A tetraphenyl ethylene salicyl aldehyde aniline schiff base derivative, preparation and application thereof

Abstract

This invention discloses a tetraphenylphenyl salicylate-based aniline Schiff base derivative, its preparation, and its applications. This derivative is prepared from 2-hydroxy-5-(1,2,2-triphenylphenyl)-benzaldehyde and aniline and its derivatives, and can be used as a photochromic material in the fields of data encryption and anti-counterfeiting. The preparation process of the tetraphenylphenyl salicylate-based aniline Schiff base derivative of this invention is simple, and its structure is novel. Utilizing its photoluminescent properties, it can be used in anti-counterfeiting and other fields, exhibiting characteristics such as a large color-changing range, short fading time, and stable properties.

Description

Technical Field

[0001] This invention relates to a Schiff base and its preparation and application, particularly a tetraphenylsalicylic acid aldehyde aniline Schiff base derivative and its preparation and application. Background Technology

[0002] Ensuring the security and authenticity of information has become a major concern for the public, placing higher demands on encryption methods and anti-counterfeiting materials. Therefore, research into encryption and anti-counterfeiting materials is particularly important.

[0003] Currently, some photochromic, phosphorescent, and fluorescent materials have been applied in the field of anti-counterfeiting. Among them, the design and development of photochromic compounds have attracted much attention in the field of anti-counterfeiting and encryption materials. In recent years, some important photochromic compounds, such as spiropyran, azobenzene, and aromatic free radicals, which possess optical isomers, have been reported and have been widely used in information encryption and anti-counterfeiting. However, most photochromic materials often have limited molecular motion and rotation in the aggregated state, resulting in the inability to form optical isomers. Therefore, most of them only possess photochromic properties in the dissolved state. Furthermore, the color change amplitude of aggregated photochromic materials is controlled by the crystallization process, making the preparation of materials very cumbersome and time-consuming. In addition, since crystalline and amorphous materials have different color-changing properties, it is difficult to accurately explain their color-changing mechanisms, which greatly limits the exploration of the mechanism of photochromic materials and their development and application in the fields of information encryption and anti-counterfeiting. Organic crystals have a well-defined structure and molecular arrangement, providing an ideal model system for studying the influence of intermolecular forces and molecular arrangement on the solid-state luminescence properties of materials. Therefore, exploring amorphous and photochromic materials with excellent color-changing properties in crystalline and amorphous states, which have the advantages of simple, rapid, and stable preparation, is a very meaningful research endeavor.

[0004] Salicylic aldehyde-aniline Schiff bases are a class of molecules possessing solid-state photochromic properties. Due to their simple synthesis and ease of modification, they are widely used in the construction of photochromic materials and in the fields of encryption / decryption and anti-counterfeiting materials. The main mechanism of photochromism of salicylic aldehyde-aniline Schiff bases is described in the appendix to the specification. Figure 1 As shown, this is a dual process of molecule from "enol form → cis ketone form → trans ketone form" (ESIPT-ISO). In this process, the enol form can be photoactivated to the cis ketone form based on the intramolecular proton transfer (ESIPT) in the excited state, causing a red shift in the absorption spectrum. Then, the ISO process transforms the molecule into the trans ketone form, further enhancing the absorption spectrum.

[0005] Because salicylaldehyde-aniline Schiff bases tend to form a six-membered closed ring structure through intramolecular hydrogen bonding during crystallization, which is favorable for the ESIPT process, early studies focused on modulating the ISO process to study photochromism, considering the ISO process to be the main factor influencing photochromism. To further facilitate the ISO process, researchers introduced groups with large steric effects into the salicylaldehyde-aniline Schiff base, disrupting π-π stacking and inducing active molecular motion (the ISO process), thereby producing photochromism. However, with further research, researchers discovered that the ISO process is not the absolute factor influencing photochromism; the ESIPT process is particularly important and can also become a major factor affecting the ESIPT-ISO dual process.

[0006] For example, Tang and Cai et al. introduced alicyclic compounds into salicylaldehyde-aniline Schiff bases in 2021, proposing that the ESIPT-ISO synergistic effect is beneficial to photochromism. Subsequently, in 2023, they introduced a propeller-like triphenylamine group into salicylaldehyde-aniline Schiff bases, finding that crystallization and rapid precipitation methods can affect the formation of intramolecular hydrogen bonds, thereby modulating the ESIPT effect, and proposing that the ESIPT process is the main factor affecting the ESIPT-ISO dual process. This literature also suggests that different aggregation states affect the ESIPT process. With the development of aggregate science, it has been found that some compounds exhibit properties superior to those of unimolecular aggregates, and some compounds exhibit a 1+1>2 effect; AIE is the most typical example. Although the importance of holistic thinking has been recognized in aggregate research, how to effectively explore the complex interactions in aggregates, construct clear structure-activity relationships, especially in understanding the new structures and properties that emerge after aggregation, remains unclear.

[0007] Based on this, this application uses an aldehyde-amine exchange strategy to react 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde with aniline of different substituents to obtain different tetrastyrene salicylaldehyde-aniline Schiff base derivatives. The structure of the derivatives is adjusted based on the ESIPT-ISO process, so that the derivatives have many advantages such as large color change range, short fading time and stable properties.

[0008] The purpose of this invention is to provide a tetraphenylphenylsalicylic aldehyde-aniline Schiff base derivative, its preparation, and its applications. The tetraphenylphenylsalicylic aldehyde-aniline Schiff base derivative of this invention has a simple preparation process and a novel structure. Its photoluminescent properties can be utilized in fields such as anti-counterfeiting, exhibiting characteristics of large color change range, short fading time, and stable properties.

[0009] A tetraphenylsalicylic acid aniline Schiff base derivative has the following chemical structural formula: ; R1 represents benzene and its derivatives.

[0010] Preferably, in the aforementioned tetraphenylphenyl salicylate aniline Schiff base derivative, R1 has one of the following structures: , , , or .

[0011] A method for preparing the aforementioned tetraphenylsalicylic aldehyde aniline Schiff base derivative is prepared using 2-hydroxy-5-(1,2,2-triphenyl)-benzaldehyde and aniline and its derivatives as raw materials.

[0012] Preferably, the preparation method of the aforementioned tetraphenylphenyl salicylate aniline Schiff base derivative includes the following steps: 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and aniline or its derivatives were dissolved in an ethanol solution, concentrated sulfuric acid was added dropwise, the mixed solution was reacted, filtered, washed, and dried to obtain a slightly yellow solid powder, which is the tetrastyrene salicylaldehyde aniline Schiff base derivative.

[0013] Preferably, in the aforementioned method for preparing the tetraphenylphenyl salicylaldehyde aniline Schiff base derivative, the molar ratio of 2-hydroxy-5-(1,2,2-triphenylphenyl)-benzaldehyde to aniline or its derivative is 1:1-1.5.

[0014] Preferably, in the aforementioned method for preparing the tetraphenylsalicylic aldehyde aniline Schiff base derivative, the volume molar ratio of concentrated sulfuric acid to the total mass of 2-hydroxy-5-(1,2,2-triphenyl)-benzaldehyde and aniline or its derivative is 1 mL: 20-30 g.

[0015] Preferably, in the aforementioned method for preparing the tetraphenylphenyl salicylaldehyde aniline Schiff base derivative, the reaction is carried out by stirring at room temperature for 20-30 hours.

[0016] Preferably, in the aforementioned method for preparing the tetraphenylsalicylic acid aldehyde aniline Schiff base derivative, the washing is performed by washing with ethanol 3-7 times.

[0017] Preferably, in the aforementioned method for preparing the tetraphenylphenyl salicylaldehyde aniline Schiff base derivative, the drying process is vacuum drying.

[0018] An application of the aforementioned tetraphenylsalicylic aldehyde aniline Schiff base derivative as a photochromic material in the field of data encryption and anti-counterfeiting.

[0019] 1. The preparation process of the tetraphenylphenyl salicylaldehyde aniline Schiff base derivative of the present invention is simple and conducive to industrial implementation.

[0020] 2. The tetraphenylphenyl salicylaldehyde aniline Schiff base derivative of the present invention has a novel structure and belongs to a new type of compound.

[0021] 3. The tetraphenylsalicylic acid aldehyde aniline Schiff base derivative of the present invention has photochromic properties and can be used in anti-counterfeiting and other fields.

[0022] 5. The tetraphenylsalicylic acid aldehyde aniline Schiff base derivative of the present invention has the characteristics of large color change range, short fading time and stable properties. Attached Figure Description

[0023] Appendix Figure 1 A schematic diagram of the photochromic mechanism of salicylaldehyde-aniline Schiff base.

[0024] Appendix Figure 2 The crystal structure diagrams are of the derivatives obtained in Examples 1-5 of this invention.

[0025] Appendix Figure 3 The crystal structure diagrams are of the derivatives obtained in Comparative Examples 1-3 of this invention.

[0026] Appendix Figure 4 The theoretical UV-Vis absorption spectra of the derivatives obtained in Examples 1-5 and Comparative Examples 1-3 of this invention are shown. (A) TPE-P, (B) TPE- p -tBuP、(C)TPE- o -FP、(D)TPE- p -FP、(E)TPE- p -MP、(F)TPE- o -MOP、(G)TPE- o -BrP and (H)TPE- p -NO2P.

[0027] Appendix Figure 5 The energy distribution and corresponding optimized structure of the isomerization reaction from ketone to trans-ketone obtained in Examples 1-5 and Comparative Examples 1-3 of this invention are shown.

[0028] from Figure 4 and Figure 5 The comparison shows that aniline derivatives with different structures and substituents have the same effect on the optical properties of the compounds, which is of great significance for their subsequent application as photochromic materials in the fields of data encryption and anti-counterfeiting.

[0029] Appendix Figure 6Applications of color-changing information encryption and storage for the derivatives of this invention: (a) Schematic diagram of the preparation of color-changing ink and its color-changing anti-counterfeiting effect; (b) Color-changing anti-counterfeiting effect of compound crystals and color-changing ink on various carriers; (c) Time-encrypted storage and decryption of data; (d) Encryption and encryption application of QR code information. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0031] Embodiments of the present invention Example 1

[0032] Synthesis of compound TPE-P: 2-Hydroxy-5-(1,2,2-tristyrene)-benzaldehyde (0.38 g, 1 mmol) and aniline (0.12 g, 1.2 mmol) were dissolved in 20 mL of ethanol solution, and 20 μL of concentrated sulfuric acid was added dropwise. The mixture was stirred at room temperature for 24 h, filtered, and the solid was washed five times with ethanol and dried under vacuum to obtain 3.16 g of a pale yellow solid powder, with a yield of 70%.

[0033] TPE-P: mp171℃; 1 HNMR (600MHz, DMSO-) d 6 )δ13.10(s,1H),8.75(s,1H),7.42(t, J =7.8Hz,2H),7.35(d, J =7.4Hz,2H),7.28(dd, J =13.2,4.8Hz,2H),7.19–7.07(m,10H),7.03–6.95(m,6H),6.72(d, J =8.5Hz, 1H)ppm. 13 CNMR (151MHz, DMSO-) d 6 )δ163.09,159.09,147.89,143.30,143.04,140.36,139.66,135.89,134.45,134.22,130.81,130.74,130.70,129 .46,128.92,128.00,127.94,127.88,127.01,126.71,126.57,126.52,121.39,118.84,116.20ppm.ESI-TOF:[M+H] + calcdforC 33 H 26 NO+ :452.1936,found452.2040. Example 2

[0034] Synthesis of compound TPE-o-FP: 0.38 g of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and Dissolve 0.12 g in 20 mL of ethanol solution, add 20 μL of concentrated sulfuric acid dropwise, stir the mixture at room temperature for 24 h, filter, wash the solid 5 times with ethanol, and dry under vacuum to obtain a slightly yellow solid powder.

[0035] TPE- o -FP:mp162℃; 1 HNMR (600MHz, DMSO-) d 6 )δ13.23(s,0.5H),12.93(s,0.5H),8.74(s,1H),7.42(dd,J=8.9,5.0Hz,1H),7.24(ddd,J=16.3,12.6 ,8.4Hz,4H),7.19–7.07(m,9H),6.99(ddd,J=19.4,13.5,6.9Hz,7H),6.71(dd,J=8.5,6.0Hz,1H)ppm. 13 CNMR (151MHz, DMSO-) d 6 )δ163.01,162.16,160.20,159.09,158.94,145.18,144.41,143.29,143.05,140.37,14 0.31,139.69,139.64,136.60,135.89,135.68,134.38,134.26,134.17,130.80,130.74 ,130.70,129.95,127.99,127.93,127.87,126.70,126.57,126.52,123.32,123.26,121 .25,118.84,116.22,116.18,116.15,116.07,115.65,115.51,20.64ppm.ESI-TOF:[M+H] + calcdforC 33 H 25 FNO + :470.1842,found470.1900. Example 3

[0036] compound TPE-p -FP synthesis: 0.38 g of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and Dissolve 0.12 g in 20 mL of ethanol solution, add 20 μL of concentrated sulfuric acid dropwise, stir the mixture at room temperature for 24 h, filter, wash the solid 5 times with ethanol, and dry under vacuum to obtain a slightly yellow solid powder.

[0037] TPE- p -FP:mp175℃; 1 HNMR (600MHz, DMSO-) d 6 )δ13.02(s,1H),8.85(s,1H),7.51(t,J=8.0Hz,1H),7.34–7.27(m,3H),7.26–7.21(m,1H),7.1 9–7.07(m,9H),7.02(dd,J=13.2,6.5Hz,5H),6.97(d,J=6.8Hz,2H),6.73(d,J=8.5Hz,1H)ppm. 13 CNMR (151MHz, DMSO-) d 6 )δ164.44,159.19,156.25,154.61,143.27,143.01,140.44,139.56,13 6.36,135.73,135.67,134.46,134.34,130.81,130.74,130.69,128.46 ,128.40,128.02,127.95,127.87,126.73,126.60,126.54,125.19,125 .16,120.71,118.87,116.39,116.32,116.26,39.60ppm.ESI-TOF:[M+H] + calcdforC 33 H 25 FNO + :470.1842,found470.1932. Example 4

[0038] Synthesis of compound TPE-p-MP: 0.38 g of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and Dissolve 0.12 g in 20 mL of ethanol solution, add 20 μL of concentrated sulfuric acid dropwise, stir the mixture at room temperature for 24 h, filter, wash the solid 5 times with ethanol, and dry under vacuum to obtain a slightly yellow solid powder.

[0039] TPE- p -MP:mp167℃; 1 HNMR (600MHz, DMSO-) d 6 )δ13.33(s,1H),8.72(s,1H),7.36(d,J=8.9Hz,2H),7.21(d,J=2.2Hz,1H),7.13(ddd,J=21.3,15 .4,7.1Hz,9H),7.01(t,J=7.3Hz,4H),6.99–6.94(m,5H),6.69(d,J=8.5Hz,1H),3.77(s,3H)ppm. 13 CNMR (151MHz, DMSO-) d 6 )δ160.82,158.98,158.58,143.33,143.08,140.53,140.27,139.73,135.37,134.25,134.12,130.80,130.74 ,130.70,127.98,127.92,127.86,126.68,126.54,122.66,118.92,116.09,114.66,55.42ppm.ESI-TOF: [M+H] + calcdforC 34 H 28 NO + :466.2093,found466.2189. Example 5

[0040] Synthesis of compound TPE-p-tBuP: 0.38 g of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and Dissolve 0.12 g in 20 mL of ethanol solution, add 20 μL of concentrated sulfuric acid dropwise, stir the mixture at room temperature for 24 h, filter, wash the solid 5 times with ethanol, and dry under vacuum to obtain a slightly yellow solid powder.

[0041] TPE- p -tBuP:mp215℃; 1 HNMR (600MHz, DMSO-) d 6)δ13.26(s,1H),8.74(s,1H),7.43(d,J=8.5Hz,2H),7.29(d,J=8.5Hz,2H),7.24(d,J=2.0Hz,1H) ,7.13(ddq,J=29.3,14.5,7.3Hz,10H),7.04–6.93(m,6H),6.71(d,J=8.5Hz,1H),1.28(s,9H)ppm. 13 CNMR (151MHz, DMSO-) d 6 )δ162.39,159.12,149.74,145.16,143.31,143.04,140.33,139.68,135.71,134.39,134.15,130.81,130.73,130.69 ,128.00,127.94,127.88,126.71,126.56,126.52,126.20,121.02,118.85,116.17,34.36,31.16ppm.ESI-TOF: [M+H] + calcdforC 37 H 34 NO + :508.2652,found508.2659. Comparative Example 1: Synthesis of compound TPE-p-MOP: 0.38 g of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and Dissolve 0.12 g in 20 mL of ethanol solution, add 20 μL of concentrated sulfuric acid dropwise, stir the mixture at room temperature for 24 h, filter, wash the solid 5 times with ethanol, and dry under vacuum to obtain a slightly yellow solid powder.

[0042] TPE- p -MOP: mp 120℃; 1 H NMR (600 MHz, DMSO- d 6 ) δ 13.24 (s, 1H), 8.74(s, 1H), 7.24 (dt, J = 14.2, 8.3 Hz, 5H), 7.19 – 7.07 (m, 9H), 7.04 – 6.94(m, 7H), 6.70 (d, J = 8.5 Hz, 1H), 2.31 (s, 9H) ppm. 13 C NMR (151 MHz, DMSO- d6 ) δ 162.16, 159.09, 145.19, 143.31, 143.05, 140.31, 139.69, 136.59, 135.67,134.38, 134.17, 130.80, 130.74, 130.70, 129.94, 127.98, 127.93, 127.87,126.69, 126.55, 121.25, 118.84, 116.15, 20.64 ppm. ESI-TOF: [M+H] + calcd forC 34 H 28 NO2 + : 482.2042, found 482.2141. Comparative Example 2: Synthesis of compound TPE-o-BrP: 0.38 g of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and Dissolve 0.12 g in 20 mL of ethanol solution, add 20 μL of concentrated sulfuric acid dropwise, stir the mixture at room temperature for 24 h, filter, wash the solid 5 times with ethanol, and dry under vacuum to obtain a slightly yellow solid powder.

[0043] TPE- o -BrP: mp 216℃; 1 H NMR (600 MHz, DMSO- d 6 ) δ 13.05 (s, 1H), 8.79(s, 1H), 7.73 (d, J = 7.9 Hz, 1H), 7.52 (d, J = 8.0 Hz, 1H), 7.44 (t, J = 7.2Hz, 1H), 7.29 (d, J = 2.1 Hz, 1H), 7.20 – 7.09 (m, 10H), 7.06 – 7.00 (m, 5H), 6.97 (d, J = 7.0 Hz, 2H), 6.74 (d, J = 8.5 Hz, 1H) ppm. 13 C NMR (151 MHz, DMSO- d 6) δ 164.30, 159.17, 145.84, 143.28, 143.24, 143.00, 140.46, 139.52,136.48, 134.92, 134.37, 132.94, 130.81, 130.74, 130.69, 129.03, 128.59,128.04, 127.96, 127.88, 126.73, 126.62, 126.54, 120.03, 119.43, 118.66,116.33 ppm. ESI-TOF: [M+H] + calcd for C 33 H 25 BrNO + : 530.1041, found 530.1141. Comparative Example 3: Synthesis of compound TPE-p-NO2P: 2-Hydroxy-5-(1,2,2-tristyrene)-benzaldehyde (0.38 g) and p-nitroaniline (0.12 g) were dissolved in 20 mL of ethanol solution, and 20 μL of concentrated sulfuric acid was added dropwise. The mixture was stirred at room temperature for 24 h, filtered, and the solid was washed 5 times with ethanol and dried under vacuum to obtain a slightly yellow solid powder.

[0044] TPE- p -NO2P: mp 241℃; 1 H NMR (600 MHz, DMSO- d 6 ) δ 12.26 (s, 1H), 8.82 (s, 1H), 8.26 (d, J = 9.0 Hz, 2H), 7.53 (d, J = 9.0 Hz, 2H), 7.35 (d, J= 2.3 Hz, 1H), 7.13 (tdt, J = 21.3, 14.3, 7.3 Hz, 10H), 7.05 (dd, J = 8.6,2.3 Hz, 1H), 7.02 (dd, J = 9.6, 4.3 Hz, 4H), 6.99 – 6.93 (m, 2H), 6.74 (d, J= 8.6 Hz, 1H) ppm. 13 C NMR (151 MHz, DMSO- d 6) δ 165.11, 159.04, 154.55,145.44, 143.24, 142.97, 140.52, 139.50, 136.92, 134.53, 134.12, 130.79,130.74, 130.68, 128.03, 127.97, 127.88, 126.74, 126.62, 126.55, 125.04,122.51, 119.06, 116.36 ppm. ESI-TOF: [M+H] + calcd for C 33 H 25 N2O3 + : 497.1787, found 497.1868. Experimental Example Considering the excellent photochromic properties of these compounds, we explored their applications in data encryption and anti-counterfeiting. First, we prepared a photochromic ink by mixing and grinding the compounds with wormwood and castor oil, such as... Figure 6 As shown in Figure a, after printing the Guizhou Medical University emblem and Professor Zhang Qilong's personal QR code onto paper using color-changing ink, the printed pattern is clearly visible when exposed to ultraviolet light, and the QR code can be scanned with a mobile phone to obtain relevant information. Furthermore, excellent photochromic information encryption and decryption effects can be achieved on fabrics and even inorganic carriers like gypsum board. Figure 6 (b) Furthermore, it has been preserved for three years (printed in 2022 to the present), and the effect remains excellent. We washed the fabric printed with the photochromic material five times in a washing machine with laundry detergent (Tide), and the photochromic material still exhibited good color-changing effects. This demonstrates the applicability of our developed material. Subsequently, we combined and printed the sequence "8888-4960-1357" using color-changing inks prepared from TPE-P, TPE-o-FPh, and TPE-p-tBuP, which have significantly different fading times, according to a certain pattern. For example... Figure 6 As shown in Figure c, after ultraviolet light irradiation, all three molecules are excited, displaying "8888"; subsequently, TPE-P, with the shortest fading time, fades first, displaying "4960"; finally, TPE-o-FP fades, leaving only TPE-p-tBuP, ultimately displaying "1357". By utilizing the difference in fading time, we have achieved encryption and storage of this "one-dimensional" data. How effective is the encryption for more complex and higher-dimensional data storage formats, such as QR codes? We printed QR codes using two printing modes with TPE-P (shortest fading time) and TPE-p-tBuP (longest fading time): half-printing and cross-overprinting. The results are as follows... Figure 6As shown in diagram d, in half-printing, since the two inks each occupy half of the QR code, there is no interference between them, so the QR code displayed after illumination can be scanned normally. When TPE-P fades, since only the half of the QR code occupied by TPE-p and tBuP remains, it cannot be scanned. Cross-over printing, on the other hand, involves printing the two inks alternately and overlapping, causing mutual interference. Therefore, the QR code displayed after illumination cannot be scanned. Only after 5 seconds, when TPE-P fades and its interference is eliminated, can the QR code displaying only TPE-p and tBuP be scanned normally to obtain information.

[0045] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A tetraphenylphenyl salicylic aldehyde aniline Schiff base derivative, characterized in that, Its chemical structural formula is shown below: ； R1 represents benzene and its derivatives.

2. The tetraphenylphenyl salicylic aldehyde aniline Schiff base derivative according to claim 1, characterized in that, R1 can be one of the following structures: , , , or .

3. A method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 1 or 2, characterized in that: It is prepared from 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and aniline and its derivatives.

4. The method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 3, characterized in that, The preparation method includes the following steps: 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and aniline or its derivatives were dissolved in an ethanol solution, concentrated sulfuric acid was added dropwise, the mixed solution was reacted, filtered, washed, and dried to obtain a slightly yellow solid powder, which is the tetrastyrene salicylaldehyde aniline Schiff base derivative.

5. The method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 4, characterized in that: The molar ratio of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde to aniline or its derivatives is 1:1-1.

5.

6. The method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 4, characterized in that: The volume molar ratio of the concentrated sulfuric acid to the total mass of 2-hydroxy-5-(1,2,2-tristyrene)-benzaldehyde and aniline or its derivatives is 1 mL: 20-30 g.

7. The method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 4, characterized in that: The reaction was carried out by stirring at room temperature for 20-30 hours.

8. The method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 4, characterized in that: The washing process involves washing with ethanol 3-7 times.

9. The method for preparing the tetraphenylphenyl salicylate aldehyde aniline Schiff base derivative according to claim 4, characterized in that: The drying process described is vacuum drying.

10. The application of a tetraphenylsalicylic acid aldehyde-aniline Schiff base derivative according to claim 1 or 2 as a photochromic material in the field of data encryption and anti-counterfeiting.

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