), and the maximum Stokes shift can reach 280 nm. It can effectively avoid or reduce background interference and self-absorption, reduce phototoxicity, enhance tissue penetration depth, improve display quality, and facilitate cell imaging, etc.

[0028] (3) The dehydroabsic acid-based aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) dual-characteristic compound DTPA-HBT provided by the present invention has obvious aggregation-induced emission enhancement properties, and has the characteristics of dual and triple emission. In the excited state, it has a more three-dimensional configuration and a plane that is conducive to proton transfer, which is beneficial to AIE and ESIPT properties. Attached Figure Description

[0029] Figure 1 The DTPA-HBT of this invention 1 H NMR spectrum;

[0030] Figure 2 The DTPA-HBT of this invention 13 C NMR spectrum;

[0031] Figure 3 This is the high-resolution mass spectrometry (HRMS) image of the DTPA-HBT of this invention;

[0032] Figure 4 The UV absorption spectra of DTPA-HBT in different solutions of the present invention (1×10⁻⁶) -5 mol / L);

[0033] Figure 5 The fluorescence emission spectra of DTPA-HBT in different solutions of the present invention (1×10⁻⁶) -5 (mol / L), with an excitation wavelength of 340 nm;

[0034] Figure 6The present invention provides DTPA-HBT for different water volume fractions (f w Fluorescence emission spectrum of ethanol / water mixed solvent (1×10) -5 mol / L), the insets are f w =0% and f w Photograph of a 70% DTPA-HBT solution under 365nm UV irradiation;

[0035] Figure 7 This is a graph showing the relationship between the fluorescence intensity I / I0 of DTPA-HBT and the water content (I0 is the concentration of the compound at f). w = 0% fluorescence emission intensity in solution, where I is the fluorescence emission intensity of the compound at the corresponding f w =Fluorescence emission intensity at 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 99%);

[0036] Figure 8 This is a graph showing the relationship between the DTPA-HBT nanoparticle size (DLS) of this invention and different water contents;

[0037] Figure 9 For the present invention DTPA-HBT in f w =0% and f w Photographs of the Tyndall effect at 70%;

[0038] Figure 10 The diagram shows the optimized structure of the DTPA-HBT in the ground state (S0) and excited state (S1) calculated by density functional theory and time-dependent density functional theory methods.

[0039] Figure 11 The diagram shows the lowest unoccupied orbital (LUMO) and highest occupied orbital (HOMO) energy levels of the DTPA-HBT of the present invention in the ground state (S0) and excited state (S1);

[0040] Figure 12 This is a dihedral diagram of the DTPA-HBT of the present invention in the ground state (S0) and excited state (S1);

[0041] Figure 13 This is a planarity analysis diagram of the DTPA-HBT of the present invention in the ground state (S0) and excited state (S1);

[0042] Figure 14 This is a diagram illustrating the four-level energy level mechanism of the DTPA-HBT enol and keto tautomerism caused by intramolecular proton transfer in the excited state, as described in this invention.

[0043] Figure 15 This is a fluorescent anti-counterfeiting effect diagram of the DTPA-HBT solution of the present invention.

[0044] Figure 16 This is a diagram showing the effect of the DTPA-HBT fluorescent anti-counterfeiting device of the present invention under 365nm ultraviolet light irradiation after 72 days. Detailed Implementation

[0045] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0046] Example 1

[0047] A compound exhibiting both dehydroabsic acid aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics is synthesized via the following route:

[0048]

[0049] The preparation process is as follows:

[0050] 1 mmol of methyl 12-bromodehydroabirate (DA) (Tan Guanni, et al. Synthesis and Spectroscopic Properties of Triarylamine Compounds Containing Bisnaphthyl Dehydroabirate [J]. Chemistry and Industry of Forest Products, 2019, 39(1): 61-66.) and 1.2 mmol of aniline were dissolved in 10 mL of anhydrous o-xylene. After deoxygenation under a nitrogen atmosphere for 15 minutes, 1.44 mmol of sodium tert-butoxide (t-BuONa), 0.12 mmol of tritert-butylphosphine (P(t-Bu)3), and 0.03 mmol of palladium acetate (Pd(OAc)2) were added. The mixture was heated to reflux at 140 °C for 12 h, cooled, extracted with diethyl ether and saturated brine, and the organic phase was collected, dried over anhydrous magnesium sulfate, and purified by column chromatography (eluent, V 石油醚 V 乙酸乙酯 =10:1), after removing the solvent by rotary evaporation, the mixture was placed in a vacuum drying oven at 65°C for 12 hours to obtain a light yellow solid methyl 12-(phenyl)amino-dehydroabietic acid (DDPA), which was then stored in a desiccator for later use.

[0051] 1 mmol of methyl 12-(phenyl)amino-dehydroabietic acid (DDPA) and 1.2 mmol of p-bromoanisole were added to a three-necked flask, followed by 10 mL of anhydrous o-xylene. Under nitrogen protection, 1.44 mmol of sodium tert-butoxide, 0.12 mmol of tri-tert-butylphosphine, and 0.03 mmol of palladium acetate were added. The mixture was heated to reflux for 12 h, extracted with ether and water, and the organic phase was collected, dried over anhydrous magnesium sulfate, and purified by column chromatography (eluent: V). 石油醚 V 乙酸乙酯=25:1), after removing the solvent by rotary evaporation, the mixture was placed in a vacuum drying oven at 65°C for 12 hours to obtain a light yellow solid methyl 12-[N,N-(4-methoxy)-phenyl]amino-dehydroabietic acid (DTPA), which was stored in a desiccator for later use.

[0052] 1 mmol of methyl 12-[N,N-(4-methoxy)-phenyl]amino-dehydroabietic acid (DTPA), 1 mmol of NBS (N-bromosuccinimide), and 25 mL of anhydrous acetonitrile were added to a round-bottom flask. The mixture was reacted at 25 °C in the dark for 24 h. The mixture was then purified by rotary evaporation and column chromatography (eluent: V). 石油醚 V 乙酸乙酯 =20:1), after removing the solvent by rotary evaporation, the mixture was placed in a vacuum drying oven at 65°C for 12 hours to obtain a white solid methyl 12-[N,N-(4-methoxy)-(4-bromophenyl)]amino-dehydroabietic acid (DTPA-Br), which was stored in a desiccator for later use.

[0053] 1 mmol of methyl 12-[N,N-p-methoxy-4-bromophenyl]amino-dehydroabirate (DTPA-Br) was added to a solution of 2 mmol bis(pinacol)diboron, 0.06 mmol Pd(dppf)Cl2·CH2Cl2, and 4 mmol potassium acetate in DMSO (15 mL). The mixture was stirred at 80 °C for 24 h under nitrogen. The mixture was extracted with dichloromethane and water, and the organic phase was collected, dried over anhydrous magnesium sulfate, and purified by column chromatography (eluent: V). 石油醚 V 乙酸乙酯 =20:1), the solvent was removed by rotary evaporation, and the product was dried under vacuum to give a white solid methyl 12-[N,N-p-methoxy-4-boronate phenyl]amino-dehydroabietic acid (DTPA-Bpin) in a yield of 73.1%.

[0054] 1 mmol of 5-bromosalicylic acid and 1 mmol of o-aminothiophenol were dissolved in 5 mL of water, and 0.04 mmol of aminosulfonic acid was added. The mixture was stirred at room temperature for 1 h, filtered, and washed with water. The solid was recrystallized from water or a water-ethanol mixture to give a yellow solid 2-(benzo[d]thiazol-2-yl)-4-bromophenol (HBT-Br). This step is a green synthesis method with a yield of 99.9%.

[0055] 1 mmol of methyl 12-[N,N-p-methoxy-4-boronate phenyl]amino-dehydroabirate (DTPA-Bpin), 1.1 mmol of 2-(benzo[d]thiazolyl-2-yl)-4-bromophenol (HBT-Br), and 1.2 mmol of potassium carbonate (K₂CO₃) were dissolved in a mixture of 20 mL of tetrahydrofuran and 5 mL of water. Under a nitrogen atmosphere, 0.03 mmol of tetra(triphenylphosphine)palladium was added, and the mixture was heated to reflux at 45 °C for 48 h. After cooling, the mixture was extracted with dichloromethane and water, and the organic phase was collected, dried over anhydrous magnesium sulfate, and purified by column chromatography (eluent: V). 石油醚 V 乙酸乙酯 After removing the solvent by rotary evaporation (v:v = 25:1), the solution was dried under vacuum at 60°C for 12 hours to obtain a yellow solid DTPA-HBT with a yield of 51.3%. The solid quantum yield of the yellow solid DTPA-HBT was 7.80%; the quantum yield in pure ethanol solution was 1.96%, the quantum yield in ethanol / water (v:v = 3 / 7) mixed solution was 9.71%, and the quantum yield in DMSO was 25.62%. The quantum yields in different solvents were all within the range of 10% at a concentration of 10%. -6 Measured under conditions of mol / L.

[0056] like Figures 1-3 As shown, the characterization data is as follows: 1 H NMR (500MHz, DMSO-d6) δ11.54(s,1H),8.34(s,1H),8.14(d,J=8.0Hz,1H),8.07(d,J=8.2Hz,1H),7.63(d,J=8.7Hz,1H),7.54(t,J=7.7Hz, 1H),7.46(dd,J=20.1,8.2Hz,3H),7.13(d,J=8.5Hz,1H),7.06(s,1H),7.00(d,J=6.9Hz,3H),6.89(d,J=9.0Hz,2H),6.78(d,J=8.7Hz,2H) ,3.73(s,3H),3.62(s,3H),3.04(p,J=6.8Hz,1H),2.91(dd,J=17.8,6.8Hz,1H),2.81(q,J=8.4,7.8Hz,1H),2.09(dd,J=24.8,12.1Hz,2H) ,1.86-1.75(m,1H),1.66(d,J=9.6Hz,2H),1.58-1.54(m,1H),1.33(s,1H),1.25(d,J=3.1Hz,2H),1.19(s,3H),1.13(s,3H),0.96(s,6H). 13C NMR (126MHz, DMSO-d6) δ177.93,164.74,155.07,154.83,151.42,148.57,147.65,145.60,143.56,141.01, 139.81,134.51,133.30,131.75,130.15,130.05,127.56,126.70,126.38,125.25,124.99,124.52,122.13 ,121.92,118.71,118.15,117.46,114.58,55.16,51.83,46.88,44.53,40.02,39.85,39.69,39.35,39.19, 39.02,37.57,36.47,36.11,29.20,26.80,24.80,23.38,23.29,21.03,17.83,16.21.HRMS(ESI):calc.for C 47 H 48 N₂O₄S, [M+H] + :737.3335; found,737.34094.

[0057] like Figures 4-5 As shown, the maximum absorption wavelength of DTPA-HBT, a compound exhibiting both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics, is around 320 nm in different solvents. However, its fluorescence emission spectrum varies considerably, with double or triple fluorescence peaks and a large Stokes shift caused by proton transfer, reflecting the molecule's ESIPT properties. The maximum Stokes shift reaches 280 nm. The short-wavelength emission near 410 nm is attributed to the enol form, the long-wavelength emission near 580 nm to the fluorescence emission of the keto isomer, and the emission peak near 520 nm is the intermediate state emission formed by the interaction between the molecule and the solvent.

[0058] like Figures 6-7 As shown, DTPA-HBT exhibits a typical aggregation-induced emission enhancement (AIE) effect, meaning its fluorescence emission intensity increases with increasing water content. When the water content is less than 50%, enol fluorescence emission is dominant at 415 nm. When the water content is greater than 60%, molecular aggregation restricts molecular motion, and the ESIPT effect is activated, resulting in a keto fluorescence emission peak at 585 nm. This indicates that molecular aggregation favors the proton transfer process, and stronger keto fluorescence emission caused by proton transfer indicates enhanced AIE properties. The overall spectral behavior demonstrates a clear synergistic effect between AIE and ESIPT properties.

[0059] like Figure 8 As shown, the change in aggregate size with increasing water content indicates that the aggregation state of DTPA-HBT is constantly changing.

[0060] like Figure 9 As shown, water content f w The Tyndall effect at 70% indicates that DTPA-HBT forms aggregates.

[0061] like Figure 10 As shown, the molecular configuration of DTPA-HBT is torn after being excited.

[0062] like Figure 11 As shown, proton transfer is often accompanied by electronic transitions. The band gap of a molecule is related to its chemical reactivity and kinetic stability. The band gap of DTPA-HBT in the excited state is 2.39 eV, which is smaller than the band gap of 3.07 eV in the ground state. This indicates that the molecule is more likely to undergo electronic transitions in the excited state, which is conducive to the proton transfer process.

[0063] like Figure 12 As shown, the dihedral angle between planes 5 and 6, which are related to intramolecular hydrogen bonds, decreases from 0.35° in the ground state to 0.31° in the excited state. This indicates that the planarity between planes 5 and 6 is better in the excited state, which is more conducive to proton transfer and ESIPT properties.

[0064] like Figure 13 As shown, the planarity of a molecule is characterized by the molecular planarity parameter (MPP) and the deviation from the plane span (SDP). The smaller the value, the better the planarity. In the ground state, both MPP and SDP values ​​are smaller than those in the excited state, indicating that the configuration in the excited state is more tortuous. The tortuous spatial configuration suppresses the close π-π packing and nonradiative transitions in the aggregated state, and is also more conducive to AIE properties.

[0065] like Figure 14 As shown, the four-level energy diagram of the DTPA-HBT molecule reveals the mechanism of enol and keto tautomerism.

[0066] Application Example 1

[0067] Take 7.36 mg of DTPA-HBT and place it in a 10 ml volumetric flask. Dilute to volume with dichloromethane to prepare a solution with a concentration of 1 × 10⁻⁶ mg / mL. -3 The stock solution was prepared at a concentration of 1 mol / L. 1000 μL of the stock solution was pipetted into a 10 mL volumetric flask, and then diluted to 10 mL with dichloromethane to obtain a concentration of 1 × 10⁻⁶ mol / L. -4A 100 ml / L test solution was prepared. The test solution was taken using a 2 mm diameter capillary tube, and the letters "HBT" were written on a practice banknote without a fluorescent background. The banknote was then photographed under natural light, irradiated with 365 nm UV light, irradiated with 365 nm UV light for 30 min, and after being placed in a natural environment for 7 days followed by irradiation with 365 nm UV light. The results are as follows: Figure 15 As shown, the mark is not visible in sunlight. Figure 15 (b) is visible in 365nm ultraviolet light. Figure 15 (d) indicates that the compound can be used as an invisible fluorescent ink; furthermore, whether it is left to stand naturally for 7 days before irradiation or continuously irradiated for 30 minutes, the written fluorescent markings can still be observed. Figure 15 In (e)-(f)), after being placed in a natural environment for 30 days and then irradiated with 365nm ultraviolet light, the observed fluorescence intensity was no different from that on day 7. Furthermore, after 72 days of natural placement and irradiation with a 365nm ultraviolet lamp, significant fluorescence was still observed. Figure 16 This indicates that DTPA-HBT has good stability. In conclusion, DTPA-HBT can be used as an invisible ink for fluorescent anti-counterfeiting applications.

Claims

1. A compound exhibiting both dehydroabsic acid aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics, characterized in that, It exhibits both aggregation-induced emission enhancement and intramolecular proton transfer in the excited state, and its structural formula is as follows: 。 2. A method for preparing the compound with dual characteristics of dehydroabsic acid group aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) as described in claim 1, characterized in that, The synthesis route is as follows: 。 3. The preparation method according to claim 2, characterized in that, Under nitrogen protection, DTPA-Bpin and 2-(benzo[d]thiazolyl)-4-bromophenol were used as raw materials, and potassium carbonate and tetra(triphenylphosphine)palladium were added. The Suzuki coupling reaction was carried out in a mixed solution of tetrahydrofuran and water. After the reaction was completed, the mixture was cooled and purified to obtain the AIE / ESIPT dual-characteristic compound DTPA-HBT. The structural formula of DTPA-Bpin is as follows: .

4. The preparation method according to claim 3, characterized in that, The molar ratio of DTPA-Bpin to 2-(benzo[d]thiazolyl)-4-bromophenol, potassium carbonate, and tetra(triphenylphosphine)palladium is 1:(1~1.1):(1~1.2):(0.02~0.03).

5. The preparation method according to claim 3 or 4, characterized in that, The reaction temperature is 35~45 ℃, and the reaction time is 36~48 h.

6. The preparation method according to claim 3 or 4, characterized in that, The purification process involved extracting the cooled material with dichloromethane and water, collecting the organic phase, and then sequentially drying it with anhydrous magnesium sulfate, separating and purifying it by column chromatography, rotary evaporation, and drying to obtain the AIE / ESIPT dual-characteristic compound DTPA-HBT. The eluent used for column chromatography separation and purification was a mixture of petroleum ether and ethyl acetate in a volume ratio of (24-26):

1.

7. The preparation method according to claim 3 or 4, characterized in that, The preparation method of DTPA-Bpin is as follows: DTPA-Br and bis(pinacolyl)diboron are dissolved in dimethyl sulfoxide, and nitrogen gas is introduced for protection. Potassium acetate and [1,1′-bis(diphenylphosphine)ferrocene]palladium(II)dichloromethane complex are added. The reaction is carried out at 70~80℃ for 20~24h. After cooling, the mixture is extracted with dichloromethane and water. The organic phase is collected, dried with anhydrous magnesium sulfate, purified by column chromatography, the solvent is removed by rotary evaporation, and the mixture is dried under vacuum to obtain white solid DTPA-Bpin. The structural formula of DTPA-Br is as follows: .

8. The preparation method according to claim 7, characterized in that, The molar ratio of DTPA-Br, bis(pinacolyl)diboron, potassium acetate, and [1,1′-bis(diphenylphosphine)ferrocene]palladium(II)dichloromethane complex was 1:(1.8~2):(3.5~4):(0.04~0.06).

9. The preparation method according to claim 3 or 4, characterized in that, The preparation method of 2-(benzo[d]thiazol-2-yl)-4-bromophenol is as follows: 5-bromosalicylic aldehyde and o-aminothiophenol are dissolved in water, aminosulfonic acid is added, and the mixture is stirred at room temperature for 0.5-1 h. The mixture is filtered and washed with water to obtain a crude product, which is then recrystallized from a water-ethanol mixed solvent to obtain a yellow solid 2-(benzo[d]thiazol-2-yl)-4-bromophenol. The molar ratio of 5-bromosalicylic aldehyde, o-aminothiophenol and aminosulfonic acid is 1: (1-1.1): (0.03-0.04).

10. The use of the compound with dual characteristics of dehydroabsic acid group aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) as described in claim 1, characterized in that, Use for fluorescent imaging for purposes other than disease diagnosis and treatment; or, use for the preparation of fluorescent dyes; or, use for fluorescent anti-counterfeiting purposes.

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