Difluorobenzothiadiazole full-color fluorescent molecules, preparation and application thereof

Abstract

This invention discloses a difluorobenzothiadiazole-based panchromatic fluorescent molecule and its preparation and application. The structural formula of this difluorobenzothiadiazole-based fluorescent molecule is shown in formula (1): In formula (1), R is independently selected from silyl, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, and substituted or unsubstituted heteroaryl. The difluorobenzothiadiazole-based fluorescent molecule provided by this invention has a novel structure and is a compound with higher fluorescence intensity, quantum yield, and longer lifetime. It can achieve fluorescence emission across the entire visible range from blue to red in liquid, solid, and thin film states.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent materials, specifically relating to a difluorobenzothiadiazole-based panchromatic fluorescent molecule and its preparation and application. Background Technology

[0002] Phenochromatic fluorescent molecules are compounds that emit fluorescence across the entire visible spectrum. Their diverse emission properties make them promising for applications in chemical sensing, cell imaging, and organic optoelectronic materials. Therefore, developing small phenochromatic fluorescent molecules with simple structures, broad emission ranges, and diverse fluorescence properties is of great significance.

[0003] For a long time, the panchromatic fluorescent materials reported in literature and patents have mainly included the following types:

[0004] (1) Quantum dots: Quantum dots are nanocrystals (inorganic nanocrystals) with a size range of 2-50 nm. Their emission range can be controlled / adjusted by controlling the particle size, surface chemistry, distribution, and constituent materials of quantum dots. For example, small quantum dots emit blue light, while larger quantum dots emit red light. Nanomaterials with a size of 1-100 nm also exhibit similar variations.

[0005] (2) Carbon dots: Carbon dots are zero-dimensional carbon nanomaterials with a diameter of 2-10 nm, which have tunable photoluminescence properties. Among them, carbon dots prepared by different carbon sources or different synthesis methods have different emission behaviors. Usually, their emission is controlled by changing the structure, physical state and morphology of carbon dots.

[0006] (3) Plexichromic small organic molecules: Plexichromic small organic molecules refer to a class of donor-acceptor (DA) type organic compounds with chromophores. Usually, their emission is regulated by controlling the fluorescence of substituents with different electron-donating or electron-withdrawing properties in the acceptor or donor core.

[0007] Traditional cadmium / lead quantum dots, rare-earth nanomaterials, and emerging carbon dots possess advantages such as good photostability and high quantum yield. However, they also have some fatal drawbacks. For example, poor reproducibility and unclear luminescence mechanisms and structure-activity relationships greatly limit their application as panchromatic luminescent materials in various fields.

[0008] Phenochromatic small organic molecules are becoming a hot topic for constructing phenochromatic fluorescent materials due to their significant advantages, such as well-defined luminescence mechanisms, clear structure-activity relationships, and diverse luminescence properties. However, current phenochromatic fluorescent molecules still suffer from drawbacks such as a limited number of usable core frameworks and narrow luminescence ranges, and ideal phenochromatic fluorescent molecules remain scarce. Therefore, developing novel phenochromatic fluorescent molecules, studying their structure-activity relationships, and expanding their applications in fluorescence detection remain of great importance.

[0009] Phenomenon-fluorescent small molecules have advantages such as small size and flexible structural modification, therefore, fluorescent materials emitting light across the entire visible light range are highly dependent on organic small molecule compounds. Currently, there are two main strategies for constructing phenomenon-fluorescent small molecules: one is to select an acceptor core and simultaneously introduce different electron donors (D) at both ends of the acceptor (A) to construct DAD-type molecules; the other is to select a donor core, introduce different electron donors (D) at one end of the donor and different electron acceptors (A) at the other end to construct DDA-type molecules.

[0010] Both methods can easily construct molecules with intramolecular charge transfer (ICT) effects of varying intensities. Enhanced ICT effects lead to a redshift in the absorption and emission spectra. For example, Sun's group disclosed in doi.org / 10.1002 / chem.202203797 that they designed eight DDA-type full-color aggregation-induced emission molecules using carbazole as the core. Yasuda's group disclosed in doi.org / 10.1002 / adfm.201505106 that they synthesized five DAD-type full-color thermally delayed fluorescence materials using phthalonitrile or dicyanpyrazine as the acceptor core and coupling them with different donors.

[0011] In summary, panchromatic fluorescent molecules are frequently used in fluorescence sensing, cell imaging, and other fields due to their wide and diverse emission properties. Therefore, there is a strong demand for novel panchromatic fluorescent molecules with superior performance in various fluorescent materials fields. However, currently reported panchromatic fluorescent molecules still suffer from drawbacks such as narrow emission ranges and limited fluorescence properties. Summary of the Invention

[0012] To overcome the problems existing in the prior art, one objective of this invention is to provide a panchromatic fluorescent molecule synthesized from a difluorobenzothiadiazole fluorophore. A second objective is to provide a method for preparing this panchromatic fluorescent molecule synthesized from a difluorobenzothiadiazole fluorophore. A third objective is to provide applications of this panchromatic fluorescent molecule synthesized from a difluorobenzothiadiazole fluorophore.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] The first aspect of this invention provides a difluorobenzothiadiazole fluorescent molecule, the structural formula of which is shown in formula (1):

[0015]

[0016] In formula (1), R is independently selected from silyl, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

[0017] Preferably, in formula (1), R is independently selected from trimethylsilyl, C1-C8 alkyl, thiophenyl, phenyl, halophenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, biphenyl, naphthyl, carbazolylphenyl, 4-(N,N-disubstituted amino)phenyl.

[0018] More preferably, in the formula (1), R is independently selected from trimethylsilyl, butyl, thiophenyl, phenyl, p-methylphenyl, p-methoxyphenyl, p-chlorophenyl, naphthyl, biphenyl, (4-carbazole-9-yl)phenyl, triphenylamino, 4-[N,N-di(4-methoxyphenyl)amino]phenyl, 4-(N,N-dimethylamino)phenyl.

[0019] Preferably, the difluorobenzothiadiazole fluorescent molecule is selected from compounds with the following structures:

[0020]

[0021] The second aspect of this invention provides a method for preparing the difluorobenzothiadiazole fluorescent molecule described in the first aspect of this invention, comprising the following steps: reacting 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole with a terminal alkyne to obtain the difluorobenzothiadiazole fluorescent molecule; wherein the structural formula of the terminal alkyne is shown in formula (2):

[0022]

[0023] In formula (2), R is independently selected from silyl, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl.

[0024] Preferably, in formula (2), R is independently selected from trimethylsilyl, C1-C8 alkyl, thiophenyl, phenyl, halophenyl, C1-C4 alkylphenyl, C1-C4 alkoxyphenyl, biphenyl, naphthyl, carbazolylphenyl, 4-(N,N-disubstituted amino)phenyl.

[0025] More preferably, the terminal alkyne is independently selected from trimethylethynylsilane, 1-hexyne, 2-ethynthiophene, benzoyne, 4-tolylaceyne, 4-ethynylanisole, p-chlorophenylaceyne, 1-ethynylnaphthalene, 4-ethynylbiphenyl, 9-(4-ethynylphenyl)carbazole, 4-ethynyltriphenylamine, N,N-bis(4-methoxyphenyl)-4-ethynylaniline, and 4-N,N-dimethylaminophenylaceyne.

[0026] Preferably, the molar ratio of the 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole to the terminal alkyne is 1:(2-4). More preferably, the molar ratio of the 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole to the terminal alkyne is 1:(2.4-3.6).

[0027] Preferably, the reaction includes the addition of a catalyst; the catalyst comprises a palladium catalyst and a copper(I) salt. More preferably, the catalyst comprises cuprous iodide, dichlorobis(triphenylphosphine)palladium(II), and triphenylphosphine. Even more preferably, the molar ratio of 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole, terminal alkyne, cuprous iodide, dichlorobis(triphenylphosphine)palladium(II), and triphenylphosphine is 1:(2-4):0.1:1:1.

[0028] Preferably, the reaction is carried out at 110–130°C for 20–40 hours.

[0029] Preferably, the reaction is carried out in an inert atmosphere.

[0030] Preferably, the solvent is at least one of triethylamine and tetrahydrofuran. More preferably, the solvent includes triethylamine and tetrahydrofuran.

[0031] The third aspect of the present invention also provides the application of the difluorobenzothiadiazole fluorescent molecules described in the first aspect of the present invention in the preparation of organic light-emitting materials, fluorescent dyes or fluorescent probes.

[0032] The beneficial effects of this invention are:

[0033] The difluorobenzothiadiazole panchromatic fluorescent molecules provided by this invention have a wide emission range, variable fluorescence quantum yield and large Stokes shift, and exhibit good response to organic solvents of different polarities (such as n-hexane, dichloromethane and 1,4-dioxane).

[0034] Specifically, compared with the prior art, the present invention has the following advantages:

[0035] 1) The difluorobenzothiadiazole-based panchromatic fluorescent molecule provided by this invention is a novel panchromatic fluorescent molecule with advantages such as high polarity sensitivity and easy visualization in organic solvent polarity sensing. It not only has a wide emission range, variable fluorescence quantum yield and large Stokes shift, but also has excellent fluorescence intensity, fluorescence quantum yield and fluorescence lifetime compared with benzothiadiazole-based fluorescent molecules.

[0036] 2) This invention modifies the 4 and 7 positions of 5,6-difluorobenzothiadiazole via a Sonogashira coupling reaction, using readily available compounds as starting materials to synthesize a novel full-color fluorescent molecule in one step. The reaction is easily controlled, the product purification is simple, and the yield is consistently above 60%.

[0037] 3) The difluorobenzothiadiazole-based full-color fluorescent molecules provided by this invention have excellent fluorescence performance and can achieve visual response in different solvents, and have good application prospects in the preparation of organic light-emitting materials, fluorescent dyes and fluorescent probes. Attached Figure Description

[0038] Figure 1 The results of FT-IR characterization of 3m difluorobenzothiadiazole fluorescent molecules are shown.

[0039] Figure 2 For difluorobenzothiadiazole fluorescent molecules 3m 1 H NMR characterization results;

[0040] Figure 3 For difluorobenzothiadiazole fluorescent molecules 3m 13 C NMR characterization results;

[0041] Figure 4 For difluorobenzothiadiazole fluorescent molecules 3m 19 F NMR characterization results;

[0042] Figure 5 The HRMS characterization results of 3m for difluorobenzothiadiazole fluorescent molecules;

[0043] Figure 6 The UV absorption spectrum of difluorobenzothiadiazole fluorescent molecule 3a-3m in tetrahydrofuran solvent;

[0044] Figure 7 The fluorescence spectrum of difluorobenzothiadiazole fluorescent molecule 3a-3m in tetrahydrofuran solvent;

[0045] Figure 8 The fluorescence spectrum of difluorobenzothiadiazole fluorescent molecules 3a-3m in solid powder form;

[0046] Figure 9 The fluorescence spectrum of difluorobenzothiadiazole fluorescent molecule 3a-3m in thin film state;

[0047] Figure 10 The fluorescence spectra of difluorobenzothiadiazole fluorescent molecules 3j, 3k, 3l and 3m in different organic solvents are shown. Detailed Implementation

[0048] The present invention will be further described in detail below through specific embodiments.

[0049] Example 1: A method for preparing a difluorobenzothiadiazole fluorescent molecule

[0050] Prepare difluorobenzothiadiazole fluorescent molecules according to the following reaction formula:

[0051]

[0052] In the above reaction formula, the structural formula of the terminal alkyne is shown in formula (2), and the product after the reaction is shown in formula (3a-3m). In formula (2) and formula (3a-3m), R is independently selected from trimethylsilyl, butyl, thiophene, phenyl, p-methylphenyl, p-methoxyphenyl, p-chlorophenyl, naphthyl, biphenyl, (4-carbazole-9-yl)phenyl, triphenylamino, 4-[N,N-di(4-methoxyphenyl)amino]phenyl, 4-(N,N-dimethylamino)phenyl.

[0053] Based on the above chemical reaction formula, the preparation process includes the following steps:

[0054] Weigh 0.2 mmol of 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole and 0.42 mmol of terminal alkyne as starting materials; weigh 0.02 mmol of cuprous iodide, 0.2 mmol of dichlorobis(triphenylphosphine)palladium(II), and 0.2 mmol of triphenylphosphine as catalysts; and measure 3 mL of dry triethylamine and 2 mL of dry tetrahydrofuran as solvents. Place them in a 25 mL Schlenk reaction tube, evacuate, purge with nitrogen, and reflux at 110 °C for 24 h. After the reaction is complete, cool the reaction solution to room temperature and add 2 mL of saturated ammonium chloride solution to quench the reaction. After the reaction was complete, the organic phase was extracted with dichloromethane and ammonium chloride aqueous solution, dried with anhydrous sodium sulfate, and the organic solvent was evaporated under reduced pressure to obtain a crude solid product. Then, using petroleum ether / dichloromethane = 6 / 1 as the eluent, the pure product was obtained by column chromatography, which yielded the difluorobenzothiadiazole fluorescent molecules (3a-3m).

[0055] The specific process for preparing difluorobenzothiadiazole fluorescent molecules is as follows:

[0056] (1) When the terminal alkyne is trimethylethynylsilane, the product obtained is a difluorobenzothiadiazole fluorescent molecule, which is compound 3a, and its structure is shown in formula (3a):

[0057]

[0058] The product was a white solid with a yield of 70.4%. The NMR data of this compound are as follows:

[0059] 1 H NMR (CDCl3, 600MHz): δ = 0.35 (s, 18H) ppm; 13C NMR (CDCl3, 150MHz): δ = 0.19, 92.58, 104.61 (dd, J1 = 13.1Hz, J2 = 5.1Hz), 111.55, 150.66 (dd, J1 = 3.3Hz, J2 = 2.3Hz), 155.61 (dd, J1 = 263.6Hz, J2 = 19.4Hz) ppm; 19 F NMR (CDCl3, 564MHz): δ=-123.69ppm.

[0060] The above test data proves that the product prepared in Example 1(1) is compound 3a.

[0061] (2) When the terminal alkyne is 1-hexyne, the product obtained is a difluorobenzothiadiazole fluorescent molecule, which is compound 3b, and its structure is shown in formula (3b):

[0062]

[0063] The product was a white solid with a yield of 74.0%. The NMR data of this compound are as follows:

[0064] 1 H NMR (CDCl3, 600MHz): δ = 0.98 (t, J = 7.2Hz, 6H), 1.52-1.59 (m, 4H), 1.68-1.73 (m, 4H), 2.64 (t, J = 7.2Hz, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 13.63, 19.88, 22.04, 30.44, 69.55, 103.96 (dd, J1 = 13.4Hz, J2 = 4. 8Hz), 105.61, 150.67 (dd, J1 = 3.6Hz, J2 = 2.4Hz), 154.79 (dd, J1 = 260.4Hz, J2 = 19.4Hz) ppm; 19 F NMR (CDCl3, 564MHz): δ=-125.82ppm.

[0065] The test data above proves that the product prepared in Example 1(2) is compound 3b.

[0066] (3) When the terminal alkyne is 2-acetylenthiophene, the product obtained is a difluorobenzothiadiazole fluorescent molecule, which is compound 3c, and its structure is shown in formula (3c):

[0067]

[0068] The product was an orange solid with a yield of 65.3%. The NMR data for this compound are as follows:

[0069] 1 H NMR (CDCl3, 600MHz): δ = 7.09-7.10 (m, 2H), 7.45 (d, J = 6.0Hz, 2H), 7.51 (d, J = 4.2Hz, 2H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 82.01, 96.80, 103.90 (dd, J1 = 13.2Hz, J2 = 5.9Hz), 121.68, 127.52, 1 29.55, 134.11, 150.07 (dd, J1 = 4.8Hz, J2 = 2.4Hz), 154.04 (dd, J1 = 262.4Hz, J2 = 19.8Hz) ppm; 19 F NMR (CDCl3, 564MHz): δ=-124.24ppm.

[0070] The above test data proves that the product prepared in Example 1(3) is compound 3c.

[0071] (4) When the terminal alkyne is benzyne, the product obtained is a difluorobenzothiadiazole fluorescent molecule, which is compound 3d, and its structure is shown in formula (3d):

[0072]

[0073] The product was a yellow solid with a yield of 76.1%. The NMR data of this compound are as follows:

[0074] 1 H NMR (CDCl3, 600MHz): δ = 7.38-7.43 (m, 6H), 7.66-7.69 (m, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 78.12, 103.46, 104.06 (dd, J1 = 13.1Hz, J2 = 5.1Hz), 121.87, 128.50, 129.66, 132.14, 150.26 (dd, J1 = 3.0Hz, J2 = 2.4Hz), 154.31 (dd, J1 = 262.5Hz, J2 = 18.9Hz) ppm; 19 F NMR (CDCl3, 564MHz): δ=-124.38ppm.

[0075] The above test data proves that the product prepared in Example 1 (4) is compound 3d.

[0076] (5) When the terminal alkyne is 4-tolylacetylene, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3e, whose structure is shown in formula (3e):

[0077]

[0078] The product was a yellow solid with a yield of 78.7%. The NMR data of this compound are as follows:

[0079] 1 H NMR (CDCl3, 600MHz): δ = 2.41 (s, 6H), 7.22 (d, J = 7.8Hz, 4H), 7.59 (d, J = 8.4Hz, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 21.69, 77.71, 103.84, 104.08 (dd, J1 = 13.4Hz, J2 = 5.3Hz), 118.88, 129. 32,132.09,140.12,150.36(dd,J1=3.5Hz,J2=3.2Hz),154.37(dd,J1=262.2Hz,J2=19.4Hz)ppm; 19 F NMR (CDCl3, 564MHz): δ=-124.77ppm.

[0080] The above test data proves that the product prepared in Example 1 (5) is compound 3e.

[0081] (6) When the terminal alkyne is 4-ethynyl anisole, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3f, whose structure is shown in formula (3f):

[0082]

[0083] The product was a yellow solid with a yield of 79.2%. The NMR data of this compound are as follows:

[0084] 1 H NMR (CDCl3, 600MHz): δ = 3.86 (s, 6H), 6.94 (d, J = 8.4Hz, 4H), 7.64 (d, J = 9.0Hz, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 55.41, 103.79, 104.08 (dd, J1 = 12.9Hz, J2 = 4.8Hz), 114.03, 114.22, 1 33.83, 150.39 (dd, J1 = 3.3Hz, J2 = 2.4Hz), 154.14 (dd, J1 = 261.3Hz, J2 = 19.2Hz), 160.75, ppm; 19 F NMR (CDCl3, 564MHz): δ=-125.19ppm.

[0085] The above test data proves that the product prepared in Example 1 (6) is compound 3f.

[0086] (7) When the terminal alkyne is p-chlorophenylacetylene, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3g, whose structure is shown in formula (3g):

[0087]

[0088] The product was a yellow solid with a yield of 73.0%. The NMR data of this compound are as follows:

[0089] 1 H NMR (CDCl3, 600MHz): δ = 7.40 (d, J = 9.0Hz, 4H), 7.63 (d, J = 8.4Hz, 4H) ppm; 13 CNMR (CDCl3, 150MHz): δ = 78.99, 102.33, 104.03 (dd, J1 = 12.5Hz, J2 = 5.6Hz), 120.33), 129.00, 133.38, 135.99, 152.21 (dd, J1 = 3.0Hz, J2 = 2.4Hz), 154.38 (dd, J1 = 262.5Hz, J2 = 19.5Hz), ppm; 19 F NMR (CDCl3, 564MHz): δ=-125.19ppm.

[0090] The above test data proves that the product prepared in Example 1 (7) is compound 3g.

[0091] (8) When the terminal alkyne is 1-ethynylnaphthalene, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3h, whose structure is shown in formula (3h):

[0092]

[0093] The product was a yellow solid with a yield of 72.6%. The NMR data of this compound are as follows:

[0094] 1 H NMR (CDCl3, 600MHz): δ=7.53-7.55(m,2H),7.59-7.62(m,2H),7.70-7.73(m,2H),7.92( d,J=8.4Hz,2H),7.96(d,J=7.8Hz,2H),7.97(d,J=7.8Hz,2H),8.67(d,J=8.4Hz,2H)ppm; 13C NMR (CDCl3, 150MHz): δ = 78.84, 106.61 (dd, J1 = 18.6Hz, J2 = 5.4Hz), 109.48, 125.29, 126.22, 126.82, 127.56, 128. 47,130.41,131.53,133.21,133.32,143.26(dd,J1=4.2Hz,J2=3.5Hz),152.98(dd,J1=260.1Hz,J2=20.6Hz)ppm; 19 F NMR (CDCl3, 564MHz): δ=-124.53ppm.

[0095] The above test data proves that the product prepared in Example 1 (8) is compound 3h.

[0096] (9) When the terminal alkyne is 4-ethynylbiphenyl, the product obtained is a difluorobenzothiadiazole fluorescent molecule, which is compound 3i, and its structure is shown in formula (3i):

[0097]

[0098] The product was a yellow solid with a yield of 75.7%. The NMR data of this compound are as follows:

[0099] 1 H NMR (CDCl3, 600MHz): δ = 7.38-7.41 (m, 2H), 7.47-7.49 (m, 4H), 7.64 (d, J = 7.8Hz, 4H), 7.67 (d, J = 8.4Hz, 4H), 7.78 (d, J = 8.4Hz, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 78.90, 103.57, 103.87 (dd, J1 = 17.1Hz, J2 = 5.6Hz), 120.74, 127.14, 127.22, 127.99, 128.97, 132.65, 140.10, 142.46, 150.38 (dd, J1 = 3.9Hz, J2 = 2.7Hz), 156.24 (dd, J1 = 254.6Hz, J2 = 19.5Hz) ppm; 19 F NMR (CDCl3, 564MHz): δ=-124.40ppm.

[0100] The above test data proves that the product prepared in Example 1 (9) is compound 3i.

[0101] (10) When the terminal alkyne is 9-(4-ethynylphenyl)carbazole, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3j, whose structure is shown in formula (3j):

[0102]

[0103] The product was a yellow solid with a yield of 82.4%. The NMR data of this compound are as follows:

[0104] 1 H NMR (CDCl3, 600MHz): δ = 7.32-7.34 (m, 4H), 7.44 (d, J = 8.4Hz, 4H), 7.46-7.50 ( m,4H),7.68(d,J=8.4Hz,4H),7.96(d,J=8.4Hz,4H),8.16(d,J=7.8Hz,4H)ppm; 13 CNMR (CDCl3, 150MHz): δ = 79.03, 102.87, 103.20 (dd, J1 = 17.8Hz, J2 = 4.2Hz), 109.75, 120.48, 120.63, 123.75, 126 .20,126.92,133.79,139.04,140.41,150.83(dd,J1=4.4Hz,J2=4.2Hz),155.58(dd,J1=273.5Hz,J2=20.7Hz)ppm; 13 C NMR (CDCl3, 150MHz): δ = 79.03, 102.87, 103.20 (dd, J1 = 17.8Hz, J2 = 4.2Hz), 109.75, 120.48, 120.63, 123.75, 126. 20,126.92,133.79,139.04,140.41,150.83(dd,J1=4.4Hz,J2=4.2Hz),155.58(dd,J1=273.5Hz,J2=20.7Hz)ppm; 19 F NMR (CDCl3, 564MHz): δ=-124.03ppm.

[0105] The above test data proves that the product prepared in Example 1 (10) is compound 3j.

[0106] (11) When the terminal alkyne is 4-ethynyltriphenylamine, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3k, whose structure is shown in formula (3k):

[0107]

[0108] The product was a red solid with a yield of 80.6%. The NMR data of this compound are as follows:

[0109] 1H NMR (CDCl3, 600MHz): δ = 7.02 (d, J = 8.4Hz, 4H), 7.08-7.11 (m, 4H), 7.14 (d, J = 7.2Hz, 8H), 7.28-7.31 (m, 8H), 7.50 (d, J = 9.0Hz, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 77.88, 103.92 (dd, J1 = 13.1Hz, J2 = 4.7Hz), 104.25, 124.12, 121.47, 124.06, 125.42, 129.52, 133.19, 146.88, 149.13, 150.39 (dd, J1 = 3.2Hz, J2 = 2.4Hz), 154.01 (dd, J1 = 261.2Hz, J2 = 19.4Hz) ppm; 19 F NMR (CDCl3, 564MHz): δ=-126.01ppm.

[0110] The above test data proves that the product prepared in Example 1 (11) is compound 3k.

[0111] (12) When the terminal alkyne is N,N-bis(4-methoxyphenyl)-4-ethynylaniline, the product obtained is a difluorobenzothiadiazole fluorescent molecule, which is compound 3l, and its structure is shown in formula (3l):

[0112]

[0113] The product was a dark red solid with a yield of 81.9%. The NMR data of this compound are as follows:

[0114] 1 H NMR (CDCl3, 600MHz): δ = 3.81 (s, 12H), 6.86 (d, J = 9.0Hz, 4H), 6.87 (d, J = 9.0Hz, 8H), 7.10 (d, J = 9.0Hz, 8H), 7.45 (d, J = 9.0Hz, 4H) ppm; 13 C NMR (CDCl3, 150MHz): δ = 55.50, 77.60, 103.87 (dd, J1 = 13.1Hz, J2 = 5.4Hz), 104.76, 112.10, 114.91, 118.52, 127.43, 1 33.13, 139.77, 149.92 (C-9, 9′), 150.39 (dd, J1=3.3Hz, J2=3.3Hz), 153.90 (dd, J1=260.4Hz, J2=19.5Hz), 156.65ppm; 19F NMR (CDCl3, 564MHz): δ=-125.89ppm.

[0115] The above test data proves that the product prepared in Example 1 (12) is compound 3l.

[0116] (13) When the terminal alkyne is N,N-bis(4-methoxyphenyl)-4-ethynylaniline, the product obtained is a difluorobenzothiadiazole fluorescent molecule, compound 3m, whose structure is shown in formula (3m):

[0117]

[0118] The product is a red solid with a yield of 85.1% and a melting point of mp > 300.0℃. The FT-IR characterization results of the 3m of the difluorobenzothiadiazole fluorescent molecule prepared in this invention are as follows: Figure 1 As shown, by Figure 1 FT-IR analysis (KBr, ν, cm) -1 ): 3081cm -1 Absorption peaks of the stretching vibration of the aromatic ring unsaturated CH; 2912, 2850 cm⁻¹ -1 alkyl CH stretching vibration absorption peak; 2197 cm⁻¹ -1 Absorption peaks for the stretching vibration of unsaturated C≡C bonds; 1599, 1528, 1434 cm⁻¹ -1 Aromatic ring skeleton stretching vibration absorption peak; 1368 cm⁻¹ -1 Ar-NR2 bond stretching vibration absorption peak; 1185, 1011 cm⁻¹ -1 ,C-F bond stretching vibration absorption peak; 804 cm⁻¹ -1 The benzene ring is para-disubstituted. From the characteristic absorption peaks above, it can be seen that starting material 1 and 2m successfully underwent a Sonogashira metal coupling reaction, and the difluorobenzothiadiazole fluorescent molecule 3m was successfully synthesized.

[0119] The 3m NMR spectra, CMR spectra, fluorine NMR spectra, and mass spectra of the difluorobenzothiadiazole fluorescent molecules prepared in this invention are as follows: Figures 2-5 As shown. The specific NMR results analysis is as follows: 1 H NMR (CDCl3, 600MHz): δ = 3.05 (s, 12H, NCH3), 7.02 (d, J = 9.0Hz, 4H, ArH), 7.50 (d, J = 7.8Hz, 4H, ArH) ppm; 13C NMR (CDCl3, 150MHz): δ = 40.13, 105.45, 103.86 (dd, J1 = 19.5Hz, J2 = 5.6Hz), 108.51, 111.66, 128. 27,133.51,150.50(dd,J1=3.2Hz,J2=2.4Hz),150.87,153.54(dd,J1=259.5Hz,J2=19.4Hz)ppm; 19 F NMR (CDCl3, 564MHz): δ = -126.30ppm; m / z (%): Calcd for C 26 H 21 F2N4S + ([M+H)) + ):459.1450(100),Found:459.1440(100). The above test data proves that the product prepared in Example 1(13) is compound 3m.

[0120] Comparative Example 1: A method for preparing a benzothiadiazole compound

[0121] The reaction formula of the control compound described in this invention is shown below. The specific process is as follows: using 4,7-dibromobenzo[c][1,2,5]thiadiazole 1b and 4-N,N-dimethylaminophenylacetylene 2m as raw materials, a benzothiadiazole compound 3n was synthesized via a Sonogashira coupling reaction, with the reaction method being the same as in Example 1. The yield was 77.8%, while the yield of 3m in Example 1 was 85.1%, indicating that the fluorinated benzothiadiazole skeleton is more favorable for the Sonogashira coupling reaction than the benzothiadiazole skeleton.

[0122]

[0123] Application Example 1

[0124] 1. Ultraviolet spectra of difluorobenzothiadiazole fluorescent molecules 3a-3m in tetrahydrofuran solvent

[0125] Prepare a solution (2 mL, 10 mL) of fluorescent molecule 3a-3m dissolved in tetrahydrofuran (THF). -5 (mol / L); observe the color of the compound 3a-3m solution under fluorescent light; use a UV spectrometer, set appropriate parameters, to test the UV-Vis absorption spectrum of the compound 3a-3m solution. From Figure 6 The visualization shows that compound 3a-3m (concentration of 10) -5 (mol / L) exhibits distinctly different colors in tetrahydrofuran, such as colorless and transparent, yellow-green, yellow, orange, and red. Similarly, through ultraviolet absorption spectra ( Figure 6It can also be found that compound 3a-3m (concentration of 10) -5 The maximum absorption peaks of difluorobenzothiadiazole (mol / L) in tetrahydrofuran are located in different wavelength ranges. This indicates that fluorescent molecules with a wide absorption range can be obtained by changing the substituents at the 4 and 7 positions of difluorobenzothiadiazole.

[0126] 2. Fluorescence spectra of difluorobenzothiadiazole fluorescent molecules 3a-3m and control compound 3n in tetrahydrofuran solvent.

[0127] Prepare a solution (2 mL, 10 mL) of the fluorescent molecule compound 3a-3m dissolved in tetrahydrofuran (THF). -5 (mol / L); observe the fluorescence color of the compound 3a-3m solution under a 365nm UV lamp; use a fluorescence spectrometer, set appropriate parameters, to test the fluorescence emission spectrum of the compound 3a-3m solution. From Figure 7 The visualization shows that compound 3a-3m (concentration of 10) - 5 (mol / L) exhibits distinctly different fluorescent colors in tetrahydrofuran, such as blue, cyan, green, yellow-green, orange, and red. Similarly, the fluorescence spectrum ( Figure 7 It can also be found that compound 3a-3m (concentration of 10) -5 The maximum emission peak of difluorobenzothiadiazole (mol / L) in tetrahydrofuran is located in different emission wavelength ranges. Simultaneously, the fluorescence intensity also varies. This indicates that by changing the substituents at the 4 and 7 positions of difluorobenzothiadiazole, liquid fluorescent molecules with a wide emission range (436-643 nm) can be obtained.

[0128] 3. Fluorescence spectra of difluorobenzothiadiazole fluorescent molecules 3a-3m in solid powder form.

[0129] The fluorescence color of the solid powder of compound 3a-3m was observed under a 365 nm ultraviolet lamp; a fluorescence spectrometer was used, and appropriate parameters were set to test the fluorescence emission spectrum of the solid powder of compound 3a-3m. Figure 8 The visualization reveals that the solid powders of compounds 3a-3m exhibit distinctly different fluorescent colors, such as blue, green, yellow-green, yellow, red, and deep red. Similarly, the fluorescence spectra (…) Figure 8 It was also observed that the maximum emission peaks of the solid powders of compounds 3a-3m were located in different emission wavelength ranges, and the fluorescence intensities also showed significant differences. This indicates that by changing the substituents at the 4 and 7 positions of difluorobenzothiadiazole, solid-state fluorescent molecules with a wide emission range (445-672 nm) can be obtained.

[0130] 4. Fluorescence spectra of difluorobenzothiadiazole fluorescent molecules 3a-3m in thin film state

[0131] Prepare 1 mL probe 3a-3m(10) -3 Weigh 0.1 g of polymethyl methacrylate (PMMA) into a dichloromethane solution (M) and add it to the solution. Let it dissolve naturally at room temperature for 12 hours. Drop the polymer solution onto a clean circular mold and air dry it at room temperature to obtain a thin film fluorescent material of basically uniform size for testing. Observe the fluorescence color of the compound in the 3a-3m thin film state under a 365 nm ultraviolet lamp. Use a fluorescence spectrometer, set appropriate parameters, and test the fluorescence emission spectrum of the compound in the 3a-3m thin film state.

[0132] from Figure 9 The visualization reveals that the compound exhibits distinctly different fluorescence colors in its 3a-3m thin film states, such as blue, blue-green, green, orange, and red. Similarly, the fluorescence spectrum ( Figure 9 As shown in Table 1, the maximum emission peaks of compounds 3a-3m in thin film states are located in different emission wavelength ranges. Simultaneously, the fluorescence intensity also varies significantly. This indicates that by changing the substituents at the 4 and 7 positions of difluorobenzothiadiazole, thin film fluorescent molecules with a wide emission range (445-628 nm) can be obtained.

[0133] 5. Photophysical data of difluorobenzothiadiazole fluorescent molecules 3a-3m and control compound 3m in solution, solid and thin film states.

[0134] The photophysical data of compound 3m in solution, solid, and thin film states were tested using the above method. Combined with the data of 3a-3m, the specific results are shown in Table 1:

[0135] Table 1. Photophysical data of compounds 3a-3n in liquid, solid, and thin film states.

[0136]

[0137] Table 1 shows that the emission peak (λ) of the control compound 3n in solution is... em The emission peak of compound 3m is located at 630 nm, while that of compound 3n is located at 643 nm, indicating that fluorinated benzothiadiazole favors a redshift in emission. Similar changes are observed in both solid and thin film states. Meanwhile, the quantum yield (Φ) of compound 3n in the solid state is compared to that of compound 3n. F a ) and lifetime (τ) b The quantum yield and lifetime of compound 3m were 2.22% and 1.05 ns, respectively, while those of compound 3m were 19.91% and 2.02 ns. This indicates that the introduction of a fluorinated benzothiadiazole core is beneficial for improving fluorescence intensity and fluorescence lifetime.

[0138] 6. Fluorescence properties of difluorobenzothiadiazole fluorescent molecules 3j, 3k, 3l, and 3m in different organic solvents

[0139] Prepare fluorescent molecules 3j, 3k, 3l and 3m (2mL, 10 -5 M) Solutions were dissolved in three different organic solvents: hexane, dichloromethane (DCM), and 1,4-dioxane. The fluorescence colors of the 12 organic solutions were observed under a 365 nm desktop UV lamp. A fluorescence spectrometer was used with appropriate parameters to test the fluorescence emission spectra of the 12 organic solutions.

[0140] from Figure 10 The visualization shows that compound 3j (concentration of 10) -5 The compound 3k (mol / L) exhibited distinctly different fluorescent colors, including green, orange, and yellow-green, in organic solutions of three solvents with different polarities (Table 2); -5 Compound 3l (mol / L) exhibited distinctly different fluorescent colors, including yellow, red, and orange, in organic solutions of three solvents with different polarities (Table 2); -5 Compound 3m (at a concentration of 10 mol / L) exhibited distinctly different fluorescent colors, including yellow-green, non-fluorescent, and red, in organic solutions of three solvents with different polarities (Table 2); -5 The mol / L solution exhibited distinctly different fluorescent colors, including yellow, red, and orange, in organic solutions in three solvents with different polarities (Table 2).

[0141] Table 2. Polarity information of three organic solvents

[0142]

[0143] Similarly, through fluorescence emission spectra ( Figure 10 It was also found that compounds 3j, 3k, 3l, and 3m (at a concentration of 10) - 5 The maximum emission peak of the mol / L fluorescein (fluorescein) in organic solutions of three solvents with different polarities (Table 2) is located at different emission wavelengths and has different fluorescence intensities.

[0144] Therefore, compounds 3j, 3k, 3l, and 3m dissolve in organic solvents of different polarities at concentrations as low as 10. -5 At mol / L, fluorescence can rapidly exhibit distinctly different color responses with minute changes in polarity. This indicates that fluorescent molecules 3j, 3k, 3l, and 3m can serve as polar probes for visually identifying organic solvents of different polarities.

[0145] In summary, this invention modifies the 4 and 7 positions of 5,6-difluorobenzothiadiazole via a Sonogashira coupling reaction, using readily available compounds as starting materials to synthesize a novel panchromatic fluorescent molecule in one step. The reaction is easily controlled, the product purification is simple, and the yield is consistently above 60%. This invention synthesizes a panchromatic fluorescent molecule based on the difluorobenzothiadiazole fluorophore, and the synthesized fluorescent molecule exhibits a wide emission range (λ). em It exhibits fluorescence intensity (445-672 nm), variable fluorescence quantum yield (Φ = 83%-6%), and a large Stokes shift (66-155 nm), and demonstrates good response to organic solvents of varying polarities (such as n-hexane, dichloromethane, and 1,4-dioxane). Compared to conventional benzothiadiazole dyes, the fluorinated benzothiadiazole structure of this invention facilitates the Sonogashira coupling reaction, thereby increasing the yield, and also improves fluorescence intensity, fluorescence quantum yield, and fluorescence lifetime.

Claims

1. A difluorobenzothiadiazole fluorescent molecule, characterized in that, The difluorobenzothiadiazole fluorescent molecules are selected from compounds with the following structures: 、 、 、 、 、 、 、 、 、 。 2. The method for preparing the difluorobenzothiadiazole fluorescent molecule according to claim 1, characterized in that, The process includes the following steps: reacting 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole with a terminal alkyne to prepare the difluorobenzothiadiazole fluorescent molecule; wherein the terminal alkyne is selected from 1-hexyne, 2-acetylenthiophene, benzoyne, 4-tolylaceyne, 4-acetylenyl anisole, p-chlorophenylaceyne, 1-acetylenylnaphthalene, 4-acetylenyl biphenyl, 9-(4-acetylenylphenyl)carbazole, and 4-acetylenyltriphenylamine.

3. The method for preparing difluorobenzothiadiazole fluorescent molecules according to claim 2, characterized in that, The reaction involves the addition of a catalyst; the catalyst includes a palladium catalyst and a copper (I) salt.

4. The method for preparing difluorobenzothiadiazole fluorescent molecules according to claim 2, characterized in that, The molar ratio of the 4,7-dibromo-5,6-difluorobenzo[c][1,2,5]thiadiazole to the terminal alkyne is 1:(2~4).

5. The method for preparing difluorobenzothiadiazole fluorescent molecules according to any one of claims 2-4, characterized in that, The reaction is carried out at 110–130°C for 20–40 hours.

6. The application of the difluorobenzothiadiazole fluorescent molecule as described in claim 1 in the preparation of organic light-emitting materials, fluorescent dyes, or fluorescent probes.

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