Indolylbenzothiadiazole derivatives, organic fluorescent materials and cured films

Abstract

To provide a fluorescent organic molecule that has its emission intensity to change in response to mechanical stimulation and spontaneously returns to the original emission intensity at around the room temperature, an organic fluorescent material containing the fluorescent organic molecule and a cured product thereof.SOLUTION: The present invention discloses an indolylbenzothiadiazole derivative represented by formula (1) (where R1-R4 and R6-R8 each denote H or a specific substituent; R5 is an alkyl group substituted with one or more fluorine atoms; R9 is halogen, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amide group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group or an aryl group).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an indolylbenzothiadiazole derivative, an organic fluorescent material, and a cured film. [Background technology]

[0002] In recent years, there has been a gradual increase in reports on the phenomenon in which solid-state fluorescent organic molecules change their luminescence properties in response to mechanical stimulation and then return to their original luminescence properties. Most of these reports relate to mechanochromism, in which the luminescence color changes in response to mechanical stimulation. For example, Patent Documents 1 and 2 disclose solid-state fluorescent organic molecules that change their luminescence color in response to mechanical stimulation and then return to their original luminescence color.

[0003] Solid-state fluorescent organic molecules whose emission properties change upon application of mechanical stimuli usually require heating or exposure to solvent vapor to restore the original state, which is inconvenient, and only a limited number of fluorescent organic molecules exhibit high fluorescence quantum yields in the solid state.

[0004] Patent Document 3 reports a solid-state fluorescent organic molecule that can change its emission color in response to a mechanical stimulus and then spontaneously return to its original emission color at around room temperature, and that also exhibits a high fluorescence quantum yield in the solid state. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5697030 [Patent Document 2] International Publication No. 2012 / 039508 [Patent Document 3] Patent No. 6663820 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, most fluorescent organic molecules that change their emission characteristics in response to mechanical stimuli exhibit mechanochromism, which changes the emission color in response to mechanical stimuli, and there have been few reports of fluorescent organic molecules that change their emission intensity. If a fluorescent organic molecule is developed that can change its emission intensity in response to mechanical stimuli and then spontaneously return to its original intensity around room temperature, it is expected that the applications of organic fluorescent materials using such fluorescent organic molecules will be further expanded.

[0007] The present invention aims to provide a novel fluorescent organic molecule whose emission intensity changes in response to a mechanical stimulus and spontaneously returns to its original emission intensity at around room temperature. The present invention also aims to provide an organic fluorescent material containing the fluorescent organic molecule, and a cured product thereof. [Means for solving the problem]

[0008] According to a first aspect of the present invention, there is provided an indolylbenzothiadiazole derivative represented by the following formula (1): [ka]

[0009] In formula (1), R 1 ~R 4 , and R 6 ~R 8 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group; R 5 represents an alkyl group substituted with one or more fluorine atoms, R 9represents a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group.

[0010] In one embodiment, the indolylbenzothiadiazole derivative may be a compound represented by the following formula (2). [ka] In formula (2), R 5 and R 9 are R in the above formula (1), 5 and R 9 is synonymous with.

[0011] In another embodiment, R in the above formula (1) or the above formula (2) 5 may be an alkyl group having 4 or more carbon atoms substituted with one or more fluorine atoms.

[0012] In another embodiment, R in the above formula (1) or the above formula (2) 5 may be a perfluoroalkyl group.

[0013] In another embodiment, R in the above formula (1) or the above formula (2) 9 may be an alkyl group.

[0014] In another embodiment, R in the above formula (1) or the above formula (2) 9 may be a methyl group, an ethyl group, or an isopropyl group.

[0015] According to a second aspect of the present invention, there is provided an organic fluorescent material containing an indolylbenzothiadiazole derivative represented by the above formula (1) or (2).

[0016] In one embodiment, the organic fluorescent material is used as a fluorescent patterning material, a fluorescent switching material, or a fluorescent sensor material.

[0017] According to a third aspect of the present invention, there is provided a cured film made of the above organic fluorescent material. Effect of the Invention

[0018] The present invention makes it possible to provide a novel fluorescent organic molecule whose emission intensity changes in response to a mechanical stimulus and then spontaneously returns to its original emission intensity at around room temperature. The present invention also makes it possible to provide an organic fluorescent material containing the fluorescent organic molecule, and a cured film thereof. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a relative fluorescence spectroscopic diagram showing the change in luminescence intensity of the compound 1a according to this embodiment upon application of a mechanical stimulus. [Diagram 2] FIG. 2 is an image diagram showing the change in luminescence intensity of compound 1a according to this embodiment upon application of a mechanical stimulus. [Diagram 3] FIG. 3 is a relative fluorescence spectrum showing the change in emission intensity due to the application of a mechanical stimulus to a cured film A (thermocured film) containing the compound 1a according to this embodiment. [Figure 4] FIG. 4 is an image diagram showing the change in luminescence intensity due to the application of a mechanical stimulus to a cured film A (thermocured film) containing the compound 1a according to this embodiment. [Diagram 5] FIG. 5 is a relative fluorescence spectroscopic diagram showing the change in luminescence intensity due to the application of a mechanical stimulus to a cured film B (photocured film) containing the compound 1a according to this embodiment. [Figure 6] FIG. 6 is an image diagram showing the change in luminescence intensity due to the application of a mechanical stimulus to a cured film B (photocured film) containing compound 1a according to this embodiment. [Figure 7] FIG. 7 is a relative fluorescence spectroscopic diagram showing the fluorescence mechanochromism of the comparative compound 2a. [Figure 8] FIG. 8 is an image diagram showing the fluorescent mechanochromism of the comparative compound 2a. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] <Indolylbenzothiadiazole derivatives> A first embodiment of the present invention is an indolylbenzothiadiazole derivative represented by the following formula (1) (hereinafter referred to as "the indolylbenzothiadiazole derivative of the present invention"). [ka]

[0021] In formula (1), R 1 ~R 4 , and R 6 ~R 8 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group. R 5 represents an alkyl group substituted with one or more fluorine atoms. R 9 represents a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group.

[0022] The indolylbenzothiadiazole derivative of the present invention has a donor-acceptor structure in which an indolyl group as an electron-donating group and a benzothiadiazole group as an electron-withdrawing group are directly bonded via a single bond, and is an organic fluorescent molecule that exhibits fluorescence based on charge transfer from the electron-rich indolyl group to the electron-deficient benzothiadiazole ring. Various derivatives of the indolylbenzothiadiazole derivative of the present invention with different fluorescent emission colors can be easily synthesized simply by changing the substituents of the indole ring or the benzothiadiazole ring.

[0023] The indolylbenzothiadiazole derivative of the present invention exhibits a self-recovering luminescence characteristic in which the luminescence intensity changes due to mechanical stimulation (e.g., deformation due to physical force such as rubbing, etc.), and then returns to the original luminescence intensity simply by leaving it at room temperature. In contrast, the indolylbenzothiadiazole derivative disclosed in Patent Document 3 also exhibits a self-recovering luminescence characteristic, but the change in the luminescence characteristic due to mechanical stimulation is a change in the luminescence color due to the longer wavelength of the emission wavelength, which is different from the indolylbenzothiadiazole derivative of the present invention in which the luminescence intensity changes (becomes smaller). The mechanism of the above-mentioned change in luminescence characteristic exhibited by the indolylbenzothiadiazole derivative of the present invention in response to mechanical stimulation is speculated as follows. It will be explained in comparison with the indolylbenzothiadiazole derivative disclosed in Patent Document 3.

[0024] The following compound 1a (N-perfluorooctyl-3-methylindolylbenzothiadiazole) (see Example 1 below) is an indolylbenzothiadiazole derivative according to an embodiment of the present invention, and the following comparative compound 2a (N-Boc-3-methylindolylbenzothiadiazole) (see Comparative Example 1 below) is an indolylbenzothiadiazole derivative disclosed in Patent Document 3. Compound 1a and comparative compound 2a are represented by the formula (1) R 5 The corresponding substituents are perfluorooctyl (C8F 17 ), the latter being different in that it is a tert-butoxycarbonyl group (hereinafter referred to as a "Boc group"), but the other substituents are common to both.

[0025] [ka]

[0026] First, the powdered comparative compound 2a is an aggregate of microcrystals, and in the crystalline state, it has a structure in which two molecules are stacked (laminated) in an antiparallel manner at the benzothiadiazole ring sites. Comparative compound 2a has the characteristic of having a high quantum yield even in the solid state (no concentration quenching occurs), and this is presumably because the stacking structure between the two molecules suppresses stacking between multiple molecules.

[0027] Comparative compound 2a has a 3-position (R 9 ) has a methyl group, which acts as a steric hindrance to the benzothiadiazole ring located on the side, and the two benzothiadiazole rings are horizontally shifted and stacked (see

[0020] , FIG. 3, etc., of Patent Document 3). For this reason, the crystal structure of Comparative Compound 2a is unstable, and when mechanical stimulation is applied, the crystal structure collapses and becomes amorphous, and the emission wavelength becomes longer. Thereafter, it shows a reversible change in which it quickly returns to the crystalline state by self-recovery. In Comparative Compound 2a, the emission wavelength becomes longer as the crystal structure becomes amorphous in response to mechanical stimulation, which is thought to be because the intermolecular interaction between the heterocycles increases more than in the crystalline state, stabilizing the excited state. As demonstrated in Comparative Example 1 below, the emission intensity of Comparative Compound 2a does not change due to mechanical stimulation.

[0028] Compound 1a, which is an indolyl benthiadiazole derivative according to this embodiment, also has a structure in which a 3-position (R 9 ) has a methyl group, and in the crystalline state, the two benzothiadiazole rings are horizontally shifted and stacked. Therefore, the crystal structure of compound 1a according to this embodiment is also unstable, and it becomes amorphous upon mechanical stimulation, and then shows a reversible change in which it quickly returns to the crystalline state by self-recovery. However, as described above, unlike the comparative compound 2a, compound 1a shows the characteristic that the luminescence intensity is weakened by the crystal structure becoming amorphous in response to mechanical stimulation.

[0029] Although the mechanism is not entirely clear, the R group substituted on the nitrogen atom of the indole ring 5 When R is a fluorinated alkyl group (perfluorooctyl group), it is presumed that the molecular motion increases in the amorphous state, which leads to an increase in non-radiative deactivation. 5 In the case of fluoroalkyl groups, the interactions between the fluoroalkyl groups (such as aggregation) prevent intermolecular interactions between heterocycles, and the mobility of the molecule as a whole increases in the amorphous state. This increase in molecular mobility leads to an increase in non-radiative deactivation (loss of energy as heat), which is presumably the reason why the luminescence intensity decreases when the crystal structure becomes amorphous due to mechanical stimulation.

[0030] The above mentioned R 5 The interaction between fluorinated alkyl groups represented by the formula (I) is stronger as the number of carbon atoms increases. 5 The fluorinated alkyl group represented by the formula (I) is preferably a fluorinated alkyl group having 4 or more carbon atoms, and more preferably a fluorinated alkyl group having 6 or more carbon atoms. The upper limit of the number of carbon atoms is not particularly limited, but may be, for example, 12 or less. In the embodiment of the present invention, R 5 The fluorinated alkyl group represented by the formula (I) is preferably a perfluoroalkyl group.

[0031] In addition, for ease of dye synthesis, in the embodiment of the present invention, R 9 The above-mentioned substituent represented by the formula (I) is preferably an alkyl group, and specific preferred examples of the alkyl group include a methyl group, an ethyl group, and an isopropyl group.

[0032] In an embodiment of the present invention, the indolylbenzothiadiazole derivative represented by formula (1) may be an indolylbenzothiadiazole derivative represented by the following formula (2). [ka] In formula (2), R 5 and R 9are R in the above formula (1), 5 and R 9 The same applies to the preferred embodiments.

[0033] (Method of producing indolylbenzothiadiazole derivative) The indolylbenzothiadiazole derivative of the present invention can be produced, for example, by the following method. First, N-Boc-indole-2-boronic acid represented by the following formula (3) is reacted with bromobenzothiadiazole represented by the following formula (4) by a known method such as Suzuki-Miyaura cross-coupling reaction using a palladium catalyst to obtain N-Boc-indolylbenzothiadiazole represented by formula (5). Next, Boc removal is performed by a known method (see

[0041] of Patent Document 3) to obtain indolylbenzothiadiazole represented by formula (6). Next, a fluorinated alkyl group (R 5 By introducing the group) by alkylation reaction in a known manner, the indolylbenzothiadiazole derivative represented by formula (1) can be obtained. [ka]

[0034] In the above formulas (3) to (6), R 1 ~R 4 and R 6 ~R 9 are R in formula (1), 1 ~R 4 and R 6 ~R 9 is synonymous with.

[0035] <Organic fluorescent materials and cured films> In the second embodiment, the indolylbenzothiadiazole derivative of the present invention, which is an organic fluorescent dye, is mixed with other materials such as polymer materials and polymers, and can be used as an organic fluorescent material for various purposes. The organic fluorescent material containing the indolylbenzothiadiazole derivative of the present invention exhibits a luminescence characteristic in which the luminescence intensity decreases when a mechanical stimulus is applied in a solid or liquid state, and returns to the original luminescence intensity when left alone.

[0036] In addition, the indolylbenzothiadiazole derivative of the present invention can be used in various applications as a cured film made of the organic fluorescent material as the third embodiment. The form of the cured film is not particularly limited, and may be, for example, a heat-cured film or a photo-cured film.

[0037] Specifically, the organic fluorescent material or cured film according to this embodiment can be used in the following applications that utilize highly sensitive fluorescence detection. -Writable and erasable fluorescent memory material -Detection of partial strain in materials (can be used repeatedly as the luminescent color spontaneously returns to normal) Fluorescent patterning materials Fluorescent switching materials Fluorescent sensor materials EXAMPLES

[0038] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0039] Comparative Example 1: Synthesis of N-Boc-3-methylindolylbenzothiadiazole (comparative compound 2a) and its fluorescent mechanochromism The above-mentioned N-Boc-3-methylindolylbenzothiadiazole (comparative compound 2a) synthesized in Example 1 of Patent Document 3 (Japanese Patent No. 6663820) was synthesized according to the synthesis reaction formula shown below in a similar manner to the method described in the same Example. [ka]

[0040] The powder of comparative compound 2a was rubbed with a spatula to apply mechanical stimulation, and the fluorescent mechanochromism of the solid luminescent dye was confirmed. The luminescent color of comparative compound 2a changed from blue-green to yellow-green immediately after rubbing, and then spontaneously returned to the original luminescent color when left at room temperature for about 20 seconds. The measurement results for comparative compound 2a are shown in Figures 7 and 8.

[0041] Figure 7 shows the relative fluorescence spectrum of the comparative compound 2a as a solid luminescent dye under black light. From Figure 7, it was confirmed that the emission color of the comparative compound 2a shifted from blue-green (maximum wavelength: 486 nm) to yellow-green (maximum wavelength: 518 nm) immediately after rubbing, and then spontaneously returned to the original emission color after 10 minutes of being left at room temperature. It was also confirmed from Figure 7 that the emission intensity of the comparative compound 2a was almost unchanged before and after the application of mechanical stimulation.

[0042] Figure 8 shows the fluorescence mechanochromism of the comparative compound 2a as a solid luminescent dye. The area of ​​the powder of the comparative compound 2a surrounded by the dotted line in the left image of Figure 8 that was rubbed with a spatula changed color immediately after rubbing (center image), and the original luminescent color was already restored when it was left at room temperature for 20 seconds (right image).

[0043] Example 1: Synthesis of N-perfluorooctyl-3-methylindolylbenzothiadiazole 1a and its fluorescence properties <Synthesis> With reference to Example 2 (

[0041] ) of Patent Document 3 (Japanese Patent No. 6663820), the comparative compound 2a synthesized in Comparative Example 1 was de-Boc-converted to synthesize the compound 2b (4-(3-methyl-1H-indol-2-yl)-2,1,3-benzothiadiazole) shown below. Furthermore, the obtained 2b was reacted with heptadecafluoro-n-octyl iodide (2 equivalents) in DMF (dimethylformamide) at room temperature for 15 hours in the presence of 2 equivalents of sodium hydride to obtain the compound R in formula (1). 5The following compound 1a (N-perfluorooctyl-3-methylindolylbenzothiadiazole) having a perfluorooctyl group at the end was obtained in a yield of 19%. [ka]

[0044] The melting point and infrared absorption spectrum (KBr method) of compound 1a are shown below. 1 The results of H NMR spectrum and HRMS-ESI are shown. (i) Melting point: 106.3-108.1°C. (ii)IR(KBr):νmax 2927, 1533, 1459, 1370, 1328, 1255, 1213, 1149, 964, 813, 750, 653cm -1 . (iii) 1 H NMR(300MHz,CDCl3):δ 8.16 (dd, J = 8.8, 1.0 Hz, 1H), 7.94 (d, J = 7.0 Hz, 1H), 7.84 (d, J = 7.8 Hz, 1H), 7.71 (dd, J = 8.8, 7.0 Hz, 1H), 7.57 (d, J = 7.8 Hz, 1H), 7.53 (dt, J = 7.8, 1.0 Hz, 1H), 7.40 (dt, J = 7.8, 1.0 Hz, 1H), 2.04 (s, 3H) (ppm). (iv) HRMS-ESI(m / z):[M+H] + C 23 H 10 F 17 N3S calculated value, 684.0397; measured value, 684.0387.

[0045] <Fluorescence spectrum measurement> When the luminescence characteristics of compound 1a in the solid state were measured, it was found that it emitted light at a maximum emission wavelength of 485 nm in the solid state. Furthermore, when mechanical stimulation was applied by rubbing with a spatula, the luminescence color did not change, but the luminescence intensity decreased immediately after rubbing. After rubbing, the luminescence intensity spontaneously returned to its original value when left at room temperature for 2 minutes. The measurement results for compound 1a are shown in Figures 1 and 2.

[0046] Figure 1 shows the relative fluorescence spectrum of compound 1a as a solid-state luminescent dye under black light. It can be seen from Figure 1 that the luminescent color of compound 1a does not change when mechanical stimulation is applied, but the luminescence intensity decreases immediately after rubbing, and then when left at room temperature for 10 minutes, the luminescence intensity spontaneously returns to the original level.

[0047] Figure 2 is an image showing the change in luminescence intensity of compound 1a as a solid luminescent dye due to mechanical stimulation. The area of ​​compound 1a powder surrounded by a dotted line in the image on the left side of Figure 2 that was rubbed with a spatula changed color immediately after rubbing (center image), and it was confirmed that the original luminescence intensity had already returned when it was left at room temperature for 2 minutes (right image).

[0048] Example 2: 1 part by mass of compound 1a (N-perfluorooctyl-3-methylindolylbenzothiadiazole) obtained in Example 1, 10 parts by mass of polyvinyl alcohol (manufactured by Kuraray Co., Ltd.), and 90 parts by mass of water were mixed to prepare coating liquid A containing compound 1a. Coating liquid A was applied to a PET substrate and dried at 60°C to obtain cured film A having a thickness of 10 μm.

[0049] When the luminescence characteristics of cured film A were measured, it emitted light with a maximum emission wavelength of 473 nm. Furthermore, when mechanical stimulation was applied by rubbing the surface of cured film A with a spatula, the luminescence color did not change, but the luminescence intensity decreased immediately after rubbing, and then spontaneously returned to the original luminescence intensity when left at room temperature for about 10 minutes. The measurement results for cured film A are shown in Figures 3 and 4.

[0050] Figure 3 shows the relative fluorescence spectrum under black light of cured film A. It was confirmed from Figure 3 that the luminescent color of cured film A did not change when mechanical stimulation was applied, but the luminescent intensity decreased immediately after rubbing, and then spontaneously returned to the original luminescent intensity when left at room temperature for 10 minutes.

[0051] Figure 4 is an image showing the change in luminescence intensity due to mechanical stimulation of cured film A. In Figure 4, the image on the right shows that the luminescence intensity of the area surrounded by the dotted line in the image on the left, which is the area where the surface of cured film A was rubbed with a spatula, decreased immediately after rubbing.

[0052] Example 3: 5 parts by mass of compound 1a (N-perfluorooctyl-3-methylindolylbenzothiadiazole) obtained in Example 1, 99 parts by mass of 2-hydroxyethylacrylamide (manufactured by KJ Chemical Co., Ltd.), and 1 part by mass of Omnirad TPO H (manufactured by IGM Resins BV) as a photopolymerization initiator were mixed together to prepare coating liquid B containing compound 1a. Coating solution B is applied at a rate of 20 g / m 2 The coating was then irradiated with light to harden the coating, yielding a cured film B. At this time, ultraviolet light was used as the light, and the ultraviolet light was irradiated using a conveyor-type ultraviolet curing device with a high-pressure mercury lamp at an exposure dose of 300 mJ / cm. 2 So I went.

[0053] When the luminescence characteristics of cured film B were measured, it emitted light with a maximum emission wavelength of 495 nm. Furthermore, when mechanical stimulation was applied by rubbing the surface of cured film B with a spatula, the luminescence color did not change, but the luminescence intensity decreased immediately after rubbing, and then spontaneously returned to the original luminescence intensity when left at room temperature for about 10 minutes. The measurement results for cured film B are shown in Figures 5 and 6.

[0054] Figure 5 shows the relative fluorescence spectrum under black light of cured film B. As can be seen from Figure 5, the luminescent color of cured film B does not change when mechanical stimulation is applied, but the luminescence intensity decreases immediately after rubbing, and then when left at room temperature for 10 minutes, the luminescence intensity spontaneously returns to its original level.

[0055] Moreover, Fig. 6 is an image showing the change in luminescence intensity due to mechanical stimulation of cured film B. In Fig. 6, it can be seen from the image on the right that the luminescence intensity of the part surrounded by the dotted line in the image on the left, which is the part where the surface of cured film B was rubbed with a spatula, decreased immediately after rubbing.

[0056] From the above Examples 2 and 3, it was confirmed that even in the cured film containing the solid fluorescent dye 1a, the emission intensity changes due to a mechanical stimulus, and then the emission characteristics change to spontaneously return to the original emission intensity.

[0057] The present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the gist of the present invention. The embodiments may be combined as appropriate, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention.

Claims

1. An indolylbenzothiadiazole derivative represented by the following formula (1): 【Chemistry 1】 In formula (1), R １ ~R ４ , and R ６ ~R ８ each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group; R ５ represents an alkyl group substituted with one or more fluorine atoms, R ９ represents a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group.

2. An indolylbenzothiadiazole derivative represented by the following formula (2): 【Chemistry 2】 In formula (2), R ５ represents an alkyl group substituted with one or more fluorine atoms, R ９ represents a halogen atom, a hydroxy group, an alkoxy group, an aralkyloxy group, an aryloxy group, a nitro group, an amino group, an amido group, a carboxy group, an alkyloxycarbonyl group, an aryloxycarbonyl group, a formyl group, a cyano group, an alkyl group, a cycloalkyl group, an aralkyl group, or an aryl group.

3. R in the formula (1) or (2) ５ The indolylbenzothiadiazole derivative according to claim 1 or 2, wherein is an alkyl group having 4 or more carbon atoms substituted with one or more fluorine atoms.

4. R in the formula (1) or (2) ５ The indolylbenzothiadiazole derivative according to any one of claims 1 to 3, wherein is a perfluoroalkyl group.

5. R in the formula (1) or (2) ９ The indolylbenzothiadiazole derivative according to any one of claims 1 to 4, wherein is an alkyl group.

6. R in the formula (1) or (2) ９ The indolylbenzothiadiazole derivative according to any one of claims 1 to 5, wherein is a methyl group, an ethyl group or an isopropyl group.

7. An organic fluorescent material comprising the indolylbenzothiadiazole derivative according to any one of claims 1 to 6.

8. The organic fluorescent material according to claim 7, which is used as a fluorescent patterning material, a fluorescent switching material or a fluorescent sensor material.

9. A cured film comprising the organic fluorescent material according to claim 7 or 8.

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