Preparation methods and applications of dehydroabscisic acid-based DA-type polar responsive fluorescent compounds

Abstract

This invention relates to the field of dehydroabietic acid compounds, specifically disclosing the preparation method and application of dehydroabietic acid-based D-A type polar responsive fluorescent compounds. These compounds include dehydroabietic acid thiadiazole-carbazole, dehydroabietic acid thiadiazole-triphenylamine, dehydroabietic acid thiadiazole-dimethylaniline, and dehydroabietic acid thiadiazole-phenoxazine. This invention introduces groups with different electron-donating abilities onto the natural acceptor dehydroabietic acid thiadiazole to obtain dehydroabietic acid-based D-A type fluorescent compounds, thus developing dehydroabietic acid-based D-A type fluorescent compounds for the first time. These dehydroabietic acid-based D-A type fluorescent compounds exhibit good fluorescence performance accompanied by a redshift in fluorescence wavelength due to increased electron-donating ability, while also possessing good polar response performance. Among them, the good biocompatibility and steroid-like skeleton structure of dehydroabietic acid thiadiazole-dimethylaniline enable specific targeting of lipid droplets, making it a promising fluorescent probe for application in the field of bioimaging and demonstrating excellent practicality.

Description

Technical Field

[0001] This invention relates to the field of dehydroabsic acid compounds, specifically to a method for preparing dehydroabsic acid-based DA-type polar responsive fluorescent compounds and their bioimaging applications. Background Technology

[0002] Natural products have attracted attention due to their unique pharmacological properties, renewability, biodegradability, and excellent biocompatibility. Among them, the simple structure of natural small molecule dehydroabietic acid can be used to construct steroid analogs with tetracyclic structures, thereby building bio-based aggregation-induced emission (BioAIE) materials. Rosin, derived from natural pine resin, is a renewable resource containing benzene rings, alicyclic rings, and oxygen atoms. It has good biocompatibility, and its derivatives have broad prospects for biological applications. [Xu-Min Cai, Yuting Lin, Ying Li, et al. Nature Communications, 2021, 12(1), 1773.]. Benefiting from the diversity and ease of modification of electron donors, electron donor-based regulation has become the dominant design strategy for constructing DA-type fluorescent molecules. However, the types of electron acceptors are relatively limited, mainly concentrated in naphthalimide, imidazole, benzothiadiazole, etc. Common acceptor structures are derived from fossil fuels, and research on natural acceptors is scarce. [Aiyan Ji, Hongyue Lou, Chunrong Qu, et al. Nature Communications, 2022, 13(1), 3815.]. Therefore, developing novel natural A-type BioAIE materials with polar response is of great significance.

[0003] Fluorescent probes have been widely used in biomedical fields such as physiological imaging, environmental monitoring, and clinical diagnosis. It is well known that local environmental parameters in biological systems (e.g., polarity, viscosity, pH) play a crucial role in regulating transport, diffusion, and intermolecular interactions. Abnormal changes in these parameters are closely related to certain physiological dysfunctions or diseases [Xiaojun Qin, Xingye Yang, Lupei Du, et al. RSC Medical Chemistry, 2021, 12, 1826-1838.]. Currently, small molecule fluorescent probes have advantages such as real-time detection, high sensitivity, and high specificity, and have been widely developed for monitoring dynamic cell polarity. However, fluorescent probes used for lipid droplet imaging currently face significant limitations, such as small Stokes shift and low quantum yield [Rikitha S Fernandes, Ambati Himaja, Balaram Ghosh, et al. ACS Applied Bio Materials, 2024, 7, 12, 8248-8260]. Therefore, developing high-performance probes for detecting lipid droplet polarity is highly desirable. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a dehydroabsic acid-based DA-type polar responsive fluorescent compound, its preparation method, and its bioimaging applications.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: a dehydroabsic acid-based DA-type polar responsive fluorescent compound, the structural formula of which is as follows:

[0006]

[0007] R is selected from N-phenylcarbazole or triphenylamine, N,N-dimethylaniline or phenoxazine.

[0008] The dehydroabsic acid-based DA-type polar responsive fluorescent compound of the present invention preferably has R as N,N-dimethylaniline; the preferred dehydroabsic acid thiadiazole-dimethylaniline has excellent polar sensitivity properties and can be used for specific targeting of lipid droplets.

[0009] This invention provides a method for preparing a dehydroabsic acid-based DA-type polar responsive fluorescent compound, comprising the following steps:

[0010] Step 1) Dehydroabscisic acid thiadiazole was coupled with 4-(9H-carbazole-9-yl)phenylboronic acid to obtain compound I: dehydroabscisic acid thiadiazole-carbazole;

[0011]

[0012] Step 2) Dehydroabscisic acid thiadiazole is coupled with 4-(diphenylamino)phenylboronic acid to obtain compound II: dehydroabscisic acid thiadiazole-triphenylamine;

[0013]

[0014] Step 3) The dehydroabietic thiadiazole was coupled with 4-(N,N-dimethylamino)phenylboronic acid pinacol ester to obtain compound III: dehydroabietic thiadiazole-dimethylaniline;

[0015]

[0016] Step 4) The dehydroabietic thiadiazole was coupled with phenoxazine to obtain compound IV: dehydroabietic thiadiazole-phenoxazine;

[0017]

[0018] In the preparation method of the present invention, the Suzuki coupling reaction in steps 1), 2), and 3) is carried out in an organic solvent under anaerobic and alkaline conditions, with tetrakis(triphenylphosphine)palladium as the catalyst, and is obtained by heating.

[0019] In the preparation method of this invention, steps 1), 2), and 3) involve a Suzuki coupling reaction, with toluene as the organic solvent, potassium carbonate aqueous solution as the alkaline environment, a heating temperature of 115–120°C, and a reaction time of 6–8 h.

[0020] In steps 1), 2), and 3) of the preparation method of this invention, the Suzuki coupling reaction involves a molar ratio of dehydroabietic thiadiazole to 4-(9H-carbazole-9-yl)phenylboronic acid, 4-(diphenylamino)phenylboronic acid, or 4-(N,N-dimethylamino)phenylboronic acid pinacol ester at 1.2:1 to 1; and a molar ratio of 4-(9H-carbazole-9-yl)phenylboronic acid, 4-(diphenylamino)phenylboronic acid, or 4-(N,N-dimethylamino)phenylboronic acid pinacol ester to the catalyst at 25:1.

[0021] In step 4) of the preparation method of the present invention, the Buchwald-Hartwig coupling reaction is carried out in an organic solvent under anaerobic and alkaline conditions, and the catalysts are tris(dibenzylacetone)dipalladium and tritert-butylphosphite tetrafluoroborate, which are heated to obtain the product.

[0022] In step 4) of the preparation method of this invention, the Buchwald-Hartwig coupling reaction is carried out using toluene as the organic solvent, sodium tert-butoxide as the alkaline environment, and the heating temperature is 115-120°C.

[0023] In step 4) of the preparation method of this invention, the molar ratio of dehydroabscitic acid thiadiazole to phenoxazine is 1.2:1-1; and the molar ratio of phenoxazine to catalyst is 25:1.

[0024] This invention provides the application of dehydroabscisic acid-based DA-type polar responsive fluorescent compounds in bioimaging, where R in the compound is N,N-dimethylaniline. Specifically, in bioimaging, compound III can specifically target lipid droplets, with a Pearson correlation coefficient of 0.91.

[0025] The advantages of this invention are as follows: The compounds in this invention are the first to develop polar responsive fluorescent compounds based on dehydroabsic acid DA type, and the introduction of groups with different electron-donating abilities creates conditions for studying the structure-activity relationship of dehydroabsic acid DA type compounds; this series of dehydroabsic acid DA type compounds based on novel natural electron acceptors all have good fluorescence performance and are accompanied by a red shift in fluorescence wavelength with increased electron-donating ability, while also having good polar response performance; and specific targeting of lipid droplets is achieved based on the good biocompatibility and steroid-like skeleton structure of dehydroabsic acid thiadiazole-dimethylaniline. Attached Figure Description

[0026] Figure 1 The 1H NMR spectrum of compound (I) is shown.

[0027] Figure 2 The 1H NMR spectrum of compound (II) is shown.

[0028] Figure 3 The 1H NMR spectrum of compound (III) is shown.

[0029] Figure 4 The 1H NMR spectrum of compound (IV) is shown.

[0030] Figure 5 (a) shows the UV-Vis absorption spectrum of compound (II); (b) shows the fluorescence spectra at different water contents.

[0031] Figure 6 (a) shows the UV-Vis absorption spectrum of compound (II); (b) shows the fluorescence spectra at different water contents.

[0032] Figure 7 (a) shows the UV-Vis absorption spectrum of compound (III); (b) shows the fluorescence spectra at different water contents.

[0033] Figure 8 (a) shows the UV-Vis absorption spectrum of compound (IV); (b) shows the fluorescence spectra at different water contents.

[0034] Figure 9 Normalized solid-state fluorescence spectra of compounds (I), (II), (III), and (IV);

[0035] Figure 10 (a) shows the fluorescence spectra of compound (III) in solvents of different polarities; (b) shows the fluorescence lifetime spectra in solvents of different polarities.

[0036] Figure 11 Confocal imaging of lipid droplets of compound (III);

[0037] Figure 12 A comparison of the polar response performance of compound (III) and DAMB-SAN;

[0038] Figure 13 A comparison of quantum yields for compound (III) and DAMB-SAN;

[0039] Figure 14 A comparison of the polar response performance of compound (III) and intermediate DABT-Br;

[0040] Figure 15 A comparison of the quantum yields of compound (III) and intermediate DABT-Br. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0042] Example 1: Synthesis of dehydroabhidiazole-carbazole (I)

[0043] Under nitrogen atmosphere, 0.5 mmol of dehydroabietic thiadiazole intermediate, 0.5 mmol of 4-(9H-carbazole-9-yl)phenylboronic acid, and 0.02 mmol of tetra(triphenylphosphine)palladium catalyst were added sequentially. Then, 2 mL of dry toluene and 1 mL of 2 mol / L potassium carbonate solution were slowly added, and the reaction was heated and stirred at 115 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature, extracted three times with dichloromethane, and washed once with saturated sodium chloride aqueous solution. The mixture was dried, filtered, and the filtrate was distilled under reduced pressure to remove toluene, yielding an oily crude product. Silica gel column chromatography (eluent: petroleum ether / ethyl acetate, v / v: 15:1) gave compound (I) as a white solid in 65% yield. Melting point: 303.3–304.5 °C.

[0044] Compound I 1 The H-NMR spectrum (CDCl3, δ / ppm, 600MHz) is shown below. Figure 1As shown: 8.18-8.14 (m, 4H), 7.81 (s, 1H), 7.74 (d, J = 6.9 Hz, 2H), 7.61-7.55 (m, 2H), 7.44 (m, 2H), 7.31 (m, 2H), 3.74-3.69 (m, 3H), 3.48-3.45 (m, 1H), 3.30-3.2 5 (m, 1H), 2.53 (d, J = 11.8Hz, 1H), 2.44 (d, J = 12.1Hz, 1H), 2.00 (m, 1H), 1.92- 1.84 (m, 3H), 1.74 (d, J=10.9Hz, 1H), 1.67 (m, 2H), 1.41 (s, 3H), 1.37 (s, 3H).

[0045] The above NMR characterization results indicate that dehydroabicinate thiadiazole-carbazole was obtained, and its structure is as follows:

[0046]

[0047] Example 2: Synthesis of dehydroabietic thiadiazole-triphenylamine(II)

[0048] Under nitrogen atmosphere, 0.5 mmol of compound (V), 0.5 mmol of 4-(diphenylamino)phenylboronic acid, and 0.02 mmol of tetra(triphenylphosphine)palladium catalyst were added sequentially. Then, 2 mL of dry toluene and 1 mL of 2 mol / L potassium carbonate solution were slowly added, and the reaction was heated and stirred at 115 °C for 6 h. After the reaction was complete, the mixture was cooled to room temperature, extracted three times with dichloromethane, and washed once with saturated sodium chloride aqueous solution. The mixture was dried, filtered, and the filtrate was distilled under reduced pressure to remove toluene, yielding an oily crude product. Silica gel column chromatography (eluent: petroleum ether / ethyl acetate, v / v: 15:1) gave compound (II) as a yellow solid in 70% yield. Melting point: 208.0–208.6 °C.

[0049] Compound II 1 The H-NMR spectrum (CDCl3, δ / ppm, 600MHz) is shown below. Figure 1As shown: 7.77 (d, J = 6.8 Hz, 2H), 7.63 (s, 1H), 7.26 (s, 4H), 7.17 (s, 6H), 7.03 (s, 2H), 3.69 (s, 3H), 3.39 (d, J = 16.9 Hz, 1H), 3.22-3.18 (m, J = 24.2 Hz, 1H), 2.44 ( d, J=12.0Hz, 1H), 2.37 (d, J=12.0Hz, 1H), 1.93 (s, 1H), 1.86-1.76 (m, J=62.8 Hz, 3H), 1.69 (d, J=8.6Hz, 1H), 1.61-1.57 (m, 2H), 1.33 (s, 3H), 1.32 (s, 3H).

[0050] The above NMR characterization results indicate that dehydroabicinylthiadiazole-triphenylamine was obtained, and its structure is as follows:

[0051]

[0052] Example 3: Synthesis of dehydroabietic thiadiazole-dimethylaniline (III)

[0053] Under nitrogen atmosphere, 0.5 mmol of compound (V), 0.5 mmol of 4-(N,N-dimethylamino)phenylboronic acid pinacol ester, and 0.02 mmol of tetra(triphenylphosphine)palladium catalyst were added sequentially. Then, 2 mL of dry toluene and 1 mL of 2 mol / L potassium carbonate solution were slowly added, and the mixture was heated and stirred at 115 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature, extracted three times with dichloromethane, and washed once with saturated sodium chloride aqueous solution. The mixture was dried, filtered, and the filtrate was distilled under reduced pressure to remove toluene, yielding an oily crude product. Silica gel column chromatography (eluent: petroleum ether / ethyl acetate, v / v: 15:1) gave compound (III) as an orange solid in 50% yield. Melting point: 149.3–150.2 °C.

[0054] Compound III 1 The H-NMR spectrum (CDCl3, δ / ppm, 600MHz) is shown below. Figure 3Shown: 7.82 (d, J=8.6Hz, 2H), 7.61 (s, 1H), 6.88 (d, J=8.6Hz, 2H), 3.71 (s, 3H), 3 .41-3.37(m, 1H), 3.23-3.17(m, 1H), 3.03(s, 6H), 2.45(d, J=12.9Hz, 1H), 2. 39(d, J=12.2Hz, 1H), 1.98-1.91(m, 1H), 1.88-1.77(m, 3H), 1.69-1.63(d, J= 10.7Hz, 1H), 1.62 (d, J=11.9Hz, 1H), 1.60 (s, 1H), 1.35 (s, 3H), 1.34 (s, 3H).

[0055] The above NMR characterization results indicate that dehydroabicinylthiadiazole-dimethylaniline was obtained, and its structure is as follows:

[0056]

[0057] Example 4: Synthesis of dehydroabscisic acid thiadiazole-phenoxazine (IV)

[0058] Under nitrogen atmosphere, 0.5 mmol of compound (V), 0.5 mmol of phenoxazine, 0.02 mmol of tris(dibenzylacetone)dipalladium(O) catalyst, 0.5 mmol of sodium tert-butoxide, and 0.25 mmol of tritert-butylphosphine tetrafluoroborate were added sequentially. Then, 2 mL of dry toluene solution was slowly added, and the mixture was heated and stirred at 115 °C for 6 h. After the reaction was completed, the mixture was cooled to room temperature, extracted three times with dichloromethane, and washed once with saturated sodium chloride aqueous solution. The mixture was dried, filtered, and the filtrate was distilled under reduced pressure to remove toluene, yielding an oily crude product. Silica gel column chromatography (eluent: petroleum ether / ethyl acetate, v / v: 15:1) gave compound (IV) as a red solid in 55% yield. Melting point: 213.8–214.4 °C.

[0059] Compound IV 1 The H-NMR spectrum (CDCl3, δ / ppm, 600MHz) is shown below. Figure 3 Shown: 7.69 (s, 1H), 6.75 (d, J = 7.9Hz, 2H), 6.68-6.65 (m, 2H), 6.55-6.52 (m, 2H), 5.79 (d, J = 8.0Hz, 2H), 3.73 (s, 3H), 3.49-3.45 ( m, 1H), 3.31-3.24 (m, 1H), 2.42 (d, J=12.5Hz, 1H), 2.32-2.26 (m, 1H), 2.02-1.94 (m, 1H), 1.84-1.66 (m, 5H), 1.43-1.34 (m, 7H).

[0060] The above NMR characterization results indicate that dehydroabicinate thiadiazole-phenoxazine was obtained, and its structure is as follows:

[0061]

[0062] Example 5: Determination of the aggregation-induced emission (AIE) optical properties of dehydroabsic acid-based DA-type fluorescent compound I.

[0063] In THF / H2O media with different ratios, the concentration of dehydroabsic acid-based DA-type fluorescent compound I was fixed at 10 μmol / L. Fluorescence spectroscopy analysis was performed using a UV-Vis spectrophotometer and a fluorescence spectrometer (excitation wavelength 373 nm). The fluorescence spectrum of compound 1 is shown below. Figure 5 .

[0064] from Figure 5 As can be seen in (a), compound I has a distinct CT peak, with its maximum absorption wavelength at 373 nm.

[0065] from Figure 5 As can be seen in (b), compound I exhibits distorted intramolecular charge transfer properties. When the medium has a low water content (0%-60%), the emission wavelength gradually red-shifts and the fluorescence intensity decreases. When the medium has a high water content (70%-99%), the emission wavelength blue-shifts and the fluorescence intensity increases, indicating that compound I has TICT-AIE characteristics.

[0066] Example 6: Determination of the aggregation-induced emission (AIE) optical properties of dehydroabsic acid-based DA-type fluorescent compound II.

[0067] In THF / H2O media with different ratios, the concentration of dehydroabsic acid-based DA-type fluorescent compound I was fixed at 10 μmol / L. Fluorescence spectroscopy analysis was performed using a UV-Vis spectrophotometer and a fluorescence spectrometer (excitation wavelength 411 nm). The fluorescence spectrum of compound 1 is shown below. Figure 6 .

[0068] from Figure 6 As can be seen in (a), compound II has a distinct CT peak, with its maximum absorption wavelength at 411 nm.

[0069] from Figure 6 As can be seen in (b), compound II exhibits distorted intramolecular charge transfer properties. When the medium has a low water content (0%-60%), the emission wavelength gradually red-shifts and the fluorescence intensity decreases. When the medium has a high water content (70%-99%), the emission wavelength blue-shifts and the fluorescence intensity increases, indicating that compound II has TICT-AIE characteristics.

[0070] Example 7: Determination of the aggregation-induced emission (AIE) optical properties of dehydroabsic acid-based DA-type fluorescent compound III.

[0071] In THF / H2O media with different ratios, the concentration of dehydroabsic acid-based DA-type fluorescent compound III was fixed at 10 μmol / L. Fluorescence spectroscopy analysis was performed using a UV-Vis spectrophotometer and a fluorescence spectrometer (excitation wavelength 424 nm). The fluorescence spectrum of compound III is shown below. Figure 5 .

[0072] from Figure 7 As can be seen in (a), compound III has a distinct CT peak, with its maximum absorption wavelength at 424 nm.

[0073] from Figure 7 As can be seen in (b), compound III exhibits distorted intramolecular charge transfer properties. When the medium has a low water content (0%-70%), the emission wavelength gradually red-shifts and the fluorescence intensity decreases. When the medium has a high water content (80%-99%), the emission wavelength blue-shifts and the fluorescence intensity increases. This indicates that compound II has TICT-AIE characteristics.

[0074] Example 8: Determination of the aggregation-induced emission (AIE) optical properties of dehydroabsic acid-based DA-type fluorescent compound IV.

[0075] The concentration of dehydroabscisic acid-based DA-type fluorescent compound IV was fixed at 10 μmol / L in THF / H2O media with different ratios. Fluorescence spectroscopy analysis was performed using a UV-Vis spectrophotometer and a fluorescence spectrometer (excitation wavelength 314 nm). The fluorescence spectrum of compound IV is shown below. Figure 5 .

[0076] from Figure 8 As can be seen in (a), the maximum absorption wavelength of compound IV is at 314 nm.

[0077] from Figure 8 As can be seen in (b), the fluorescence intensity increases with the increase of water content in the medium, indicating that compound IV has AIE properties.

[0078] Example 9: Determination of the optical properties of solid-state DA-type fluorescent compounds with dehydroabsic acid group.

[0079] Fluorescence spectroscopy analysis was performed on it using a fluorescence spectrometer. The fluorescence spectrum of the obtained dehydroabsic acid DA-type fluorescent compound is shown in the figure. Figure 9 .

[0080] from Figure 9It can be seen that the emission wavelength of compounds I, II, III and IV exhibits a redshift trend as their electron-donating ability increases.

[0081] Example 10: Determination of the polar response performance of dehydroabsic acid-based DA-type fluorescent compound III.

[0082] Compound III was subjected to fluorescence spectroscopy analysis using a fluorescence spectrometer in different polar solvents (cyclohexane, ethyl acetate, acetone, and dimethyl sulfoxide) at a fixed concentration of 10 μmol / L. The fluorescence spectrum of compound III is shown in [Figure number missing]. Figure 10 .

[0083] from Figure 10 As can be seen in (a), the emission wavelength of compound III red-shifts from 516 nm (cyclohexane) to 668 nm (dimethyl sulfoxide) as the solvent polarity increases, a red shift of 152 nm, indicating a sensitive polar response.

[0084] from Figure 10 As can be seen in (b), the fluorescence lifetime of compound III decreases from 10.8 ns (cyclohexane) to 1.9 ns (dimethyl sulfoxide) with increasing solvent polarity, showing a certain regular trend. It can be used as a fluorescent probe for monitoring polarity changes in the biological microenvironment.

[0085] Example 11: Application of lipid droplet imaging of dehydroabsic acid group DA type fluorescent compound III.

[0086] HeLa cells were cultured in DMEM or RPMI 1640 medium supplemented with 10% fetal bovine serum and 100 μg / mL. -1 Streptomycin and 100 U / mL -1 Penicillin. Cells were cultured in a humidified incubator at 37°C under an atmosphere of 5% CO2 and 95% air (normal oxygen, 5% CO2).

[0087] HeLa cells were seeded in Corning culture dishes for 24 h and then incubated with compound (III) (20 μM). Then, they were incubated with Lipidtox Deep Red (LIPDR, 100 nM). Deep Red FM (LTDR, 200nM) or Cells were stained with Green FM (MTG, 200 nM) for 15 minutes. Cells were washed twice with PBS and immediately imaged using a confocal microscope to obtain fluorescence images. Compound (III): λ ex =405nm, λ em =590±20nm; LIPDR:λ ex =640nm, λ em=680±20nm; LTDR:λ ex =633nm; λ em =720±20nm; MTG:λ ex =488nm, λ em =510±20nm. From Figure 10 It can be seen that compound (III) has a high degree of overlap with LIPDR and can specifically target lipid droplets, with a Pearson correlation coefficient of 0.91. Compound III has a relatively weak ability to target lysosomes and mitochondria (LTDR: 0.74, MTG: 0.58).

[0088] Comparative Example 1:

[0089] Compared with the DAMB-SAN molecule (as shown in Formula VI) in the literature [Xu-Min Cai, Yuting Lin, Ying Li, et al. Nature Communications, 2021, 12(1), 1773.], the difference is that compound (III) has excellent polar response properties, while DAMB-SAN has no polar response properties. Figure 12 As shown.

[0090] Comparative Example 2:

[0091] Compared with the DAMB-SAN molecule in the literature [Xu-Min Cai, Yuting Lin, Ying Li, et al. Nature Communications, 2021, 12(1), 1773.], the difference is that compound (III) has a stronger quantum yield of 54.5%, while DAMB-SAN has a quantum yield of 4.9%. Figure 13 As shown.

[0092] Comparative Example 3:

[0093] Compared to the intermediate DABT-Br, the difference lies in that compound (III) exhibits excellent polar response, while DABT-Br shows weaker polar response. For example... Figure 14 As shown.

[0094] Comparative Example 4:

[0095] Compared to the intermediate DABT-Br, the difference lies in that compound (III) has a significantly higher quantum yield of 54.5%, while DABT-Br has a quantum yield of 0%. Figure 15 As shown.

[0096]

[0097] It should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any combination or equivalent transformation made based on the above embodiments shall fall within the scope of protection of the present invention.

Claims

1. A dehydroabsic acid-based DA-type polar responsive fluorescent compound, characterized in that, Its structural formula is as follows: Compound I: I Compound II: II Compound III: III Compound IV: IV。 2. The use of a fluorescent compound of formula I-III as described in claim 1 in the preparation of lipid droplet bioimaging reagents.

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