A counter-cas organic long afterglow material and a preparation method and application thereof

Abstract

This invention relates to the field of functional materials technology, and discloses an anti-Kasha organic long-afterglow material, its preparation method, and its applications. The anti-Kasha organic long-afterglow material provided by this invention precisely reconstructs the excited-state energy levels of guest molecules through a sulfur oxidation strategy. Using melamine-formaldehyde resin as a rigid matrix, a pure organic long-afterglow material system with both high quantum yield and anti-Kasha type multiple phosphorescence emission is successfully constructed. Compared with the unoxidized system, the singlet-triple bandgap of the oxidized molecules is significantly reduced from 1.264 eV to 0.944 eV, significantly enhancing the intersystem crossing efficiency. At the optimal doping concentration, a phosphorescence quantum yield of up to 63.1% and a total quantum yield of 88.5% are achieved. Furthermore, the oxidized molecules form a dense multi-triple energy level layout, effectively suppressing the internal conversion from the high-energy triplet state to the lowest triplet state in the rigid matrix. For the first time in this type of system, anti-Kasha type multiple room-temperature phosphorescence emission precisely tunable by the excitation wavelength is achieved.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, and in particular to an anti-Kasha organic long afterglow material, its preparation method, and its application. Background Technology

[0002] Organic long-afterglow materials, especially pure organic room-temperature phosphorescent materials, have become a research hotspot in materials science in recent years due to their enormous application potential in cutting-edge fields such as information encryption, anti-counterfeiting, bioimaging, optoelectronic devices, and 3D printing. Compared with traditional inorganic or metal complex phosphorescent systems that rely on precious metals or rare earth elements, pure organic long-afterglow materials have significant advantages such as low toxicity, flexible synthesis routes, easy modification of molecular structures, and controllable raw material costs, opening up a new path for developing high-performance luminescent materials that conform to the concept of sustainable development.

[0003] However, the development of purely organic room-temperature phosphorescent materials has long faced two major challenges, which severely restrict their progress from the laboratory to practical applications. First, due to the spin-forbidden nature of triplet excitons and their susceptibility to nonradiative quenching, achieving high-efficiency phosphorescence emission is extremely difficult, and long lifetime and high quantum yield are often mutually exclusive. Second, the luminescence behavior of most phosphorescent materials generally follows Kasha's rule, which states that photoluminescence of molecules always occurs from their lowest excited singlet or lowest excited triplet state, regardless of the wavelength of the initial excitation light. That is, luminescence only occurs in the lowest excited state, which fundamentally limits the ability to multidimensionally control the luminescence mode. This makes the photophysical properties of the material, such as emission color and lifetime, usually fixed and difficult to dynamically adjust.

[0004] In recent years, a few anti-Kasha phosphorescent materials that violate the Kasha rule have attracted attention due to their unique excited-state dynamics and potential applications in multidimensional anti-counterfeiting and smart response, but related reports are extremely limited. Research on achieving high quantum yield, anti-Kasha emission, and tunable excitation wavelength simultaneously in a single material system is even rarer. For example, He et al. achieved dual phosphorescence emission and white light through molecular design, but their phosphorescence quantum yield was only 7.2%, indicating low efficiency. Furthermore, their luminescence mechanism relied on the thermal equilibrium population of heavy halogen atoms and T1-T2, limiting controllability. Zhang et al. achieved anti-Kasha-type emission with excitation wavelength control, but this system was based on fluorescence, not phosphorescence, and its molecular structure depended on complex macrocyclic synthesis, increasing preparation difficulty and cost. In the more relevant research on thiophene derivative phosphorescent materials, Xie et al. achieved a phosphorescence efficiency of 29.79%, but did not observe anti-Kasha-type emission in their system. Wu et al. systematically studied the effect of sulfur oxidation on room-temperature phosphorescence, finding that after sulfur atom oxidation, the phosphorescence lifetime of the material significantly increased from 123 ms to 705 ms, demonstrating the great potential of the sulfur oxidation strategy in controlling excited-state energy levels. However, the phosphorescence quantum efficiency in this system remained low (10.22%), and they also failed to achieve multiple phosphorescence emission with excitation wavelength control.

[0005] Therefore, there is an urgent need to develop a novel organic long afterglow material that combines high quantum yield, anti-Kasha type multiple phosphorescence emission, and excitation wavelength modulation characteristics. Summary of the Invention

[0006] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, one object of the present invention is to provide the application of the compound of formula (II).

[0007] The second objective of this invention is to provide an anti-Kasha organic long afterglow material.

[0008] The third objective of this invention is to provide a method for preparing this anti-Kasha organic long afterglow material.

[0009] The fourth objective of this invention is to provide a polymer film.

[0010] The fifth objective of this invention is to provide applications for anti-Kasha organic long afterglow materials or polymer films.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides the application of compounds of formula (II) in organic long afterglow materials: Formula (II).

[0012] In some embodiments of the present invention, the compound of formula (II) is prepared by a method comprising the following steps: Compound of formula (I) An oxidation reaction was carried out in the presence of an oxidant to obtain the compound of formula (II).

[0013] In some embodiments of the present invention, the compound of formula (II) is prepared, wherein the molar ratio of the compound of formula (I) to the oxidant is 1:(2-5).

[0014] In some preferred embodiments of the present invention, the compound of formula (II) is prepared, wherein the molar ratio of the compound of formula (I) to the oxidant is 1:(3-4).

[0015] In some embodiments of the present invention, the oxidant used to prepare the compound of formula (II) comprises a hydrogen peroxide solution with a concentration of 25wt%-35wt%.

[0016] In some embodiments of the present invention, the oxidation reaction for obtaining compound (II) further includes the use of a solvent selected from at least one of dichloromethane and trichloromethane.

[0017] In some embodiments of the present invention, the oxidation reaction for obtaining compound (II) is carried out at a temperature of 20-80°C for a time of 2-12 hours.

[0018] In some preferred embodiments of the present invention, the oxidation reaction for obtaining compound (II) is carried out at a temperature of 30-50°C for a time of 4-8 hours.

[0019] In some embodiments of the present invention, the preparation of compound (II) further includes a separation and purification operation after the oxidation reaction is completed, the separation and purification including extraction, drying and column chromatography performed sequentially.

[0020] In some embodiments of the present invention, the preparation of the compound of formula (II) involves extraction comprising separating the organic phase using a separatory funnel, wherein the extraction solvent is selected from at least one of dichloromethane and ethyl acetate.

[0021] In some embodiments of the present invention, the preparation of compound (II) involves drying using a drying agent selected from at least one of anhydrous sodium sulfate and anhydrous magnesium sulfate.

[0022] In some embodiments of the present invention, the column chromatography used to prepare the compound of formula (II) is a mixture of a polar solvent and a low polar solvent in a mass ratio of 1:(1-5).

[0023] In some embodiments of the present invention, the polar solvent used to prepare the compound of formula (II) is selected from at least one of dichloromethane, chloroform, ethyl acetate, and methanol.

[0024] In some embodiments of the present invention, the low-polarity solvent used to prepare the compound of formula (II) is selected from at least one of petroleum ether, n-hexane, and cyclohexane.

[0025] A second aspect of the present invention provides an anti-Kasha organic long afterglow material, comprising a host component and guest molecules doped in said host component; wherein, The main component includes melamine-formaldehyde resin; The guest molecule is the compound of formula (II) described in the first aspect of this invention.

[0026] In some embodiments of the present invention, the mass fraction of the guest molecule in the anti-Kasha organic long afterglow material is 0.01%-0.5%.

[0027] In some preferred embodiments of the present invention, the mass fraction of the guest molecule in the anti-Kasha organic long afterglow material is 0.05%-0.1%.

[0028] A third aspect of the present invention provides a method for preparing the anti-Kasha organic long afterglow material described in the second aspect of the present invention, comprising the following steps: S1. Mix melamine with formaldehyde aqueous solution, adjust the pH value to 7-11, heat to react, and obtain resin matrix; S2. The resin matrix is ​​mixed with the guest molecules, homogenized, and cured to obtain the anti-Kasha organic long afterglow material.

[0029] In some embodiments of the present invention, in step S1, the concentration of the formaldehyde aqueous solution is 30wt%-50wt%; the mass ratio of melamine to formaldehyde aqueous solution is (0.6-0.8):1.

[0030] In some preferred embodiments of the present invention, in step S1, the concentration of the formaldehyde aqueous solution is 35wt%-40wt%; the mass ratio of melamine to formaldehyde aqueous solution is (0.6-0.8):1.

[0031] In some embodiments of the present invention, step S1, adjusting the pH value to 7-11, includes using a pH adjuster.

[0032] In some embodiments of the present invention, in step S1, the pH adjuster is selected from at least one of organic amines, alkali metal hydroxides, and alkali metal carbonates.

[0033] In some preferred embodiments of the present invention, in step S1, the pH adjuster is selected from at least one of diethylamine, triethylamine, triethanolamine, sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0034] In some embodiments of the present invention, in step S1, the temperature of the heating reaction is 70-110°C and the time is 5-20 min.

[0035] In some preferred embodiments of the present invention, in step S1, the temperature of the heating reaction is 80-100°C and the time is 5-15 min.

[0036] In some embodiments of the present invention, in step S2, the homogenization treatment is carried out at a temperature of 40-60°C for a time of 10-40 minutes.

[0037] In some embodiments of the present invention, in step S2, the curing temperature is 50-120°C and the time is 1-5 hours.

[0038] In some preferred embodiments of the present invention, in step S2, the curing temperature is 80-100°C and the time is 1-2 hours.

[0039] A fourth aspect of the present invention provides a polymer film, wherein the raw materials for preparing the polymer film include the anti-Kasha organic long afterglow material described in the second aspect of the present invention.

[0040] In some embodiments of the present invention, the polymer film comprises a material prepared by hot pressing of the anti-Kasha organic long afterglow material.

[0041] In some embodiments of the present invention, the temperature of the hot pressing process is 130-190°C.

[0042] In some specific embodiments of the present invention, the temperature of the hot pressing process is 145-175°C.

[0043] In some embodiments of the present invention, the pressure of the hot pressing process is 15-20 MPa.

[0044] In some specific embodiments of the present invention, the pressure of the hot pressing process is 15-18 MPa.

[0045] In some embodiments of the present invention, the hot pressing process takes 5-15 minutes.

[0046] In some specific embodiments of the present invention, the hot pressing process takes 8-12 minutes.

[0047] The fifth aspect of the present invention provides the application of the anti-Kasha organic long afterglow material described in the second aspect of the present invention, or the polymer film described in the fourth aspect of the present invention, in the construction of information encryption devices or dynamic anti-counterfeiting systems.

[0048] Compared with the prior art, the beneficial effects of the present invention are: 1) The anti-Kasha organic long afterglow material provided by this invention precisely reconstructs the excited state energy levels of guest molecules through a sulfur oxidation strategy. Using melamine-formaldehyde resin as a rigid matrix, a pure organic long afterglow material system with both high quantum yield and anti-Kasha type multiple phosphorescence emission is successfully constructed. Compared with the unoxidized system, the singlet-triple state bandgap of the oxidized molecule is significantly reduced from 1.264 eV to 0.944 eV, significantly enhancing the intersystem crossing efficiency. At the optimal doping concentration, a phosphorescence quantum yield of up to 63.1% and a total quantum yield of 88.5% are achieved. In addition, the oxidized molecule forms a dense energy level layout of multiple triplet states. In the rigid matrix, the internal conversion from the high-energy triplet state to the lowest triplet state is effectively suppressed. For the first time in this type of system, anti-Kasha type multiple room-temperature phosphorescence emission with precise control over the excitation wavelength is achieved. 2) The preparation method of the anti-Kasha organic long afterglow material provided by this invention is simple and cost-controllable; 3) The anti-Kasha organic long afterglow material provided by this invention has extremely high application value in advanced anti-counterfeiting fields such as information encryption and dynamic anti-counterfeiting. Attached Figure Description

[0049] Figure 1 The 1H NMR spectrum of compound (I) is shown. Figure 2 The 1H NMR spectrum of compound (II) is shown. Figure 3 The steady-state emission spectra of the solid powders of compounds (I) and (II) are shown. Figure 4 The graph shows the luminescence decay curves of solid powders containing compounds of formula (I) and formula (II); Figure 5 The steady-state emission spectrum of the organic long afterglow material in Comparative Example 1; Figure 6 The graph shows the luminescence decay curve of the organic long afterglow material in Comparative Example 1. Figure 7 The steady-state emission spectrum of the anti-Kasha organic long afterglow material in Example 1; Figure 8 This is a graph showing the luminescence decay curve of the anti-Kasha organic long afterglow material in Example 1; Figure 9This is a normalized comparison of the delayed spectrum of the anti-Kasa organic long afterglow material at room temperature and the delayed spectrum of the small molecule of compound (II) at different concentrations in a 77K tetrahydrofuran solution in Example 1. Figure 10 The following are the delayed spectra of the anti-Kasha organic long afterglow material in Example 1 at different excitation wavelengths; Figure 11 This is a two-dimensional excitation-emission mapping diagram of the anti-Kasha organic long afterglow material in Example 1; Figure 12 The normalized comparison of the delayed spectrum of the organic long afterglow material at room temperature and the delayed spectrum of the small molecule of compound (Ⅰ) at different concentrations in tetrahydrofuran solution at 77K is shown in Comparative Example 1. Figure 13 The following are the delayed spectra of the organic long afterglow material in Comparative Example 1 at different excitation wavelengths; Figure 14 This is a two-dimensional excitation-emission mapping diagram of the organic long afterglow material in Comparative Example 1; Figure 15 The delayed emission spectra of the anti-Kasha organic long afterglow material in Example 1 under 300nm high-energy excitation at different temperatures are shown. Figure 16 The graph shows the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 490nm emission peak under 300nm high-energy excitation as a function of temperature. Figure 17 The graph shows the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 590nm emission peak under 300nm high-energy excitation as a function of temperature. Figure 18 The delayed emission spectra of the anti-Kasha organic long afterglow material in Example 1 at different temperatures under 410 nm low-energy excitation are shown. Figure 19 The graph shows the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 490nm emission peak under 410nm low-energy excitation as a function of temperature. Figure 20 The graph shows the lifetime of the anti-Kasa organic long afterglow material in Example 1 as a function of temperature at the 585nm emission peak under 410nm low-energy excitation. Figure 21 The images show the application of organic long afterglow materials in anti-counterfeiting and information encryption in Example 1 and Comparative Example 1. Detailed Implementation

[0050] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0051] The structures of compounds of formula (I) used in the following examples and comparative examples are as follows: The Chinese name is 5H-benzo(A)(1)benzothiophene(3,2-C)carbazole, CAS number is 1442458-61-8, purchased from Anaiji Chemical, catalog number E02183123, purity ≥98%.

[0052] The structure of compound (II) is as follows It is prepared from the compound of formula (I) as a raw material, and the steps are as follows: 1) Dissolve compound (SNH) of formula (Ⅰ) (0.50 g, 1.55 mmol) in 30 mL of dichloromethane, add 30 wt% hydrogen peroxide solution (0.526 g, 4.64 mmol), stir at 40 °C for 6 h, monitor the reaction progress by thin layer chromatography (TLC) until the starting material spot completely disappears; 2) After the reaction is complete, the reaction solution is transferred to a separatory funnel, washed with 30 mL of distilled water, and the organic phase is collected by separation. The aqueous phase is extracted twice with 20 mL of dichloromethane. The organic phases are combined and dried with anhydrous sodium sulfate for 30 min. The solution is filtered and the solvent is removed by rotary evaporation under reduced pressure at 40 °C to obtain the crude product. 3) The crude product was purified by silica gel column chromatography using a mixed solution of dichloromethane / petroleum ether (1:2, v / v) as the eluent. The target product fraction was collected and the solvent was removed by rotary evaporation under reduced pressure at 40°C. The resulting solid was recrystallized in a mixed solvent of dichloromethane and n-hexane to obtain 0.42 g of white solid powder, which is compound (II) with a yield of 78.5%.

[0053] The synthetic route for compound (II) is shown below:

[0054] Figure 1 The 1H NMR spectrum of compound (I) is shown. Figure 2 The 1H NMR spectrum of compound (II) is given by... Figure 1 and Figure 2 It can be seen that, compared with the spectrum of compound (I), the characteristic hydrogen of compound (II) exhibits a characteristic chemical shift due to the electronic effect of sulfur atom oxidation, and the peak shape and integral ratio are consistent with the theoretical structure of compound (II), so it can be used as a raw material for the preparation of organic long afterglow materials.

[0055] Example 1 This embodiment prepares an anti-Kasha organic long afterglow material, and the steps are as follows: S11. Add 30g of melamine powder to 43g of 37wt% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, heat at 90℃ for 10min to obtain resin matrix; S21. Take 1g of resin matrix and 0.5mg of solid powder of compound (II) into a 5mL transparent sample tube, sonicate at 50℃ until clear and transparent, coat it on a quartz plate, heat at 150℃ for 6h to obtain anti-Kasha organic long afterglow material, wherein the doping amount of compound (II) is 0.05wt%.

[0056] The above-mentioned anti-Kasha organic long afterglow material was hot-pressed at 160°C and 18MPa for 10 min to obtain a polymer film.

[0057] Comparative Example 1 This comparative example prepares an organic long afterglow material, and the steps are as follows: S11. Add 30g of melamine powder to 43g of 37wt% formaldehyde aqueous solution, then add triethanolamine to adjust the pH of the solution to 8-9, heat at 90℃ for 10min to obtain resin matrix; S21. Take 1g of resin matrix and 1mg of solid powder of compound (I) and place them in a 5mL transparent sample tube. Sonicate at 50℃ until clear and transparent. Coat it on a quartz plate and heat at 150℃ for 6h to obtain anti-Kasha organic long afterglow material, wherein the doping amount of compound (I) is 0.1wt%.

[0058] The above-mentioned organic long afterglow material was hot-pressed at 160°C and 18MPa for 10 min to obtain a polymer film.

[0059] Performance testing The optical properties of compounds of formulas (I) and (II), as well as the organic long-afterglow materials prepared in Example 1 and Comparative Example 1, were tested. All tests were performed on an Edinburgh FLS980 steady-state and transient fluorescence spectrometer with an integrating sphere and an OceanOptics QE65 Pro CCD fiber spectrometer. The afterglow emission performance of two guest molecules with different structures in a melamine-formaldehyde resin matrix was investigated, including steady-state and delayed emission spectra, afterglow lifetime, quantum yield, and temperature-dependent spectral behavior, aiming to reveal the mechanism by which molecular structure regulation affects luminescence mode and efficiency. Figure 3 The steady-state emission spectra of solid powders containing compounds of formula (I) and formula (II) are shown. Figure 4The graphs show the luminescence decay curves of solid powders containing compounds of formulas (I) and (II), derived from... Figure 3 and Figure 4 It can be seen that neither of the two compound solid powders exhibited obvious long-lifetime phosphorescence emission, with their luminescence lifetimes both being less than 6ms. This indicates that it is difficult for simple molecular aggregates to achieve efficient phosphorescence emission, highlighting the important role of the rigid polymer matrix (melamine-formaldehyde resin) in suppressing nonradiative transitions and stabilizing triplet excitons.

[0060] Figure 5 The steady-state emission spectrum of the organic long afterglow material in Comparative Example 1 is shown. Figure 6 This is a graph showing the luminescence decay curve of the organic long-afterglow material in Comparative Example 1. Figure 7 This is the steady-state emission spectrum of the anti-Kasha organic long afterglow material in Example 1. Figure 8 This is the luminescence decay curve of the anti-Kasha organic long afterglow material in Example 1, from... Figures 5-8 It can be seen that the organic long afterglow material in Comparative Example 1 exhibits the strongest delayed emission signal at 506 nm, with a phosphorescence lifetime as high as 0.985 s. The anti-casa organic long afterglow material in Example 1 exhibits the strongest delayed emission signal at 490 nm, with a phosphorescence lifetime of 0.726 s. This indicates that the sulfur oxidation strategy not only reconstructs the energy level structure of the guest molecules, but also changes the luminescence mode after it is combined with the melamine-formaldehyde resin matrix.

[0061] Figure 9 This is a normalized comparison of the delayed spectrum of the anti-casa organic long afterglow material in Example 1 at room temperature and the delayed spectrum of the small molecule of compound (II) at different concentrations in tetrahydrofuran solution at 77K. Figure 9 It can be seen that the delayed spectra of the small molecule of compound (II) at different concentrations in 77K tetrahydrofuran solution are highly overlapping, showing double peaks at 500nm and 536nm. In contrast, the anti-Kasha organic long afterglow material in Example 1 only shows a main peak at 490nm and a weak shoulder peak at 550nm, suggesting that the population of the multiple triplet emission channels in the anti-Kasha organic long afterglow material has changed.

[0062] Figure 10 The images show the delayed spectra of the anti-Kasha organic long afterglow material in Example 1 at different excitation wavelengths. Figure 11 This is the excitation-emission two-dimensional mapping of the anti-Kasha organic long afterglow material in Example 1, by... Figure 10 and Figure 11 It can be seen that the relative intensity of the shoulder peak at 550nm is significantly enhanced and tends to dominate under high-energy excitation, while the main peak at 490nm is absolutely dominant under low-energy excitation, proving that the excitation wavelength can selectively control the population of different triplet emission channels.

[0063] To quantify the excitation wavelength modulation characteristics of the anti-Kasha organic long afterglow material in Example 1, the relative intensity ratio (Ig) of the emission peaks at 490 nm and 550 nm under different excitation wavelengths was systematically measured. 490 / I 550 The results show that this ratio exhibits a significant excitation wavelength dependence: under low-energy excitation of 410 nm, I 490 / I 550 The ratio is as high as 11.29, indicating that the emission peak at 490 nm is absolutely dominant. As the excitation wavelength blue shifts, the ratio gradually decreases. Under excitation at 390 nm, 365 nm, 330 nm, and 300 nm, I... 490 / I 550 The values ​​were 10.807, 3.148, 1.829, and 1.0937, respectively. When the excitation wavelength was 300 nm, the ratio approached 1, indicating that the emission peak intensities at 490 nm and 550 nm were comparable, and the system exhibited a bimodal emission characteristic. This quantitative data directly confirmed that the excitation wavelength can selectively control the population of different triplet emission channels. Low-energy excitation preferentially populations the high-energy triplet state (T2 / T3) to produce 490 nm emission, while high-energy excitation promotes exciton relaxation to the low-energy triplet state (T1) and enhances 550 nm emission. This provides a quantitative basis for the excited-state dynamics mechanism of anti-Kasha type multiple phosphorescence in the system.

[0064] Figure 12 The normalized comparison diagram shows the delayed spectrum of the organic long afterglow material at room temperature and the delayed spectrum of the small molecule of compound (I) at different concentrations in tetrahydrofuran solution at 77K. The delayed spectrum of the organic long afterglow material at room temperature and the delayed spectrum of the small molecule of compound (I) at different concentrations in tetrahydrofuran solution at 77K highly overlap, both showing double peaks at around 500nm and 530nm, indicating that its phosphorescence emission originates from the intrinsic single-molecule state behavior of the molecule.

[0065] Figure 13 The images show the delayed spectra of the organic long afterglow material in Comparative Example 1 at different excitation wavelengths. Figure 14 The excitation-emission two-dimensional mapping of the organic long afterglow material in Comparative Example 1 is shown by... Figure 13 and Figure 14 It can be seen that the emission peak shape of the organic long afterglow material in Comparative Example 1 does not change with the excitation wavelength and does not have the characteristic of excitation wavelength modulation.

[0066] Figure 15 The images show the delayed emission spectra of the anti-Kasha organic long afterglow material in Example 1 under 300 nm high-energy excitation at different temperatures. Figure 15 It can be seen that as the temperature increases, the overall delay intensity gradually decreases, and the intensity of the main peak at 490nm decreases particularly significantly, gradually decreasing to the same level as the shoulder peak intensity at 590nm.

[0067] Figure 16 This is a graph showing the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 490nm emission peak under 300nm high-energy excitation as a function of temperature. Figure 17 This is a graph showing the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 590nm emission peak under 300nm high-energy excitation as a function of temperature. Figure 16 and Figure 17 It can be seen that below 273K, the lifetime at 490nm is always greater than that at 590nm, while above 273K, the lifetimes at the two locations tend to be close, indicating that heating promotes the internal conversion relaxation from the high-energy triplet state to T1.

[0068] Figure 18 The image shows the delayed emission spectra of the anti-Kasha organic long afterglow material in Example 1 under low-energy excitation at 410 nm at different temperatures. Throughout the temperature range, the delayed spectrum is dominated by the emission peak at 490 nm, while the shoulder peak at 585 nm is only a weak shoulder peak. The intensity and peak shape are less affected by temperature.

[0069] Figure 19 This is a graph showing the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 490nm emission peak under low-energy excitation of 410nm as a function of temperature. Figure 20 This is a graph showing the lifetime of the anti-Kasha organic long afterglow material in Example 1 at the 585nm emission peak under 410nm low-energy excitation as a function of temperature. Figure 19 and Figure 20 It can be seen that throughout the entire temperature range, the lifetime at 490 nm is always greater than that at 585 nm, and the lifetime changes at the two locations are relatively gradual, indicating that under low-energy excitation, the exciton population is concentrated in the high-energy triplet state and is less affected by temperature.

[0070] To systematically reveal the excited-state dynamics of multiple phosphorescent channels in the anti-Kasha organic long-afterglow material of Example 1, the lifetime of each emission peak under different excitation conditions was measured with temperature (78K-380K). Under 300nm high-energy excitation, the lifetimes of both the 490nm and 590nm emission peaks gradually decreased with increasing temperature, and the difference in lifetimes between the two showed a significant temperature dependence: below 273K, the lifetime at 490nm (80K: 0.864s→273K: 0.486s) was always greater than that at 590nm (80K: 0.742s→273K: 0.483s); when the temperature rose above 273K, the lifetimes at both points rapidly decayed and tended to approach each other (0.104s and 0.100s, respectively, at 380K). This trend quantitatively confirmed that heating promoted the internal conversion relaxation from the high-energy triplet state to T1, leading to a convergence of the dynamic behaviors of the two emission channels. Under low-energy excitation of 410 nm, the emission lifetime at 490 nm remained stable across the entire temperature range (80 K: 1.034 s → 298 K: 1.013 s → 380 K: 1.009 s), consistently exceeding that at 585 nm (80 K: 0.571 s → 298 K: 0.563 s → 380 K: 0.56 s), with the latter showing a relatively gradual change. This indicates that under low-energy excitation, the exciton population is concentrated in the high-energy triplet state (T2 / T3), and is less affected by temperature. The attribution of the 490 nm and 585 nm emissions to different triplet energy levels is further confirmed. These quantitative data provide crucial experimental evidence for understanding the excited-state dynamics mechanism of anti-Kasha type multiple phosphorescence in the system.

[0071] Table 1. Photophysical property data of organic long afterglow materials in Example 1 and Comparative Example 1

[0072] Table 1 shows the photophysical properties of the organic long-afterglow materials in Example 1 and Comparative Example 1. As can be seen from Table 1, the optimal doping amount of compound (II) as a guest molecule in the anti-Kassa organic long-afterglow material is 0.05 wt%, with a total quantum yield of 88.5% and an afterglow quantum yield of 63.1%, which is higher than the total quantum yield (55.84%) and afterglow quantum yield (45.12%) of compound (I) at the optimal doping concentration (0.1 wt%). The phosphorescence lifetime of the organic long-afterglow material in Example 1 is lower than that in Comparative Example 1, which provides a basis for the performance difference in subsequent time-based anti-counterfeiting applications.

[0073] Figure 21 These are illustrations demonstrating the application of organic long afterglow materials in anti-counterfeiting and information encryption in Example 1 and Comparative Example 1. Figure 21It can be seen that after the polymer films in Example 1 and Comparative Example 1 are made into specific patterns, they both exhibit bright fluorescence under 365nm ultraviolet light excitation. When the excitation light source is turned off, both emit green afterglow. By comparing the afterglow decay process, it can be found that the afterglow duration of the polymer film in Comparative Example 1 is significantly longer than that of the polymer film in Example 1. The former can last for several seconds or more, while the latter has a relatively short afterglow lifetime. This difference is due to the different triplet energy level structure and excited state dynamic behavior of the two materials. By utilizing the significant difference in afterglow lifetime between the two, a dynamic anti-counterfeiting system or advanced information encryption device based on time dimension resolution can be constructed.

[0074] In summary, the sulfur-oxidized anti-Kasha organic long-afterglow material of this invention exhibits higher phosphorescence quantum yield (>60%) and total quantum yield (>85%), and demonstrates wavelength-dependent anti-Kasha type multiple phosphorescence emission. In existing technologies, He et al. reported a dual-phosphorescent system with a quantum yield of only 7.2%, dependent on heavy atoms and lacking excitation wavelength modulation; Xie et al. achieved a phosphorescence efficiency of 29.79% in the thiophene derivative@PVA system, but did not achieve anti-Kasha type emission; Zhang et al. achieved wavelength-modulated anti-Kasha fluorescence, but it was a fluorescent system, not phosphorescent. In contrast, this invention reduces the singlet-triplet bandgap (ΔEST) from 1.264 eV to 0.944 eV through a sulfur oxidation strategy, achieving a high phosphorescence quantum yield of 63.1% and a total quantum yield of 88.5% at the optimal doping ratio, far exceeding existing levels. Simultaneously, it achieves wavelength-modulated anti-Kasha type multiple emission in a phosphorescent system for the first time: I4 at low energy excitation (410 nm)… 90 / I 550 The ratio reached 11.29, and the ratio decreased to 1.09 under high-energy excitation (300nm). The 590nm shoulder peak was significantly enhanced. The variable-temperature lifetime data further revealed the dynamic differences between the two emission channels, confirming the excited state origin of multiple triplet emission. That is, the technical effects achieved by this invention in terms of quantum yield, excitation wavelength control and multiple emission tunability are significantly better than the existing technology.

Claims

1. Application of compound (II) in organic long afterglow materials: Formula (II).

2. The application according to claim 1, characterized in that, The compound of formula (II) is prepared by a method comprising the following steps: Compound of formula (I) An oxidation reaction was carried out in the presence of an oxidant to obtain the compound of formula (II).

3. The application according to claim 2, characterized in that, The compound of formula (II) is obtained, wherein the molar ratio of the compound of formula (I) to the oxidant is 1:(2-5); And / or, the oxidation reaction is carried out at a temperature of 20-80°C for a time of 2-12 hours.

4. An anti-Kasha organic long afterglow material, characterized in that, It includes a host component and guest molecules doped in the host component; wherein, The main component includes melamine-formaldehyde resin; The guest molecule is the compound of formula (II) as described in any one of claims 1-3.

5. The anti-Kasha organic long afterglow material according to claim 4, characterized in that, In the aforementioned anti-Kasha organic long afterglow material, the mass fraction of the guest molecule is 0.01%-0.5%.

6. The method for preparing the anti-Kasha organic long afterglow material according to claim 4 or 5, characterized in that, Includes the following steps: S1. Mix melamine with formaldehyde aqueous solution, adjust the pH value to 7-11, heat to react, and obtain resin matrix; S2. The resin matrix is ​​mixed with the guest molecules, homogenized, and cured to obtain the anti-Kasha organic long afterglow material.

7. The method for preparing the anti-Kasha organic long afterglow material according to claim 6, characterized in that, In step S1, the concentration of the formaldehyde aqueous solution is 30wt%-50wt%; the mass ratio of melamine to formaldehyde aqueous solution is (0.6-0.8):

1. And / or, the heating reaction is carried out at a temperature of 70-110°C for a time of 5-20 min.

8. The preparation method according to claim 6, characterized in that, In step S2, the homogenization process is carried out at a temperature of 40-60°C for 10-40 minutes. And / or, the curing temperature is 50-120℃ and the time is 1-5h.

9. A polymer film, characterized in that, The raw materials for preparing the polymer film include the anti-casa organic long afterglow material as described in claim 4 or 5.

10. The anti-Kasha organic long afterglow material of claim 4 or 5, or the polymer film of claim 9, in the construction of information encryption devices or dynamic anti-counterfeiting systems.

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