Imidazo [1, 2-alpha] pyridine stimuli-responsive molecule with D-A twisted structure as well as preparation method and application of imidazo [1, 2-alpha] pyridine stimuli-responsive molecule

Abstract

The invention provides an imidazo [1, 2-alpha] pyridine stimuli-responsive molecule with a D-A twisted structure as well as a preparation method and application of the imidazo [1, 2-alpha] pyridine stimuli-responsive molecule, belongs to the technical field of intelligent materials, and is used for solving the technical problem that intelligent materials for developing stimuli-responsive molecules for data encryption and information anti-counterfeiting are insufficient. The preparation method of the compounds N1 and N3 comprises the following steps: 2-aminopyridine and 2, 4 '-dibromoacetophenone are subjected to an amphiphilic reaction to obtain a compound a; the compound a and POCl3 are subjected to a Vilsmeier-Haack reaction, and a compound b is obtained; carrying out Suzuki coupling reaction on the compound a or the compound b and triphenylamine boric acid to obtain a compound N1 or N2; the compound N2 and malononitrile are subjected to a Knovenagel condensation reaction, and a compound N3 is obtained. The compound prepared in the invention has good fluorescence emission capability in a solution and a solid state and a grinding solvent acid / alkali stimulated fluorescence discoloration behavior, and can realize good data encryption and information anti-counterfeiting.

Description

Technical Field

[0001] The present invention belongs to the technical field of smart materials, and in particular relates to a stimulus-responsive molecule. Background Art

[0002] In nature, all life forms can sense external stimuli and adapt their characteristics accordingly to their environment. Inspired by this, people hope to design artificial systems that can sense and / or respond to external stimuli in a predictable and controllable manner. Stimuli-responsive materials, generally a new class of functional materials, can reversibly change their physical or chemical properties in response to one or more triggers, such as light, electricity, heat, magnetism, pressure, pH, ions, or other molecules. As a result, stimuli-responsive materials have gradually become promising candidates for various cutting-edge fields such as data storage, molecular machines, sensing, drug delivery, and smart coatings, and will become the core of future intelligent technologies. To date, the numerous reports on stimuli-responsive materials have not only promoted the design of new materials, the development of synthesis methods, and characterization techniques, but also enabled researchers to fundamentally understand the interaction between stimuli and materials. Therefore, this has prompted researchers to explore how to construct excellent new stimuli-responsive materials with simple methods and low costs to ensure their widespread application in practice. The DA-type structure has donor-acceptor capabilities due to its strong electron-donating ability, allowing intramolecular charge transfer processes. Its twisted dihedral angle has a large rotation space and can undergo conformational changes when exposed to different mechanical forces, including pressure, friction or stretching. It is often used to construct stimulus-responsive systems.

[0003] Imidazolopyridine derivatives are a unique class of nitrogen-containing fused-ring compounds widely used in medicine due to their exceptional biological activities. Their pharmacological actions include antimitotic, antituberculosis, and antiviral properties, and they also act as antagonists for several receptors. Beyond their physiological significance, rational structural modification can transform them into novel stimuli-responsive building blocks. Summary of the Invention

[0004] In response to the technical problem of insufficient smart materials for developing stimulus-responsive molecules for data encryption and information anti-counterfeiting, the present invention proposes a DA-distorted structured imidazo[1,2-α]pyridine stimulus-responsive molecule, its preparation method, and application. The prepared compound has good fluorescence emission ability in solution and solid state, as well as fluorescence color change behavior stimulated by acid / base in grinding solvents, which can achieve good data encryption and information anti-counterfeiting.

[0005] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A DA-distorted imidazo[1,2-α]pyridine stimuli-responsive molecule, wherein the imidazo[1,2-α]pyridine stimuli-responsive molecule is N1 or N3, and the structural formula is as follows:

[0007]

[0008] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the method for preparing the imidazo[1,2-α]pyridine stimulus-responsive molecules N1 and N3 comprises the following steps:

[0009] (1) 2-aminopyridine, 2,4'-dibromoacetophenone, catalyst I, and solvent I are mixed to undergo a dinucleophilic reaction to obtain compound a;

[0010] (2) Compound a, POCl3 and solvent II are mixed to undergo a Vilsmeier-Haack reaction to obtain compound b;

[0011] (3) Compound a or compound b, triphenylamine borate, base I, catalyst II, and solvent III are mixed to undergo a Suzuki coupling reaction to obtain compound N1 or N2;

[0012] (4) Compound N2, malononitrile, catalyst III, base II and solvent IV are mixed to undergo Knovenagel condensation reaction to obtain compound N3.

[0013] In the step (1), the catalyst I is sodium bicarbonate, potassium tert-butoxide, zinc chloride, pyridine or triethylamine; and the solvent I is ethanol, N,N-dimethylformamide, dichloromethane or acetonitrile.

[0014] The molar ratio of the 2-aminopyridine, 2,4'-dibromoacetophenone and catalyst I is 1:0.5-2:0.1-2; the ratio of the 2-aminopyridine to the solvent I is 1:1-5 mmol / ml; the temperature of the dinucleophilic reaction is 70-90°C and the time is 6-24 hours.

[0015] In step (2), solvent II is N,N-dimethylformamide, chloroform, toluene or N-methylpyrrolidone; the molar ratio of compound a and POCl3 is 1:0.5-2; the ratio of compound a to solvent II is 1:1-5mmol / ml; the temperature of the Vilsmeier-Haack reaction is 50-70°C and the time is 1-6h.

[0016] In the step (3), the catalyst II is a palladium catalyst; the palladium catalyst is tetrakistriphenylphosphine palladium or dichlorobis(triphenylphosphine)palladium; the base I is potassium carbonate, sodium carbonate, potassium tert-butoxide or sodium hydroxide; and the solvent III is any one or more of toluene, dichloromethane, N,N-dimethylformamide, dioxane or water.

[0017] The molar ratio of compound a or compound b, triphenylamine borate, base I and catalyst II is 1:0.5-2:1-5:0.01-0.1; the ratio of compound a or compound b to solvent III is 1:10-30 mmol / ml; the temperature of the Suzuki coupling reaction is 80-120°C, and the time is 12-36 hours.

[0018] In the step (4), the base II is pyridine or piperidine; the catalyst III is titanium tetrachloride; and the solvent IV is ethanol, methanol, dichloromethane or N,N-dimethylformamide.

[0019] The molar ratio of the compound N2, malononitrile, catalyst III and base II is 1:2-4:2-3:10-20; the ratio of the compound N2 to the solvent IV is 1:10-20 mmol / ml; the temperature of the Knovenagel condensation reaction is 30-50°C and the time is 3-6 hours.

[0020] The present invention relates to an application of a DA-distorted imidazo[1,2-α]pyridine-type stimuli-responsive molecule in data encryption and information anti-counterfeiting. Stimuli-responsive materials have many applications in the field of smart materials, such as data encryption and information anti-counterfeiting. Triphenylamine is often used in stimuli-responsive molecules that change color upon grinding and change color upon solvatochromism due to its electron-donating ability and propeller-shaped conformation. A suitable receptor structure is also an important part of adjusting the charge transfer within the molecule. The stimuli-responsive molecule has good fluorescence emission properties in the original solid state and solution state. Grinding or solvent or acid / base stimulation can significantly change the fluorescence emission color and quantum yield, and the above process has a good recycling effect. The DA-distorted imidazo[1,2-α]pyridine-type stimuli-responsive molecule of the present invention has good fluorescence color change behavior upon grinding, solvent and acid / base stimulation.

[0021] Beneficial effects of the present invention:

[0022] The present invention provides two novel DA-distorted imidazo[1,2-α]pyridine stimuli-responsive molecules, and it is found that they have good fluorescence emission behavior in solution and solid state. The above-mentioned stimuli-responsive molecules are subjected to grinding force to prepare different solid states of DA-distorted imidazo[1,2-α]pyridine compounds. The above-mentioned solid states have different emission colors and wavelengths under fluorescence. Moreover, when the original solid state is fumigated with acid, its fluorescence color will rapidly and significantly red-shift, and will return to the original fluorescence color after re-fumigation with alkali. The above-mentioned stimuli-responsive molecules are dissolved in solutions of different polarities and prepared into dilute solutions. Under fluorescence, they will show obvious red-shift changes with changes in polarity. The polarity parameters of different solvents have a good linear relationship with the fluorescence wavelength in different solvents. After reasonable design, they have the ability to encrypt data and prevent information counterfeiting. This has potential application value for actual data encryption and information counterfeiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 This is the H NMR spectrum of the stimulus-responsive molecule N1.

[0025] Figure 2 This is the carbon NMR spectrum of the stimulus-responsive molecule N1.

[0026] Figure 3 High-resolution mass spectrometry of the stimulus-responsive molecule N1.

[0027] Figure 4 This is the H NMR spectrum of the stimulus-responsive molecule N3.

[0028] Figure 5 This is the carbon NMR spectrum of the stimulus-responsive molecule N3.

[0029] Figure 6 High-resolution mass spectrometry of the stimuli-responsive molecule N3.

[0030] Figure 7 UV-visible absorption spectra of the stimuli-responsive molecule N1 in different solid states.

[0031] Figure 8 The normalized fluorescence emission spectra of the stimulus-responsive molecule N1 in different solid states are shown in the inset. The fluorescence images before and after grinding are shown in the inset.

[0032] Figure 9 UV-visible absorption spectra of the stimulus-responsive molecule N3 in different solid states.

[0033] Figure 10 The normalized fluorescence emission spectra of the stimulus-responsive molecule N3 in different solid states are shown in the inset. The fluorescence images before and after grinding are shown in the inset.

[0034] Figure 11 UV-visible absorption spectra of the stimuli-responsive molecule N1 (10 μM) in solvents of different polarities.

[0035] Figure 12 Normalized fluorescence spectra of the stimuli-responsive molecule N1 (10 μM) in solvents of different polarities. The inset shows the fluorescence colors in different solvents.

[0036] Figure 13 is the linear relationship between the polarity parameters of different solvents and the fluorescence wavelength in different solvents.

[0037] Figure 14 The solid-normalized emission fluorescence spectrum of the acidochromic state is shown, and the inset shows the fluorescence colors of different states.

[0038] Figure 15 This is a graph showing the number of cycles of acid-induced discoloration.

[0039] Figure 16 Data encryption pattern based on solvatochromic properties.

[0040] Figure 17 Information anti-counterfeiting pattern made based on the acid-induced color change property. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0042] Example 1

[0043] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N1 is:

[0044]

[0045] The general reaction formula is:

[0046]

[0047] Preparation method: 2-aminopyridine (2 g, 21.25 mmol), 2,4'-dibromoacetophenone (4.92 g, 17.71 mmol), and sodium bicarbonate (2.23 g, 26.55 mmol) were placed in a round-bottom flask, 50 mL of ethanol was added, and the mixture was refluxed at 80°C for 12 hours. After the reaction, the mixture was poured into an appropriate amount of water and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to obtain a slightly yellow solid (4.0 g, 74.78%). 1 H NMR (600MHz, CDCl3) δ8.12(d,J=6.7Hz,1H),7.86(s,1H),7.83(d,J=8.4Hz,2H),7.6 3(d,J=9.1Hz,1H),7.56(d,J=8.3Hz,2H),7.22-7.15(m,1H),6.80(t,J=6.7Hz,1H).

[0048]

[0049] The preparation method is as follows: 2-(4-bromophenyl)imidazo[1,2-a]pyridine (1g, 3.6mmol), triphenylamine borate (1.4g, 3.6mmol), tetrakistriphenylphosphine palladium (210mg, 0.18mmol) and potassium carbonate (1.5g, 11mmol) are weighed into a Schlenk flask, and after replacing N2 three times, 90mL of solvent (toluene / water = 8 / 2) is added and the mixture is reacted at 100°C for 24h. After the reaction is completed, water is added to quench the mixture, and the mixture is extracted with dichloromethane (50mL×3 times). The organic phases are combined, dried over anhydrous Na2SO4, and separated by column chromatography (petroleum ether / ethyl acetate) to obtain a slightly yellow solid, which is compound N1 (1.1g, 70.50%). NMR and mass spectrometry are as follows Figure 1-3 As shown, 1 H NMR (600MHz, CDCl3) δ8.14(d,J=6.7Hz,1H),8.01(d,J=8.3Hz,2H),7.90(s,1H),7.66(t,J=7.8Hz,3H),7.54(d,J=8.6Hz, 2H),7.28(d,J=8.0Hz,4H),7.20-7.17(m,1H),7.15(dd,J=8.1,4.2Hz,6H),7.04(t,J=7.3Hz,2H),6.79(t,J=6.7Hz,1H). 13C NMR (151MHz, CDCl3) δ147.70,147.28,145.78,145.62,140.12,134.67,132.29,129.30,127.61,126 .87,126.45,125.56,124.64,124.45,123.94,122.96,117.57,112.43,108.11.HRMS(ESI)m / zcalcd for[C31H24N3 + ]438.1965([M+H] + ); found 438.1965.

[0050] Example 2

[0051] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N3 is:

[0052]

[0053] The general reaction formula is:

[0054]

[0055] Compound b was prepared by weighing a (100 mg, 0.37 mmol) into a reaction flask. DMF (1.2 mL) was added dropwise under an ice bath, followed by the addition of POCl₃ (34.20 μL). The reaction was incubated at 60°C for 2 h. After completion of the reaction, the mixture was quenched by pouring into a large amount of ice water, stirred overnight, and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na₂SO₄, and separated by column chromatography (petroleum ether / ethyl acetate) to afford a slightly yellow solid (113.0 mg, 97.54%). 1 HNMR (400MHz, CDCl3) δ10.05(s,1H),9.73-9.58(m,1H),7.81(d,J=8.9Hz,1H),7.76-7.64(m,4H),7.64-7.57(m,1H),7.15(td,J=6.9,1.2Hz,1H).

[0056]

[0057] Compound N2 was prepared by placing compound b (1.5 g, 5 mmol), triphenylamine borate (1.84 g, 5 mmol), tetrakistriphenylphosphine palladium (0.29 g, 0.25 mmol), and potassium carbonate (2.07 g, 15 mmol) in a Schlenk flask. Under an argon atmosphere, 72 mL of toluene and 18 mL of aqueous solution were added. The system was reacted at 100°C for 24 h. After the reaction, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate = 2 / 1) to yield a yellow solid, compound N2 (1.32 g, 56.6%). 1 HNMR (600MHz, CDCl3) δ10.14(s,1H),9.69(d,J=6.8Hz,1H),7.90(d,J=8.3Hz,2H),7.83(d,J=8.9Hz,1H),7.75(d,J =8.3Hz,2H),7.62-7.58(m,1H),7.54(t,J=9.8Hz,2H),7.32-7.27(m,4H),7.19-7.12(m,7H),7.06(t,J=7.4Hz,2H). 13 C NMR (151MHz, CDCl3) δ179.52, 158.04, 147.84 (d, J = 7.6Hz), 147.57, 142.14, 133.75, 130.72, 130.42, 130. 26,129.35,128.87,127.81,126.98,124.65,123.65,123.19,120.82,117.43,115.24.HRMS(ESI)m / zcalcd for[C32H24N3O + ]466.1914([M+H] + ),found466.1918.

[0058] The general reaction formula is:

[0059]

[0060] The preparation method of compound N3 is as follows: N2 (400 mg, 0.72 mmol) is placed in a three-necked flask to replace N2, and then 5 mL of dichloromethane is added at 0°C, followed by 5 mL of dichloromethane-dissolved malononitrile (140 mg, 2.12 mmol), and then 4 mL of dichloromethane-dissolved titanium tetrachloride (335.71 mg, 1.77 mmol), and after stirring for 30 minutes, pyridine (726.93 mg, 9.19 mmol) is added dropwise, and then an appropriate amount of CH2Cl2 is added. After completion, the mixture is reacted at 40°C for 5 hours. After the reaction is completed, water is added, and the mixture is extracted with dichloromethane (10 mL × 3 times). The organic phases are combined, dried over anhydrous Na2SO4, and separated by column chromatography (petroleum ether / ethyl acetate) to obtain an orange solid, which is compound N3 (208.2 mg, 57%). Nuclear magnetic resonance and mass spectrometry are as follows Figure 4-6 As shown, 1 HNMR (600MHz, CDCl3) δ8.54(d,J=6.9Hz,1H),7.95(s,1H),7.87(d,J=8.9Hz,1H),7.76(dd,J=20.0,8.3Hz,4H ),7.66-7.63(m,1H),7.56(d,J=8.6Hz,2H),7.32-7.27(m,5H),7.17(t,J=7.6Hz,6H),7.06(t,J=7.4Hz,2H). 13 C NMR (151MHz, CDCl3) δ157.25,150.21,148.03,147.52,143.64,142.73,133.32,130.62,130.17,129.38,12 8.95,127.85,127.25,124.74,123.52,123.29,118.60,116.98,115.07(d,J=4.3Hz),113.85.HRMS(ESI)m / z calcd for[C35H24N5 + ]514.2026([M+H] + ),found 514.2021.

[0061] Example 3

[0062] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N1 is:

[0063]

[0064] The general reaction formula is:

[0065]

[0066] Compound a was prepared by placing 2-aminopyridine (10 mmol), 2,4'-dibromoacetophenone (5 mmol), and potassium tert-butoxide (10 mmol) in a round-bottom flask, adding 50 mL of ethanol, and reflux at 90°C for 6 hours. After the reaction, the mixture was poured into an appropriate amount of water and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a slightly yellow solid.

[0067] The general reaction formula is:

[0068]

[0069] The DA-structured imidazo[1,2-α]pyridine stimuli-responsive compound N1 was prepared by placing compound a (10 mmol), triphenylamine borate (5 mmol), dichlorobis(triphenylphosphine)palladium (1 mmol), and sodium carbonate (10 mmol) in a Schlenk flask. Under an argon atmosphere, 82 mL of N,N-dimethylformamide and 18 mL of aqueous solution were added. The system was reacted at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a slightly yellow solid, compound N1.

[0070] Example 4

[0071] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N1 is:

[0072]

[0073] The general reaction formula is:

[0074]

[0075] Compound a was prepared by placing 2-aminopyridine (10 mmol), 2,4'-dibromoacetophenone (20 mmol), and potassium tert-butoxide (20 mmol) in a round-bottom flask, adding 30 mL of ethanol, and reflux at 70°C for 24 hours. After the reaction, the mixture was poured into an appropriate amount of water and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a slightly yellow solid.

[0076] The general reaction formula is:

[0077]

[0078] The DA-structured imidazo[1,2-α]pyridine-based stimuli-responsive compound N1 was prepared by placing compound a (10 mmol), triphenylamine borate (10 mmol), dichlorobis(triphenylphosphine)palladium (0.1 mmol), and sodium hydroxide (50 mmol) in a Schlenk flask. Under an argon atmosphere, 82 mL of N,N-dimethylformamide and 18 mL of aqueous solution were added. The system was reacted at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a slightly yellow solid, compound N1.

[0079] Example 5

[0080] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N1 is:

[0081]

[0082] The general reaction formula is:

[0083]

[0084] Compound a was prepared by placing 2-aminopyridine (10 mmol), 2,4'-dibromoacetophenone (20 mmol), and potassium tert-butoxide (1 mmol) in a round-bottom flask, adding 10 mL of ethanol, and refluxing at 80°C for 12 hours. After the reaction, the mixture was poured into an appropriate amount of water and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a slightly yellow solid.

[0085] The general reaction formula is:

[0086]

[0087] The DA-structured imidazo[1,2-α]pyridine-based stimuli-responsive compound N1 was prepared by placing compound a (10 mmol), triphenylamine borate (20 mmol), dichlorobis(triphenylphosphine)palladium (0.5 mmol), and sodium hydroxide (30 mmol) in a Schlenk flask. Under an argon atmosphere, 160 mL of N,N-dimethylformamide and 40 mL of aqueous solution were added. The system was reacted at 120°C for 12 hours. After the reaction, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a slightly yellow solid, compound N1.

[0088] Example 6

[0089] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N3 is:

[0090]

[0091] The general reaction formula is:

[0092]

[0093] Compound b was prepared by weighing a (1 mmol) into a reaction flask. N-methylpyrrolidone (5 mL) was added dropwise to the mixture under an ice bath, followed by the dropwise addition of POCl₃ (46.20 μL). The reaction was incubated at 70°C for 1 h. After completion of the reaction, the mixture was quenched by pouring it into a large amount of ice water, stirred overnight, and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na₂SO₄, and separated by column chromatography (petroleum ether / ethyl acetate) to yield the product.

[0094] The general reaction formula is:

[0095]

[0096] Compound N2 was prepared by placing compound b (10 mmol), triphenylamine borate (5 mmol), dichlorobis(triphenylphosphine)palladium (1 mmol), and sodium carbonate (10 mmol) in a Schlenk flask. Under an argon atmosphere, 82 mL of N,N-dimethylformamide and 18 mL of an aqueous solution were added. The system was reacted at 80°C for 36 hours. After the reaction, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to obtain a slightly yellow solid, Compound N2.

[0097] The general reaction formula is:

[0098]

[0099] The preparation method for the DA-distorted imidazo[1,2-α]pyridine-based stimuli-responsive compound N3 is as follows: 10 mmol of N2 is placed in a three-necked flask to displace the N2. Then, 50 mL of dichloromethane is added at 0°C, followed by 20 mmol of malononitrile dissolved in 50 mL of dichloromethane and 20 mmol of titanium tetrachloride dissolved in 40 mL of dichloromethane. After stirring for 30 minutes, pyridine (100 mmol) is added dropwise, followed by an appropriate amount of CH2Cl2. The mixture is reacted at 40°C for 5 hours. After completion of the reaction, water is added, and the mixture is extracted with dichloromethane (50 mL x 3). The combined organic phases are dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield an orange solid, compound N3.

[0100] Example 7

[0101] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N3 is:

[0102]

[0103] The general reaction formula is:

[0104]

[0105] Compound b was prepared by weighing a (1 mmol) into a reaction flask. N-methylpyrrolidone (3 mL) was added dropwise to the mixture under an ice bath, followed by the dropwise addition of POCl₃ (184.8 μL). The reaction was incubated at 70°C for 1 h. After completion of the reaction, the mixture was quenched by pouring it into a large amount of ice water, stirred overnight, and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na₂SO₄, and separated by column chromatography (petroleum ether / ethyl acetate) to obtain the product.

[0106]

[0107] Compound N2 was prepared by placing compound b (10 mmol), triphenylamine borate (10 mmol), dichlorobis(triphenylphosphine)palladium (0.1 mmol), and sodium hydroxide (50 mmol) in a Schlenk flask. Under an argon atmosphere, 82 mL of N,N-dimethylformamide and 18 mL of an aqueous solution were added. The system was reacted at 80°C for 36 hours. After completion of the reaction, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield a yellow solid, Compound N2.

[0108] The general reaction formula is:

[0109]

[0110] The preparation method for the DA-distorted imidazo[1,2-α]pyridine-based stimuli-responsive compound N3 is as follows: 10 mmol of N2 is placed in a three-necked flask to displace the N2. Then, 50 mL of ethanol is added at 0°C, followed by 20 mmol of malononitrile dissolved in 50 mL of ethanol, and 30 mmol of titanium tetrachloride dissolved in 40 mL of ethanol. After stirring for 30 minutes, piperidine (100 mmol) is added dropwise, followed by an appropriate amount of ethanol. The mixture is reacted at 40°C for 5 hours. After completion of the reaction, water is added, and the mixture is extracted with dichloromethane (500 mL x 3). The combined organic phases are dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield an orange solid, compound N3.

[0111] Example 8

[0112] A method for preparing a DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule, wherein the structural formula of compound N3 is:

[0113]

[0114] The general reaction formula is:

[0115]

[0116] Compound b was prepared by weighing a (5 mmol) into a reaction flask. N-methylpyrrolidone (5 mL) was added dropwise under an ice bath, followed by the addition of POCl₃ (462 μL). The reaction was incubated at 50°C for 6 h. After completion of the reaction, the mixture was quenched by pouring into a large amount of ice water, stirred overnight, and extracted with dichloromethane (30 mL x 3). The combined organic phases were dried over anhydrous Na₂SO₄, and separated by column chromatography (petroleum ether / ethyl acetate) to yield the product.

[0117]

[0118] Compound N2 was prepared by placing compound b (10 mmol), triphenylamine borate (20 mmol), dichlorobis(triphenylphosphine)palladium (0.5 mmol), and sodium hydroxide (30 mmol) in a Schlenk flask. Under an argon atmosphere, 160 mL of N,N-dimethylformamide and 40 mL of an aqueous solution were added. The system was reacted at 120°C for 12 hours. After the reaction was completed, the mixture was cooled to room temperature, the excess organic solvent was removed under reduced pressure, and the mixture was extracted with dichloromethane (20 mL x 3). The combined organic phases were dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to obtain a yellow solid, Compound N2.

[0119] The general reaction formula is:

[0120]

[0121] The preparation method for the DA-distorted imidazo[1,2-α]pyridine-based stimuli-responsive compound N3 is as follows: 10 mmol of N2 is placed in a three-necked flask to displace the N2. Then, 50 mL of dichloromethane is added at 0°C, followed by 40 mmol of malononitrile dissolved in 50 mL of dichloromethane, and 30 mmol of titanium tetrachloride dissolved in 40 mL of dichloromethane. After stirring for 30 minutes, pyridine (200 mmol) is added dropwise, followed by an appropriate amount of CH2Cl2. The reaction is allowed to proceed at 40°C for 5 hours. After completion of the reaction, water is added, and the mixture is extracted with dichloromethane (50 mL x 3). The combined organic phases are dried over anhydrous Na2SO4 and separated by column chromatography (petroleum ether / ethyl acetate) to yield an orange solid, compound N3.

[0122] The DA twisted imidazo[1,2-α]pyridine stimuli-responsive molecules N1 and N3 were characterized by preparing the DA twisted imidazo[1,2-α]pyridine stimuli-responsive molecules in Examples 1 and 2. The solid fluorescence of the DA twisted imidazo[1,2-α]pyridine stimuli-responsive molecules was significantly red-shifted under the action of grinding force ( Figure 7-10 The imidazo[1,2-α]pyridine stimuli-responsive molecule N1 based on the DA twisted structure has a good solvatochromic effect. The fluorescence emission spectra of compound N1 in different solvents were detected ( Figure 11 and Figure 12 The polarity parameters of different solvents have a good linear relationship with the fluorescence wavelength ( Figure 13 When N1 solid is fumigated with acid, the fluorescence color undergoes a huge red shift of 148nm. And fumigation with alkali can restore the original fluorescence color, and this cycle can be repeated 5 times without damaging the material. Figure 14 and Figure 15 ). Using solvatochromic properties ( Figure 16 ) and acidochromic properties ( Figure 17 ) is a data encryption and information anti-counterfeiting application produced by .

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A DA-distorted imidazo[1,2-α]pyridine stimuli-responsive molecule, characterized in that: The imidazo[1,2-α]pyridine stimuli-responsive molecules include compounds N1 and N3, and the structural formulas are shown below:

2. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 1, characterized in that: The preparation method of imidazo[1,2-α]pyridine stimulus-responsive molecules N1 and N3 comprises the following steps: (1) 2-aminopyridine, 2,4'-dibromoacetophenone, catalyst I, and solvent I are mixed to undergo a dinucleophilic reaction to obtain compound a; (2) Compound a, POCl3 and solvent II are mixed to undergo a Vilsmeier-Haack reaction to obtain compound b; (3) Compound a or compound b, triphenylamine borate, base I, catalyst II, and solvent III are mixed to undergo a Suzuki coupling reaction to obtain compound N1 or N2; (4) Compound N2, malononitrile, catalyst III, base II and solvent IV are mixed to undergo Knovenagel condensation reaction to obtain compound N3.

3. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 2, characterized in that: In the step (1), the catalyst I is sodium bicarbonate, potassium tert-butoxide, zinc chloride, pyridine or triethylamine; and the solvent I is ethanol, N,N-dimethylformamide, dichloromethane or acetonitrile.

4. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 3, characterized in that: The molar ratio of the 2-aminopyridine, 2,4'-dibromoacetophenone and catalyst I is 1:0.5-2:0.1-2; the ratio of the 2-aminopyridine to the solvent I is 1:1-5 mmol / ml; the temperature of the dinucleophilic reaction is 70-90°C and the time is 6-24 hours.

5. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to any one of claims 2 to 4, characterized in that: In step (2), solvent II is N,N-dimethylformamide, chloroform, toluene or N-methylpyrrolidone; the molar ratio of compound a and POCl3 is 1:0.5-2; the ratio of compound a to solvent II is 1:1-5mmol / ml; the temperature of the Vilsmeier-Haack reaction is 50-70°C and the time is 1-6h.

6. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 5, characterized in that: In the step (3), the catalyst II is a palladium catalyst; the palladium catalyst is tetrakistriphenylphosphine palladium or dichlorobis(triphenylphosphine)palladium; the base I is potassium carbonate, sodium carbonate, potassium tert-butoxide or sodium hydroxide; and the solvent III is toluene, dichloromethane, N,N-dimethylformamide, dioxane or water.

7. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 6, characterized in that: The molar ratio of compound a or compound b, triphenylamine borate, base I and catalyst II is 1:0.5-2:1-5:0.01-0.1; the ratio of compound a or compound b to solvent III is 1:10-30 mmol / ml; the temperature of the Suzuki coupling reaction is 80-120°C, and the time is 12-36 hours.

8. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 7, characterized in that: In the step (4), the base II is pyridine or piperidine; the catalyst III is titanium tetrachloride; and the solvent IV is ethanol, methanol, dichloromethane or N,N-dimethylformamide.

9. The method for preparing the DA-distorted imidazo[1,2-α]pyridine stimulus-responsive molecule according to claim 8, characterized in that: The molar ratio of the compound N2, malononitrile, catalyst III and base II is 1:2-4:2-3:10-20; the ratio of the compound N2 to the solvent IV is 1:10-20 mmol / ml; the temperature of the Knovenagel condensation reaction is 30-50°C and the time is 3-6 hours.

10. Use of the DA-distorted imidazo[1,2-α]pyridine stimuli-responsive molecule according to claim 1 in data encryption and information anti-counterfeiting.

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