AIE active naphthalene imide compound containing methylthio group and preparation method and application thereof

Abstract

The invention discloses an AIE active naphthalimide compound containing methylthio and its preparation method and application, and belongs to the field of fine chemical technology. Its preparation method comprises the following steps: a, 4-aminoaromatics and 4-bromo-1,8-naphthalic anhydride generate 4-bromo-1,8-naphthalimide derivatives under heating of anhydrous ethanol and post-processing conditions; b1, 4-bromo-1,8-naphthalimide derivatives and methylthiophenol, cesium carbonate are heated by acetonitrile and post-processing conditions to generate 1,8-naphthalimide derivatives containing methylthiophenol units at 4 positions; b2, 4-bromo-1,8-naphthalimide derivatives and methylthioaniline, cesium carbonate, bis(triphenylphosphine)palladium dichloride (II), triphenylphosphine generate 1,8-naphthalimide derivatives containing methylthioaniline units at 4 positions under heating of dry toluene and post-processing conditions. The invention has different spectra, and the luminescence is very weak in organic solvents such as tetrahydrofuran, but it shows strong green fluorescence and orange-red fluorescence in aggregated states such as aqueous solution and solid state, showing obvious aggregation-induced luminescence properties.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and in particular relates to an AIE-active naphthalimide compound containing a methylthio group, and a preparation method and application thereof. Background Art

[0002] Aggregation-induced emission (AIE) material is a new type of luminescent material. Based on mechanisms such as restricted intramolecular rotation, fluorophores can emit stronger fluorescence in the solid state or nano-aggregated state. Compared with traditional fluorescent materials, its development in the direction of fluorescent sensors, biological probes and organic light-emitting diodes has opened up new ways to broaden the scope of research and application areas. Through reasonable design strategies, traditional fluorescent materials can be converted into aggregation-induced emission materials, such as: introducing AIE active units (tetraphenylethylene, etc.) (Journal of the American Chemical Society, 2017, 139, 10150-10156), constructing intramolecular rotation centers (Chemical Engineering Journal, 2021, 415, 129095.), etc.

[0003] Naphthalimide (NI) is one of the most important fluorescent dyes. The imide fragment in its structure determines the electron-deficient nature of the molecule. By introducing electron-donating substituents of different strengths (such as amino, alkoxy, etc.) to its 4-position, the fluorescence emission wavelength of the molecule can be regulated to move to different regions. Among them, the stronger the donor property of the electron-donating unit, the stronger the charge transfer within the molecule, and the longer the fluorescence wavelength of the obtained compound. Based on the above advantages, naphthalimide fluorescent dyes are widely used in chemical sensors and fluorescent contrast agents. However, most classic NI dyes will undergo obvious non-radiative transitions in poor solvents or solid aggregates, resulting in strong fluorescence quenching.

[0004] In order to solve the adverse effects of NI fluorophores due to aggregation, several strategies have been reported. 1) Introducing a rotating core (Journal of Materials Chemistry, 2011, 21, 3170-3177.) 2) Connecting a large number of fragments to the NI chromophore (ACS Applied Materials & Interfaces, 2018, 10, 12081-12111.) 3) Optimizing the self-assembled structure of naphthalene imide (Angewandte Chemie International Edition, 2018, 57 (28), 8488-8492.). However, compared with their precursors and many other AIE active materials, it can be found that the implementation of the above strategies is often accompanied by an increase in molecular volume. Under similar luminescent properties, the increase in molecular volume undoubtedly reduces its atomic economy, does not conform to the concept of green chemistry, and is contrary to the current development trend of "carbon neutrality". Therefore, the development of more effective AIE regulation strategies and new AIE active naphthalene imide fluorophores has important technical development significance. Summary of the invention

[0005] The present invention proposes an AIE-active naphthaleneimide compound containing a methylthio group and a preparation method and application thereof, which has the characteristics of small molecular structure, simple synthesis, mild reaction conditions, and good aggregated luminescence performance, and is mainly achieved by the following technical scheme:

[0006] The AIE-active naphthalene imide compound containing a methylthio group is a compound represented by formula (I):

[0007]

[0008] in:

[0009] X = NH or O;

[0010]

[0011] Z=OH, COOH, NH2 or SH.

[0012] Preferably, said Y is

[0013] Preferably, the methylthio group is at the meta-position or the para-position.

[0014] The preparation method of the above-mentioned AIE active naphthalene imide compound containing methylthio group, the technical route is as follows:

[0015]

[0016] The following steps are involved:

[0017] a. 4-aminoaromatic hydrocarbon and 4-bromo-1,8-naphthalene dicarboxylic anhydride are heated in anhydrous ethanol to generate 4-bromo-1,8-naphthalene imide derivatives;

[0018] b1. 4-bromo-1,8-naphthalimide derivative, methylthiophenol and cesium carbonate are heated under acetonitrile to generate a 1,8-naphthalimide derivative containing a methylthiophenol unit at the 4-position, in which case X is 0; or

[0019] b2. 4-bromo-1,8-naphthalimide derivatives, methylthioaniline, cesium carbonate, bis(triphenylphosphine)palladium(II) dichloride and triphenylphosphine are heated in dry toluene and post-treated to generate 1,8-naphthalimide derivatives containing methylthioaniline units at the 4-position, where X is NH.

[0020] Preferably, in a, the molar volume ratio of 4-bromo-1,8-naphthalene dicarboxylic anhydride, 4-aminoaromatic hydrocarbon and ethanol is 1 mmol:1.1-1.5 mmol:2.22-2.77 mL; the reaction conditions are as follows: the heating reaction temperature is the reflux temperature, and the heating reaction time is 20-24 h; after the reaction is completed, it is cooled to room temperature, the precipitate is collected by filtration under reduced pressure, and the product is thoroughly dried.

[0021] Furthermore, in a, the molar volume ratio of the 4-bromo-1,8-naphthalene dicarboxylic anhydride, 4-aminoarene and ethanol is 1 mmol:1.5 mmol:2.77 mL.

[0022] Preferably, in b1, the molar volume ratio of the 4-bromo-1,8-naphthalimide derivative, methylthiophenol, cesium carbonate and acetonitrile is 1mmol:2.5~3mmol:0.5~0.75mmol:7~9mL; the reaction conditions are as follows: the heating reaction temperature is the reflux temperature, and the heating reaction time is 20~24h; after the reaction is completed, cool to room temperature, collect the precipitate by vacuum filtration, dry and use water to sonicate the solid, collect the precipitate by vacuum filtration, and the product is completely dried.

[0023] Furthermore, in b1, the molar volume ratio of the 4-bromo-1,8-naphthalimide derivative, methylthiophenol, cesium carbonate and acetonitrile is 1 mmol:3 mmol:0.75 mmol:9 mL.

[0024] Preferably, in b2, the molar volume ratio of the 4-bromo-1,8-naphthalimide derivative, methylthioaniline, cesium carbonate, bis(triphenylphosphine)palladium(II) dichloride, triphenylphosphine and dry toluene is 1mmol:1.1~1.15mmol:3~5mmol:0.1~0.16mmol:0.4~0.6mmol:8~10mL; the reaction conditions are: the reaction temperature is 100~120°C, the heating reaction time is 6~10h, nitrogen bubbling is used to remove oxygen during the reaction, after the reaction is completed, the solvent is evaporated under reduced pressure, extracted with water and dichloromethane, and the organic layer product is chromatographed on a silica gel column.

[0025] Furthermore, the molar volume ratio of the 4-bromo-1,8-naphthalimide derivative, methylthioaniline, cesium carbonate, bis(triphenylphosphine)palladium(II) dichloride, triphenylphosphine and dry toluene is 1 mmol:1.15 mmol:5 mmol:0.16 mmol:0.6 mmol:10 mL, and the reaction temperature is 110°C.

[0026] In steps (a), (b1) and (b2), stirring is performed during the reaction.

[0027] The above-mentioned AIE-active naphthalimide compound containing methylthio group is used to prepare fluorescent probe.

[0028] A fluorescent probe contains the above-mentioned AIE-active naphthalimide compound containing methylthio group.

[0029] The above-mentioned AIE-active naphthalimide compound containing methylthio group or the above-mentioned fluorescent probe is used to detect peroxide, and X is O.

[0030] The beneficial effects of the present invention are as follows: the naphthalimide compounds of the present invention use 1,8-naphthalene dicarboxamide as a fluorophore, N-aryl and methylphenyl sulfide as AIE activating groups, and introduce different heteroatoms at the 4-position to make them have different spectra. The series of compounds emit very weak light in organic solvents such as tetrahydrofuran, but show strong green fluorescence and orange-red fluorescence in aggregated states such as aqueous solution and solid state, showing obvious aggregation-induced emission properties.

[0031] Second, the preparation method of the present invention has the characteristics of small molecular structure, simple synthesis, mild reaction conditions, and good aggregated luminescence performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the solid fluorescence image of compound NIS1 in Example 1;

[0033] Figure 2 is a scanning electron microscope image of compound NIS1 in Example 1;

[0034] Figure 3 The time-dependent fluorescence emission spectrum of compound NIS1 in Example 1 after adding sodium hypochlorite solution under the condition of acetonitrile and water volume ratio of 1:1; wherein the excitation wavelength is 310nm, and the excitation / emission slit is 10 / 2nm;

[0035] Figure 4 It is a line graph of the fluorescence emission intensity ratio of compound NIS1 in Example 1 at corresponding time when the volume ratio of acetonitrile to water is 1:1;

[0036] Figure 5 The fluorescence emission spectrum of the compound NIS1 in Example 1 in a tetrahydrofuran solution with a water content of 0%-99%; wherein: the excitation wavelength is 365nm, and the excitation / emission slit is 5 / 5nm;

[0037] Figure 6 It is a line graph showing the ratio of the fluorescence emission intensity of the compound NIS1 in Example 1 in tetrahydrofuran solutions with different water contents;

[0038] Figure 7 is the 1H NMR spectrum of compound NIS1 in Example 1;

[0039] Figure 8 is a high-resolution mass spectrum of compound NIS1 in Example 1;

[0040] Fig. 9 is the solid fluorescence image of compound NIS2 in Example 2;

[0041] Fig.10 is a scanning electron micrograph of compound NIS2 in Example 2;

[0042] Fig.11 The fluorescence emission spectrum of the compound NIS2 in Example 2 in a THF solution with a water content of 0%-99%; wherein the excitation wavelength is 450nm, and the excitation / emission slit is 5 / 5nm;

[0043] Fig.12 It is a line graph showing the ratio of the fluorescence emission intensity of the compound NIS2 in Example 2 in tetrahydrofuran solutions with different water contents;

[0044] Fig.13 is the 1H NMR spectrum of compound NIS2 in Example 2;

[0045] Fig.14 is a high-resolution mass spectrum of compound NIS2 in Example 2;

[0046] Fig.15 This is the 1H NMR spectrum of compound NI in Example 1. DETAILED DESCRIPTION

[0047] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below in conjunction with specific embodiments.

[0048] Example 1

[0049] (I) Synthesizing reactant N1, the specific steps are as follows;

[0050] The synthesis of 4-bromo-1,8-naphthalimide derivatives is introduced by taking the synthesis of N-pyridine-4-bromo-1,8-naphthalimide (NI) as an example:

[0051]

[0052] At room temperature, 4-bromo-1,8-naphthalene dicarboxylic anhydride (10.00 g, 36.06 mmol) and 4-aminopyridine (5.09 g, 54.09 mmol) were dissolved in anhydrous ethanol (100 mL), and the resulting mixture was heated to reflux for 24 h. The resulting solution was cooled to room temperature and filtered under reduced pressure to collect the precipitate. The product was thoroughly dried to obtain compound NI as a brown powder (7.18 g, yield 56%).

[0053] 1 H NMR(400MHz,DMSO-d6)δppm 7.52(d,J=5.02Hz,2H)8.06(t,J=7.91Hz,1H)8.29(d,J=7.78Hz,1H)8.35-8.40(m,1H)8.63(dd,J=11.42,8.16Hz,2H)8.78(d,J=5.02Hz,2H);

[0054] (II) Synthesis of 1,8-naphthaleneimide-N-pyridine (NIS1) containing p-methylthiophenol unit at 4-position Introduction of the synthesis method of 4-phenoloxy-substituted naphthaleneimide compounds

[0055]

[0056] NI (1.77 g, 5 mmol) was dissolved in 45 mL of acetonitrile solution, and p-methylthiophenol (2.1 g, 15 mmol) and cesium carbonate (1.22 g, 3.75 mmol) were added, and the mixture was heated to reflux for 24 h. After the reaction was completed, the precipitate was collected by vacuum filtration, dried and the solid was sonicated with water, and the precipitate was collected by vacuum filtration. The product was thoroughly dried to obtain compound NIS1 as a green powder (1.65 g, yield 80%).

[0057] 1H NMR(400MHz,DMSO-d6)δppm 2.54(s,3H)7.06(d,J=8.28Hz,1H)7.30(d,J=8.53Hz,2H)7.45(d,J=8.53Hz,2H)7.51(d,J=4.52H z, 2H) 7.97 (t, J = 7.78Hz, 1H) 8.45 (d, J = 8.28Hz, 1H) 8.61 (d, J = 7.28Hz, 1H) 8.77 (d, J = 4.52Hz, 3H).

[0058] HRMS(m / z):([M+H] + )m / z:413.0960, found 413.0948.

[0059] from Figure 1 It can be seen that compound NIS1 emits green fluorescence at 500nm under excitation at 365nm.

[0060] from Figure 2 It can be seen that compound NIS1 has a micrometer-scale shuttle structure.

[0061] from Figure 5 and Figure 6 It can be seen that there is almost no emission in the water content range of 0-70%, and the fluorescence intensity gradually increases at 70-90%. In the range of 90-99%, the fluorescence gradually weakens due to the increase in the aggregation size of compound NIS1 and the decrease in dispersibility, indicating that compound NIS1 has aggregation-induced emission properties.

[0062] Compared with conventional 4-position oxygen-substituted naphthaleneimide, the strategy of introducing a sterically hindered phenol group at the 4-position of the NIS1 series dyes successfully achieved the construction of aggregation-induced emission naphthaleneimide molecules, indicating that the steric hindering unit helps to enhance the deplanarization effect of naphthaleneimide molecules when they aggregate.

[0063] from Figure 3 and Figure 4 It can be seen that when peroxide is added to the acetonitrile solution of compound NIS1, its fluorescence at 470nm shows an enhanced response, and the kinetic experiment shows that the fluorescence intensity increases nearly 3 times within 10 minutes. This shows that NIS1 has a recognition effect on peroxide and can be used for fluorescence detection of peroxide in organic solvents.

[0064] The peroxide fluorescence detection method is as follows: Application example: Peroxide (hypochlorous acid) detection

[0065] 1. Prepare 0.02M NaClO stock solution: take 50L of NaClO solution containing 7.5% active chlorine, place it in a 5mL volumetric flask, and add deionized water to make up to volume;

[0066] 2. Prepare the probe stock solution: Place NIS1 (2.1 mg, M 412.46 g / mol) in a 5 mL volumetric flask and dilute to a concentration of 1 × 10 -3 M probe stock solution;

[0067] 3. In a 1 cm quartz four-sided cuvette, add 990 L of deionized water and 990 L of acetonitrile, then pipette 20 L of the probe stock solution into the cuvette to obtain a sample containing 1 × 10 NIS1. -5 M solution;

[0068] 4. Place the cuvette in the fluorescence spectrometer, set the excitation wavelength to 310nm, and the excitation / emission slits to 10 / 2nm respectively. The scanning range is 330nm~650nm, and the fluorescence spectrum of NIS1 is obtained;

[0069] 5. Take out the above cuvette, add 10L of 0.02M NaClO solution, scan the fluorescence spectrum every 5 minutes, record for 120 minutes, and obtain the fluorescence emission spectrum of the kinetic response of NIS1 to hypochlorous acid (such as Figure 3 shown);

[0070] 6. Make a scatter plot of the fluorescence intensity at 470nm in the above spectrum against time to obtain the dynamic fluorescence intensity change diagram at the maximum emission point ( Figure 4 shown).

[0071] Embodiment 2:

[0072] (I) Synthesis of reactant NI

[0073] The steps are the same as those in Example 1 (I).

[0074] (II) The synthesis of 1,8-naphthaleneimide-N-pyridine (NIS2) containing m-methylthioaniline unit at the 4-position is introduced to introduce the synthesis method of arylamine-substituted naphthaleneimide compounds:

[0075]

[0076] In a 100mL flask, NI (1.77g, 5mmol) was dissolved in dry toluene (50mL), and then m-methylthioaniline (800mg, 5.75mmol), cesium carbonate (8.14g, 25mmol), bis(triphenylphosphine)palladium (II) dichloride (560mg, 0.8mmol), and triphenylphosphine (785mg, 3mmol) were added in sequence. The mixture was heated at 110°C for 8h under a nitrogen atmosphere. After the reaction was completed, the solvent was evaporated under reduced pressure, and the mixture was extracted with water and dichloromethane. The organic layer product was chromatographed on a silica gel column to obtain compound NIS2 as a dark orange solid (1.12g, yield 54%).

[0077] 1 H NMR(400MHz,DMSO-d6)δppm 1.36(s,3H)7.09(d,J=8.03Hz,1H)7.21(d,J=7.78Hz,1H)7.27(s,1H)7.32-7.42(m,2H)7.48(d,J=4.77Hz,2H)7.82- 7.90 (m, 1H) 8.32 (d, J = 8.28Hz, 1H) 8.53 (d, J = 7.03Hz, 1H) 8.76 (d, J = 4.77Hz, 2H) 8.87 (d, J = 8.53Hz, 1H) 9.48 (s, 1H).

[0078] HRMS(m / z):[M+H] + Cald:412.1114; found:412.1110.

[0079] Depend on Fig. 9 It can be seen that compound NIS2 emits orange fluorescence at 600 nm under excitation at 365 nm.

[0080] Depend on Fig.10 It can be seen that compound NIS2 also shows an ordered structure at the micrometer scale, and its microsize is smaller than that of NIS1.

[0081] Depend on Fig.11 and Fig.12 It can be seen that when the water content is in the range of 0-80%, the fluorescence at 540nm gradually decreases; when the water content is in the range of 90-99%, the fluorescence at 600nm gradually increases. This indicates that the compound NIS2 undergoes aggregation-induced quenching when the water content is low, and when the aggregation reaches a certain level, the aggregate luminescence is generated, and the luminescence performance is enhanced.

[0082] Depend on Fig.11 It can be seen that the emission peak of NIS2 in the molecular state is located at 540nm. After forming aggregates, the emission wavelength moves to the long wave to 600nm.

[0083] Compared with conventional 4-nitrogen-substituted naphthaleneimide, the NIS2 series dyes successfully achieved the construction of aggregation-induced emission naphthaleneimide molecules by introducing a sterically hindered aromatic amine group at the 4-position, indicating that the steric hindering unit helps to enhance the deplanarization effect of naphthaleneimide molecules when they aggregate.

[0084] Table 1 Optical properties of compounds NIS1 and NIS2 in different solvents

[0085]

[0086] As shown in Table 1, the N-linked compounds have higher fluorescence efficiency and larger Stokes shift and emission wavelength than the O-linked compounds.

[0087] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. AIE-active naphthalimide compound containing methylthio group, characterized in that : The compounds are NIS1 and NIS2; the structural formula of NIS1 is: The structural formula of the NIS2 is:

2. The method for preparing the AIE-active naphthalimide compound containing a methylthio group according to claim 1, characterized in that: N-pyridine-4-bromo-1,8-naphthalimide and 4-methylthiophenol are heated to generate NIS1 in claim 1, and the reaction conditions are: adding N-pyridine-4-bromo-1,8-naphthalimide, 4-methylthiophenol, and cesium carbonate, reacting under heating conditions of acetonitrile, and the molar volume ratio of N-pyridine-4-bromo-1,8-naphthalimide, 4-methylthiophenol, cesium carbonate and acetonitrile is 1mmol:2.5~3mmol:0.5~0.75mmol:7~9mL, and reacting at reflux temperature for 20-24h; or, N-pyridine-4-bromo-1,8-naphthalimide and m-methylthioaniline are heated to generate NIS2 in claim 1, and the reaction conditions are: N-pyridine-4-bromo-1,8-naphthalimide, m-methylthioaniline, cesium carbonate, bis(triphenylphosphine)palladium(II) dichloride, and triphenylphosphine are reacted under heating with dry toluene, and the molar volume ratio of N-pyridine-4-bromo-1,8-naphthalimide, m-methylthioaniline, cesium carbonate, bis(triphenylphosphine)palladium(II) dichloride, triphenylphosphine and dry toluene is 1mmol:1.1~1.15mmol:3~5mmol:0.1~0.16mmol:0.4~0.6mmol:8~10mL; the reaction temperature is 100~120℃, and the heating time is 6~10h.

3. The preparation method according to claim 2, characterized in that: The preparation method of N-pyridine-4-bromo-1,8-naphthalimide comprises the following steps: 4-aminopyridine and 4-bromo-1,8-naphthalene dicarboxylic anhydride are heated under anhydrous ethanol to generate N-pyridine-4-bromo-1,8-naphthalene dicarboxylic anhydride; the reaction conditions are: the molar volume ratio of the 4-bromo-1,8-naphthalene dicarboxylic anhydride, 4-aminopyridine and ethanol is 1 mmol:1.1-1.5 mmol:2.22-2.77 mL; and heating at reflux temperature for 20-24 hours.

4. Use of the AIE-active naphthalimide compound containing a methylthio group according to claim 1 in preparing a fluorescent probe, characterized in that: The AIE-active naphthaleneimide compound containing a methylthio group is NIS1, and the fluorescent probe is used to detect hypochlorous acid.

5. A fluorescent probe, characterized in that A methylthio-containing AIE-active naphthalimide compound according to claim 1, wherein the methylthio-containing AIE-active naphthalimide compound is NIS1.

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