Aggregation-induced luminescent compound, and supramolecular polymerized fluorescent nano-material and preparation method therefor

Abstract

The present invention relates to an aggregation-induced luminescent compound, and a supramolecular polymerized fluorescent nano-material and a preparation method therefor. The preparation method for t

Description

[0001] The present disclosure belongs to the field of medical material, and in particular relates to an aggregation-induced emission compound, and a supramolecular polymerized fluorescent nano-material and a preparation method thereof. BACKGROUND ART

[0002] Supramolecular chemistry is the science of studying the formation of ordered aggregates by multiple simple small molecules through intermolecular interactions. Usually, supramolecular emission materials are constructed from molecules with organic conjugated planar(s), but due to ti-k interaction, the formed supramolecular materials have disadvantages of low luminous efficiency and even fluorescence quenching. In 2001, Academician Tang Benzhong first discovered molecules with "Aggregation-Induced Emission (AIE)" property. The fluorescence intensity of these molecules in the free state or monomolecular state is very weak, or even does not emit fluorescence. In the aggregated state or solid state, it has obvious fluorescence intensity. Therefore, binding AIE molecules and supramolecular materials solves the fluorescence quenching problem of traditional supramolecular emission materials.

[0003] In addition, most AIE molecules are usually %-conjugated and hydrophobic, and only soluble in organic solvents, which makes them unsuitable for biological applications. The preparation methods of AIE dots can be divided into two categories. The first category is the earliest carrier-free method, and it is also the simplest one, i.e., generating nano-dots by solvent exchange, such as adding a solution of the sample in a good solvent into a poor solvent that is miscible with the good solvent under stirring. The second category is to use physical wrapping, in which AIEgen is wrapped by amphiphilic molecules to improve size control and colloid stability. However, under such circumstances, AIEgen is easy to leak, leading to the change of optical properties. 29 11 24 SUMMARY

[0004] The present disclosure aims to provide an emission compound, a supramolecular polymerized fluorescent nano-material and a preparation method thereof. On the basis of compounds with aggregation-induced emission (AIE) property, AIE molecules are covalently / non-covalently introduced into a supramolecular system, and spontaneous assembly occurs to form nanoparticles by hydrophilic-hydrophobic interactions between molecules, and finally compact and stable AIE dots are generated by photo-crosslinking.

[0005] In order to avoid leakage, AIE molecules can be covalently conjugated with ions or hydrophilic chains to generate water-soluble AIE analogues or amphiphilic AIE macromolecules, which then self-assemble into AIE fluorescent supramolecular polymers through hydrophilic-hydrophobic interactions between molecules.

[0006] In the present disclosure, by utilizing the excellent self-assembly performance of diacetylene, AIE small molecules are introduced covalently / non-covalently into the polydiacetylene supramolecular system, and spontaneous assembly occurs to form aggregation-induced emission supramolecular polymers through hydrophilic-hydrophobic interactions between molecules. The technical solutions make it possible to solve the aggregation-caused quenching problem of fluorescence for AIE small molecules and endow them with good water solubility. In addition, the polymerization of diacetylene makes the aggregate structure rigid, which could prevent the leakage of fluorescent dyes, thus developing a new nanostructure with an identified structure.

[0007] The objects of the present disclosure can be achieved by the following technical solution:

[0008] The first object of the present disclosure is to claim an aggregation-induced emission compound, which has a molecular structural formula of

[0009] wherein D moiety is triphenylamine or diphenylamine with an electron donor, having a structural formula of wherein Ri is phenyl or hydrogen, R2 is hydrogen or boronic, and R3 is selected from the group consisting of hydrogen, hydroxyl, and amino.

[0010] In some embodiments, Ri, R2 and R3 each are hydrogen.

[0011] The second object of the present disclosure is to claim a method for preparing a supramolecular polymerized fluorescent nano-material, including the following steps: Al: covalently bonding compound 3 with 10,12-Pentacosadiynoic acid (PCDA) to obtain the above-mentioned aggregation-induced emission compound; A2: dissolving the aggregation-induced emission compound obtained in step Al in dichloromethane or chloroform to obtain a solution I; A3: dissolving PCDAin dichloromethane or chloroform to obtain a solution II; A4: preparing a precursor of the supramolecular polymerized fluorescent nanomaterial from the solution I obtained in step A2 and the solution II obtained in step A3 by a film hydration method; and A5: cooling the precursor obtained in step A4 and staying overnight in a refrigerator at a temperature of 2-6 °C to allow the precursor to spontaneously assemble to obtain nanoparticles, and before using, irradiating the nanoparticles with a 254 nm ultra-violet (UV) lamp to allow the nanoparticles to polymerize to obtain the supramolecular polymerized fluorescent nano-material; wherein the compound 3 has a structural formula of . OH

[0012] In some embodiments, the aggregation-induced emission compound is prepared by a process including the following steps: Bl: dissolving the compound 3, 4-Dimethylaminopyridine (DMAP) and N, N'-dicyclohexylcarbodiimide (DCC) in an organic solvent, stirring for dissolution, slowly adding a PCDA solution thereto, and stirring for reaction in absence of light to obtain a mixed solution of reaction products; and B2: evaporating out the organic solvent from the mixed solution of reaction products, drying, dissolving a resulting residue in di chloromethane to obtain a solution III, extracting the solution III with a supersaturated NaHCOa solution to remove DCC, adding sodium sulfate anhydrous to remove water to obtain a crude product, and purifying the crude product to obtain the aggregation-induced emission compound.

[0013] In some embodiments, a ratio of the compound 3, DMAP and DCC in step Bl is 151 mg: 47.14 mg: 100 mg.

[0014] In some embodiments, the compound 3 is prepared by a process including the following steps: Cl: adding compound 2, 4-(diphenylamino)phenylboronic acid and 29 11 24 tetrakis(triphenylphosphine)palladium into a reactor, adding tetrahydrofuran (THF), redistilled dimethylformamide (DMF) and a K2CO3 solution thereto, and uniformly mixing to obtain a clear and transparent solution; C2: vacuumizing the clear and transparent solution obtained in step Cl, performing reaction under a protection of an inert gas at a temperature of 80 °C, monitoring the reaction by thin layer chromatography (TLC) during the reaction, stopping heating after the reaction is complete, and naturally cooling a resulting reaction system to room temperature to obtain a layered liquid with a tangerine fluorescence upper layer and a colorless lower layer; and C3: removing solvent from the layered liquid obtained in step C2, extracting with dichloromethane (DCM), washing with a saturated sodium chloride solution, and purifying with a 100-200 mesh silica gel chromatographic column to obtain a pure yellow product, i.e., the compound 3;

[0015] wherein the compound 2 has a structural formula of OH r. O N O Br

[0016] In some embodiments, a ratio of the compound 2, 4- (diphenylamino)phenylboronic acid, and tetrakis(triphenylphosphine)palladium is 300 mg: 259 mg: 47 mg.

[0017] In some embodiments, the compound 2 is prepared by a process including the following steps: DI: adding 4-bromo-l,8-naphthalic anhydride, 3-aminophenol and acetic acid to a reactor, subjecting a resulting mixture to reaction under a protection of nitrogen at a temperature of 130 °C, monitoring the reaction by TLC during the reaction, adding water 29 11 24 to dissolve the acetic acid after the reaction is complete, leaving a resulting system to stand, filtering to obtain a pale yellow solid, and recrystallizing with acetic acid to obtain a pure yellow solid powder, namely the compound 2

[0018] In some embodiments, a ratio of 4-bromo-l,8-naphthalic anhydride, 3-aminophenol, and acetic acid is 2.00 g: 1.023 g: 10 mL.

[0019] As the core concept of the present technical solution, by utilizing the excellent self-assembly performance of diacetylene, AIE small molecules are covalently / non-covalently introduced into the polydiacetylene supramolecular system, and spontaneous assembly occurs to form aggregation-induced emission supramolecular polymers through intermolecular hydrophilic-hydrophobic interactions. The technical solutions make it possible to solve the aggregation-caused quenching problem of fluorescence for AIE small molecules and endow aggregation-induced emission supramolecular polymers with good water solubility. In addition, the polymerization of diacetylene makes the aggregate structure rigid, which could prevent the leakage of fluorescent dyes, thus developing a new nanostructure with an identified structure.

[0020] Comparing with the prior art, some embodiments of the present disclosure have the following technical advantages. 1. In the compound prepared in the present disclosure, 4-site C of naphthalimide is connected with strong electron-donating group, which could improve the fluorescence quantum efficiency and is conducive to the shift of Stokes shift conversion to infrared wavelength region. 2. The aggregation-induced emission nano-material of the present disclosure exhibits a large Stokes shift, and can be applied to cell imaging to avoid the influence of background fluorescence. 3. The present disclosure utilizes nano-precipitation and subsequent photocrosslinking to prepare AIE dots with high brightness and surface functionalization. 4. Comparing with traditional fluorescent materials such as organic dyes, fluorescent proteins and inorganic quantum dots, this kind of emission materials has the advantage of high fluorescence intensity at an aggregated state. 29 11 24 BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 shows an 'H nuclear magnetic resonance f'H-NMR.) spectrum of the compound 4 synthesized in step 1 of Example 1.

[0022] FIG. 2 shows a UV absorption spectrum of the compound 4 synthesized in step 3 of Example 1.

[0023] FIG. 3 shows a fluorescence emission spectrum of the compound 4 synthesized in step 3 of Example 1.

[0024] FIG. 4 shows a scanning electron microscope (SEM) image of the compound 4 powder synthesized in step 3 of Example 1.

[0025] FIG. 5 shows an AIE property of the NT-DA in Example 1.

[0026] FIG. 6 shows a high-resolution mass spectrum of the compound 4 synthesized in step 3 of Example 1.

[0027] FIG. 7 shows a particle size distribution diagram of supramolecular polymerized fluorescent nanoparticles formed in step 4 of Example 1.

[0028] FIG. 8 shows an SEM image of supramolecular polymerized fluorescent nanoparticles formed in step 4 of Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present disclosure is described in detail below in conjunction with drawings and specific examples.

[0030] Example 1

[0031] In this example, the synthesis process was performed according to the following flowchart.

[0032] Step 1, synthesis of compound 2: 29 11 24

[0033] 4-bromo-1,8-naphthalic anhydride (2.00 g, 7.22 mmol), 3-aminophenol (1.023 g, 9.39 mmol) and 10 mL of acetic acid were added into a 100-mL three-necked flask. Under the protection of nitrogen, the temperature was gradually raised to 130 °C, and a clear brown solution was obtained by stirring. The reaction was performed for 4.5 hours and was monitored by TLC (DCM: EA = 10: 1 ,V / V). After the reaction was completed, the resulting system was naturally cooled and a yellow solid was precipitated. 20 mL of water was added to the flask to dissolve acetic acid. The resulting system was left to stand and filtered on a suction filter to obtain 2.31 g of a pale yellow solid. The pale yellow solid was recrystallized with acetic acid to obtain a pure yellow solid powder.

[0034] Step 2, synthesis of compound 3:

[0035] At room temperature, the compound 2 (300 mg, 0.815 mmol), 4-(diphenylamino)phenylboronic acid (259 mg, 0.8967 mmol) and tetrakis(triphenylphosphine)palladium (47 mg, 0.04076 mmol) were placed in a 100mL reaction tube, and then 10 mL THF, 2.5 mL re-distilled DMF and a K2CO3 solution (1.12 g / 5 mL water) were added to completely dissolve solid compounds to obtain a clear and transparent solution. The obtained clear and transparent solution was vacuumized. Under the protection of gas, the reaction was started, and the temperature was gradually raised to 80 °C. During the reaction, tangerine fluorescence was observed in the clear and transparent solution. The reaction was monitored by TLC (DCM: EA = 20: 1, v / v). After the reaction was completed, the heating was stopped and the resulting system was allowed to cool naturally to room temperature. During the cooling process, layering phenomenon was found, with a tangerine fluorescence upper layer and a colorless lower layer. The liquid in the reaction tube was poured into a round-bottomed flask and subjected to rotary evaporation to remove the solvent, and the residue was subjected to extracting with DCM, washing with a saturated sodium chloride solution and purifying with a 100-200 mesh silica gel chromatographic column (with an eluent of DCM) to obtain a pure yellow product, i.e., the compound 3.

[0036] Step 3, synthesis of compound 4:

[0037] The compound 3 (151 mg), DMAP (47.14 mg) and DCC (100 mg) were accurately weighed on a balance, added into a 25 mL reaction tube, and then 5 mL of 29 11 24 tetrahydrofuran was added thereto to dissolve the above compounds; PCD A (106 mg) was accurately weighed and added into a small beaker, and 5 mL of tetrahydrofuran was then added thereto to dissolve PCDA, obtaining a PCDA solution. The PCDA solution was slowly added dropwise to the above reaction tube. During the reaction, the reaction tube was wrapped in tin foil to keep away from light, and put on a magnetic stirrer; the mixture therein was stirred at room temperature for 72 hours. The reaction was monitored by TLC. After the reaction was completed, the solution in the reaction tube was transferred to a round-bottomed flask, and tetrahydrofuran therein was removed by rotary evaporation under a reduced pressure (35 °C), and the resulting residue was dissolved with an appropriate amount of dichloromethane. The obtained solution was extracted with supersaturated NaHCOs solution to remove DCC; and an appropriate amount of sodium sulfate anhydrous was added to remove water to obtain a crude product. Finally, a small amount of silica gel was added to the crude product to make compounds be adsorbed on the silica gel, and the resulting mixture was subjected to rotary evaporation under a reduced pressure, obtaining powder. Then, the powder was slowly added to a packed silica gel column, and a layer of quartz glass was laid on the compound. The eluent was a mixture of dichloromethane and petroleum ether (dichloromethane : petroleum ether =1:1). The target compound 4 was obtained, which is confirmed by its 1H-NMR spectrum as shown in FIG. 1. FIG. 4 shows an SEM image of the compound 4 powder synthesized in step 3 of this example. FIG. 6 shows a high-resolution mass spectrum of the compound 4 synthesized in step 3 of Example 1, so as to verify the molecular structure of the synthesized compound 4.

[0038] Step 4, preparation of supramolecular polymerized fluorescent nanoparticles by a film hydration method:

[0039] First, stock solutions of NT-DA (i.e. the compound 4) and PCDA were prepared with chloroform as a solvent. The specific processes were as follows: 8.89 mg of NT-DA powder was accurately weighed and prepared into 1 mM stock solution of NT-DA in a 10 mL volumetric flask; 18.7 mg of PCDA powder was accurately weighed and prepared into 5 mM stock solution of PCDA in a 10 mL volumetric flask. The NT-DA sample was completely dissolved by sonicating for 10 minutes, and the PCDA sample was completely 29 11 24 dissolved by sonicating for 2 minutes. 10 pL of the stock solution of NT-DA and 10 pL of the stock solutions of PCDA were added to a round-bottom flask with a pipette, and the organic solvent was removed by rotary evaporation, thus forming a film on the roundbottom flask. 2 mL of deionized water at 80 °C was added into the round-bottomed flask, and sonicated for 5 minutes to obtain a precursor of supramolecular polymerized fluorescent nano-material. After cooling at room temperature, the precursor was placed in a refrigerator at 4 °C overnight for self-assembly to obtain nanoparticles. Before using, the nanoparticles were irradiated with a 254 nm UV lamp for 3 minutes to polymerize. FIG. 7 shows a particle size distribution diagram of supramolecular polymerized fluorescent nanoparticles formed in step 4 of this example, and it can be seen that the particle sizes are all concentrated around 132.9 nm. FIG. 8 shows an SEM image of supramolecular polymerized fluorescent nanoparticles formed in step 4 of this example, and a large number of fluorescent nanoparticles with similar particle sizes can be clearly seen.

[0040] Optical performance testing of NT-DA

[0041] Step: aUV absorption spectrum and a fluorescence emission spectrum of NT-DA were measured at 25 °C. The stock solution of the NT-DA probe was prepared with DMSO (1 x 10'3 mol / L) as a solvent. During the testing, 10 pL of the stock solution of the NT-DA probe was accurately taken with a pipette and added into a cuvette filled with 2 ml of different solvents, and the testing was conducted at room temperature. The changes of fluorescence emission spectrum of 10 pL NT-DA (1 mM) in DMSO / H2O mixed solvents (a total volume being 2 mL) with different volume ratios were investigated.

[0042] Results of optical performance testing

[0043] As shown in the UV-visible absorption spectrum of NT-DA in FIG. 2, there are two maximum absorption peaks. The emission spectrum in FIG. 3 is arranged at 500-800 nm, with the maximum absorption peak at about 590 nm. It can be seen that the compound has a large Stokes shift (167 nm), which avoids light pollution of excitation light and self-absorption of emission during biomedical imaging.

[0044] As shown in FIG. 5, NT-DA has a typical AIE effect, which is almost weakly emissive in DMSO. When 0%-90% deionized water is gradually added, with the increase 29 11 24 of water proportion, due to the limitation of intramolecular motion, the probes gradually form aggregation, effectively blocking the non-radiation channel and activating radiation transition. The fluorescence of AIEgen is activated, and the bright and continuously enhanced orange emission fluorescence appears at the emission wavelength of 588 nm, with the comparative emission intensity.

[0045] The above description of the embodiments is for the convenience of a person of ordinary skill in the technical field to understand and use the present disclosure. It is obvious that those skilled in the art could easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present disclosure is not limited to the above-mentioned embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present disclosure should be within the scope of the present disclosure.

Claims

1. An aggregation-inducedemission compound, having a molecular structuralformula ofwherein D moiety is triphenylamine or diphenylamine with an electron donor,having a structural formula ofwherein Ri is phenyl or hydrogen, R2 is hydrogen or boronic, and R3 is selected fromthe group consisting of hydrogen, hydroxyl, and amino.

2. The aggregation-induced emission compound of claim 1, wherein Ri, R2, and R3 each are hydrogen.

3. A method for preparing a supramolecular polymerized fluorescent nano-material, comprising the steps ofAl: covalently bonding compound 3 with 10,12-Pentacosadiynoic acid (PCDA) to obtain the aggregation-induced emission compound of claim 1 or 2;A2: dissolving the aggregation-induced emission compound obtained in step Al in dichloromethane or chloroform to obtain a solution I;29 11 24A3: dissolving PCDAin dichloromethane or chloroform to obtain a solution II;A4: preparing a precursor of the supramolecular polymerized fluorescent nanomaterial from the solution I obtained in step A2 and the solution II obtained in step A3 by a film hydration method; andA5: cooling the precursor obtained in step A4 and staying overnight in a refrigerator at a temperature of 2-6 °C to allow the precursor to self-assemble to obtain nanoparticles, and before using, irradiating the nanoparticles with a 254 nm ultra-violet (UV) lamp to allow the nanoparticles to polymerize to obtain the supramolecular polymerized fluorescent nano-material;wherein the compound 3 has a structural formula of.. OHO . N O.. ... N . .

4. The method for preparing the supramolecular polymerized fluorescent nanomaterial of claim 3, wherein the aggregation-induced emission compound is prepared by a process comprising the steps ofBl: dissolving the compound 3, 4-Dimethylaminopyridine (DMAP) and N, N'-dicyclohexylcarbodiimide (DCC) in an organic solvent, stirring for dissolution, slowly adding a PCDA solution thereto, and stirring for reaction in absence of light to obtain a mixed solution of reaction products; andB2: evaporating out the organic solvent from the mixed solution of reaction products, drying, dissolving a resulting residue in dichloromethane to obtain a solution III, extracting the solution III with a supersaturated NaHCOs solution to remove DCC, adding sodium sulfate anhydrous thereto to remove water to obtain a crude product, and29 11 24purifying the crude product to obtain the aggregation-induced emission compound.

5. The method for preparing the supramolecular polymerized fluorescent nanomaterial of claim 4, wherein a ratio of the compound 3, DMAP and DCC in step Bl is 151 mg: 47.14 mg: 100 mg.

6. The method for preparing the supramolecular polymerized fluorescent nanomaterial of claim 4, wherein the compound 3 is prepared by a process comprising the steps ofCl: adding compound 2, 4-(diphenylamino)phenylboronic acid and tetrakis(triphenylphosphine)palladium into a reactor, adding tetrahydrofuran (THF), redistilled dimethylformamide (DMF) and a K2CO3 solution thereto, and uniformly mixing to obtain a clear and transparent solution;C2: vacuumizing the clear and transparent solution obtained in step Cl, performing reaction under a protection of an inert gas at a temperature of 80 °C, monitoring the reaction by thin layer chromatography (TLC) during the reaction, stopping heating after the reaction is complete, naturally cooling a resulting reaction system to room temperature to obtain a layered liquid with a tangerine fluorescence upper layer and a colorless lower layer; andC3: removing solvent from the layered liquid obtained in step C2, extracting with dichloromethane (DCM), washing with a saturated sodium chloride solution, and purifying with a 100-200 mesh silica gel chromatographic column to obtain a pure yellow product, i.e., the compound 3;wherein the compound 2 has a structural formula of /  , OH0.. N.x OBr7. The method for preparing the supramolecular polymerized fluorescent nanomaterial of claim 6, wherein a ratio of the compound 2, 4-(diphenylamino)phenylboronic acid, and tetrakis(triphenylphosphine)palladium is 300 mg: 259 mg: 47 mg.

8. The method for preparing the supramolecular polymerized fluorescent nanomaterial of claim 6, wherein the compound 2 is prepared by a process comprising the steps ofDI: adding 4-bromo-l,8-naphthalic anhydride, 3-aminophenol, and acetic acid into a reactor, subjecting a resulting mixture to reaction under a protection of nitrogen at a temperature of 130 °C, monitoring the reaction by TLC during the reaction, adding water to dissolve the acetic acid after the reaction is complete, leaving a resulting system to stand, filtering to obtain a pale yellow solid, and recrystallizing with acetic acid to obtain a pure yellow solid powder, i.e., the compound 2.

9. The method for preparing the supramolecular polymerized fluorescent nanomaterial of claim 8, wherein a ratio of 4-bromo-l,8-naphthalic anhydride, 3-aminophenol, and acetic acid is 2.00 g: 1.023 g: 10 mL.

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