A mechanochromic material containing rhodamine with hydantoin structure and its preparation method and application

Abstract

The present invention belongs to the technical field of mechanochromic materials, and specifically relates to a mechanochromic material containing rhodamine with a hydantoin structure, and its preparation method and application. The rhodamine mechanochromic material containing a hydantoin structure is shown in structure (I), with rhodamine B as the matrix, reduced to rhodamine alcohol, oxidized to generate rhodamine aldehyde, and reacted with hydantoin to prepare a six-membered spirocyclic rhodamine containing a hydantoin structure. The rhodamine compound containing a hydantoin structure involved in the present invention has good ion interference resistance, exhibits photochromic properties in a dichloromethane solvent, and has the properties of mechanical stress discoloration and solvent mixing stress discoloration with high contrast and good repeatability. The solid powder of the rhodamine mechanochromic material containing a hydantoin structure has the characteristic of changing color upon grinding. After the action of mechanical force, the color of the powder changes from yellow to pink, and a reversible color change is achieved during the grinding-heating process.

Description

Technical Field

[0001] The present invention belongs to the technical field of mechanochromic materials, and in particular relates to a mechanochromic material containing rhodamine with a hydantoin structure, and a preparation method and application thereof. Background Art

[0002] Stimuli-responsive functional materials are materials whose structure changes in response to external physical or chemical stimuli, such as light, electricity, force, heat, solvents, and acids and bases, leading to changes in their color and fluorescence. The most common types of stimuli-responsive color-changing materials include photochromics, thermochromics, electrochromics, and mechanochromics. Mechanochromics are smart materials that exhibit a distinct optical signal in response to external forces. Under external forces such as grinding, stretching, and compression, mechanochromics undergo chemical changes in their molecular structure, altering the intermolecular forces. These force-induced changes in the optical signal are often reversible and can be restored to their initial state under certain other stimuli. Furthermore, these changes in the optical signal can be easily observed qualitatively with the naked eye or quantitatively detected using instruments. Therefore, they hold significant application prospects in stress monitoring, material flaw detection, memory chips, anti-counterfeiting printing, and flexible strain sensing. However, the development of mechanochromic materials is limited by a limited variety of materials, unclear color change mechanisms, and difficulties in practical application. Research has shown that molecules with push-pull electronic structures and non-planar structures are highly likely to exhibit mechanochromic properties. Therefore, optimizing molecular structure and designing and synthesizing new mechanochromic materials are of great scientific significance.

[0003] Rhodamine B and its derivatives are well-known molecular switches, exhibiting unique absorption and emission properties through structural isomerization between closed and open ring states upon external stimulation. To date, various stimuli, such as metal ions, acids and bases, and ultraviolet light, have been reported to accelerate the ring-opening reaction of rhodamine lactams. However, rhodamine derivatives exhibiting both mechanochromic and photochromic responses are rare. Therefore, developing novel rhodamine-based mechanochromic materials, establishing efficient new mechanochromic systems, and promoting their practical application are both innovative and challenging, and of great significance. Summary of the Invention

[0004] In view of the current limited variety of mechanochromic materials and their inability to be applied in practice, the purpose of the present invention is to provide a new type of rhodamine mechanochromic material containing a hydantoin structure. This compound has good ionic interference resistance and exhibits photochromic properties in a dichloromethane solvent. It also has mechanical stress discoloration and solvent mixing stress discoloration properties with high contrast and good repeatability. The solid powder of the rhodamine mechanochromic material containing a hydantoin structure has the characteristic of changing color upon grinding. Under the action of mechanical force, the powder color changes from yellow to pink, and a reversible color change is achieved during the grinding-heating process. Due to its excellent mechanochromic properties, it can detect the magnitude of force from a microscopic perspective. It can also be used as an aldose reductase inhibitor, and has important application prospects in the fields of pressure sensing, material flaw detection, and stress detection.

[0005] In order to achieve the above technical objectives and the above technical effects, the technical solution adopted by the present invention is:

[0006] A rhodamine mechanochromic material containing a hydantoin structure has the structural formula shown in (I),

[0007]

[0008] The above-mentioned rhodamine mechanochromic material containing a hydantoin structure and its preparation method include the following steps:

[0009] Rhodamine B is reduced to rhodamine alcohol with LiAlH4, and then oxidized by PCC to obtain rhodamine aldehyde. Weigh a certain amount of hydantoin, add an appropriate amount of ethanolamine to the reaction solution, add the ethanol solution of rhodamine aldehyde to the constant pressure dropping funnel, and then add the solution dropwise to the reaction system. Heat and reflux at 90-100℃ to react. The solution after the reaction is complete is extracted, and the organic solvent is removed by rotary evaporation. Finally, it is purified by column chromatography to prepare a six-membered spirorhodamine mechanochromic material containing a hydantoin structure. The synthetic route is as follows: Figure 1 shown.

[0010] Furthermore, in the above preparation method, the certain amount of hydantoin is added in a molar ratio of 1:1 to rhodamine.

[0011] Furthermore, in the above preparation method, the amount of ethanolamine added is 150-200 μL.

[0012] Furthermore, in the above preparation method, the heating reflux reaction time is 2-3 hours.

[0013] Furthermore, in the above preparation method, the ratio of the column chromatography purification developing solvent is dichloromethane:methanol=20-30:1.

[0014] The above-mentioned class of rhodamines containing hydantoin structures have properties as mechanochromic materials.

[0015] Furthermore, the above properties include good ion interference resistance, photochromic properties in dichloromethane solvent, and mechanical stress color change and solvent mixing stress color change properties with high contrast and good repeatability.

[0016] Furthermore, the above properties include the solid powder having the characteristic of changing color upon grinding. Under the action of mechanical force, the color of the powder changes from yellow to pink, and a reversible color change is achieved during the grinding-heating process.

[0017] The above-mentioned type of rhodamine containing hydantoin structure is used as a mechanochromic material.

[0018] Furthermore, in the above application, the rhodamine mechanochromic material containing a hydantoin structure can detect the magnitude of force from a microscopic perspective, and can also be used as an aldose reductase inhibitor in applications such as pressure sensing, material flaw detection, and stress detection.

[0019] The beneficial effects of the present invention are:

[0020] 1. The rhodamine derivative containing a hydantoin structure provided by the present invention has good ionic interference resistance, is very stable in a moderately alkaline environment, exhibits photochromic properties in a dichloromethane solvent, and has high contrast and good repeatability in mechanical stress color change and solvent mixing stress color change properties.

[0021] 2. The solid powder of the rhodamine mechanochromic material containing a hydantoin structure provided by the present invention has the characteristic of changing color upon grinding. Under the action of mechanical force, the color of the powder changes from yellow to pink, and a reversible color change is achieved during the grinding-heating process.

[0022] 3. The rhodamine mechanochromic material containing a hydantoin structure provided by the present invention can detect the magnitude of force from a microscopic perspective and can also be used as an aldose reductase inhibitor. It has important application prospects in the fields of pressure sensing, material flaw detection, stress detection, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a reaction diagram for the preparation and synthesis of rhodamine mechanochromic materials containing hydantoin structures;

[0024] Figure 2: These are pH titration test spectra of rhodamine solutions containing a hydantoin structure, wherein a is the UV-visible absorption spectra of rhodamine containing a hydantoin structure in an acetonitrile-HEPES = 4:6 system at different pH values, b is the fitting curve of the pH absorption response of rhodamine containing a hydantoin structure in an acetonitrile-HEPES = 4:6 system at 565 nm, c is the emission intensity spectra of rhodamine containing a hydantoin structure in an acetonitrile-HEPES = 4:6 system at different pH values, and d is the fitting curve of the pH fluorescence response at 591 nm.

[0025] Figure 3 The figures are metal ion interference test and anion interference test of a rhodamine solution containing a hydantoin structure; wherein a is a UV-visible absorption spectrum of rhodamine containing a hydantoin structure in an acetonitrile-HEPES=4:6 (pH=7.4) system for 10 times the equivalent of metal ions, b is a fluorescence emission spectrum of rhodamine containing a hydantoin structure in an acetonitrile-HEPES=4:6 (pH=7.4) system for 10 times the equivalent of metal ions, c is a UV-visible absorption spectrum of rhodamine containing a hydantoin structure in an acetonitrile-HEPES=4:6 (pH=7.4) system for 10 times the equivalent of anions, and d is a fluorescence emission spectrum of rhodamine containing a hydantoin structure in an acetonitrile-HEPES=4:6 (pH=7.4) system for 10 times the equivalent of anions;

[0026] Figure 4 This is a photochromic test spectrum of rhodamine containing a hydantoin structure in pure dichloromethane solvent; a is the spectrum change of absorbance with prolonged illumination time, and b is the spectrum change of fluorescence intensity with prolonged illumination time;

[0027] Figure 5 It is the color change phenomenon of rhodamine containing hydantoin structure during the mixing process of acetonitrile and water;

[0028] Figure 6 This is the interface visualization phenomenon of rhodamine containing hydantoin structure in the THF-H2O mutual dissolution process; b is a schematic diagram of interface visualization during the THF-H2O mutual dissolution process, a is a physical picture of interface visualization during the THF-H2O mutual dissolution process, and c is a physical picture of interface visualization under fluorescence during the THF-H2O mutual dissolution process;

[0029] Figure 7 The UV (a) and fluorescence (b) spectra of rhodamine containing hydantoin structure at the interface during THF-H2O dissolution;

[0030] Figure 8 This is the color change phenomenon of rhodamine containing hydantoin structure mixed with potassium chloride (a) and silica gel powder (b) and then ground;

[0031] Figure 9 These are fluorescence images of PMMA-doped rhodamine containing a hydantoin structure in film cracks. (a) is the bright-field image, (b) the red channel image, and (c) the green channel image. DETAILED DESCRIPTION

[0032] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] Example 1 Preparation and Synthesis Method of a Rhodamine Mechanochromic Material Containing a Hydantoin Structure

[0034] A rhodamine mechanochromic material containing a hydantoin structure, the chemical structure of the material is as follows:

[0035]

[0036] The preparation reaction formula of the above-mentioned rhodamine mechanochromic material containing hydantoin structure is as follows:

[0037]

[0038] The preparation method of the rhodamine mechanochromic material containing a hydantoin structure comprises the following steps:

[0039] Weigh 0.3000g of rhodamine B, reduce it to rhodamine alcohol with LiAlH4, and then oxidize it with PCC (pyridinium chlorochromate) to obtain rhodamine aldehyde. Weigh 0.098g of hydantoin in a three-necked flask, add 20mL of ethanol aqueous solution, heat to 40℃ for reaction, prepare 5mL of ethanol solution containing 1% ethanolamine, wait for the hydantoin to dissolve, add 200μL of ethanolamine dissolved in ethanol to obtain a reaction system, and add a 3×10 -4 A 1.5 mol / L ethanol solution of rhodamine aldehyde was added dropwise to the reaction system, and the mixture was heated under reflux at 90°C for 2 hours. The reaction mixture was extracted, and the organic solvent was removed using a rotary evaporator. Finally, column chromatography was performed using a developing solvent consisting of dichloromethane:methanol = 20:1 to obtain a pale yellow solid powder with a yield of 72%. This is a six-membered spirorhodamine mechanochromic material containing a hydantoin structure.

[0040] Example 2 Properties of a Rhodamine Mechanochromic Material Containing a Hydantoin Structure

[0041] (1) pH titration test. A 4:6 acetonitrile-HEPES buffer solution was added to a dichloromethane solution of rhodamine containing a hydantoin structure and mixed well to prepare a solution with a concentration of 2×10 -5mol / L test solution. Adjust the pH of the test solution with dilute hydrochloric acid and sodium hydroxide solutions respectively, test the absorption and fluorescence spectra of rhodamine solution containing hydantoin structure at pH = 2-12, select the maximum absorption value and fluorescence intensity for different pH values, such as Figure 2 Shown are: a) and c) UV-visible absorption and emission intensity spectra of rhodamine containing a hydantoin structure at different pH values ​​in a 4:6 acetonitrile-HEPES solution; b) the fitting curve of the pH absorption response of rhodamine containing a hydantoin structure at 565 nm, and d) the fitting curve of the pH fluorescence response of rhodamine containing a hydantoin structure in a 4:6 acetonitrile-HEPES solution at 591 nm. The pKa (Abs) and pKa (Int) values ​​of the rhodamine containing a hydantoin structure were 4.94±0.01 and 5.96±9.31, respectively. These results indicate that rhodamine compounds containing a hydantoin structure are stable in moderately alkaline conditions.

[0042] (2) Metal ion and anion interference test: A 4:6 acetonitrile-HEPES buffer solution was added to a dichloromethane solution of rhodamine containing a hydantoin structure, and the pH was adjusted to 7.4 with a dilute sodium hydroxide solution. The mixture was mixed to obtain a concentration of 2×10 -5 mol / L of the test solution. Add 10 times the equivalent of metal ion solution and anion solution respectively to obtain UV and fluorescence spectra, such as Figure 3 a and b are rhodamine containing hydantoin structure in acetonitrile-HEPES=4:6 (pH=7.4) system, 30 μL of 2×10 -2 mol / L of Na + , K + Mg 2+ , Ca 2+ 、Fe 2+ 、Fe 3+ 、Mn 2+ 、Zn 2+ , Pb 2+ 、Cd 2+ Cr 3+ 、Ag + 、Hg 2+ 、Cu 2+ 、Al 3+ Metal ion aqueous solution, the obtained UV-visible absorption spectrum and fluorescence emission spectrum. c and d are rhodamine containing hydantoin structure in acetonitrile-HEPES=4:6 (pH=7.4) system, 30μL of 2×10 -2 mol / L HPO4 2- 、H2PO4 - 、F - 、S 2- , ClO - , I- 、CO3 2- 、SO4 2- 、NO3 - 、Cl - The UV-visible absorption and fluorescence emission spectra of the anionic aqueous solution were obtained. The results show that rhodamine compounds containing hydantoin structures are not interfered with by common metal ions and anions, making them more suitable for applications in complex environments.

[0043] (3) Photochromic property test. The concentration is 5×10 -5 The test solution is a pure dichloromethane system with a concentration of 1 mol / L. Irradiate the test solution with 313 nm ultraviolet light. As the illumination time increases, scan the ultraviolet and fluorescence spectra at different illumination times, such as Figure 4 Figures (a) and (b) show the spectral changes in absorbance as a function of illumination time from 0 to 70 minutes, and (c) the spectral changes in fluorescence intensity as a function of illumination time from 0 to 70 minutes. The results demonstrate that, in dichloromethane as the solvent, rhodamine compounds containing a hydantoin structure exhibit photochromic properties, with their absorbance and fluorescence intensity increasing with prolonged illumination.

[0044] (4) Solvent mixing color change test. Rhodamine containing hydantoin structure was dissolved in acetonitrile and added dropwise to water. The final concentration of rhodamine containing hydantoin structure in the system was 5×10 -5 mol / L, the color change phenomenon of rhodamine containing hydantoin structure in the process of mixing acetonitrile and water is shown in the following figure. Figure 5 As shown, the solution gradually turns pink, and then as time goes by, the color of the solution slowly becomes lighter until it reaches the initial solution state.

[0045] (5) Visualization test of the interface of THF-H2O miscibility process. Rhodamine containing hydantoin structure was dissolved in tetrahydrofuran and slowly added dropwise to water. The final concentration of rhodamine containing hydantoin structure in the system was 5×10 -5 mol / L, the results are as follows Figure 6 As shown, the interface between the two solvents is pink and accompanied by red fluorescence. The spectrum of the liquid interface was scanned, and the UV and fluorescence spectra of the liquid interface were as follows: Figure 7 When rhodamine containing a hydantoin structure dissolved in tetrahydrofuran is slowly added to water, stratification occurs and the two solvents gradually dissolve at their interface. The molecular forces during this dissolution process cause the rhodamine containing a hydantoin structure to undergo ring-opening, resulting in red fluorescence with absorption and emission peaks at 567nm and 582nm, respectively.

[0046] (5) Mechanical grinding test. Rhodamine containing hydantoin structure was mixed with potassium chloride and silica gel powder and then ground. The weight ratio of rhodamine containing hydantoin structure: potassium chloride / silica gel powder was 1:20. The results were as follows: Figure 8 Figures (a) and (b) show the color change of rhodamine containing a hydantoin structure before and after grinding after mixing with KCl. After grinding, the solid powder changes from white to light pink. The color of the solid powder gradually fades over time, and the fading process can also be accelerated by heating. Figures (b) show the color change of rhodamine containing a hydantoin structure before and after grinding after mixing with silica gel powder. After grinding, the solid powder changes from white to pink. The color of the solid powder gradually fades over time, and the fading process can also be accelerated by heating.

[0047] Example 3 Application of a rhodamine mechanochromic material containing a hydantoin structure

[0048] The application of rhodamine mechanochromic materials containing hydantoin structure as molecular force response and visualization of different solvent miscibility is as follows: First, a tetrahydrofuran system is prepared with a concentration of 2×10 -4 mol / L of rhodamine containing hydantoin structure, the concentration of 2×10 -4 A 1.5 mol / L tetrahydrofuran test solution is slowly added dropwise to water. During the mutual dissolution of the two solvents, molecular forces cause a visible color change at the interface between the two liquid surfaces. The rhodamine containing a hydantoin structure at the interface changes from yellow, non-fluorescent to pink, red fluorescent. This color change of rhodamine containing a hydantoin structure during the solvent miscibility process can indicate the intermolecular forces involved in the solvent miscibility process, enabling microscopic force testing.

[0049] (1) Based on the color development phenomenon of rhodamine containing hydantoin structure in the process of solvent miscibility, the intermolecular forces in the process of solvent miscibility can be indicated and microscopic force detection can be performed.

[0050] (2) Doping PMMA with rhodamine containing hydantoin structure can detect the cracks in the membrane, such as Figure 9 shown.

[0051] (3) Based on the differences in the ring closure and light-controlled ring opening of rhodamine-containing hydantoin structures, it can be used as an inhibitor of aldose reductase.

[0052] (4) Rhodamine mechanochromic materials containing hyalin structures can also be used in pressure sensing, material flaw detection, stress detection and other fields.

[0053] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A rhodamine mechanochromic material containing a hydantoin structure, characterized in that: The rhodamine mechanochromic material containing a hydantoin structure has the structure shown in (I). ， （Ⅰ）。 2. The method for preparing a rhodamine mechanochromic material containing a hydantoin structure according to claim 1, characterized in that: The following steps are involved: Rhodamine B is reduced to rhodamine alcohol with LiAlH4, and then oxidized with PCC to obtain rhodamine aldehyde. An ethanol aqueous solution of hydantoin is prepared, and an appropriate amount of ethanolamine is added to obtain a reaction system. The ethanol solution of rhodamine aldehyde is added dropwise to the reaction system, heated under reflux for reaction, and the completely reacted solution is extracted, the organic solvent is removed, and the mixture is purified to obtain a rhodamine mechanochromic material containing a hydantoin structure.

3. The method for preparing a rhodamine mechanochromic material containing a hydantoin structure according to claim 2, characterized in that: The heating reflux reaction is a heating reflux reaction at 90-100°C.

4. The method for preparing a rhodamine mechanochromic material containing a hydantoin structure according to claim 2, wherein: The heating reflux reaction time is 2-3 h.

5. The method for preparing a rhodamine mechanochromic material containing a hydantoin structure according to claim 2, characterized in that: The purification is column chromatography purification, and the column chromatography purification developing solvent and the ratio are dichloromethane:methanol=20-30:

1.

6. Use of the rhodamine mechanochromic material containing a hydantoin structure according to claim 1 in visualization of mutual solubility in different solvents.

7. The use according to claim 6, characterized in that Prepare tetrahydrofuran system with a concentration of 2×10 -4 mol / L test solution of rhodamine containing a hydantoin structure, the test solution of tetrahydrofuran system is slowly added dropwise into water. During the process of mutual dissolution of the two different solvents, under the action of molecular forces, a visible color change occurs at the junction of the two solvent liquid surfaces. The rhodamine containing a hydantoin structure at the junction changes from yellow and non-fluorescent to pink and red fluorescent.

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