CN116444808A - A dynamic thermochromic luminescent material and method - Google Patents

Abstract

The invention discloses a dynamic thermochromic luminescent material and a method thereof, wherein the dynamic thermochromic luminescent material is prepared from cholesterol derivative and ZnCl dispersed in an organic solvent ₂ Is obtained by coordination interaction induction; the method comprises the following steps: dispersing cholesterol derivative in organic solvent, ultrasonic treating to obtain clear transparent solution, adding ZnCl 0.1-1.5 molar equivalent of cholesterol derivative ₂ Then ultrasonic homogenizing in an ultrasonic cleaner to obtain a series of ultrasonic cleaning agentsA dynamic thermochromic luminescent material H1 with green fluorescence; taking a dynamic thermochromic luminescent material H1, performing heat treatment, heating at a constant temperature within a range of 50-80 ℃ for about 15-25 seconds, immediately putting the obtained product into an ultrasonic cleaner filled with ice water for ultrasonic treatment, and obtaining a blue fluorescent dynamic thermochromic luminescent material H2; in summary, the present invention provides a switchable luminescent material responsive to temperature stimuli, and the materials and methods of the present invention are applicable to information encryption.

Description

A dynamic thermochromic luminescent material and method

technical field

The invention relates to the field of material technology, in particular to a dynamic thermochromic luminescent material and method.

Background technique

With the rapid development of the information age, the role of information security is becoming more and more important. How to protect information more safely is becoming a problem that cannot be ignored in the development of modern society. At the same time, the safe storage of information also involves my country's national security and national economy and people's livelihood. Photoluminescent soft materials have been widely used in sensing, display devices, and organic light-emitting diodes, and have also received high attention in security protection applications such as information storage, data recording, and encryption. However, the information directly recorded in these materials is usually visible under ambient light or ultraviolet light, and these anti-counterfeiting labels are easy to imitate, hindering their practical application in the protection of confidential information. Therefore, intelligent luminescent materials that can perceive and respond to surrounding stimuli --- stimuli-responsive luminescent materials emerged as the times require. Stimuli-responsive luminescent materials are emerging smart materials that have recently received increasing attention in sensing and imaging due to their tunable optical properties, physicochemical properties, structures, and functions in response to specific stimuli. Under external stimuli such as light, temperature, pH, redox, etc., the structure and excited state energy level of this type of luminescent switch material will change, and the material color and/or luminescence will change significantly on a macroscopic level, so its color can be used And (or) luminescent change characteristics to achieve secure storage of information. Stimuli-responsive luminescent materials that rely on the continuous addition of chemicals have long been developed for information encryption and decryption. But because these methods require invasive stimuli, consumers without specialized chemical knowledge may have difficulty processing the encoded information by adding chemicals. Therefore, there is a great need to develop alternative switchable luminescent materials with confidential cryptographic properties, capable of facile manipulation in a noninvasive manner, where the security code is initially invisible and becomes visible upon specific external stimuli. In this way, reversible information encryption and decryption can be realized. Temperature is an attractive external stimulus because it provides easy, non-invasive, high-precision control of manipulation. In addition, when many stimuli-responsive luminescent materials are applied to information encryption, the information cannot be erased or the cost is high, and the defects such as non-reusability also limit its wider application. Therefore, a simple, low-cost, automatically erasable and Recyclable new information encryption materials have very important practical significance and application prospects.

Contents of the invention

In view of the above problems, the present invention provides a dynamic thermochromic luminescent material and method, including a switchable luminescent material responsive to temperature stimuli, and the material and method of the present invention can be applied to information encryption.

For reaching this purpose, the present invention provides following technical scheme:

The first aspect of the present invention provides a dynamic thermochromic luminescent material, which is induced by coordination interaction between a cholesterol derivative dispersed in an organic solvent and ZnCl ₂ .

Preferably, the structural formula of the cholesterol derivative is formula I:

Preferably, the organic solvent includes p-xylene and ethanol. More preferably, the volume ratio of xylene and ethanol is about 8:2-2:8; even more preferably, the volume ratio of xylene and ethanol is 1:1.

Preferably, the molar concentration of the cholesterol derivative is 2-30 mM. Further preferably, the molar concentration of the cholesterol derivative is 16.37mM.

Preferably, the molar equivalent of ZnCl ₂ is 0.1-1.5 equivalent.

A second aspect of the present invention provides a method for dynamic thermochromic luminescent materials, comprising the following steps:

Cholesterol derivatives are dispersed in an organic solvent, and the mixed solution is ultrasonically obtained to obtain a clear and transparent solution, and 0.1-1.5 molar equivalents of ZnCl ₂ of the formula cholesterol derivatives are added thereto, and then ultrasonically uniform in an ultrasonic cleaner to obtain a A series of turquoise fluorescent dynamic thermochromic luminescent materials H1;

Take the dynamic thermochromic luminescent material H1, and perform the following heat treatment on it, heat it at a constant temperature in the range of 50-80°C for about 15-25s, then put it into an ultrasonic cleaner equipped with ice water for ultrasonication, and you can get the dynamic blue fluorescence Thermochromic luminescent material H2.

Preferably, the material H2 can be reversibly transformed into the material H1 after standing for 30 minutes to 1 hour.

Preferably, the structural formula of the cholesterol derivative is formula I:

Preferably, the synthetic route of the cholesterol derivative is:

Preferably, the treatment is constant temperature heating in the range of 70°C for 20s.

A third aspect of the present invention provides a method for repeated decryption and encryption, comprising the following steps:

S1. Take the material H1 sample described in any one of claims 5-8 and write encrypted information in a blank high-temperature-resistant and corrosion-resistant orifice plate;

S2. After heating the orifice plate encrypted in step S1 at a constant temperature of 50-80°C for 15-25s, immediately put it into an ultrasonic cleaner equipped with ice water for ultrasonication to decrypt the information;

S3, placing the orifice plate under the irradiation of a 365nm ultraviolet lamp to read the encrypted information;

S4. The deciphered orifice plate described in step S3 is left to stand at room temperature for 30min-1h, and then the deciphered information will be encrypted again when it is placed under a 365nm ultraviolet lamp again, that is, the blue fluorescence described in the present invention. The material H2 is reversibly restored to the cyan-emitting material H1 described in the present invention;

S5. Repeat the above steps.

Compared with the prior art, the beneficial effects and significant progress of applying the technical solution of the present invention are:

1. The present invention uses cholesterol derivatives and ZnCl ₂ to induce chiral transfer of cholesterol-zinc complexes through simple coordination interactions, and obtains a supramolecular assembly system stimuli-responsive material with thermoluminescence switching;

2. According to the two different luminescent characteristics of circularly polarized luminescent materials obtained by adding different equivalents of _ZnCl2 in the face of heat treatment operations, a dynamic and recyclable information encryption-decryption technology can be realized based on this, and the information encryption When erasing information, the technology can be erased spontaneously within a relatively short period of time, which has certain application prospects for multi-level information encryption and anti-counterfeiting.

3. The materials involved in this technology have the advantages of high sensitivity, higher safety, stability, low cost, visualization, easy operation and recyclability.

Description of drawings

In order to illustrate the technical solutions of the present invention more clearly, the accompanying drawings used in the embodiments of the present invention will be briefly introduced below.

Fig. 1 is the macrophotograph of the assembly formed by pyridine-imine functionalized cholesterol derivatives and ZnCl of Example ₂ of the present invention;

Fig. 2 is the scanning electron microscope picture of the material H1 of the embodiment 2 of the present invention;

Fig. 3 is the scanning electron micrograph of H2 of embodiment 3 of the present invention;

Fig. 4 is a circularly polarized luminescence spectrum diagram of H1 in Example 2 of the present invention;

Fig. 5 is the circularly polarized luminescence spectrum diagram of H2 in Example 3 of the present invention;

Fig. 6 is the fluorescence spectrogram of H1 and H2 of the present invention implementation 2 and 3;

Fig. 7 is an application example of the material H1 of Example 4 of the present invention as the only starting material in information encryption-decryption and self-erasing.

Detailed ways

Example 1 Preparation of Cholesterol Derivative Ligand Molecular Formula I

The synthetic route of formula I is as follows:

Concrete synthetic steps of formula I:

1.1. Referring to Zhang, Q. et al. Recyclable palladium (II) imino-pyridine complex immobilized on mesoporous silica as a highly active and recoverable catalyst for Suzuki–Miyaura coupling reactions in aqueous medium, Tetrahedron 2013, 69 (2), 447-454 Method for preparing 4-[(2-pyridylmethylene)amino]phenol;

1.2, 4-[(2-pyridylmethylene)amino]phenol (1g, 5.04mmol) was dissolved in 20ml of dry dichloromethane and triethylamine (0.6ml) mixed solvent, and the mixed solution was added drop by drop Pour into 80ml of dichloromethane solution containing triethylamine (0.72mL, 5.2mmol) and cholesterol formyl chloride (3.0g, 6.7mmol), and stir at 0°C for about 10 minutes;

1.3. After transferring to room temperature and continuing to stir for 3 hours, the solvent was removed by rotary evaporation, and the crude product was purified by flash silica gel column chromatography (ethyl acetate/dichloromethane, V/V, 1/10) to obtain formula I, yield 85%.

The structural characterization data of formula I are as follows:

¹ H NMR (300MHz, CDCl3) δ8.74(d, J=4.3Hz, 1H), 8.62(s, 1H), 8.22(d, J=7.9Hz, 1H), 7.84(td, J=7.8, 1.6 Hz,1H),7.40(ddd,J=7.4,4.8,1.1Hz,1H),7.36-7.30(m,2H),7.28-7.23(m,2H),5.45(d,J=4.8Hz,1H) ,4.71-4.52(m,1H),2.59-2.42(m,2H),2.12-1.69(m,6H),1.63-1.48(m,7H),1.40-1.09(m,10H),1.09-0.99( m,6H),0.94(d,J=6.5Hz,3H),0.89(dd,J=6.6,1.1Hz,6H),0.71(s,3H).

13C NMR (150MHz, CDCl3) δ160.95, 154.62, 153.17, 150.03, 149.95, 148.75, 139.31, 136.89, 125.42, 123.42, 122.29, 122.16, 122.04, 79.17, 56.87, 56 .31, 50.16, 42.50, 39.89, 39.70, 38.13, 37.02 ,36.74,36.37,35.98,32.10,32.02,28.42,28.21,27.83,24.47,24.02,23.03,22.77,21.24,19.48,18.91,12.06.

HRMS(MALDI-TOF):m/z calcd.for C40H54N2O3[M] ⁺ :611.4213,found:611.1422.

Example 2 Supramolecular material H1 formed by the assembly of cholesterol derivative ligand Ⅰ and ZnCl ₂

Take a clean sample vial, weigh 3 mg of small organic molecules represented by formula I (16.37 mmol), and pipette 150 μL of p-xylene and ethanol solvents into the vial to dissolve them completely. Prepare a high-concentration mother solution of ZnCl2 in methanol, and dissolve ZnCl2 completely in methanol by ultrasonication. By calculating the amount of ZnCl2 mother liquor required to add different molar equivalents of ZnCl2 of formula I, pipette the corresponding volume of ZnCl2 mother liquor to a sample bottle containing 3 mg of small organic molecules shown in formula I to prepare 0.1-1.5 equivalents of ZnCl2 mother liquor The assembly corresponding to the cholesterol zinc complex is the dynamic thermochromic luminescent material H1.

H1 exhibits turquoise fluorescence emission, and its macroscopic photos, scanning electron microscope images, circularly polarized luminescence spectra, and fluorescent light spectra are shown in Figures 1, 2, 4, and 6. It is observed from Figure 1 that H1 is white and viscous macroscopically, and its microscopic appearance is shown in Figure 2 as a helical band with a left-handed helical direction. H1 shows turquoise emission, and its emission fluorescence spectrum is shown in Figure 6. The precise emission position is located near 478nm. The circularly polarized luminescence spectrum shown in Figure 4 shows the excited-state supramolecular chirality of material H1, and the emission position is similar to the results of the fluorescence spectrometer.

Example 3 Dynamic thermochromic luminescent material H2 formed by assembly of dynamic thermochromic luminescent material H1

Take the dynamic thermochromic luminescent material H1 prepared in Example 2, and perform the following heat treatment process: heat the sample bottle at 70°C for 15-20 seconds, then immediately put it into an ultrasonic cleaner equipped with ice water, and ultrasonicate the sample bottle for about 30 seconds , the blue fluorescent dynamic thermochromic luminescent material H2 can be obtained, and the material H2 can reversibly return to H1 after standing for 1 hour. The power of the ultrasonic cleaner is 150W.

The scanning electron microscope images, circularly polarized luminescence spectra, and fluorescence spectra of material H2 are shown in Figures 3, 5, and 6. From Figure 1, it can be seen that H2 is light yellow and viscous macroscopically, and its microscopic appearance is mainly microsphere shape as shown in Figure 3. H2 shows blue emission, and its emission fluorescence spectrum is shown in Figure 6, which accurately emits The position is located near 458nm, and the circularly polarized luminescence spectrum shown in Figure 5 shows the excited state supramolecular chirality of material H2, and the emission position is similar to the results of the fluorescence spectrometer.

Example 4 Supramolecular Materials in Information Encryption Experiments

In conjunction with accompanying drawing 7, the actual operation process of the supramolecular material formed by the assembly of the cholesterol derivative ligand and ZnCl2 in the information encryption is illustrated, and the specific steps are as follows:

4.1. The dynamic thermochromic luminescent material H1 obtained by adding ZnCl2 lower than 0.5 molar equivalent and the dynamic thermochromic luminescent material H1 obtained by adding ZnCl2 higher than 0.7 molar equivalent are used as two inks respectively. In this example, the two inks Take material H1 with 0.3 molar equivalent and 0.8 molar equivalent as an example.

4.2. Prepare a blank high-temperature-resistant and corrosion-resistant orifice plate with a sealed cover. The information array is 5×8. Use a pipette gun to extract a 0.8 molar equivalent material H1 sample and write encrypted information in the blank high-temperature-resistant and corrosion-resistant orifice plate: 963 For information encryption, 20 μL of sample was evenly added to each well, and the blank wells in the array except for the encrypted information were filled with 0.3 molar equivalent of material H1, and the added amount remained consistent, and then the orifice plate was sealed.

4.3. Heat the sealed orifice plate at a constant temperature of 70°C for 15-20s, then immediately put it into an ultrasonic cleaner equipped with ice water for about 20s to decrypt the information, and read the information by placing the orifice plate under the irradiation of a 365nm ultraviolet lamp. Get the encrypted information, and you can see the information that emits blue light: as shown in Figure 7, 963 is the encrypted information read;

4.4 Let the orifice plate after the decryption process described in step 3 stand at room temperature for about 1 hour, and then put it under a 365nm ultraviolet lamp again, and the decrypted information will be encrypted again, that is, the blue fluorescent material H2 can be reversibly restored to the emission level. The material H1 of cyan light, as shown in FIG. 7 , cannot see the encrypted information 963 under the 365nm ultraviolet lamp at this time, and the heat treatment process described in step 3 can be performed again to perform the repeated decryption-encryption process.

The applicant declares that, during the description of the above specification:

The descriptions of the terms "this embodiment", "the embodiment of the present invention", "as shown", "further", "further improved technical sub-solutions" mean the specific features described in this embodiment or example , structures, materials or characteristics are included in at least one embodiment or example of the present invention; in this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example, and the described specific features, structures, Materials or features can be combined or combined in any one or more embodiments or examples in an appropriate manner; in addition, on the premise of no conflict, those skilled in the art can combine different embodiments described in this specification or examples and features of different embodiments or examples are combined or combined.

Finally, it should be stated that:

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them;

Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features. , and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, non-essential improvements, adjustments or replacements made by those skilled in the art according to the contents of this specification belong to the scope of the present invention scope of protection claimed.

Claims (10)

1. A dynamic thermochromic luminescent material is characterized by comprising cholesterol derivative and ZnCl dispersed in an organic solvent ₂ Is induced by coordination interaction.

2. The dynamic thermochromic luminescent material according to claim 1, wherein the cholesterol derivative has a structural formula of formula i:

3. a dynamic thermochromic luminescent material according to claim 1, wherein the organic solvent comprises p-xylene and ethanol.

4. A dynamic thermochromic luminescent material according to claim 1, wherein the molar concentration of the cholesterol derivative is 2 to 30mM.

5. A dynamic thermochromic luminescent material as recited in claim 1, wherein ZnCl is a mixture of both ₂ The molar equivalent of (2) is 0.1 to 1.5.

6. A method of dynamically thermochromic luminescent material, comprising:

dispersing cholesterol derivative in organic solvent, ultrasonic treating to obtain clear transparent solution, adding ZnCl 0.1-1.5 molar equivalent of cholesterol derivative ₂ Then ultrasonic uniform is carried out in an ultrasonic cleaner, and a series of blue-green fluorescent dynamic thermochromic luminescent materials H1 are obtained;

the dynamic thermochromic luminescent material H1 is taken, subjected to heat treatment, heated at constant temperature within the range of 50-80 ℃ for about 15-25 seconds, immediately placed into an ultrasonic cleaner filled with ice water for ultrasonic treatment, and then the blue fluorescent dynamic thermochromic luminescent material H2 is obtained.

7. The method of claim 6, wherein the material H2 is reversible to material H1 after standing for 30 min-1H.

8. The method of claim 6, wherein the cholesterol derivative has the structural formula i:

9. the method of claim 8, wherein the cholesterol derivative is synthesized according to the following steps:

10. a method capable of repeatedly decrypting and encrypting, which is characterized by comprising the following steps:

s1, taking the material H1 sample according to any one of claims 5-8, and writing encryption information in a blank high-temperature-resistant corrosion-resistant pore plate;

s2, placing the pore plate encrypted in the step S1 into an ultrasonic cleaner filled with ice water for ultrasonic treatment after heating at the constant temperature of 50-80 ℃ for 15-25S, and decrypting information;

s3, the pore plate is placed under the irradiation of an ultraviolet lamp with the wavelength of 365nm to read the encrypted information;

s4, standing the decrypted pore plate in the step S3 at room temperature for 30min-1H, and then encrypting the decrypted information again when the pore plate is placed under an ultraviolet lamp of 365nm again, namely, the blue-emitting material H2 in any one of claims 6-9 is reversibly recovered to the green-emitting material H1 in any one of claims 6-9;

s5, repeating the steps.