A small-size porphyrin-based aie conjugated oligomer nanomaterial and a preparation method thereof

Abstract

A small-size porphyrin-based AIE conjugated oligomer nanomaterial and a preparation method thereof, the small-size porphyrin-based AIE nanomaterial containing a tetraphenylporphyrin-tetraphenylstyrene-quaternary ammonium group. The application also includes a preparation method of the small-size conjugated oligomer nanomaterial. The small-size conjugated oligomer nanoparticle has a water-soluble positively charged quaternary ammonium group, a near-infrared characteristic tetraphenylporphyrin group and a tetraphenylstyrene group with AIE effect. The porphyrin group has strong rigidity and hydrophobicity, and the characteristic quaternary ammonium group is introduced into the conjugated main chain to improve the hydrophilicity of the conjugated main chain and form a small-size nanoparticle; the introduction of the tetraphenylstyrene group with AIE effect can realize the AIE effect of the novel conjugated oligomer and the modulation of the small-size nanoparticle probe luminescence performance. The average particle size of the small-size porphyrin-based AIE conjugated oligomer nanomaterial is about 4.64 nm, which helps to improve the sensitivity and specificity of the conjugated oligomer nanomaterial fluorescence analysis.

Description

TECHNICAL FIELD

[0001] The present application relates to a conjugated oligomer nanomaterial and a synthesis method thereof, in particular to a small-size conjugated oligomer nanomaterial and a synthesis method thereof. BACKGROUND

[0002] Conjugated polymers (CPs) are a kind of organic macromolecules, whose delocalized pi-electron system can absorb light energy and convert into fluorescence, thermal energy and other energy. However, due to the hydrophobicity of its organic structure, there are limitations in biological applications, so it is necessary to prepare water-soluble conjugated polymer nanoparticles (Nanomaterials 2023, 13, 1543). Conjugated polymer nanoparticles are widely used in biological sensing, cell imaging, optical therapy and drug delivery (Bioorganic Chemistry 145 (2024) 107188, Biomacromolecules 2023, 24, 1943-1979) due to their good light stability, high molar absorption coefficient and good biocompatibility. As analogues of conjugated polymer nanoparticles, conjugated oligomer nanoparticles (CONs) have high fluorescence quantum yield and stability. They are usually prepared from smaller molecular size and precise structure oligomers. Compared with conjugated polymers, conjugated oligomers are easier to control and purify. Due to their excellent properties, they are widely used in fluorescence detection and imaging, cancer cell target recognition, photodynamic therapy (PDT) and chemotherapy (ACS Appl. Bio Mater. 2019, 2, 1340-1347, CN113069557B, CN117986275A).

[0003] The AIE (aggregation-induced emission) phenomenon overcomes the deficiency that the fluorescence group is easily quenched when it aggregates (Chem. Commun., 2001, 1740-1741). AIE polymers have the advantages of high emission efficiency of aggregates and solid state, good multifunctionalization and good signal amplification effect, and have been widely used in the fields of optoelectronic devices, chemical / biological sensing and biomedical science (Progress in Polymer Science 100 (2020) 101176).

[0004] Porphyrin and its derivatives are known as life pigments, which have excellent light trapping ability and near-infrared emission characteristics, and are widely used in photovoltaics, biomedicine, biological / chemical sensing, photocatalytic hydrogen evolution and carbon dioxide reduction (Aggregate 2023, e330). Porphyrin is a kind of heterocyclic aromatic organic compound. Due to its strong pi-pi stacking, porphyrin has a significant ACQ (aggregation-induced quenching) effect (Anal. Chem. 2022, 94, 17709-17715).

[0005] Conjugated oligomers containing quaternary ammonium groups can aggregate with negatively charged bioactive molecules, and the quaternary ammonium groups are water-soluble, forming water-soluble sensing materials. This facilitates the construction of novel "amphiphilic" oligomers, leading to the formation of specific, highly sensitive novel small-sized (~1-9 nm) conjugated oligomer nanoprobes (Chem. Soc. Rev., 2022, 51, 9917–

[0006] 9932).

[0007] Existing conjugated polymer nanomaterials often exhibit aggregation-induced quenching in water due to their large conjugated structure, thus reducing fluorescence quantum yield. At the same time, because conjugated polymers have large molecular weights, they tend to form large nanospheres during nanoparticle preparation, which reduces the sensitivity of nanoprobes. In addition, most existing nanomaterials emit light in the ultraviolet-visible region, which introduces a lot of background interference when applied to bioimaging, thus limiting their application range. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a small-sized porphyrin-based AIE conjugated oligomer nanomaterial. The small-sized porphyrin-based AIE conjugated oligomer has a low degree of polymerization, is hydrophilic, and has the AIE effect. The small-particle nanoparticle material made from it has a particle size of only 1-9 nm. The conjugated oligomer has a strong fluorescence emission phenomenon in the near-infrared range (660 nm to 700 nm).

[0009] A further technical problem to be solved by the present invention is to provide a method for preparing the small-sized porphyrin-based AIE conjugated oligomer nanomaterials.

[0010] The technical solution adopted by the present invention to solve its technical problem is: a small-sized conjugated oligomer nanomaterial, which is a conjugated oligomer containing tetraphenylporphyrin-tetraphenylene-quaternary ammonium fluorene groups, and the chemical structural formula of the conjugated oligomer is shown in Formulas I to IV, wherein, in Formulas I and III, 2x+y=1; in Formulas II and IV, x+y=1;

[0011]

[0012]

[0013] Furthermore, the metal M in the center of the tetraphenylporphyrin includes various metals that can enter the central position of the porphyrin.

[0014] such as Zn 2+ Eu 2+ wait.

[0015] The technical solution adopted by this invention to further solve its technical problem is a method for preparing the small-sized porphyrin-AIE conjugated oligomer nanomaterial, comprising the following steps: using halobromoalkylfluorene, halotetraphenylporphyrin, and tetraphenyl boronic acid ester as raw material monomers, in the presence of a catalyst and a basic salt, in a solvent, a conjugated oligomer of tetraphenylporphyrin-tetraphenyl-bromoalkylfluorene is synthesized by a Suzuki coupling polycondensation reaction, wherein the chain length of the alkane on the raw material halobromoalkylfluorene is changed to modify its structure, and then a quaternization reaction is carried out with trimethylamine to obtain a conjugated oligomer containing tetraphenylporphyrin-tetraphenyl-quaternary ammonium fluorene; then, a trace amount of N,N-dimethylformamide is used to dissolve it, and methanol is added; a surfactant is dissolved in methanol, and the above two solutions are mixed to obtain a mixed conjugated oligomer solution with a concentration of 100-200 ppm; the obtained mixed conjugated oligomer solution is injected into water, sonicated, and then rotary evaporated to remove the solvent, thereby obtaining the target product.

[0016] Furthermore, the catalyst used in the suzuki coupling polycondensation reaction is Pd(PPh3)4, and the basic salt is anhydrous potassium carbonate.

[0017] Furthermore, the temperature of the polycondensation reaction is 70–90°C, preferably 75–85°C, and more preferably 80°C.

[0018] Furthermore, the polycondensation reaction takes 36-55 hours, preferably 40-50 hours, and more preferably 48 hours.

[0019] Furthermore, the amount of the catalyst Pd(PPh3)4 is 5% to 10% of the amount of tetraphenylethylene borate ester.

[0020] Furthermore, the molar ratio of the raw material monomer tetrastyrene borate ester (n) to halotetraphenylporphyrin (x) and bromoalkylfluorene (y) is n:(x+y) or n:(2x+y) 1.0:1.0~1.2.

[0021] Furthermore, the ratio of the raw material monomers halotetraphenylporphyrin (x) and halobromoalkylfluorene (y) is controlled according to the ratio of functional groups, which is x+y=1 or 2x+y=1.

[0022] Furthermore, the alkanes with different chain lengths on the halobromoalkylfluorene monomers are 1,6-dibromopropane, 1,6-dibromobutane, 1,6-dibromopentane, and 1,6-dibromohexane.

[0023] Furthermore, the amine used in the quaternization reaction is trimethylamine; the solvent is tetrahydrofuran and methanol; the amount of trimethylamine is 20 to 100 times the amount of the tetraphenylporphyrin-tetraphenylene-bromoalkylfluorene conjugated oligomer; and the volume ratio of tetrahydrofuran to methanol is 1:0.25 to 1.

[0024] This invention discloses a method for preparing small-sized porphyrin-based AIE conjugated oligomer nanomaterials, the specific steps of which are as follows:

[0025] S1. Preparation of tetraphenylporphyrin-tetraphenylphenyl-bromoalkylfluorene conjugated oligomer: Tetraphenylphenyl boronic acid ester, halotetraphenylporphyrin, halobromoalkylfluorene, anhydrous potassium carbonate and catalyst Pd(PPh3)4 are weighed according to the molar ratio. The air is replaced with an inert gas, and then a mixed solution of toluene and water (pre-deoxygenated) is added under an inert gas atmosphere to form a reaction solution. The reaction solution is heated to 70-90℃ (preferably 75-85℃, more preferably 80℃) and reacted for 36-55h (preferably 40-50h, more preferably 48h). After cooling to room temperature, dilution with dichloromethane is added, and the product is washed with deionized water. After extraction and separation, the product is dried with anhydrous sodium sulfate, filtered, and the solvent is removed by rotary evaporation. The crude product is dissolved in dichloromethane, and then methanol is added dropwise. After centrifugation, the precipitate is washed with methanol and dried under vacuum to obtain the tetraphenylporphyrin-tetraphenylphenyl-bromoalkylfluorene conjugated oligomer.

[0026] S2. Preparation of tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene conjugated oligomer: Weigh the tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer obtained in step S1, dissolve it in tetrahydrofuran, add 50% trimethylamine, react at room temperature for 6-18 h (preferably 10-15 h, more preferably 12 h), add MeOH, dissolve, then add the remaining 50% trimethylamine, react for 12-48 h (preferably 18-40 h, more preferably 22-30 h, even more preferably 24 h), remove the solvent by rotary evaporation, dissolve in tetrahydrofuran, add acetone, centrifuge, and obtain the tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene conjugated oligomer;

[0027] S3. Preparation of mixed conjugated oligomer solution: The tetraphenylporphyrin-tetraphenylene-quaternary ammonium fluorene conjugated oligomer obtained in step S2 is dissolved in N,N-dimethylformamide, and then methanol is added; the surfactant is dissolved in methanol, and the two solutions are mixed to obtain a mixed conjugated oligomer solution with a concentration of 100-200 ppm.

[0028] S4. Preparation of nanoparticle materials: The mixed conjugated oligomer solution obtained in step S3 is rapidly injected into deionized water under ultrasonic conditions, followed by ultrasonication and then rotary evaporation to remove the solvent, thereby obtaining small-sized porphyrin-based AIE conjugated oligomer nanomaterials.

[0029] The small-sized porphyrin-based AIE conjugated oligomer nanomaterials prepared by this invention have a particle size <9 nm and relatively uniform particle size. This is a novel type of AIE nanoparticle material. It exhibits excellent water dispersibility and is readily soluble in organic solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and methanol, making it suitable for a wide range of applications and various detection systems.

[0030] Furthermore, in step S1, the volume ratio of toluene to deionized water in the mixed solution of toluene and water is 1:0.2 to 0.8, preferably 1:0.6.

[0031] Furthermore, in step S1, the concentration of tetraphenyl boronic acid ester in the reaction solution is 4.0–20.0 mmol / L, preferably 8.0 mmol / L.

[0032] Furthermore, in step S2, the amount of trimethylamine is 20 to 100 times the amount of tetraphenylporphyrin-tetraphenylene-bromoalkylfluorene obtained in step S1.

[0033] Furthermore, in step S2, the concentration of the tetraphenylporphyrin-tetraphenylene-bromoalkylfluorene conjugated oligomer in tetrahydrofuran is 10–40 mg / mL.

[0034] In step S3, if the concentration of the mixed conjugated oligomer solution is too low, the conjugated oligomers will have difficulty agglomerating to form nanoparticles, resulting in a low product yield; if the concentration is too high, the conjugated oligomers will be more likely to agglomerate, resulting in larger nanoparticle sizes.

[0035] Further, in step S3, the surfactant is selected from one of mPEG-COOH-350, DSPE-PEG-2000, HOOC-PEG-COOH and F127; wherein, the structural formula of mPEG-COOH-350 is shown in Formula V, the structural formula of DSPE-PEG-2000 is shown in Formula VI, the structural formula of HOOC-PEG-COOH is shown in Formula VII, and the structural formula of F127 is shown in Formula VIII.

[0036]

[0037] Furthermore, in step S3, the mass ratio of the surfactant to the conjugated polymer is 10 to 25:1.

[0038] Furthermore, in step S3, the concentration of the surfactant solution is 0.001 g / mL to 0.00125 g / mL.

[0039] The methanol is a volatile solvent; the addition of N,N-dimethylformamide is to aid in the dissolution of the conjugated oligomers, which can be removed by azeotropic reaction with water during rotary evaporation.

[0040] Furthermore, in step S4, the ultrasound duration is 2 to 12 hours.

[0041] In steps S1 and S2, the reaction temperature, time, and other conditions will affect the degree of polymerization of the conjugated oligomers. Therefore, they should be appropriately controlled.

[0042] The catalyst Pd(PPh3)4 can be synthesized by the following method: PdCl2, triphenylphosphine, and DMSO are mixed in a mass ratio of 1:5 to 10:50 to 150. The air is replaced three times with an inert gas, and the temperature is raised to 140 to 150°C. After reacting under these conditions for 15 to 20 minutes, a bright yellow liquid is obtained. Then, hydrazine hydrate is slowly added dropwise at a rate of 0.5 to 1.5 mL / min with a mass ratio of hydrazine hydrate to DMSO of 1:60 to 100 under low-speed stirring. The reaction solution turns wine red. After the addition is complete, stirring is stopped, the mixture is cooled, filtered, and the crude product is washed 5 times with anhydrous ethanol and 3 times with diethyl ether to obtain the golden yellow solid catalyst Pd(PPh3)4. The catalyst is stored under vacuum at -5°C.

[0043] Furthermore, in step S2, the halobromoalkylfluorene is 2,7-diiodo-9,9-bis(6'-bromohexyl)fluorene.

[0044] The 2,7-diiodo-9,9-bis(6'-bromohexyl)fluorene can be synthesized by the following method:

[0045] (a) A mixed solution of CH3COOH, H2O and H2SO4 was measured in a volume ratio of 50:4:1 and added to a 250 mL three-necked flask. The mixture was stirred and heated to 80 °C. Then, fluorene, potassium iodate and iodine were added in a molar ratio of 15:6:16. The mixture was reacted for 10 h. The mixed solution turned purple and formed a precipitate. The solution was cooled, filtered, and the precipitate was collected. The precipitate was washed with 50 mL of water and 50 mL of 2 mol / L Na2CO3 solution. The crude product was recrystallized from CH2Cl2 to give a pale yellow solid 2,7-diiodofluorene.

[0046] (b) Measure 30 mL of 50% KOH aqueous solution into a 250 mL three-necked flask, stir and heat to 75 °C, then add the intermediate 2,7-diiodofluorene, tetrabutylammonium bromide and 1,6-dibromohexane described in step (a) in a molar ratio of 1.2:0.26:12. After reacting for 15 min, the reaction solution is rapidly cooled to room temperature and extracted three times with CH2Cl2. The organic layer is washed with 1 mol / L HCl, deionized water and brine respectively, dried with anhydrous Na2SO4, filtered, the solvent is removed by vacuum distillation, and separated by column chromatography to obtain 2,7-diiodo-9,9-di(6'-bromohexyl)fluorene.

[0047] The beneficial effects of this invention are as follows:

[0048] (1) The conjugated oligomers obtained in this invention have a low degree of polymerization and a small molecular weight, which makes it easy to form novel nanoparticles with small particle size and superior performance. In addition, they contain quaternary ammonium fluorene groups and tetraphenylethylene groups. The tetraphenylethylene groups have the AIE effect, and the quaternary ammonium groups are water-soluble, which is conducive to the formation of water-soluble AIE nanoparticles. At the same time, the tetraphenylethylene groups and quaternary ammonium fluorene groups of the conjugated oligomers have strong fluorescence emission. Because the quaternary ammonium groups are positively charged, they are easy to aggregate with negatively charged groups through electrostatic interaction, which is beneficial to the sensitive detection and imaging of substances in aqueous solutions and cellular environments.

[0049] (2) This invention successfully synthesized conjugated oligomers with low degree of polymerization via Suzuki coupling condensation reaction. By controlling the molar ratio of tetraphenyl boronic acid ester, halotetraphenyl porphyrin, and haloquaternary ammonium fluorene, novel conjugated oligomers with different proportions were synthesized. At the same time, by changing the chain length of the alkane on the quaternary ammonium fluorene, similar different conjugated oligomers can also be synthesized. The reaction temperature, time and other conditions also affect the degree of polymerization of the conjugated oligomers, and this invention has also made appropriate controls.

[0050] (3) By controlling the concentration of the conjugated oligomer solution and selecting the surfactant, the present invention successfully prepared novel AIE nanoparticles with good dispersibility and small particle size (<9nm) using a modified nanoprecipitation method. These nanoparticles can be applied to cell imaging and detection of bioactive molecules, which helps to significantly reduce the detection limit and improve the sensitivity of the detection method.

[0051] (4) The nanoparticles prepared by the method of the present invention have excellent water dispersibility, relatively uniform particle size, and are easily soluble in organic solvents such as N,N-dimethylformamide, dimethyl sulfoxide and methanol. They have a wide range of applications and are suitable for different detection systems. At the same time, the method is simple and easy to implement and has low investment cost. Attached Figure Description

[0052] Figure 1 This is the 1H NMR spectrum of the conjugated oligomer synthesized in Example 1 of the present invention;

[0053] Figure 2 This is a TEM image of nanoparticles prepared using the conjugated oligomer synthesized in Example 1 in Example 2;

[0054] Figure 3 This is a size distribution diagram of nanoparticles prepared using the conjugated oligomer synthesized in Example 1 in Example 2;

[0055] Figure 4 These are the UV absorption and fluorescence spectra of the conjugated oligomers synthesized in Example 1;

[0056] Figure 5The fluorescence spectra of the conjugated oligomers synthesized in Example 1 and the fluorescence spectra of the nanoparticles prepared using the conjugated oligomers synthesized in Example 2 are shown below.

[0057] Figure 6 These are the fluorescence spectra of the conjugated oligomers synthesized in Example 1 at different H2O / DMF volume ratios and the fluorescence intensity variation at 505 nm.

[0058] Figure 7 This is a schematic diagram of the process for preparing small-sized porphyrin-based AIE conjugated oligomer nanomaterials according to Example 2 of the present invention. Detailed Implementation

[0059] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0060] The nitrogen gas used in the embodiments of the present invention is high-purity nitrogen gas with a purity ≥ 99.999%; the argon gas is high-purity argon gas with a purity ≥ 99.999%. Unless otherwise specified, the chemical reagents used in the embodiments of the present invention are obtained through conventional commercial channels.

[0061] Reference Example 1: Synthesis of tetra(triphenylphosphine)palladium catalyst used in the method of the present invention

[0062] PdCl2, triphenylphosphine, and dimethyl sulfoxide are mixed in a mass ratio of 1:5–10:50–150 (more preferably 1:6–8:80–120). Under nitrogen protection, the mixture is stirred and heated to 140–160°C. After reacting at this temperature for 12–18 min, the solution color changes from yellow to red. Then, hydrazine hydrate is added dropwise at a rate of 0.5–1.5 mL / min at a mass ratio of hydrazine hydrate to dimethyl sulfoxide of 1:60–100 (more preferably 1:70–90). The reaction is stopped, the mixture is allowed to stand, cooled, and filtered. The filter residue is washed with ethanol ≥4 times and with diethyl ether ≥2 times to obtain the final product.

[0063] Reference Example 2: Synthesis of 2,7-diiodo-9,9-di(6'-bromohexyl)fluorene, one of the raw materials used in the method of the present invention.

[0064] 165 mL of a mixed solution (CH3COOH:H2O:H2SO4, V / V, 50:4:1) was added to a 250 mL three-necked flask. The solution was heated to 80 °C, and then fluorene (2.54 g, 15 mmol), KIO3 (1.28 g, 6 mmol), and I2 (4.1 g, 16.2 mmol) were added. The mixture was refluxed for 10 h. The solution was cooled to room temperature, filtered, and the precipitate was washed with 100 mL of deionized water and 200 mL of 2 M Na2CO3 solution. The crude product was recrystallized from dichloromethane and dried to give a white solid, 2,7-diiodofluorene.

[0065] In a 100 mL three-necked flask, 30 mL of 50% KOH solution was added, followed by 2,7-diiodofluorene (0.5 g, 1.2 mmol), tetrabutylammonium bromide (0.085 g, 0.26 mmol), and 1,6-dibromohexane (3.0 g, 12 mmol). The mixture was reacted at 75 °C for 15 min, and then rapidly cooled to room temperature. The solution was extracted with 50 mL of dichloromethane, and the organic layer was washed with 50 mL of 1 mol / L HCl solution, 50 mL of deionized water, and 50 mL of NaCl solution, respectively. The solution was then dried over anhydrous sodium sulfate, filtered, and the organic solvent was removed by vacuum distillation. The solution was then separated by column chromatography (petroleum ether:dichloromethane, V / V, 35:1) to give a white solid, 2,7-diiodo-9,9-bis(6'-bromohexyl)fluorene.

[0066] Example 1: Synthesis of the intermediate product conjugated oligomer of the present invention

[0067] The synthesis reaction formula is as follows:

[0068]

[0069] Synthetic reaction formula IX illustrates the synthesis steps of the conjugated oligomer in this embodiment. The specific operation method includes the following steps:

[0070] (1) Add 1,2-diphenyl-1,2-bis(4-pinacolyl ester phenyl)ethylene (0.2 mmol, 120.5 mg), 2,7-diiodo-9,9-bis(6'-bromohexyl)fluorene (0.18 mmol, 133.9 mg), 5,10,15,20-tetratetra(4-bromophenyl)porphyrin (0.01 mmol, 9.8 mg), and Pd(PPh3)4 (0.02 mmol, 23.1 mg) to a 50 mL round-bottom flask. The reaction mixture was prepared by adding 9 mL of water and 14 mL of toluene to tetrabutylammonium bromide (0.02 mmol, 6.6 mg) and anhydrous potassium carbonate (24.8 mmol, 3.43 g), and reacting at 80 °C under an Ar atmosphere for 48 h. After the reaction was stopped, the reaction mixture was cooled to room temperature, diluted with DCM (50 mL), washed with deionized water (50 mL × 3), extracted and separated, dried with anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation. The crude product was dissolved in 1 mL of DCM, and 50 mL of methanol was slowly added dropwise. After centrifugation, a light brown solid was obtained.

[0071] (2) Weigh 50 mg (0.03 mmol) of the light brown solid obtained in step (1) into a 50 mL round bottom flask, add 5 mL THF and 0.5 mL trimethylamine, react at 25 °C for 12 h, add 2 mL methanol, sonicate to dissolve the black precipitate on the flask wall, add 0.5 mL trimethylamine, and then reflux at 25 °C for 24 h. After the reaction is completed, remove the solvent and excess trimethylamine by rotary evaporation, add 1 mL THF and 50 mL acetone for recrystallization, centrifuge to obtain the dark brown target product conjugated oligomer solid (FNTT).

[0072] NMR characterization: Refer to Figure 1 , Figure 2 A certain amount of the conjugated oligomer (FNTT) was weighed and dissolved in 600 μL of deuterated dimethyl sulfoxide reagent. The dissolution was performed with ultrasonic assistance. The resulting solution was then transferred to an NMR tube for NMR characterization. The proton NMR spectrum is shown below. Figure 1 and Figure 2 As shown, the specific data is as follows: 1 H NMR (500MHz, DMSO-d6): δ8.01 (s, 0.12h), δ7.68-7.61 (m, 6H), 7.26-7.05 (m, 18H),2.95(m,22H),2.10(br,4H),1.44(br,4H),1.02(br,8H),0.54(br,4H). The very weak 0.12 proton hydrogens at 8.01 ppm are proton hydrogens on the benzene ring in tetraphenylporphyrin; the 6 proton hydrogens at 7.68 ppm-7.61 ppm are 6 proton hydrogens on the benzene ring in fluorene; the 18 proton hydrogens at 7.26 ppm-7.05 ppm are proton hydrogens on the benzene ring in tetraphenylphenyl; the 2.95 ppm proton hydrogens are 18 proton hydrogens of the quaternary ammonium salt and the proton hydrogens of the two methylene groups attached to the quaternary ammonium group; and the 20 proton hydrogens at 2.10 ppm, 2.10 ppm, 1.44 ppm, and 1.02 ppm are proton hydrogens of the alkyl chain attached to fluorene.

[0073] Example 2: Preparation method of small-sized porphyrin-based AIE conjugated oligomer nanomaterials of the present invention

[0074] (1) Weigh 1.0 mg of the conjugated oligomer obtained in Example 1 and dissolve it in 20 μL of DMF, then add 5 mL of MeOH solution to prepare a 200 ppm solution;

[0075] (2) Weigh 0.020g mPEG-COOH-350 and dissolve it in 5mL MeOH to prepare a surfactant solution of 4000ppm;

[0076] (3) Mix the solutions prepared in steps (1) and (2) evenly to form a 100 ppm mixed solution. Under ultrasonic conditions, rapidly inject the mixed solution into 20 mL of deionized water, sonicate for 12 h, and remove the solvent by rotary evaporation (assuming that the energy of the water is not lost) to obtain small nanoparticle materials with a size of about 4.64 nm.

[0077] TEM images of the small-sized porphyrin-based AIE conjugated oligomer nanomaterials prepared in this embodiment are shown below. Figure 2 As shown; its particle size distribution is relatively uniform, consisting of small nanoparticles with a particle size of approximately 1–9 nm; it exhibits excellent water dispersibility in aqueous solutions; such as Figure 3 As shown, the average diameter of the nanoparticles is approximately 4.64 nm.

[0078] Figure 4 These are the UV absorption and fluorescence spectra of the conjugated oligomers synthesized in Example 1. In the UV absorption spectrum, 361 nm is the peak of quaternary ammonium fluorene, and 415 nm is the S-band of porphyrin. Due to the small proportion of porphyrin, the Q-band is not obvious. In the fluorescence spectrum, 505 nm is the characteristic peak of quaternary ammonium fluorene, and 660 nm is the near-infrared characteristic peak of porphyrin.

[0079] 1 mL of the nanoparticle solution was transferred to a fluorescent cuvette, and its fluorescence spectrum was measured. The spectrum is shown below. Figure 5 As shown, the polymer nanoparticle solution has a maximum emission peak at 505 nm.

[0080] Figure 6 The graph shows the fluorescence spectra of the conjugated oligomer synthesized in Example 1 at different volume ratios of H2O / DMF and the fluorescence intensity change at 505 nm. As can be seen from the graph, the fluorescence at 505 nm gradually increases with the increase of water volume, which proves that the synthesized conjugated oligomer has the AIE effect.

[0081] Figure 7 This is a schematic diagram illustrating the mechanism of the small-sized porphyrin-based AIE conjugated oligomer nanomaterials prepared in Example 2. The conjugated oligomer FNTT, encapsulated by the surfactant mPEG-COOH-350, was dissolved in methanol, then injected into deionized water under ultrasonic conditions and sonicated for 2–12 hours. After removing the volatile organic solvent methanol, small-sized conjugated oligomer nanoparticles (FNTTNPs, ~4.64 nm) were formed. Furthermore, at an excitation wavelength of 427 nm, the FNTT nanoparticles emitted peaks at 505 nm and 660 nm.

Claims

1. A small size porphyrin-based AIE conjugated oligomer nanomaterial, characterized in that, The chemical structure of the conjugated oligomer is shown in the following formula I~IV: ； ； ； ； In formula I and formula III, 2x + y = 1; in formula II and formula IV, x + y = 1; The small-size porphyrin-based AIE conjugated oligomer nanomaterial is synthesized by using halogenated bromoalkylfluorene and halogenated tetraphenylporphyrin and tetraphenylstyrene borate as raw material monomers; the particle size is 1-9 nm. The metal M in the middle of the tetraphenylporphyrin is Zn 2+ or Eu 2+ .

2. The preparation method of the small-size porphyrin-based AIE conjugated oligomer nanomaterial according to claim 1, characterized in that, The method comprises the following steps: The conjugated oligomer of tetraphenylporphyrin-tetraphenylstyrene-bromoalkylfluorene is synthesized by using halogenated bromoalkylfluorene and halogenated tetraphenylporphyrin and tetraphenylstyrene borate as raw material monomers, under the action of a catalyst and an alkaline salt, in a solvent, through a suzuki coupling polycondensation reaction, wherein the structure is adjusted by changing the chain length of the alkane on the halogenated bromoalkylfluorene raw material, and then a quaternary ammonium group is obtained through a quaternary ammonium reaction with trimethylamine, to obtain the conjugated oligomer containing tetraphenylporphyrin-tetraphenylstyrene-quaternary ammonium group fluorene; then the conjugated oligomer containing tetraphenylporphyrin-tetraphenylstyrene-quaternary ammonium group fluorene is dissolved in N,N-dimethylformamide, and methanol is added; the surfactant is dissolved in methanol, the above two solutions are mixed to obtain a mixed conjugated oligomer solution with a concentration of 100-200 ppm, the obtained mixed conjugated oligomer solution is injected into water, ultrasonic treatment is performed, and then rotary evaporation is performed to remove the solvent, to obtain the target product.

3. The preparation method according to claim 2, characterized in that, The catalyst used in the suzuki coupling polycondensation reaction is Pd(PPh3)4; the alkaline salt used is anhydrous potassium carbonate; the temperature of the coupling polycondensation reaction is 70-90℃, the reaction time is 36-60 h; the amount of substance of the Pd(PPh3)4 is 5%-10% of the amount of substance of the tetraphenylstyrene borate; the amount of substance of the anhydrous potassium carbonate is 10%-13% of the amount of substance of the tetraphenylstyrene borate; the amount of substance ratio of the tetraphenylstyrene borate n to the halogenated tetraphenylporphyrin x and the halogenated bromoalkylfluorene y is n:x+y or n:2x+y, and the ratio of the halogenated tetraphenylporphyrin to the halogenated bromoalkylfluorene is adjusted according to different amounts of substance; the halogenated alkane with different chain lengths in the quaternary ammonium group fluorene group is 1,6-dibromopropane, 1,6-dibromobutane, 1,6-dibromopentane or 1,6-dibromohexane.

4. The preparation method according to claim 3, characterized in that, The solvent is tetrahydrofuran and methanol; the amount of substance of the trimethylamine is 20-100 times the amount of substance of the tetraphenylporphyrin-tetraphenylstyrene-bromoalkylfluorene conjugated oligomer; the ratio of the tetrahydrofuran to the methanol is 1:0.25-1.

5. The preparation method according to claim 4, characterized in that, The temperature of the quaternary ammonium reaction is 0℃-30℃.

6. The preparation method according to claim 3, characterized in that, The method comprises the following specific operation steps: The method comprises the following specific operation steps: S1, tetraphenylporphyrin-tetraphenylstyrene-bromine alkyl fluorene conjugated oligomer preparation: tetraphenylstyrene borate, halogenated tetraphenylporphyrin, halogenated bromine alkyl fluorene, anhydrous potassium carbonate and catalyst Pd(PPh3)4 are weighed according to the proportion of substances, the air is replaced with inert gas, then the mixed solution of toluene and water is added under inert gas atmosphere to form a reaction solution, the reaction solution is heated to 70-90℃, and reacted for 36-55 h, then cooled to room temperature, diluted with dichloromethane, washed with deionized water, dried with anhydrous sodium sulfate, filtered, rotary evaporated to remove the solvent, the crude product is dissolved in dichloromethane, then dropped into a large amount of methanol, centrifuged, the precipitate is washed with methanol, and vacuum dried to obtain tetraphenylporphyrin-tetraphenylstyrene-bromine alkyl fluorene conjugated oligomer; S2, tetraphenylporphyrin-tetraphenylstyrene-quaternary ammonium fluorene conjugated oligomer preparation: the tetraphenylporphyrin-tetraphenylstyrene-bromine alkyl fluorene conjugated oligomer prepared in step S1 is weighed, dissolved in tetrahydrofuran, 50% trimethylamine is added, reacted at room temperature for 6-18 h, dissolved in MeOH, and then the remaining 50% trimethylamine is added, reacted for 12-48 h, rotary evaporated to remove the solvent, dissolved in tetrahydrofuran, added with acetone, centrifuged, and obtained tetraphenylporphyrin-tetraphenylstyrene-quaternary ammonium fluorene conjugated oligomer; S3, mixed conjugated oligomer solution preparation: the tetraphenylporphyrin-tetraphenylstyrene-quaternary ammonium fluorene conjugated oligomer prepared in step S2 is dissolved in N,N-dimethylformamide, then methanol is added; a surfactant is dissolved in methanol, and the two solutions are mixed to obtain a mixed conjugated oligomer solution with a concentration of 100-200 ppm; S4, nanomaterial preparation: the mixed conjugated oligomer solution prepared in step S3 is quickly injected into deionized water under ultrasonic condition, ultrasonically treated, and then rotary evaporated to remove the solvent, thereby obtaining a small-size porphyrin-based AIE conjugated oligomer nanomaterial.

7. The preparation method according to claim 6, characterized in that, In step S1, the volume ratio of toluene to deionized water in the mixed solution of toluene and water is 1:0.2-0.8; and the concentration of tetraphenylstyrene borate in the reaction solution is 4.0-20.0 mmol / L.

8. The production method according to claim 6 or 7, characterized by, In step S2, the amount of substance of trimethylamine is 20-100 times that of the tetraphenylporphyrin-tetraphenylstyrene-bromine alkyl fluorene conjugated oligomer obtained in step S1; and the concentration of the tetraphenylporphyrin-tetraphenylstyrene-bromine alkyl fluorene conjugated oligomer in tetrahydrofuran is 10-40 mg / mL.

9. The production method according to claim 6 or 7, characterized by, In step S3, the surfactant is selected from one of mPEG-COOH-350, DSPE-PEG-2000, HOOC-PEG-COOH and F127; the mass ratio of the surfactant to the conjugated polymer is 10-25:1, and the concentration of the surfactant solution is 0.001-0.00125 g / mL; and in step S4, the ultrasonic treatment time is 2-12 h.

Images