Fluorene derivative as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of stimuli-responsive materials, and particularly relates to a fluorene derivative as well as a preparation method and application thereof. The structural formula of the fluorene derivative is as shown in formula I. The fluorene derivative disclosed by the invention has a high-contrast three-color force-induced fluorescence discoloration property. The fluorescent powder has a green fluorescence emission characteristic under a room temperature condition, and the color of the fluorescent powder can be obviously changed when the fluorescent powder is subjected to different degrees of mechanical force. Specifically, after slight grinding treatment, the color of the fluorene derivative is changed from green to yellow, and the fluorene derivative emits light; and the heavy grinding operation is continued, the color is further converted from yellow to red to emit light, and the color can be recovered to the initial green under the fumigation of dichloromethane gas, so that the high-contrast three-color force-induced fluorescence discoloration is realized. Due to the unique property, the fluorene derivative has a wide application prospect in the fields of information encryption anti-counterfeiting technology, high-precision sensors, intelligent display equipment and the like. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of stimulus responsive materials, and in particular relates to a fluorene derivative and a preparation method and application thereof. Background Art

[0002] In today's era of rapid technological development, the research and development of stimulus-responsive materials has become one of the hot areas of scientific research. Among them, fluorene derivatives, as an important class of organic compounds, have attracted widespread attention due to their unique structure and excellent physical and chemical properties. Fluorene and its derivatives have a rigid planar biphenyl structure and a large π conjugated system, which endows them with unique photoelectric properties and biological activities, making them show broad application prospects in the fields of mechanochromic materials, two-photon absorption materials, photochromic materials, and organic electroluminescent materials.

[0003] High-contrast three-color mechanofluorescence color-changing properties refer to three-color mechanofluorescence color-changing properties with obvious fluorescence color contrast that can be observed by the naked eye, but current fluorene derivatives cannot achieve high-contrast three-color mechanofluorescence color-changing properties. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a fluorene derivative and a preparation method and application thereof. The fluorene derivative provided by the present invention has a high-contrast three-color force-induced fluorescence color change property.

[0005] The present invention provides a fluorene derivative, the structural formula of which is shown in Formula I:

[0006]

[0007] The present invention also provides a method for preparing the fluorene derivative described in the above technical solution, comprising the following steps:

[0008] Under a protective atmosphere, dibromofluorene having a structure shown in Formula II, 4-triphenylamine borate, a first organic palladium catalyst and a first organic solvent are mixed to perform a first Suzuki coupling reaction to obtain the fluorene derivative;

[0009]

[0010] Preferably, the molar ratio of dibromofluorene having the structure shown in Formula II to 4-triphenylamine borate is 1:2.2 to 1:2.4.

[0011] Preferably, the temperature of the first Suzuki coupling reaction is 80-100° C., and the time is 12-24 hours.

[0012] Preferably, the first organopalladium catalyst comprises Pd(PPH 3 ) 4 or Pd(OAc)2 .

[0013] Preferably, the first organic solvent includes one or more of tetrahydrofuran, dioxane, acetonitrile, methanol, and ethanol.

[0014] Preferably, the dibromoarenofluorene having the structure shown in Formula II is prepared by a method including the following steps:

[0015] Under a protective atmosphere, 2,7-dibromo-9-fluorenone, p-methoxyphenylboronic acid, a second organopalladium catalyst, and a second organic solvent are mixed to carry out a second Suzuki coupling reaction to obtain 2,7-bis(4-methoxyphenyl)-fluorenone having the structure shown in Formula III;

[0016] Under a protective atmosphere, the 2,7-bis(4-methoxyphenyl)-fluorenone having the structure shown in Formula III, carbon tetrabromide, triphenylphosphine, and a third organic solvent are mixed to carry out a Darzens-Fuchs reaction to obtain the dibromoarenofluorene having the structure shown in Formula II;

[0017]

[0018] Preferably, the molar ratio of 2,7-dibromo-9-fluorenone to p-methoxyphenylboronic acid is 1:2.2 to 1:2.4; the temperature of the second Suzuki coupling reaction is 80 to 100 °C, and the time is 12 to 24 hours.

[0019] Preferably, the molar ratio of 2,7-bis(4-methoxyphenyl)-fluorenone, carbon tetrabromide, and triphenylphosphine having the structure shown in Formula III is 1:2 to 3:4 to 5.

[0020] The present invention also provides an application of the fluorene derivative described in the above technical solution in the fields of anti-counterfeiting, sensors, or intelligent displays.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a fluorene derivative, the structural formula of which is shown in Formula I. The fluorene derivative provided by the present invention contains a fluorene unit and two triphenylamine units, which contribute to the high-brightness solid-state fluorescence and force-tunable conformational change characteristics of the substance. In addition, the fluorene derivative also has two methoxyphenyl groups, which is beneficial to the formation of intermolecular C-H...O hydrogen bonds, and finally enables the fluorene derivative to have high-contrast three-color force-induced fluorescence color change properties. The fluorene derivative of the present invention exhibits green fluorescence emission characteristics at room temperature, and its color will change significantly when subjected to mechanical forces of different degrees. Specifically, after mild grinding treatment, the color of the fluorene derivative changes from green to yellow emission; and when continuing with severe grinding operation, the color further changes from yellow to red emission, and it can be restored to the original green under the fumigation of dichloromethane gas, that is, a high-contrast green-to-yellow-to-red three-color force-induced fluorescence color change is achieved.

[0023] The fluorene derivative of the present invention has force-induced gradually red-shifted fluorescence color change characteristics, with three significantly contrasting fluorescence color changes from green to yellow to red, that is, it has high-contrast three-color force-induced fluorescence color change properties. This unique property enables the fluorene derivative to show broad application prospects in the fields of information encryption and anti-counterfeiting technology, high-precision sensors, and intelligent display devices, etc. Brief Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is the solid fluorescence emission spectrum of the fluorene derivative prepared in Example 1 at room temperature. Detailed Embodiments

[0026] The present invention provides a fluorene derivative, the structural formula of which is shown in Formula I:

[0027]

[0028] The fluorene derivative of the present invention has three-color force-induced fluorescence color change properties and is a fluorene derivative with high-contrast three-color force-induced fluorescence color change that gradually red-shifts under mild grinding and strong grinding.

[0029] The present invention also provides a preparation method of the fluorene derivative described in the above technical solution, including the following steps:

[0030] Under a first protective atmosphere, dibromoarenofluorene having the structure shown in Formula II, 4-borotriphenylamine, a first organic palladium catalyst, and a first organic solvent are mixed to carry out a first Suzuki coupling reaction to obtain the fluorene derivative;

[0031]

[0032] In the present invention, unless otherwise specified, the materials and equipment used are all commercially available products in the art.

[0033] In the present invention, the first protective atmosphere is preferably an argon atmosphere.

[0034] In the present invention, the molar ratio of dibromoarenofluorene having the structure shown in Formula II to 4-borotriphenylamine is preferably 1:2.2 to 1:2.4, more preferably 1:2.2.

[0035] In the present invention, the first organic palladium catalyst preferably includes Pd(PPH 3 ) 4 or Pd(OAc) 2 (palladium acetate), and the first organic palladium catalyst is preferably 1% to 10% of the molar amount of dibromoarenofluorene having the structure shown in Formula II.

[0036] In the present invention, the first organic solvent preferably includes one or more of tetrahydrofuran, dioxane, acetonitrile, methanol, and ethanol, and the first organic solvent is a polar organic solvent. The dosage ratio of dibromoarenofluorene having the structure shown in Formula II to the first organic solvent is preferably 1.82 mmol:(30 - 40) mL.

[0037] In the present invention, when the dibromoarenofluorene having the structure shown in Formula II, 4-borotriphenylamine, the first catalyst, and the first organic solvent are mixed, an aqueous solution of an alkali metal carbonate is preferably added; the aqueous solution of the alkali metal carbonate preferably includes an aqueous solution of sodium carbonate or an aqueous solution of potassium carbonate; the concentration of the aqueous solution of the alkali metal carbonate is preferably 2 mol / L, and the volume ratio of the first organic solvent to the aqueous solution of the alkali metal carbonate is preferably 2:1.

[0038] In the present invention, the temperature of the first Suzuki coupling reaction is preferably 80 - 100 °C, and the time is preferably 12 - 24 hours; the first Suzuki coupling reaction is preferably carried out under reflux stirring. Taking the first organic solvent as tetrahydrofuran, the alkali metal carbonate as potassium carbonate, and the first organic palladium catalyst as Pd(PPH 3 ) 4 as an example, the reaction formula for preparing the fluorene derivative by the Suzuki coupling reaction of dibromoarenofluorene having the structure shown in Formula II and 4-borotriphenylamine is shown as follows:

[0039]

[0040] The present invention prepares a fluorene derivative by carrying out a Suzuki coupling reaction on dibromoalkenylfluorene having the structure shown in Formula II and 4-borotriphenylamine under the catalysis of Pd(PPH 3 ) 4 , and the yield of the fluorene derivative is high.

[0041] In the present invention, preferably after the first Suzuki coupling reaction, it further includes: cooling the obtained reaction solution to room temperature, extracting it three times with dichloromethane, drying the organic phase with anhydrous Na 2 SO 4 , spinning off the solvent, and separating by column chromatography. Preferably, after the extraction, the obtained organic phase is first washed three times with saturated brine; the time for drying with anhydrous Na 2 SO 4 is preferably 3 hours; the column chromatography separation preferably uses a silica gel column with 200 - 300 meshes, the eluent for the column chromatography separation is preferably a mixed solvent of petroleum ether and dichloromethane, and the volume ratio of petroleum ether to dichloromethane is preferably 3:1.

[0042] In the present invention, the dibromoalkenylfluorene having the structure shown in Formula II is preferably prepared by a method including the following steps:

[0043] Under a second protective atmosphere, 2,7-dibromo-9-fluorenone, p-methoxyphenylboronic acid, a second organopalladium catalyst, and a second organic solvent are mixed to carry out a second Suzuki coupling reaction to obtain 2,7-bis(4-methoxyphenyl)-fluorenone having the structure shown in Formula III;

[0044] Under a third protective atmosphere, the 2,7-bis(4-methoxyphenyl)-fluorenone having the structure shown in Formula III, carbon tetrabromide, triphenylphosphine, and a third organic solvent are mixed to carry out a Darey-Fuchs reaction to obtain dibromoalkenylfluorene having the structure shown in Formula II;

[0045]

[0046] The second protective atmosphere is preferably an argon atmosphere.

[0047] The molar ratio of 2,7-dibromo-9-fluorenone to p-methoxyphenylboronic acid is preferably 1:2.2 - 1:2.4, and more preferably 1:2.2.

[0048] The second organopalladium catalyst preferably includes Pd(PPH 3 ) 4 or Pd(OAc) 2 .

[0049] The second organic solvent preferably includes one or more of tetrahydrofuran, dioxane, acetonitrile, methanol, and ethanol.

[0050] When the 2,7-dibromo-9-fluorenone, p-methoxyphenylboronic acid, the second organopalladium catalyst, and the second organic solvent are mixed, an aqueous solution of an alkali metal carbonate is preferably added; the aqueous solution of the alkali metal carbonate preferably includes an aqueous sodium carbonate solution or an aqueous potassium carbonate solution; the concentration of the aqueous solution of the alkali metal carbonate is preferably 2 mol / L, and the volume ratio of the second organic solvent to the aqueous solution of the alkali metal carbonate is preferably 5:3.

[0051] The temperature of the second Suzuki coupling reaction is preferably 80 to 100 °C, and the time is preferably 12 to 24 hours. Taking tetrahydrofuran as the second organic solvent, potassium carbonate as the alkali metal carbonate, and Pd(PPH 3 ) 4 as an example, the reaction formula of the second Suzuki coupling reaction is shown as follows:

[0052]

[0053] After the second Suzuki coupling reaction, it preferably further includes: cooling the obtained reaction solution to room temperature, extracting three times with dichloromethane, drying the organic phase with anhydrous Na 2 SO 4 , spinning out the solvent, and performing column chromatography separation. After the extraction, the obtained organic phase is preferably washed three times with saturated brine; the drying time with anhydrous Na 2 SO 4 is preferably 3 hours; the column chromatography separation preferably uses a silica gel column with 200 to 300 meshes, the eluent for the column chromatography separation is preferably a mixed solvent of petroleum ether and dichloromethane, and the volume ratio of petroleum ether to dichloromethane is preferably 4:1.

[0054] The molar ratio of 2,7-bis(4-methoxyphenyl)-fluorenone having the structure shown in Formula III, carbon tetrabromide, and triphenylphosphine is 1:2 to 3:4 to 5, more preferably 1:2:4.

[0055] The third protective atmosphere is preferably an argon atmosphere.

[0056] The third organic solvent preferably includes dichloromethane.

[0057] The temperature of the Darey-Fuchs reaction is preferably 40 to 50 °C, and the time is preferably 24 to 30 hours. The Darey-Fuchs reaction is preferably carried out under reflux stirring. Taking dichloromethane as the organic solvent as an example, during the reflux stirring process, one-carbon homologation occurs to generate dibromoolefin (dibromoolefin fluorene), and the reaction formula is shown as follows:

[0058]

[0059] After the Darey-Fuchs reaction, it preferably further includes: cooling the obtained reaction solution to room temperature, extracting it three times with dichloromethane, and drying the organic phase with anhydrous Na 2 SO 4 , spinning off the solvent, and separating by column chromatography. After the extraction, it is preferably to wash the obtained organic phase three times with saturated brine first; the drying time with anhydrous Na 2 SO 4 is preferably 3 hours; the column chromatography separation preferably uses a silica gel column with 200 - 300 meshes, the eluent for the column chromatography separation is preferably a mixed solvent of petroleum ether and dichloromethane, and the volume ratio of petroleum ether to dichloromethane is preferably 6:1.

[0060] The present invention also provides the application of the fluorene derivative described in the above technical solution in the fields of anti-counterfeiting, sensors or intelligent displays.

[0061] In the present invention, the anti-counterfeiting includes anti-counterfeiting information encryption, different color states represent different data bits, making information encryption labels, and transmitting hidden information according to color changes to achieve anti-counterfeiting data encryption.

[0062] The fluorene derivative of the present invention has high-contrast three-color mechanochromic fluorescence properties, exhibits green fluorescence emission characteristics at room temperature, turns from green to yellow luminescence after mild grinding treatment; continuing with severe grinding operation, the color further changes from yellow to red luminescence, and returns to the original green under the fumigation (30 seconds to 1 minute) of dichloromethane gas.

[0063] To further illustrate the present invention, the fluorene derivative provided by the present invention, its preparation method and application will be described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the protection scope of the present invention.

[0064] Example 1

[0065] Synthesize a fluorene derivative with high-contrast three-color mechanochromic fluorescence properties according to the following reaction route:

[0066]

[0067] In the reaction formula, THF - tetrahydrofuran; K 2 CO 3 - potassium carbonate; CH 2 Cl 2 - dichloromethane; PPH 3 - triphenylphosphine; CBr 4 - carbon tetrabromide.

[0068] The specific synthesis steps are as follows:

[0069] 1. At room temperature, 4 g (11.84 mmol, formula 1-1) of 2,7-dibromo-9-fluorenone and 3.96 g (26.04 mmol) of p-methoxyphenylboronic acid were added into a 250 mL three-necked flask. After adding 100 mL of tetrahydrofuran solvent, 60 mL of 2 mol / L -1 aqueous potassium carbonate solution was added. After evacuating the air, the protective gas (argon) was filled and the operation was cycled three times. After the protective gas was filled for the last time, 1% of the molar amount of 2,7-dibromo-9-fluorenone of Pd(PPH 3 ) 4 catalyst was added. After evacuating the air again, the protective gas was filled and the operation was cycled three times. The mixture was refluxed and stirred at 80 °C for 12 hours. After the reaction was completed and the temperature dropped to room temperature, the mixture in the three-necked flask was transferred to a rotary evaporation flask. After evaporation to dryness, it was transferred to a separatory funnel with dichloromethane, washed three times with saturated brine, and extracted three times with dichloromethane. The obtained organic phase was dried with anhydrous Na 2 SO 4 for 3 hours. The dichloromethane solvent was evaporated, and silica gel column chromatography was used for separation (the eluent was a mixed solvent of petroleum ether and dichloromethane, with a volume ratio of 4:1) to obtain 2.35 g of compound 1-2, and the yield was 76%.

[0070] 2. At room temperature, 2.5 g (6.37 mmol) of the compound 1-2 prepared in the previous step, 4.22 g (12.74 mmol) of carbon tetrabromide and 6.68 g (25.48 mmol) of triphenylphosphine were added into a 250 mL three-necked flask. 130 mL of dichloromethane solvent was added. After evacuating the air, the protective gas (argon) was filled and the operation was cycled three times. The mixture was refluxed and stirred at 40 °C for 24 hours. After the reaction was completed and the temperature dropped to room temperature, the mixture in the three-necked flask was transferred to a rotary evaporation flask. After evaporation to dryness, it was transferred to a separatory funnel with dichloromethane, washed three times with saturated brine, and extracted three times with dichloromethane. The obtained organic phase was dried with anhydrous Na 2 SO 4 for 3 hours. The solvent was evaporated to dryness, and silica gel column chromatography was used for separation (the eluent was a mixed solvent of petroleum ether and dichloromethane, with a volume ratio of 6:1) to obtain 2.0 g of product 1-3, and the yield was 57%.

[0071] 3. At room temperature, 1 g (1.82 mmol) of the compound 1-3 prepared in the previous step and 1.16 g (4.00 mmol) of 4-(diphenylphosphino)phenylboronic acid were added into a 100 mL three-necked flask. After adding 40 mL of tetrahydrofuran solvent, 20 mL of 2 mol / L -1 aqueous potassium carbonate solution was added. After evacuating the air, the protective gas (argon) was filled and the operation was cycled three times. After the protective gas was filled for the last time, 1% of the molar amount of compound 1-3 of Pd(PPH 3 ) 4The catalyst was continuously evacuated and then filled with a protective gas for three cycles of operation. The reaction was refluxed and stirred at 80 °C for 12 hours. After the reaction ended and the temperature dropped to room temperature, the mixture in the three-necked flask was transferred to a rotary evaporation flask. After rotary evaporation to dryness, it was transferred to a separatory funnel with dichloromethane, washed three times with saturated brine, and extracted three times with dichloromethane. The obtained organic phase was dried with anhydrous Na 2 SO 4 for 3 hours. The dichloromethane solvent was rotary-evaporated off, and the product fluorene derivative (Formula I) was obtained by silica gel column chromatography (the eluent was a mixed solvent of petroleum ether and dichloromethane with a volume ratio of 3:1), with a yield of 71% and a mass of 1.12 g.

[0072] The NMR data are as follows: 1 HNMR (500 MHz, CDCl 3 ): δ (ppm) = 7.76 (d, J = 5.0 Hz, 2H), 7.48 (d, J = 5.0 Hz, 2H), 7.41 (d, J = 10.0 Hz, 4H), 7.30 (d, J = 5.0 Hz, 4H), 7.23 (t, J = 10.0 Hz, 10H), 7.14 (d, J = 10.0 Hz, 8H), 7.09 (d, J = 10.0 Hz, 4H), 7.04 (t, J = 7.5 Hz, 4H), 6.98 (d, J = 10 Hz, 4H), 3.84 (s, 6H).

[0073] 13 C NMR (125 MHz, CDCl 3 ): δ (ppm) = 158.9, 148.2, 147.3, 146.1, 140.0, 138.5, 138.4, 136.1, 134.3, 133.4, 131.7, 129.4, 127.9, 125.7, 125.0, 123.4, 123.2, 122.2, 119.5, 114.1, 55.3.

[0074] The solid fluorescence emission spectrum of the fluorene derivative product prepared in Example 1 at room temperature is as shown in Figure 1As shown, it includes solid samples, slightly ground samples, heavily ground samples, and samples fumigated with dichloromethane vapor after heavy grinding at room temperature and under 365 nm ultraviolet light irradiation. It can be seen that the fluorescence emission peak of the fluorene derivative product is located at about 510 nm, and significant green fluorescence can be observed under 365 nm ultraviolet light irradiation; subsequently, the product is slightly ground (the product is gently pressed with a grinding rod), and the emission peak undergoes a red shift (from about 510 nm to about 555 nm), and the fluorescence color changes to yellow; further, the product is heavily ground (2 - 4 GPa), and the fluorescence of the product changes from yellow to red during this process, and the emission peak undergoes a red shift (from about 555 nm to about 640 nm). In addition, fumigating with dichloromethane (DCM) vapor (for 30 seconds) restores the heavily ground state to the initial unground state, showing high-contrast three-color mechanochromic fluorescence properties.

[0075] Example 2

[0076] The difference from Example 1 is that the Pd(PPH 3 ) 4 catalyst in Step 3 is replaced with palladium acetate, and the remaining steps are the same. The yield of the final product, fluorene derivative (Formula I), is 40%.

[0077] The product prepared by the present invention is a fluorene derivative with high-contrast three-color mechanochromic fluorescence properties, and has broad application prospects in the fields of anti-counterfeiting information encryption, high-precision sensors, and smart display device materials, etc.; this characteristic makes it particularly suitable for the field of anti-counterfeiting information encryption technology, where different color states represent different data bits, making information encryption labels, and transmitting hidden information according to color changes to achieve anti-counterfeiting data encryption.

[0078] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments according to the embodiments of the present invention without creative labor, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A fluorene derivative, characterized in that: The structural formula is shown in Formula I:

2. The method for preparing a fluorene derivative according to claim 1, characterized in that: The following steps are involved: Under a protective atmosphere, dibromofluorene having a structure shown in Formula II, 4-triphenylamine borate, a first organic palladium catalyst and a first organic solvent are mixed to perform a first Suzuki coupling reaction to obtain the fluorene derivative; 3. The preparation method according to claim 2, characterized in that: The molar ratio of dibromofluorene having the structure shown in formula II to 4-triphenylamine borate is 1:2.2 to 1:2.

4.

4. The preparation method according to claim 2 or 3, characterized in that: The temperature of the first Suzuki coupling reaction is 80-100° C., and the time is 12-24 hours.

5. The preparation method according to claim 2, characterized in that: The first organic palladium catalyst includes Pd(PPH3)4 or Pd(OAc)2.

6. The preparation method according to claim 2, characterized in that: The first organic solvent includes one or more of tetrahydrofuran, dioxane, acetonitrile, methanol and ethanol.

7. The preparation method according to claim 2, characterized in that: The dibromofluorene having the structure shown in formula II is prepared by a method comprising the following steps: Under a protective atmosphere, 2,7-dibromo-9-fluorenone, p-methoxyphenylboronic acid, a second organic palladium catalyst and a second organic solvent are mixed to perform a second Suzuki coupling reaction to obtain 2,7-di(4-methoxyphenyl)-fluorenone having a structure shown in Formula III; Under a protective atmosphere, the 2,7-di(4-methoxyphenyl)-fluorenone having a structure shown in Formula III, carbon tetrabromide, triphenylphosphine and a third organic solvent are mixed to perform a Darey-Fuchs reaction to obtain a dibromofluorene having a structure shown in Formula II; 8. The preparation method according to claim 7, characterized in that: The molar ratio of the 2,7-dibromo-9-fluorenone to p-methoxyphenylboronic acid is 1:2.2 to 1:2.4; the temperature of the second Suzuki coupling reaction is 80 to 100° C., and the time is 12 to 24 hours.

9. The preparation method according to claim 7, characterized in that: The molar ratio of 2,7-di(4-methoxyphenyl)-fluorenone having a structure shown in formula III, carbon tetrabromide and triphenylphosphine is 1:2-3:4-5.

10. Use of the fluorene derivative according to claim 1 in the fields of anti-counterfeiting, sensors or intelligent displays.

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