A single molecular weight fluorene-azobenzene amphiphilic oligomer precursor and oligomer and self-assembled fiber and preparation method

Abstract

The present invention discloses a single molecular weight fluorene-azobenzene amphiphilic oligomer and its self-assembled fiber and preparation method, which enriches and expands the research on main chain containing fluorene and azobenzene, and has guiding significance for the development of azobenzene and fluorene materials. The single molecular weight oligomer of the present invention has better product processing performance and physical properties; at the same time, the present invention adopts an iterative step-by-step growth strategy combined with an efficient monovalent copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction and accurately controls the position of azobenzene to accurately synthesize amphiphilic polymers of different sequences. The experimental operation is simple and easy, providing a theoretical basis for the precise exploration of the relationship between structure and performance; the present invention uses a solution self-assembly method to "top-down" accurately control the internal accumulation and external morphology of nanoparticles to construct 1D / 2D nanomaterials with special functions; in addition, the chemical reagents used in the method of the present invention are stable in the air, easy to operate, and highly efficient.

Description

Technical Field

[0001] The invention belongs to the field of monodisperse sequence polymer synthesis and solution self-assembly, and relates to a preparation method of an amphiphilic single molecular weight polymer containing fluorene and azobenzene in different sequence main chains and a solution self-assembly application. Background Art

[0002] Amphiphilic block copolymers can be self-assembled in selective solvents under the interaction of π-π stacking, hydrogen bonding and hydrophilicity by changing the composition, block concentration, solvent composition and properties, and temperature, and can be used to prepare nanoparticles with various morphologies and sizes. Amphiphilic polymer solution self-assembly not only improves the solution self-assembly theory system, but also provides value for the potential application of polymer nanoparticles in biomedicine (drug delivery, controlled release, etc.), catalysis and pollution control, cosmetics and other fields (Nisar, A.; Zhuang, J.; Wang, X., Chemistry of Materials 2009, 21 , 3745-3751.Zhang, A.; Bai, H.; Li, L., Chemical Reviews 2015, 115 ,9801-9868. Dong, R.; Liu, W.; Hao, J., Accounts of Chemical Research 2012, 45 ,504-513. Govindaraju, T.; Avinash, MB, Nanoscale 2012, 4 , 6102-6117.). Among them, amphiphilic π-conjugated polymers tend to be closely packed along the 1D / 2D direction during the assembly process due to their rigid planar structure, showing anisotropy. At the same time, due to strong interaction and electron mobility, they show unique optoelectronic properties. The solution self-assembly of conjugated polymers provides an effective way to precisely control the orderly stacking mode of molecules and the resulting optoelectronic properties.

[0003] Polyfluorene (PF) and its derivatives (PFs) are a class of conjugated polymers. They are the most promising high-efficiency blue luminescent materials due to their rigid structure, excellent thermal and chemical stability, easy side chain modification, and high fluorescence quantum efficiency (Cao, XY; Zhou, XH; Zi, H.; Pei, J., Macromolecules 2004, 37, 8874-8882. Li, J.; Bo, ZS, Macromolecules 2004, 37, 2013-2015.); azobenzene is a common stimuli-responsive group that responds to light, heat, and reduction. It can undergo reversible cis-trans isomerization under light irradiation or heating. When it is introduced into the main chain of the polymer, the photoinduced cis-trans isomerization will significantly affect the molecular configuration of the oligomer / polymer, forming a reversible curling / uncurling process. At present, most of the amphiphilic solution self-assembly studies are based on narrow distribution polymers obtained by active polymerization, which has certain limitations. Therefore, it is of great significance to construct amphiphilic oligomers with a single molecular weight and clear structure, and to synergistically drive self-assembly through multiple supramolecular effects, in order to precisely control the morphology and performance of polymer nanoparticles. The prior art has studied the solution self-assembly behavior of "sequence isomers" with the same composition, and found that with the increase of initial concentration, the "one head and one tail" sequence can only form spherical micelles. Therefore, it is necessary to develop single molecular weight amphiphilic polymers of different sequences and conduct research on their solution self-assembly to precisely control the morphology and performance expression of nanoparticles. Summary of the invention

[0004] In view of the above situation, the purpose of the present invention is to provide a method for preparing monodisperse amphiphilic polymers with different sequence main chains containing fluorene and azobenzene and their solution self-assembly applications, and to introduce responsive azobenzene units into conjugated polymer chains for solution self-assembly, so as to develop a variety of new functional 1D / 2D nanomaterials.

[0005] The present invention firstly utilizes a series of chemical reactions such as Sonogashira coupling, diazo coupling, nucleophilic substitution, esterification, nitration, reduction, etc. to synthesize fluorene and azobenzene monomers in multiple steps. First, the C7 position on the fluorene ring is nitrated, and an octyl group is introduced at the C9 position. Then, the Br at the C2 position is converted into an alkynyl protected by TBS by a Sonogashira coupling reaction, and the nitro group at the C7 position is reduced to an amino group by iron powder to obtain a fluorene monomer having an alkynyl protected by TBS at one end and an amino group at the other end. Azobenzene is first introduced with a TBS protective group, and then a reduction reaction is performed, followed by a diazo coupling reaction to synthesize an azobenzene intermediate, and then an azide site is introduced by nucleophilic substitution and a side chain is introduced by an esterification reaction to obtain an azobenzene monomer having an alkynyl protected by TBS at one end and a bromine at the other end. Then, TBS deprotection or amino or bromine azide reaction was selectively carried out, and then an iterative step-growth strategy and an efficient copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction were used to prepare single molecular weight fluorene-azobenzene precise sequence amphiphilic oligomer precursors with azobenzene located at different positions in the main chain, named 4F-4Azo, 2Azo-4F-2Azo and 4(F-Azo), respectively. Then, trifluoroacetic acid and dilute hydrochloric acid were used to convert the oligomer precursors into amphiphilic oligomers. Related tests have proved that this method can effectively synthesize single molecular weight amphiphilic polymers containing fluorene and azobenzene in the main chain, and the study found that the self-assembly behavior of the oligomer solution is sequence-dependent.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, the structure of which is shown below:

[0008]

[0009]

[0010]

[0011] The above-mentioned single molecular weight fluorene-azobenzene amphiphilic oligomer precursor is stripped of Boc protection to obtain an amino polymer, which is then quaternized to obtain a single molecular weight fluorene-azobenzene amphiphilic oligomer. Specifically, the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor is dissolved in trifluoroacetic acid, the trifluoroacetic acid is removed by rotary evaporation after the reaction, the concentrated solution is precipitated in a saturated NaHCO3 aqueous solution, centrifuged and dried to obtain a light yellow solid, which is then dissolved in tetrahydrofuran to obtain a clear and transparent solution, and then water is added dropwise, and then an HCl aqueous solution is added dropwise to achieve quaternization to obtain a single molecular weight fluorene-azobenzene amphiphilic oligomer.

[0012] The present invention discloses a method for preparing the above-mentioned single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, which is one of the following preparation methods:

[0013] Method 1: Using TBS-4F-N3 and alkyne-4Azo-Br-8Boc as raw materials, a copper-catalyzed azide-alkyne cycloaddition reaction was carried out to obtain a single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, 4F-4Azo;

[0014] Method 2: Using TBS-4F-N3 and alkyne-2Azo-Br-4Boc as raw materials, a copper-catalyzed azide-alkyne cycloaddition reaction is carried out to obtain alkyne-4F-2Azo-Br-4Boc; alkyne-4F-2Azo-Br-4Boc is then subjected to a copper-catalyzed azide-alkyne cycloaddition reaction with TBS-2Azo-N3-4Boc to obtain a single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, which is 2Azo-4F-2Azo;

[0015] Method 3: Using alkyne-F-NH2 and TBS-Azo-N3-2Boc as raw materials, a copper-catalyzed azide-alkyne cycloaddition reaction is carried out, and then TBS is deprotected or the amino group is converted into an azide using sodium azide to obtain TBS-2(F-Azo)-N3-4Boc or alkyne-2(F-Azo)-NH2-4Boc; then TBS-2(F-Azo)-N3-4Boc and alkyne-2(F-Azo)-NH2-4Boc are subjected to a copper-catalyzed azide-alkyne cycloaddition reaction to obtain a single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, which is 4(F-Azo).

[0016] In the present invention, the catalyst of the copper-catalyzed azide-alkyne cycloaddition reaction is cuprous bromide, and the ligand is pentamethyldiethylenetriamine; the reaction is carried out at room temperature for 40 to 50 hours.

[0017] The present invention discloses a solution self-assembly method of the above-mentioned single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, comprising the following steps: dissolving the above-mentioned single molecular weight fluorene-azobenzene amphiphilic oligomer precursor in a solvent after deprotection, then adding water and hydrochloric acid, and standing to achieve the solution self-assembly of the above-mentioned single molecular weight fluorene-azobenzene amphiphilic oligomer. Furthermore, the product of the solution self-assembly of the above-mentioned single molecular weight fluorene-azobenzene amphiphilic oligomer precursor is a nanofiber or a nanosphere.

[0018] The invention discloses a preparation method of a single molecular weight fluorene-azobenzene amphiphilic oligomer self-assembled fiber, comprising the following steps: deprotecting the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor 4F-4Azo and dissolving it in a solvent, then adding water and hydrochloric acid, and standing to obtain the single molecular weight fluorene-azobenzene amphiphilic oligomer self-assembled fiber with a nanofiber structure; further, removing the solvent from the solution after standing to obtain the single molecular weight fluorene-azobenzene amphiphilic oligomer nanofiber; this is the first disclosure of fluorene-azobenzene polymers assembled into nanofibers.

[0019] In the present invention, the solvent for dissolving the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor is tetrahydrofuran; the concentration of hydrochloric acid is 1 mol / L; the volume ratio of tetrahydrofuran, water and hydrochloric acid is 1:0.5:0.3-0.4; and the standing time is 5 minutes to 24 hours at room temperature, preferably 2 to 12 hours, and more preferably 8 to 12 hours.

[0020] The present invention discloses a single molecular weight amphiphilic polymer precursor and a polymer containing fluorene and azobenzene in the main chain, and studies the self-assembly behavior of the amphiphilic polymer solution, creatively discloses that the two-block oligomers assemble to form long nanofibers, and the thicker fibers are formed by the accumulation of fine entanglements; other polymers assemble to form a spherical structure. This proves that different polymers have different molecular accumulations during the assembly process, resulting in differences in the morphology of the assembly.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] 1. The present invention successfully introduces azobenzene stimuli-responsive groups into the polymer main chain to construct a new type of amphiphilic polymer containing different functional groups, enriching and expanding the research on main chain containing fluorene and azobenzene, and has guiding significance for the development of azobenzene and fluorene materials;

[0023] 2. The present invention combines the iterative step-growth strategy with the efficient copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to precisely control the position of azobenzene to precisely synthesize amphiphilic polymer precursors of different sequences, providing a method for efficiently modularizing the synthesis of single molecular weight and different sequence main chain amphiphilic polymers containing fluorene and azobenzene and broadens the application of this method in the preparation of nanomaterials by solution self-assembly;

[0024] 3. When the single molecular weight fluorene-azobenzene amphiphilic oligomer of the present invention is self-assembled, the internal accumulation and external morphology of the nanoparticles are precisely controlled "from top to bottom" in a solution self-assembly manner to construct 1D / 2D nanomaterials with special functions;

[0025] 4. The chemical reagents used in the method of the present invention are stable in the air, and the reaction operation in the method is simple, efficient, and convenient for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 H NMR spectra of (a) azobenzene monomer and (b) fluorene monomer.

[0027] Figure 2 The SEC elution curves of single molecular weight amphiphilic oligomer precursors with different main chains containing fluorene and azobenzene.

[0028] Figure 3 MALDI-TOF MS images of single molecular weight amphiphilic oligomer precursors containing fluorene and azobenzene in different main chains.

[0029] Figure 4 TEM image of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0030] Figure 5 TEM and AFM images of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0031] Figure 6 TEM image of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0032] Figure 7 TEM image of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0033] Figure 8 TEM image of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0034] Fig. 9 TEM image of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0035] Fig.10 TEM image of the aggregates formed after 4F-4Azo-8NH2 was assembled in THF / H2O / HCl.

[0036] Fig.11 This is the TEM image of the aggregates formed after 2Azo-4F-2Azo-8NH2 was assembled in THF / H2O / HCl.

[0037] Fig.12This is the TEM image of the aggregates formed after 4(F-Azo)-8NH2 was assembled in THF / H2O / HCl.

[0038] Fig.13 The UV-visible absorption spectra (ac) and fluorescence emission spectra (df) of the assembled solutions of different oligomers in THF / H2O / HCl before and after UV irradiation and after heating recovery. The black line is before UV irradiation, the red line is after UV irradiation, and the blue line is after heating recovery. Assembly conditions: Solvent ratio: V THF : V H20 : V THF (1M) = 1:0.5:0.4; initial concentration: C0=1.0 mg / mL; drop rate: 0.2 mL / h; temperature: 30 o C; stirring speed: 300 r / min.

[0039] Fig.14 SEM images of samples obtained by rapid evaporation of different oligomer assembly solutions on tin foil; (a) 4F-4Azo-8NH2, (b) 2Azo-4F-2Azo-8NH2, (c) 4(F-Azo)-8NH2. Assembly conditions: Solvent ratio: V THF : V H20 : V THF (1 M) = 1:0.5:0.4; initial concentration: C0=1.0 mg / mL; drop rate: 0.2 mL / h; temperature: 30 o C; stirring speed: 300 r / min. DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0041] Chemical reagents:

[0042] 2-Bromofluorene, Aladdin;

[0043] 1-Bromooctane, Energy-chemical;

[0044] tert-Butyldimethylsilylacetylene, Aladdin;

[0045] Bis(triphenylphosphine)palladium(II) dichloride, Aladdin;

[0046] Cuprous iodide, Aladdin;

[0047] 2-Hydroxy-5-nitrobenzyl alcohol, TCI;

[0048] tert-Butyldimethylsilyl-protected propyne bromide, Aladdin;

[0049] Salicyl alcohol, Merrill Chemical;

[0050] Boc- β -Alanine, Merrill Chemical;

[0051] Dicyclohexylcarbodiimide (DCC), Adamas;

[0052] 4-Dimethylaminopyridine (DMAP), Adamas;

[0053] Tetrabutylammonium fluoride (tetrahydrofuran solution), Anergy;

[0054] Pentamethyldiethylenetriamine (PMDETA), J&K;

[0055] Cuprous bromide (CuBr), Sinopharm;

[0056] Sodium azide, Aladdin;

[0057] 1, 2-Dibromoethane, Jiangsu Qiangsheng Functional Chemical Co., Ltd.;

[0058] Ammonium chloride, Jiangsu Qiangsheng Functional Chemical Co., Ltd.;

[0059] Sodium nitrite, Jiangsu Qiangsheng Functional Chemical Co., Ltd.;

[0060] Sodium bicarbonate, Jiangsu Qiangsheng Functional Chemical Co., Ltd.;

[0061] Hydrochloric acid, Jiangsu Qiangsheng Functional Chemical Co., Ltd.;

[0062] Dimethyl sulfoxide, tetrahydrofuran, chloroform, methanol, anhydrous ethanol, acetone, toluene, n-hexane, ethyl acetate, and anhydrous sodium sulfate were all analytical grade and were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0063] Test equipment and conditions:

[0064] H NMR spectroscopy ( 1 H NMR was performed using a Bruker 300 MHz NMR spectrometer with tetramethylsilane (TMS) as the internal standard and CDCl3 or DMSO- d 6 is a solvent.

[0065] Gel permeation chromatography (GPC) was tested on Agilent PL-50;

[0066] Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF) was performed using a Bruker Autoflex III (MALDI-TOF) mass spectrometer equipped with a 150 kHz II laser and a 355 nm nitrogen laser.

[0067] The ultraviolet-visible (UV-vis) absorption spectrum was measured using a Shimadzu UV-2600 spectrophotometer. The light source for the photoresponse test was a diode-pumped solid-state laser (DPSSL), model LSR532NL-500, with wavelengths of 365 nm and 435 nm, and an intensity of 0.5 mW / cm 2 .

[0068] The fluorescence emission spectra were measured using a HITACHI F-4600 fluorescence spectrophotometer.

[0069] Transmission electron microscopy (TEM) was performed using a HITACHI HT7700 instrument (Hitachi, Japan) with an accelerating voltage of 120 Kv.

[0070] Cold field emission scanning electron microscopy (SEM) was performed using HITACHI S-4700 (Hitachi, Japan) at a voltage of 15 KV.

[0071] AFM measurements were performed in tapping mode (VeecoInstruments Inc., Nanoscope IV).

[0072] The present invention uses an azobenzene monomer as shown in formula II and a fluorene monomer as shown in formula III, wherein TBS is tert-butyldimethylsilane;

[0073]

[0074] The synthetic route of the above-mentioned azobenzene monomer is as follows:

[0075]

[0076] a) Under stirring conditions, 2-羟基-5-硝基苄醇 : n TBS保护的溴丙炔 : n 碳酸钾 =1:1~1.2: 2~3, preferably n 2-羟基-5-硝基苄醇 : n TBS保护的溴丙炔 : n 碳酸钾 =1: 1.1: 1.5 molar ratio, 2-hydroxy-5-nitrobenzyl alcohol and TBS-protected propyne bromide were reacted under alkaline conditions for 12 hours to obtain intermediate (1);

[0077] b) n 中间体(1) : n 铁粉=1:3 molar ratio, first dissolve ammonium chloride, then reflux at 105°C for 1 hour to activate iron powder, add intermediate (1) and stir at 75°C for 12 hours to obtain intermediate (2);

[0078] c) Under stirring conditions, 中间体(2) : n 水杨醇 : n HCl : n NaNO2 : n NaOH : n NaHCO3 =1: 2~3: 3.6~4: 1.2~1.5: 3.5~4: 8~10, preferably n 中间体(2) : n 水杨醇 : n HCl : n NaNO2 : n NaOH : n NaHCO3 =1: 2: 3.8: 1.2: 3.8: 9 molar ratio, hydrochloric acid and sodium nitrite aqueous solution are sequentially added dropwise to the intermediate (2) to generate a diazonium salt solution, which is then added dropwise to a weak base solution containing salicyl alcohol and stirred at room temperature for 12 hours to obtain an intermediate (3);

[0079] d) Under stirring conditions, 中间体(3) : n 碳酸铯 : n 1, 2-二溴乙烷 =1: 5~6: 15~20, preferably n 中间体(3) :n 碳酸铯 : n 1, 2-二溴乙烷 =1: 5.8: 20 molar ratio, the intermediate (3) is mixed with anhydrous cesium carbonate and 1, 2-dibromoethane and stirred for 12 hours to obtain the intermediate (4);

[0080] e) Under stirring conditions, 中间体(4) : n Boc-β-丙氨酸 : n DMAP : n DCC =1: 2~3 : 1~1.2: 4~5, preferably n 中间体(4) : n Boc-β-丙氨酸 : n DMAP : n DCC =1: 2.2: 1: 4 molar ratio, the DCC solution was dissolved in dichloromethane and then added dropwise to the intermediate (3) and Boc- β -Alanine and DMAP mixed solvent, react in an ice-water bath for half an hour, then move to room temperature and continue stirring for 12 hours to obtain azobenzene monomer.

[0081] The synthetic route of the above fluorene monomer is as follows:

[0082]

[0083] a) 2-bromofluorene was reacted in a mixed solution of nitric acid and 1,2-dichloroethane for 1 hour, and then poured into ice methanol to obtain intermediate (1);

[0084] b) Under stirring conditions, 中间体(1) :n 1-溴辛烷 =1:1~3, preferably n 中间体(1) :n 1-溴辛烷 =1:2 molar ratio, KOH and DMSO were mixed, intermediate (1) and 1-bromooctane were added, and stirred at room temperature for 12 hours to obtain intermediate (2);

[0085] c) Under the protection of argon gas, PdCl2(pph3)2 :n CuI :n TBS保护的炔基 :n 中间体(2) =1:2~5:60~80:20~30, preferably n PdCl2(pph3)2 :n CuI :n TBS保护的炔基 :n 中间体(2) =1:2:60:25 molar ratio, the four substances were dissolved in 1:1 toluene and triethylamine, and stirred at 80°C for 12 hours to obtain intermediate (3);

[0086] d) n 中间体(3) :n 铁粉 =1:3 molar ratio, first dissolve ammonium chloride, then reflux at 105°C for 1 hour to activate iron powder, add intermediate (3) and stir at 75°C for 12 hours to obtain fluorene monomer;

[0087] In the present invention, a tetrabutylammonium fluoride (TBAF) tetrahydrofuran solution is used to remove the protective group TBS, thereby achieving the deprotection of the fluorene monomer and the azobenzene monomer; and sodium azide is used to convert the amino group or bromine group into an azide group, thereby achieving the azide reaction of the fluorene monomer and the azobenzene monomer; the schematic diagram is as follows:

[0088]

[0089] a) Fluorene monomer / azobenzene deprotection: 芴单体 / 偶氮苯单体 : n 脱保护试剂 =1:3~6, preferably n 芴单体 / 偶氮苯单体 :n 脱保护试剂 =1:5 molar ratio, and removing the TBS protecting group to obtain an alkynylfluorene monomer / azobenzene monomer, wherein the deprotecting agent is tetrabutylammonium fluoride, the solvent is anhydrous tetrahydrofuran, and the reaction conditions are stirring at room temperature for 30 minutes.

[0090] b) Fluorene monomer azidation reaction: Stir in an ice-water bath with n 芴单体 : n 盐酸: n 亚硝酸钠 =1:3.6~3.8:1.2~1.5, preferably n 芴单体 : n 盐酸 : n 亚硝酸钠 =1:3.6:1.2 molar ratio, slowly add hydrochloric acid and sodium nitrite aqueous solution to the fluorene monomer, keep the reaction temperature at 0-5°C, continue to react for 1 hour after the addition is completed, and obtain a diazonium salt solution; then 芴单体 :n 叠氮化钠 =1:2 molar ratio, sodium azide (2 eq) was added to the diazonium salt solution, and the mixture was stirred at 0-5°C to obtain an azidofluorene monomer;

[0091] Azobenzene azidation reaction: Under stirring conditions, 偶氮苯单体 :n 叠氮化钠 =1:3~5, preferably n 偶氮苯单体 :n 叠氮化钠 =1:3 molar ratio, azobenzene monomer and sodium azide were treated in DMF solvent at 80°C with stirring for 12 hours to obtain azidoazobenzene monomer.

[0092] The above-mentioned deprotected and azidized monomers are used as raw materials to synthesize different sequence single molecular weight fluorene-azobenzene amphiphilic oligomer precursors. Specifically, different sequence single molecular weight fluorene-azobenzene amphiphilic oligomer precursors are obtained by step-growth and efficient monovalent copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, wherein n 叠氮化合物 :n 含炔基化合物 =1:1.2~1.5, preferably n 叠氮化合物 :n 含炔基化合物 =1:1.2 molar ratio to carry out CuAAC reaction, synthesize single molecular weight different sequence amphiphilic fluorene-azobenzene oligomer precursor. The catalyst is catalytic amount of cuprous bromide, the ligand is pentamethyldiethylenetriamine, the solvent is tetrahydrofuran, deoxygenated and sealed tube reaction for 48 hours. Then, the side chain of single molecular weight precise sequence amphiphilic fluorene-azobenzene oligomer precursor with azobenzene at different positions in the main chain is deprotected to synthesize different sequence amphiphilic oligomers. 齐聚物前体 :n 三氟乙酸 =1: 10~30, preferably n 齐聚物前体 :n 三氟乙酸=1: 10 molar ratio, the oligomer precursor is dissolved in trifluoroacetic acid, most of the trifluoroacetic acid is removed by rotary evaporation after reacting for 12 h at room temperature, and then saturated NaHCO3 aqueous solution is used to adjust pH to neutrality, and centrifugal drying obtains an oligomer whose azobenzene side chain is an amino group. Then dilute hydrochloric acid is added to the oligomer tetrahydrofuran solution whose side chain is an amino group, and both the amino group can be converted into a quaternary ammonium salt and become an amphiphilic oligomer, and solution self-assembly can be performed. Specifically, deionized water is dripped into the tetrahydrofuran solution of the oligomer, and then quantitative 1.0mol / L of dilute HCl is dripped into the mixed solvent to convert the amino group into a hydrophilic quaternary ammonium salt, driving the solution self-assembly. The specific experimental operation is as follows: 1.0 mL of a tetrahydrofuran solution of an oligomer having a concentration of 1.0 mg / mL is taken in an ampoule bottle, and the mixture is stirred at 30 ℃ for 2 hours. o C, first add 0.5 mL of Milli-Q water to the solution, then continue to add 0.4 mL of 1.0 mol / L dilute HCl, slowly stir at 300 r / min, and after the assembly is completed, seal the ampoule and store it at room temperature to obtain the assembled product.

[0093] Example 1: Synthesis of azobenzene donor

[0094] 1. Synthesis of azobenzene intermediate (1):

[0095] Weigh 2-hydroxy-5-nitrobenzyl alcohol (1.0 g, 5.91 mmol) and potassium carbonate (1.23 g, 8.87 mmol) in a 100 mL single-necked round-bottom flask, add TBS-protected propargyl bromide (1.51 g, 6.51 mmol) and 35 mL acetone, and heat to 70 °C. o The reaction mixture was heated to reflux at 370 °C and filtered after completion of the reaction by TLC. The mixture was rinsed with a large amount of acetone. The filtrate was concentrated and dried in vacuo to obtain 1.53 g of the target product as a light yellow solid.

[0096]

[0097] 2. Synthesis of azobenzene intermediate (2):

[0098] In a 50 mL single-necked round-bottom flask, ammonium chloride (2.16 g, 40.48 mmol) was dissolved in a small amount of water, and iron powder (0.70 g, 12.46 mmol) was added. o C for 1 h and then cooled to 75 oC. Then, the intermediate (1) (1.0 g, 3.12 mmol) dissolved in 14 mL of ethanol was slowly added to the reaction system and monitored by TLC until the reaction was completed. A layer of diatomaceous earth was placed on the Buchner funnel, and the reaction solution was filtered to remove iron powder. After rotary evaporation of the filtrate, it was extracted with ethyl acetate and saturated brine. The organic phase was collected and purified by column chromatography (petroleum ether: ethyl acetate = 2:1). After rotary drying, 683.25 mg of the light brown target product was obtained.

[0099]

[0100] 3. Synthesis of azobenzene intermediate (3):

[0101] Diazotization reaction: weigh the intermediate (2) (200.0 mg, 0.69 mmol) and dissolve it in 1.0 mL methanol. Add HCl (230 μL, 2.61 mmol) dilute solution dropwise in an ice-water bath, then continue to add NaNO2 (53.54 mg, 0.78 mmol) aqueous solution dropwise. Continue stirring for 1 h and then add urea to react with excess NaNO2 to obtain a diazonium salt solution.

[0102] Coupling reaction: Weigh salicyl alcohol (161.86 mg, 1.31 mmol) and NaOH (107.17 mg, 2.68 mmol) in 30 mL of water. After complete dissolution, add NaHCO3 (537.84 mg, 6.40 mmol) to adjust the pH to about 9. In an ice-water bath, add the above diazonium salt solution dropwise to the solution to react for 2 h, then continue to react at room temperature for 12 h. After TLC tracking and monitoring until the end of the reaction, filter and purify by column chromatography (petroleum ether: ethyl acetate = 1:1). After spin drying, 170.00 mg of the yellow target product was obtained.

[0103]

[0104] 4. Synthesis of azobenzene intermediate (4):

[0105] Weigh anhydrous cesium carbonate (1.71 g, 25 mmol) into a 50 mL single-necked round-bottom flask, add 1,2-dibromoethane (16 mL, 86.02 mmol) and 17 mL acetonitrile, mix thoroughly, and heat to 65 o C, weigh the intermediate (3) (1.71 g, 4.34 mmol) and add it to a round-bottom flask, and monitor the reaction by TLC until the reaction is complete. Remove cesium carbonate by filtration, and purify by column chromatography (petroleum ether: ethyl acetate = 1:1). After spin drying, 2.18 g of the orange-yellow target product is obtained.

[0106]

[0107] 5. Synthesis of azobenzene donor:

[0108] Weigh the intermediate (4) (150.00 mg, 0.28 mmol), Boc- β -Alanine (117.32 mg, 0.62mmol), DMAP (34.45 mg, 0.28 mmol) were dissolved in 6 mL of dichloromethane. EDCI (230.72 mg, 1.12mmol) was dissolved in 2 mL of dichloromethane and added dropwise to the above system under ice-water bath conditions. After reacting for 0.5 h, the reaction was continued at room temperature. After TLC tracking and monitoring, the reaction was extracted with dichloromethane and saturated brine, and the organic phase was collected, dried by rotary evaporation, and purified by column chromatography (petroleum ether: ethyl acetate = 1:1). After rotary drying, 225.00 mg of the orange-yellow target product was obtained, which was TBS-Azo-Br-2Boc.

[0109]

[0110] The obtained azobenzene monomer was characterized by hydrogen nuclear magnetic resonance spectroscopy, and its spectrum is as follows Figure 1 As shown in a, it shows that the monomer purity is high.

[0111] TBS-Azo-Br-2Boc (66.92 mg, 1.03 mmol) and sodium azide (133.9 mg, 2.06 mmol) were dissolved in 5 mL DMF and heated at 80 °C. o The reaction was stirred at 40 °C for 12 h and followed by TLC until the reaction was completed. After cooling to room temperature, the mixture was extracted with ethyl acetate and washed three times with saturated brine. The organic phase was collected and dried, concentrated by rotary evaporation, and dried to obtain an orange-yellow viscous substance (63.46 mg) TBS-Azo-N3-2Boc with a yield of about 99.0%.

[0112] TBS-Azo-Br-2Boc (200 mg, 0.23 mmol) was dissolved in 10 mL of anhydrous THF, and TBAF solution (300 μL, 1.14 mmol) was added thereto. The mixture was stirred at room temperature for 0.5 h and monitored by TLC until the reaction was completed. THF was removed by rotary evaporation, and the mixture was extracted with ethyl acetate and washed three times with saturated brine. The organic phase was collected and dried, concentrated by rotary evaporation, and dried to obtain a brown solid (171.29 mg) alkyne-Azo-Br-2Boc with a yield of about 98.5%.

[0113]

[0114] To a 10 mL Schlenk tube, add TBS-Azo-N3-2Boc (85.69 mg, 0.11 mmol) and alkyne-Azo-Br-2Boc (117.00 mg, 0.15 mmol) dissolved in 5 mL of anhydrous and oxygen-free THF, then add PMDETA (26.69 mg, 0.15 mmol) and CuBr (14.63 mg, 0.11 mmol), and purify the tube by argon gas pumping three times. After reacting at room temperature for 48 hours, remove tetrahydrofuran by rotary evaporation, extract with ethyl acetate, wash three times with saturated brine, collect the organic phase, dry it, and purify it by column chromatography (silica gel, eluent: V PE / V EA = 1 / 4). The product was concentrated by rotary evaporation and then dried in vacuum to obtain an orange-red viscous substance (150.56 mg) TBS-2Azo-Br-4Boc (TBS-2Azo-Br), with a yield of about 92.1%. 1 H NMR (300 MHz,CDCl3) δ 7.94 (s, 1H), 7.81 (tt, J = 7.1, 2.5 Hz, 8H), 7.09 (dd, J = 13.3, 8.6Hz, 2H), 6.86 (d, J = 8.8 Hz, 2H), 5.30 (s, 2H), 5.23-5.11 (m, 6H), 5.07 (s,4H), 4.75 (d, J = 13.1 Hz, 4H), 4.43 (t, J = 4.9 Hz, 2H), 4.31 (t, J = 6.0Hz, 2H), 3.67-3.55 (m, 5H), 3.37-3.25 (m, 8H), 2.51 (qd, J = 6.4, 1.8 Hz,8H), 1.31 (d, J = 7.0 Hz, 38H), 0.79 (s, 9H).

[0115] TBS-2Azo-Br-4Boc (1.01 mmol) and sodium azide (2.02 mmol) were dissolved in 5 mL DMF and heated at 80 oThe reaction was stirred at 40 °C for 12 h and the reaction was monitored by TLC until the reaction was completed. After cooling to room temperature, the mixture was extracted with ethyl acetate and washed three times with saturated brine. The organic phase was collected and dried, concentrated by rotary evaporation, and dried to obtain TBS-2Azo-N3-4Boc.

[0116] TBS-2Azo-Br-4Boc (0.22 mmol) was dissolved in 10 mL of anhydrous THF, and TBAF solution (2.26 mmol) was added thereto. The mixture was stirred at room temperature for 0.5 h and monitored by TLC until the reaction was completed. THF was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed three times with saturated brine, and the organic phase was collected and dried. The organic phase was concentrated by rotary evaporation and then dried to obtain alkyne-2Azo-Br-4Boc.

[0117] TBS-2Azo-N3-4Boc and alkyne-2Azo-Br-4Boc were subjected to a "CuAAC" click reaction using the same parameters as TBS-2Azo-Br-4Boc to obtain TBS-4Azo-Br-8Boc (TBS-4Azo-Br). 1 H NMR (300 MHz,CDCl3) δ 8.01 (s, 3H), 7.95-7.68 (m, 16H), 7.24-7.04 (m, 5H), 6.96 (t, J =7.1 Hz, 4H), 5.52-5.04 (m, 28H), 4.96-4.80 (m, 9H), 4.61-4.23 (m, 8H), 4.21-3.57 (m, 5H), 3.41 (s, 16H), 2.61 (q, J = 7.0, 5.6 Hz, 16H), 1.41 (d, J = 6.9Hz, 73H), 0.89 (s, 9H), 0.09 (d, J = 7.5 Hz, 5H).

[0118] TBS-4Azo-Br-8Boc (0.22 mmol) was dissolved in 10 mL of anhydrous THF, and TBAF solution (2.27 mmol) was added thereto. The mixture was stirred at room temperature for 0.5 h and monitored by TLC until the reaction was completed. THF was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed three times with saturated brine, and the organic phase was collected and dried. The organic phase was concentrated by rotary evaporation and then dried to obtain alkyne-4Azo-Br-8Boc.

[0119] Example 2: Synthesis of fluorene donor.

[0120] 1. Synthesis of fluorene intermediate (1):

[0121] Nitric acid (10 mL) and 1,2-dichloroethane (80 mL) were stirred evenly for 10 min, 2-bromofluorene (10.00 g, 41.15 mmol) was added and stirring was continued for 1 h. After the reaction was completed as monitored by TLC, ice methanol was precipitated, the precipitate was collected by filtration and dried to obtain 10.61 g of the target product.

[0122]

[0123] 2. Synthesis of fluorene intermediate (2):

[0124] Finely grind KOH (10.00 g, 178.50 mmol) and DMSO (50 mL) and mix evenly for 10 min. Then add intermediate (1) (5.00 g, 17.30 mmol) and continue stirring for 20 min. Then add 1-bromooctane (6.64 mL, 37.80 mmol) and stir for 12 h. After the reaction is completed by TLC monitoring, extract with dichloromethane, dry, concentrate by rotary evaporation, and purify by column chromatography (petroleum ether: ethyl acetate = 64:1). After rotary drying, 8.16 g of the target product is obtained.

[0125]

[0126] 3. Synthesis of fluorene intermediate (3):

[0127] Under argon atmosphere, intermediate (2) (256.50 mg, 0.50 mmol) was dissolved in 10 mL of a mixed solvent of triethylamine and anhydrous toluene (1:1). Then, PdCl2(pph3)2 (14.10 mg, 0.02 mmol), CuI (7.60 mg, 0.04 mmol), TBS-protected alkynyl (168.00 mg, 1.20 mmol), 80 o The mixture was stirred at 37 °C for 12 h. After the reaction was completed by TLC monitoring, the mixture was extracted with dichloromethane, dried, concentrated by rotary evaporation, and purified by column chromatography (petroleum ether: ethyl acetate = 32:1) to obtain 202.00 mg of the target product after rotary drying.

[0128]

[0129] 4. Synthesis of fluorene donor:

[0130] Ammonium chloride (280.08 mg, 5.24 mmol) was dissolved in water, and iron powder (68.41 mg, 1.22 mmol) was added at 105 o C for 1 h, then cooled to 75o C. Then, the intermediate (3) (200.00 mg, 0.35 mmol) dissolved in anhydrous ethanol was added and reacted for 12 h. After the reaction was completed by TLC monitoring, a layer of diatomaceous earth was spread for suction filtration, and the filtrate was extracted with dichloromethane by rotary evaporation, dried, concentrated by rotary evaporation, and purified by column chromatography (petroleum ether: ethyl acetate = 32:1). After rotary drying, 80.00 mg of the target product was obtained.

[0131]

[0132] The obtained fluorene monomer was characterized by hydrogen nuclear magnetic resonance spectrum, and its spectrum is as follows Figure 1 As shown in b, it shows that the monomer purity is high.

[0133] TBS-4F-NH2 is as follows:

[0134]

[0135] Diazo reaction: Dissolve the fluorene donor TBS-4F-NH2 (0.40 mmol) in 5 mL of ethyl acetate, then drop into aqueous hydrochloric acid solution (3.6 eq) and aqueous NaNO2 solution (1.2 eq), stir in an ice-water bath for 1 h, then add urea and NaNO2 to react to obtain a diazo solution; add aqueous NaN3 (51.74 mg, 0.80 mmol) dropwise to the above diazo solution; stir in an ice-water bath for 1 h, after the reaction is completed, pour the reaction solution into water, extract with ethyl acetate, dry, concentrate by rotary evaporation, purify by column chromatography (petroleum ether: dichloromethane = 8:1), and spin dry to obtain TBS-4F-N3.

[0136] Example 3: Synthesis of 4F-4Azo

[0137] First, the fourth generation of fluorene was azidated with sodium azide, and the fourth generation of azobenzene was removed by TBS using tetrabutylammonium fluoride in tetrahydrofuran. TBS-4F-N3 (322.00 mg, 0.17 mmol) and alkyne-4Azo-Br-8Boc (162.50 mg, 0.06 mmol) dissolved in 30 mL of anhydrous and oxygen-free THF were added to a 10 mL Schlenk tube, and then PMDETA (28.65 mg, 0.17 mmol) and CuBr (15.78 mg, 0.11 mmol) were added. The tube was sealed by argon gas pumping three times to deoxygenate. After reacting at room temperature for 48 h, tetrahydrofuran was removed by rotary evaporation, and extracted with ethyl acetate and saturated brine. The organic phase was collected and dried, and purified by column chromatography (silica gel, eluent: V PE / V THF= 1 / 2). The product was concentrated by rotary evaporation and dried to obtain an orange-red solid (213.56 mg) with a yield of about 79.8%. 1 H NMR (300 MHz, CDCl3) δ 8.52-8.19 (m, 5H),8.16-7.61 (m, 43H), 7.57-7.39 (m, 2H), 7.25-7.03 (m, 4H), 6.97 (d, J = 7.2Hz, 6H), 5.53-4.97 (m, 32H), 4.95-4.74 (m, 7H), 4.61-4.34 (m, 8H), 3.40 (q, J = 5.9 Hz, 16H), 2.61 (qt, J = 6.3, 3.0 Hz, 16H), 1.81 (s, 14H), 1.42 (d, J =9.5 Hz, 86H), 1.32-0.93 (m, 102H), 0.92-0.51 (m, 44H), 0.24 (s, 5H), 0.07 (s, 4H).

[0138]

[0139] Example 4 Synthesis of 2Azo-4F-2Azo

[0140] TBS-4F-N3 (500.00 mg, 0.26 mmol) and alkyne-2Azo-Br-4Boc (459.92 mg, 0.31 mmol) dissolved in 30 mL of anhydrous and oxygen-free THF were added to a 20 mL Schlenk tube, and PMDETA (107.45 mg, 0.62 mmol) and CuBr (74.11 mg, 0.52 mmol) were added thereto respectively. The tube was sealed by argon evacuation three times for deoxygenation. After reacting at room temperature for 48 h, extraction was performed, column chromatography was purified and dried to obtain TBS-4F-2Azo-Br-4Boc. Then, TBS-4F-2Azo-Br-4Boc was deprotected by TBS using TBAF to obtain alkyne-4F-2Azo-Br-4Boc, which was the same as above.

[0141] Add alkyne-4F-2Azo-Br-4Boc (530.00 mg, 0.16 mmol) and TBS-2Azo-N3-4Boc (1070.00 mg, 0.69 mmol) dissolved in 10 mL of anhydrous and oxygen-free THF to a 20 mL Schlenk tube, then add PMDETA (168.00 mg, 0.97 mmol) and CuBr (57.4 mg, 0.40 mmol), and purify the tube by argon gas pumping three times. After reacting at room temperature for 48 h, remove tetrahydrofuran by rotary evaporation, extract with ethyl acetate, wash three times with saturated brine, collect the organic phase, dry it, and purify it by column chromatography (silica gel, eluent: V PE / V THF = 1 / 1). The product was concentrated by rotary evaporation and dried to obtain an orange-red solid (533.30 mg) with a yield of about 68.5%. 1 H NMR (300 MHz, CDCl3) δ 8.42-8.15 (m, 6H),8.11-7.63 (m, 43H), 7.24-7.04 (m, 5H), 6.98 (t, J = 8.4 Hz, 4H), 5.53-5.20(m, 18H), 5.17 (d, J = 4.8 Hz, 12H), 4.99-4.73 (m, 11H), 4.55 (d, J = 10.7Hz, 8H), 3.43 (dd, J = 11.2, 5.9 Hz, 16H), 2.62 (qd, J = 6.7, 5.9, 2.8 Hz,16H), 1.73 (s, 15H), 1.51-1.33 (m, 72H), 1.17 (d, J = 53.2 Hz, 88H), 0.89 (s,10H), 0.87-0.52 (m, 39H), 0.08 (d, J = 8.0 Hz, 7H).

[0142]

[0143] Example 5 Synthesis of 4(F-Azo) Oligomers

[0144] Alkyne-F-NH2 is as follows:

[0145]

[0146] TBS-Azo-N3-2Boc (969.00 mg, 1.14 mmol) and alkyne-F-NH2 (590.00 mg, 1.37 mmol) dissolved in 15 mL of anhydrous and oxygen-free THF were added to a 25 mL Schlenk tube, and then PMDETA (297.38 mg, 1.72 mmol) and CuBr (164.11 mg, 1.14 mmol) were added. The tube was sealed by argon gas three times for deoxygenation. After reacting at room temperature for 48 h, it was extracted and purified by column chromatography and dried to obtain TBS-(Azo-F)-Br-2Boc. With this macromolecule as a repeating unit, TBAF was used for TBS deprotection or sodium azide was used to convert the amino group into azide, and 2(F-Azo) was synthesized by step-growth, and 4(F-Azo) was prepared from 2(F-Azo).

[0147] TBS-(Azo-F)-Br-2Boc (0.22 mmol) was dissolved in 10 mL of anhydrous THF, and TBAF solution (0.44 mmol) was added thereto. The mixture was stirred at room temperature for 0.5 h and monitored by TLC until the reaction was completed. THF was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed three times with saturated brine, and the organic phase was collected and dried. The mixture was concentrated by rotary evaporation and then dried to obtain alkyne-(Azo-F)-Br-2Boc.

[0148] TBS-(Azo-F)-Br-2Boc (1.01 mmol) and sodium azide (2.02 mmol) were dissolved in 5 mL DMF and heated at 80 °C. o The reaction was stirred at 40 °C for 12 h and the reaction was monitored by TLC until the reaction was completed. After cooling to room temperature, the mixture was extracted with ethyl acetate and washed three times with saturated brine. The organic phase was collected and dried, concentrated by rotary evaporation, and dried to obtain TBS-(Azo-F)- N3-2Boc.

[0149] TBS-(Azo-F)- N3-2Boc (1.14 mmol) and alkyne-(Azo-F)-Br-2Boc (1.37 mmol) dissolved in 15 mL of anhydrous and oxygen-free THF were added to a 25 mL Schlenk tube, and then PMDETA (1.72 mmol) and CuBr (1.14 mmol) were added. The tube was sealed by pumping argon three times for deoxygenation. After reacting at room temperature for 48 h, extraction was performed, and column chromatography was used to purify and dry to obtain TBS-2(Azo-F)-Br-2Boc.

[0150] TBS-2(Azo-F)-Br-2Boc (0.22 mmol) was dissolved in 10 mL of anhydrous THF, and TBAF solution (0.44 mmol) was added thereto. The mixture was stirred at room temperature for 0.5 h and monitored by TLC until the reaction was completed. THF was removed by rotary evaporation, and the mixture was extracted with ethyl acetate. The mixture was washed three times with saturated brine, and the organic phase was collected and dried. The mixture was concentrated by rotary evaporation and then dried to obtain alkyne-2(Azo-F)-Br-2Boc.

[0151] TBS-2(Azo-F)-Br-2Boc (1.01 mmol) and sodium azide (2.02 mmol) were dissolved in 5 mL DMF and heated at 80 °C. o The reaction was stirred at 40 °C for 12 h and the reaction was monitored by TLC until the reaction was completed. After cooling to room temperature, the mixture was extracted with ethyl acetate and washed three times with saturated brine. The organic phase was collected and dried, concentrated by rotary evaporation, and dried to obtain TBS-2(Azo-F)- N3-2Boc.

[0152] TBS-2(F-Azo)-N3-4Boc (304.10 mg, 0.12 mmol) and alkyne-2(F-Azo)-NH2-4Boc (383.10 mg, 0.16 mmol) dissolved in 30 mL of anhydrous and oxygen-free THF were added to a 50 mL Schlenk tube, and then PMDETA (41.60 mg, 0.24 mmol) and CuBr (17.20 mg, 0.12 mmol) were added. The tube was sealed by argon gas pumping three times for deoxygenation. After reacting at room temperature for 48 h, tetrahydrofuran was removed by rotary evaporation, extracted with ethyl acetate, washed three times with saturated brine, and the organic phase was collected and dried, and purified by column chromatography (silica gel, eluent: V PE / V THF = 1 / 1). The product was concentrated by rotary evaporation and dried to obtain an orange-red solid (358.50 mg) with a yield of about 61.4%, abbreviated as 4(F-Azo). 1 H NMR (300 MHz, CDCl3) δ 8.22 (d, J = 10.7 Hz, 8H), 7.87 (dt, J = 40.2, 31.5 Hz, 39H), 7.00 (d, J =9.7 Hz, 9H), 5.56-5.17 (m, 25H), 5.01 (s, 9H), 4.87 (d, J= 24.9 Hz, 12H), 4.55 (s, 8H), 3.43 (s, 16H), 2.62 (s, 16H), 2.04 (dd, J = 17.4, 10.0 Hz,20H), 1.54-1.36 (m, 105H), 1.34-0.94 (m, 154H), 0.96-0.51 (m, 76H), 0.08 (d, J = 6.7 Hz, 12H).

[0153]

[0154] The single molecular weight polymer precursors with different main chains containing fluorene and azobenzene obtained above were characterized by SEC elution curves and MALDI-TOF MS graphs, such as Figure 2 , Figure 3 shown.

[0155] Example 6 Deprotection of Boc

[0156] 4F-4Azo (260.00 mg) was dissolved in 1 mL of trifluoroacetic acid. After reacting at room temperature for 12 h, the trifluoroacetic acid was removed by rotary evaporation. The concentrated solution was precipitated in a saturated aqueous solution of NaHCO3 and centrifuged to obtain a light yellow solid 4F-4Azo-8NH2. The method for removing Boc from the side chain of 2Azo-4F-2Azo-8NH2 and 4(F-Azo)-8NH2 was the same as that of 4F-4Azo-8NH2.

[0157] Embodiment 7

[0158] Take 1.0 mL of 1.0 mg / mL 4F-4Azo-8NH2 THF solution in a 5.0 mL ampoule. At 30°C, first add 0.5 mL of Milli-Q water (drop rate: 0.2 mL / h) to the solution, then continue to drop 0.4 mL of 1.0 mol / L HCl aqueous solution (drop rate: 0.2 mL / h), stir at 300 r / min, and after the addition is completed, seal the ampoule and let it stand at room temperature for 12 hours. Figure 4 This is a TEM photo after standing, where many nanofibers can be clearly observed. The height of these tiny fibers was characterized by AFM, which was about 9.8 nm. Figure 5 Theoretical simulations show that the length of the main chain of 4F-4Azo-8NH2 in the most stable state is 11.7 nm. The actual measured value is close to the theoretical calculated value, indicating that the assembly of 4F-4Azo-8NH2 solution is a monolayer support.

[0159] Embodiment 8

[0160] The amount of HCl aqueous solution in Example 7 was adjusted to 0.3 mL, and the rest remained unchanged. Figure 6 .

[0161] The amount of Milli-Q water in Example 7 was adjusted to 1 mL, and the rest remained unchanged. Figure 7 .

[0162] The concentration of the HCl aqueous solution in Example 7 was adjusted to 2 mol / L, and the rest remained unchanged. Figure 8 .

[0163] The room temperature in Example 7 was adjusted to 2 hours, and the rest remained unchanged. Fig. 9 .

[0164] The room temperature in Example 7 was adjusted to 24 hours, and the rest remained unchanged. Fig.10 .

[0165] Embodiment 9

[0166] The 4F-4Azo-8NH2 in Example 7 was replaced by 2Azo-4F-2Azo-8NH2, and the rest remained unchanged. The assembly is shown in FIG. Fig.11 .

[0167] The 4F-4Azo-8NH2 in Example 7 was replaced by 4(F-Azo)-8NH2, and the rest remained unchanged. The assembly is shown in FIG. Fig.12 .

[0168] Embodiment 10

[0169] The assembled solution was illuminated with 365 nm ultraviolet light (intensity of 0.5 mW / cm 2 ) for irradiation. The whole process was carried out in a dark environment. Except for ultraviolet light, there was no light of other wavelengths. After irradiation for a certain period of time, the TEM sample was prepared in a dark environment. After the sample was prepared, it was wrapped with tin foil and stored away from light. Using 365 nm ultraviolet light irradiation or heating, the changes in ultraviolet absorption and fluorescence emission of different sequence oligomer assembly solutions during the photoisomerization of azobenzene and the light responsiveness of the oligomer assembly were studied by ultraviolet absorption spectroscopy and fluorescence emission spectroscopy, such as Fig.13As shown. It can be clearly observed that after UV irradiation, the trans absorption peak intensity at 350 nm decreased significantly, and the fluorescence emission intensity increased significantly. This is because during the UV irradiation process, azobenzene changes from trans to cis configuration, and the non-planar cis configuration destroys the π-π plane stacking of azobenzene, causing the aggregates to dissociate and the fluorescence intensity to increase. After heating recovery, azobenzene changes from cis configuration to a more planar trans configuration, and the trans absorption peak intensity at 350 nm increases, while the fluorescence emission intensity decreases. At the same time, the effect of azobenzene photoisomerization on the morphology of the oligomer assembly can be observed. Under UV irradiation, the non-planar cis configuration of azobenzene hinders stacking, and the initial state of the fiber and spherical assembly dissociates.

[0170] Embodiment 11

[0171] The assembled assembly solution was dropped onto a clean tin foil, and the solvent was quickly dried in a vacuum oven at 30°C to obtain a sample for SEM testing. The test results are as follows: Fig.14 As shown in (ac), similar to the results measured by TEM, 4F-4Azo-8NH2 is a curled and entangled long fiber, and 2Azo-4F-2Azo-8NH2 and 4(F-Azo)-8NH2 are stacked spherical particles.

[0172] The above results fully demonstrate that slight adjustments at the polymer molecular level, such as sequence, will significantly affect the internal aggregation state of the aggregate and the final assembly morphology. The original driving force of individuals in nature comes from assembly, and amphiphilic polymer solution self-assembly is a particularly important type of assembly. Various influencing factors assemble under the interaction force to form various morphological assemblies, which have potential applications in the fields of biomedicine, chemistry, and environment. However, so far, there are few studies on the relationship between sequence and solution self-assembly behavior, and there are currently few reports on polymers containing both azobenzene and fluorene in the main chain and their properties. There are only studies on supramolecular chirality, photo-oriented orientation, reduction-induced fluorescence, screening of single-walled carbon nanotubes and nanowires, etc. The present invention successfully introduces azobenzene stimulus responsive groups into the polymer main chain to construct a new type of amphiphilic polymer containing different functional groups, enriching and expanding the research on main chain containing fluorene and azobenzene, and has guiding significance for the development of azobenzene and fluorene materials. At the same time, for the first time, the internal accumulation and external morphology of nanoparticles were precisely controlled "from top to bottom" by solution self-assembly, and single molecular weight fluorene-azobenzene amphiphilic copolymer nanofibers were obtained to construct 1D / 2D nanomaterials with special functions.

Claims

1. A single molecular weight fluorene-azobenzene amphiphilic oligomer precursor, the structure of which is shown below: ； ； 。 2. A single molecular weight fluorene-azobenzene amphiphilic oligomer, It is characterized in that The single molecular weight fluorene-azobenzene amphiphilic oligomer precursor of claim 1 is deprotected by Boc and then quaternized by hydrochloric acid to obtain the product.

3. The single molecular weight fluorene-azobenzene amphiphilic oligomer according to claim 2, It is characterized in that The Boc protection was removed using trifluoroacetic acid.

4. A method for self-assembly of a single molecular weight fluorene-azobenzene amphiphilic oligomer precursor in solution according to claim 1, It is characterized in that The method comprises the following steps: removing Boc protection from the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor and dissolving the precursor in a solvent, then adding water and hydrochloric acid, and standing to realize solution self-assembly of the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor; the solvent is tetrahydrofuran; the concentration of hydrochloric acid is 1 mol / L; the volume ratio of tetrahydrofuran, water and hydrochloric acid is 1:0.5:0.3-0.4; and standing at room temperature for 5 minutes to 24 hours.

5. A method for preparing a self-assembled fiber of a single molecular weight fluorene-azobenzene amphiphilic oligomer, It is characterized in that The method comprises the following steps: removing Boc protection from the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor 4F-4Azo according to claim 1, dissolving the precursor in a solvent, then adding water and hydrochloric acid, and standing to obtain single molecular weight fluorene-azobenzene amphiphilic oligomer self-assembled fibers; the solvent is tetrahydrofuran; the concentration of hydrochloric acid is 1 mol / L; the volume ratio of tetrahydrofuran, water, and hydrochloric acid is 1:0.5:0.3-0.4; and standing at room temperature for 5 minutes to 24 hours.

6. Self-assembled fibers of single molecular weight fluorene-azobenzene amphiphilic oligomers prepared according to the method of claim 5.

7. Use of the single molecular weight fluorene-azobenzene amphiphilic oligomer precursor according to claim 1 or the single molecular weight fluorene-azobenzene amphiphilic oligomer according to claim 2 in the preparation of nanofibers.

Images