Solid-state charge transfer compound and preparation method and application thereof

Abstract

The invention is applicable to the technical field of solid-state charge transfer compounds, and provides a solid-state charge transfer compound and a preparation method and application thereof, the solid-state charge transfer compound is EtLP6 alpha-TFTN, ethyl oblique [6] arene EtLP6 is used as an electron donor, and electron-deficient aromatic tetrafluoroterephthalonitrile is used as an electron acceptor. According to the embodiment of the invention, a solid-state charge transfer (CT) compound formed by ethyl oblique [6] arene (EtLP6) and an electron-deficient aromatic receptor (Tetrafluoro-terephthalonitrile-TFTN) is constructed, and the switching type gasochromic property of the solid-state charge transfer (CT) compound on 1, 3-dioxane and 1, 4-dioxane isomer steam is utilized, so that the solid-state charge transfer (CT) compound can be used for realizing the conversion of 1, 3-dioxane and 1, 4-dioxane isomer steam, and the conversion efficiency of 1, 3-dioxane and 1, 4-dioxane isomer steam is improved. The 2, 4-dioxane isomer can be quickly and visually distinguished and detected; according to the embodiment of the invention, the solid-state charge transfer compound can be obtained through simple mechanical grinding, and a complex solvent crystallization process is not involved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid charge transfer complexes, and in particular relates to a solid charge transfer complex and a preparation method and application thereof. Background Art

[0002] In many fields such as chemical industry, medicine, and pesticides, 1,3-dioxane and 1,4-dioxane have a very wide range of applications due to their unique performance characteristics. However, in actual application, their extremely similar physical and chemical properties bring great difficulties to their rapid and accurate differentiation and detection.

[0003] From the perspective of physical properties, the boiling point, melting point, density and other data of these two compounds are similar, and it is difficult to find obvious differences to effectively distinguish them using conventional physical detection methods; in terms of chemical properties, their activity in chemical reactions and reaction phenomena with various reagents are also very similar, making traditional chemical analysis methods difficult to work.

[0004] At present, the detection of 1,3-dioxane and 1,4-dioxane mainly relies on analytical methods such as gas chromatography and liquid chromatography. Although gas chromatography has high separation efficiency and sensitivity, the sample needs to undergo complex pretreatment, including derivatization and other steps, and the operation process is cumbersome. Liquid chromatography also faces the problem of relatively complex operation, requiring professional technicians to operate, and the detection cycle is long, which cannot meet the needs of rapid detection. In addition, the instruments and equipment are expensive, the maintenance cost is high, and a large amount of reagents and consumables are required, resulting in high overall detection costs. This has greatly limited the widespread application and frequent detection of 1,3-dioxane and 1,4-dioxane in actual production processes. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide a solid charge transfer complex, aiming to solve the problems raised in the above background technology.

[0006] The embodiment of the present invention is implemented as follows: a solid charge transfer complex, wherein the solid charge transfer complex is EtLP6α-TFTN, which uses ethyl ortho[6]arene EtLP6 as an electron donor and electron-deficient aromatic tetrafluoroterephthalonitrile as an electron acceptor.

[0007] Another object of an embodiment of the present invention is to provide a method for preparing a solid charge transfer complex, comprising the following steps: Synthesis of EtLP6; Preparation of solvent-free EtLP6α; EtLP6α and tetrafluoroterephthalonitrile were mixed and ground until the color of the mixture changed from white to light yellow, indicating the formation of a solid charge transfer complex. The molar ratio of EtLP6α to tetrafluoroterephthalonitrile was 1:1.8-2.2.

[0008] Another object of an embodiment of the present invention is to provide an application of a solid-state charge transfer complex in detecting 1,3-dioxane and 1,4-dioxane.

[0009] In the embodiment of the present invention, a solid charge transfer (CT) complex formed by ethyl ortho[6]arene (EtLP6) and an electron-deficient aromatic receptor (tetrafluoroterephthalonitrile - TFTN) is constructed, and its switchable gas-induced color-changing properties for the vapors of 1,3-dioxane and 1,4-dioxane isomers are utilized to achieve rapid and visual differentiation and detection of 1,3-dioxane and 1,4-dioxane isomers; the embodiment of the present invention can obtain the solid charge transfer complex by simple mechanical grinding without involving a complex solvent crystallization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of the preparation process of the solid-state charge transfer complex EtLP6α-TFTN provided in Example 1 of the present invention; Figure 2 Schematic diagram of color change in the gasochromic performance test of EtLP6α-TFTN provided in Example 2 of the present invention; Figure 3 This is the ultraviolet absorption spectrum of EtLP6α-TFTN prepared in Example 1 of the present invention; Figure 4 This is the ultraviolet reflection spectrum of EtLP6α-TFTN prepared in Example 1 of the present invention; Figure 5 This is the PXRD test result of EtLP6α-TFTN prepared in Example 1 of the present invention; Figure 6 This is the H NMR spectrum result of EtLP6α-TFTN prepared in Example 1 of the present invention under 1,4-dioxane vapor stimulation; Figure 7 This is the H NMR spectrum result of EtLP6α-TFTN prepared in Example 1 of the present invention under 1,3-dioxane vapor stimulation; Figure 8 This is the UV absorption spectrum of EtLP6α-TFTN prepared in Example 1 of the present invention under the stimulation of the vapor of two dioxane isomers; Figure 9This is the ultraviolet reflection spectrum of EtLP6α-TFTN prepared in Example 1 of the present invention under the stimulation of vapor of two dioxane isomers; Figure 10 This is the PXRD test result of EtLP6α-TFTN prepared in Example 1 of the present invention under 1,3-dioxane vapor stimulation; Figure 11 This is the PXRD test result of EtLP6α-TFTN prepared in Example 1 of the present invention under 1,4-dioxane vapor stimulation; Figure 12 This is the Raman spectrum of EtLP6α-TFTN prepared in Example 1 of the present invention under the stimulation of vapor of two dioxane isomers; Figure 13 The top view, side view and two-dimensional stacking diagram of the crystal of EtLP6@1,3-dioxane provided in an embodiment of the present invention; Figure 14 The top view, side view and two-dimensional stacking diagram of the crystal of EtLP6@1,4-dioxane provided in an embodiment of the present invention; Figure 15 The top view, side view and two-dimensional stacking diagram of the EtLP6@TFTN crystal provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0012] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0013] Example 1: A solid charge transfer complex EtLP6α-TFTN, the preparation method of which comprises the following steps: 1. Synthesis of EtLP6 material. The synthesis path is as follows:

[0014] 3.5 g of 1,4-dichlorobenzyl (about 20 mmol) and 13.3 g of p-diethoxybenzene (about 80 mmol) were added to a 500 mL round-bottom flask and stirred at room temperature to completely dissolve. 6.0 g of aluminum chloride (about 45 mmol) was added as a catalyst. After the reaction was stopped at room temperature for 2 h, 300 mL of water was added for quenching. After quenching with water, stirring was continued for 2 hours and then stopped. The lower organic phase was separated and extracted using a 500 mL separatory funnel. After extraction three times, 5 g of anhydrous sodium sulfate was added to remove the residual water in the organic phase. 16 g of The silica gel powder was ultrasonically dispersed to obtain a uniform dispersion. The solvent was completely removed by rotary evaporation in a water bath heated at 35°C at a speed of 110 rpm and a vacuum of -12 Pascals to obtain a crude product. The silica gel powder, crude product, anhydrous sodium sulfate, and quartz sand were added to a chromatographic column. A developing solvent consisting of a petroleum ether and ethyl acetate ratio of 6:1 was selected to effectively separate the components on the silica gel plate. The p-diethoxybenzene remaining after the reaction was removed by elution using 2000 mL of a petroleum ether and dichloromethane ratio of 3:1. Subsequently, the EtLP6 intermediate was eluted using 2000 mL of a petroleum ether and dichloromethane ratio of 1:1. The resulting eluent was rotary evaporated to obtain a white solid. After drying in a vacuum oven at 80°C for 12 h, 2.78 g of the EtLP6 intermediate (yield of approximately 32%) was obtained. 2.78 g of EtLP6 intermediate (approximately 6.4 mmol) and 0.6 g of paraformaldehyde (about 20 mmol) were dissolved in 225 mL of dichloromethane and stirred at room temperature to completely dissolve the EtLP6 intermediate. Then, 1 mL of boron trifluoride etherate was added. After reacting at room temperature for 30 minutes, the solution turned dark green and water was added to quench the reaction. 3 g of sodium bicarbonate was added to adjust the pH to neutral and stirring was continued for 1 hour. The lower organic phase was separated and extracted using a 500 mL separatory funnel. After extraction three times, 4 g of anhydrous sodium sulfate was added to remove residual water in the organic phase. 10 g of silica gel powder was added and ultrasonically dispersed to obtain a uniform dispersion. The solvent was completely removed by rotary evaporation under heating at 35°C in a water bath at a speed of 110 rpm and a vacuum of -12 Pascals to obtain a crude product. Silica gel powder, crude product, anhydrous sodium sulfate, and quartz sand were added to fill a chromatographic column. A developing solvent of petroleum ether:ethyl acetate (volume ratio) = 8:1 was selected to separate the components on a silica gel plate. 1000 mL petroleum ether: dichloromethane volume ratio = 1:4 eluent, EtLP6 was eluted, the obtained eluent was subjected to rotary evaporation to obtain a yellow oily substance, 1.5 mL acetone was added and allowed to stand for 2 h to purify it to obtain a white solid, which was dried in a vacuum oven at 120 degrees for 12 hours to obtain 0.972 g EtLP6 (yield of about 34%) (the preparation method of EtLP6 used in the embodiment of the present invention is based on the content of "Wu, J.-R.; Mu, A.; Li, B.; Wang, C.-Y.; Fang, L.; Yang, Y.-W.* Desymmetrized Leaning Pillar[6]arene. Angew. Chem. Int. Ed. 2018, 57, 9853-9858."); 2. Preparation of solvent-free EtLP6α material: Place 0.5 g of EtLP6 in a 20 mL glass bottle, add 8 mL of dichloromethane and heat to 100°C to completely dissolve it. Then, add 8 mL of n-hexane and slowly evaporate it at room temperature for 2 days to obtain block crystals. Wash the liquid attached to the surface with methanol, heat it in a vacuum oven at 120°C for 12 h, and grind it in a mortar to obtain powdered solvent-free EtLP6α. 3. Preparation of solid charge transfer complex EtLP6α-TFTN, such as Figure 1 As shown: 0.223 g of EtLP6 α (0.25 mmol) and 0.1 g of tetrafluoroterephthalonitrile (TFTN) (purchased from Anaiji Chemical, CAS No.: 1835-49-0, Product No.: D040524) (0.5 mmol) were mixed in an agate mortar and pestle. The mixture was thoroughly ground at room temperature using a pestle until the color of the mixture changed significantly. The white EtLP6α and TFTN formed a light yellow mixed powder after grinding, indicating the formation of a solid-state charge transfer complex.

[0015] Example 2: Application of the solid-state charge transfer complex EtLP6α-TFTN material in the detection of 1,3-dioxane and 1,4-dioxane: After adding 2 mL of 1,3-dioxane and 1,4-dioxane to two 20 mL glass bottles, respectively, two 2 mL injection glass bottles containing 10 mg of light yellow EtLP6α-TFTN powder were placed into the two 20 mL glass bottles for gaseous color change performance testing. After 2 hours, obvious color change was observed; After 2 hours, two 2 mL injection glass bottles were taken out from two 20 mL glass bottles, and a small amount of EtLP6α-TFTN powder was taken out with a small spoon and placed on weighing paper. The color change of EtLP6α-TFTN was recorded by taking pictures under the same background and lighting in a small studio, as shown in FIG. Figure 2 As shown; It can be seen that the solid-state charge transfer complex EtLP6α-TFTN exhibits a switch-type gasochromic effect under the stimulation of 1,3-dioxane and 1,4-dioxane isomer vapors, thereby realizing the rapid detection of these two dioxane isomers. Specifically, EtLP6α-TFTN will change from a light yellow powder to a dark yellow powder under the stimulation of 1,3-dioxane vapor; and from a light yellow powder to a white powder under the stimulation of 1,4-dioxane vapor.

[0016] Performance testing: 1. The properties of EtLP6α-TFTN prepared in Example 1 were characterized by measuring the UV absorption spectrum and UV reflection spectrum using a UV-visible spectrophotometer, and performing PXRD tests using a powder diffractometer to analyze whether grinding would cause changes in the crystal phase. The test results are as follows: Figures 3 to 5 As shown, specifically: UV absorption spectroscopy was used to detect changes in characteristic absorption bands caused by CT interaction. When white EtLP6α and TFTN were mixed and ground at a molar ratio of 1:2, a significant color change occurred, resulting in a light yellow mixture powder. Solid-state UV-visible absorption spectroscopy showed that EtLP6α-TFTN had a significant absorption band in the visible light region, which was in sharp contrast to the single-component EtLP6α and TFTN, which had no absorption band in the visible light range ( Figure 3 ); By measuring the change in reflected light intensity with wavelength, the UV reflectance spectrum can be obtained, which can then be used to analyze the characteristics of the material's color change. When white EtLP6α and TFTN are mixed and ground at a 1:2 (molar ratio) to form a pale yellow EtLP6α-TFTN powder, the solid UV reflectance spectrum can clearly reflect this color change. Compared with the single-component EtLP6α and TFTN, which have almost no reflection characteristics in the visible light range, the EtLP6α-TFTN powder shows a significant change in reflection characteristics in the visible light region ( Figure 4 ), which is consistent with the changes in the characteristic absorption bands observed in the UV absorption spectrum, and together reveals the differences in the optical properties of the material in different states; In order to explore the effect of EtLP6α and TFTN mixed grinding on the crystal structure, PXRD test was carried out, and the results are as follows Figure 5 As shown, the PXRD spectrum of EtLP6α-TFTN formed after mixed grinding is compared with the PXRD spectrum of EtLP6α and TFTN physically mixed, only the diffraction peak intensity of EtLP6α and TFTN has changed, and no new crystal phase has been formed.

[0017] 2. For the gas-induced color change experiment of EtLP6α-TFTN prepared in Example 1 under the stimulation of the vapor of two dioxane isomers, the nuclear magnetic resonance hydrogen spectrum was measured using a nuclear magnetic resonance instrument to compare whether the composition of the EtLP6α-TFTN powder before and after the color change was changed. The UV absorption spectrum and UV reflectance spectrum were measured using a UV-visible spectrophotometer. The PXRD test was performed using a powder diffractometer to analyze the changes in the crystal structure of EtLP6α-TFTN before and after the color change. In order to further explore the dynamic changes in the CT interaction between EtLP6α and TFTN under the stimulation of 1,3-dioxane and 1,4-dioxane vapor, Raman spectrometry was performed on the sample using a Raman spectrometer to capture the microscopic information at the molecular vibration level, thereby comprehensively analyzing the changes in the CT interaction between the two. The test results are as follows: Figures 6 to 12 As shown, specifically: The results of H NMR spectroscopy showed that 1,4-dioxane vapor was adsorbed by EtLP6α-TFTN, and the adsorption amount of 1,4-dioxane vapor was calculated to be approximately 3.0 mol / mol EtLP6α-TFTN ( Figure 6 ), while EtLP6α-TFTN does not adsorb 1,3-dioxane vapor ( Figure 7 ); The characteristic absorption band changes caused by CT interaction were analyzed by UV absorption spectroscopy. Figure 8 It can be seen that the absorption peak intensity of EtLP6α-TFTN increased significantly and the peak shift red-shifted under the stimulation of 1,3-dioxane vapor, indicating that the CT interaction was enhanced and the corresponding color deepened; while the absorption peak intensity weakened and the peak shift blue-shifted under the stimulation of 1,4-dioxane vapor, indicating that the CT interaction was weakened and the corresponding color became lighter. These changes clearly show the difference in the characteristic absorption bands before and after the color change, revealing the optical response characteristics of EtLP6α-TFTN under different vapor stimuli; By measuring the change of reflected light intensity with wavelength, the ultraviolet reflection spectrum can be obtained, and then the characteristics of material color change can be analyzed. Figure 9 As can be seen from the figure, the reflectivity of EtLP6α-TFTN decreases overall under the stimulation of 1,3-dioxane vapor, especially in the visible light region, indicating that the color of the material deepens and the CT interaction is enhanced; while under the stimulation of 1,4-dioxane vapor, the reflectivity increases overall, the color becomes lighter, and the CT interaction is weakened. The changes in the UV reflectivity spectrum correspond to the changes in the color of the material and the changes in the CT interaction. In order to explore the changes in the crystal structure of EtLP6α-TFTN before and after color change, PXRD test was carried out, and the results are as follows: Figure 10 、 Figure 11As shown in the figure, the PXRD spectrum of EtLP6α-TFTN@1,3-dioxane, whose color changes to dark yellow under the stimulation of 1,3-dioxane vapor, is different from the PXRD spectrum of the original EtLP6α-TFTN, indicating that the crystal structure of EtLP6α-TFTN changes under the stimulation of 1,3-dioxane vapor, forming a new crystal structure, and the crystal structure of EtLP6@TFTN is obtained by growing crystals. The PXRD pattern of the simulated EtLP6@TFTN (Simulated EtLP6@TFTN) exported by mercury software is roughly the same as the PXRD pattern of EtLP6α-TFTN@1,3-dioxane, whose color changes to dark yellow under the stimulation of 1,3-dioxane vapor, indicating that EtLP6α-TFTN will gradually change into the eutectic of EtLP6@TFTN under the stimulation of 1,4 The PXRD spectrum of EtLP6α-TFTN@1,4-dioxane, which changes to white under the stimulation of 1,4-dioxane vapor, is also different from the PXRD spectrum of the original EtLP6α-TFTN, indicating that the crystal structure of EtLP6α-TFTN has also changed after the adsorption of 1,4-dioxane vapor, forming a new crystal structure. The PXRD pattern of EtLP6α@1,4-dioxane measured after EtLP6α adsorbs 1,4-dioxane is roughly the same as the PXRD pattern of EtLP6α-TFTN@1,4-dioxane, which changes to white after the adsorption of 1,4-dioxane vapor. In addition, the significant TFTN diffraction peak reappears in the PXRD pattern of EtLP6α-TFTN@1,4-dioxane, indicating that the 1,4-dioxane vapor has changed the crystal structure of EtLP6α-TFTN. -The CT interaction between EtLP6α and TFTN is destroyed under the stimulation of dioxane vapor, and EtLP6α-TFTN dissociates. After dissociation, due to the continuous adsorption of 1,4-dioxane by EtLP6α, the crystal structure also changes to EtLP6α@1,4-dioxane; Raman spectroscopy was used to demonstrate the differences between the CT interactions of EtLP6α-TFTN@1,3-dioxane and EtLP6α-TFTN@1,4-dioxane. Figure 12 As shown in the Raman spectrum of EtLP6α-TFTN, the typical absorption peak of the CN group of TFTN (at about 2238 cm -1The peak intensity of the absorption peak at (at) is greatly reduced compared with that of single-component TFTN, which may be due to the strong extra-cavity charge transfer (CT) interaction between EtLP6 and TFTN producing a shielding effect. In the Raman spectrum of EtLP6α-TFTN@1,3-dioxane, the peak intensity of the typical absorption peak of the CN group of TFTN is further reduced compared with that of EtLP6α-TFTN, which indicates that under the vapor stimulation of 1,3-dioxane, the extra-cavity charge transfer (CT) interaction between EtLP6α and TFTN is enhanced, and it transforms to the eutectic of EtLP6-TFTN; on the contrary, the Raman spectrum of EtLP6α-TFTN@1,4-dioxane shows a strong absorption peak related to the CN group similar to that of single-component TFTN, which proves that the adsorption of 1,4-dioxane on EtLP6α-TFTN greatly weakens the CT interaction between EtLP6α-TFTN, thereby greatly weakening the shielding effect.

[0018] 3. Crystal growth and crystal structure analysis of EtLP6@1,3-dioxane: 1.5 mg of EtLP6 was placed in a 2 ml glass vial, and 1 mL of 1,3-dioxane solution was added and heated on a hot plate at 50 °C for 3 minutes to completely dissolve it. The solution was then allowed to evaporate slowly at room temperature. Finally, a smooth, crack-free bulk crystal was obtained. Single crystal XRD analysis of the grown crystals revealed the crystal structure of EtLP6@1,3-dioxane (see Figure 2). Figure 13 As shown in the figure, the crystal structure was analyzed using mercury software and it was found that EtLP6 and 1,3-dioxane were bound in a molar ratio of 1:1, of which 75% of 1,3-dioxane was encapsulated in the cavity formed by EtLP6, and 25% of 1,3-dioxane was bound to EtLP6 in a complexed manner outside the cavity. It was also analyzed that 1,3-dioxane and EtLP6 were bound through multiple weak interactions.

[0019] 4. Crystal growth and crystal structure analysis of EtLP6@1,4-dioxane: 1.5 mg of EtLP6 was placed in a 2 ml glass vial, and 1 mL of 1,4-dioxane solution was added and heated on a hot plate at 50 °C for 3 minutes to completely dissolve it. It was then allowed to evaporate slowly at room temperature. Finally, a smooth, crack-free bulk crystal was obtained. Single crystal XRD analysis of the grown crystals revealed the crystal structure of EtLP6@1,4-dioxane (see Figure 2). Figure 14As shown), using mercury software to analyze the crystal structure, it was found that EtLP6 and 1,4-dioxane are bound in a molar ratio of 1:3, of which 1 / 3 of 1,4-dioxane is encapsulated in the cavity formed by EtLP6, and 2 / 3 of 1,4-dioxane is bound to EtLP6 in a complexed manner outside the cavity. It was also analyzed that 1,4-dioxane and EtLP6 are bound through multiple weak interactions.

[0020] 5. Crystal growth and crystal structure analysis of EtLP6@TFTN: 1.0 mg of EtLP6 and 1.0 mg of TFTN were placed in a 2 ml glass vial, and 1.5 mL of methylcyclohexane solution was added and heated on a hot plate at 60 ° C for 5 minutes to completely dissolve them. The solution was then allowed to evaporate slowly at room temperature, and finally, a smooth, crack-free bulk crystal was obtained. The grown crystal was subjected to single crystal XRD analysis, and the crystal structure of EtLP6@TFTN was obtained (see Figure 2). Figure 15 As shown in the figure, the crystal structure was analyzed using mercury software and it was found that EtLP6 and TFTN were combined in a molar ratio of 1:1. TFTN was located outside the cavity of EtLP6 and was mainly combined through the π-π interaction between the benzene rings. The PXRD pattern of EtLP6@TFTN can be simulated using mercury software.

[0021] 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 and improvements 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 solid charge transfer complex, characterized in that The solid charge transfer complex is EtLP6α-TFTN, which uses ethyl ortho[6]arene EtLP6 as an electron donor and electron-deficient aromatic tetrafluoroterephthalonitrile as an electron acceptor.

2. A method for preparing a solid charge transfer complex according to claim 1, characterized in that: The following steps are involved: Synthesis of EtLP6; Preparation of solvent-free EtLP6α; EtLP6α and tetrafluoroterephthalonitrile were mixed and ground until the color of the mixture changed from white to light yellow, indicating the formation of a solid charge transfer complex. The molar ratio of EtLP6α to tetrafluoroterephthalonitrile was 1:1.8-2.

2.

3. The method for preparing a solid charge transfer complex according to claim 2, wherein: The steps of synthesizing EtLP6 specifically include: 1,4-dichlorobenzyl, p-diethoxybenzene, and dichloromethane were stirred at room temperature until completely dissolved, aluminum chloride was added, reacted at room temperature, quenched with water, and stirred continuously. The lower organic phase was extracted, and the water was removed. Silica gel powder was added and ultrasonically dispersed, heated in a water bath, and rotary evaporated to obtain a crude product, which was then separated using a chromatographic column, eluted, rotary evaporated, and dried to obtain the EtLP6 intermediate. The EtLP6 intermediate and paraformaldehyde were dissolved in dichloromethane and stirred at room temperature to completely dissolve the EtLP6 intermediate. Boron trifluoride etherate was then added and reacted at room temperature until the solution turned dark green. Water was then added to quench the reaction. The pH was adjusted to neutral and stirring was continued. The lower organic phase was extracted and the water was removed. Silica gel powder was added and ultrasonically dispersed to obtain a uniform dispersion. The product was heated in a water bath and rotary evaporated to obtain a crude product. The crude product was then separated, eluted, rotary evaporated, purified, and dried using a chromatographic column to obtain EtLP6.

4. The method for preparing a solid charge transfer complex according to claim 2, wherein: The steps of preparing solvent-free EtLP6α specifically include: Dichloromethane was added to EtLP6 and heated to completely dissolve it. N-hexane was added and evaporated at room temperature to obtain block crystals. The liquid attached to the surface was washed with methanol, and the crystals were dried and ground to obtain powdered solvent-free EtLP6α.

5. The method for preparing a solid charge transfer complex according to claim 2, wherein: The molar ratio of EtLP6α to tetrafluoroterephthalonitrile is 1:

2.

6. Use of the solid-state charge transfer complex according to claim 1 in detecting 1,3-dioxane and 1,4-dioxane.

7. The use according to claim 6, characterized in that The solid charge transfer complex changes from a light yellow powder to a dark yellow powder under the stimulation of 1,3-dioxane vapor; The solid charge transfer complex changes from light yellow powder to white powder under the stimulation of 1,4-dioxane vapor.

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