A molecular probe modified by vanillin, its preparation method and application

Abstract

The present invention provides a vanillin-modified molecular probe, a preparation method thereof and an application. First, a dehydrating agent dispersion liquid and a vanillin solution are successively mixed with a Meldrum's acid dispersion liquid, and then a Knoevenagel condensation reaction is carried out to obtain the vanillin-modified molecular probe. The vanillin-modified molecular probe provided by the present invention has stable chemical properties, can still stably exist in a complex beauty emulsion, the signal release is not easily interfered, the sensitivity to viscosity is higher than other factors, and it can maintain good photostability in solutions with various polarities and various pH values.

Description

Technical Field

[0001] The present invention relates to the technical field of beauty analysis and detection technologies, and in particular to a molecular probe modified with vanillin, a preparation method thereof, and an application thereof. Background Art

[0002] With people's yearning for a better life, "appearance value" products have gradually become one of the essential consumer goods for the general public. Beauty products have become an essential tool for enhancing "appearance value", not only being a necessary consumption expenditure for female consumers, but also becoming part of the expenditure of male consumers in recent years. In fact, the consumption in this field is extremely large. Among them, as a key component of the three major categories of traditional beauty products, namely "lotion, milk, and cream", lotion is widely used for coating the face or other parts of the body. The spreading and wetting degree on the skin will profoundly affect the consumer experience, and these performances are closely related to the consistency. Sometimes, manufacturers even adjust the consistency to improve the texture of beauty lotion, enabling consumers to have a better texture experience when using it. Thus, it can be seen that in the process of preparing beauty lotion, the control of consistency is crucial, and its essence is related to the micro-region viscosity of beauty lotion. Micro-region viscosity, a property that can reflect the resistance of a fluid to deformation or prevent the relative flow of adjacent fluid layers, is a physical parameter that has a profound connection with the apparent performances such as the spreading, wetting, and covering of beauty lotion. The change in the consistency of beauty lotion is often internal and difficult to precisely define apparently. In contrast, micro-region viscosity can be measured and even precisely defined. However, traditional viscosity measurements mostly rely on various viscometers (falling ball viscometer, rotational viscometer, vibrating viscometer, etc.). These viscometers are designed for macroscopic viscosity, highly dependent on equipment during measurement, and require a large volume of samples for measurement. More importantly, it is difficult to achieve molecular-level measurement of microscopic viscosity.

[0003] In the field of beauty detection technology, photochemical technology has advantages such as sensitive response, convenient use, in-situ imaging, and real-time imaging. In particular, this method can measure micro-region viscosity with the help of molecular-level tools. This way can achieve fast visual observation of the micro-region viscosity of beauty lotion, which is of crucial significance for the improvement of the process of beauty lotion (consistency), especially for the enhancement of performances such as the spreading, wetting, and coating of lotion. Therefore, it is of great significance to develop a molecular probe modified with vanillin and a preparation method thereof for the detection of the viscosity of beauty lotion. Summary of the Invention

[0004] The purpose of the present invention is to provide a molecular probe modified with vanillin, a preparation method thereof, and an application thereof, so as to solve the technical problem in the prior art that it is difficult to accurately measure the micro-region viscosity of beauty lotion.

[0005] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a molecular probe modified based on vanillin, and the molecular probe has a structure shown in Formula I:

[0007]

[0008] The present invention provides a preparation method of a molecular probe modified based on vanillin. The dehydrating agent dispersion liquid and the vanillin solution are successively mixed with the Meldrum's acid dispersion liquid, and then a Knoevenagel condensation reaction is carried out to obtain the molecular probe modified based on vanillin.

[0009] Preferably, the dehydrating agent dispersion liquid is composed of a dehydrating agent and a solvent, wherein the dehydrating agent comprises one or more of sodium carbonate, calcium hydroxide, sodium bicarbonate, cesium carbonate, potassium carbonate, potassium bicarbonate, magnesium hydroxide, calcium carbonate, calcium acetate and tin acetate.

[0010] Preferably, the vanillin solution is composed of vanillin and a solvent; the Meldrum's acid dispersion liquid is composed of Meldrum's acid and a solvent; the solvent independently comprises one or more of tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, ethanol, dimethyl sulfoxide and methanol.

[0011] Preferably, the content of the dehydrating agent in the dehydrating agent dispersion liquid is 1-150 mol / L; the concentration of the vanillin solution is 1-300 mol / L; the content of Meldrum's acid in the Meldrum's acid dispersion liquid is 1-15 mol / L.

[0012] Preferably, the molar ratio of the dehydrating agent, Meldrum's acid and vanillin is 1-150:1:1-20.

[0013] Preferably, the temperature of the Knoevenagel condensation reaction is 20-100 °C, and the time is 1-96 h.

[0014] The present invention provides an application of a molecular probe modified based on vanillin in detecting the viscosity of beauty milk. It can be achieved by mixing the molecular probe modified based on vanillin and the beauty milk, and the mixing concentration of the molecular probe modified based on vanillin is 5-15 μmol / L.

[0015] The molecular probe modified with vanillin according to the present invention contains a freely rotatable single-double bond conjugated structure. This conjugated structure exhibits a certain flexibility and can freely mechanically rotate in a beauty emulsion with a low viscosity. The excited-state energy can be dissipated through mechanical motion, and the intensity of the finally released optical signal is weak, indicating that the beauty emulsion is thin and has good coating and spreading effects. As the beauty emulsion gradually thickens, the mechanical rotation of the molecular probe modified with vanillin in the beauty emulsion becomes increasingly difficult. Its excited-state energy instead consumes in the form of radiative transition, and the intensity of the released optical signal is high, and this is a gradually increasing state. The intensity of the optical signal will gradually increase as the viscosity of the beauty product gradually rises, that is, a "turn-on" visual imaging effect can be achieved. Based on this, the molecular probe can be used as a tool for regulating the thickness process of beauty emulsions, and the blending of its thickness can be visually monitored through the intensity of the released optical signal. The molecular probe modified with vanillin according to the present invention can emit strong fluorescence at 540 - 800 nm under external excitation at 500 - 520 nm, and can measure the viscosity of the beauty emulsion, thereby further judging its thickness and providing data reference for process development.

[0016] Advantages of the present invention:

[0017] (1) The molecular probe modified with vanillin provided by the present invention is obtained by further modifying the natural product vanillin. The molecular probe is prepared by a one-step method. The required raw materials are rich in sources and are natural plant extracts, with low prices. The overall application preparation cost is low, and the whole process does not require complex preparation processes, is suitable for large-scale preparation, and the final yield is also high. The process is relatively green and environmentally friendly, meeting the concept of low-carbon sustainable development.

[0018] (2) The molecular probe modified with vanillin provided by the present invention can achieve visual imaging of beauty emulsions with different viscosities and can be used for the preparation process and thickness control of beauty emulsions.

[0019] (3) The molecular probe modified with vanillin provided by the present invention has stable chemical properties, can still stably exist in complex beauty emulsions, the signal release is not easily interfered, is more sensitive to viscosity than other factors, and can maintain good photostability in solutions with various polarities and various pH values. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the mechanism for detecting the viscosity of a beauty emulsion by the molecular probe modified with vanillin provided by the present invention;

[0021] Figure 2 It is the mass spectrum of the molecular probe modified with vanillin prepared in Example 1;

[0022] Figure 3Fluorescence spectra of the vanillin-modified molecular probe prepared in Example 1 in a series of glycerol / water mixed solutions;

[0023] Figure 4 Graph of the logarithmic function of the fluorescence intensity of the vanillin-modified molecular probe prepared in Example 1 versus the viscosity value;

[0024] Figure 5 Graph of the photostability test of the vanillin-modified molecular probe prepared in Example 1 in high-viscosity and low-viscosity solutions;

[0025] Figure 6 Absorption spectra of the vanillin-modified molecular probe prepared in Example 1 in solutions of different polarities;

[0026] Figure 7 Emission spectra of the vanillin-modified molecular probe prepared in Example 1 in solutions of different pH values;

[0027] Figure 8 Emission spectra of the vanillin-modified molecular probe prepared in Example 1 in different commercially available beauty lotions. Detailed implementation mode

[0028] The present invention provides a vanillin-modified molecular probe, and the molecular probe has a structure shown in Formula I:

[0029]

[0030] The name of the vanillin-modified molecular probe of the present invention is 5-(4-hydroxy-3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (HMBDDD), and its molecular formula is C 14 H 14 O6, and the relative molecular mass is 278.08. This molecular probe is obtained by further modification based on the natural product vanillin (Formula II). It is a light yellow (off-white) powder and is easily soluble in various common solvents such as ethyl acetate, methanol, ethanol, N,N-dimethylformamide, tetrahydrofuran, and dimethyl sulfoxide. This molecular probe has good aromaticity, good photostability, stable chemical structure and can be stored for a long time, low hygroscopicity and is not easy to deteriorate. Its molecular structure has freely rotatable conjugated single and double bonds, presenting a typical flexible conjugated structure. The conjugated structure can rotate freely in dilute solutions and is restricted in thick solutions, converting into optical signals for release, making the control of the entire thickness visible. And it will not be affected by the main components of emulsions such as common surfactants, various beauty aids (such as niacinamide, palmitic acid, isopropyl isostearate, etc.), and enzymes, so it is particularly suitable for the determination of the viscosity of beauty lotions.

[0031] The vanillin has the structure shown in Formula II:

[0032]

[0033] The present invention provides a preparation method of a molecular probe modified based on vanillin. A dehydrating agent dispersion liquid and a vanillin solution are sequentially mixed with a Meldrum's acid dispersion liquid, and then a Knoevenagel condensation reaction is carried out to obtain the molecular probe modified based on vanillin.

[0034] In the present invention, the dehydrating agent dispersion liquid is composed of a dehydrating agent and a solvent, wherein the dehydrating agent includes one or more of sodium carbonate, calcium hydroxide, sodium bicarbonate, cesium carbonate, potassium carbonate, potassium bicarbonate, magnesium hydroxide, calcium carbonate, calcium acetate and tin acetate, preferably one or more of sodium carbonate, calcium hydroxide, potassium carbonate, sodium bicarbonate and calcium carbonate, and further preferably one or more of sodium carbonate, potassium carbonate and calcium carbonate.

[0035] The function of using the dehydrating agent in the present invention is to remove the water generated during the reaction and promote the reaction to proceed to the right.

[0036] In the present invention, the vanillin solution is composed of vanillin and a solvent; the Meldrum's acid dispersion liquid is composed of Meldrum's acid and a solvent; the solvent independently includes one or more of tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, ethanol, dimethyl sulfoxide and methanol, preferably one or more of N,N-dimethylformamide, ethyl acetate, ethanol and methanol, and further preferably one or more of ethyl acetate, ethanol and methanol.

[0037] In the present invention, the content of the dehydrating agent in the dehydrating agent dispersion liquid is 1 to 150 mol / L, preferably 10 to 130 mol / L, and further preferably 50 to 100 mol / L; the concentration of the vanillin solution is 1 to 300 mol / L, preferably 30 to 200 mol / L, and further preferably 50 to 150 mol / L; the content of Meldrum's acid in the Meldrum's acid dispersion liquid is 1 to 15 mol / L, preferably 2 to 12 mol / L, and further preferably 3 to 10 mol / L.

[0038] In the present invention, the molar ratio of the dehydrating agent, Meldrum's acid and vanillin is 1 to 150:1:1 to 20, preferably 5 to 120:1:2 to 15, and further preferably 10 to 110:1:3 to 12.

[0039] In the present invention, when the dehydrating agent dispersion liquid is mixed with the Meldrum's acid dispersion liquid, it is preferably carried out by dropwise addition, and the dropping rate is 1 drop / s to 10 drops / s, preferably 2 drops / s to 9 drops / s, and further preferably 3 drops / s to 8 drops / s.

[0040] In the present invention, when mixing the dehydrating agent dispersion and the Meldrum's acid dispersion, it is preferably carried out under stirring conditions. The stirring rate is 100 - 1000 rpm, preferably 200 - 800 rpm, and more preferably 300 - 700 rpm; the stirring time is 1 - 24 h, preferably 5 - 20 h, and more preferably 10 - 15 h.

[0041] In the present invention, the temperature of the Knoevenagel condensation reaction is 20 - 100 °C, preferably 40 - 80 °C, and more preferably 50 - 70 °C; the time is 1 - 96 h, preferably 10 - 90 h, and more preferably 20 - 80 h.

[0042] In the present invention, at the initial stage of the Knoevenagel condensation reaction, it needs to be carried out in an inert atmosphere, where the inert atmosphere includes a helium atmosphere, an argon atmosphere, a neon atmosphere or a krypton atmosphere, preferably a helium atmosphere, an argon atmosphere or a neon atmosphere, and more preferably a helium atmosphere or an argon atmosphere.

[0043] In the present invention, the equation of the Knoevenagel condensation reaction is as follows:

[0044]

[0045] In the present invention, after the Knoevenagel condensation reaction, it is preferably to purify the Knoevenagel condensation reaction product. The purification process preferably sequentially carries out reduced-pressure distillation, extraction, concentration, chromatography and drying on the reaction product. Among them, the reduced-pressure distillation is carried out in a rotary evaporator, and the pressure of the rotary evaporator is -0.09 MPa to -0.08 MPa, preferably -0.085 MPa; in the extraction process, a mixed system of ethyl acetate and deionized water is preferably used, and the volume ratio of ethyl acetate to deionized water is 1 - 10:1, preferably 2 - 8:1, and more preferably 4 - 6:1; the concentration is to further dry the solution obtained after extraction with anhydrous Na2SO4, and then use a rotary evaporator to remove the dried solution; during chromatography, a silica gel chromatographic column is preferably used to further purify the obtained crude product, and the purification process is carried out in a methanol / ethyl acetate mixed system, and the volume ratio of methanol to ethyl acetate is 1:1 - 10, preferably 1:2 - 8, and more preferably 1:4 - 6; during drying, vacuum drying is preferably used, and the temperature of the vacuum drying is 30 - 60 °C, preferably 35 - 55 °C, and more preferably 40 - 50 °C; the time of the vacuum drying is 1 - 36 h, preferably 5 - 30 h, and more preferably 10 - 20 h.

[0046] The present invention provides an application of a vanillin-modified molecular probe in detecting the viscosity of beauty milk. It only needs to mix the vanillin-modified molecular probe and beauty milk. The mixing concentration of the vanillin-modified molecular probe is 5-15 μmol / L, preferably 8-12 μmol / L, and further preferably 10 μmol / L.

[0047] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0048] Example 1

[0049] Dissolve 10 mmol of vanillin in ethanol and stir evenly to obtain a vanillin solution with a concentration of 10 mol / L. Disperse 2 mmol of Meldrum's acid in ethanol and stir evenly to obtain a Meldrum's acid dispersion with a Meldrum's acid content of 2 mol / L. Disperse 100 mmol of calcium carbonate in ethanol to obtain a calcium carbonate dispersion with a calcium carbonate content of 100 mol / L. Add the calcium carbonate dispersion to the Meldrum's acid dispersion at a dropping rate of 3 drops / s, mix at 25 °C, control the stirring rate at 800 rpm, and stir for 18 h. After mixing evenly, pour it into the vanillin solution and carry out the Knoevenagel condensation reaction in a helium atmosphere. The reaction temperature is 60 °C and the reaction time is 24 h.

[0050] Purify the reaction product of the Knoevenagel condensation reaction. The purification process is carried out in sequence of vacuum distillation, extraction, concentration, chromatography and drying. The vacuum distillation is carried out in a rotary evaporator to remove the remaining reaction solvent under the condition of a pressure of -0.09 MPa. Then use a mixed system of ethyl acetate and deionized water for extraction, where the volume ratio of ethyl acetate to deionized water is 8:1. The obtained organic solvent layer is dried with anhydrous Na2SO4 and then the dried solution is removed with a rotary evaporator. Then, the obtained crude product is further purified by a silica gel chromatographic column. The purification process is carried out in a methanol / ethyl acetate mixed system (methanol / ethyl acetate, V / V = 1:3). Finally, it is dried in a vacuum oven at 50 °C for 24 h to obtain 478.16 mg of powder, which is the vanillin-modified molecular probe, denoted as HMBDDD, and the yield is 86%.

[0051] The vanillin-modified molecular probe prepared in Example 1 was subjected to high-resolution mass spectrometry detection, and the results are as Figure 2 shown. As Figure 2 can be seen, the relative molecular mass of the vanillin-modified molecular probe prepared in Example 1 is 279.20903 [M+H] +, its theoretical relative mass estimated value is 278.07904, and it can be determined that the synthesized product is the molecular probe 5-(4-hydroxy-3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxolane-4,6-dione modified from natural products, having the structural formula shown in Formula I, and the molecular formula of Formula I is C 14 H 14 O6.

[0052] Example 2

[0053] Dissolve 1 mmol of vanillin in methanol and stir evenly to obtain a vanillin solution with a concentration of 1 mol / L. Disperse 1 mmol of Meldrum's acid in methanol and stir evenly to obtain a Meldrum's acid dispersion with a Meldrum's acid content of 1 mol / L. Disperse 1 mmol of sodium carbonate in methanol to obtain a sodium carbonate dispersion with a sodium carbonate content of 1 mol / L. Add the sodium carbonate dispersion to the Meldrum's acid dispersion at a dropping rate of 1 drop / s, mix at 25 °C, control the stirring rate at 1000 rpm, and stir for 1 h. After mixing evenly, pour it into the vanillin solution and carry out the Knoevenagel condensation reaction in a neon atmosphere. The reaction temperature is 20 °C and the reaction time is 96 h.

[0054] Purify the reaction product of the Knoevenagel condensation reaction. The purification process is carried out in sequence of vacuum distillation, extraction, concentration, chromatography and drying. Among them, vacuum distillation is carried out in a rotary evaporator to remove the remaining reaction solvent under the condition of a pressure of -0.08 MPa; then use a mixed system of ethyl acetate and deionized water for extraction, where the volume ratio of ethyl acetate to deionized water is 1:1. The obtained organic solvent layer is dried with anhydrous Na2SO4, and then the dried solution is removed with a rotary evaporator; then the obtained crude product is further purified by a silica gel chromatographic column. The purification process is carried out in a methanol / ethyl acetate mixed system (methanol / ethyl acetate, V / V = 1:1). Finally, it is dried in a vacuum oven at 60 °C for 1 h to obtain 227.9 mg of powder, which is the molecular probe modified based on vanillin, denoted as HMBDDD, and the yield is 82%.

[0055] The mass spectrometry results of the molecular probe modified based on vanillin prepared in Example 2 are the same as those obtained in Example 1.

[0056] Example 3

[0057] Dissolve 30 mmol of vanillin in methanol and stir evenly to obtain a vanillin solution with a concentration of 300 mol / L. Disperse 1.5 mmol of Meldrum's acid in methanol and stir evenly to obtain a Meldrum's acid dispersion with a Meldrum's acid content of 15 mol / L. Disperse 225 mmol of potassium carbonate in methanol to obtain a potassium carbonate dispersion with a potassium carbonate content of 150 mol / L. Add the potassium carbonate dispersion to the Meldrum's acid dispersion at a dropping rate of 10 drops / s, mix at 25 °C, control the stirring rate at 100 rpm, and stir for 24 h. After mixing evenly, pour it into the vanillin solution and carry out the Knoevenagel condensation reaction in a neon atmosphere. The reaction temperature is 100 °C and the reaction time is 1 h.

[0058] Purify the reaction product of the Knoevenagel condensation reaction. The purification process is carried out in sequence of vacuum distillation, extraction, concentration, chromatography and drying. Among them, vacuum distillation is carried out in a rotary evaporator to remove the remaining reaction solvent under the condition of a pressure of -0.085 MPa. Then use a mixed system of ethyl acetate and deionized water for extraction, where the volume ratio of ethyl acetate to deionized water is 10:1. The obtained organic solvent layer is dried with anhydrous Na2SO4, and then the dried solution is removed with a rotary evaporator. Then, the obtained crude product is further purified by a silica gel chromatographic column. The purification process is carried out in a methanol / ethyl acetate mixed system (methanol / ethyl acetate, V / V = 1:10). Finally, it is dried in a vacuum oven at 30 °C for 48 h to obtain 333.6 mg of powder, which is the molecular probe modified based on vanillin, denoted as HMBDDD, and the yield is 80%.

[0059] The mass spectrometry results of the molecular probe modified based on vanillin prepared in Example 3 are the same as those obtained in Example 1.

[0060] Application Example 1

[0061] Dissolve 5.56 mg of the molecular probe modified based on vanillin prepared in Example 1 in a certain volume of DMF, control the concentration at 2 mmol / L, and then add the solution of the molecular probe modified based on vanillin to 3 common different beauty lotions respectively. Control the mixing concentration of the molecular probe modified based on vanillin at 10 μmol / L and test at 25 °C. Control the excitation wavelength of the external light source at 520 nm. The test results are as Figure 8 shown.

[0062] From Figure 8It can be seen that the light signal release intensities of these three beauty lotions are different, indicating that there are certain viscosity differences among these three beauty lotions. This may be related to the different components contained in the beauty lotions. From the final test results of the three beauty lotions, beauty lotion 1 belongs to a low-viscosity lotion and is relatively thin; beauty lotion 2 belongs to a medium-viscosity lotion with an overall medium consistency; beauty lotion 3 belongs to a high-viscosity lotion and presents a cream (paste) state as a whole. The test results show that the molecular probe (HMBDDD) modified based on vanillin provided by the present invention can fully sense the change of the micro-region viscosity (thickness) in the beauty lotion and release it through a visual light signal, which is of great significance for studying the optimal process of different types of beauty lotions.

[0063] Performance test:

[0064] The viscosity response test, photostability test, universality test, and pH stability test were carried out on the molecular probe modified based on vanillin prepared in Example 1.

[0065] (1) Viscosity response test of the molecular probe (HMBDDD) modified based on vanillin

[0066] Prepare a mixed solution containing glycerol and deionized water with different volume fractions. The volume fractions of deionized water and glycerol are shown in Table 1 in detail. Set the external excitation wavelength to 520 nm, control the concentration of the molecular probe modified based on vanillin in the test solution to be 10 μM, and the test is carried out at room temperature. The test results are as Figure 3 shown.

[0067] Table 1 Volume fractions of glycerol and deionized water

[0068] Volume fraction of deionized water Volume fraction of glycerol 100％ 0％ 70％ 30％ 50％ 50％ 30％ 70％ 10％ 90％ 0％ 100％

[0069] At room temperature, the viscosity of deionized water is 1.0 cp, and the viscosity of glycerol reaches 956.0 cp. The viscosity of the mixed solution can be adjusted by adjusting the volume concentration of the two. The specific test results are as Figure 3 shown. As the viscosity of the solution gradually increases, the intensity of the released light signal also gradually increases. In particular, when the volume fraction of glycerol exceeds 50%, the viscosity of the mixed system increases more significantly, and its light signal intensity increases significantly. Compared with the solution system without added glycerol, it increases by up to 16 times at most.

[0070] In addition, it is found that the logarithmic function of the light signal intensity of the mixed solution and the solution viscosity value can be fitted into a straight line, as shown in Figure 4 shown.

[0071] From Figure 4It can be seen that the molecular probe HMBDDD modified with vanillin provided by the present invention can release stronger optical signals as the viscosity value increases. The logarithmic function of the fluorescence signal intensity and the logarithmic function of the viscosity value of the beauty lotion are consistent with -Hoffmann relation. The viscosity sensitivity coefficient of HMBDDD is 0.40, and the fitting determination coefficient is 0.97. The test results show that the molecular probe HMBDDD modified with vanillin provided by the present invention has good detection sensitivity to the micro-region viscosity of the solution and can be used as the supporting data for the viscosity (thickness) blending process of beauty lotions. The specific logarithmic function values are shown in Table 2.

[0072] Table 2 Logarithm of Viscosity and Logarithm of Fluorescence Intensity

[0073] Logarithm of viscosity (logη) 0.01 0.24 0.57 1.03 1.77 2.99 Logarithm of fluorescence intensity (logI) 2.37 2.48 2.75 2.90 3.20 3.58

[0074] 2. Photostability Test of Molecular Probe (HMBDDD) Modified with Vanillin

[0075] Dissolve 2.78 mg of 5-(4-hydroxy-3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxolane-4,6-dione (HMBDDD) prepared in Example 1 in N,N-dimethylformamide (DMF), control its concentration to be 10 mM, and then dilute it to 10 μM during the test, and add it to deionized water and glycerol respectively. Continuously excite it under an excitation light source of 520 nm for 60 min, and test the change rule of its optical signal intensity. The test results are as Figure 5 shown, and the obtained data are shown in Table 3.

[0076] Table 3 Fluorescence Test Results

[0077] Time / min 0 10 20 30 60 Fluorescence intensity in deionized water / a.u. 232.0 227.2 222.1 216.7 213.4 Fluorescence intensity in glycerol / a.u. 3688.2 3680.8 3672.4 3663.5 3650.4

[0078] From Figure 5 the data obtained in Table 3, it can be known that the molecular probe (HMBDDD) modified with vanillin has good photostability, can release stable optical signals under the irradiation of an excitation light source for a long time, and can maintain a high signal release intensity not only in high-viscosity solutions but also in low-viscosity solutions.

[0079] 3. Universality Test of Molecular Probe (HMBDDD) Modified with Vanillin

[0080] Dissolve 1.39 mg of the vanillin-modified molecular probe 5-(4-hydroxy-3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (HMBDDD) of Example 1 in DMF, control its concentration to be 2 mM, and further dilute it to 10 μM during testing. Then add it to 6 common solutions with different polarities respectively to test the variation law of its absorbance. The 6 solutions with different polarities are toluene, dichloromethane, tetrahydrofuran, ethanol, dimethyl sulfoxide, and glycerol. The above tests are carried out at room temperature, and the results are as Figure 6 shown.

[0081] From Figure 6 the obtained results, it can be seen that except for the experimental group of glycerol, the changes in absorbance and absorption wavelength in the remaining 5 common solvents are not significant; in the experimental group of glycerol, the change in its absorbance is not obvious either, but there is a certain degree of red shift. This may be because in the solution atmosphere with higher viscosity, its conformation has spatial conjugation, indirectly extending its conjugation degree. It shows that the vanillin-modified molecular probe (HMBDDD) can effectively absorb the energy of the excitation light in various solutions with different polarities, and the absorption spectrum will not change due to the change of solution polarity, indicating that it has good universality in complex beauty creams and lotions, and the fluctuation of polarity will not affect its measurement effect on viscosity.

[0082] 4. pH stability test of the vanillin-modified molecular probe

[0083] Dissolve 8.34 mg of the vanillin-modified molecular probe 5-(4-hydroxy-3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (HMBDDD) prepared in Example 1 in DMF, control its concentration to be 3 mM, and further dilute it to 10 μM during testing. Then add it to solutions with pH = 3, 5, 6.8, 7.4, 8, and 9 respectively to test the variation law of its absorbance. This test is carried out at room temperature, and the test results are as Figure 7 shown.

[0084] From Figure 7 the obtained test results, it can be seen that the fluorescence intensity of the vanillin-modified molecular probe (HMBDDD) does not change significantly in a relatively wide pH range, and shows good stability of light signal release in this pH range, indicating that the vanillin-modified molecular probe can be used in beauty creams and lotions with various pH atmospheres.

[0085] The molecular probe 5-(4-hydroxy-3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (HMBDDD) modified by vanillin provided by the present invention has a flexible conjugated structure, can exhibit different rotational states in environments with different micro-region viscosities, and can convert the change in micro-region viscosity in beauty creams into an optical signal for presentation, effectively detecting the physical index of micro-region viscosity (thickness) from a brand-new molecular perspective. Various test results show that the molecular probe HMBDDD modified by vanillin can still maintain good optical signal intensity under long-term irradiation, and can still maintain stable optical signals within a wide pH range, with little change in absorbance in solutions with various polarities, making it suitable for complex beauty creams. Its emission wavelength is 604 nm, which can effectively avoid the interference of background optical signals caused by various additives in beauty creams. Moreover, the molecular probe modified by vanillin is prepared by a one-step method, the preparation process is green and environmentally friendly, the final yield is relatively high, the required raw materials are natural products, with low price, simple availability, low preparation cost, and the post-treatment process is simple and easy to operate, overall low-carbon and environmentally friendly, with high cost performance and suitable for industrial application.

[0086] As can be seen from the above embodiments, the present invention provides a molecular probe modified by vanillin, its preparation method and application. The present invention first mixes a dehydrating agent dispersion, a vanillin solution and a Meldrum's acid dispersion in sequence, and then conducts a Knoevenagel condensation reaction to obtain the molecular probe modified by vanillin. The molecular probe modified by vanillin provided by the present invention has stable chemical properties, can still stably exist in complex beauty creams, the signal release is not easily interfered, the sensitivity to viscosity is higher than other factors, and it can maintain good optical stability in solutions with various polarities and various pH values.

[0087] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Application of a vanillin-modified molecular probe in detecting the viscosity of beauty lotion, characterized in that, Just mix the vanillin-modified molecular probe with the beauty lotion, and the mixing concentration of the vanillin-modified molecular probe is 5-15 μmol / L; The molecular probe has the structure shown in Formula I: The vanillin has the structure shown in Formula II:

2. Use of the vanillin-modified molecular probe according to claim 1 in detecting the viscosity of beauty lotion, characterized in that, Mix the dehydrating agent dispersion and the vanillin solution successively with the Meldrum's acid dispersion, and then carry out the Knoevenagel condensation reaction to obtain the vanillin-modified molecular probe.

3. Use of the vanillin-modified molecular probe according to claim 2 in detecting the viscosity of beauty lotion, characterized in that, The dehydrating agent dispersion is composed of a dehydrating agent and a solvent, wherein the dehydrating agent comprises one or more of sodium carbonate, calcium hydroxide, sodium bicarbonate, cesium carbonate, potassium carbonate, potassium bicarbonate, magnesium hydroxide, calcium carbonate, calcium acetate and tin acetate.

4. Use of the vanillin-modified molecular probe according to claim 2 or 3 in detecting the viscosity of beauty lotion, characterized in that, The vanillin solution is composed of vanillin and a solvent; the Meldrum's acid dispersion is composed of Meldrum's acid and a solvent; the solvent independently comprises one or more of tetrahydrofuran, N,N-dimethylformamide, ethyl acetate, ethanol, dimethyl sulfoxide and methanol.

5. Use of the vanillin-modified molecular probe according to claim 4 in detecting the viscosity of beauty lotion, characterized in that, The content of the dehydrating agent in the dehydrating agent dispersion is 1-150 mol / L; the concentration of the vanillin solution is 1-300 mol / L; the content of Meldrum's acid in the Meldrum's acid dispersion is 1-15 mol / L.

6. The application of the vanillin-modified molecular probe according to claim 5 in detecting the viscosity of beauty lotion, characterized in that, The molar ratio of the dehydrating agent, Meldrum's acid and vanillin is 1-150:1:1-20.

7. Use of the vanillin-modified molecular probe according to claim 2 or 5 or 6 in detecting the viscosity of beauty lotion, characterized in that The temperature of the Knoevenagel condensation reaction is 20-100 °C, and the time is 1-96 h.

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