A luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters, and a preparation method and application thereof

Abstract

The application belongs to the technical field of inorganic-organic hybrid luminescent anti-counterfeiting materials, and discloses a luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters as well as a preparation method and application thereof. The luminescent anti-counterfeiting ink is prepared by dissolving cuprous iodide in a saturated potassium iodide solution to obtain a copper source precursor solution, dissolving diphenyl-2-pyridyl phosphine in anhydrous ethanol to obtain a ligand solution, and then adding polyvinylpyrrolidone solution and the ligand solution into the copper source precursor solution in sequence and stirring to react, so as to obtain copper-iodine hybrid clusters. The copper-iodine hybrid clusters are dispersed in anhydrous ethanol to obtain the luminescent anti-counterfeiting ink, and the molecular formula of the copper-iodine hybrid clusters is C 51 H 51 Cu2I2N3P3, and the structure is shown in formula (I). The luminescent anti-counterfeiting ink has a photoluminescence quantum yield of 90.1% after being excited by 365 nm ultraviolet light, has high luminescent efficiency and good stability, and has no agglomeration and sedimentation phenomenon, and can be applied in the fields of anti-counterfeiting printing and large-area film forming.

Description

Technical Field

[0001] This invention belongs to the technical field of inorganic-organic hybrid luminescent anti-counterfeiting materials, specifically relating to a luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters, its preparation method, and its application. Background Technology

[0002] With rapid economic development and increasingly frequent commodity circulation, counterfeit and substandard goods are rampant in the market. This not only seriously disrupts normal market order but also damages corporate brand reputation and consumer rights. Therefore, the application of anti-counterfeiting technology is becoming increasingly important in the modern packaging and document printing fields. It can not only effectively strengthen brand protection but also regulate market order and ensure the sustainable development of enterprises and society. Among these, ink-based anti-counterfeiting technology, due to its advantages such as controllable cost, flexible identification, and ease of implementation, has become one of the most mature and widely used anti-counterfeiting methods in the fields of documents, securities, and high-end product packaging.

[0003] The core principle of anti-counterfeiting ink technology is to add functional substances with special physical or chemical properties (such as magnetic substances, infrared absorbing substances, luminescent substances, etc.) to special ink binders. These substances are then combined with special processing techniques and anti-counterfeiting printing processes to prepare specialized inks with anti-counterfeiting functions. Among these, luminescent substances, due to their advantages such as intuitive visual recognition, strong anti-counterfeiting concealment, and the ability to achieve multi-parameter encoding, have become the core functional component for enhancing the level of anti-counterfeiting inks and are widely used in high-end anti-counterfeiting fields.

[0004] Currently, commonly used luminescent anti-counterfeiting materials on the market still suffer from numerous technical defects, limiting their large-scale promotion. Existing anti-counterfeiting materials mainly include multi-element anti-counterfeiting coding functional materials, semiconductor quantum dots, and rare earth complexes. Among them, rare earth complexes and quantum dots contain heavy metal components. The photoluminescence quantum yield of rare earth complexes is generally below 60%, and the heavy metal content of Cd-based quantum dots exceeds 1000 ppm, failing to meet environmental standards such as EU RoHS. Moreover, their preparation processes often use organic solvent systems, which are unfriendly to health and the environment, have high raw material prices, and involve complicated synthesis steps. Furthermore, they are prone to performance degradation under the influence of environmental factors such as light, heat, and humidity, resulting in insufficient reliability during long-term use. Multi-element anti-counterfeiting coding functional materials, on the other hand, suffer from complex synthesis steps and poor environmental compatibility. The integration of their multiple functional units involves technical challenges such as interface control and energy matching, which can easily lead to mutual interference, thus restricting their performance and hindering large-scale preparation and application. Therefore, it is crucial to develop a new type of luminescent material that is environmentally friendly, has a simple preparation process, is low in cost, and has stable performance for the anti-counterfeiting field.

[0005] Copper-iodine hybrid clusters, as a novel luminescent material, possess significant technological advantages in anti-counterfeiting applications. Their synthesis is simple, they are abundant in the Earth's crust, the raw materials are inexpensive, and they exhibit excellent luminescent properties, making them suitable for large-scale, low-cost anti-counterfeiting applications. Furthermore, they do not contain highly toxic heavy metals or rare earth elements, have low toxicity, and excellent environmental compatibility, demonstrating great application potential in the anti-counterfeiting field. However, existing reports on this type of material often suffer from poor dispersibility, poor film-forming properties, and a tendency to aggregate and settle, making them unsuitable for direct adaptation to conventional printing processes and limiting their practical application in the field of anti-counterfeiting inks. Summary of the Invention

[0006] To address the shortcomings and drawbacks of existing technologies, and considering the common technical defects in luminescent materials used in anti-counterfeiting inks, such as poor environmental compatibility, complex preparation processes, high raw material costs, and insufficient long-term performance stability, the primary objective of this invention is to provide a method based on copper-iodine hybrid clusters (C... 51 H 51 A luminescent anti-counterfeiting ink (Cu2I2N3P3) is presented. This yellow-green luminescent anti-counterfeiting ink exhibits good dispersibility and excellent film-forming properties, meeting the application requirements of an ideal anti-counterfeiting ink.

[0007] Another objective of this invention is to provide a method for preparing the aforementioned luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters. This method possesses advantages such as good stability, low cost, environmental friendliness, and simple preparation method.

[0008] Another object of the present invention is to provide the application of the above-mentioned luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters. This luminescent anti-counterfeiting ink can be directly used for printing and has broad industrial application potential in the field of new environmentally friendly luminescent anti-counterfeiting materials. It can be widely used in anti-counterfeiting fields such as certificates, securities, and high-end product packaging.

[0009] The objective of this invention is achieved through the following technical solution: A luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters is prepared by dissolving cuprous iodide in a saturated potassium iodide solution to obtain a copper-based precursor solution; dissolving a nitrogen- and phosphorus-containing bidentate ligand in anhydrous ethanol to obtain a ligand solution; then sequentially adding the copper-based precursor solution and the ligand solution to a water-soluble or alcohol-soluble polymer solution and stirring the reaction. After the reaction is complete, centrifugation and washing are performed to obtain copper-iodine hybrid clusters. These copper-iodine hybrid clusters are then dispersed in anhydrous ethanol. The molecular formula of the copper-iodine hybrid clusters is C0. 51 H 51 Cu2I2N3P3, its structure is shown in equation (Ⅰ): Equation (Ⅰ).

[0010] Preferably, the molar ratio of cuprous iodide to diphenyl-2-pyridylphosphine is (0.9~1.1):1.

[0011] Preferably, the concentration of the copper source precursor solution is 0.5~0.55 mmol / mL; the mass ratio of the amount of nitrogen- and phosphorus-containing bidentate ligands in the ligand solution to the volume of anhydrous ethanol is (1~1.1) mmol:2 mL; and the nitrogen- and phosphorus-containing bidentate ligands in the ligand solution are diphenyl-2-pyrimidinylphosphine, diphenyl-2-pyridinylphosphine, or diphenyl-2-pyrazinylphosphine.

[0012] Preferably, the volume ratio of the water-soluble or alcohol-soluble polymer solution, the ligand solution, and the copper source precursor solution is 100:(0.5~0.6):(1~1.1).

[0013] Preferably, the water-soluble or alcohol-soluble polymer solution is an anhydrous ethanol solution of polyvinylpyrrolidone, an aqueous solution of polyvinyl alcohol, or an anhydrous ethanol solution of polyacrylate; the mass ratio of the water-soluble or alcohol-soluble polymer to the volume ratio of anhydrous ethanol or water is (1~1.1) g:100 mL.

[0014] Preferably, the mass ratio of the copper-iodine hybrid cluster to the volume ratio of anhydrous ethanol is (1.1~1.4) g:100 mL.

[0015] The method for preparing the luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters includes the following steps: S1. Dissolve cuprous iodide in a saturated potassium iodide solution to obtain a copper precursor solution; dissolve a bidentate ligand containing nitrogen and phosphorus in anhydrous ethanol to obtain a ligand solution; S2. A water-soluble or alcohol-soluble polymer solution and a ligand solution are sequentially added to a copper-based precursor solution and stirred to react. After the reaction is complete, the mixture is centrifuged and washed to obtain copper-iodine hybrid clusters. The copper-iodine hybrid clusters are then dispersed in anhydrous ethanol to prepare a luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters.

[0016] Preferably, the temperature of the stirring reaction in step S2 is 15~35℃, and the stirring reaction time is 4~16h.

[0017] Preferably, the washing solution in step S2 is saturated potassium iodide, deionized water and anhydrous ethanol in sequence; the centrifugation rate is 4000~6000 rpm and the centrifugation time is 3~5 min.

[0018] The application of the luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters in the fields of anti-counterfeiting printing or large-area film formation.

[0019] This invention employs copper-iodine hybrid clusters (C 51 H 51Cu₂I₂N₃P₃ is used as the luminescent functional component. Clusters are relatively stable microscopic or submicroscopic aggregates composed of several to thousands of atoms, molecules, or ions bound together by physical or chemical forces. With Cu₂I₂ as the inorganic core, copper atoms coordinate with nitrogen- and phosphorus-containing ligands to form stable dimer cluster structures, a structure distinct from existing rare-earth luminescent materials and quantum dot materials. Without affecting the cluster stability, water-soluble or alcohol-soluble polymers (such as polyvinylpyrrolidone, polyvinyl alcohol, or polyacrylate) are used as stable dispersion systems to obtain anti-counterfeiting inks suitable for different printing processes. Without altering the inorganic core structure and coordination mode of Cu₂I₂, bidentate ligands containing nitrogen and phosphorus (such as diphenyl-2-pyridylphosphine, diphenyl-2-pyrimidinylphosphine, diphenyl-2-pyrazinylphosphine, etc.) are used as ligands to regulate the luminescent color of the cluster material, achieving anti-counterfeiting coding.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention is based on C 51 H 51 The yellow-green luminescent anti-counterfeiting ink of Cu2I2N3P3 is prepared by dispersing the copper-iodine hybrid cluster as the luminescent functional component in a polymeric stable dispersion system. When the polymeric stable dispersion system is a polyvinylpyrrolidone (PVP) ethanol system, the resulting anti-counterfeiting ink is colorless and transparent or nearly transparent. After being excited by 365nm ultraviolet light, it exhibits a single-width emission peak covering 500~700nm, with a photoluminescence quantum yield as high as 90.1%, which is significantly better than traditional rare earth complexes (generally below 60%) and semiconductor quantum dot luminescent materials. It solves the problems of poor dispersibility and poor film-forming properties of existing copper-iodine hybrid cluster materials, and can be directly used in various processes such as writing, inkjet printing, and scraping film formation.

[0021] 2. This invention uses C 51 H 51 The Cu₂I₂N₃P₃ cluster serves as the luminescent functional component. This structure uses Cu₂I₂ as the inorganic core, with copper atoms coordinating with nitrogen and phosphorus atoms on the ligands to form a stable and unique dimer spatial configuration. Relevant crystal structure data can be used to confirm the composition and structural characteristics of this luminescent functional component. This copper-iodine hybrid cluster exhibits a high thermal decomposition temperature of 228.5℃, maintaining dual stability in both structure and luminescent properties within the typical printing and operating temperature range.

[0022] 3. This invention employs a simple one-step room-temperature liquid-phase synthesis method, which eliminates the need for high-temperature and high-pressure equipment, inert gas protection, and cumbersome post-processing procedures. The synthesis route is simple, the reaction conditions are mild, and the raw materials used are readily available and have low toxicity. It can achieve large-scale preparation of more than 50 grams, effectively solving the technical bottlenecks of high synthesis cost, high toxicity, and complex synthesis steps of traditional rare earth luminescent materials and quantum dot materials. The preparation cost is significantly reduced, and it has good prospects for industrialization.

[0023] 4. This invention is the first to apply a copper-iodine hybrid cluster system to the field of anti-counterfeiting inks, achieving an organic combination of ultraviolet excitation display and printability. The overall solution avoids the problems of high cost, complex preparation, and heavy environmental impact of traditional anti-counterfeiting luminescent materials, while taking into account luminous efficiency, stability, and practical application feasibility, making it suitable for applications such as anti-counterfeiting labels, packaging printing, and information concealment.

[0024] 5. The present invention is based on C 51 H 51 Cu2I2N3P3 luminescent anti-counterfeiting ink has high luminous efficiency, good stability, and no agglomeration or sedimentation. It is compatible with various conventional printing and film-forming processes such as screen printing, inkjet printing, scraping, and spin coating, and can meet the application needs of different anti-counterfeiting scenarios.

[0025] 6. The present invention is based on C 51 H 51 The Cu2I2N3P3 anti-counterfeiting ink was stored at room temperature away from light, and its photoluminescence performance was tested after 1 day, 6 months, and 12 months of storage to evaluate its long-term performance. The results showed that the emission spectrum shape of the samples remained largely consistent across different storage times, with a peak shift of less than 2 nm. Simultaneously, the luminescence intensity showed no significant attenuation and remained at a high level, confirming that the material possesses excellent storage stability and can meet the requirements for use throughout the product's entire lifecycle. Attached Figure Description

[0026] Figure 1 C prepared in Example 1 51 H 51 Schematic diagram of the unit cell structure of Cu2I2N3P3 single crystal; Figure 2 C prepared in Example 1 51 H 51 A comparison of the X-ray diffraction (XRD) pattern of Cu2I2N3P3 single crystal with the simulated standard XRD pattern of single crystal; Figure 3 The C-based preparation of Example 2 51 H 51 Comparison of real photos of Cu2I2N3P3 anti-counterfeiting ink under natural light (left) and 365nm ultraviolet light (right); Figure 4 The C-based preparation of Example 2 51 H 51 UV excitation and emission spectra of anti-counterfeiting ink for Cu2I2N3P3; Figure 5 The C-based preparation of Example 2 51 H 51 Thermogravimetric analysis curve of anti-counterfeiting ink of Cu2I2N3P3; Figure 6 The C-based preparation of Example 2 51 H 51 Emission spectrum and photoluminescence quantum yield variation curve of Cu2I2N3P3 anti-counterfeiting ink under different storage times; Figure 7 The image shows a comparison of the anti-counterfeiting printing pattern of Application Example 1 under natural light (left) and 365nm ultraviolet light (right). Figure 8 For example 2, the loaded copper-iodine hybrid cluster (C 51 H 51 The luminescence effect of the anti-counterfeiting luminescent film (Cu2I2N3P3) under 365nm ultraviolet light irradiation. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0028] The raw materials and solvents used in this embodiment are all commercially available products: cuprous iodide (CuI, Aladdin Reagent Co., Ltd., 99.95%), potassium iodide (KI, Sinopharm Chemical Reagent Co., Ltd., analytical grade), diphenyl-2-pyridylphosphine (ACMEC, 97%), anhydrous ethanol (Guangzhou Huasheng Chemical Technology Co., Ltd., analytical grade), polyvinylpyrrolidone (PVP, Maclean Reagent Co., Ltd., K88-96), polyvinylpyrrolidone (PVP, Aladdin Reagent Co., Ltd., K30), acetonitrile (Maclean Reagent Co., Ltd., chromatographic grade), and toluene (Sinopharm Chemical Reagent Co., Ltd., analytical grade).

[0029] Example 1 C 51 H 51 Preparation of Cu2I2N3P3 single crystals 1. Dissolve 0.635 g of potassium iodide in 0.5 mL of deionized water and stir thoroughly at room temperature until completely dissolved; add 0.04975 g (0.25 mmol) of cuprous iodide and continue stirring until the cuprous iodide is completely dissolved to obtain a copper source precursor solution; 2. Dissolve 131.5 mg of diphenyl-2-pyridylphosphine (0.5 mmol) in 1 mL of toluene and stir thoroughly at room temperature until completely dissolved to obtain a ligand solution; 3. Preparation of C using liquid layer diffusion method 51 H 51 Cu2I2N3P3 single crystal: Transfer the copper source precursor solution to the bottom of a 10mL glass bottle, slowly add 3mL of acetonitrile along the bottle wall as an intermediate diffusion layer, and then slowly add a low-density ligand solution along the wall to form a clear liquid layer on top. During the interfacial liquid addition process, avoid disturbing the lower layer solution to ensure a stable and clear diffusion interface between the good solvent phase and the poor solvent phase. 4. After sealing the system with sealing film, place it in a room-temperature, light-proof, vibration-free environment for static incubation to allow the good solvent and the poor solvent to slowly diffuse at the interface. Incubate for 1-4 weeks, observing well-formed C₂ at the liquid interface or the bottom of the container. 51 H 51 Cu₂I₂N₃P₃ single crystals. Crystals of suitable size, with good transparency and no obvious cracks were selected for subsequent single-crystal X-ray diffraction structure analysis and related crystallographic data testing.

[0030] The C prepared in this embodiment was analyzed using a four-circle single-crystal X-ray diffractometer (SCXRD). 51 H 51 The crystal structure of Cu2I2N3P3 single crystal was tested and analyzed, such as... Figure 1 As shown. The luminescent core material C 51 H 51 XRD patterns of Cu₂I₂N₃P₃ single crystals and simulated XRD patterns of single crystals, such as Figure 2 As shown, the C prepared by it 51 H 51 Cu2I2N3P3 single crystals have high phase purity.

[0031] A suitable crystal was selected and applied to a Bruker D8 VENTURE TXS PHOTON II photonic diffractometer. The C2 crystal prepared in this embodiment was subjected to diffractometer testing at 293 K. 51 H 51 The crystallographic data obtained from the determination of Cu2I2N3P3 single crystals are shown in Table 1.

[0032] Table 1. C prepared in Example 151 H 51 Crystallographic data of Cu2I2N3P3 single crystal

[0033] Example 2 C 51 H 51 Preparation of Cu2I2N3P3 yellow-green luminescent anti-counterfeiting ink 1. Dissolve 1g of PVP in 100mL of anhydrous ethanol and stir at 600rpm for more than 30min until completely dissolved to obtain a PVP ethanol solution; 2. Dissolve 1.27 g of potassium iodide in 0.5 mL of deionized water and stir until completely dissolved. Then add 0.095 g (0.5 mmol) of cuprous iodide and continue stirring until the cuprous iodide is completely dissolved to obtain a copper source precursor solution. 3. Dissolve 131.5 mg (0.5 mmol) of diphenyl-2-pyridylphosphine in 1 mL of anhydrous ethanol and stir until completely dissolved to obtain the ligand solution; 4. The copper precursor solution and ligand solution were filtered separately to remove insoluble impurities. Then, they were slowly added dropwise to the PVP ethanol solution and stirred thoroughly at 600 rpm for 12 hours. The solutions were then separated and washed sequentially with saturated potassium iodide, deionized water, and anhydrous ethanol at 4500 rpm for 3 minutes to obtain homogeneous and stable copper-iodine hybrid clusters (C...). 51 H 51 Luminescent anti-counterfeiting ink (Cu2I2N3P3).

[0034] Figure 3 The C-based preparation of Example 2 51 H 51 Photos of the anti-counterfeiting ink for Cu2I2N3P3 under natural light (left) and 365nm ultraviolet light (right). (Source: [Insert Source Here]) Figure 3 It can be seen that the anti-counterfeiting ink exhibits a uniform, transparent or nearly transparent dispersion under natural light irradiation, with no obvious precipitation, flocculation, or agglomeration observed. Under 365nm ultraviolet light irradiation, the system emits bright and uniform yellow-green fluorescence, indicating that the material has excellent dispersibility and yellow-green luminescence characteristics under ultraviolet light excitation. The C-based anti-counterfeiting ink prepared in this embodiment was analyzed using an Edinburgh Instruments Ltd. (EI) FLS980 steady-state transient fluorescence spectrometer. 51 H 51 The anti-counterfeiting ink of Cu2I2N3P3 was tested for emission and excitation spectra. Figure 4 The C-based preparation of Example 2 51 H 51The ultraviolet excitation and emission spectra of Cu2I2N3P3 anti-counterfeiting ink are shown. Ex represents the highest absorption peak in the excitation spectrum, and Em represents the highest peak in the emission spectrum. Figure 4 It can be seen that the anti-counterfeiting ink has a significant excitation response in the ultraviolet region, with its maximum emission peak located in the yellow-green luminescent region. The emission spectrum exhibits broadband emission characteristics and high emission intensity, indicating that the material has broadband emission characteristics in the 500-700 nm range under ultraviolet light excitation. The thermal stability of the anti-counterfeiting ink was tested using a thermogravimetric analyzer (TGA / DSC3+thermal gravimetric analyzer). Figure 5 The C-based preparation of Example 2 51 H 51 Thermogravimetric analysis curve of anti-counterfeiting ink of Cu2I2N3P3. Figure 5 It can be seen that C 51 H 51 The thermal decomposition temperature of Cu2I2N3P3 is as high as 228℃, indicating that the anti-counterfeiting ink has good thermal stability.

[0035] To further evaluate the results based on C 51 H 51 The storage stability of the anti-counterfeiting ink of Cu2I2N3P3 was investigated by storing the anti-counterfeiting ink prepared in Example 2 at room temperature and in the dark for a long period of time, and testing its emission spectrum and photoluminescence quantum yield after 1 day, 6 months and 12 months of storage. Figure 6 The C-based preparation of Example 2 51 H 51 The emission spectrum and photoluminescence quantum yield variation curves of Cu2I2N3P3 anti-counterfeiting ink under different storage times. For example... Figure 6 As shown, the emission spectrum morphology of the samples remained basically consistent under different storage times, the position of the emission peak did not shift significantly, and the photoluminescence quantum yield remained at a high level. This indicates that the anti-counterfeiting ink has good optical stability and dispersion stability during long-term storage, which can meet the requirements of actual anti-counterfeiting printing products for long-term service reliability.

[0036] Application Example 1 C 51 H 51 Cu2I2N3P3 anti-counterfeiting ink printing pattern The C-based material obtained in Example 2 51 H 51The anti-counterfeiting ink made of Cu2I2N3P3 was subjected to thorough agitation for 5 minutes, followed by ultrasonic treatment (100W power) for 10 minutes to form a uniform dispersion system. The anti-counterfeiting ink was then loaded into an inkjet printing reservoir and printed using tracing paper as the printing substrate according to a preset pattern. After printing, the ink was allowed to dry naturally at room temperature in the dark to allow the ethanol solvent to fully evaporate, resulting in an anti-counterfeiting printed pattern with UV-responsive properties.

[0037] Figure 7 The images show a comparison of the anti-counterfeiting printing pattern obtained in Example 1 under natural light (left) and 365nm ultraviolet light (right). Figure 7 It can be seen that the obtained anti-counterfeiting printed pattern has no obvious visible color under natural light, but under 365nm ultraviolet light, the printed area shows a bright and clear yellow-green glow. The glowing area is basically consistent with the preset printed pattern, indicating that the anti-counterfeiting ink can be used for invisible marking and ultraviolet identification.

[0038] Application Example 2 C 51 H 51 Cu2I2N3P3 anti-counterfeiting ink large-area luminescent film 1. Weigh 3g of polyvinylpyrrolidone (preferably PVP-K30) and add it to 5mL of anhydrous ethanol to form a mixed system. Stir at room temperature for 2h to obtain a PVP-ethanol mixture. 2. Mix 1 mL of PVP / ethanol film-forming solution with 1 mL of C prepared in Example 2. 51 H 51 The Cu2I2N3P3 anti-counterfeiting ink was mixed and thoroughly shaken, then ultrasonically dispersed (100W power) for 10 minutes to allow the C... 51 H 51 The Cu2I2N3P3 anti-counterfeiting ink is uniformly fused with the PVP film-forming system to obtain a C-based... 51 H 51 The anti-counterfeiting ink coating liquid of Cu2I2N3P3; 3. Select a glass slide as the film-forming substrate, use anhydrous ethanol to ultrasonically treat the substrate surface for 15 minutes to remove surface oil and impurities, then blow dry the surface solvent with high-purity nitrogen, and then treat with ozone for 15 minutes to improve the hydrophilicity of the substrate surface to obtain a clean substrate. 4. Smooth and fix the cleaned substrate onto the coating platform, and take 1.5 mL of C-based solution. 51 H 51 The anti-counterfeiting ink of Cu2I2N3P3 is applied by dripping a drop of the coating liquid onto one end of the substrate. A scraper is then used to scrape the ink onto the substrate surface at a uniform speed in one direction, so that the coating liquid forms a continuous wet film on the substrate surface. During the scraping process, the gap between the scraper and the substrate is controlled at 0.1 mm, and the scraping speed is controlled at 20 mm / s. 5. After the coating is completed, the resulting wet film is left to cure at room temperature in the original coating position for 30 seconds to allow the wet film to initially set. Then, the substrate carrying the wet film is slightly moved horizontally to remove it from the original coating position to avoid localized adhesion or solvent retention at the bottom of the wet film, which could affect the uniformity of subsequent curing. The film is then left to cure at room temperature for another 3 minutes. Once the film has basically set, it is transferred to a clean, dust-free environment and allowed to air dry at room temperature for 24 hours to remove residual solvent, yielding copper-iodine hybrid clusters (C...). 51 H 51 Anti-counterfeiting luminescent film (Cu2I2N3P3).

[0039] Figure 8 For the load C in application example 2 51 H 51 The luminescence effect of the Cu2I2N3P3 anti-counterfeiting luminescent film under 365nm ultraviolet light irradiation. Figure 8 It can be seen that under ultraviolet light excitation at a wavelength of 365 nm, the film exhibits a uniform yellow-green luminescence, and the luminescent area is basically consistent with the coated area, without obvious dark spots or uneven luminescence. The results indicate that by introducing a PVP-K30 / ethanol film-forming mixture, the film-forming continuity and coating adaptability of the copper-iodine hybrid cluster luminescent anti-counterfeiting ink can be improved. Example 2 shows the preparation of a C-based... 51 H 51 When Cu2I2N3P3 anti-counterfeiting ink is combined with a PVP film-forming system, it can form a continuous and uniform luminescent film on a glass substrate surface through a blade coating process. This film exhibits good concealment under natural light and a distinct and uniform yellow-green luminescence response under 365nm ultraviolet light excitation, indicating that the anti-counterfeiting ink possesses good processability, film-forming properties, and luminescence uniformity, making it suitable for applications such as anti-counterfeiting coatings, invisible markings, large-area anti-counterfeiting pattern preparation, and anti-counterfeiting printing on packaging surfaces.

[0040] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters, characterized in that, The luminescent anti-counterfeiting ink is prepared by dissolving cuprous iodide in a saturated potassium iodide solution to obtain a copper source precursor solution; and by dissolving a nitrogen- and phosphorus-containing bidentate ligand in anhydrous ethanol to obtain a ligand solution. The copper precursor solution and ligand solution are then added sequentially to a water-soluble or alcohol-soluble polymer solution and stirred to react. After the reaction is complete, centrifugation and washing are performed to obtain copper-iodine hybrid clusters. These copper-iodine hybrid clusters are then dispersed in anhydrous ethanol to obtain the final product. The molecular formula of the copper-iodine hybrid clusters is C0. 51 H 51 Cu2I2N3P3, its structure is shown in equation (Ⅰ): Equation (Ⅰ).

2. The luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 1, characterized in that, The molar ratio of cuprous iodide to diphenyl-2-pyridylphosphine is (0.9~1.1):

1.

3. The luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 1, characterized in that, The concentration of the copper precursor solution is 0.5~0.55 mmol / mL; the mass ratio of the amount of nitrogen- and phosphorus-containing bidentate ligands in the ligand solution to the volume of anhydrous ethanol is (1~1.1) mmol:2 mL; the nitrogen- and phosphorus-containing bidentate ligands in the ligand solution are diphenyl-2-pyrimidinylphosphine, diphenyl-2-pyridinylphosphine, or diphenyl-2-pyrazinylphosphine.

4. The luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 1, characterized in that, The volume ratio of the water-soluble or alcohol-soluble polymer solution, ligand solution, and copper source precursor solution is 100:(0.5~0.6):(1~1.1).

5. The luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 1, characterized in that, The water-soluble or alcohol-soluble polymer solution is an anhydrous ethanol solution of polyvinylpyrrolidone, an aqueous solution of polyvinyl alcohol, or an anhydrous ethanol solution of polyacrylate; the mass ratio of the water-soluble or alcohol-soluble polymer to the volume ratio of anhydrous ethanol or water is (1~1.1) g:100 mL.

6. The luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 1, characterized in that, The mass ratio of the copper-iodine hybrid cluster to the volume ratio of anhydrous ethanol is (1.1~1.4) g:100 mL.

7. The method for preparing luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Dissolve cuprous iodide in a saturated potassium iodide solution to obtain a copper precursor solution; dissolve a bidentate ligand containing nitrogen and phosphorus in anhydrous ethanol to obtain a ligand solution; S2. The copper precursor solution and ligand solution are added sequentially to a water-soluble or alcohol-soluble polymer solution and stirred to react. After the reaction is completed, the mixture is centrifuged and washed to obtain copper-iodine hybrid clusters. The copper-iodine hybrid clusters are dispersed in anhydrous ethanol to prepare a luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters.

8. The method for preparing luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 7, characterized in that, The temperature of the stirring reaction in step S2 is 15~35℃, and the stirring reaction time is 4~16h.

9. The method for preparing luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters according to claim 7, characterized in that, The washing solution in step S2 is, in sequence, saturated potassium iodide, deionized water and anhydrous ethanol; the centrifugation rate is 4000~6000 rpm and the centrifugation time is 3~5 min.

10. The application of the luminescent anti-counterfeiting ink based on copper-iodine hybrid clusters as described in any one of claims 1-6 in the fields of anti-counterfeiting printing or large-area film formation.

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