Long-persistent compounds, systems, and methods of preparation and use based on covalent bonding

Abstract

This invention provides a long-afterglow compound, system, preparation method, and application based on covalent bond coupling. The long-afterglow compound absorbs photons and transfers the absorbed photon energy within the molecule, undergoing a photochemical reaction that releases the energy as light, thus achieving afterglow luminescence. The structure of the long-afterglow compound is shown in Formula I, where X is selected from O or S; R is selected from a photosensitizer; and n is 1–15. The long-afterglow system includes a carrier medium and a long-afterglow compound, wherein the carrier medium is used to dissolve, disperse, or adsorb the long-afterglow compound. This invention can achieve near-infrared luminescence at 660 nm and 718 nm, and can be applied in fields such as bioimaging, immune detection, cell tracking, biosensing, and information encryption.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a long afterglow compound based on covalent coupling, its system, preparation method, and applications. Background Technology

[0002] Afterglow is a natural phenomenon that continues to emit light even after the excitation light is turned off. This phenomenon has wide applications in military, anti-counterfeiting, encryption, display, and information storage fields. Currently, afterglow materials are mainly divided into organic and inorganic afterglow materials. Among them, inorganic afterglow materials are mainly prepared through solid-solid reactions, solvothermal methods, etc., and their morphology is difficult to control. In practical applications, batch control of nanoscale preparation is difficult. The luminescence of organic afterglow materials depends on the medium in which they exist. For example, organic afterglow materials usually require a rigid environment such as MOF (metal-organic framework), polymers, and host-guest interactions, thus requiring nanomaterials as carriers.

[0003] Recently, a novel long-afterglow system based on photochemical reactions has attracted widespread attention. This photochemical long-afterglow system typically consists of three parts: 1) a system capable of generating singlet oxygen (…). 1 O2) photosensitizer; 2) with 1 3) A storage unit that reacts with O2 and releases energy; 4) An emitter that can receive energy released by the storage unit and emit photons. Since all three components in the photochemical long afterglow system are organic molecules, nanospheres containing photochemical long afterglow materials with good morphology can be prepared by means of swelling method, and have good adjustability in terms of emission wavelength and luminescence lifetime.

[0004] However, existing photochemical long-persistence systems are composed of three components. Within the confined space of the nanosphere, the distribution of these components may be uneven; that is, the photosensitizer, storage unit, and emitter may be randomly arranged rather than sequentially adjacent. This can lead to the photosensitizer being concentrated in one area, resulting in a longer path for singlet oxygen generated by the photosensitizer to be transferred to the storage unit. Some singlet oxygen may fail to transfer, causing energy loss. Therefore, energy transfer between the three components within the nanosphere is relatively inefficient, directly leading to low quantum efficiency. Furthermore, current photochemical long-persistence systems often suffer from problems such as unsatisfactory signal intensity and complex composition. Therefore, improving the energy transfer efficiency between different components within the nanosphere has become a crucial problem urgently needing to be solved in the field of long-persistence luminescence. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the purpose of this invention is to provide a long afterglow compound based on covalent coupling, a system, a preparation method and an application.

[0006] Since the luminescence of organic afterglow materials depends on the medium in which they exist, nanomaterials are generally required as carriers. Nanospheres are an excellent carrier for photochemical long afterglow materials. However, within the confined space of nanospheres, the energy transfer between the three components in the photochemical long afterglow system is relatively inefficient, and the low energy transfer efficiency leads to a low quantum efficiency.

[0007] Therefore, this invention provides a novel approach that covalently couples the sensitizer, buffer, and luminescent agent, transforming the traditional energy transfer between the three components into intramolecular energy transfer. By bringing the sensitizer and buffer closer together through covalent bonding, singlet oxygen generated during light exposure can react more quickly with the buffer, releasing energy and achieving highly efficient luminescence. This improves energy transfer efficiency and, consequently, luminescence quantum efficiency. The photochemical long-afterglow molecule designed based on this approach can achieve near-infrared luminescence at 660 nm and 718 nm. This has significant implications for fields such as bioimaging and immunoassay.

[0008] According to one aspect of the present invention, a long afterglow compound based on covalent coupling is provided, wherein the long afterglow compound absorbs photons and transfers the absorbed photon energy within the molecule, a photochemical reaction occurs within the molecule and the energy is released in the form of light energy, thereby achieving afterglow luminescence;

[0009] The structure of the long afterglow compound is as shown in Formula I:

[0010]

[0011] In Formula I, X is selected from O or S; R is selected from one of the photosensitizers; and n is 1 to 15.

[0012] When a light source illuminates the aforementioned organic long-afterglow compound, the R group in the organic long-afterglow molecule structure, i.e., the photosensitizer, absorbs the light and transfers energy to oxygen, thereby generating singlet oxygen. This singlet oxygen reacts with the structural parts outside the R group of the organic long-afterglow molecule structure (which can be understood as storage units). As the storage units release energy and transfer it to structure R (which can be understood as the emitter part), afterglow luminescence is achieved. When the energy of the singlet oxygen on structure R is transferred to the structural parts outside R, the double bond between O and X in formula (I) breaks, and an oxidative addition reaction occurs on the carbon atoms connected to O and X, reforming the C=O double bond. The principle is as follows:

[0013]

[0014] In this invention, the structure in formula (Ⅰ) can act as both a photosensitizer and a luminescent agent. The photosensitizer and the buffer are covalently linked, allowing the singlet oxygen generated after illumination to react more quickly with the buffer. Of course, if it is necessary to distinguish between the photosensitizer and the luminescent agent in certain situations, this can be understood as the photosensitizer, buffer, and luminescent agent forming a new molecule through covalent bonding.

[0015] The long-afterglow compound provided by this invention, covalently coupled, combines three components into a single molecule, simultaneously possessing three functions: absorbing photons and transferring the absorbed photon energy to the reactants, storing photochemical energy, and emitting energy as light. Through molecular design, a single long-afterglow molecule simultaneously functions as a photosensitizer, storage unit, and emitter (light emitter). Those skilled in the art will understand that for molecules with similar composition and structure, the intramolecular forces of covalently coupled molecules are stronger than the intermolecular forces of three independent molecules. Therefore, the distance between covalently coupled long-afterglow systems is shorter, resulting in a shorter singlet oxygen transfer path, less singlet oxygen loss, and higher energy transfer efficiency. The photochemical long-afterglow molecule designed in this way can achieve near-infrared emission at 660 nm and 718 nm.

[0016] Optionally, the photosensitizer is selected from at least one 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, polyfluorene compounds, coumarin compounds, naphthylimide compounds, triphenylene or higher phenylene compounds, halogenated compounds, pyrazoline compounds, triphenylamine compounds, carbazole compounds, rhodamine compounds, fluorescein compounds, fluoroboron dipyrrole compounds, green fluorescent protein, bimane compounds, perovskite luminescent nanomaterials, TADF compounds, and derivatives and copolymers of the above substances.

[0017] Polymethylcyanine dyes often use various heterocyclic compounds such as indole, pyridine, quinoline, thiazole, and pyrrole as terminal groups. The molecule contains a conjugated chain composed of methylene groups (also called methinel groups). Heterocyclic, aromatic, or cycloalkenyl compounds are attached to the ends or middle of the conjugated chain, forming a large conjugated system. The hydrogen atoms within the molecule can be replaced by a certain number of various substituents. The structural formula is as follows:

[0018]

[0019] Where n = 1, 2, and 3 represent trimethylamine, pentamethylamine, and heptamethylenetetramine dyes, respectively.

[0020] Preferably, the polymethyl cyanine dye has the following structure:

[0021]

[0022] Preferably, porphyrin dyes and their complexes are selected from any one of the following compounds:

[0023]

[0024]

[0025] Preferably, phthalocyanine dyes and their complexes are selected from any one of the following compounds:

[0026]

[0027] In the structural formulas of the photosensitizer compounds shown above, X represents halogens such as F, Cl, Br, and I; and M represents metal elements such as Mg, Fe, Co, Ni, Cu, Zn, Pd, Pt, Ln, Ce, Pr, Nd, Pm, Sm, Eu, Cd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0028] Various substituents R such as R 1-24 It represents H, hydroxyl, carboxyl, amino, mercapto, ester, aldehyde, nitro, sulfonic acid, halogen, or having 1-50, preferably 1-24, such as alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkoxy, alkylamino, or combinations thereof having 2-14 carbon atoms.

[0029] Preferably, the above-mentioned group R is such as R 1-24 Each is independently selected from methoxy, ethoxy, dimethylamino, diethylamino, methyl, ethyl, propyl, butyl, tert-butyl, phenyl, or combinations thereof.

[0030] Transition metal complexes that can be used as photosensitizers are preferably complexes of porphyrin and phthalocyanine dyes as shown above.

[0031] Alternatively, quantum dot materials include, for example, graphene quantum dots, carbon quantum dots, and heavy metal quantum dots.

[0032] Heavy metal quantum dots include any one of Ag2S, CdS, CdSe, PbS, CuInS, CuInSe, CuInGaS, CuInGaSe, and InP quantum dots. Preferably, they are encapsulated in a shell to form a core-shell structure, and the shell is any one or more of Ag2S, CdS, CdSe, PbS, CuInS, CuInSe, CuInGaS, CuInGaSe, and ZnS.

[0033] Preferably, the quantum dots are modified with surface ligands, such as oleic acid, oleylamine, octadecene, octadecylamine, n-dodecyl mercaptan, and combinations thereof. In some more advantageous cases, the ligands on the quantum dot surface are partially replaced with molecular structures containing triplet states through ligand exchange strategies, such as carboxyanthracene, carboxy-3-tetraphenyl, carboxy-5-pentaphenyl, aminoanthracene, amino-3-tetraphenyl, amino-5-pentaphenyl, mercaptoanthracene, mercapto-3-tetraphenyl, mercapto-5-pentaphenyl, etc.

[0034] Preferably, the fluoroboron dipyrrole compound (BODIPY) is selected from any one of the following compounds:

[0035]

[0036]

[0037] Preferably, the benzene compounds are selected from any one of the following compounds:

[0038]

[0039] In the structural formulas of the luminescent compounds shown above, n = an integer greater than or equal to 0, such as 0, 1, 2, and 3; each substituent R is as follows: 1-16 It represents H, hydroxyl, carboxyl, amino, mercapto, ester, aldehyde, nitro, sulfonic acid, halogen, or alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkoxy, alkylamino, or combinations thereof having 1-50, preferably 1-24, such as 2-14 carbon atoms.

[0040] Preferably, the group R is such as R 1-16 It is selected from methoxy, ethoxy, dimethylamino, diethylamino, methyl, ethyl, propyl, butyl, tert-butyl, phenyl; or combinations thereof.

[0041] Preferably, the methylene blue compound is methylene blue, with the following structure:

[0042]

[0043] Preferably, the structure of bamboo red mycin is as follows:

[0044] Preferably, the structure of xylene ketone compounds is as follows:

[0045]

[0046] Preferably, the quantum dot structure is as follows:

[0047]

[0048] Preferably, the organometallic framework structure is as follows:

[0049]

[0050] More preferably, the photosensitizer is selected from any one of the following structures:

[0051]

[0052] These photosensitizers are relatively easy to synthesize and facilitate the identification of buffer content; porphyrins have a wide absorption range, covering most of the ultraviolet-visible bands, and also have sufficient singlet oxygen yield, enabling them to emit near-infrared light.

[0053] The metal atom at the center of the photosensitizer can be adjusted, wherein the central atom M in the structure is selected from any one of Mg, Fe, Co, Ni, Cu, Zn, Pd, Pt, Ln, Ce, Pr, Nd, Pm, Sm, Eu, Cd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

[0054] Optionally, the photosensitizer molecule does not include metal atoms, and the structure of the photosensitizer is as follows:

[0055]

[0056] Preferably, the long afterglow compound is any one of the following compounds:

[0057]

[0058] In long-afterglow compounds with the above structure, the connection between the photosensitizer and the buffer is relatively simple. Most ultraviolet-visible light can cause it to produce afterglow light, and the afterglow light intensity is very strong. It can produce a large amount of afterglow light on the order of seconds, and its emission is in the near-infrared region.

[0059] According to a second aspect of the present invention, a long afterglow system based on covalent coupling is provided, the system comprising a support medium and the aforementioned long afterglow compound based on covalent coupling, wherein the support medium is used to dissolve, disperse or adsorb the long afterglow compound.

[0060] In this invention, the term "carrier medium" refers to a substance used to adsorb the long afterglow system as described above, and which helps to form a stable medium loaded with the above components.

[0061] Optionally, the carrier medium is an organic solution or an aqueous medium.

[0062] Preferably, the organic solution comprises any one of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, alcohols, esters, and ketones.

[0063] Aromatic hydrocarbons, also known as aromatic hydrocarbons, generally consist of one or more benzene rings with specific structures, and have the general structural formula C1. n H 2n-6 Aliphatic hydrocarbons are hydrocarbons that possess the basic properties of aliphatic compounds. Also known as aliphatic hydrocarbons, their molecules contain only carbon and hydrogen elements, with carbon atoms linked together in chains or rings. These carbon atoms are connected by covalent bonds to form chain or ring-like carbon skeletons. Alicyclic compounds are a class of carbocyclic compounds with properties similar to aliphatic compounds. Halogenated hydrocarbons include fluorinated hydrocarbons, chlorinated hydrocarbons, bromine hydrocarbons, and iodocarbons. Alcohols are compounds containing hydroxyl groups bonded to carbon atoms on the side chains of hydrocarbon groups or benzene rings. Esters are organic compounds formed by the reaction of acids (carboxylic acids or inorganic oxyacids) with alcohols. Ketones are compounds in which a carbonyl group is bonded to two hydrocarbon groups.

[0064] Preferably, the aqueous medium includes any one of nano-dispersion, microsphere dispersion, and nanomicelle dispersion.

[0065] "Nano dispersion" refers to a liquid phase formed by reducing aggregates of various forms of dried nanoparticles into primary particles and stabilizing and uniformly distributing them in a specific liquid medium (such as water or solvent) using various principles, methods, and techniques. Similarly, "microsphere dispersion" refers to the uniform dispersion of microspheres in a solvent by placing microspheres in a specific medium and using methods such as ultrasound, while "nanomial dispersion" disperses nanomicelles.

[0066] Optionally, the long afterglow system can exist in any of the following forms: nanomaterials, thin films, gels, and biological media.

[0067] According to a third aspect of the present invention, a method for preparing the above-described long afterglow system based on covalent coupling is provided, the method comprising:

[0068] The storage unit was halogenated and then a functional group was introduced through a Suzuki coupling reaction to form a compound;

[0069] The resulting compound is chemically reacted with a photosensitizer to obtain a long-afterglow compound based on covalent bond coupling, wherein the long-afterglow compound is a molecule with a single component;

[0070] The long-afterglow compound was dissolved in a carrier medium and purified by stirring to obtain photochemical long-afterglow systems with different nano-morphologies.

[0071] "Halogenation" includes fluorination, chlorination, bromination, and iodination; "Suzuki coupling reaction" is a common and effective method for synthesizing carbon-carbon bonded compounds by coupling organoboron compounds with organohalogen compounds under palladium catalysis.

[0072] Storage units can also be understood as caches, including any of the following structures:

[0073]

[0074] The specific reaction process can be seen as follows:

[0075]

[0076] Of course, those skilled in the art will understand that, under normal circumstances, photosensitizers can act as both sensitizers and luminescent agents. In order to improve the luminescence effect, different photosensitizers and luminescent agents may be selected. In this case, the original storage unit can form a large conjugated system with the sensitizer and the luminescent agent, and therefore can also be considered as a single component.

[0077] The carrier medium mentioned in the above reaction is either an organic solution or an aqueous medium. Preferably, the aqueous medium includes nano-dispersions, microsphere dispersions, and nanomicelle dispersions.

[0078] According to a fourth aspect of the present invention, an application is provided for the long-persistence compound based on covalent coupling as described above or the long-persistence system based on covalent coupling as described above, specifically, in the fields of bioimaging, drug delivery, immunodiagnosis, and photodynamic therapy.

[0079] The term "covalent coupling" in this invention generally refers to the covalent attachment of one molecule or compound or a group on a molecule to another molecule or a group on a molecule under certain conditions to produce a complex or compound consisting of two molecules linked together. The two molecules that are covalently coupled form a conjugated system or have a conjugation effect. In some contexts, it can also be understood as covalent bonding, covalent coupling, or molecular conjugation. The molecule after covalent coupling can be regarded as a single component.

[0080] In this invention, the terms "long-afterglow molecule" and "long-afterglow compound" have the same meaning. They are relatively stable core molecules in a long-afterglow system that can exist independently and can promote the luminescence properties of the long-afterglow system. They can be small molecules, supramolecular molecules, or polymers. It can be understood that the long-afterglow system is a mixture or a composition, while the long-afterglow molecule is a pure substance, that is, the long-afterglow molecule is a single component.

[0081] The term "photosensitizer" in this invention generally refers to a substance that can absorb and capture light energy from natural or artificial light sources. In some cases, as those skilled in the art will know, conventional long-afterglow systems also contain luminescent agents or emitters. The compositions of this invention do not strictly distinguish between photosensitizers and luminescent agents. For example, in advantageous embodiments, compounds that structurally possess both light-absorbing and light-emitting groups, thus allowing the same molecule to perform both functions, may be used. In other advantageous embodiments, the light-absorbing group may act as the photosensitizer, and the luminescent group as the luminescent agent. Thus, this invention covalently couples the photosensitizer, buffer, and luminescent agent together to form a new conjugated molecule.

[0082] In some contexts, the term "long-afterglow system" in this invention can also be understood as "long-afterglow luminescent system," which includes, for example, sensitizers or photosensitizers, storage units or buffers, luminescent agents or emitters, other additives, carrier media, etc. In other words, a long-afterglow system is all the substances or solutions required between light energy input and light energy output.

[0083] The long-persistence system provided by this invention comprises the aforementioned long-persistence molecules coupled by covalent bonds. Unlike the original three independent components—photosensitizer, storage unit, and emitter—this system does not contain multiple components. Energy transfer occurs intramolecularly within the nanospheres, without intermolecular transfer. Therefore, the arrangement and distribution of molecules do not affect the transfer of singlet oxygen, and being a single molecule, there is essentially no issue of molecular arrangement and combination. This improves energy transfer efficiency and luminescence quantum efficiency from multiple angles. The photochemical long-persistence molecule designed based on this method can achieve near-infrared emission at 660 nm and 718 nm. This has significant implications for fields such as bioimaging and immunoassay.

[0084] Since the molecular arrangement does not affect the transfer of singlet oxygen, changes in the surrounding environment have little impact on the luminescence of the long-persistence system, enabling its use in various environments. When the long-persistence system provided in this invention is adsorbed onto nanospheres, these nanospheres exhibit excellent dispersibility in water. Therefore, the long-persistence system provided in this invention has a wide range of applications, including bioimaging, biosensing, drug delivery, immunodiagnosis, immunodetection, cell tracking, surgical navigation, photodynamic therapy, multidimensional display, information storage and encryption, and anti-counterfeiting.

[0085] Furthermore, since the long-persistence system provided by this invention includes long-persistence molecules coupled by covalent bonds, and through reasonable molecular design, the three-component photochemical long-persistence system is transformed into a single-component system. Therefore, there is no problem with the distribution and arrangement of organic molecules in the nanospheres. In this way, the energy transfer efficiency between the components of the photochemical long-persistence system inside the nanospheres is improved, thereby improving the luminescence quantum efficiency.

[0086] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0087] This invention, through rational molecular design, transforms a three-component photochemical long-afterglow system into a single-component system, forming long-afterglow molecules coupled by covalent bonds. Because the distance between the covalently coupled long-afterglow molecules is shorter, the path for singlet oxygen transfer is shorter, resulting in less singlet oxygen loss and thus improving energy transfer efficiency. This invention enables near-infrared emission at 660 nm and 718 nm.

[0088] The long-persistence system provided by this invention comprises covalently coupled long-persistence molecules. It does not have multiple components; energy transfer occurs intramolecularly within the nanospheres, without intermolecular transfer. Therefore, there are no issues regarding the distribution and arrangement of organic molecules within the nanospheres, and the molecular arrangement does not affect the transfer of singlet oxygen, thereby further improving energy transfer efficiency and luminescence quantum efficiency. The long-persistence molecules and system of this invention can be applied in fields such as bioimaging, biosensing, drug delivery, immunodiagnosis, immunodetection, surgical navigation, photodynamic therapy, multidimensional display, information storage and encryption, and anti-counterfeiting. Attached Figure Description

[0089] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0090] Figure 1 This is a schematic diagram comparing the working principles of the long-persistence system based on covalent coupling in this invention embodiment with those of the photochemical long-persistence system in the prior art;

[0091] Figure 2 The 1H NMR spectrum of compound 1 in Example 1 of this invention (…) 1 H NMR spectrum;

[0092] Figure 3 The carbon NMR spectrum of compound 1 in Example 1 of this invention ( 13 C NMR spectrum;

[0093] Figure 4 This is the mass spectrum of compound 5 in Example 1 of the present invention;

[0094] Figure 5 This is the mass spectrum of the oxidation product of compound 5 in Example 1 of the present invention;

[0095] Figure 6 The fluorescence emission spectrum of the TPP-Ph3NSO molecule in Example 1 of this invention;

[0096] Figure 7 The fluorescence absorption spectrum of the TPP-Ph3NSO molecule in Example 1 of this invention;

[0097] Figure 8 This is the afterglow spectrum of TPP-Ph3NSO molecules in DCM solution in Example 1 of this invention;

[0098] Figure 9 This is the afterglow spectrum of the two mixed components TPP+Ph3NSO in DCM solution in Comparative Example 1 of this invention;

[0099] Figure 10 This is the afterglow decay curve of TPP-Ph3NSO molecules in DCM solution in Example 1 of the present invention;

[0100] Figure 11 This is a morphology image of the TPP-Ph3NSO molecule after nanostructuring using PS microspheres in Example 6 of the present invention.

[0101] Figure 12 This is a particle size distribution diagram of the TPP-Ph3NSO molecules after nano-sizing using PS microspheres in Example 6 of the present invention;

[0102] Figure 13 The fluorescence spectrum of the TPP+Ph3NSO system in Comparative Example 2 of this invention after being nano-sized using PS microspheres in water;

[0103] Figure 14 The fluorescence spectrum of TPP-Ph3NSO molecules in water after being nano-sized using PS microspheres in Example 6 of this invention;

[0104] Figure 15 The afterglow spectrum in water after the TPP-Ph3NSO molecules were nano-sized using PS microspheres in Example 6 of this invention;

[0105] Figure 16 The afterglow spectrum in water of the TPP+Ph3NSO system in Comparative Example 2 of this invention after nano-sizing using PS microspheres;

[0106] Figure 17 The afterglow decay curve in water of TPP-Ph3NSO molecules and TPP+Ph3NSO system after being nano-sized using PS microspheres in Example 6 of this invention;

[0107] Figure 18The afterglow decay curve in water of the TPP+Ph3NSO system in Comparative Example 2 of this invention after nano-sizing with PS microspheres. Detailed Implementation

[0108] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0109] To illustrate the differences between the design concept of this invention and the prior art, see [link to relevant documentation]. Figure 1 Taking tetraphenylporphyrin and Ph3NSO(4-(2-(4-phenyl)-5,6-dihydro-1,4-oxothiacyclohexadienyl)-N,N-diphenylaniline) molecules as examples, the existing photochemical long afterglow system mainly includes a photosensitizer, a storage unit, and a luminescent agent (or emitter). The main working principle is that the photosensitizer absorbs photons and transfers light energy to oxygen, turning oxygen into singlet oxygen. The singlet oxygen transfers energy to the storage unit for temporary storage, and then releases it through the luminescent agent or emitter. In this way, the energy transfer involves three independent molecules. Figure 1 Since tetraphenylporphyrin can act as both a photosensitizer and a luminescent agent, the traditional method involves tetraphenylporphyrin absorbing photons and transferring energy to the buffer molecule Ph3NSO. The energy is then transferred back to the tetraphenylporphyrin molecule via Ph3NSO, resulting in luminescence. This energy transfer occurs between the tetraphenylporphyrin and Ph3NSO molecules, and the distance between them directly determines the energy transfer distance of singlet oxygen. A longer energy transfer path leads to greater energy loss and lower energy transfer efficiency. Figure 1 As shown, tetraphenylporphyrin and the buffer Ph3NSO molecules are covalently coupled, forming a single molecule. This transforms the traditional intermolecular energy transfer into intramolecular transfer, thus shortening the energy transfer distance and making the energy transfer more efficient. Therefore, by designing a multi-component photosensitizer, buffer, and luminescent agent within a single molecule, highly efficient energy transfer can be achieved. Specifically, under light irradiation, the sensitizer absorbs energy and transfers it to O2 to generate... 1 O2 is highly reactive. 1 O2 can react with the double bonds of the buffer before decaying. Therefore, it achieves... 1 The system efficiently utilizes O2. Furthermore, after the double bonds in the buffer break and before energy decays, it transfers energy to the luminescent body, enabling it to emit light and maximizing energy utilization.

[0110] The technical solution of the present invention will be described in more detail below with reference to examples and comparative examples. The synthesis of other compounds in the present invention is similar to that in Examples 1 to 5, and the preparation of the long afterglow system is similar to that in Example 6. All of these methods can achieve the same technical effects as the compounds listed in Example 1 and the systems listed in Example 6.

[0111] Example 1

[0112] This embodiment provides a TPP-Ph3NSO long afterglow compound (compound 5), and its preparation process is as follows:

[0113]

[0114] (1) Preparation of compound 1

[0115] 1-(4-bromophenyl)-2-(4-(diphenylamino)phenyl)-2-hydroxyethane-1-one (5 mmol) and toluene (25 mL) were added to a three-necked flask and completely dissolved. 2-Mercaptoethanol (1.05 mL) was then added, followed by the dropwise addition of trimethylchlorosilane (1.27 mL). The mixture was refluxed for 3 h, cooled to room temperature, and saturated sodium bicarbonate solution was added until no more bubbles were generated. The mixture was separated, dried over anhydrous sodium sulfate, and purified by rotary evaporation and column chromatography (petroleum ether / dichloromethane = 6:1) to obtain the target compound in 63% yield.

[0116] The 1H NMR spectrum of compound 1 is shown in [reference needed]. Figure 2 , 1 ¹H NMR (400MHz, Chloroform-d) δ 7.34–7.23 (m, 6H), 7.12–7.03 (m, 10H), 6.97–6.88 (m, 2H), 4.55–4.47 (m, 2H), 3.28–3.18 (m, 2H). See carbon spectra for reference. Figure 3 , 13 C NMR (101MHz, CDCl3) δ147.35,147.00,144.37,135.35,131.75,130.93,130. 54,129.19,124.61,124.45,122.98,122.91,121.16,108.25,65.61,28.05.

[0117] (2) Preparation of compound 2

[0118] Under nitrogen protection, compound 1 (3 mmol) and 20 mL THF were added to a 50 mL round-bottom flask. The mixture was cooled to -78 °C. After maintaining this temperature for 5 min, butyllithium (2.5 M in THF, 4 mmol) was added dropwise to the flask. After the addition was complete, the mixture was stirred at -78 °C for 30 min, then DMF (4 mmol) was added, followed by restoring to room temperature and allowing the reaction to proceed overnight.

[0119] After the reaction was complete, 1 mL of saturated ammonium chloride aqueous solution was slowly added to the flask, followed by extraction with ethyl acetate. The organic phases were combined and washed once with saturated sodium chloride (20 mL). The organic phases were then dried over anhydrous sodium sulfate. The solution was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to give compound 2 (yield 61%).

[0120] (3) Preparation of compound 3

[0121] Compound 2 (3 mmol) and 10 mL of methanol were added to a 25 mL round-bottom flask, and the flask was cooled to 0°C in an ice bath. Then, sodium borohydride (3 mmol) was slowly added to the flask, and the reaction was stirred for 1 h. After the reaction was complete, 1 mL of saturated ammonium chloride aqueous solution was slowly added to the flask, followed by extraction with ethyl acetate. The organic phases were combined, washed once with saturated sodium chloride, and then dried over anhydrous sodium sulfate. The solution was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to give compound 3 (76% yield).

[0122] (4) Preparation of compound 4

[0123] Compound 3 (3 mmol) and 15 mL of dichloromethane were added to a 25 mL round-bottom flask, and the flask was cooled to 0°C in an ice bath. Then, PBr3 (3 mmol) was slowly added to the flask, and the reaction was stirred for 1 h. After the reaction was complete, 5 mL of saturated sodium bicarbonate aqueous solution was added to the flask, followed by extraction with DCM. The organic phases were combined, washed once with saturated sodium chloride, and then dried over anhydrous sodium sulfate. The solution was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to give compound 4 (39% yield).

[0124] (5) Preparation of compound 5

[0125] Under nitrogen protection and in the dark, porphyrin-OH (0.5 mmol), compound 4 (3 mmol), potassium carbonate (6 mmol), and DMF (5 mL) were added sequentially to a 15 mL sealed tube. The mixture was then stirred at 60 °C for 12 h. After the reaction was complete, DMF was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to give compound 5 (yield 14%). The calculated m / z value of compound 5 is 1063.39. (See [reference needed]). Figure 4The actual value is 1063.39.

[0126] (6) Formation of compound 6

[0127] Compound 5 absorbs light energy upon exposure to light, converting oxygen into singlet oxygen. The energy of the singlet oxygen is transferred to the buffer portion within the molecule, where the C=C double bond breaks and oxidizes to form a C=O double bond.

[0128]

[0129] See the mass spectrum of compound 6. Figure 5 The calculated m / z value is 1095.38, and the actual value is also 1095.38. This confirms that compound 5 absorbs energy and transfers it to O2 to produce... 1 O2 is highly reactive. 1 O2 can react with the double bond in compound 5, which acts as a buffer, before decaying.

[0130] Example 2

[0131] The long afterglow compound provided in this embodiment has the following reactants and products (compound 5):

[0132]

[0133] The intermediate process is the same as in Example 1, and the final step, the preparation of compound 5, includes:

[0134] Under nitrogen protection and in the dark, 4-hydroxybenzophenone (0.5 mmol), compound 4 (3 mmol), potassium carbonate (6 mmol), and DMF (5 mL) were added sequentially to a 15 mL sealed tube. The mixture was then stirred at 60 °C for 12 h. After the reaction was complete, DMF was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to obtain the compound.

[0135] Example 3

[0136] The long afterglow compound provided in this embodiment has the following reactants and products (compound 5):

[0137]

[0138] The intermediate process is the same as in Example 1, and the final step, the preparation of compound 5, includes:

[0139] Under nitrogen protection and in the dark, 0.5 mmol of 4-aminobenzophenone, 3 mmol of compound 4, 6 mmol of potassium carbonate, and 5 mL of DMF were added sequentially to a 15 mL sealed tube. The mixture was then stirred at 60 °C for 12 h. After the reaction was complete, DMF was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to obtain the compound.

[0140] Example 4

[0141] The long afterglow compound provided in this embodiment has the following reactants and products (compound 5):

[0142]

[0143] The intermediate process is the same as in Example 1, and the final step, the preparation of compound 5, includes:

[0144] Under nitrogen protection and in the dark, Cy-OH (0.5 mmol), compound 4 (3 mmol), potassium carbonate (6 mmol), and DMF (5 mL) were added sequentially to a 15 mL sealed tube. The mixture was then stirred at 60 °C for 12 h. After the reaction was complete, DMF was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to obtain the compound.

[0145] Example 5

[0146] The long afterglow compound provided in this embodiment has the following reactants and products (compound 5):

[0147]

[0148] The intermediate process is the same as in Example 1, and the final step, the preparation of compound 5, includes:

[0149] Under nitrogen protection and in the dark, methylene blue-NH2 (0.5 mmol), compound 4 (3 mmol), potassium carbonate (6 mmol), and DMF (5 mL) were added sequentially to a 15 mL sealed tube. The mixture was then stirred at 60 °C for 12 h. After the reaction was complete, DMF was removed by vacuum distillation, and the resulting mixture was purified by column chromatography to obtain the compound.

[0150] Comparative Example 1

[0151] To verify that single-component long-afterglow systems are superior to two-component or even three-component long-afterglow systems, Comparative Example 1 was set as a physical mixture of TPP+Ph3NSO long-afterglow materials for characterization and comparison.

[0152] Fluorescence spectroscopy test

[0153] To investigate the optical properties of TPP-Ph3NSO in Example 1, its fluorescence spectrum was first measured. Figure 6 The image shows the fluorescence emission spectrum of TPP-Ph3NSO in dichloromethane (DCM) solution. As can be seen from the image, the fluorescence emission of this molecule is due to the luminescence of tetraphenylporphyrin at 660 nm and 720 nm. (See also...) Figure 7 The fluorescence absorption spectrum of near-infrared light belongs to near-infrared emission and has excellent tissue penetration. Because there is less scattering and absorption when near-infrared light penetrates biological tissues such as skin and fat, and the autofluorescence from the organism is also very low in the near-infrared region, fluorescence imaging in the near-infrared region has a high penetration depth and signal-to-noise ratio in live animal studies, especially photons in the near-infrared second window (NIR-II), which lays the foundation for its application in the field of bioimaging.

[0154] Afterglow luminescence test

[0155] Afterglow luminescence is similar to fluorescence luminescence, emitting light from tetraphenylporphyrin at 660 nm and 720 nm. See [link to related documentation]. Figure 8 Furthermore, the long-afterglow system of a single TPP-Ph3NSO molecule was compared with that of a mixture of TPP and Ph3NSO components, and tests were conducted in a dichloromethane solution. Figure 9 As shown, when the two components are mixed, the emission spectrum is dominated by the blue light of triphenylamine, with red light emitted by the mixed porphyrin; when only one component is used, the emission light is dominated by the light emitted by the porphyrin after energy transfer. The emission peaks are at 660 nm and 718 nm, which are near-infrared emission, exhibiting good tissue penetration depth.

[0156] Luminescence lifetime test

[0157] The afterglow decay curve of TPP-Ph3NSO molecules in DCM solution is shown below. Figure 10 After fitting, it was found that the fitting lifetime was τ = 1.38s. It can be seen that the luminescence decay of TPP-Ph3NSO is a single exponential decay, which is more suitable for the quantitative detection of unknown substances.

[0158] Example 6

[0159] This embodiment provides a long afterglow system, specifically TPP-Ph3NSO molecules coated with nanospheres, and its preparation method includes:

[0160] 0.5 mL of an aqueous dispersion containing blank polystyrene nanoparticles was mixed with 0.3 mL of acetone solution containing TPP-Ph3NSO and sonicated for 10 minutes. The solution was then further mixed for 8 hours using a rotary mixer. After removing unloaded TPP-Ph3NSO and acetone by centrifugation, washing with pure water, and centrifugation, long-afterglow PS (Polystyrene) nanospheres containing monomolecular TPP-Ph3NSO were obtained.

[0161] Comparative Example 2

[0162] This comparative example provides a long afterglow system of TPP+Ph3NSO molecules coated with nanospheres, and its preparation method includes:

[0163] 0.5 mL of an aqueous dispersion containing blank polystyrene nanoparticles was mixed with 0.3 mL of an acetone solution containing TPP and Ph3NSO, and sonicated for 10 minutes. The solution was then further mixed for 8 hours using a rotary mixer. After removing unloaded TPP+Ph3NSO and acetone by centrifugation, washing with pure water, and centrifugation, long-afterglow PS (Polystyrene) nanospheres with TPP+Ph3NSO were obtained.

[0164] The tests in Example 1 and Comparative Example 1 were based on molecular-state spectroscopy and other tests. To enable application in aqueous solutions, PS microspheres were used for coating. Monomolecular TPP-Ph3NSO was coated into PS nanospheres. Here, a swelling method was used to place the TPP-Ph3NSO molecules into the polystyrene microspheres, and the tests were conducted in an aqueous solution, specifically testing the nanospheres from Example 6. The results are as follows. Figure 11 As shown in the scanning electron microscope image, the PS spheres still maintain a good morphology after encapsulating the TPP-Ph3NSO molecule. Figure 12 Dynamic light scattering revealed that the size distribution of the single-molecule TPP-Ph3NSO polystyrene microspheres after the reaction was relatively uniform. The preparation of long-afterglow nanoparticles with uniform size and morphology is of great significance for their development in the biomedical field. First, it facilitates the surface functionalization of long-afterglow nanoparticles; second, the uniform size and morphology of long-afterglow nanoparticles improves the reproducibility of biomedical experiments; finally, controllable material preparation is crucial for their future clinical translation.

[0165] Fluorescence spectroscopy was performed on the coated PS microspheres in Example 6 and Comparative Example 2. The results are shown in [reference needed]. Figure 13 and Figure 14 The fluorescence spectra of the coated nanospheres in Example 6 and Comparative Example 2 are basically the same.

[0166] In addition, afterglow spectroscopy tests were performed on the coated PS microspheres in Example 6 and Comparative Example 2, and the results are shown in [reference needed]. Figure 15 and Figure 16 When the two components are mixed, the emitted light still contains triphenylamine emission, resulting in lower energy transfer efficiency. When designed as a single molecule, the emission is porphyrin near-infrared emission, thus exhibiting higher energy transfer efficiency and better near-infrared penetration. The luminescence lifetimes of the coated PS microspheres in Example 6 and Comparative Example 2 are shown in [reference needed]. Figure 17 and Figure 18 The luminescence quantum efficiency (QQE) of TPP+Ph3NSO molecules coated with nanospheres is 4.62 seconds, and the light intensity decay of the multi-component group follows a single exponential decay pattern. The QQE of TPP-Ph3NSO molecules coated with nanospheres is 5.03 seconds, and the light intensity decay of the single-component group also follows a single exponential decay pattern. However, the single-component group has a longer luminescence lifetime than the two-component group, thus better meeting the quantitative needs in vivo. Calculations show that the luminescence quantum efficiency of TPP+Ph3NSO molecules is 3.1%, while that of TPP-Ph3NSO molecules is 5.2%, which is equivalent to a 40% increase in luminescence quantum efficiency after covalent coupling compared to the physical mixing of the two components.

[0167] Because single-molecule long afterglow enables efficient intramolecular energy transfer and exhibits single-exponential luminescence decay in both organic solvents and water, its luminescence is less affected by external conditions, allowing for stable acquisition of experimental data. Therefore, it has excellent applications in diagnostics, imaging, and information encryption. The following application examples illustrate this.

[0168] Application Example 1

[0169] This application example demonstrates the application of the aforementioned long-persistence compounds and systems in the field of bioimaging.

[0170] Because TPP-Ph3NSO has high near-infrared emission, it has significant advantages in biological imaging such as cell imaging, small animal imaging, and CT imaging. In terms of tissue penetration, near-infrared light has a deeper penetration depth and higher resolution than ultraviolet and visible light, which means clearer imaging results.

[0171] The single-component long-afterglow molecule TPP-Ph3NSO synthesized in Example 1 and TPP+Ph3NSO from Comparative Example 1 were injected subcutaneously into different mice, respectively, using a power density of 70 mW / cm². 2 After irradiating with a 680nm laser for 5 seconds, the laser was turned off, and the afterglow signal was collected. The intensity of the afterglow signal of TPP-Ph3NSO in vivo was higher than that of BPEA NPs, and the imaging signal-to-noise ratio could reach up to 105.

[0172] Application Example 2

[0173] This application example demonstrates the application of the aforementioned long-afterglow compounds and systems in the field of photodynamic therapy.

[0174] Photodynamic therapy (PDT) is a highly selective and non-invasive treatment suitable for various cancerous and non-cancerous lesions. Generally, PDT uses an external light source to activate a photosensitizer, generating reactive oxygen species (ROS) such as singlet oxygen, which can kill cancer cells. 1 While photosensitizers can be activated in the visible to near-infrared range, this wavelength range is limited by tissue penetration depth and scattering issues, preventing traditional photodynamic therapy (PDT) from treating deep tumors. Nanomaterials with long afterglow (TPP-Ph3NSO) can continuously emit light after the excitation source is removed, exhibiting regular morphology and uniform size. Using TPP-Ph3NSO for photodynamic therapy can overcome the limitations of tumor depth and provide continuous emission. 1 O2 reduces the number and duration of X-ray irradiation, thus minimizing radiation damage to normal tissues. Furthermore, nanoparticles in the 20–200 nm size range exhibit high penetration and long retention at tumor sites, and when combined with appropriate TPP-Ph3NSO molecules in X-PDT, this will broaden the application of photodynamic therapy in clinical cancer treatment.

[0175] Furthermore, the long-afterglow luminescent nanomaterial TPP-Ph3NSO has a long luminescence lifetime. Due to its persistent luminescence, it can be used to determine the precise location and time required for treatment. At the same time, the long afterglow has significant penetration depth and biocompatibility, and can be integrated to provide a variety of afterglow imaging-guided therapies.

[0176] Application Example 3

[0177] This application example demonstrates the application of the aforementioned long-afterglow compounds and systems in the field of immunoassay.

[0178] Immunoassay primarily utilizes the specific reaction between antigens and antibodies for detection. Isotopes, enzymes, and chemiluminescent substances are used to amplify and display the detection signal. It is commonly used to detect trace substances such as proteins and hormones, playing a crucial role in clinical diagnosis. One important type of common immunoassay technique is chemiluminescence. Because TPP-Ph3NSO combines three components into a single molecule, changes in the surrounding environment have minimal impact on its luminescence, allowing it to be used in various environments. When TPP-Ph3NSO is adsorbed onto nanospheres, these nanospheres exhibit excellent dispersibility in water.

[0179] Application Example 4

[0180] This application example demonstrates the application of the aforementioned long-afterglow compounds and systems in the field of chemical / biological sensing.

[0181] Highly target-selective and sensitive probes for chemi / biosensing play a crucial role in chemical / biomedical detection. For example, the detection of tumor biomarkers, metabolites, biomolecules, and other essential signals in living cells is vital for disease treatment diagnosis and systematic studies of cell viability. TPP-Ph3NSO exhibits persistent afterglow luminescence, allowing for chemi / biosensing without background noise interference. In particular, TPP-Ph3NSO's near-infrared emission demonstrates high penetration depth in biological tissues, good photostability and chemical stability, and low toxicity, making it widely applicable in chemi / biosensing processes.

[0182] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. A long afterglow compound based on covalent coupling, characterized in that, The long afterglow compound absorbs photons and transfers the absorbed photon energy within the molecule, where a photochemical reaction occurs and the photochemical energy is released in the form of light energy, thus achieving afterglow luminescence. The structure of the long afterglow compound is as follows:

2. A long-persistence system based on covalent bond coupling, characterized in that, The invention includes a support medium and the long afterglow compound based on covalent coupling as described in claim 1, wherein the support medium is used to dissolve, disperse, or adsorb the long afterglow compound.

3. The long-persistence system based on covalent bond coupling according to claim 2, characterized in that, The carrier medium is an organic solution or an aqueous medium.

4. The long-persistence system based on covalent bond coupling according to claim 3, characterized in that, The organic solution is any one of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, halogenated hydrocarbons, alcohols, esters, and ketones.

5. The long afterglow system based on covalent bond coupling according to claim 3, characterized in that, The aqueous medium is any one of nano-dispersion, microsphere dispersion, and nanomicelle dispersion.

6. The long-persistence system based on covalent bond coupling according to claim 2, characterized in that, The long afterglow system can exist in any of the following forms: nanomaterials, thin films, gels, and biological media.

7. A method for preparing a long afterglow system based on covalent coupling as described in any one of claims 2-6, characterized in that, include: The following reaction yields long-afterglow compounds based on covalent coupling: The long-afterglow compound was dissolved in a support medium and purified by stirring to obtain a long-afterglow system based on covalent coupling.

8. The application of a long-persistent compound based on covalent coupling as described in claim 1 or a long-persistent system based on covalent coupling as described in any one of claims 2-6, wherein the application is in the preparation of bioimaging reagents, photodynamic therapy reagents, immunoassay reagents, or chemical / biological sensing reagents.

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