Fluorescent compounds of o-carborane-thianthrene, fluorescent sensing film and preparation method thereof and application for detecting terpene

Abstract

The application discloses a kind of o-carborane-thioxanthene fluorescent compounds, fluorescent sensing film and its preparation method and the application of detecting terpene, belong to fluorescent sensing material technical field.The o-carborane of the present application is connected with thioxanthene by covalent bond, and a class of D-A type fluorescent compounds is constructed, wherein thioxanthene is used as electron donor to provide fluorescent emission capacity, and o-carborane is used as electron acceptor to give molecular three-dimensional cage-like stereostructure, which effectively inhibits the quenching effect caused by aggregation, so that the material keeps high fluorescence quantum yield in solid state.The fluorescent compound is loaded on the surface of matrix to prepare fluorescent sensing film, and the film has fluorescent response to a variety of terpene volatile organic compounds such as alpha-pinene, beta-pinene, limonene, 3-carene and camphene, wherein the response to alpha-pinene is the most sensitive, has the advantages of fast response speed, good reversibility, excellent cycle stability and the like, and is suitable for forest pest warning, ecological environment monitoring and volatile biomarker detection and other fields.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent sensing materials technology, specifically relating to the design and preparation of a small organic molecule material for a pinene sensor. Based on this material, a fluorescent sensor is built to achieve pinene detection with high sensitivity and fast response speed. Background Technology

[0002] Terpenes are a class of naturally occurring volatile organic compounds (VOCs) widely found in conifers, citrus trees, eucalyptus trees, industrial hemp, and various aromatic plants. They include multiple components such as α-pinene, β-pinene, limonene, myrcene, 3-carene, and terpinene, and possess significant ecological importance and broad application value. Besides their widespread use in fragrances, cosmetics, food additives, pharmaceuticals, and fine chemicals, terpenes are also important chemical signaling molecules for communication between plants and their external environment. When plants are subjected to biotic or abiotic stresses such as pests and diseases, mechanical damage, and drought, the types and concentrations of terpenes they release typically change significantly. Therefore, terpene volatiles can serve as important indicators of plant physiological and health states, enabling rapid, in-situ, and real-time monitoring, which is crucial for plant health diagnosis, precision agriculture management, forest ecological monitoring, and the quality evaluation of agricultural and forestry products.

[0003] Currently, the detection of terpenoid volatile organic compounds mainly relies on analytical methods such as gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). While these methods offer high sensitivity and accuracy, they generally suffer from drawbacks such as cumbersome sample collection and pretreatment procedures, long detection cycles, expensive equipment, and high operational expertise requirements, making them unsuitable for in-situ real-time monitoring applications. To address these challenges, researchers have developed various novel detection technologies, including resistive sensors, quartz crystal microbalance (QCM) sensors, metal-organic framework (MOF) sensors, molecularly imprinted polymer (MIP) sensors, and localized surface plasmon resonance (LSPR) sensors. Although these technologies have made some progress in sensitivity and selectivity, they still generally suffer from problems such as complex preparation of sensitive materials, insufficient batch stability and repeatability, susceptibility to environmental temperature and humidity interference, slow response and recovery speeds, and limited long-term reliability. In particular, some sensors based on adsorption coatings rely on the adsorption, dissolution, and diffusion of terpenoid molecules within the sensitive layer, resulting in long response times and limited detection sensitivity. Therefore, developing a novel terpene volatile organic compound detection technology that combines rapid response, high sensitivity, good selectivity, excellent stability, and easy device integration remains an important technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a fluorescent compound and a fluorescent sensing film that have the function of sensing terpene gases, so as to achieve efficient detection of terpene volatile organic compounds.

[0005] To achieve the above objectives, the present invention provides an ortho-carborane-thiaanthracene fluorescent compound with the following structural formula:

[0006]

[0007] In the formula, R represents any one of -H, -CN, -F, -Cl, -Br, -CF3, -CH3, and -OCH3.

[0008] The preparation method of the above-mentioned ortho-carborane-thiaanthracene fluorescent compounds includes the following steps:

[0009] Step 1: Under nitrogen protection, o-phenylenediol and the o-phenylenedifluoro compound shown in Formula I were added to a mixed solvent of N,N-dimethylformamide and triethylamine, and reacted at 60–80 °C for 8–12 hours. After separation and purification, the compound of Formula II was obtained. The reaction equation is as follows:

[0010]

[0011] Step 2: Under nitrogen protection, compound II, palladium dichloride, cuprous iodide, and phenylacetylene were added to a mixed solvent of triethylamine and tetrahydrofuran. The mixture was reacted at 40–80 °C for 6–8 hours, and then purified to obtain compound III. The reaction equation is as follows:

[0012]

[0013] Step 3: Under nitrogen protection, compound III and decaborane were added to a mixed solvent of toluene and N,N-dimethylaniline, and refluxed at 110-120°C for 8-10 hours. After separation and purification, o-carborane-thiaanthracene fluorescent compounds were obtained.

[0014] Further, in step 1, the molar ratio of the o-phenyl dithiol and the o-phenyl difluoride compound is 1:1.5 to 3, and the volume ratio of the N,N-dimethylformamide and triethylamine is 1:1 to 1.5.

[0015] Further, in step 2, the molar ratio of the compound of formula II, phenylacetylene, palladium dichloride of bis(triphenylphosphine) chloride, and cuprous iodide is 1:2-3:0.1-0.2:0.1-0.15, and the volume ratio of tetrahydrofuran and triethylamine is 1:1.2-1.5.

[0016] Further, in step 3, the molar ratio of the compound of formula III to decaborane is 1:2 to 3, and the volume ratio of toluene to N,N-dimethylaniline is 1:0.01 to 0.02.

[0017] The present invention also provides a fluorescent sensing film comprising the above-mentioned ortho-carborane-thiaanthracene fluorescent compounds.

[0018] The preparation method of the above-mentioned fluorescent sensing film is as follows: o-carborane-thiaanthracene fluorescent compound is added to an organic solvent to prepare a solution with a concentration of 1×10⁻⁶. -4 ~1×10 -3 A mol / L solution of an ortho-carborane-thiane fluorescent compound was uniformly coated onto a substrate, dried, and sealed for storage to obtain a fluorescent sensing film.

[0019] Furthermore, in the above-mentioned method for preparing the fluorescent sensing film, the substrate is glass or filter paper, and the volume of the o-carborane-thiaanthracene fluorescent compound solution coated on the substrate is 40–60 μL / cm³. 2 The organic solvent is any one of dichloromethane, trichloromethane, toluene, and tetrahydrofuran.

[0020] The present invention further provides the application of the above-mentioned fluorescent sensing film in the detection of terpene volatile organic compounds.

[0021] Furthermore, the terpene volatile organic compounds include any one or more of α-pinene, β-pinene, limonene, myrcene, 3-carene, terpinene, and camphene.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention constructs a novel class of DA-type fluorescent compounds by covalently linking o-carborane and thiaanthracene. Thianthracene, acting as an electron donor, provides excellent fluorescence emission, while o-carborane, as an electron acceptor, endows the molecule with a unique three-dimensional cage-like structure. Utilizing the three-dimensional cage-like structure of o-carborane enables spatial distortion and non-planar construction of the molecule, effectively disrupting the tight packing of traditional planar conjugated systems and significantly suppressing excessively strong π-π interactions between molecules, allowing the molecule to maintain a high fluorescence quantum yield in both aggregated and solid states. The thiaanthracene group can be substituted (e.g., by introducing a cyano group), allowing for synergistic regulation of emission wavelength, luminescence efficiency, and volatile organic compound (VOC) response behavior by controlling the molecule's electronic properties, aggregated luminescence behavior, and sensing response performance.

[0024] 2. The method for synthesizing o-carborane-thiaanthracene fluorescent compounds provided by this invention has a clear route, simple operation, readily available raw materials, mild reaction conditions, low equipment requirements, and is suitable for large-scale production.

[0025] 3. Benefiting from the three-dimensional cage-like structure and strong molecular rigidity of o-carborane, combined with the excellent luminescent properties of thiaanthracite, the compound of this invention exhibits high fluorescence quantum yield in both aggregated and solid-state states, breaking through the technical bottleneck of low solid-state luminescence efficiency of traditional organic fluorescent molecules and laying the foundation for its application in solid-state sensor devices. This invention utilizes this fluorescent compound to construct a fluorescent sensing film that selectively responds to terpene volatile organic compounds such as α-pinene, β-pinene, limonene, 3-carene, and camphene. Rapid identification and sensitive detection of plant-derived volatiles are achieved through molecular structure modulation.

[0026] 4. The fluorescent sensing film provided by the present invention can realize fluorescence response to terpene volatile organic compounds, and has a rapid, obvious and reversible fluorescence response to α-pinene. It has a fast response recovery speed and good cycle stability, and can realize sensitive detection of α-pinene gas.

[0027] 5. The method for preparing fluorescent sensing films provided by this invention is simple to operate and has mild reaction conditions. The prepared fluorescent sensing films have good consistency, long service life and good stability, making them an excellent type of terpene gas sensing film material.

[0028] 6. The fluorescent sensing film of this invention enables rapid detection of terpene volatile organic compounds at room temperature. It can be used in conjunction with commercial fluorescent devices to further integrate into a miniaturized, portable gas sensor. This sensor is suitable for applications such as plant volatile matter monitoring, plant health diagnosis, forest pest and disease early warning, ecological environment monitoring, and volatile biomarker detection. It has advantages such as high sensitivity, fast response speed, low cost, ease of large-scale preparation and device integration, and possesses good market application prospects and promotional value. Attached Figure Description

[0029] Figure 1 This is a high-resolution mass spectrum of the fluorescent compound prepared in Example 1.

[0030] Figure 2 This is the 1H NMR spectrum of the fluorescent compound prepared in Example 1.

[0031] Figure 3 This is a high-performance liquid chromatogram of the fluorescent compound prepared in Example 1.

[0032] Figure 4 This is the excitation-emission spectrum of the fluorescent sensing film prepared in Example 5.

[0033] Figure 5 This is a monitoring graph of the photochemical stability of the fluorescent sensing film prepared in Example 5.

[0034] Figure 6 This is a response diagram of the fluorescent sensing film prepared in Example 5 to terpene volatile organic compounds.

[0035] Figure 7 This is the response diagram of the fluorescent sensing film prepared in Example 5 to α-pinene gas sensing.

[0036] Figure 8 This is a gas-phase fluorescence sensing response diagram of the fluorescent sensing film prepared in Example 5 to common interfering substances.

[0037] Figure 9 This is a sensitivity test graph of the fluorescent sensing film prepared in Example 5 to α-pinene gas.

[0038] Figure 10 This is a graph showing the cyclic stability test of the fluorescent sensing film prepared in Example 5 against α-pinene gas. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0040] Example 1

[0041] Step 1: 1 g (7.03 mmol) of o-phenylenediol and 3 g (13.76 mmol) of 4,5-difluoro-2-bromobenzonitrile (Formula I-1) were sequentially added to a 250 mL Shrek flask. The flask was purged with nitrogen three times to remove all air. Then, under nitrogen protection, 50 mL each of ultra-dry N,N-dimethylformamide and ultra-dry triethylamine were added. The reaction system was heated to 80 °C and reacted with stirring for 12 hours. The reaction solution was allowed to cool naturally to room temperature, then poured into 1 L of distilled water. The mixture was extracted multiple times with ethyl acetate, retaining the organic phase, until the organic layer no longer exhibited green fluorescence. The ethyl acetate was removed by rotary evaporation, and the crude product was obtained after drying. Column chromatography was performed using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound of formula II-1. The reaction equation is as follows:

[0042]

[0043] Step 2: Weigh 0.32 g (1 mmol) of compound II-1, 70 mg (0.1 mmol) of palladium dichloride bis(triphenylphosphine) and 18 mg (0.1 mmol) of cuprous iodide into a 100 mL Shrek flask. Purge the apparatus three times with nitrogen to remove air. Under nitrogen protection, add 30 mL of ultra-dry triethylamine and 20 mL of ultra-dry tetrahydrofuran to dissolve the compound. Then, add 0.25 mL (2.5 mmol) of phenylacetylene to the reaction system using a syringe. Heat to 75 °C and reflux with stirring for 8 hours. Afterward, remove the solvent by rotary evaporation. Separate the solution by column chromatography using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound III-1. The reaction equation is as follows:

[0044]

[0045] Step 3: Weigh 100 mg (0.3 mmol) of compound III-1 and 80 mg (0.65 mmol) of decaborane into a 50 mL dry double-necked flask. Add 15 mL of anhydrous toluene and 0.15 mL of N,N-dimethylaniline. Reflux at 120 °C for 10 hours under nitrogen protection. Then cool the reaction solution to room temperature and quench the reaction with 10 mL of methanol. Remove the solvent by rotary evaporation. Separate by column chromatography using a dichloromethane:n-hexane = 1:20 eluent to obtain the target fluorescent compound 2-THCB-CN, which fluoresces orange under 365 nm UV light. The reaction equation is as follows:

[0046]

[0047] The structural characterization data of the obtained fluorescent compound 2-THCB-CN are as follows: Figures 1-3 As shown. Figure 1 The results show that the molecular weight of the synthesized compound is basically consistent with the theoretical value; Figure 2 This indicates that the number of hydrogen atoms in the molecule is consistent with expectations. Figure 3 The image shows the high-performance liquid chromatography (HPLC) chromatogram of 2-THCB-CN, using acetonitrile and tetrahydrofuran as the mobile phase. The sharp single peak in the chromatogram indicates that the obtained product has high purity.

[0048] Example 2

[0049] Step 1: 1 g (7.03 mmol) of o-phenylenediol and 3 g (13.76 mmol) of 3-bromo-4,5-difluorobenzonitrile (Formula I-2) were sequentially added to a 250 mL Shrek flask. The flask was purged with nitrogen three times to remove all air. Then, under nitrogen protection, 50 mL each of ultra-dry N,N-dimethylformamide and ultra-dry triethylamine were added. The reaction system was heated to 80 °C and reacted with stirring for 12 hours. The reaction solution was allowed to cool naturally to room temperature, then poured into 1 L of distilled water. The mixture was extracted multiple times with ethyl acetate, retaining the organic phase, until the organic layer no longer exhibited green fluorescence. The ethyl acetate was removed by rotary evaporation, and the crude product was obtained after drying. Column chromatography was performed using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound of formula II-2. The reaction equation is as follows:

[0050]

[0051] Step 2: Weigh 0.32 g (1 mmol) of compound II-2, 70 mg (0.1 mmol) of palladium dichloride bis(triphenylphosphine) and 18 mg (0.1 mmol) of cuprous iodide into a 100 mL Shrek flask. Purge the apparatus three times with nitrogen to remove air. Under nitrogen protection, add 30 mL of ultra-dry triethylamine and 20 mL of ultra-dry tetrahydrofuran to dissolve the compound. Then, add 0.25 mL (2.5 mmol) of phenylacetylene to the reaction system using a syringe. Heat to 75 °C and reflux with stirring for 8 hours. Afterward, remove the solvent by rotary evaporation. Separate the solution by column chromatography using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound III-2. The reaction equation is as follows:

[0052]

[0053] Step 3: Weigh 100 mg (0.3 mmol) of compound III-2 and 80 mg (0.65 mmol) of decaborane into a 50 mL dry double-necked flask. Add 15 mL of anhydrous toluene and 0.15 mL of N,N-dimethylaniline. Reflux at 120 °C for 10 hours under nitrogen protection. Then cool the reaction solution to room temperature, add 10 mL of methanol to quench the reaction, and then remove the solvent by rotary evaporation. Separate by column chromatography using a dichloromethane:n-hexane = 1:20 system as the eluent to obtain the target fluorescent compound 1-THCB-CN, which fluoresces orange-red under 365 nm UV light. The reaction equation is as follows:

[0054]

[0055] Example 3

[0056] Step 1: 1 g (7.03 mmol) of o-phenylenediol and 3 g (15.5 mmol) of 3,4-difluorobromobenzene (Formula I-3) were sequentially added to a 250 mL Shrek flask. The flask was purged with nitrogen three times to remove all air. Then, under nitrogen protection, 50 mL each of ultra-dry N,N-dimethylformamide and ultra-dry triethylamine were added. The reaction system was heated to 80°C and reacted with stirring for 12 hours. The reaction solution was allowed to cool naturally to room temperature, then poured into 1 L of distilled water. The mixture was extracted multiple times with ethyl acetate, retaining the organic phase, until the organic layer no longer exhibited green fluorescence. The ethyl acetate was removed by rotary evaporation, and the crude product was obtained after drying. Column chromatography was performed using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound of formula II-3. The reaction equation is as follows:

[0057]

[0058] Step 2: Weigh 0.5 g (1.7 mmol) of compound II-3, 120 mg (0.17 mmol) of palladium dichloride bis(triphenylphosphine) and 25 mg (0.17 mmol) of cuprous iodide into a 100 mL Shrek flask. Purge the apparatus three times with nitrogen to remove air. Under nitrogen protection, add 35 mL of ultra-dry triethylamine and 25 mL of ultra-dry tetrahydrofuran to dissolve the compound. Then, add 0.32 mL (3.2 mmol) of phenylacetylene to the reaction system using a syringe. Heat to 75 °C and reflux with stirring for 8 hours. Afterward, remove the solvent by rotary evaporation. Separate the solution by column chromatography using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound III-3. The reaction equation is as follows:

[0059]

[0060] Step 3: Weigh 50 mg (0.16 mmol) of compound III-3 and 40 mg (0.32 mmol) of decaborane into a 50 mL dry double-necked flask. Add 10 mL of anhydrous toluene and 0.15 mL of N,N-dimethylaniline. Reflux at 120 °C for 10 hours under nitrogen protection. Then cool the reaction solution to room temperature, add 10 mL of methanol to quench the reaction, and then remove the solvent by rotary evaporation. Separate by column chromatography using a dichloromethane:n-hexane = 1:20 system as the eluent to obtain the target fluorescent compound 2-THCB, which fluoresces orange under 365 nm UV light. The reaction equation is as follows:

[0061]

[0062] Example 4

[0063] Step 1: 1 g (7.03 mmol) of o-phenylenediol and 3 g (15.5 mmol) of 2,3-difluorobromobenzene (Formula I-4) were sequentially added to a 250 mL Shrek flask. The flask was purged with nitrogen three times to completely remove air. Then, under nitrogen protection, 50 mL each of ultra-dry N,N-dimethylformamide and ultra-dry triethylamine were added. The reaction system was heated to 80°C and reacted with stirring for 12 hours. The reaction solution was allowed to cool naturally to room temperature, then poured into 1 L of distilled water. The mixture was extracted multiple times with ethyl acetate, retaining the organic phase, until the organic layer no longer exhibited green fluorescence. The ethyl acetate was removed by rotary evaporation, and the crude product was obtained after drying. Column chromatography was performed using a dichloromethane:n-hexane = 1:5 eluent to obtain the white compound of formula II-4. The reaction equation is as follows:

[0064]

[0065] Step 2: Weigh 0.5 g (1.58 mmol) of compound II-3, 120 mg (0.16 mmol) of palladium dichloride bis(triphenylphosphine) and 25 mg (0.16 mmol) of cuprous iodide into a 100 mL Shrek flask. Purge the apparatus three times with nitrogen to remove air. Under nitrogen protection, add 35 mL of ultra-dry triethylamine and 25 mL of ultra-dry tetrahydrofuran to dissolve the compound. Then, add 0.32 mL (3.2 mmol) of phenylacetylene to the reaction system using a syringe. Heat to 75 °C and reflux with stirring for 8 hours. Afterward, remove the solvent by rotary evaporation. Separate the solution by column chromatography using a dichloromethane:n-hexane = 1:5 eluent to obtain a white compound III-4. The reaction equation is as follows:

[0066]

[0067] Step 3: Weigh 50 mg (0.16 mmol) of compound III-3 and 40 mg (0.32 mmol) of decaborane into a 50 mL dry double-necked flask. Add 10 mL of anhydrous toluene and 0.15 mL of N,N-dimethylaniline. Reflux at 120 °C for 10 hours under nitrogen protection. Then cool the reaction solution to room temperature and quench the reaction with 10 mL of methanol. Remove the solvent by rotary evaporation. Separate by column chromatography using a dichloromethane:n-hexane = 1:20 eluent to obtain the target fluorescent compound 1-THCB, which fluoresces red under 365 nm UV light. The reaction equation is as follows:

[0068]

[0069] Example 5

[0070] Application of fluorescent compound 2-THCB-CN in fluorescence sensing for detecting terpenoid volatile organic compounds in Example 1

[0071] The fluorescent compound 2-THCB-CN was dissolved in dichloromethane to prepare a solution with a concentration of 1×10⁻⁶. -3 Prepare a 2-THCB-CN stock solution (mol / L). Allow the stock solution to stand to obtain the assembled structure of the fluorescent compound. Seal and store for later use. Coat the stock solution uniformly onto a clean glass plate at a volume of 40–60 μL / cm². 2 The solution was left at room temperature for 1 hour to allow the solvent in the stock solution to evaporate naturally, resulting in a fluorescent sensing film, which was then sealed and stored.

[0072] Various performance tests were conducted on the above-mentioned fluorescent sensing film. The specific experiments and results are as follows:

[0073] 1. Characterization of basic fluorescence behavior

[0074] The excitation and emission spectra of the fluorescent sensing film were characterized using an Edinburgh Instruments FLS 1000 fluorescence spectrometer. The results are shown in the figure. Figure 4 .Depend on Figure 4 It is known that the maximum excitation wavelength of this fluorescent sensing film is 290 nm and the maximum emission wavelength is 650 nm, providing light source and detection wavelength information for the construction of the fluorescent sensor.

[0075] 2. Photochemical and thermodynamic stability testing of fluorescent sensing films

[0076] Photobleaching is one of the key limiting factors for the practical application of fluorescent thin-film sensors. Therefore, the photochemical stability of the film was systematically evaluated before application. The film was continuously irradiated with an excitation source for 10 hours, and the results are as follows: Figure 5 As shown in the figure. The test results show that the fluorescence intensity of the fluorescent sensing film did not decrease significantly under continuous illumination for 10 hours, demonstrating excellent resistance to photobleaching and photochemical stability, which lays a solid foundation for its subsequent stable and repeatable sensing applications.

[0077] 3. Detection test of five terpene gases by fluorescent sensing film

[0078] The saturated vapors of five terpenes—α-pinene, β-pinene, limonene, 3-carene, and camphene—were measured using a fluorescent sensing film. Taking α-pinene as an example, the specific procedure was as follows: α-pinene was encapsulated in a 500 mL reagent bottle and allowed to stand overnight at 20°C and 45% humidity; the fluorescent sensing film was placed in the sensor, and the test was performed at 20°C and 45% humidity; a certain volume of α-pinene gas was drawn from the mouth of the reagent bottle using a microsyringe and injected into a clean gas bag via a 100 mL glass syringe, which was then connected to the sensor inlet. The injection time was approximately 15 seconds, and the injection rate was 200 mL / min. The test was repeated after the sensor recovered. The same procedure was used for the other four terpenes. The test results are as follows: Figure 6 As shown, the fluorescent sensing film exhibits fluorescence responses to five terpenes: α-pinene, β-pinene, limonene, 3-carene, and camphene. The film shows the highest sensitivity and largest quenching amplitude for α-pinene, indicating its effective detection capability, particularly for the rapid identification of α-pinene. Based on this, the fluorescence quenching response of the fluorescent sensing film under 20°C saturated α-pinene vapor was further tested. Figure 7 As shown, the quenching efficiency of saturated α-pinene vapor on the thin film is about 58%, the response time is 9 seconds, the recovery time is about 292 seconds, the sensing process is completely reversible, and the thin film can be restored to its initial state.

[0079] Further testing was conducted to investigate the interference of common coexisting gases in pine forests (such as nitrogen, CO2, O2, H2S, NH3, and water vapor) and common volatile organic compounds (ethanol, toluene, tetrahydrofuran, and methanol) on the fluorescence sensing film's detection of terpene vapor. The results are as follows: Figure 8 As shown in the figure. Experimental results indicate that coexisting gases such as CO2, O2, H2S, and NH3 have virtually no effect on the fluorescence intensity of the film; however, the interference behavior of volatile organic compounds can be divided into two categories: hexane, toluene, dichloromethane, and acetonitrile cause fluorescence quenching, while tetrahydrofuran, methanol, and ethanol cause a certain degree of fluorescence sensitization. This suggests that potential coexisting gases in the environment do not constitute interference, and the film exhibits good selective recognition ability for terpene gases (especially α-pinene), providing an important foundation for its practical application in complex systems such as forest environments.

[0080] 4. Determination of the sensitivity of fluorescent sensing films to α-pinene vapor

[0081] Different concentrations of α-pinene vapor were prepared using the air dilution method, and the response sensitivity of the fluorescent sensing film was tested. The results are shown in [Figure number missing]. Figure 9 .Depend on Figure 9It can be seen that the fluorescence intensity of the film is significantly quenched with the increase of α-pinene vapor concentration. When the α-pinene concentration is 1 ppm, a significant fluorescence quenching signal can still be detected, indicating that the detection limit of the film for α-pinene is less than 1 ppm, and it has high sensitivity.

[0082] 5. Cyclic stability test of fluorescent sensing film in response to α-pinene vapor

[0083] The fluorescent sensing film underwent 100 consecutive α-pinene vapor response cycles, and the results are shown in [Figure number missing]. Figure 10 .Depend on Figure 10 It can be seen that after 100 cycles of testing, the response curve of the thin film is basically consistent with the first measurement, showing excellent recovery and reversibility. The sensing process is completely reversible and has good repeatability, indicating that the thin film has excellent cycle stability and practical application potential.

[0084] In summary, this invention addresses the need for terpene detection by constructing a room-temperature fluorescence sensing system based on o-carborane-thiaanthracene fluorescent compounds. This system fully leverages the synergistic effect of the spatial rigidity of the three-dimensional cage structure of o-carborane and the excellent luminescent properties of thiaanthracene, enabling the material to maintain high luminescence efficiency and good stability even in the solid state. Furthermore, by attaching fluorescent molecules to a glass matrix, the contact probability and area between the analyte gas and the fluorescent molecules are further enhanced, significantly improving the sensing response efficiency.

[0085] Compared with traditional detection techniques, this invention eliminates the need for complex pretreatment and large analytical instruments, enabling rapid and reversible identification and detection of terpene gases, especially α-pinene gases, at room temperature. It offers advantages such as significant response, high sensitivity, stable cycling, and ease of operation. The fluorescent sensing film is simple to prepare, suitable for large-scale production, and exhibits good environmental adaptability and long-term stability. Based on its excellent gas response performance, this material shows promising application prospects in early warning of forest pests and diseases, accurate evaluation of plant volatile organic compounds, and ecological environment monitoring. It also provides new design ideas for the development of novel high-performance fluorescent gas sensing materials.

Claims

1. A 1,000-carborane-thiaanthracene fluorescent compound, characterized in that, The structural formula of the fluorescent compound is shown below: In the formula, R represents any one of -H, -CN, -F, -Cl, -Br, -CF3, -CH3, and -OCH3.

2. A method for preparing the ortho-carborane-thiaanthracene fluorescent compound according to claim 1, characterized in that, The preparation method includes the following steps: Step 1: Under nitrogen protection, o-phenyl dithiol and the o-phenyl difluoro compound shown in Formula I are added to a mixed solvent of N,N-dimethylformamide and triethylamine, and reacted at 60-80°C for 8-12 hours. After separation and purification, the compound of Formula II is obtained. Step 2: Under nitrogen protection, compound II, palladium dichloride, cuprous iodide, and phenylacetylene were added to a mixed solvent of triethylamine and tetrahydrofuran and reacted at 40–80 °C for 6–8 hours. After separation and purification, compound III was obtained. Step 3: Under nitrogen protection, compound III and decaborane were added to a mixed solvent of toluene and N,N-dimethylaniline, and refluxed at 110-120°C for 8-10 hours. After separation and purification, o-carborane-thiaanthracene fluorescent compounds were obtained.

3. The method for preparing the o-carborane-thiaanthracene fluorescent compound according to claim 2, characterized in that, In step 1, the molar ratio of the o-phenyl dithiol and the o-phenyl difluoride compound is 1:1.5 to 3, and the volume ratio of the N,N-dimethylformamide and triethylamine is 1:1 to 1.

5.

4. The method for preparing the o-carborane-thiaanthracene fluorescent compound according to claim 2, characterized in that, In step 2, the molar ratio of the compound of formula II, phenylacetylene, palladium dichloride of bis(triphenylphosphine) chloride, and cuprous iodide is 1:2-3:0.1-0.2:0.1-0.15, and the volume ratio of tetrahydrofuran and triethylamine is 1:1.2-1.

5.

5. The method for preparing the o-carborane-thiaanthracene fluorescent compound according to claim 2, characterized in that, In step 3, the molar ratio of the compound of formula III to decaborane is 1:2 to 3, and the volume ratio of toluene to N,N-dimethylaniline is 1:0.01 to 0.

02.

6. A fluorescent sensing thin film, characterized in that, The fluorescent sensing film comprises the o-carborane-thiaanthracene fluorescent compound as described in claim 1.

7. A method for preparing the fluorescent sensing thin film according to claim 6, characterized in that, An ortho-carborane-thiaanthracene fluorescent compound was added to an organic solvent to prepare a solution with a concentration of 1×10⁻⁶. -4 ~1×10 -3 A mol / L solution of an ortho-carborane-thiathracene fluorescent compound was uniformly coated onto a substrate, dried, and sealed for storage to obtain a fluorescent sensing film.

8. The method for preparing the fluorescent sensing thin film according to claim 7, characterized in that, The substrate is glass or filter paper, and the volume of the o-carborane-thiaanthracene fluorescent compound solution coated on the substrate is 40–60 μL / cm³. 2 The organic solvent is any one of dichloromethane, trichloromethane, toluene, and tetrahydrofuran.

9. The application of the fluorescent sensing film according to claim 6 in the detection of terpene volatile organic compounds.

10. The application of the fluorescent sensing film according to claim 9 in the detection of terpene volatile organic compounds, characterized in that, The terpenoid volatile organic compounds include any one or more of α-pinene, β-pinene, limonene, myrcene, 3-carene, terpinene, and camphene.

Images