Azobenzene dual-mode photochromic compound as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic optical functions, in particular to an azobenzene dual-mode photochromic compound as well as a preparation method and application thereof. The compound has a structure as shown in (I): # imgabs0 #. The azobenzene dual-mode photochromic compound prepared by the invention has extremely fast photoresponse capability, can realize the dual-mode photochromic phenomenon of color and fluorescence, realizes the conversion of color from yellow to colorless and the conversion of fluorescence from non-fluorescence to blue fluorescence under the irradiation of ultraviolet light, and has large optical property change before and after photochromic, so that the photochromic effect is good. The color contrast ratio is high, and high definition of information storage is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of organic photofunctional technology, and more specifically to an azobenzene dual-mode photochromic compound and a preparation method and application thereof. Background Art

[0002] Photochromic compounds are substances whose structure or conformation can undergo reversible changes under the action of light of a specific wavelength, and this change will cause macroscopic changes in their color, fluorescence and other physical properties. Due to their high modifiability, fast response speed, remote controllability and rich color changes, these compounds have been widely used in intelligent fields such as information storage, encryption and anti-counterfeiting, optical switches, and optical coding.

[0003] As the research on photochromic materials continues to deepen, researchers have developed a variety of compound systems, including more than ten types such as diarylethenes, spiropyrans, fulgides, and azobenzenes. In particular, azobenzene photochromic materials have developed rapidly due to their high optical activity, reversible color change process and simple synthesis method. Azobenzene compounds contain nitrogen-nitrogen double bonds and have cis-trans geometric isomers. Normally, azobenzene substances exist in a stable trans structure, but under external stimuli such as light, a transition from trans to cis can occur. Cis azo compounds are in a metastable state and can be restored to the trans conformation under heating or light conditions.

[0004] However, most of the azobenzene photochromic materials studied so far only show a single color change, which makes it difficult to meet the multidimensional requirements of multifunctional material design. In contrast, new luminescent materials with multi-mode responses show higher safety and complexity. Therefore, it is particularly important to develop dual-mode color-changing materials that can achieve both color and fluorescence responses. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one aspect of the present invention is to provide an azobenzene dual-mode photochromic compound having a structure shown in (I): .

[0006] Another aspect of the present invention is to provide a method for preparing an azobenzene dual-mode photochromic compound, wherein the preparation method comprises the following specific steps: S1. Add the reactants 2-bromothiophene, (4-aminophenyl)boric acid, tetrakis(triphenylphosphine)palladium, anhydrous potassium carbonate and tetrabutylammonium bromide to a double-necked round-bottom flask, add a solvent, and reflux and stir under nitrogen atmosphere to obtain solution A. After purifying solution A, a compound represented by structural formula (II) is obtained. ; S2. Add the compound of structural formula (II) into the solvent, add a cold aqueous solution of sodium nitrate dropwise, and continue stirring until the temperature reaches room temperature. Then add sodium carbonate and 2-aminobenzothiazole, and continue stirring to obtain solution B. After purification of solution B, the compound represented by structural formula (I) is obtained.

[0007] Preferably, the molar ratio of 2-bromothiophene, (4-aminophenyl)boric acid, tetrakis(triphenylphosphine)palladium, anhydrous potassium carbonate and tetrabutylammonium bromide in S1 is 1:1.2:0.05:5:0.01; the solvent is tetrahydrofuran and deionized water in a volume ratio of 5:1; the molar ratio of the reactant to the solvent is 1:100; and the reflux stirring time is 8 hours.

[0008] Preferably, the purification in S1 is that after the stirring is completed, solution A is cooled to room temperature, the reaction liquid is extracted with a saturated sodium chloride solution and dichloromethane, the organic phase is dried with anhydrous magnesium sulfate, the solvent is removed by a reduced pressure rotary evaporator, and finally, silica gel column chromatography is performed with petroleum ether and ethyl acetate as eluents; the volume ratio of petroleum ether to ethyl acetate is 5:1, the evaporation pressure of the reduced pressure rotary evaporator is 0.08 MPa, the evaporation temperature is 40°C, and the evaporation time is 0.5 h.

[0009] Preferably, the solvent in S2 is dilute hydrochloric acid and ice water in a volume ratio of 5:1; the concentration of the sodium nitrate solution is 0.2 mol / L, and the stirring time after addition is 20 min; the molar ratio of the compound (II), sodium nitrate, sodium carbonate and 2-aminobenzothiazole is 1:1:1:1, and the stirring time after addition is 20 min; the molar ratio of the compound of structural formula (II) to the solvent is 1:100.

[0010] Preferably, the purification in S2 is to add an excess of sodium chloride solution after stirring, filter it, rinse the obtained precipitate with ice water for multiple times and dry it in a vacuum drying oven, and finally perform neutral alumina column chromatography separation using petroleum ether and ethyl acetate as eluents; the volume ratio of petroleum ether and ethyl acetate is 10:1, the evaporation pressure of the reduced pressure rotary evaporator is 0.08 MPa, the evaporation temperature is 40°C, and the evaporation time is 0.5h.

[0011] Preferably, the synthetic route of the preparation method is as follows: .

[0012] Another aspect of the present invention is to provide an application of an azobenzene dual-mode photochromic compound, and application of the compound in information storage.

[0013] Preferably, the specific steps of applying the compound are as follows: S1. Mix the compound acetone solution and PMMA tetrahydrofuran solution evenly; S2. Spread the mixed solution evenly on a smooth quartz plate and store it away from light after drying.

[0014] Preferably, the concentration of the compound acetone solution in S1 is 1 mM, and the concentration of the PMMA tetrahydrofuran solution is 10 wt %; the volume ratio of the compound solution to the PMMA solution is 1:2; the mixing method is ultrasonic dispersion for 30 min; the mixed solution in S2 is 1 mL; the quartz plate is 3 cm×3 cm; and the drying method is drying in a vacuum drying oven at 40° C. for 2 h.

[0015] The beneficial effects of the present invention are as follows: The azobenzene dual-mode photochromic compound prepared by the present invention has a mature preparation method, mild reaction conditions, low cost of required raw materials, stable properties, and is suitable for commercial applications.

[0016] The azobenzene dual-mode photochromic compound prepared by the present invention has extremely fast light response ability, can realize dual-mode photochromic phenomenon of color and fluorescence, realizes the transformation of color from yellow to colorless and fluorescence from no fluorescence to blue fluorescence under the irradiation of ultraviolet light, the optical property changes greatly before and after photochromism, the color contrast is high, and the high definition of information storage is guaranteed.

[0017] The azobenzene dual-mode photochromic compound prepared by the present invention can realize multiple reversible and repeated color changes under the alternating irradiation of ultraviolet light and visible light. Combining the prepared azobenzene dual-mode photochromic compound with a polymer can realize erasable optical information storage.

[0018] Additional aspects and advantages of the invention will become apparent from the following description, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the intermediate product of the compound of structural formula (II) in Example 1 of the present invention; Figure 2 This is a hydrogen nuclear magnetic resonance spectrum of the azobenzene dual-mode photochromic compound of Example 1 of the present invention; Figure 3 It is the absorption spectrum of the diazobenzene dual-mode photochromic compound of the embodiment of the present invention before and after ultraviolet light irradiation and the change diagram under fluorescent light; Figure 4The fluorescence spectrum of the azobenzene dual-mode photochromic compound of Example 3 of the present invention before and after ultraviolet light irradiation and the change diagram under ultraviolet light; Figure 5 It is a line graph showing the reversibility test changes of the azobenzene dual-mode photochromic compound of the embodiment of the present invention under alternating irradiation of ultraviolet light and visible light; Figure 6 This is a graph showing changes in the information recording performance test of the azobenzene dual-mode photochromic compound according to Example 5 of the present invention. DETAILED DESCRIPTION

[0020] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0021] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from the description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0022] Embodiment 1 The first step is to synthesize the compound of structural formula (II) 326 mg 2-bromothiophene (2 mmol), 339 mg (4-aminophenyl) boronic acid (2.4 mmol), 1.382 g potassium carbonate (10 mmol), 5 mg tetrabutylammonium bromide and 116 mg tetrakis(triphenylphosphine) palladium (0.1 mmol) were added to a 100 mL double-necked round-bottom flask, 20 mL tetrahydrofuran and 4 mL deionized water were used as solvents, and the mixture was stirred and heated to reflux under nitrogen. After 8 h, the reaction was completed, and the mixture was cooled to room temperature, extracted with saturated sodium chloride solution and dichloromethane, and the organic phase was dried with anhydrous magnesium sulfate, and concentrated by rotary evaporator to obtain a crude product, which was separated by silica gel column chromatography with petroleum ether / ethyl acetate (v / v, 5 / 1) as eluent to obtain a compound of structural formula (II) as a yellow powder of 283 mg with a yield of 81%. 1 H NMR (600MHz, CDCl3) δ (ppm) 7.63 (dd, J = 6.0, 1.8 Hz, 1H), 7.59 (dd, J = 4.8,1.8 Hz, 1H), 7.50 (s, 2H), 7.17 (m, 1H), 6.56 (d, J = 7.8 Hz, 2H), 4.16 (m,2H). Figure 1 shown.

[0023] Step 2: Synthesis of the compound of formula (I) Under ice bath conditions, 350 mg of the compound of formula (II) (2 mmol) was added to a mixed solution of 25 mL of dilute hydrochloric acid (3%) and 5 mL of ice water and stirred continuously. Subsequently, 10 mL of sodium nitrate cold water solution (0.2 mol / L) was added dropwise and stirred for 20 min, then the mixture was cooled to room temperature, 212 mg of sodium carbonate (2 mmol) and 300 mg of 2-aminobenzothiazole (2 mmol) were added, and stirring was continued for 20 min. Excess sodium chloride was added to the reaction solution and filtered, the obtained precipitate was rinsed with ice water several times and dried in a vacuum drying oven, and the crude product was separated and purified by neutral alumina chromatography column using petroleum ether / ethyl acetate (v / v, 10 / 1) as eluent to obtain the compound of formula (I) as a brown solid of 465 mg with a yield of 69.0%. 1 H NMR (600 MHz, DMSO-d6) δ (ppm) 13.93 (s, 1H), 7.96 (d, J = 7.8Hz, 1H), 7.77 (d, J = 8.4 Hz, 3H), 7.52 (m, 5H), 7.35 (s, 1H), 7.16 (s, 1H). Figure 2 shown.

[0024] Embodiment 2 Photochromic performance test of compound of structural formula (I) - azobenzene dual-mode photochromic compound 1 At room temperature, the compound of formula (I) prepared in Example 1 was dispersed in acetone to prepare 10 - 5 mol / L solution. Under natural light, observe the color of the solution of compound (I) and perform a UV-visible absorption spectrum test; then after irradiating with 365nm UV light for 5min, observe the color of the solution of compound (I) and perform a UV-visible absorption spectrum test. Figure 3 The figure shows the color of the acetone solution of compound (I) under a fluorescent lamp and the UV-visible absorption spectrum before and after UV irradiation. Figure 3 It can be seen that the solution of compound (I) is light yellow, and its ultraviolet absorption spectrum has two main absorption bands, located at 275nm and 388nm respectively. After irradiation with 365nm ultraviolet light, the absorption peak of compound (I) in the long-wave region is greatly reduced, and the solution is observed to change from light yellow to colorless, indicating that compound (I) has good photochromic properties.

[0025] Embodiment 3 Photochromic performance test 2 of compound of structural formula (I) - azobenzene dual-mode photochromic compound At room temperature, the compound of formula (I) prepared in Example 1 was dispersed in acetone to prepare 10 - 5 mol / L solution. Under ultraviolet light, observe the fluorescence of the solution of compound (I) and test the fluorescence spectrum; then after irradiation with 365nm ultraviolet light for 5min, observe the fluorescence of the solution of compound (I) and test the fluorescence spectrum. Figure 4 The figure shows the fluorescence and fluorescence spectrum comparison of compound (I) acetone solution under UV light before and after UV irradiation. Figure 4 It can be seen that the solution of compound (I) originally had only very weak fluorescence. After irradiation with 365nm ultraviolet light, the fluorescence intensity at 475nm increased sharply, and the solution emitted bright cyan fluorescence, indicating that compound (I) has good photofluorescence color-changing properties.

[0026] Examples 2 and 3 show that compound (I) has dual-mode photochromic properties of color and fluorescence response.

[0027] Embodiment 4 Reversibility test of compound of structural formula (I)-azobenzene dual-mode photochromic compound At room temperature, the compound of formula (I) prepared in Example 1 was dispersed in acetone to prepare 10 - 5 mol / L solution. Test the fluorescence spectrum of the compound (I) solution, and then test the fluorescence spectrum after irradiating it with 365nm ultraviolet light for 5 minutes; after heating to 60℃, irradiate the above solution with visible light (400-750nm) for 1 hour and then test the fluorescence spectrum. Alternately irradiate with ultraviolet light and visible light, and record the changes in the fluorescence peak intensity. Figure 5 As shown, under the alternating irradiation of ultraviolet light and white light, the fluorescence intensity can be reversibly changed up to more than ten times. Although the intensity decays to a certain extent, it does not respond to the distinction between the two states, indicating that the photochromic property of compound (I) has good reversibility.

[0028] Embodiment 5 Application of compound of structural formula (I) - azobenzene dual-mode photochromic compound Under light-proof conditions, the acetone solution (1 mM) of the compound of formula (I) prepared in Example 1 was mixed with the PMMA tetrahydrofuran solution (10 wt%) at a volume ratio of 1:2, and ultrasonically dispersed for 30 min. 1 mL of the mixed solution was evenly coated on a smooth and flat quartz sheet of 3 cm × 3 cm, and dried in a vacuum drying oven at 40 ° C for 2 h to obtain a light yellow, transparent film. The digital pattern was exposed under ultraviolet light. Figure 6 As shown, the film prepared from the compound of structural formula (I) can realize preferential writing of information, and can realize repeated writing and erasing of information under the irradiation of ultraviolet light and visible light, indicating that compound (I) has good application prospects in the field of erasable information storage.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may also have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An azobenzene dual-mode photochromic compound, characterized in that: The compound has the structure shown in (I): 。 2. The method for preparing an azobenzene dual-mode photochromic compound according to claim 1, characterized in that: The specific steps of the preparation method are as follows: S1. Add the reactants 2-bromothiophene, (4-aminophenyl)boric acid, tetrakis(triphenylphosphine)palladium, anhydrous potassium carbonate and tetrabutylammonium bromide to a double-necked round-bottom flask, add a solvent, and reflux and stir under nitrogen atmosphere to obtain solution A. After purifying solution A, a compound represented by structural formula (II) is obtained. ； S2. Add the compound of structural formula (II) into the solvent, add a cold aqueous solution of sodium nitrate dropwise, and continue stirring until the temperature reaches room temperature. Then add sodium carbonate and 2-aminobenzothiazole, and continue stirring to obtain solution B. After purification of solution B, the compound represented by structural formula (I) is obtained.

3. The method for preparing an azobenzene dual-mode photochromic compound according to claim 2, characterized in that: The molar ratio of 2-bromothiophene, (4-aminophenyl)boric acid, tetrakis(triphenylphosphine)palladium, anhydrous potassium carbonate and tetrabutylammonium bromide in S1 is 1:1.2:0.05:5:0.01; the solvent is tetrahydrofuran and deionized water in a volume ratio of 5:1; the molar ratio of the reactant to the solvent is 1:100; and the reflux stirring time is 8 hours.

4. The method for preparing an azobenzene dual-mode photochromic compound according to claim 2, characterized in that: The purification in S1 is that after the stirring is completed, solution A is cooled to room temperature, the reaction liquid is extracted with a saturated sodium chloride solution and dichloromethane, the organic phase is dried with anhydrous magnesium sulfate, the solvent is removed by a reduced pressure rotary evaporator, and finally, silica gel column chromatography is performed with petroleum ether and ethyl acetate as eluents; the volume ratio of petroleum ether to ethyl acetate is 5:1, the evaporation pressure of the reduced pressure rotary evaporator is 0.08 MPa, the evaporation temperature is 40°C, and the evaporation time is 0.5 h.

5. The method for preparing an azobenzene dual-mode photochromic compound according to claim 2, characterized in that: The solvent in S2 is dilute hydrochloric acid and ice water in a volume ratio of 5:1; the concentration of the sodium nitrate solution is 0.2 mol / L, and the stirring time after addition is 20 min; the molar ratio of the compound (II), sodium nitrate, sodium carbonate and 2-aminobenzothiazole is 1:1:1:1, and the stirring time after addition is 20 min; the molar ratio of the compound of structural formula (II) to the solvent is 1:

100.

6. The method for preparing an azobenzene dual-mode photochromic compound according to claim 2, characterized in that: The purification in S2 is that after the stirring is completed, an excess amount of sodium chloride solution is added and then filtered, the obtained precipitate is rinsed with ice water for multiple times and dried in a vacuum drying oven, and finally separated by neutral alumina column chromatography using petroleum ether and ethyl acetate as eluents; the volume ratio of petroleum ether and ethyl acetate is 10:1, the evaporation pressure of the reduced pressure rotary evaporator is 0.08MPa, the evaporation temperature is 40°C, and the evaporation time is 0.5h.

7. The method for preparing an azobenzene dual-mode photochromic compound according to claim 2, characterized in that: The synthetic route of the preparation method is as follows: 。 8. The use of an azobenzene dual-mode photochromic compound according to claim 1, characterized in that: Application of the compound in information storage.

9. The use of an azobenzene dual-mode photochromic compound according to claim 8, characterized in that: The specific steps of applying the compound are as follows: S1. Mix the compound acetone solution and PMMA tetrahydrofuran solution evenly; S2. Spread the mixed solution evenly on a smooth quartz plate and store it away from light after drying.

10. The use of an azobenzene dual-mode photochromic compound according to claim 9, characterized in that: The concentration of the compound acetone solution in S1 is 1 mM, and the concentration of the PMMA tetrahydrofuran solution is 10 wt %; the volume ratio of the compound solution to the PMMA solution is 1:2; the mixing method is ultrasonic dispersion for 30 min; the mixed solution in S2 is 1 mL; the quartz plate is 3 cm×3 cm; and the drying method is drying in a vacuum drying oven at 40° C. for 2 h.

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