Small-size porphyrinyl AIE conjugated oligomer nanometer material and preparation method thereof

Abstract

The invention relates to a small-size porphyrinyl AIE conjugated oligomer nano material and a preparation method thereof. The small-size porphyrinyl AIE conjugated oligomer nano material contains a tetraphenyl porphyrin-tetraphenyl ethylene-quaternary ammonium fluorene group. The invention also comprises a preparation method of the small-size conjugated oligomer nanometer material. The small-size conjugated oligomer nanoparticles have water-soluble quaternary ammonium fluorene with positive charges, a tetraphenyl porphyrin group with near-infrared characteristics and a tetraphenyl ethylene group with an AIE effect. Porphyrin groups have extremely high rigidity and hydrophobicity, and introduction of characteristic quaternary ammonium fluorene into a conjugated main chain is beneficial to improvement of hydrophilicity of the conjugated main chain and formation of small-size nanoparticles; due to the introduction of the tetraphenyl ethylene group with the AIE effect, the AIE effect of the novel conjugated oligomer and the modulation of the luminescence property of the small-size nanoparticle probe can be realized. The average particle size of the small-size porphyrinyl AIE conjugated oligomer nano-material is about 4.64 nm, and the sensitivity and the specificity of fluorescence analysis of the conjugated oligomer nano-material can be improved.

Description

Technical Field

[0001] The invention relates to a conjugated oligomer nano material and a synthesis method thereof, in particular to a small-size conjugated oligomer nano material and a synthesis method thereof. Background Art

[0002] Conjugated polymers (CPs) are organic macromolecules whose delocalized π electron system can absorb light energy and convert it into fluorescence, heat and other energy. However, due to their hydrophobic organic structure, they have 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 biosensing, cell imaging, phototherapy and drug delivery because of their good photostability, high molar absorption coefficient and good biocompatibility (Bioorganic Chemistry 145 (2024) 107188, Biomacromolecules 2023, 24, 1943-1979). Conjugated oligomer nanoparticles (CONs), as analogs of conjugated polymer nanoparticles, have high fluorescence quantum yield and stability. Because they are mostly prepared from oligomers with smaller molecular size and precise structure, compared with conjugated polymers, conjugated oligomers are easier to regulate and purify. Due to their excellent properties, they are widely used in fluorescence detection and imaging, cancer cell targeted identification, photodynamic therapy (PDT) and chemotherapy (ACS Appl. Bio Mater. 2019, 2, 1340-1347, CN113069557B, CN117986275A).

[0003] The AIE (aggregation-induced emission) phenomenon overcomes the previous shortcoming that fluorophores are easily quenched when aggregated (Chem. Commun., 2001, 1740–1741). AIE polymers have the advantages of high aggregate and solid-state emission efficiency, multifunctionality and good signal amplification effect, and have been widely used in optoelectronic devices, chemical / biosensors and biomedicine (Progress in Polymer Science 100 (2020) 101176).

[0004] Porphyrin and its derivatives are called life pigments. They have excellent light-harvesting ability and near-infrared emission characteristics, so they are widely used in photovoltaics, biomedicine, bio / chemical sensing, photocatalytic hydrogen evolution and carbon dioxide reduction (Aggregate 2023, e330). Porphyrin is a heterocyclic aromatic organic compound. Due to its strong π-π 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 and can form water-soluble sensing materials, which is conducive to the construction of new "amphiphilic" oligomers, and then form new small-size (~1-9nm) conjugated oligomer nanoprobes with specificity and high sensitivity (Chem. Soc. Rev., 2022, 51, 9917–

[0006] 9932).

[0007] Existing conjugated polymer nanomaterials often experience aggregation-induced quenching in water due to their large conjugated structure, thereby reducing the fluorescence quantum yield; at the same time, because conjugated polymers have a large molecular weight, they tend to form larger nanospheres when preparing nanoparticles, which reduces the sensitivity of nanoprobes; in addition, most existing nanomaterials emit in the ultraviolet-visible light region, and there will be a lot of background interference when used in biological imaging, which limits their scope of application. 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 an AIE effect. The small-sized nanoparticle material made from it has a particle size of only 1-9nm; the conjugated oligomer has a strong fluorescence emission phenomenon in the near-infrared range (660nm~700nm).

[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 nanomaterial.

[0010] The technical solution adopted by the present invention to solve the technical problem is: a small-sized conjugated oligomer nanomaterial is a conjugated oligomer containing tetraphenylporphyrin-tetraphenylethylene-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 tetraphenylporphyrin includes a variety of metals that can enter the central position of the porphyrin.

[0014] As Zn 2+ 、Eu 2+ wait.

[0015] The technical solution adopted by the present invention to further solve the technical problem is a preparation method of the small-sized porphyrin-based AIE conjugated oligomer nanomaterial, comprising the following steps: using halogenated bromoalkylfluorene, halogenated tetraphenylporphyrin and tetraphenylethylene borate as raw material monomers, under the action of a catalyst and a basic salt, in a solvent, through a Suzuki coupling polycondensation reaction, a conjugated oligomer of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene is synthesized, wherein the chain length of the alkane on the raw material halogenated bromoalkylfluorene is changed to adjust its structure, and then a conjugated oligomer containing tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene is obtained through a quaternization reaction with trimethylamine; then a trace amount of N,N-dimethylformamide is used to dissolve, 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 to 200 ppm, and the obtained mixed conjugated oligomer solution is injected into water, ultrasonicated, and then rotary evaporated to remove the solvent to obtain 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 to 90°C, preferably 75 to 85°C, and more preferably 80°C.

[0018] Furthermore, the polycondensation reaction time is 36-55h, preferably 40-50h, more preferably 48h.

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

[0020] Furthermore, the molar ratio of the raw material monomers tetraphenylethylene borate (n), halogenated tetraphenylporphyrin (x) and brominated alkylfluorene (y) is n:(x+y) or n:(2x+y) is 1.0:1.0-1.2.

[0021] Furthermore, the ratio of the raw material monomers halogenated tetraphenylporphyrin (x) and halogenated brominated alkylfluorene (y) is regulated according to the ratio of functional groups, and is x+y=1 or 2x+y=1.

[0022] Furthermore, the alkanes of different chain lengths on the raw material monomer halobromoalkylfluorene 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 tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer; and the volume ratio of tetrahydrofuran to methanol is 1:0.25 to 1.

[0024] The present invention provides a method for preparing a small-sized porphyrin-based AIE conjugated oligomer nanomaterial, and the specific operating steps are:

[0025] S1. Preparation of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer: tetraphenylethylene borate, halogenated tetraphenylporphyrin, halogenated bromoalkylfluorene, anhydrous potassium carbonate and catalyst Pd(PPh3)4 are weighed according to the ratio of the amount of substances, the air is replaced by an inert gas, and then a mixed solution of toluene and water (deoxygenated in advance) is added under an inert gas atmosphere to form a reaction solution, the reaction solution is heated to 70-90°C (preferably 75-85°C, more preferably 80°C), reacted for 36-55h (preferably 40-50h, more preferably 48h), cooled to room temperature, diluted with dichloromethane, washed with deionized water, extracted and separated, dried with anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation, the crude product was dissolved in dichloromethane, and then methanol was added dropwise, centrifuged, the precipitate was washed with methanol, and vacuum dried to obtain tetraphenylporphyrin-tetraphenylethylene-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 6-18h (preferably 10-15h, more preferably 12h), add MeOH to dissolve it, add the remaining 50% trimethylamine, react for 12-48h (preferably 18-40h, more preferably 22-30h, further preferably 24h), remove the solvent by rotary evaporation, add tetrahydrofuran to dissolve it, add acetone, and centrifuge to obtain the tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene conjugated oligomer;

[0027] S3, preparation of mixed conjugated oligomer solution: dissolving the tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene conjugated oligomer obtained in step S2 using N,N-dimethylformamide, and then adding methanol; dissolving a surfactant in methanol, mixing the above two solutions, and obtaining a mixed conjugated oligomer solution with a concentration of 100 to 200 ppm;

[0028] S4. Preparation of nanoparticle material: The mixed conjugated oligomer solution prepared in step S3 is rapidly injected into deionized water under ultrasonic conditions, ultrasonicated, and then rotary evaporated to remove the solvent to obtain a small-sized porphyrin-based AIE conjugated oligomer nanomaterial.

[0029] The small-sized porphyrin-based AIE conjugated oligomer nanomaterial prepared by the present invention has a particle size of less than 9nm and a relatively uniform particle size. It is a new type of AIE nanoparticle material. It has excellent water dispersibility and is easily soluble in organic solvents such as N,N-dimethylformamide, dimethyl sulfoxide and methanol. It has a wide range of applications and is suitable for use in different detection systems.

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

[0031] Furthermore, in step S1, the concentration of tetraphenylethylene borate in the reaction solution is 4.0 to 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-tetraphenylethylene-bromoalkylfluorene obtained in step S1.

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

[0034] In step S3, if the concentration of the mixed conjugated oligomer solution is too low, it will be difficult for the conjugated oligomers to agglomerate to form nanoparticles, and the product yield will be low; if the concentration is too high, the conjugated oligomers will be more likely to agglomerate, resulting in larger particle sizes of the formed nanoparticles.

[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 assist in dissolving the conjugated oligomer, and the conjugated oligomer can be azeotropically removed with water during rotary evaporation.

[0040] Furthermore, in step S4, the ultrasonication time is 2 to 12 hours.

[0041] In steps S1 and S2, the reaction conditions such as temperature and time will affect the degree of polymerization of the conjugated oligomer and should therefore 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, the temperature is raised to 140 to 150°C, and the reaction is carried out under this condition for 15 to 20 minutes to obtain a bright yellow liquid, and then hydrazine hydrate is slowly dripped into it at a speed of 0.5 to 1.5 mL / min and a mass ratio of hydrazine hydrate to DMSO of 1:60 to 100 under low-speed stirring. The reaction liquid turns into wine red. After the addition is completed, stirring is stopped, the mixture is cooled, and filtered. The crude product is washed 5 times with anhydrous ethanol and 3 times with ether to obtain the golden solid catalyst Pd(PPh3)4. The catalyst is stored in a vacuum at -5°C.

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

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

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

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

[0047] The beneficial effects of the present invention are:

[0048] (1) The conjugated oligomer obtained by the present invention has a low degree of polymerization and a small molecular weight, and is easy to form a new type of nanoparticles with a small particle size and excellent performance. The conjugated oligomer contains a quaternary ammonium group fluorene and a tetraphenylethylene group. The tetraphenylethylene group has an AIE effect, and the quaternary ammonium group is water-soluble, which is conducive to the formation of water-soluble AIE nanoparticles; at the same time, the tetraphenylethylene group and the quaternary ammonium fluorene group of the conjugated oligomer have strong fluorescence emission. The quaternary ammonium group is positively charged and is easy to agglomerate with the negatively charged group through electrostatic action, which is conducive to sensitive detection and imaging of substances in aqueous solutions and cell environments;

[0049] (2) The present invention successfully synthesizes a conjugated oligomer with a low degree of polymerization through a Suzuki coupling polycondensation reaction. By controlling the molar ratio of tetraphenylethylene borate, halogenated tetraphenylporphyrin, and halogenated quaternary ammonium fluorene, novel conjugated oligomers with different proportions are 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 oligomer, and the present invention also appropriately controls them.

[0050] (3) The present invention successfully prepared novel AIE nanoparticles with good dispersibility and small particle size (<9 nm) by controlling the concentration of the conjugated oligomer solution and selecting the surfactant using an improved nanoprecipitation method. The 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, a 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, with low investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a hydrogen nuclear magnetic resonance spectrum of the conjugated oligomer synthesized in Example 1 of the method of the present invention;

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

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

[0055] Figure 4 are the ultraviolet absorption spectrum and fluorescence spectrum of the conjugated oligomer synthesized in Example 1;

[0056] Figure 5The fluorescence spectrum of the conjugated oligomer synthesized in Example 1 and the fluorescence spectrum of the nanoparticles prepared in Example 2 using the conjugated oligomer synthesized in Example 1;

[0057] Figure 6 The fluorescence spectra of the conjugated oligomer synthesized in Example 1 at different volume ratios of H2O / DMF and the fluorescence intensity variation at 505nm;

[0058] Figure 7 It is a schematic diagram of the process of preparing small-sized porphyrin-based AIE conjugated oligomer nanomaterials in Example 2 of the present invention. DETAILED DESCRIPTION

[0059] The present invention is further described below in conjunction with embodiments and drawings.

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

[0061] Reference Example 1: Synthesis of the catalyst tetrakis(triphenylphosphine)palladium 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), and heated to 140-160°C under nitrogen protection with stirring. After the reaction is kept warm for 12-18 minutes, the color of the solution changes from yellow to red. Hydrazine hydrate is then 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, allowed to stand, cooled, filtered, and the filter residue is washed with ethanol for ≥4 times and with ether for ≥2 times to obtain the 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] Add 165 mL of mixed solution (CH3COOH:H2O:H2SO4, V / V, 50:4:1) to a 250 mL three-necked flask, heat the solution to 80°C, then add fluorene (2.54 g, 15 mmol), KIO3 (1.28 g, 6 mmol), I2 (4.1 g, 16.2 mmol), reflux for 10 h, cool the solution to room temperature, filter, and wash the precipitate with 100 mL of deionized water and 200 mL of 2M Na2CO3 solution. Recrystallize the crude product in dichloromethane and dry to obtain 2,7-diiodofluorene as a white solid.

[0065] 30 mL of 50% KOH solution was added to a 100 mL three-necked flask, 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), and the mixture was reacted at 75 ° C for 15 min, and then the mixture was quickly 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, and then dried with anhydrous sodium sulfate, filtered, and the organic solvent was removed by vacuum distillation. Then, column chromatography (petroleum ether: dichloromethane, V / V, 35:1) was used to obtain a white solid 2,7-diiodo-9,9-di(6'-bromohexyl)fluorene.

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

[0067] The synthetic reaction formula is as follows:

[0068]

[0069] Synthesis reaction formula IX shows the synthesis steps of the conjugated oligomer of this embodiment, and the specific operation method includes the following steps:

[0070] (1) In a 50 mL round-bottom flask, 1,2-diphenyl-1,2-di(4-pinacolyl ester phenyl)ethylene (0.2 mmol, 120.5 mg), 2,7-diiodo-9,9-di(6'-bromohexyl)fluorene (0.18 mmol, 133.9 mg), 5,10,15,20-tetrakis(4-bromophenyl)porphyrin (0.01 mmol, 9.8 mg), Pd(PPh3)4 (0.02 mmol, 23.1 mg) were added. g), tetrabutylammonium bromide (0.02mmol, 6.6mg) and anhydrous potassium carbonate (24.8mmol, 3.43g), add 9mL water and 14mL toluene, react for 48h at 80℃ under Ar atmosphere, stop the reaction, cool the reaction mixture to room temperature, add DCM (50mL) to dilute, wash with deionized water (50mL×3), extract and separate, dry with anhydrous sodium sulfate, filter, and remove the solvent by rotary evaporation. Dissolve the crude product in 1mL DCM, slowly drop 50mL of methanol, and centrifuge to obtain a light brown solid;

[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 of THF and 0.5 mL of trimethylamine, react at 25° C. for 12 h, add 2 mL of methanol, ultrasonically dissolve the black precipitate on the wall of the flask, then add 0.5 mL of trimethylamine, and reflux at 25° C. for another 24 h. After the reaction is completed, remove the solvent and excess trimethylamine by rotary evaporation, add 1 mL of THF and 50 mL of acetone for recrystallization, and centrifuge to obtain a dark brown target product, a conjugated oligomer solid (FNTT).

[0072] NMR characterization: reference Figure 1 , Figure 2 A certain amount of the conjugated oligomer (FNTT) was weighed and dissolved in 600 μL of deuterated dimethyl sulfoxide reagent, and then the solution was transferred to a nuclear magnetic resonance tube for nuclear magnetic resonance characterization. The hydrogen spectrum was as follows: Figure 1 and Figure 2 The specific data are 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 8.01ppm are the proton hydrogens on the benzene ring in tetraphenylporphyrin, the 6 proton hydrogens at 7.68ppm-7.61ppm are the 6 proton hydrogens on the benzene ring in fluorene, the 18 proton hydrogens at 7.26ppm-7.05ppm are the proton hydrogens on the benzene ring in tetraphenylethylene, the proton hydrogens at 2.95ppm are the 18 proton hydrogens of the quaternary ammonium salt and the proton hydrogens of the two methylene groups connected to the quaternary ammonium group, and the 20 proton hydrogens at 2.10ppm, 2.10ppm, 1.44ppm and 1.02ppm are the proton hydrogens of the alkyl chain connected to fluorene.

[0073] Example 2: Example of a method for preparing a small-sized porphyrin-based AIE conjugated oligomer nanomaterial of the present invention

[0074] (1) 1.0 mg of the conjugated oligomer prepared in Example 1 was weighed and dissolved in 20 μL of DMF, and then 5 mL of MeOH solution was added to prepare a 200 ppm solution;

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

[0076] (3) The solutions prepared in steps (1) and (2) were mixed uniformly to form a 100 ppm mixed solution. The mixed solution was rapidly injected into 20 mL of deionized water under ultrasonic conditions, ultrasonicated for 12 h, and the solvent was removed by rotary evaporation (assuming that the energy of water was not lost) to obtain a small-sized nanoparticle material with a size of about 4.64 nm.

[0077] The TEM image of the small-sized porphyrin-based AIE conjugated oligomer nanomaterial prepared in this example is shown in FIG. Figure 2 As shown in the figure, the particle size distribution is relatively uniform, and all of them are small-sized nanoparticles with a particle size of about 1 to 9 nm. They have excellent water dispersibility in aqueous solution. Figure 3 As shown, the average diameter of the nanoparticles is about 4.64 nm.

[0078] Figure 4 It is the ultraviolet absorption spectrum and fluorescence spectrum of the conjugated oligomer synthesized in Example 1; in the ultraviolet absorption spectrum, 361nm belongs to the peak of quaternary ammonium fluorene, 415nm belongs to the s band of porphyrin, and the Q band is not obvious because the proportion of porphyrin is too small; in the fluorescence spectrum, 505nm belongs to the characteristic peak of quaternary ammonium fluorene, and 660nm reflects the near-infrared characteristic peak of porphyrin.

[0079] Transfer 1 mL of the nanoparticle solution to a fluorescence cuvette and measure its fluorescence spectrum. Figure 5 As shown, the polymer nanoparticle solution has a maximum emission peak at 505 nm.

[0080] Figure 6 It is the fluorescence spectrum of the conjugated oligomer synthesized in Example 1 at different volume ratios of H2O / DMF and the fluorescence intensity change diagram at 505nm; it can be seen from the figure that with the increase of water volume, the fluorescence at 505nm gradually increases, which proves that the synthesized conjugated oligomer has AIE effect.

[0081] Figure 7 This is a schematic diagram of the mechanism of the small-sized porphyrin-based AIE conjugated oligomer nanomaterial prepared in Example 2. The conjugated oligomer FNTT wrapped by the surfactant mPEG-COOH-350 is dissolved in methanol, then injected into deionized water under ultrasonic conditions and ultrasonicated for 2 to 12 hours, and then the volatile organic solvent methanol is removed, and small-sized conjugated oligomer nanoparticles (FNTTNPs, ~4.64nm) are formed. And at an excitation wavelength of 427nm, the FNTT nanoparticles can emit peaks of 505nm and 660nm.

Claims

1. A small-sized porphyrin-based AIE conjugated oligomer nanomaterial, characterized in that: The chemical structural formulas of the conjugated oligomers are shown in the following formulas I to IV: In Formula I and Formula III, 2x+y=1; in Formula II and Formula IV, x+y=1.

2. The small-sized porphyrin-based AIE conjugated oligomer nanomaterial according to claim 1, characterized in that: The metal M in the tetraphenylporphyrin is Zn 2+ or Eu 2+ .

3. A method for preparing the small-sized porphyrin-based AIE conjugated oligomer nanomaterial as claimed in claim 1, characterized in that: The following steps are involved: The method uses halogenated bromoalkylfluorene, halogenated tetraphenylporphyrin and tetraphenylethylene borate as raw material monomers, and synthesizes a conjugated oligomer of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene through a Suzuki coupling polycondensation reaction in a solvent under the action of a catalyst and a basic salt, wherein the chain length of the alkane on the raw material halogenated bromoalkylfluorene is changed to adjust its structure, and then a conjugated oligomer containing tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene is obtained through a quaternization reaction with trimethylamine; then N,N-dimethylformamide is used to dissolve the conjugated oligomer, and 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 to 200 ppm; the obtained mixed conjugated oligomer solution is injected into water, ultrasonicated, and then rotary evaporated to remove the solvent to obtain the target product.

4. The preparation method according to claim 3, characterized in that: The catalyst used in the Suzuki coupling polycondensation reaction is Pd(PPh3)4; the basic salt used is anhydrous potassium carbonate; the temperature of the coupling polycondensation reaction is 70-90°C, and the reaction time is 36-60h; the amount of the Pd(PPh3)4 is 5%-10% of the amount of tetraphenylethylene borate; the amount of the anhydrous potassium carbonate is 10%-13% of the amount of tetraphenylethylene borate; the molar ratio of the tetraphenylethylene borate n to the halogenated tetraphenylporphyrin x and the halogenated bromoalkylfluorene y is n:x+y or n:2x+y of 1:1-1.2, and the ratio of the halogenated tetraphenylporphyrin and the halogenated bromoalkylfluorene is regulated according to the amount of different substances; the halogenated alkanes of different chain lengths in the quaternary ammonium fluorene group are 1,6-dibromopropane, 1,6-dibromobutane, 1,6-dibromopentane or 1,6-dibromohexane.

5. The preparation method according to claim 4, characterized in that: The amine used in the quaternization reaction is trimethylamine; the solvents are tetrahydrofuran and methanol; the amount of trimethylamine is 20 to 100 times the amount of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer; and the ratio of tetrahydrofuran to methanol is 1:0.25 to 1.

6. The preparation method according to claim 5, characterized in that: The temperature of the quaternization reaction is 0°C to 30°C.

7. The preparation method according to claim 4, characterized in that: The specific steps are as follows: S1. Preparation of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer: tetraphenylethylene borate, halogenated tetraphenylporphyrin, halogenated bromoalkylfluorene, anhydrous potassium carbonate and catalyst Pd(PPh3)4 are weighed according to the ratio of the amount of substances, the air is replaced by an inert gas, and then a mixed solution of toluene and water is added under an inert gas atmosphere to form a reaction solution, the reaction solution is heated to 70-90°C, preferably 75-85°C, more preferably 80°C, reacted for 36-55h, preferably 40-50h, more preferably 48h, cooled to room temperature, diluted with dichloromethane, washed with deionized water, extracted and separated, dried with anhydrous sodium sulfate, filtered, and rotary evaporated to remove the solvent, dissolved the crude product in dichloromethane, and then dropped a large amount of methanol, centrifuged, washed the precipitate with methanol, and vacuum dried to obtain tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer; 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 6-18h, preferably 10-15h, more preferably 12h, add MeOH to dissolve, add the remaining 50% trimethylamine, react for 12-48h, preferably 18-40h, more preferably 22-30h, further preferably 24h, remove the solvent by rotary evaporation, add tetrahydrofuran to dissolve, add acetone, centrifuge to obtain tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene conjugated oligomer; S3, preparation of mixed conjugated oligomer solution: dissolving the tetraphenylporphyrin-tetraphenylethylene-quaternary ammonium fluorene conjugated oligomer obtained in step S2 using N,N-dimethylformamide, and then adding methanol; dissolving a surfactant in methanol, mixing the above two solutions, and obtaining a mixed conjugated oligomer solution with a concentration of 100 to 200 ppm; S4. Preparation of nanomaterials: The mixed conjugated oligomer solution prepared in step S3 is rapidly injected into deionized water under ultrasonic conditions, ultrasonicated, and then rotary evaporated to remove the solvent to obtain small-sized porphyrin-based AIE conjugated oligomer nanomaterials.

8. The preparation method according to claim 7, characterized in that: In step S1, in the mixed solution of toluene and water, the volume ratio of toluene to deionized water is 1:0.2-0.8, preferably 1:0.6; in the reaction solution, the concentration of tetraphenylethylene borate is 4.0-20.0 mmol / L, preferably 8.0 mmol / L.

9. The preparation method according to claim 7 or 8, characterized in that: In step S2, the amount of trimethylamine is 20 to 100 times the amount of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer obtained in step S1; the concentration of tetraphenylporphyrin-tetraphenylethylene-bromoalkylfluorene conjugated oligomer in tetrahydrofuran is 10 to 40 mg / mL.

10. The preparation method according to claim 7 or 8, characterized in that: 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 to 25:1, and the concentration of the surfactant solution is 0.001 to 0.00125 g / mL; In step S4, the ultrasonication time is 2 to 12 hours.

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