Dual-band photoresponse supramolecular material based on pillararene and application of supramolecular material in information encryption and anti-counterfeiting

Abstract

The invention provides a pillararene-based dual-band photoresponse supramolecular material and application thereof, through self-assembly of a pillararene derivative subject and a photoinert fluorescent object, ultraviolet light is utilized to excite the polarity change of a subject cavity to drive the subject-object to act, and dual-band reversible regulation and control of fluorescence quenching and recovery are realized. The material is encrypted under 254nm ultraviolet light and decrypted under visible light, the cycle life is more than or equal to 10 times, and the material has excellent hydrophobic stability. The material is suitable for high-order information encryption and anti-counterfeit labels, and the technical defects that a traditional photoresponse material depends on a photoactive object, the cycle life is short, and a signal source is single are overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of supramolecular functional materials and optical encryption, and relates to a dual-band light-responsive supramolecular material based on pillararenes and its application in information encryption and anti-counterfeiting. Background Art

[0002] In the field of supramolecular photoresponsive materials, host-guest interactions based on macrocycles are a classic approach for constructing supramolecular building blocks. Typically, a host-guest supramolecule spontaneously forms between a macrocyclic host and a guest of matching size or structure. However, under conditions such as light or acid-base reactions, the guest molecule undergoes cis-trans isomerization or acid-base changes, weakening the host-guest interaction with the macrocycle and leading to disassembly of the host-guest supramolecule. For example, host-guest interaction systems involving guest molecules such as azobenzene, anthracene, fumaramide, diarylethenes, spiropyran, stilbene, and coumarin with macrocycles such as cyclodextrin and cucurbituril all disassemble under light due to changes in the guest molecule's structure. For a long time, research on supramolecular photoresponsive intelligent systems has primarily relied on guest molecules exhibiting significant structural changes, such as photoisomerization. However, these guest molecules often possess large conjugated structures, which are easily destroyed after repeated photoswitching, resulting in short cycle life and unsuitable for sustainable development. Pillararene macrocycles, on the other hand, lack readily oxidizable groups, such as conjugated double bonds, and therefore exhibit high optical stability.

[0003] In summary, the existing technologies have the following defects: traditional photoresponsive materials (such as azobenzene / cyclodextrin systems) rely on the isomerization of photoactive guests and have a short cycle life (≤5 times); single light signal control (such as ultraviolet light only) is easy to counterfeit and has insufficient encryption security; conjugated structure guests are easily oxidized and the fluorescence decays quickly in water and oxygen environments (<30 days).

[0004] In their research, the inventors discovered a host-guest interaction driven internally by a pillar arene macrocycle controlled by ultraviolet and visible light with a photo-inert guest: that is, under ultraviolet light irradiation, the electron-rich pillar arene macrocycle enters an excited state, the polarity of the macrocycle cavity increases, and the electron cloud density at the macrocycle opening undergoes a huge change, resulting in an enhanced internal driving effect of the cavity, which leads to an enhanced interaction with the photo-inert bromoalkylphenazine guest molecule and quenching of the guest molecule fluorescence. After the system relaxes for several hours under visible light, the polarity of the pillar arene cavity weakens, the host-guest interaction with the guest molecule disappears, and the guest fluorescence recovers. Therefore, the present invention proposes the innovative concept of using the change in the electronic state of the electron-rich pillar arene host under light to drive the occurrence and disintegration of the host-guest interaction, thereby obtaining an intelligent light-responsive supramolecular system with a long cycle life, and applying it to application fields such as sustainable sensing separation and encryption materials. This invention is based on the host-guest interaction between differently functionalized pillararenes and photoinert guests driven by ultraviolet light. This light-driven macrocyclic self-propelled host-guest interaction system exhibits a unique UV / visible light alternating response: the system changes from bright blue to black under UV irradiation and back to bright blue under visible light. This invention proposes, for the first time, a self-assembled system based on a photoinert guest (bromophenazine) and a non-conjugated pillararene host, driving the host-guest interaction through UV-induced changes in the host cavity polarity, achieving dual-band reversible control. Summary of the Invention

[0005] The present invention aims to provide a dual-band controlled photoresponsive supramolecular material and its application. By utilizing pillararene macrocycles, driven by ultraviolet light, to undergo photoinduced host-guest interactions with photoinert guest molecules, this approach addresses the limitation of photoresponsive materials primarily relying on guest molecules with significant structural changes, such as photoisomerization. Furthermore, the present invention addresses the limitation of photoresponsive materials being limited by a single stimulus signal source by proposing a multi-stimulus signal response mode controlled by both the macrocycle and ultraviolet light, enhancing the security of encryption and anti-counterfeiting technology. Finally, the present invention addresses the technical difficulty that conventional photoresponsive materials, most of which have large conjugated structures, are easily damaged after multiple photoswitching cycles, resulting in short cycle life and unfavorable sustainable development.

[0006] The dual-band photoresponsive supramolecular material based on pillararenes of the present invention is formed by self-assembly of a pillararene derivative host and a photoinert fluorescent compound guest in an organic solvent in an equimolar ratio; The pillararene derivative is any one of methoxy-homo-pillarene, unilateral 1-bromobutane-functionalized pillararene, bilateral 1-bromobutane-functionalized pillararene, phthalimide-functionalized pillararene, bilateral amino-functionalized pillararene, and phenylthiourea-functionalized pillararene; the optically inert fluorescent compound is 1-bromobutylbenzimidazolephenazine or 1-bromobutylazaquinonephenazine; and the organic solvent is dichloromethane, dichloroethane, or chloroform.

[0007] The structural formula of pillararene derivatives is as follows: H1: methoxy-functionalized pillararene; H2: unilateral 1-bromobutane-functionalized pillararene; H3: phthalimide-functionalized pillararene; H4: bilateral 1-bromobutane-functionalized pillararene; H5: bilateral amino-functionalized pillararene; H6: phenylthiourea-functionalized pillararene; The structural formula of the optically inert fluorescent compound is as follows: G1: 1-bromobutylbenzimidazolephenazine; G2: 1-bromobutylazepinephenazine The present invention's photoresponsive supramolecular materials are used in information encryption or anti-counterfeiting applications. Information encryption is achieved by triggering fluorescence quenching under ultraviolet light, and decryption is achieved by restoring fluorescence under visible light. The encryption process incorporates Morse or ASCII binary encoding for multi-level signal conversion.

[0008] The encryption process is achieved by uniformly depositing the photoresponsive supramolecular material onto a solid template made of filter paper, a silica gel sheet, and a gelatin film. A hollow pattern is then engraved based on the encrypted information and its content. This pattern is then attached to the prepared solid template and uniformly irradiated for 4-10 minutes under a 254nm UV lamp for information storage and encryption. This encrypted information can be stored for a long time, with preliminary tests showing a storage time of over two years, which is crucial for the durability and reliability of information storage in practical applications. The decryption process requires uniform irradiation under visible light for at least 10-12 hours.

[0009] The pillararene derivatives of the present invention can be excited by ultraviolet light in the 254 nm band, resulting in photoinduced excited state charge separation, and instant photoinduced host-guest interaction with the fluorescent guest compound, resulting in instantaneous quenching of the guest molecule's fluorescence. This photoinduced response process is as follows: Figure 1 、 Figure 2 Unlike conventional photoresponse principles, the photoresponse mechanism proposed in this invention is not based on a guest molecule undergoing significant structural changes such as photoisomerization. Instead, it relies on the intrinsic drive effect of the non-fluorescent pillararene macrocycle under ultraviolet light irradiation, inducing charge separation in the photoinert guest molecule's fluorescent group, thereby quenching its fluorescence.

[0010] Supramolecular materials formed by self-assembly of macrocyclic molecules through host-guest interactions naturally possess the characteristics of tightly packed molecular aggregates through electrostatic and π-π stacking interactions. This not only suppresses the vibration and intermolecular relaxation of embedded fluorescent molecules, but also isolates water and oxygen, reducing the external factors that could cause triplet annihilation of excited luminescent molecules, thereby endowing the assembled materials with high photoresponsiveness. Leveraging the unique UV / visible light-controlled response of this photocontrolled macrocyclic internally driven host-guest interaction system, functional materials with multi-strategy photoinduced anti-counterfeiting and encryption properties have been developed. Specifically, upon UV irradiation, the electron cloud density at the opening of the pillararene macrocycle undergoes a dramatic change, enhancing its interaction with the bromoalkylphenazine fluorescent guest molecule, leading to quenching of the guest's fluorescence. However, after several hours of relaxation under visible light, the host-guest interaction disappears, and the guest fluorescence resumes. Based on the fluorescence color response patterns of the host-guest system under alternating UV and visible light irradiation, various anti-counterfeiting and encryption strategies have been developed. The key decryption step is UV irradiation, which allows the stored information to be successfully decrypted.

[0011] Based on the host-guest interaction between the light-driven macrocyclic molecule and the photoinert guest molecule under ultraviolet light irradiation, the guest molecule fluorescence quenching occurs. This photoresponse characteristic has a dual control feature. Unlike conventional photoresponsive switching materials controlled by a single stimulus, dual-control photoresponsive functional materials are controlled by both the macrocyclic molecule and the light stimulus. Without any one of these factors, the photowatermark encryption operation cannot be completed. This is like the "two-person, two-lock" control measure in security regulations. Only when both are present at the same time can the lock be opened correctly. Therefore, based on this outstanding characteristic of the light-controlled assembly material, it has excellent dual confidentiality performance in the field of photowatermark encryption applications, which can not only enhance the security of information storage, but also the pattern information of the photowatermark is formed in one go and is non-replicable. In addition, due to the good photostability of the light-driven pillar aromatic hydrocarbon host-guest interaction, according to our preliminary tests, the information pattern of the photowatermark can be preserved for a long time.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. Breaking through the limitations of traditional photoresponse mechanisms Innovative application of photo-inert guests: Traditional photoresponsive materials (such as azobenzene / cyclodextrin systems) rely on the isomerization of photoactive guests (such as cis-trans isomerization and ring opening and closing reactions). The present invention uses photo-inert fluorescent compounds (such as brominated phenazine) as guests, and drives the host-guest interaction through the change of cavity polarity of the pillar aromatic hydrocarbon host under ultraviolet light excitation to achieve fluorescence regulation.

[0013] Non-conjugated structural stability: The pillar aromatic hydrocarbon main body has no conjugated double bonds, which avoids the problem of easy oxidation and degradation of traditional conjugated structure guests (such as anthracene and spiropyran), significantly improves the photostability of the material, has a long cycle life, and can be recycled at least 10-20 times.

[0014] 2. Dual-band reversible response enhances encryption security UV / visible light dual control: UV light triggers fluorescence quenching (encryption), while visible light irradiation restores fluorescence (decryption), forming a "two-person, double-lock" anti-counterfeiting logic that is more difficult to counterfeit than a single light signal response (such as UV light only).

[0015] Dynamic reversibility: cycle life ≥ 10 times (traditional materials ≤ 5 times), and the response speed and recovery time are controllable (triggered by ultraviolet light irradiation for 4-10 minutes, recovered by visible light for 10-12 hours).

[0016] 3. Excellent practical performance Environmental stability: The hydrophobic fluorescent tag can still be read after being immersed in water for 60 days, far exceeding the fluorescence decay of traditional materials (<30 days). It is suitable for making information encryption materials in underwater, humid or outdoor environments.

[0017] Multi-level encryption compatibility: supports Morse encoding, ASCII binary and other high-level information conversion, and can achieve dual encryption of pattern and digital information through hollow templates.

[0018] 4. Material design and application flexibility Main body diversity: All six functionalized pillar aromatic hydrocarbon derivatives are adaptable, with a large space for modification of the main structure, and the response characteristics can be adjusted according to different needs (such as amino functionalization to enhance water solubility).

[0019] Universality of guests: Photoinert guests (G1 / G2) do not require complex synthesis and are not affected by isomerization side reactions, expanding the boundaries of material design. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Example 1: Schematic diagram of the response of the photoresponsive supramolecular material; Figure 2 Example 2 Schematic diagram of the response of the photoresponsive supramolecular material; Figure 3 Schematic diagram of the application of the photoresponsive supramolecular material of the present invention in photoencryption; FIG4 is a schematic diagram of the application of the photoresponsive supramolecular material of the present invention in Morse coding high-order information encryption; Figure 5 The invention discloses an anti-counterfeiting hydrophobic fluorescent label prepared from a light-responsive supramolecular material. DETAILED DESCRIPTION

[0021] The preparation and application of the photoresponsive supramolecular material of the present invention will be further described below through specific examples.

[0022] Example 1: Photoresponsive supramolecular material with dual-controllable photoresponsiveness constructed from methoxyl homo-pillar aromatic hydrocarbon and 1-bromobutylbenzimidazole phenazine Weigh 0.0015g of methoxyl homoaromatic hydrocarbon and dissolve it in 1mL of dichloromethane solvent to prepare 2×10 -3 mol / L main stock solution for standby use; weigh 0.0008 g of 1-bromobutylbenzimidazole phenazine and dissolve it in 1 mL of dichloromethane solvent to prepare 2×10 -3 mol / L guest stock solution for standby use; then take 0.5 mL of the above-prepared host and guest stock solution, add solvent dichloromethane to make the volume to 5 mL, and obtain 2×10 -4 mol / L host-guest solution; the concentration is 2×10 -4 mol / L of the host and guest solutions were mixed in equal volumes and placed under ultrasound to fully mix to form a photoresponsive supramolecular material. The final concentration of the photoresponsive supramolecular material was 1×10 -4 mol / L.

[0023] like Figure 1 The photoresponsive supramolecular material was irradiated under a 254 nm ultraviolet lamp for 4-10 minutes, and the fluorescence attenuation and fluorescence color change were observed under a 365 nm ultraviolet lamp. It was found that the fluorescence of the photoresponsive supramolecular material was quenched, and the color of the reaction liquid completely changed from yellow-green to dark brown; the fluorescence-quenched supramolecular photoresponsive system was then irradiated under visible light for 10-12 hours, and the fluorescence change of the above system solution was observed under a 365 nm ultraviolet lamp. It was found that the fluorescence returned to its original yellow-green color, realizing dual-band reversible regulation.

[0024] Example 2: Photoresponsive supramolecular material with dual-controllable photoresponsiveness constructed from methoxyl homo-columnarene and 1-bromobutylazaphenazine Weigh 0.0015g of methoxyl homoaromatic hydrocarbon and dissolve it in 1mL of dichloromethane solvent to prepare 2×10 -3 mol / L main stock solution for standby use; weigh 0.0009g of 1-bromobutyl azaphenazine and dissolve it in 1mL of dichloromethane solvent to prepare 2×10 -3 mol / L guest stock solution for standby use; then take 0.6 mL of the above-prepared host and guest stock solution, add solvent dichloromethane to make the volume to 6 mL, and obtain 2×10 -4 mol / L host-guest solution; the concentration is 2×10 -4 mol / L host and guest solutions were mixed in equal volumes and placed under ultrasound to fully mix to form a photoresponsive supramolecular material. The final concentration of the photoresponsive supramolecular material was 1×10 -4 mol / L.

[0025] like Figure 2The photoresponsive supramolecular material was irradiated under a 254 nm ultraviolet lamp for 4-10 minutes, and the fluorescence attenuation and fluorescence color change were observed under a 365 nm ultraviolet lamp. It was found that the fluorescence of the photoresponsive supramolecular material was quenched, and the color of the reaction liquid completely changed from blue-green to dark brown; the fluorescence-quenched supramolecular photoresponsive system was then irradiated under visible light for 10-12 hours, and the fluorescence changes under a 365 nm ultraviolet lamp showed that the fluorescence returned to its original blue-green color, realizing dual-band reversible regulation.

[0026] Example 3 Application of Photoresponsive Supramolecular Materials in Photoencryption The light-responsive supramolecular material solution prepared in Example 2 was loaded onto a gelatin film by a uniform deposition method. The encrypted information pattern and the encrypted content were engraved into a hollow pattern model, which was then attached to the prepared gelatin film and irradiated under 254 nm ultraviolet light for 4-10 minutes to form an encrypted pattern. When decrypting, the film was irradiated under visible light for 10-12 hours (as shown in FIG. Figure 3 ).

[0027] Example 4 Application of Photoresponsive Supramolecular Materials in Morse-Encoded High-Order Information Encryption Morse binary high-order signal coding encryption first requires setting up the encoding program for the encrypted information, and then placing the guest molecule 1-bromobutylazaphenazine solution (2×10 -4 mol / L) was placed in the porous template matrix in advance, and the corresponding text or graphics were drawn according to the encrypted pattern and text information. Then, the methoxyl homoaromatic hydrocarbon main solution (2×10 -4 mol / L) according to the outline of the designed text pattern, add it to the corresponding porous template, and finally irradiate the encrypted material under 254 nm ultraviolet light for encryption. If the encrypted pattern is incomplete or unclear, continue the above steps until it is complete and clear. Irradiate under visible light for 10-12 hours to decrypt the pattern information, and analyze the decrypted content. The specific implementation diagram is shown in the figure below. Figure 4 shown.

[0028] Example 5 Preparation of anti-counterfeiting hydrophobic fluorescent label The light-responsive supramolecular material solution prepared in Example 2 is used as an encryption liquid. A writable soft material (which can be a matrix such as polyester clothing, paper, glass, silica gel plate or film) is used to write the text and pattern information to be encrypted on the soft material matrix. The matrix is then placed under a 365 nm ultraviolet lamp to observe whether the pattern information written on the solid matrix is complete and clear. This operation can be repeated multiple times until a complete and clear pattern appears on the soft material matrix. The encrypted writing is then performed under 254 nm ultraviolet light for 4-10 minutes to prepare the corresponding fluorescent label. The fluorescent label material is then placed under a 254 nm ultraviolet lamp for 10 minutes. The fluorescent material matrix printed with text or pattern is then placed in deionized water for 1 day, 3 days, 5 days, 7 days, 1 meter, and 2 meters. The fluorescent label material immersed in deionized water is observed and recorded, as shown in FIG. Figure 5 The picture shown is a picture of the fluorescent label material being immersed in deionized water for 2 months. The text pattern on the fluorescent label is still clearly visible, and there is no dissolution phenomenon, indicating that the fluorescent label we prepared has anti-counterfeiting hydrophobic properties.

Claims

1. A dual-band photoresponsive supramolecular material based on pillararenes, characterized by: It is formed by self-assembly of a pillararene derivative host and a photoinert fluorescent compound guest in an organic solvent at an equimolar ratio; The pillararene derivative is any one of methoxyl homo-pillararene, unilateral 1-bromobutane functionalized pillararene, bilateral 1-bromobutane functionalized pillararene, phthalimide functionalized pillararene, bilateral amino functionalized pillararene, and phenylthiourea functionalized pillararene; The optically inert fluorescent compound is 1-bromobutylbenzimidazolephenazine or 1-bromobutylazepinephenazine.

2. The dual-band photoresponsive supramolecular material according to claim 1, wherein: The organic solvent is dichloromethane, dichloroethane or chloroform.

3. The dual-band photoresponsive supramolecular material according to claim 1, wherein: The material undergoes host-guest interaction under 254 nm ultraviolet light irradiation, resulting in fluorescence quenching, and recovers fluorescence under visible light irradiation, achieving reversible response in the ultraviolet / visible light dual bands.

4. Application of the dual-band light-responsive supramolecular material according to claim 1 in information encryption or anti-counterfeiting, characterized in that: Information encryption is achieved by triggering fluorescence quenching by ultraviolet light irradiation, and decryption is achieved by restoring fluorescence by visible light irradiation.

5. The use according to claim 4, characterized in that: Encrypting information is accomplished through the following steps: (1) Loading supramolecular materials onto filter paper, silica gel plate, or gelatin film; (2) After covering the hollow pattern template, irradiate under 254nm ultraviolet light for 4-10min to form an encrypted pattern; (3) During decryption, the fluorescence is restored by irradiating the sample with visible light for 10-12 hours, and the decrypted pattern is observed under 365nm ultraviolet light.

6. The use according to claim 4, characterized in that: The encrypted information can be reversibly restored to its initial state under visible light, with a cycle life of ≥10 times.

7. The use according to claim 4, characterized in that: The hydrophobic fluorescent tag formed by the material can still be read after being immersed in water for 60 days.

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