A coumarin-based pressure-induced fluorescent color-changing material and its synthesis method and application

Abstract

The present invention discloses a coumarin-based piezofluorescent material having the structural formula shown in Formula (I). The synthesis method comprises dispersing the compound CM-1, p-trifluoromethylbenzaldehyde, and potassium carbonate in anhydrous ethanol, heating under reflux, and column chromatography to obtain the target product CM-CF3. The raw materials are readily available, the synthesis route is simple, the conditions are mild, and the yield is high. The coumarin-based piezofluorescent material of the present invention exhibits fluorescence emission properties in both the single-molecule state and the solid powder state. Furthermore, in the solid powder state, it exhibits significant piezofluorescent color changes in response to grinding pressure, with the fluorescence switching between yellow and orange. The material can be applied to pressure sensors, information displays, anti-counterfeiting trademarks, and other fields. #imgabs0#

Description

Technical Field

[0001] The present invention belongs to the technical field of organic fluorescent materials, and in particular relates to a coumarin-based piezo-fluorescent material and a synthesis method and application thereof. Background Art

[0002] Organic fluorescent materials have attracted considerable attention due to their modifiable structures, easily tunable emission wavelengths, and wide-ranging applications. Over the past decade, researchers have discovered and studied a new type of organic fluorescent "smart material," mechanofluorochromic materials (MFCs). Their spatial structure can be altered by external mechanical forces (such as grinding, squeezing, or stretching), leading to changes in their photophysical properties. Because changes in their spatial structure are physical processes, their photophysical properties are reversible. MFC materials have been applied to pressure sensors, information displays, and anti-counterfeiting trademarks. Summary of the Invention

[0003] The purpose of the present invention is to provide a coumarin-based piezofluorescent material, which exhibits fluorescence emission in both dilute solution and solid powder states. In the solid powder state, it shows obvious piezofluorescent properties in response to grinding pressure. The material can be applied to pressure sensors, information displays, anti-counterfeiting trademarks and other fields.

[0004] To achieve the above object, the technical solution adopted by the present invention is to provide a coumarin-based piezofluorescent material having the structural formula shown in formula (I):

[0005]

[0006] Among the many chromophores, the coumarin group is a blue-light fluorescent chromophore with an excellent rigid planar structure and a π-conjugated structure. Therefore, it has the characteristics of high fluorescence quantum yield, excellent photostability, and easy structural regulation in dilute solutions. Therefore, the present invention selects coumarin as the parent structure, and by building a phenylacetyl group on the coumarin parent, expanding the π-conjugated structure, introducing the electron-withdrawing trifluoromethyl group, and regulating the charge flow within the molecule, a new organic fluorescent material that exhibits fluorescence emission in both the single molecule state and the solid powder state is obtained, enriching the application field of fluorescent materials. In the solid powder state, the material exhibits obvious pressure-induced fluorescence color change properties in response to grinding pressure, and can be applied to the fields of pressure sensors, information displays, and anti-counterfeiting trademarks.

[0007] Another object of the present invention is to provide a method for synthesizing a coumarin-based pressure-induced fluorescent chromic material. To achieve this technical purpose, the technical solution adopted by the present invention is to provide a method for synthesizing a coumarin-based pressure-induced fluorescent chromic material, specifically: dispersing compound CM-1, p-trifluoromethylbenzaldehyde and potassium carbonate in anhydrous ethanol, heating and refluxing until the reaction is completed, and purifying by column chromatography to obtain the target product CM-CF3.

[0008]

[0009] Furthermore, the molar ratio of CM-1 to p-trifluoromethylbenzaldehyde is 1:(1.1-1.3).

[0010] Furthermore, the amount of ethanol added was based on CM-1, and 10 to 15 mL of ethanol was added to 1 mmol of CM-1.

[0011] Furthermore, the amount of potassium carbonate added is based on CM-1, and 1.1 to 1.3 mmol of potassium carbonate is added to 1 mmol of CM-1.

[0012] The synthesis method of the present invention involves synthesizing the target molecule CM-CF3 through an aldol condensation reaction of an aldehyde-containing coumarin derivative (CM-1) and a benzaldehyde derivative under alkaline conditions. The raw materials are readily available, the synthesis route is simple, and the conditions are mild. By incorporating phenylacetyl and trifluoromethyl groups into the coumarin matrix, a new piezo-chromic fluorescent material is obtained.

[0013] Another object of the present invention is to provide an application of a coumarin-based pressure-induced fluorescent color-changing material. In the solid powder state, CM-CF3 exhibits obvious pressure-induced fluorescent color-changing properties in response to grinding pressure. Under grinding pressure and solvent fumigation treatment, the fluorescence achieves a reversible conversion between yellow and orange, and can be applied to pressure sensors, information displays, anti-counterfeiting trademarks and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum of the coumarin-based pressure-induced fluorescent color-changing material CM-CF3 of the present invention.

[0015] Figure 2 This is the nuclear magnetic resonance carbon spectrum of the coumarin-based pressure-induced fluorescent color-changing material CM-CF3 of the present invention

[0016] Figure 3 This is a single crystal structure diagram of the coumarin-based piezochromic material CM-CF3 of the present invention.

[0017] Figure 4 The present invention discloses ultraviolet-visible absorption and fluorescence spectra of the coumarin-based piezofluorescent material CM-CF3 in different solvents.

[0018] Figure 5 It is the ultraviolet-visible absorption spectrum and fluorescence spectrum of the coumarin-based piezo-fluorescent material CM-CF3 in the aggregated state of the present invention.

[0019] Figure 6 It is the piezo-fluorescence color change spectrum and XRD diagram of the coumarin-based piezo-fluorescence color change material CM-CF3 of the present invention.

[0020] Figure 7 This is a SEM image of the coumarin-based piezofluorescent material CM-CF3 of the present invention. DETAILED DESCRIPTION

[0021] The following examples are provided to further illustrate the present invention but are not intended to limit the present invention.

[0022] A method for synthesizing a coumarin-based piezofluorescent material CM-CF3, specifically comprising:

[0023] Disperse the aldehyde-containing coumarin derivative CM-1 (0.50 g, 1.49 mmol), p-trifluoromethylbenzaldehyde (0.31 g, 1.79 mmol) and potassium carbonate (0.25 g, 1.79 mmol) in 15 mL of ethanol, raise the temperature to reflux, monitor the reaction by TLC until completion, cool to room temperature, filter, and perform column chromatography (petroleum ether: CH2Cl2=1:1, V / V) to obtain a yellow solid product CM-CF3 (0.56 g, 1.14 mmol) in a yield of 76%. FT-IR (KBr, cm -1 ):3063,2982,2927,2880,1712,1661,1620,1590,1518,1417,1354,1321,1215,1195,1167,1120,1065,1026,1010,982,823,710,629,594,535,469. 1 H NMR (400MHz, CDCl3) δ: 8.07 (d, J = 8.44Hz, 2H), 7.89 (d, J = 8.44Hz, 2H), 7.83 ( d,J=15.72Hz,1H),7.82(s,1H),7.76(d,J=8.20Hz,2H),7.69(d,J=8.28Hz,2H ),7.62(d,J=15.76Hz,1H),7.36(d,J=8.84Hz,1H),6.62(dd,J=8.40,2.40Hz ,1H),6.54(d,J=2.28Hz,1H),3.44(q,J=7.12Hz,4H),1.24(t,J=7.08Hz,6H). 13C NMR(101MHz, CDCl3)δ:189.51,161.31,156.55,151.07,142.68,141.58,14 0.78,138.34,136.55,131.70,129.39,128.70,128.56,128.36,125.64(q,J C-F =4Hz),124.30,119.07,109.23,108.92,97.03,44.95,12.49.ESI-MS:m / z=492.1750([M+H] + ),calcd for C 29 H 25 F3NO3 + =492.1787([M+H] + ).

[0024]

[0025] Take 20 mg of the yellow solid compound CM-CF3 and dissolve it in 5 mL of dichloromethane, filter it into a test tube, and then slowly add a small amount of ethanol to cover its surface. Slowly evaporate the solvent at room temperature to obtain a yellow single crystal. Figure 3 The single crystal structure shows a monoclinic system with a space group of P21 / c. CM-CF3 molecules are stacked via intermolecular hydrogen bonds (CH···O, CH···F) and π-π interactions, exhibiting a layered "V" stacking pattern. This stacking pattern effectively reduces intermolecular π-π stacking interactions, reduces non-radiative transition pathways, and enables fluorescence emission in the solid powder state.

[0026] from Figure 4 It can be clearly seen that in different organic solvents (c=1.0×10 -5 mol L -1 ), the UV-visible absorption peak of the compound CM-CF3 is mainly distributed around 425nm, which is mainly derived from the intramolecular charge transfer of the entire organic conjugated molecule. At the same time, the molar absorption coefficient of this peak exceeds 3.0×10 4 L cm -1 mol -1, indicating that the transition of electrons from lower-energy molecular orbitals to higher-energy molecular orbitals is a transition-allowed process. The fluorescence emission spectrum clearly shows that CM-CF3 exhibits strong fluorescence intensity in the non-polar solvent benzene. As the solvent polarity increases, the fluorescence intensity decreases, accompanied by a red-shift in the fluorescence peak. This is because the compound CM-CF3 contains an electron-donating 4-diethylamino group and an electron-withdrawing trifluoromethyl group, leading to a significant intramolecular charge transfer process. The polarity of the excited state is greater than that of the ground state, so polar solvents cause the energy level of the excited state to decrease more than that of the ground state, thereby reducing the energy difference between the excited and ground states and increasing non-radiative transition pathways. Consequently, the emission peak intensity decreases and the peak position shifts to longer wavelengths.

[0027] from Figure 5 As can be seen in the figure, when the water content in tetrahydrofuran exceeds 70%, the absorbance of the compound CM-CF3 begins to decline rapidly, and the baseline exhibits a significant "drift," indicating that the molecules are undergoing significant aggregation. The fluorescence spectrum shows that the fluorescence intensity of the compound CM-CF3 initially decreases with increasing water content, but then increases significantly with molecular aggregation, indicating that the compound CM-CF3 exhibits significant fluorescence emission in both the single-molecule and aggregated states. The single crystal structure reveals that while some π-π interactions exist, these interactions are weak. The intermolecular stacking occurs through hydrogen bonding, which inhibits single-bond rotations within the molecule and weakens non-radiative transitions, resulting in the fluorescence emission properties.

[0028] After grinding the compound CM-CF3, it was found that the fluorescence emission peak of the original sample was 549nm, which is a yellow emission. After grinding, the peak was red-shifted to 579nm, which is orange emission. The fluorescence peak was red-shifted by 30nm. Figure 6 From the powder XRD test, it was found that the compound showed strong and sharp diffraction peaks in its original state, indicating that the molecule showed good crystallinity. After pressure grinding, most of the diffraction peaks were significantly weakened, and even some of the diffraction peaks disappeared, indicating that the stacking pattern of the molecules had changed significantly, and its stacking changed from a regular crystalline state to a disordered state. Figure 7 The SEM image of the compound CM-CF3 clearly shows that in its original state, the compound is a layered, strip-shaped crystalline state. However, after thorough grinding, the molecules clearly exhibit an amorphous state, confirming the transition between crystalline and amorphous states. The above data show that the material CM-CF3 exhibits fluorescence emission in both dilute solution and aggregated states. In the solid powder state, it exhibits significant piezo-induced fluorescence color change in response to grinding pressure, primarily due to changes in the stacking structure. Given its exceptional photophysical properties, this material has potential applications in pressure sensors, information displays, and anti-counterfeiting trademarks.

Claims

1. A coumarin-based piezofluorescent material, characterized in that: It has the structural formula shown in formula (I):

2. The method for synthesizing the coumarin-based piezofluorescent material according to claim 1, characterized in that: Specifically: Disperse compound CM-1, p-trifluoromethylbenzaldehyde and potassium carbonate in anhydrous ethanol, heat to reflux, monitor by thin layer chromatography until the reaction is complete, cool to room temperature, filter and purify to obtain the target product CM-CF3; The structure of compound CM-1 is shown as:

3. The method for synthesizing a coumarin-based piezofluorescent material according to claim 2, wherein: The molar ratio of compound CM-1 to p-trifluoromethylbenzaldehyde is 1:(1.1-1.3).

4. The method for synthesizing a coumarin-based piezofluorescent material according to claim 2, wherein: The amount of potassium carbonate added was based on compound CM-1, and 1.1 to 1.3 mmol of potassium carbonate was added to 1 mmol of compound CM-1.

5. The method for synthesizing a coumarin-based piezofluorescent material according to claim 2, wherein: The amount of anhydrous ethanol added was based on compound CM-1: 10-15 mL of anhydrous ethanol was added to 1 mmol of compound CM-1.

6. Use of the coumarin-based piezofluorescent material according to claim 1 in anti-counterfeiting labels.

7. Use of the coumarin-based piezofluorescent material according to claim 1 in pressure sensing.

8. Use of the coumarin-based piezofluorescent material according to claim 1 in information display.

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