Aqueous-phase bi-component phosphorescent silicon dioxide nanoparticles as well as preparation method and application thereof

Abstract

The invention provides an aqueous-phase bi-component phosphorescent silicon dioxide nanoparticle as well as a preparation method and application thereof. The phosphorescent silicon dioxide nanoparticles take a surfactant as a shell and take an assembly formed by hydrolytic condensation of phosphorescent molecules, blocking agent molecules and silicon precursor molecules as an inner core, and the blocking agent molecules are utilized in the inner core to separate the phosphorescent molecules so as to prevent the phosphorescent molecules from gathering and self-quenching. Through the special structural design, phosphorescent molecules with higher concentration can be introduced into the material without aggregation self-quenching, the obtained phosphorescent silicon dioxide nanoparticles have high phosphorescent brightness and phosphorescent quantum efficiency, the highest phosphorescent brightness reaches 98578M <-1 > cm <-1 >, the highest phosphorescent quantum efficiency phi is 18.16%, and the phosphorescent lifetime is about 6ms. The phosphorescent silicon dioxide nanoparticles are also used for information display, information encryption and preparation of flexible luminescent materials, and show excellent phosphorescent emission performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic nanomaterials and their preparation, and specifically includes an aqueous two-component phosphorescent silica nanoparticle, a preparation method thereof, and an application thereof. Background Art

[0002] Due to the advantages of high exciton utilization rate, long excited state lifetime, low cost, and low toxicity, organic room temperature phosphorescent nanomaterials have been widely used in anti-counterfeiting, optoelectronics, sensing, and other aspects. Among them, phosphorescence brightness is one of the important parameters determining the sensitivity in applications. Specifically, phosphorescence brightness is used to quantify the actual luminescence. That is, when a large number of phosphorescent molecules are added to nanoparticles (NPs), the phosphorescence signal generated by the nanoparticles (NPs) is the product of the number of phosphorescent groups, molar absorption coefficient ε, and phosphorescence quantum yield Φ contained in a single NP, that is, Bp = nεΦ. Therefore, to obtain high-brightness phosphorescent nanomaterials, design and improvement can be carried out from two aspects: improving the phosphorescence quantum efficiency and increasing the number of phosphorescent groups in a single NP. First, in terms of improving the phosphorescence quantum efficiency, the current strategy is often to reduce the doping ratio of phosphorescent molecules to avoid aggregation self-quenching. Therefore, the studied doping ratios are mostly less than 1%. And according to the existing reports, it has been analyzed in detail that when the doping ratio in this research system is 0.05%, the phosphorescence quantum efficiency is the largest, while when the doping ratio is 1%, severe aggregation self-quenching leads to a sharp drop in the phosphorescence quantum efficiency. Second, in terms of increasing the number of phosphorescent groups in a single NP, due to severe intermolecular quenching of phosphorescent molecules in a limited space, increasing the number of phosphorescent groups n in highly doped nanoparticles will endanger the phosphorescence quantum yield. To reduce the aggregation quenching problem of phosphorescent molecules, the currently commonly used solution is to directly introduce large steric hindrance groups into the compound structure of phosphorescent molecules to increase the intermolecular steric hindrance of phosphorescent molecules, thereby preventing aggregation. However, this approach is relatively cumbersome. When the chromophore needs to be changed, new phosphorescent molecules with large steric hindrance groups need to be synthesized again to meet the requirements, which is time-consuming and laborious. Coupled with the spin-forbidden characteristics of the organic room temperature phosphorescence triplet excited state and unfavorable vibrational dissipation, as well as the quenching of water and oxygen, achieving efficient aqueous organic room temperature phosphorescence has always been a research difficulty. Therefore, it is challenging to achieve high-brightness aqueous organic room temperature phosphorescence by simultaneously increasing the doping dye concentration and improving the phosphorescence quantum efficiency. Summary of the Invention

[0003] Aiming at the above problems existing in the prior art, the first object of the present invention is to provide an aqueous two-component phosphorescent silica nanoparticle. The concentration of phosphorescent molecules incorporated in the phosphorescent silica nanoparticle is higher, and it has high phosphorescence brightness and phosphorescence quantum efficiency, and the highest phosphorescence brightness reaches 98578 M -1 cm -1, the highest phosphorescence quantum efficiency Φ is 18.16%, and the phosphorescence lifetime is about 6 ms.

[0004] The second object of the present invention is to provide a method for preparing the aqueous two-component phosphorescent silica nanoparticles as described above.

[0005] The third object of the present invention is to provide an application of the aqueous two-component phosphorescent silica nanoparticles as described above in information display, information encryption, and preparation of flexible luminescent materials.

[0006] To achieve the above first object, the technical solutions adopted by the present invention include:

[0007] The present invention discloses an aqueous two-component phosphorescent silica nanoparticle. Refer to Figure 1 , the phosphorescent silica nanoparticle is a nanoparticle with a surfactant as the outer shell and an assembly formed by hydrolysis and condensation of phosphorescent molecules, blocker molecules, and silicon precursor molecules as the inner core. In the inner core, the phosphorescent molecules are separated by the blocker molecules to prevent aggregation and self-quenching.

[0008] Among them, the phosphorescent molecule is selected from one of the following general formula structures:

[0009]

[0010] R is selected from one of the following structures:

[0011]

[0012] X is selected from any one of Cl, Br, and I;

[0013] R1 is selected from any one of H, CH3, and C2H5;

[0014] The blocker molecule is selected from the compounds with the following structures:

[0015]

[0016] In the present invention, the two components in the aqueous two-component phosphorescent silica nanoparticles refer to the phosphorescent molecules and the blocker molecules connected by covalent bonds. Experiments have found that since both the blocker molecules and the phosphorescent molecules contain siloxyethyl groups, this group can rapidly undergo hydrolysis and condensation with the silicon precursor molecules under acidic conditions, and stimulate the formation of Si-O-Si chains. Then, under the hydrophilic-hydrophobic interaction of the surfactant, finally, the phosphorescent molecules and the blocker molecules are co-doped into the silica nanoparticles, enabling the silica nanoparticles to achieve the emission of aqueous organic room temperature phosphorescence in an argon atmosphere. More importantly, the phosphorescent molecules and the blocker molecules are confined inside relatively small silica nanoparticles. In this restricted microenvironment, it is conducive to the positioning of the blocker molecules and the phosphorescent molecules. The blocker molecules can isolate the phosphorescent molecules for self-assembly to reduce the aggregation self-quenching of the phosphorescent molecules and inhibit the non-radiative inactivation of the organic room temperature phosphorescent molecules. In this way, a higher concentration of phosphorescent molecules can be introduced to obtain higher brightness phosphorescent emission, while maintaining a relatively high phosphorescence lifetime. When it is necessary to change the chromophore to cause phosphorescence changes, directly replacing the phosphorescent molecules with the target chromophore is sufficient, without introducing large steric hindrance groups in the compound structure of the new phosphorescent molecules to eliminate the aggregation self-quenching of the phosphorescent molecules, and the operation is more convenient.

[0017] Further, the phosphorescent molecule is selected from one of the following structures:

[0018]

[0019] Further, the silicon precursor molecule is selected from tetraethoxysilane, and the surfactant is selected from poloxamer F127.

[0020] Further, the particle size of the phosphorescent silica nanoparticles is 10.2 ± 0.7 nm.

[0021] To achieve the second objective above, the technical solution adopted by the present invention includes:

[0022] The present invention discloses a preparation method of the phosphorescent silica nanoparticles as described above, including the following steps:

[0023] Add the phosphorescent molecules, the blocker molecules and the surfactant into ultra-dry dichloromethane. After mixing evenly, evaporate the organic solvent. Add solid NaCl and glacial acetic acid to redissolve the above materials, and then add the silicon precursor molecules. React at 20 - 30 °C for 2.5 - 3.5 h. After the reaction is completed, terminate the reaction with trimethylchlorosilane. After stirring at a constant temperature for 24 - 48 h, add deionized water for dilution, and then dialyze to obtain the product.

[0024] The preparation method of the present invention is based on the synthesis principle of the template micelle method. Utilizing the hydrophilic-hydrophobic interaction of poloxamer F127, it is used as a self-assembly template to restrict the morphology of silica nanoparticles. Meanwhile, the size of silica nanoparticles is restricted by the condensation process of blocker molecules, phosphorescent molecules and the precursor TEOS.

[0025] The phosphorescent silica nanoparticles provided by the present invention are dispersed in the aqueous phase, that is, the silica nanoparticle stock solution, and are also in a solution state during storage and use. After the nanoparticles are formed, the colloidal suspension is dialyzed to remove surfactants, silica oligomers and uncaught dyes, and finally an aqueous two-component silica nanoparticle, that is, the silica nanoparticle stock solution, is obtained.

[0026] Further, the concentration of the glacial acetic acid is 1M.

[0027] Within a certain range, as the doping ratio of the blocker molecules increases, under argon conditions, the phosphorescent emission of the obtained phosphorescent silica nanoparticles will be enhanced, the phosphorescent quantum yield will be increased, and the phosphorescent brightness will be enhanced. This is because the gradually increasing content of the blocker molecules effectively isolates the phosphorescent molecules in the silica nanoparticles, reduces the interaction between the phosphorescent molecules, prevents the aggregation quenching of the phosphorescent molecules, and inhibits the non-radiative deactivation of the organic room-temperature phosphorescent molecules. In a specific embodiment, the molar ratio of the phosphorescent molecules to the blocker molecules is 1:1 - 1:7; exemplarily, the molar ratio of the phosphorescent molecules to the blocker molecules can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, etc.

[0028] The molar ratio of the phosphorescent molecules to the silicon precursor molecules is 0.0001 - 0.008:1, preferably 0.01:1.

[0029] Further, the mass ratio of the surfactant to the silicon precursor molecules is 100:169.

[0030] Further, the purpose of dialysis is to remove unreacted surfactants, silica oligomers and uncaught phosphorescent molecules. The cut-off molecular weight of the dialysis bag used during dialysis is 8000 - 14000.

[0031] To achieve the above third objective, the technical solution adopted by the present invention includes:

[0032] The present invention discloses an application of the phosphorescent nanoparticles as described above in information display, information encryption and the preparation of flexible luminescent materials.

[0033] Further, the application specifically uses the aqueous two-component phosphorescent silica nanoparticles as a chromogenic agent for information display and information encryption; or the aqueous two-component phosphorescent silica nanoparticles are doped into a polymer to prepare a polymer film with phosphorescent emission.

[0034] Advantages of the present invention:

[0035] The present invention provides an aqueous two-component phosphorescent silica nanoparticle. The phosphorescent silica nanoparticle is a nanoparticle with a surfactant as the outer shell and an assembly formed by hydrolysis and condensation of phosphorescent molecules, barrier molecules, and silicon precursor molecules as the inner core. In the inner core, the phosphorescent molecules are separated by the barrier molecules to prevent aggregation and self-quenching. Through this special structural design, a higher concentration of phosphorescent molecules can be introduced into the material without aggregation and self-quenching. The obtained phosphorescent silica nanoparticles have high phosphorescent brightness and phosphorescent quantum efficiency. The highest phosphorescent brightness reaches 98578 M -1 cm -1 , the highest phosphorescent quantum efficiency Φ is 18.16%, and the phosphorescent lifetime is about 6 ms.

[0036] The present invention also provides an application of the aqueous two-component phosphorescent silica nanoparticle in information display, information encryption, and preparation of flexible luminescent materials. In specific applications, the aqueous two-component phosphorescent silica nanoparticles can be used as a chromogenic agent for information display and information encryption, showing characteristic phosphorescent emission; or the aqueous two-component phosphorescent silica nanoparticles are doped into a polymer to prepare a polymer film with phosphorescent emission. Brief Description of the Drawings

[0037] The following further describes in detail the specific embodiments of the present invention with reference to the drawings.

[0038] Figure 1 Shows a schematic structural diagram of the aqueous two-component phosphorescent silica nanoparticle provided by the present invention.

[0039] Figure 2 Shows the ultraviolet-visible absorption spectrum of the phosphorescent molecule P1 prepared in Example 1 in an organic solvent under air conditions.

[0040] Figure 3 Shows the fluorescence emission spectrum and delayed emission spectrum of the phosphorescent molecule P1 prepared in Example 1 in an organic solvent under air conditions at 77K.

[0041] Figure 4 Shows P1 prepared in Example 1 1％ S1 y％ @NPs transmission electron microscope.

[0042] Figure 5Shows P1 prepared in Example 1 1％ @UV-visible absorption spectra in NPs.

[0043] Figure 6 Shows P1 prepared in Example 1 1％ @Fluorescence spectra before and after degassing and delayed spectra after deoxygenation in NPs.

[0044] Figure 7 Shows S1 prepared in Example 1 5％ @UV-visible absorption spectra in NPs.

[0045] Figure 8 Shows S1 prepared in Example 1 5％ @Phosphorescence spectra after degassing in NPs.

[0046] Figure 9 Shows P1 prepared in Example 1 1％ S1 y％ @UV-visible absorption spectra of NPs.

[0047] Figure 10 Shows P1 prepared in Example 1 1％ S1 y％ @Fluorescence spectra of NPs in argon.

[0048] Figure 11 Shows P1 prepared in Example 1 1％ S1 y％ @Phosphorescence spectra of NPs in argon.

[0049] Figure 12 Shows P1 prepared in Example 1 1％ S1 y％ @Phosphorescence lifetime spectra of NPs in argon.

[0050] Figure 13 Shows P1 prepared in Example 1 1％ S1 y％ @Phosphorescence quantum efficiency of NPs in argon.

[0051] Figure 14 Shows the relationship diagram between the doping ratio of phosphorescent molecule-doped silica nanoparticles and the number of phosphorescent molecules contained in a single silica nanoparticle.

[0052] Figure 15 Shows P1 prepared in Example 1 1％ S1 y％ @Phosphorescence brightness of NPs in argon.

[0053] Figure 16 Shows P1 prepared in Example 1, Comparative Example 1 and Comparative Example 2 1％ S1y％ @NPs, P1 1％ S2 y％ @NPs and P1 1％ S3 y％ Phosphorescence brightness of @NPs in argon gas.

[0054] Figure 17 Shows P1 prepared in Example 1, Comparative Example 1 and Comparative Example 2 1％ S1 7％ @NPs, P1 1％ S2 7％ @NPs and P1 1％ S3 7％ Phosphorescence lifetime spectrum of @NPs in argon gas.

[0055] Figure 18 Shows P2 prepared in Example 2 and Example 3 1％ @NPs, P3 1％ @NPs, P2 1％ S1 7％ @NPs, P3 1％ S1 7％ Phosphorescence brightness of @NPs in argon gas.

[0056] Figure 19 Shows P1 prepared using Example 1 respectively 1％ @NPs and P1 1％ S1 7％ @NPs is used as a chromogenic agent for information display.

[0057] Figure 20 Shows P1 prepared using water and Example 1 respectively 1％ S1 7％ Schematic diagram of @NPs used as a chromogenic agent for information encryption.

[0058] Figure 21 Shows the doped P1 in Example 5 respectively 1％ @NPs, P2 1％ @NPs, P3 1％ @NPs, P1 1％ S1 7％ @NPs, P2 1％ S1 7％ @NPs, P3 1％ S1 7％ Schematic diagram of the polymer film of @NPs.

[0059] Figure 22 Shows the doped P1 in Example 5 respectively 1％ @NPs, P1 1％ S1 7％Schematic diagram of making a polymer film of @NPs into a tree. Detailed implementation mode

[0060] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with preferred embodiments and drawings. It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work belong to the scope of protection of the present invention.

[0061] Unless otherwise specified, the raw materials used in the present invention can be obtained through commercial purchase. Any range recorded in the present invention includes the end values and any numerical value between the end values, as well as any sub-range composed of any numerical value between the end values or the end values.

[0062] Unless otherwise specified, the relevant tests in terms of phosphorescence in the present invention are all carried out under degassing conditions. Degassing refers to removing oxygen. For example, argon can be introduced to remove oxygen in the system.

[0063] Example 1

[0064] (1) Synthesis of phosphorescent molecule P1:

[0065]

[0066] Dissolve 6-bromo-2-naphthoic acid (143.1 mg, 0.57 mmol), 3-aminopropyltriethoxysilane (270 μL, 1.15 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCl) (220 mg, 1.15 mmol), hydroxybenzotriazole monohydrate (HOBt) (155 mg, 1.15 mmol) and triethylamine (159 μL, 1.15 mmol) in 60 mL of ultradry dichloromethane and stir at room temperature overnight. Then evaporate the ultradry dichloromethane completely under reduced pressure, and purify the obtained residue by column chromatography to obtain a white solid product P1. 1 H NMR (400 MHz, DMSO-d6) δ 8.64 (t, J = 5.6 Hz, 1H), 8.43 (s, 1H), 8.25 (s, 1H), 7.97 (d, J = 12.3 Hz, 3H), 7.69 (d, J = 8.8 Hz, 1H), 3.74 (q, J = 7.0 Hz, 6H), 3.26 (t, J = 6.7 Hz, 2H), 1.60 (p, J = 7.5 Hz, 2H), 1.13 (t, J = 7.0 Hz, 9H), 0.64 - 0.58 (m, 2H); 13CNMR(101MHz, DMSO-d6) δ 165.82, 135.12, 132.62, 130.99, 130.70, 129.68, 129.54, 127.33, 127.06, 125.34, 120.78, 57.70, 42.14, 22.71, 18.20, 7.47. HRMS(ESI) m / z: [M+K] + Calculated for, [C 20 H 28 NO4SiKBr] + : 492.0971; Found: 492.0609.

[0067] The phosphorescent molecule P1 contains units, which are easy to synthesize and chemically modify, and are commonly used as organic synthesis intermediates for dyes and pigments; among them, the heavy atom Br can promote the intersystem crossing from the singlet state to the triplet state, enhance the phosphorescence emission, and also replace the traditional room-temperature phosphorescent molecules containing heavy atoms such as metals, with biological safety.

[0068] (2) Synthesis of the barrier molecule S1:

[0069]

[0070] ① Dissolve α,α'-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene (2 g, 5.8 mmol) in 200 mL of THF, then add triethylamine (TEA, 12 mL) under ice bath conditions. Stir the reaction solution for 15 min, slowly add acryloyl chloride (719 μL, 8.7 mmol), stir for 4 h, wash the reaction solution twice with saturated aqueous NaHCO3 and brine respectively, dry over Na2SO4, concentrate by rotary evaporation, and purify by column chromatography to obtain the white product S1-1.

[0071]

[0072] ② Dissolve the compound S1-1 (1 g, 2.19 mmol) in 80 ml of ultradry dichloromethane, stir under nitrogen for 20 minutes, add (3-mercaptopropyl)triethoxysilane (1.31 g, 5.5 mmol) and continue to stir for 20 minutes under argon conditions, then add triethylamine (2.2 g, 21.9 mmol) and stir for 6 h under argon conditions. Rotate and evaporate to dryness, and elute through silica gel column chromatography to obtain the colorless oily product S1. 11H NMR (400 MHz, Chloroform-d) δ 7.24 - 7.20 (m, 4H), 7.10 (s, 4H), 7.01 - 6.96 (m, 4H), 3.82 (q, J = 7.0 Hz, 12H), 2.90 - 2.81 (m, 8H), 2.63 - 2.58 (m, 4H), 1.78 - 1.69 (m, 4H), 1.65 (s, 12H), 1.22 (t, J = 7.0 Hz, 18H), 0.78 - 0.72 (m, 4H). 13 13C NMR (101 MHz, Chloroform-d) δ 170.62, 148.41, 148.30, 147.52, 127.83, 126.35, 120.77, 58.42, 42.29, 35.13, 30.82, 26.86, 23.20, 18.32, 9.88. HRMS (ESI) m / z: [M+Na] + Calculated for, [C 48 H 74 O 10 S2Si2Na] + : 953.4262; Found: 953.4158.

[0073] The UV-visible absorption spectrum of the phosphorescent molecule P1 synthesized in this invention in acetonitrile solution, the fluorescence emission spectrum in dichloromethane solution, and the delayed fluorescence spectrum at 77 K in dimethyltetrahydrofuran solution are as shown in Figure 2 and 3 . The absorption spectrum shows an absorption peak of the phosphorescent molecule P1 at 200 - 310 nm, a fluorescence spectrum at 371 nm, whose emission intensity is not affected by oxygen, and the emission peak at 504 nm at 77 K is a phosphorescence peak.

[0074] (3) Preparation of aqueous two-component phosphorescent silica nanoparticles:

[0075] Add 100 mg of poloxamer F127, the required amount of phosphorescent molecule P1, and the required amount of barrier molecule S1 to a 20 mL glass bottle, dissolve with 2 mL of ultradry dichloromethane, stir the mixture evenly, and then leave it undisturbed until the dichloromethane completely evaporates. Add 68 mg of sodium chloride and acetic acid (1 M, 1560 μmmol), stir the above mixture for 3 hours at 25 °C to redissolve it, then add 180 μL of tetraethoxysilane, continue stirring for 3 hours, and then add TMSCl to terminate the reaction. The mixture is stirred at 25 °C for 48 h, and the resulting solution is diluted with 5 mL of water and purified by dialysis to obtain silica nanoparticles doped with phosphorescent molecules and barrier molecules, denoted as P1 x％ S1 y％ @NPs. The morphology is as shown inFigure 4 As shown, the particle size of the binary-component phosphorescent nanoparticles is about 10 nm.

[0076] Referring to the preparation process of the aqueous binary-component phosphorescent silica nanoparticles, the raw materials were fed respectively according to the molar ratio of phosphorescent molecule P1, blocker molecule S1 and tetraethoxysilane of 0.01: (0.01 / 0.02 / 0.05 / 0.07): 1 to complete the preparation of phosphorescent nanoparticles P1 1％ S1 1％ @NPs, P1 1％ S1 2％ @NPs, P1 1％ S1 5％ @NPs, P1 1％ S1 7％ @NPs.

[0077] Referring to the preparation process of the aqueous binary-component phosphorescent silica nanoparticles, the difference is only that the blocker molecule S1 is not added and the molar ratio of phosphorescent molecule P1 and tetraethoxysilane is controlled to be 0.01:1. The obtained nanoparticles are denoted as P1 1％ @NPs. The positions of its absorption peak and emission peak are the same as those of Figure 2 and Figure 3 The obtained results are consistent, as shown in Figure 5 and 6 It is proved that the phosphorescent molecule P1 is successfully doped into the silica nanoparticles.

[0078] Referring to the preparation process of the aqueous binary-component phosphorescent silica nanoparticles, the difference is only that the phosphorescent molecule P1 is not added and the molar ratio of blocker molecule S1 and tetraethoxysilane is controlled to be 0.05:1. The obtained nanoparticles are denoted as S1 5％ @NPs. As can be seen from Figure 7 , the absorption peak position of the blocker molecule S1 is in the wavelength range of 200 to 280 nm. Therefore, after being co-doped with the phosphorescent molecule P1 into the silica nanoparticles, when the excitation wavelength is 285 nm, the blocker molecule will not be excited, as shown in Figure 8 When the blocker molecule S1 is excited with a wavelength of 285 nm, no phosphorescent emission appears. Therefore, the introduction of the blocker molecule S1 will not interfere with the luminescence properties of the phosphorescent molecule P1.

[0079] (4) Performance study of aqueous binary-component phosphorescent silica nanoparticles

[0080] As shown in Figure 9As shown, after introducing the blocker molecule S1, two new absorption peaks appear in the absorption spectrum at 265 nm and 273 nm respectively. As the doping ratio of the blocker molecule S1 increases, the absorption peaks continuously increase, which proves that the spacer has been successfully incorporated into the co-assembled silica nanoparticles. Comparing the phosphorescence intensities ( Figures 10 - 11 ) before and after adding the blocker molecule, after adding the blocker molecule, under the same conditions, the phosphorescence intensity at 504 nm is significantly enhanced, and this intensity continuously increases with the increase of the doping ratio of the blocker molecule. When the doping ratio of the blocker molecule S1 is 7%, that is, P1 1％ S1 7％ @NPs, the phosphorescence intensity reaches the peak. In addition, as Figure 12 shown, the measured average phosphorescence lifetime is consistent with the trend of the phosphorescence intensity, and gradually extends with the increase of the doping ratio of the blocker molecule S1. The average phosphorescence lifetimes of P1 1％ S1 5％ @NPs and P1 1％ S1 7％ @NPs are about 6 ms. As Figure 13 shown, the phosphorescence quantum yields of different ratios of P1 1％ S1 y％ @NPs were measured and compared. When the doping ratio of the blocker molecule S1 is 7% (P1 1％ S1 7％ @NPs), the phosphorescence quantum yield reaches 18.2%, which is 45 times higher than that of P1 1％ @NPs. And based on the obtained phosphorescence quantum yield and using the current silica nanoparticle model, according to the data reported in the literature (D. Genovese, S. Bonacchi, R. Juris, M. Montalti, L. Prodi, E. Rampazzo, N. Zaccheroni, Angew. Chem. Int. Ed. 2013, 52, 5965 - 5968.), the linear relationship between the doping ratio and the number of phosphorescent molecules contained in a single silica nanoparticle is obtained, as Figure 14 shown. According to the fitting equation, the number of phosphorescent molecules at different doping ratios was obtained, and combined with the molar extinction coefficient of the nanoparticles, the phosphorescence brightness at each doping ratio was obtained. As Figure 15 shown, when the doping ratio of the blocker molecule S1 is 7%, the phosphorescence brightness is 98578 M -1 cm -1 , compared with P1 1％Compared with @NPs, the phosphorescence brightness of the two-component phosphorescent nanoparticles increased by 85 times, proving that the introduction of the barrier effectively increased the distance between phosphorescent molecules, reduced the interaction between phosphorescent molecules, isolated and prohibited the formation of phosphorescent aggregates, and formed more rigid silica nanoparticles, effectively suppressing non-radiative deactivation, ensuring effective phosphorescent emission, and increasing the phosphorescence lifetime.

[0081] Comparative Example 1

[0082] (1) Synthesis of the barrier molecule S2:

[0083] ① Dissolve bisphenol A (3 g, 13.14 mmol) in 200 mL of THF, then add TEA (12 mL) under an ice bath, stir the reaction solution for 15 min, slowly add propionyl chloride (39.42 mmol, 3.3 mL), stir for 4 h, wash the reaction solution twice with saturated aqueous NaHCO3 and brine, dry with Na2SO4, concentrate by rotary evaporation, and purify by column chromatography to obtain a white product S2-1. 1 H NMR (600 MHz, Chloroform-d) δ 7.26 - 7.22 (m, 4H), 7.06 - 7.00 (m, 4H), 6.57 (dd, J = 17.3, 1.3 Hz, 2H), 6.29 (dd, J = 17.3, 10.4 Hz, 2H), 5.96 (dd, J = 10.4, 1.3 Hz, 2H), 1.67 (s, 6H).

[0084] ② Dissolve the compound S2-1 (2.75 g, 8.17 mmol) in 200 mL of ultra-dry dichloromethane, add mercaptopropyltriethoxysilane (5.847 g, 24.5 mmol), stir under nitrogen for 20 min, then add triethylamine (8.26 g, 81.7 mmol), and stir under nitrogen for 6 h. Concentrate the reaction solution by rotary evaporation and purify by column chromatography to obtain a colorless oily product S2. 1 HNMR (400 MHz, Chloroform-d) δ 7.24 - 7.18 (m, 4H), 7.01 - 6.97 (m, 4H), 3.82 (q, J = 7.0 Hz, 12H), 2.85 (td, J = 10.8, 10.2, 4.5 Hz, 8H), 2.61 (t, J = 7.3 Hz, 4H), 1.78 - 1.69 (m, 4H), 1.66 (s, 6H), 1.22 (t, J = 7.0 Hz, 18H), 0.78 - 0.71 (m, 4H). 13¹³C NMR (101 MHz, Chloroform-d) δ 170.61, 148.54, 147.94, 127.83, 120.90, 58.42, 42.50, 35.13, 30.95, 26.84, 23.20, 18.32, 9.88. HRMS (ESI) m / z: [M+Na] + Calcd for 39 C 64 H 10 O + S₂Si₂Na: 835.3364; Found, 835.3479.

[0085]

[0086] (2) Preparation of aqueous two-component phosphorescent silica nanoparticles:

[0087] Add 100 mg of poloxamer F127, the required amount of phosphorescent molecule P1 and the required amount of blocker molecule S₂ into a 20 mL glass bottle, dissolve with 2 mL of ultradry dichloromethane, stir the mixture evenly, and then leave it undisturbed until the dichloromethane completely evaporates. Add 68 mg of sodium chloride and glacial acetic acid (1 M, 1560 μmmol), stir the above mixture for 3 hours at 25 °C to redissolve, then add 180 μL of tetraethoxysilane, continue stirring for 3 hours, and then quench with TMSCl. The mixture is stirred at 25 °C for 48 h. The resulting solution is diluted with 5 mL of water and purified by dialysis to obtain silica nanoparticles doped with phosphorescent molecules and blocker molecules, denoted as P1 x％ S₂ y％ @NPs.

[0088] Referring to the preparation process of the above-mentioned aqueous two-component phosphorescent silica nanoparticles, the feeding is carried out according to the molar ratio of phosphorescent molecule P1, blocker molecule S₂ and tetraethoxysilane of 0.01: (0.01 / 0.02 / 0.05 / 0.07): 1 respectively to complete the preparation of phosphorescent nanoparticles P1 1％ S₂ 1％ @NPs, P1 1％ S₂ 2％ @NPs, P1 1％ S₂ 5％ @NPs, P1 1％ S₂ 7％ @NPs.

[0089] Comparative Example 2

[0090] (1) Synthesis of blocker molecule S₃:

[0091] ① Dissolve the compound cinnamic phenol (4 g, 18.84 mmol) in 200 mL of THF, then add triethylamine (15 mL) under an ice bath. Stir the reaction solution for 15 min, and slowly add acryloyl chloride (28.26 mmol, 2.37 mL). Stir for 4 h. The reaction solution is washed twice with saturated aqueous NaHCO3 and brine respectively, dried with Na2SO4, concentrated by rotary evaporation, and purified by column chromatography to obtain the white product S3-1. 1 HNMR(600MHz,Chloroform-d)δ7.27(dd,J=8.4,6.9Hz,2H),7.26-7.21(m,4H),7.20-7.15(m,1H),7.05-7.00(m,2H),6.58(dd,J=17.3,1.3Hz,1H),6.31(dd,J=17.3,10.4Hz,1H),5.99(dd,J=10.5,1.3Hz,1H),1.68(s,6H).

[0092] ② Dissolve the compound S3-1 (2.129 g, 7.99 mmol) in 200 mL of ultra-dry dichloromethane. Stir under nitrogen for 20 min, add mercaptopropyltriethoxysiloxane (3.81 g, 15.99 mmol), continue to stir under nitrogen for 20 min, then add triethylamine (8.07 g, 79.9 mmol), and continue to stir under nitrogen for 6 h. Concentrate the reaction solution by rotary evaporation and purify it by column chromatography to obtain the colorless oil product S3. 1 H NMR(400MHz,Chloroform-d)δ7.29-7.14(m,7H),6.99(d,J=8.5Hz,2H),3.82(q,J=7.0Hz,6H),2.85(dt,J=11.6,5.9Hz,4H),2.61(t,J=7.4Hz,2H),1.74(q,J=7.8Hz,2H),1.67(s,6H),1.22(t,J=7.0Hz,9H),0.79-0.71(m,2H). 13 C NMR(101MHz,Chloroform-d)δ170.62,150.33,148.46,148.29,128.07,127.85,126.79,125.75,120.84,58.43,42.73,35.14,30.85,26.86,23.21,18.34,9.89.HRMS(ESI)m / z:[M+Na] + Calculated value for 27 C 40 H + O5SSiNa]:527.2261; found:527.2366.

[0093]

[0094]

[0095] (2) Preparation of aqueous two-component phosphorescent silica nanoparticles:

[0096] Add 100 mg of poloxamer F127, the required amount of phosphorescent molecule P1, and the required amount of blocker molecule S3 to a 20 mL glass bottle, dissolve with 2 mL of ultradry dichloromethane, stir the mixture evenly, and then leave it undisturbed until the dichloromethane has completely evaporated. Add 68 mg of sodium chloride and glacial acetic acid (1 M, 1560 μmmol), stir the above mixture for 3 hours at 25 °C to redissolve it, then add 180 μL of tetraethoxysilane, continue stirring for 3 hours, add TMSCl to quench, stir the mixture at 25 °C for 48 h, dilute the resulting solution with 5 mL of water and purify it by dialysis to obtain silica nanoparticles doped with phosphorescent molecules and blocker molecules, denoted as P1 x％ S3 y％ @NPs.

[0097] Referring to the above-mentioned preparation process of aqueous two-component phosphorescent silica nanoparticles, charge materials according to the molar ratio of phosphorescent molecule P1, blocker molecule S3, and tetraethoxysilane of 0.01:(0.01 / 0.02 / 0.05 / 0.07):1 respectively to complete the preparation of phosphorescent nanoparticles P1 1％ S3 1％ @NPs, P1 1％ S3 2％ @NPs, P1 1％ S3 5％ @NPs, P1 1％ S3 7％ Preparation of @NPs.

[0098] Test the phosphorescent properties of the aqueous two-component phosphorescent silica nanoparticles of Comparative Example 1 and Comparative Example 2, see Figures 16 - 17 , and it can be found that: in terms of phosphorescent brightness ( Figure 16 ), the phosphorescent brightness after introducing blocker molecule S1 is better than that after introducing blocker molecules S2 and S3. When the doping ratio of the blocker molecule is 7%, the phosphorescent brightness of P1 1％ S2 7％ @NPs and P1 1％ S3 7％ @NPs are only 23259 M -1 cm -1 and 2095 M -1 cm -1, Refer to the calculation process of Example 1, and the phosphorescence quantum yields are only 6.08% and 0.53%. In terms of the average phosphorescence lifetime, P1 1％ S2 7％ @NPs and P1 1％ S3 7％ @NPs is also much lower than P1 1％ S1 7％ @NPs( Figure 17 ), which is because the steric groups of the barrier molecules S2 and S3 are relatively small, resulting in insufficient intermolecular spatial separation of the phosphorescent molecule P1 in the inner core, so the brightness is relatively low.

[0099] Example 2

[0100] (1) Synthesis of the phosphorescent molecule P2:

[0101]

[0102] Dissolve 4-bromo-1,8-naphthalic anhydride (0.6 g, 1.2 mmol) in 40 mL of absolute ethanol, purify with nitrogen for 20 min, then add 3-aminopropyltriethoxysilane (560 μL, 2.4 mmol). The resulting solution is refluxed under nitrogen for 5 hours, cooled to room temperature, and then placed in a -20 °C refrigerator overnight. The precipitate is filtered, collected, and purified by column chromatography to obtain a pale yellow product P2. 1 H NMR (400 MHz, Chloroform-d) δ8.58 (d, J = 7.2 Hz, 1H), 8.48 (d, J = 8.6 Hz, 1H), 8.34 (d, J = 7.8 Hz, 1H), 7.97 (d, J = 7.9 Hz, 1H), 7.78 (t, J = 8.0 Hz, 1H), 4.13 (t, J = 7.3 Hz, 2H), 3.81 (q, J = 7.1 Hz, 6H), 1.83 (t, J = 8.1 Hz, 2H), 1.20 (t, J = 7.1 Hz, 9H), 0.74 (t, J = 8.5 Hz, 2H). 13 C NMR (101 MHz, Chloroform-d) δ163.44, 163.42, 133.06, 131.91, 131.09, 131.00, 130.50, 130.06, 128.89, 128.00, 123.10, 122.24, 58.41, 42.99, 21.51, 18.29, 8.02. HRMS (ESI) m / z: [M+Na] + Calculated value [C 21 H 26 NO5SiNaBr] + , 504.0638; Measured value: 504.0623.

[0103] (2) Preparation of aqueous two-component phosphorescent silica nanoparticles:

[0104] Add 100 mg of poloxamer F127, the required amount of phosphorescent molecule P2, and the required amount of blocker molecule S1 into a 20 mL glass bottle, dissolve them with 2 mL of ultradry dichloromethane, stir the mixture evenly, and then leave it undisturbed until the dichloromethane completely evaporates. Add 68 mg of sodium chloride and glacial acetic acid (1 M, 1560 μmmol), stir the above mixture for 3 hours at 25 °C to redissolve it, then add 180 μL of tetraethoxysilane, continue stirring for 3 hours, and then add TMSCl to quench. The mixed solution is stirred at 25 °C for 48 h. The obtained solution is diluted with 5 mL of water and purified by dialysis to obtain silica nanoparticles doped with phosphorescent molecules and blocker molecules, denoted as P2 x％ S1 y％ @NPs.

[0105] Referring to the preparation process of the aforementioned aqueous two-component phosphorescent silica nanoparticles, charge materials according to the molar ratio of phosphorescent molecule P2, blocker molecule S1, and tetraethoxysilane of 0.01:(0.01 / 0.02 / 0.05 / 0.07):1 respectively to complete the preparation of phosphorescent nanoparticles P2 1％ S1 1％ @NPs, P2 1％ S1 2％ @NPs, P2 1％ S1 5％ @NPs, P2 1％ S1 7％ Preparation of @NPs.

[0106] Referring to the preparation process of the aforementioned aqueous two-component phosphorescent silica nanoparticles, the difference is only that the blocker molecule S1 is not added and the molar ratio of phosphorescent molecule P2 and tetraethoxysilane is controlled to be 0.01:1. The obtained nanoparticles are denoted as P2 1％ @NPs.

[0107] Example 3

[0108] (1) Synthesis of phosphorescent molecule P3:

[0109]

[0110] Dissolve fluoro-9-carboxylic acid (1 g, 4.75 mmol), 3-aminopropyltriethoxysilane (1.57 g, 7.13 mmol), EDCl (1.4 g, 7.13 mmol), HOBt (963.4 mg, 7.13 mmol) and triethylamine (TEA, 991 μL, 7.13 mmol) in 250 mL of ultradry dichloromethane, and stir overnight at room temperature. Then evaporate the ultradry dichloromethane completely under reduced pressure, and obtain the white solid product P3 by column chromatography. 1 HNMR (600 MHz, DMSO-d6) δ 8.35 (s, 1H), 7.87 (dd, J = 7.6, 1.2 Hz, 2H), 7.52 - 7.47 (m, 2H), 7.44 - 7.38 (m, 2H), 7.31 (td, J = 7.5, 1.2 Hz, 2H), 4.78 (s, 1H), 3.75 (q, J = 7.0 Hz, 5H), 3.11 (q, J = 6.6 Hz, 2H), 1.52 (dt, J = 15.6, 7.2 Hz, 2H), 1.15 (t, J = 7.0 Hz, 8H), 0.62 - 0.56 (m, 1H). 13 C NMR (101 MHz, DMSO-d6) δ 169.37, 143.00, 141.29, 127.58, 127.11, 124.70, 120.06, 57.68, 54.72, 41.57, 22.77, 18.20, 7.30. HRMS (ESI) m / z: [M+Na] + Calculated value for [C 23 H 41 NO4SiNa] + , 436.1910; Found: 436.2022.

[0111] (2) Preparation of aqueous two-component phosphorescent silica nanoparticles:

[0112] Add 100 mg of poloxamer F127, the required amount of phosphorescent molecule P3 and the required amount of blocker molecule S1 to a 20 mL glass bottle, dissolve with 2 mL of ultradry dichloromethane, stir the mixture evenly, and then leave it undisturbed until the dichloromethane has completely evaporated. Add 68 mg of sodium chloride and acetic acid (1 M, 1560 μmmol), stir at 25 °C for 3 hours to redissolve the above mixture, then add 180 μL of tetraethoxysilane, continue stirring for 3 hours, then add TMSCl to quench, stir the mixture at 25 °C for 48 h, dilute the resulting solution with 5 mL of water and purify it by dialysis to obtain silica nanoparticles doped with phosphorescent molecules and blocker molecules, denoted as P3 x％ S1 y％ @NPs.

[0113] Referring to the preparation process of the aforementioned aqueous two-component phosphorescent silica nanoparticles, the raw materials were fed respectively according to the molar ratio of phosphorescent molecule P3, blocker molecule S1 and tetraethoxysilane of 0.01:(0.01 / 0.02 / 0.05 / 0.07):1 to complete the preparation of phosphorescent nanoparticles P3 1％ S1 1％ @NPs, P3 1％ S1 2％ @NPs, P3 1％ S1 5％ @NPs, P3 1％ S1 7％ @NPs.

[0114] Referring to the preparation process of the aforementioned aqueous two-component phosphorescent silica nanoparticles, with the difference that the blocker molecule S1 was not added and the molar ratio of phosphorescent molecule P3 and tetraethoxysilane was controlled at 0.01:1, the obtained nanoparticles were denoted as P3 1％ @NPs.

[0115] The prepared P2 1％ S1 7％ @NPs, P3 1％ S1 7％ @NPs, P2 1％ @NPs, P3 1％ @NPs was tested for its phosphorescent properties. Refer to Figure 18 , and it was found that: P2 1％ @NPs and P3 1％ @NPs had very low Φ P values at a doping ratio of 1%, while the two-component phosphorescent nanoparticles co-assembled with the blocker molecule S1 showed significantly superior phosphorescent emission characteristics. For example, the phosphorescent brightness of P2 1％ @NPs was 408 M -1 cm -1 , Φ P was 0.13%, while P2 1％ S1 7％ @NPs showed bright orange phosphorescence, with a phosphorescent brightness of 5177 M -1 cm -1 , Φ P was 1.5%, which was about 12.6 times higher than that of P2 1％ @NPs, and the phosphorescent lifetime increased from 0.32 ms to 2.10 ms. For P3 1％ @NPs in the blue region, the Φ P value and brightness value in water were 0.34% and 1579 M -1 cm -1 , respectively, while P3 1％ S1 7％The brightness of @NPs is 7659 M -1 cm -1 , which is about 4.8 times that of P3 1％ @NPs, and the phosphorescence lifetime increases from 4.13 μs to 7.56 μs. The above results indicate that introducing the barrier molecule S1 can effectively prevent the aggregation and self-quenching of different phosphorescent molecules. The barrier effect of the barrier molecule S1 is applicable to phosphorescent molecules with different molecular structures and colors, not only improving the phosphorescence brightness and phosphorescence quantum yield, but also prolonging the phosphorescence lifetime.

[0116] Example 4

[0117] As Figure 19 shown, P1 1％ @NPs and P1 1％ S1 7％ @NPs aqueous solutions were used as color developers, and "clover" and "TIPC" were respectively drawn on ordinary black paper. It can be seen that only the high-brightness P1 1％ S1 7％ @NPs ink shows the corresponding information under ultraviolet light.

[0118] As Figure 20 shown, water and P1 1％ S1 7％ @NPs aqueous solutions were used to write 7 and 421 respectively. Under the fluorescent lamp, the wrong password 7421 written by the two color developers can be seen, while under the ultraviolet light irradiation, the correct green password 421 is shown, demonstrating the application potential of aqueous two-component phosphorescent silica nanoparticles in information display and information encryption.

[0119] Example 5

[0120] As Figure 21 and 22 shown, P1 1％ @NPs, P2 1％ @NPs, P3 1％ @NPs, P1 1％ S1 7％ @NPs, P2 1％ S1 7％ @NPs, P3 1％ S1 7％ @NPs were doped into the polymer PVA100. The brightness of the PVA films of the three two-component phosphorescent nanoparticles doped with the barrier molecule is higher than that of the PVA films of the single-component phosphorescent nanoparticles without the doped barrier molecule.

[0121] And the obtained PVA films P1 1％ @NPs@PVA100 and P1 1％ S1 7％@NPs@PVA100 were respectively made into the shape of a tree. Under the irradiation of 254 nm ultraviolet light, the phosphorescence brightness of the tree with blocker molecules was significantly higher than that of the tree without blocker molecules, indicating that the two-component phosphorescent nanoparticles prepared by the present invention achieved cross-use with the polymer film, and jointly showed an effective improvement in phosphorescence brightness after introducing the spacer.

[0122] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A water-phase two-component phosphorescent silica nanoparticle, characterized in that, The phosphorescent silica nanoparticles are nanoparticles with a surfactant as the outer shell and an assembly formed by hydrolysis and condensation of phosphorescent molecules, blocker molecules, and silicon precursor molecules as the inner core. In the inner core, the phosphorescent molecules are separated by the blocker molecules to prevent aggregation and self-quenching. Among them, the phosphorescent molecule is selected from one of the following general formula structures: R is selected from one of the following structures: X is selected from any one of Cl, Br, and I; R1 is selected from any one of H, CH3, and C2H5; The blocker molecule is selected from the compounds with the following structures:

2. The phosphorescent silica nanoparticles according to claim 1, characterized in that, The phosphorescent molecule is selected from one of the following structures:

3. The phosphorescent silica nanoparticles according to claim 1, wherein, The silicon precursor molecule is selected from tetraethoxysilane, and the surfactant is selected from poloxamer F127.

4. The phosphorescent silica nanoparticles according to claim 1, wherein The particle size of the phosphorescent silica nanoparticles is 10.2 ± 0.7 nm.

5. The preparation method of the phosphorescent silica nanoparticles according to any one of claims 1-4, characterized in that, It includes the following steps: Add the phosphorescent molecule, blocker molecule, and surfactant to ultradry dichloromethane. After mixing evenly, evaporate the organic solvent. Add solid NaCl and glacial acetic acid to redissolve the above materials, and then add the silicon precursor molecule. React at 20 - 30 °C for 2.5 - 3.5 h. After the reaction is completed, terminate the reaction with trimethylchlorosilane. After stirring at a constant temperature for 24 - 48 h, add deionized water for dilution, and dialysis to obtain the product.

6. The preparation method according to claim 5, characterized in that, The molar ratio of the phosphorescent molecule to the blocker molecule is 1:1 - 1:7; The molar ratio of the phosphorescent molecule to the silicon precursor molecule is 0.0001 - 0.008:

1.

7. The preparation method according to claim 5, wherein The mass ratio of the surfactant to the silicon precursor molecule is 100:

169.

8. The preparation method according to claim 5, wherein, The cut-off molecular weight of the dialysis bag used during dialysis is 8000 - 14000.

9. The application of the phosphorescent silica nanoparticles according to any one of claims 1 - 4 in information display, information encryption, and preparation of flexible luminescent materials.

10. The application according to claim 9, characterized in that, The specific application is to use the aqueous two-component phosphorescent silica nanoparticles as a chromogenic agent in information display and information encryption; or to dope the aqueous two-component phosphorescent silica nanoparticles into a polymer to prepare a polymer film with phosphorescent emission.

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