Photochemical long afterglow system, preparation method and application thereof

Abstract

The application belongs to the technical field of luminescent materials, and discloses a photochemical long-afterglow system, a preparation method and application thereof.The photochemical long-afterglow system mainly comprises a photosensitizer, a light energy storage unit and an emitter which are tightly combined through coordination.The working principle is that the photosensitizer generates singlet oxygen under the irradiation of excitation light, the singlet oxygen reacts with the light energy storage unit to generate an epoxy structure intermediate, the excited state photooxidation product is generated after chemical excitation, and the energy is transferred to the emitter, the emitter releases photons, and then the afterglow light is realized.The construction idea of the system greatly widens the selection range of the intermediate and the emitter in the photochemical long-afterglow system, and provides a new idea for improving the luminescent quantum yield and luminous brightness of the photochemical long-afterglow.

Description

Technical Field

[0001] This invention belongs to the field of luminescent materials technology, and more specifically relates to a photochemical long afterglow system, its preparation method and application. Background Technology

[0002] Long-persistent luminescence is a unique luminescence phenomenon that allows photons to be emitted continuously (typically exceeding 100 milliseconds) after the excitation light is turned off. This unique property makes long-persistent luminescent materials widely used in fields such as anti-counterfeiting, multi-dimensional displays, information storage, and encryption. In particular, because long-persistent luminescence does not require real-time excitation by an excitation light, but rather converts light energy into chemical energy through pre-irradiation to achieve luminescence, this luminescence process is free from excitation light background interference. This eliminates interference from autofluorescence in biological organisms and scattering interference from excitation light, thus significantly reducing background signals. Therefore, it can be applied to time-resolved detection and imaging. Compared with traditional time-resolved technologies, this time-resolved technology based on long-persistent luminescence does not require complex and precise instruments and operations, thereby greatly expanding its applications in the biomedical field. Currently, long-persistent luminescent materials are mainly divided into two categories: inorganic materials with energy traps in lattice defects and organic phosphors with long-lived triplet excited states.

[0003] Recently, a novel long-afterglow material system based on cascade photochemical reactions has attracted widespread attention. This photochemical long-afterglow system typically consists of three parts: 1) photosensitizer: generating singlet oxygen (… 1 O2); 2) Photoenergy cache unit (PCU): with 1 O2 reacts to produce excited photo-oxidation products; 3) Emitter: accepts energy from the photo-oxidation products and releases photons, producing afterglow. Because photochemical long-persistence systems can be modularly designed, the luminescence characteristics (wavelength, lifetime, and intensity) of the entire system are tunable. Furthermore, photochemical long-persistence systems are not limited by rigid environments (such as crystal, polymer, or powder states), thus achieving highly bright luminescence in solution phases. These advantages make photochemical long-persistence systems ideal candidates for in vivo fluorescence imaging. Generally, the luminescence quantum yield is an important parameter for evaluating the performance of afterglow materials in bioimaging. Typically, we use photosensitizers with high singlet oxygen yields and emitters with high fluorescence quantum yields to construct efficient photochemical long-persistence systems. However, in practical applications, the luminescence quantum yield remains one of the biggest limitations to the widespread application of photochemical long-persistence systems. Currently, corresponding strategies have been proposed to overcome this limitation, such as covalent coupling and molecular fusion. However, the enhancement of quantum yield brought about by these strategies is still limited (<5%). Therefore, the luminescence quantum yield of photochemical long afterglow systems still needs to be improved.

[0004] Therefore, how to provide a photochemical long afterglow system with high luminescence quantum yield and strong luminescence brightness, as well as its preparation method and application, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To overcome the shortcomings and deficiencies of existing technologies, this invention provides a photochemical long-persistence system based on torsional intramolecular charge transfer, its preparation method, and its applications. This long-persistence system, through intramolecular energy transfer, can achieve a luminescence quantum yield of up to 27.5% in the solution phase, which is higher than the luminescence quantum yield of all publicly disclosed photochemical long-persistence systems in the prior art. This enables the construction of an ultra-bright long-persistence system, and thus has broad application prospects in the fields of bioimaging, homogeneous detection, and immunochromatographic detection.

[0006] The photochemical long afterglow system of this invention mainly comprises: a photosensitizer, and a light energy buffer unit and an emitter tightly bound together through coordination. Its working principle is that the photosensitizer generates singlet oxygen under excitation light irradiation. The singlet oxygen reacts with the light energy storage unit to generate an epoxy intermediate, which, after chemical excitation, generates an excited-state photo-oxidation product and transfers energy to the emitter. The emitter then releases photons, thereby achieving afterglow luminescence.

[0007] Furthermore, the inventors discovered that the long-persistence system of this invention can achieve ultra-bright long-persistence bioimaging, with a high signal-to-background ratio (SBR) of up to 655, nearly 80 times higher than that of corresponding fluorescence imaging, demonstrating enormous potential for in vivo persistent-persistence bioimaging. In addition, this long-persistence system can also be used for immunochromatographic detection, enabling highly sensitive detection of macromolecular antigens. Utilizing the construction concept of this system, this invention greatly broadens the selection range of intermediates and emitters for photochemical long-persistence systems and provides new ideas for improving the luminescence quantum yield and luminescence brightness of photochemical long-persistence systems.

[0008] In this application, the term "photochemical reaction" refers to a series of chain reactions, including photochemical addition, photooxidation, photochemical dissociation, and bond breaking and recombination.

[0009] In this application, the term "cascade reaction" is a chemical process comprising at least two consecutive reactions, each subsequent reaction occurring solely by means of the chemical function formed in the preceding step.

[0010] In this application, the term "photosensitizer" refers to a substance that absorbs photons and transfers the absorbed light energy to reactants in various forms, without changing its own mass and chemical properties before and after the chemical reaction. It can transfer excited-state energy to reactants through various pathways such as free radical initiation, redox reactions, and energy transfer. In addition to achieving the functions of traditional photocatalysts and photoinitiators, photosensitizers have a wider absorption range, utilize a wider wavelength range of sunlight, and have higher absorption and conversion efficiency. Normal substrates rarely generate their triplet intermediates directly through photoexcitation. However, if a photosensitizer is added to the system, its ground-state molecule will be excited by photoexcitation after absorbing photons, generating a singlet excited-state molecule. The photosensitizer is more likely to generate triplet intermediates through intersystem crossing, and its triplet intermediate has a long lifetime, sufficient to induce other substrates to generate corresponding triplet intermediates. These advantages enable the photochemical reaction process involving photosensitizers to generate more reaction intermediates and facilitates effective control of the reaction. In some contexts, "photosensitizer" can also be understood as a light absorber, which can be a traditional photosensitizing reagent or other energy donor materials.

[0011] In this application, the term "emitter" can be understood as "luminescent agent" or "luminescent unit" in some contexts. It generally refers to a substance that can ultimately emit energy in the form of light energy. Such substances have luminescent groups and can produce fluorescence or phosphorescence.

[0012] In this application, the term "photoenergy cache unit (PCU)" can be understood as "photochemical storage agent" or "photoenergy storage unit" in some contexts. The "cache unit" is mainly used to undergo a cycloaddition reaction with singlet oxygen to generate an unstable epoxy intermediate, which then forms an excited-state diketone structure, ultimately transferring energy to the emitter. However, in some scenarios, the cache unit differs slightly from the photochemical storage agent. A photochemical storage agent can be understood as long-term storage of photochemical energy, while a cache unit can be understood as short-term storage of photochemical energy. Both cache units and photochemical storage agents can participate in photochemical reactions, but the photochemical reaction products of photochemical storage agents are more stable and can exist for a longer period at room temperature, thus allowing for long-term energy storage. In contrast, the photochemical products of a cache unit are unstable and undergo bond breaking and recombination after short-term storage, simultaneously realizing energy conversion and extraction / transfer processes, thus only allowing for energy caching for a limited time.

[0013] In this application, the term "twisted intramolecular charge transfer (TICT)" refers to the twisting of the planes of some chemical structures in the excited state, which are orthogonal to each other. The spatial separation of the two orbitals in the twisted structure indicates that the excited state can be characterized as an intramolecular charge transfer (ICT) state or a charge separation state, which has a small light emission probability. This phenomenon is called twisted intramolecular charge transfer.

[0014] In this application, unless otherwise specified, the terms "photochemical afterglow system (PA system)," "long afterglow material," and "long afterglow luminescent material" have the same meaning and can be used interchangeably.

[0015] In this application, the term "TADF (thermally activated delayed fluorescence) compound" can be referred to as thermally activated delayed fluorescence material, which is a type of luminescent material. This type of material generally has a small singlet-triplet energy difference, and triplet excitons can be converted into singlet excitons to emit light through antisystem crossing.

[0016] To achieve the above objectives, the present invention adopts the following technical solution:

[0017] A cache unit comprising the chemical structure of formula (I):

[0018]

[0019] In formula (I), X is selected from O or S; R is selected from one of NN ligand, CN ligand, and ON ligand; and n is 1 to 15.

[0020] Preferably, the NN ligand is selected from one or more of the following chemical structures:

[0021]

[0022] Preferably, the CN ligand is selected from one or more of the following chemical structures:

[0023]

[0024] Preferably, the ON ligand is selected from one or more of the following chemical structures:

[0025]

[0026] The beneficial effects of the above technical solution are: NN ligands, CN ligands, and ON ligands, by introducing different nitrogen-containing functional groups, achieve further coordination with the emitter. That is, when the two are linked together by a coordinate bond, this effect shortens the distance between them.

[0027] A photochemical long-afterglow system, the long-afterglow system comprising:

[0028] A) At least one photosensitizer;

[0029] B) At least one emitter;

[0030] C) At least one of the above-mentioned cache units;

[0031] The buffer unit and the emitter form a complex through coordination.

[0032] The beneficial effects of the above technical solution are as follows: Compared with existing long-afterglow material systems, the coordination between the buffer unit and the emitter to form a complex shortens the energy transfer distance, further facilitating intramolecular energy transfer. Furthermore, energy transfer through the TICT state enhances emission, making energy transfer easier. Therefore, the inventors have found in practice that the combination of these two methods significantly improves the luminescence quantum yield.

[0033] Preferably, the molar ratio of the complex to the photosensitizer is 1:10 to 10000.

[0034] In practical research, the long-afterglow luminescence effect can be further optimized by adjusting the molar ratio of the complex to the sensitizer within an appropriate range.

[0035] Preferably, the chemical formula of the complex is ML1L2, where M is the central atom of the complex, L1 is the ligand of the buffer unit, L2 is the diketone ligand of the emitter, L2M is the emitter, and the number of ligands in L1 and L2 can be adjusted according to the central atom of the complex.

[0036] Preferably, the central atom of the complex is selected from one of the lanthanides or a noble metal.

[0037] More preferably, the central atom of the complex is selected from one of Eu, Tb, Sm, Yb, Nd, Dy, Er, Ho, Pr, and Ir.

[0038] The beneficial effects of the above technical solution are: lanthanide metal ions have high coordination numbers and high charges, readily combining with NN, CN, and ON ligands, which facilitates the formation of coordination interactions. Furthermore, in actual complexes, the types of ligands, the number of each ligand, and the total coordination number can vary.

[0039] Preferably, the photosensitizer is selected from one or more of polymethylcyanine dyes, porphyrin and phthalocyanine dyes and their complexes, methylene blue compounds, phycoerythrin, bamboo red pigment, benzophenone compounds, organometallic frameworks, quantum dots, graphene, carbon nanotubes, titanium dioxide semiconductors, and derivatives or copolymers of the above substances.

[0040] More preferably, the photosensitizer is selected from one or more of the following chemical structures:

[0041]

[0042] Preferably, the emitter is selected from one or more of the following: iridium complexes, rare earth complexes, polyfluorene compounds, coumarin compounds, naphthalimide compounds, triphenylene or higher phenylene compounds, rhodamine compounds, fluorescein compounds, fluoroboron dipyrrole compounds, green fluorescent protein, bimane compounds, perovskite luminescent nanomaterials, TADF compounds, and derivatives or copolymers of the above substances.

[0043] Preferably, the long afterglow system further includes a carrier medium for dissolving, dispersing or adsorbing components A, B, and C; the carrier medium is one of an organic solution or an aqueous medium.

[0044] Preferably, the organic solution includes aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, alcohols, esters, and ketones.

[0045] More preferably, the organic solution is selected from one or more of benzene, toluene, xylene, trimethylbenzene, benzyl alcohol, pentane, hexane, octane, petroleum ether, cyclohexane, cyclohexanone, methylcyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, carbon tetrachloride, methanol, ethanol, isopropanol, n-butanol, ethylene glycol, glycerol, diethyl ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, pyridine, phenol, oleic acid, linoleic acid, linolenic acid, octadecene, oleylamine, and liquid paraffin.

[0046] Preferably, the aqueous medium includes nano-dispersion, microsphere dispersion, and nanomicelle dispersion.

[0047] Preferably, the aqueous medium includes purified water, mineral water, distilled water, deionized water, carbonated water, river and lake water, seawater, water bodies containing sufficient soluble substances, serum, plasma, blood containing salt or protein, and water vapor.

[0048] Preferably, the long afterglow system exists in the form of crystals, nanomaterials, powders, thin films, bulk materials, metal-organic frameworks, composites, organic solvent systems, ionic liquids, aqueous solutions, aerosols, gels, sols, and biological media.

[0049] More preferably, the long afterglow system exists in the form of one of nanomaterials, thin films, gels, or biological media.

[0050] The preparation method of the above-mentioned photochemical long afterglow system includes the following steps:

[0051] S1. Halogenating a traditional cache unit and then introducing different functional groups through a Suzuki coupling reaction to form the cache unit as described in claim 1;

[0052] S2. Dissolve the buffer unit formed in step S1 and the diketone ligand L2 of the emitter in an organic solvent, add a salt solution containing the central atom of the complex dropwise, and stir at room temperature for 0-10 hours.

[0053] S3. Filter the mixed solution after stirring in step S2, and dry the obtained solid after purification for 0-48 hours to obtain the complex.

[0054] S4. The complex obtained in step S3 is mixed and dissolved with the photosensitizer in a carrier medium, and then stirred and purified to obtain photochemical long afterglow systems of different forms.

[0055] Preferably, the salt solution is a chloride salt solution.

[0056] The aforementioned photochemical long afterglow system can be used for applications such as bioimaging, homogeneous detection, immunochromatographic detection, surgical navigation, multidimensional display, information storage and encryption, and anti-counterfeiting.

[0057] As can be seen from the above technical solution, compared with the prior art, the present invention provides a photochemical long afterglow system, its preparation method and application, which has the following beneficial effects:

[0058] (1) In the long afterglow system of the present invention, the emitter and the buffer unit are combined by coordination, which shortens the energy transfer path, makes energy transfer easier, and results in higher afterglow intensity and longer life.

[0059] (2) The TICT state formed in the complex of the present invention enhances emission and energy tends to be transferred to the emitter, thus the ratio of photons emitted by the emitter to the absorbed photons is higher.

[0060] (3) Because the long afterglow system in this invention has a high quantum yield and a high signal-to-background ratio in the field of biological imaging, it has great application potential in in vivo biological imaging and other fields. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0062] Figure 1 This is a schematic diagram illustrating the working principle of the photochemical long afterglow system in an embodiment of this application.

[0063] Figure 2 This is a diagram illustrating the luminescence process of a photochemical long afterglow system according to an embodiment of this application.

[0064] Figure 3 The afterglow spectrum of EuTPS and EuTP & SO in DCM solution is shown in the embodiments of this application.

[0065] Figure 4 The afterglow decay curves of EuTPS and EuTP&SO in DCM solution are shown in the embodiments of this application.

[0066] Figure 5 The luminous intensity values ​​of EuTPS, EuTP&SO, and EuTP are for embodiments of this application.

[0067] Figure 6 The images show the afterglow spectra of SO and PhenSO in the embodiments of this application when PdPc is used as a photosensitizer.

[0068] Figure 7 The fluorescence spectra of DBT, SO', and PhenSO' in the embodiments of this application are shown.

[0069] Figure 8 The normalized fluorescence spectra of PhenSO' in different proportions of DCM and EA mixed solvents are shown in the embodiments of this application.

[0070] Figure 9 The normalized fluorescence spectra of PhenSO' in different proportions of DMSO and DMF mixed solvents are shown in the embodiments of this application.

[0071] Figure 10 The basic luminescence principle of the Eu(III) complex in the embodiments of this application is explained.

[0072] Figure 11 The normalized absorption spectrum of TTA and the afterglow spectra of SO and PhenSO are shown in the embodiments of this application.

[0073] Figure 12The images show the afterglow luminescence quantum yield and afterglow photographs of EuTP&SO, EuTP&PhenSO, and EuTPS in DCM solution, as described in the embodiments of this application.

[0074] Figure 13 This is a schematic diagram of the energy transfer mechanism of the EuTPS and EuAPS systems in the embodiments of this application.

[0075] Figure 14 The normalized absorption spectrum of acac and the afterglow spectra of SO and PhenSO are shown in the embodiments of this application.

[0076] Figure 15 The image shows the afterglow spectra of the EuAPS and EuAP&SO systems in DCM solution according to embodiments of this application.

[0077] Figure 16 The fluorescence lifetime of EuAP at 612 nm in DCM solution is shown in the embodiment of this application.

[0078] Figure 17 The fluorescence lifetime of EuTP at 612 nm in DCM solution is shown in the embodiment of this application.

[0079] Figure 18 This is a comparison diagram of the afterglow intensity of the emitters in a traditional SO system and an embodiment of this application.

[0080] Figure 19 These are afterglow photographs of EuAP, EuTP, and different PA systems under 365nm LED illumination, representing embodiments of this application.

[0081] Figure 20 This is a schematic diagram illustrating the preparation of afterglow luminescent nanoparticles EuTPS-N according to an embodiment of this application.

[0082] Figure 21 The images show the DLS results and TEM images of EuTPS-N in aqueous solution, as described in this application.

[0083] Figure 22 The images show the afterglow emission spectrum and afterglow photograph of EuTPS-N in aqueous solution, as described in this application.

[0084] Figure 23 The images show the afterglow decay curve and afterglow photograph of the EuTPS-N aqueous solution in a centrifuge tube, as described in this application.

[0085] Figure 24 This is the quantitative result of afterglow and fluorescence imaging SBR in the embodiments of this application.

[0086] Figure 25 The images show the afterglow and corresponding fluorescence of EuTPS-N injected subcutaneously into live mice, as described in the embodiments of this application. Detailed Implementation

[0087] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0088] The ultrabright photochemical long afterglow system in this application mainly comprises at least one photosensitizer, at least one emitter, and at least one buffer unit. The buffer unit can form a complex with the emitter through coordination. Specifically, it can be understood that the buffer unit contains a ligand that provides lone pair electrons, and the emitter contains a central atom that can provide empty orbitals. Therefore, the buffer unit and the emitter form a complex through coordination. This coordination, or complexation, shortens the energy transfer distance, further facilitating intramolecular energy transfer. In addition, TICT (twisted intramolecular charge transfer) state energy transfer can enhance emission, i.e., make energy transfer easier, referring to... Figure 1 and Figure 2 Taking PhenSO as an example, the energy transfer mechanism of TICT state sensitization can be more easily understood. PhenSO is formed by coordination between PCU molecules and Eu. The photosensitizer generates singlet oxygen under excitation light. The singlet oxygen reacts with PhenSO to generate an epoxy intermediate. In this process, taking Eu(tta)3PhenSO as an example, the plane of the chemical structure of PhenSO will be twisted, and energy will tend to be transferred into the molecule to Eu, which is the TICT state energy transfer mentioned above. Therefore, the energy transfer process is easier, the quantum ratio of light emission is larger, and the quantum efficiency of light emission is higher.

[0089] In some embodiments, the cache unit comprises at least the chemical structure of formula (I):

[0090]

[0091] In formula (I), X is selected from O or S; R is selected from one of NN ligand, CN ligand, and ON ligand; and n is 1 to 15.

[0092] Specifically, NN ligands are selected from one or more of the following chemical structures:

[0093]

[0094] CN ligands are selected from one or more of the following chemical structures:

[0095]

[0096] ON ligands are selected from one or more of the following chemical structures:

[0097]

[0098] The aforementioned NN, CN, and ON ligands achieve further coordination with the emitter by introducing different nitrogen-containing functional groups. That is, when the two are linked together by a coordinate bond, this interaction shortens the distance between them.

[0099] The general formula of the complex formed by the buffer unit and the emitter is L2ML1, where M is the central atom of the complex, L1 is the ligand of the buffer unit, L2 is the diketone ligand, and L2M is the emitter. The number of ligands in L1 and L2 can be adjusted according to the central atom of the complex.

[0100] The central atom of the complex is selected from lanthanides or noble metals, preferably Eu, Tb, Sm, Yb, Nd, Dy, Er, Ho, Pr, or Ir. Lanthanide metal ions have high coordination numbers and high charges, readily combining with N-N, CN, and ON ligands, which facilitates coordination. Furthermore, in actual complexes, the types of ligands, the number of each ligand, and the total coordination number can vary. The nitrogen atom of the buffer unit coordinates with the metal atom of the complex, forming a covalently bonded complex consisting of both buffer and emission units. The ligands coordinate with the central atom via O, N, or C. For rare earth complexes, the coordination number is mostly between 6 and 12.

[0101] The following explanation uses Eu as an example for the central atom of the complex, diketone ligands (or β-diketone ligands) as an example for the ligands, and X=S as an example for the buffer unit PCU molecule to illustrate the structure of the formed complex.

[0102] The structure of the diketone ligand is as follows:

[0103]

[0104] The structure of the corresponding complex formed using NN ligands is as follows:

[0105]

[0106]

[0107]

[0108]

[0109] Taking CN ligands as an example, the structure of one type of corresponding complex formed is as follows:

[0110]

[0111]

[0112] Taking the ON ligand as an example, the structure of one of the corresponding complexes formed is as follows:

[0113]

[0114] The structures of complexes formed by other coordination center atoms such as Tb, Sm, and Ir are as follows:

[0115]

[0116]

[0117] In the embodiments of this application, the photosensitizer is selected from one or more of polymethylcyanine dyes, porphyrin and phthalocyanine dyes and their complexes, methylene blue compounds, phycoerythrin, bamboo red pigment, benzophenone compounds, organometallic frameworks, quantum dots, graphene, carbon nanotubes, titanium dioxide semiconductors, and derivatives or copolymers of the above substances.

[0118] Preferably, the photosensitizer is selected from one or more of the following chemical structures:

[0119]

[0120]

[0121] More preferably, the photosensitizer used in the embodiments of this application is PdPc, whose full English name is Palladium(II)phthalocyanine, CAS number 20909-39-1, and its structural formula is as follows:

[0122]

[0123] The following are some embodiments of the implementation of this application. In order to make the embodiments of this application easier to understand and without repetition, the molecular structures and abbreviations in the context of this application are listed below:

[0124]

[0125] Example 1: Preparation of SO molecules

[0126] The synthesis method is as follows:

[0127]

[0128] 4-(dimethylamino)benzoin and 2-mercaptoethanol are heated to 120°C in trimethylchlorosilane (TMCS) and toluene solvents to give SO.

[0129] The NMR characterization results of the synthesized SO molecules are as follows:

[0130] 1 H NMR (400MHz, Chloroform-d) δ7.23(dd,J=8.1,1.7Hz,2H),7.20-7.07(m,5H),6.59(d,J=7.9Hz,2H),4.63-4.43(m,2H),3.31-3.21(m,2H),2.94(s,6H). 13 C NMR (101MHz, Chloroform-d) δ149.50,144.83,136.90,130.94,128.99,127.56,127.01,126.38,112.21,107.90,65.68,40.50,28.45.

[0131] HRMS for [M+H] + :Calcd.298.1187; Found 298.1266.

[0132] Example 2

[0133]

[0134] The conditions and methods in this embodiment are the same as in Example 1, except that ethylene glycol is used instead of 2-mercaptoethanol to carry out the reaction, resulting in a compound as shown in structure (a).

[0135] Example 3

[0136]

[0137] The conditions and methods in this embodiment are the same as in Example 1, except that the number of carbon chains connected to the N atom on benzoin is increased from 1 to 8, resulting in a compound as shown in structure (b).

[0138] Example 4

[0139]

[0140] The conditions and methods in this embodiment are the same as in Example 1, except that the number of carbon chains connected to the N atom on benzoin is increased from 1 to 16, resulting in a compound as shown in structure (c).

[0141] Example 5: Preparation of BrSO molecules

[0142] The synthesis method is as follows:

[0143]

[0144] SeO2 (3.33 g, 30 mmol, 1.5 eq) and bromoacetophenone (3.00 g, 20.0 mmol, 1 eq) were added to a 100 mL round-bottom flask and refluxed in 30 mL of 1,4-dioxane: H2O = 30:1 overnight at 100 °C. The solvent was removed under reduced pressure, and the mixture was stirred in water for 12 hours. After filtration, 1 was obtained.

[0145] Add 1 (3.0 g, 13.00 mmol, 1 eq) and N,N-dimethylaniline (2 mL, 1 eq) to a round-bottom flask and reflux overnight in 30 mL of benzene under an argon atmosphere at 100 °C. Dry the organic layer with anhydrous Na₂SO₄ and evaporate the organic solvent to dryness. Purify the crude product by silica column chromatography to give 2.

[0146] 2 (2.25 g, 6.7 mmol, 1 eq), 2-mercaptoethanol (1.5 mL, 4 eq), and trimethylchlorosilane (2 mL) were added to a 100 mL three-necked flask equipped with a reflux condenser and refluxed overnight in 15 mL toluene at 130 °C under an argon atmosphere. The mixture was cooled to room temperature, quenched with 30 mL of water, and extracted with dichloromethane. The organic layer was dried over anhydrous Na₂SO₄, and the organic solvent was evaporated to dryness. The crude product was purified by silica gel column chromatography to give a yellow solid.

[0147] The NMR characterization results of the above products are as follows:

[0148] 1 HNMR(400MHz,Chloroform-d)δ7.28-7.20(m,2H),7.06(t,J=9.2Hz,4H),6.79-6.30(m,2H),4.70-4.24(m,2H),3.32-3.13(m,2H),2.94(s,6H).

[0149] HRMS for [M+H] + :Calcd.376.0292;Found376.0371.

[0150] Example 6: Preparation of PhenSO molecules

[0151] The synthesis method is as follows:

[0152]

[0153] PhenSO molecules are prepared from BpinSO and Br-Phen.

[0154] Synthesis of BpinSO: BrSO (3.76 g, 0.01 mol), bis(pinacol)diboron (5.08 g, 0.02 mol), KOAC (2.94 g, 0.03 mmol), and Pd(dppf)Cl2 (220 mg, 0.03 eq) were added to a 100 mL three-necked flask equipped with a reflux condenser, and then refluxed overnight in 20 mL of 1,4-dioxane at 100 °C under an argon atmosphere. The mixture was cooled to room temperature, quenched with 30 mL of water, and extracted with dichloromethane. The organic layer was dried over anhydrous Na2SO4, and the organic solvent was evaporated to dryness. The crude product was purified by silica column chromatography to give a pale yellow solid in 82.6% yield.

[0155] The NMR characterization results of the above products are as follows:

[0156] 1 HNMR(400MHz,Chloroform-d)δ7.60-7.54(m,2H),7.22-7.17(m,2H),7.14-7.06(m,2H ),6.62-6.51(m,2H),4.53-4.49(m,2H),3.26-3.22(m,2H),2.94(s,6H),1.33(s,12H).

[0157] HRMS for [M+H] + :Calcd.424.2039;Found424.2122.

[0158] Synthesis of PhenSO: Br-Phen (1.1 g, 4.26 mmol), BpinSO (2.7 g, 6.39 mmol, 1.5 eq), Pd(PPh3)4 (250 mg, 0.05 eq), and Na2CO3 (2.3 g, 21.5 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser. Then, 1,4-dioxane / ethanol / water (15 mL, 2:1:1) was added to the reaction mixture, and the mixture was refluxed overnight at 100 °C under an argon atmosphere. The mixture was cooled to room temperature, quenched with 30 mL of water, and extracted with dichloromethane. The organic layer was dried over anhydrous Na2SO4, and the organic solvent was evaporated to dryness. The crude product was purified by silica gel column chromatography to give a yellow solid in 53.6% yield.

[0159] The NMR characterization results of the above products are as follows:

[0160] 1HNMR(400MHz,Chloroform-d)δ9.21(dt,J=4.3,1.6Hz,2H),8.27(td,J=8.5,1.7Hz,2H),7.75-7.63(m,2H),7.58(dd,J=8.4,4.3Hz,1 1 3CNMR(101MHz,Chloroform-d)δ150.12,149.95,149.37,146.15,145.43,144.23,138.70,137.13,136.67,136.07,134.74,131.07, 129.19,129.05,128.14,127.84,126.75,126.32,123.39,122.79,112.61,109.00,77.36,77.24,77.04,76.72,65.75,40.72,28.49.

[0161] HRMS for [M+H] + :Calcd.476.1718;Found476.1797.

[0162] Example 7 Synthesis of SO' molecules

[0163] The synthesis method is as follows:

[0164]

[0165] SO (311.98 mg, 1.05 mmol, 1 eq) and PdPc (12 mg, 0.01 eq) were added to a 500 mL reaction flask and stirred in 400 mL of dichloromethane. The mixture was irradiated with a 730 nm laser for 2 hours, followed by quenching with 200 mL of water. The organic layer was dried over anhydrous Na₂SO₄, and the organic solvent was evaporated to dryness. The crude product was purified by silica column chromatography to give a white solid in 90% yield.

[0166] The NMR characterization results of the above products are as follows:

[0167] 1HNMR(400MHz,Chloroform-d)δ8.11-8.06(m,2H),7.94-7.88(m,2H),7.62-7.55(m,1H ),7.49-7.43(m,2H),6.70-6.65(m,2H),4.53(t,J=6.6Hz,2H),3.46(t,J=6.6Hz,2H), 3.08(s,6H).13CNMR(101MHz,Chloroform-d)δ188.48,166.34,153.75,133.01,130.0 6,129.73,129.46,128.37,124.43,110.77,77.36,77.04,76.72,63.81,40.13,27.34.

[0168] HRMS for [M+H] + :Calcd.330.1086; Found330.1164.

[0169] Example 8: Synthesis of PhenSO' molecules

[0170]

[0171] PhenSO4 (500 mg, 1.05 mmol, 1 eq) and PdPc (12 mg, 0.01 eq) were added to a 500 mL reaction flask, and 400 mL of dichloromethane was added with stirring. The mixture was irradiated with a 730 nm laser for 2 hours, followed by quenching with 200 mL of water. The organic layer was dried over anhydrous Na2SO4, and the organic solvent was evaporated to dryness. The crude product was purified by silica column chromatography to give a white solid in 90% yield.

[0172] The NMR characterization results of the above products are as follows:

[0173] 1HNMR(400MHz,Chloroform-d)δ9.27(ddd,J=4.4,2.7,1.7Hz,2H),8.35-8.22(m,4H),7.94-7.89(m,2H),7.81-7.70 (m,2H),7.66-7.61(m,3H),6.70-6.60(m,2H),4.60(t,J=6.5Hz,2H),3.51(t,J=6.5Hz,2H),3.07(s,6H).13CNMR(1 01MHz,Chloroform-d)δ188.42,165.99,153.86,150.45,150.21,145.89,145.37,143.43,137.98,136.45,134.53 ,130.09,130.03,129.83,129.48,128.00,127.54,126.75,124.18,123.63,123.15,110.63,64.06,40.06,27.33.

[0174] HRMS for [M+H] + :Calcd.508.1617; Found508.1695.

[0175] Example 9: Synthesis of PBM molecules

[0176] The synthesis method is as follows:

[0177]

[0178] Pinarol 4-methoxycarbonylphenylboronic acid (0.63 g, 2.4 mmol, 1.2 eq), 1,10-phenanthroline (0.52 g, 2.0 mmol, 1 eq), Pd(PPh3)4 (0.12 g, 5%), and K2CO3 (0.55 g, 4.0 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser and refluxed in 12 mL of 1,4-dioxane:H2O = 4:1. The mixture was incubated overnight at 110 °C under an argon atmosphere. The solution was cooled to room temperature, quenched with 30 mL of water, and extracted with dichloromethane. The organic layer was dried over anhydrous Na2SO4, and the organic solvent was evaporated to dryness. The crude product was purified by silica gel column chromatography to give an ivory-white solid.

[0179] The NMR characterization results of the above products are as follows:

[0180] 1HNMR (400MHz, DMSO-d6) δ9.15 (ddd, J=4.3, 3.6, 1.7Hz, 2H), 8.56 (dd, J=8.1, 1.8Hz, 1H), 8.23 ​​(dd ,J=8.4,1.7Hz,1H),8.21-8.14(m,2H),8.03(s,1H),7.83(dd,J=8.1,4.3Hz,1H),7.80-7.73(m,3 H),3.94(s,3H).13CNMR(101MHz,DMSO-d6)δ166.51,150.85,150.40,146.18,145.63,143.70,13 7.38,136.95,134.29,130.81,129.98,129.62,128.22,127.61,127.24,124.24,123.88,52.81.

[0181] HRMS for [M+H] + :Calcd.315.1055; Found315.1133.

[0182] Example 10: Synthesis of DBT molecules

[0183] The synthesis method is as follows:

[0184]

[0185] 4-(dimethylamino)benzoic acid (1.0 g, 6.0 mmol, 1 eq) and 5 mL of thionyl chloride were added to a round-bottom flask and refluxed for 1 hour. Excess thionyl chloride was removed by rotary evaporation to obtain solid 4-(dimethylamino)benzoyl chloride. The dried benzoyl chloride was then added to dichloromethane along with equal volumes of triethylamine and ethanethiol. The organic layer was dried over anhydrous Na₂SO₄, and the organic solvent was evaporated to dryness. The crude product was purified by silica column chromatography to give a white, flaky solid.

[0186] The NMR characterization results of the above products are as follows:

[0187] 1 HNMR(400MHz,Chloroform-d)δ7.94-7.85(m,2H),6.71-6.65(m,2H),3.07(s,8H),1.35(t,J=7.4Hz, 3H).13CNMR(101MHz,Chloroform-d)δ189.93,153.46,129.22,125.18,110.83,40.22,23.01,15.13.

[0188] HRMS for [M+H]+ :Calcd.210.0874; Found210.0953.

[0189] Example 11 Synthesis of Eu(ACAC)3(PhenSO) molecule

[0190] The synthesis method is as follows:

[0191]

[0192] Acetylacetone (0.3 g, 3 mmol, 3 eq) and PhenSO4 (0.48 g, 1 mmol, 1 eq) were added to 10 mL of ethanol in a round-bottom flask and stirred at room temperature. Then, NaOH aqueous solution (3.0 M, 3 eq) was added to adjust the pH of the solution. Next, EuCl3·6H2O (0.37 g, 1 mmol, 1 eq) was dissolved in 2 mL of deionized water and added to the above solution. The mixture was stirred continuously at 75 °C for 4 hours. After removing the solvent under reduced pressure, the crude product was collected and washed with ethanol and deionized water. The purified product was dried under vacuum to give a yellow solid.

[0193] The elemental analysis results of the above products are as follows: C, 58.44; H, 5.01; N, 4.54; found: C, 58.23; H, 5.03; N, 4.41.

[0194] Example 12 Synthesis of Eu(TTA)3(PhenSO) molecule

[0195] The synthesis method is as follows:

[0196]

[0197] Trifluorothiophene acetone (0.67 g, 3 mmol, 3 eq) and PhenSO4 (0.48 g, 1 mmol, 1 eq) were added to 10 mL of ethanol in a round-bottom flask and stirred at room temperature. Then, NaOH aqueous solution (3.0 M, 3 eq) was added to adjust the pH of the solution. Next, EuCl3·6H2O (0.37 g, 1 mmol, 1 eq) was dissolved in 2 mL of deionized water and added to the above solution. The mixture was stirred continuously at 75 °C for 4 hours. After removing the solvent under reduced pressure, the crude product was collected and washed with ethanol and deionized water. The purified product was dried under vacuum to obtain a yellow solid, namely the complex Eu(TTA)3PhenSO4 (EuTPS).

[0198] The elemental analysis results of the above products are as follows: C, 50.24; H, 2.89; N, 3.25; found: C, 50.15; H, 3.19; N, 3.14.

[0199] Example 13 Synthesis of EuTPS-N molecule

[0200] The chemical structural formula of the EuTPS-N molecule is as follows:

[0201]

[0202] EuTPS (0.5 mg), PdPc (4.8 μg), and a mixture of polystyrene-grafted polyethylene oxide (PS-PEO) (20 mg) and 1 mL of THF were added to a 10 mL round-bottom flask. Then, 2 mL of ultrapure water was rapidly injected into the solution. The mixture was stirred for 20 minutes, and the THF was removed under vacuum using a rotary evaporator. Finally, the solution was filtered through a 0.22 μm membrane filter to obtain EuTPS-N, which was stored at 4 °C.

[0203] Luminescent performance testing and performance comparison

[0204] To compare the afterglow emission spectra of the obtained long-afterglow EuTPS system and the conventional long-afterglow system Eu(TTA)3Phen&SO (referred to as EuTP&SO), the emission spectra of EuTP&SO were tested. Figure 2 The following are the spectra of the EuTPS and EuTP&SO systems in dichloromethane (DCM) solution, with reference to... Figure 2 The inset shows the corresponding long afterglow intensities of the two long afterglow systems. As can be seen from the figure, the afterglow emission spectra of both systems show the characteristic emission of Eu(III) at 612 nm. The afterglow intensity of EuTPS is significantly improved by 26 times compared with EuTP&SO, thus proving that the afterglow intensity is greatly improved after the buffer unit and the emitter form a coordination effect. Figure 3 The afterglow lifetime decay curves of the two afterglow systems in DCM solution were obtained. The afterglow lifetimes were measured, and lifetimes of 0.8 s and 1 s were obtained, respectively. Figure 4 Afterglow photographs taken after the laser was turned off showed that the EuTPS system had extremely high afterglow intensity, with its brightness still higher than the initial value of the EuTP&SO system after 6 seconds of decay. Meanwhile, the brightness values ​​of EuTPS, EuTP&SO, and EuTP were evaluated, with reference to... Figure 5 The concentrations of SO, EuTP, and EuTPS used were all 5 × 10⁻⁶. -5 mol L -1 The concentration of PdPc is 5 × 10⁻⁶. -7 mol L -1 According to the definition given in the IUPAC Gold Book and using classic testing methods, the EuTPS long-persistence system achieves a brightness of up to 90568 MHz. -1 cm -1This is 22 times brighter than the EuTP&SO long-afterglow system, and even twice as bright as EuTP.

[0205] To determine the contribution to the long-afterglow quantum yield, the afterglow emission characteristics of PCU molecules were studied without introducing any emitter. Afterglow emission spectra of PhenSO and SO were collected using PdPc as a photosensitizer. (Refer to...) Figure 6 Compared with conventional PCU molecule SO, PhenSO has a weaker afterglow intensity at 385 nm (A band) and a new emission peak at 490 nm (B band).

[0206] To determine the afterglow emission peak of PCU, the photooxidation product of PCU (PCU') was the most reasonable choice. Therefore, PhenSO' and SO' were obtained by complete photooxidation and further purification to study the luminescence properties. Simultaneously, two moieties, PhenSO', methyl 4-(1,10-phenanthroline-5-yl)benzoate (PMB) and ethyl 4-(dimethylamino)benzothioate S-ethyl ester (DBT), were synthesized to specify the emission bands, and the fluorescence spectra of DBT, PMB, SO', and PhenSO' were obtained. (Refer to...) Figure 7 The fluorescence spectra of SO' and PhenSO' show that the emission peak at 380 nm matches the A band in the afterglow emission spectra of SO and PhenSO, respectively. Only PhenSO' exhibits a shoulder peak near 490 nm, corresponding to the B band in the afterglow emission spectrum of PhenSO. Furthermore, the A bands in the fluorescence spectra of DBT, SO', and PhenSO' are almost identical, suggesting that the fluorescence of PhenSO' and SO' may originate from the DBT portion.

[0207] To verify the luminescence properties of the TICT state, the fluorescence response to changes in the solvent properties of PhenSO' was measured. First, under essentially constant viscosity control, the response of the TICT state to solvent polarity was investigated. With increasing proportion of ethyl acetate (EA), the polarity of the mixed solvent increased, and correspondingly, the intensity of the B band increased. Specific results can be obtained from... Figure 8 It's very intuitive to see.

[0208] With the polarity essentially unchanged, this example investigated the effect of a mixed solvent of DMF and DMSO on its fluorescence intensity. The results are referenced... Figure 9 As the percentage of dimethyl sulfoxide (DMSO) increases, the viscosity of the mixed solvent increases, and the strength of the B band decreases.

[0209] The above findings indicate that the B-band of PhenSO' is stronger than that of SO' in EA and DBT, suggesting that PhenSO' has enhanced TICT emission. Therefore, it is reasonable that the new PCU (PhenSO) has stronger TICT state afterglow emission than SO.

[0210] Based on the above information, we will continue to study the contribution of PhenSO to TICT emission enhancement during afterglow emission and the energy transfer process in the long afterglow system provided in this embodiment.

[0211] Based on the general luminescence principle of Eu(III) complexes, the luminescence of Eu(III) is usually achieved through the antenna effect of the diketone ligand, see [link to relevant documentation]. Figure 10 The sensitizing effect of TTA can be found in [reference needed]. Figure 11 , Figure 11 The UV absorption of TTA and the emission spectra of the two buffer unit molecules (SO and PhenSO) at 390 nm partially overlap, indicating the possibility of energy transfer from the A band of PCU to TTA, which exists in the EuTP&SO and EuTPS systems. Due to the newly emerging emission peak (B band, i.e. TICT emission) in PhenSO, it is speculated that the TICT state can provide additional accessibility to sensitized Eu(III).

[0212] To further consider the effect of energy transfer distance, the quantum yields of the EuTP and PhenSO systems were compared, where the energy transfer from PCU to the Eu complex was entirely intermolecular. See [link to relevant documentation]. Figure 12 The figures show the afterglow quantum yields of three afterglow systems (from left to right: EuTP&SO, EuTP&PhenSO, and EuTPS) in DCM solution, with insets showing the corresponding afterglow photographs. The results indicate that EuTP&PhenSO exhibits a brighter afterglow compared to EuTP&SO. If energy transfer occurs only from the A-band, the afterglow intensity of the EuTP&SO system is unlikely to be brighter due to the weaker A-band of PhenSO compared to SO. Therefore, the TICT state plays a crucial role in improving the quantum yield of the EuTP and PhenSO systems, attributed to the compatibility of the TICT state with the lowest excited state of Eu(III). Based on the more favorable buffer unit, PhenSO, the shortened energy transfer distance further improves the quantum yield. These results reveal the synergistic effect of improved PCU molecules and intramolecular energy transfer.

[0213] Explanation of principles

[0214] Based on the above results, an energy transfer mechanism involving the entire afterglow emission process is proposed, see [link to relevant documentation]. Figure 13 Under the excitation of a 730nm laser, the triplet excited state of PdPc transfers energy to O2 to generate... 1O2 reacts with PCU molecules in a [2+2] cycloaddition reaction to produce an epoxy structure of PCU (PCU-O). The PCU-O molecule undergoes a ring-opening reaction during chemical excitation to form an excited state of the photo-oxidized product (PCU'). The excited state of PCU' is then deactivated by transferring its energy to the emitter, where energy from the TICT state (S1) is transferred to Eu(III), denoted as path A. Correspondingly, path B explains TTA sensitization based on the antenna effect following the energy transfer from S2 to TTA. Finally, the energy from both paths sensitizes Eu(III) to achieve bright afterglow luminescence.

[0215] To further demonstrate the important role of pathway A, the diketone ligand was converted to acetylacetone (acac). Due to the high S1 energy level, see [link to relevant documentation]. Figure 14 The UV absorption of acac and the emission spectra of the two buffer unit molecules (S0 and PhenSO) hardly overlap, thus blocking energy transfer pathway B. Synthesize Eu(acac)3PhenSO to construct the EuAPS system (PdPc&EuAPS), see [link to documentation]. Figure 15 Unexpectedly, it exhibits bright afterglow luminescence at 612 nm. See also Figure 15 Compared to the EUAP&SO long afterglow system, its intensity is increased by 196 times, which is attributed to the main contribution of energy transfer from the TICT state, i.e., pathway A.

[0216] To further demonstrate that energy from PhenSO is transferred to Eu(III), the intrinsic luminescence quantum yields of Eu(III) using TTA and acac as ligands were compared, respectively. 1,10-phenanthroline was used as a ligand to simplify the study. According to Equation 1,

[0217]

[0218] Assume Eu(III) 5 D0→ 7 The radiative transition rates (δ) of the F2 transitions are the same, therefore the ratio of δ is equivalent to the ratio of the measured lifetimes (δ). See also Figure 16 and Figure 17 Direct excitation of Eu(III) in both complexes was performed using 580 nm excitation light, yielding two emission lifetimes of 703 μs and 653 μs at 612 nm. These similar values ​​indicate that the ratio of Eu(III) in the two complexes is approximately equal, at 1.08. Furthermore, according to Equation 2,

[0219] k r φ int τ obs τ obs , TTA τobs，acac φ int

[0220] φ ovl =φ int ×η sens

[0221] See Figure 10 The total luminescence quantum yield (δ) of the complex is equal to the product of the ligand sensitization efficiencies (δ). Experimental results show that the contents of EuTP and EUAP are 70% and 5%, respectively, indicating a 20-fold difference between TTA and acac. However, the difference in afterglow luminescence quantum yield between the EuTPS and EuAPS systems is only about 3-fold. For the EuTPS and EuAPS systems, under the condition of the same PdPc absorption energy, the difference in afterglow luminescence quantum yield should be considered. Therefore, the bright afterglow luminescence of the EuAPS system is mainly attributed to the sensitization of the TICT state in PhenSO (pathway A). In other words, in the newly established afterglow system, the TICT state of PhenSO can sensitize Eu(III) to produce bright afterglow luminescence, rather than first transferring energy to the diketone ligand. It is worth noting that, see [link to relevant documentation]. Figure 18 In conventional PA (Eu complex and SO) systems, the afterglow intensity of the acac system is 40 times lower than that of the TTA system, while it increases by 3.5 times in the newly established system. These results demonstrate a significant enhancement of the low quantum yield emitter (Eu(acac)3Phen), involving afterglow luminescence of the same order of magnitude as the high quantum yield emitter (Eu(TTA)3Phen), which is difficult to achieve in PA systems. (See [link to relevant documentation] for details.) Figure 19 .

[0222] Application areas

[0223] Due to the high quantum yield of the EuTPS afterglow system, it is highly advantageous for bioimaging with a high signal-to-background ratio (SBR). EuTPS nanoparticles (EuTPS-N) were prepared via nanoprecipitation through the self-assembly of PdP / EuTPS and the amphiphilic polymer PS-PEO in optimized proportions of different components. See [link to documentation]. Figure 20 See also Figure 21 Transmission electron microscopy (TEM) images confirmed the presence of spherical and uniformly dispersed nanoparticles, and dynamic light scattering (DLS) results showed that the average diameter of EuTPS-N was 22.6 nm, consistent with the TEM results. See also Figure 22 Under 730 nm laser irradiation, EuTPS-N exhibits a bright red afterglow in aqueous solution. The afterglow spectrum also shows characteristic emission of Eu(III) at 612 nm, similar to the characteristic emission in DCM solution. Some fine structures disappear, which may be due to changes in the solvent environment. Furthermore, see [link to other documentation]. Figure 23The afterglow lifetime of EuTPS-N nanoparticles in aqueous solution is 1.72 s, which is slightly longer than that of EuTPS in DCM solution. (See also...) Figure 23 The afterglow image of EuTPS-N in the centrifuge tube showed a strong signal after the laser was turned off. Therefore, the successful preparation of EuTPS-N opens up possibilities for in vivo luminescent bioimaging.

[0224] In vivo chemiluminescence imaging in live nude mice was further performed using a laboratory-constructed in vivo imaging system equipped with an EMCCD as the signal acquisition device. EuTPS-N (50 μL) was subcutaneously injected into the axilla of anesthetized live mice. See also Figure 25 In 730nm laser (10mWcm) -2 Afterglow images were collected 1 second after irradiation, and the afterglow signal was still detectable several seconds later. EuTPS-N fluorescence signals were also collected in mice under 365nm LED irradiation, and signals from uninjected subcutaneous sites were also collected due to severe reflection and scattering of the excitation light and autofluorescence in live mice. See also Figure 24 According to quantitative results, the signal-to-background ratio (SBR) of the afterglow signal reaches as high as 655 after 1 second of decay, which is nearly 80 times higher than that of fluorescence imaging. Even after several seconds of decay, the SBR of afterglow imaging remains significantly higher than that of fluorescence. The superior imaging performance of EuTPS-N demonstrates the great potential of this afterglow material for bioimaging and further related applications.

[0225] In addition to its applications in the field of biological imaging, the long-persistence system described in this application can also be used in homogeneous detection, immunochromatographic detection, surgical navigation, multidimensional display, information storage and encryption, anti-counterfeiting, and other fields.

[0226] For example, the emission signals of multicolor long-persistence luminescent nanoparticles provide multiple independent wavelength channels, enabling the storage of three-dimensional information on a single-layer recording medium. Simultaneously, information storage based on long-persistence luminescence exhibits a lower noise level than synchronously excited fluorescence modes, facilitating the achievement of optical information storage with a higher signal-to-noise ratio.

[0227] For example, the aforementioned long-afterglow nanoparticles can be dispersed in methanol, ethanol, or water to prepare inks with fluorescent encryption and anti-counterfeiting properties. Near-infrared long-afterglow emission has the advantage of being difficult for the human eye to observe, enabling the design of machine-detected multi-dimensional high-level anti-counterfeiting labels and methods. Compared to traditional fluorescent anti-counterfeiting materials, it is much more difficult to crack, greatly improving the concealment of anti-counterfeiting and the encryption effect of confidential documents. It can be applied to military encryption, document protection, and other national defense construction, as well as to consumer goods and pharmaceuticals, exhibiting high anti-counterfeiting encryption capabilities that are difficult to imitate and replicate.

[0228] For example, the long-persistence system in this application can be widely used in optoelectronic displays, multi-stimulus responsive optical indicators, and encoding, visual reading, and differential response encryption of time-sensitive dual-field information.

[0229] In summary, the long-persistence system provided in this application allows the emitter to combine with the buffer unit through coordination. Based on the TICT state energy, the energy can be transferred to the emitter, thereby shortening the energy transfer path, making energy transfer easier, and resulting in a higher luminescence quantum yield. This system has wide applications in fields such as bioimaging and detection.

[0230] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The solutions disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant parts can be found in the method section.

[0231] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A photochemical long afterglow system, characterized in that, The long afterglow system includes: A) At least one photosensitizer; B) At least one emitter; C) At least one cache unit; The buffer unit and the emitter form a complex through coordination; the chemical formula of the complex is L2ML1, where M is the central atom of the complex, L1 is the buffer unit, L2 is the diketone ligand of the emitter, L2M is the emitter, and the number of ligands in L1 and L2 can be adjusted according to the central atom of the complex; the central atom of the complex is Eu. The cache unit comprises the chemical structure of formula (I): （I）; In equation (I), X represents S; n represents 1; and the structural formula of R is: ； The structural formula of the diketone ligand is: 。 2. The photochemical long afterglow system according to claim 1, characterized in that, The molar ratio of the complex to the photosensitizer is 1:10~10000.

3. The photochemical long afterglow system according to claim 1, characterized in that, The photosensitizer is selected from one or more of the following: polymethyl cyanine dyes, porphyrin and phthalocyanine dyes and their complexes, methylene blue compounds, phycoerythrin, bamboo red pigment, benzophenone compounds, organometallic frameworks, quantum dots, graphene, carbon nanotubes, titanium dioxide semiconductors, and copolymers of the above substances.

4. The photochemical long afterglow system according to claim 3, characterized in that, The photosensitizer is selected from one or more of the following chemical structures: ; ; 。 5. The photochemical long afterglow system according to claim 1, characterized in that, The long afterglow system also includes a carrier medium for dissolving, dispersing or adsorbing components A, B, and C; the carrier medium is one of an organic solution or an aqueous medium.

6. The photochemical long afterglow system according to claim 5, characterized in that, The organic solution includes aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, alcohols, esters, and ketones.

7. The photochemical long afterglow system according to claim 5, characterized in that, The aqueous medium includes nano-dispersions, microsphere dispersions, and nano-micelle dispersions.

8. The photochemical long afterglow system according to claim 1, characterized in that, The long afterglow system exists in one of the following forms: nanomaterials, thin films, gels, or biological media.

9. The application of a photochemical long afterglow system according to any one of claims 1-8, characterized in that, Used for multi-dimensional display, information storage and encryption, and anti-counterfeiting.

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