Fluorescence sensing material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of fluorescent materials, and particularly discloses a fluorescent sensing material as well as a preparation method and application thereof. The fluorescent sensing material is a carborane-containing boron-oxygen multiple resonance fluorescent derivative, boron-oxygen multiple resonance molecules are combined with ortho-carborane, so that the fluorescent sensing material has a unique structure, and the structure can effectively capture BTEX gas molecules, so that the fluorescent sensing material is subjected to fluorescence quenching; therefore, efficient detection of the BTEX gas is realized. The boron-oxygen multi-resonance fluorescent sensing material containing carborane prepared by the invention can realize specific detection on BTEX steam, and shows excellent properties such as high response speed, short recovery time, low detection limit, recoverable utilization and large Stokes shift. By utilizing the method, the problems of expensive detection equipment, complicated operation and low detection sensitivity of the existing BTEX gas detection method are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of fluorescent materials, and specifically discloses a fluorescent sensing material, a preparation method and an application thereof. Background Art

[0002] The booming industrial and agricultural sectors are leading to a growing emission of volatile organic compounds (VOCs) into indoor and outdoor air. BTEX, a mixture of benzene, toluene, ethylbenzene, and xylene, is generated from a wide range of sources, including fuel storage, vehicle emissions, and paint application. BTEX is highly volatile, toxic, and carcinogenic, posing a serious threat to human health. Studies have shown that the maximum concentration limit for human exposure to benzene over an eight-hour period is 0.1 ppm, while that for toluene, ethylbenzene, and xylene is 100 ppm. Therefore, developing technology that can accurately detect trace amounts of BTEX is crucial for protecting human health.

[0003] Currently, BTEX gas is commonly analyzed using gas chromatography coupled with various detectors. However, this method requires expensive equipment, is cumbersome to operate, and is time-consuming, making rapid on-site detection difficult. In recent years, a variety of sensors have emerged, such as metal oxide semiconductor (MOS) sensors and field-effect transistor (FET) sensors. However, these sensors suffer from design limitations, high energy consumption, and low sensitivity. In contrast, fluorescent thin-film sensors offer significant potential for detection due to their miniaturization, high sensitivity, rapid response, reusability, ease of operation, and low power consumption. Therefore, developing a novel fluorescent thin-film sensor for BTEX gas detection is of great practical significance. Summary of the Invention

[0004] To address the challenges of existing BTEX gas detection methods, which suffer from expensive equipment, an inability to perform in-situ detection, cumbersome operation, high energy consumption, and low sensitivity, the present invention provides a fluorescent sensing material, its preparation method, and its application. This fluorescent sensing material is a boron-oxygen multiple resonance fluorescence derivative containing carborane. By combining boron-oxygen multiple resonance molecules with ortho-carborane, the fluorescent sensing material possesses a unique structure that effectively captures BTEX gas molecules, resulting in fluorescence quenching within the fluorescent sensing material. This enables efficient BTEX gas detection, addressing the shortcomings of existing technologies.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The first aspect of the present invention provides a fluorescent sensing material, the structural formula of the fluorescent sensing material is shown in Formula 1:

[0006] Formula 1 Wherein, R1 and R2 can be independently selected from -H, -X (X is any one of F, Cl, Br or I), C1-C 10 Alkyl, C1-C 10 Cycloalkyl, C1-C 10 Alkoxy, C6-C 60 Aromatic ring or C3-C 60 Any one of the aromatic heterocyclic groups and their derivatives.

[0007] Compared to existing technologies, the present invention designs a carborane-containing boron-oxygen multi-resonance fluorescence sensing material. This fluorescent sensing material's structure is designed to capture BTEX molecules. When BTEX gas contacts the surface of a film prepared using this fluorescent sensing material, a solvation effect occurs, leading to fluorescence quenching, thereby enabling fluorescent detection of BTEX molecules. In particular, the introduction of decaborane imparts aggregation-induced emission properties to the fluorescent sensing material, improving its fluorescence quantum yield in both the solid-state and thin-film states. Furthermore, this fluorescent sensing material possesses a relatively loose structure in the solid state, forming abundant molecular channels upon accumulation. This improves the mass transfer efficiency of the fluorescent sensor for BTEX vapor, thereby enhancing the sensor's sensitivity to BTEX vapor detection.

[0008] The carborane-containing boron-oxygen multiple resonance fluorescence sensing material prepared by the present invention can realize specific detection of BTEX vapor, and exhibits excellent properties such as fast response speed, short recovery time, low detection limit, recoverable utilization and large Stokes shift, which solves the problems of high energy consumption, high detection cost, complex operation and inability to detect in situ in existing detection methods.

[0009] Preferably, R1 and R2 can be independently selected from any one of -H, -X (X is any one of F, Cl, Br or I), -CH3, -CH2CH3, -CH(CH3)2, -CH(CH3)CH2CH3, -CH2C(CH3)3, -CH2(CH2)5CH3, cyclopropyl, tert-butyl, cyclobutyl, cyclopentyl or cyclohexyl.

[0010] A second aspect of the present invention provides a method for preparing the fluorescent sensing material, comprising the following steps: Step 1: In an inert atmosphere, 2,5-dibromo-1,3-difluorobenzene, basic salt and R-Ar-OH are mixed uniformly, dissolved in an organic solvent, and reacted at 100-110°C to obtain intermediate 1; Step 2: Dissolve the intermediate 1 in an aromatic solvent in an inert atmosphere, add n-butyl lithium, boron tribromide and a neutralizing stabilizer in sequence, mix well, and heat under reflux to obtain intermediate 2; Step 3: In an inert atmosphere, the intermediate 2, p-cyanophenylacetylene and an organic catalyst are uniformly mixed and dissolved in a mixed organic amine solvent, and a coupling reaction is carried out at 110-115° C. to obtain intermediate 3; Step 4: In an inert atmosphere, decaborane and an activator are mixed evenly, dissolved in a phenyl solvent, and activated at 110-115° C., cooled to obtain an activated reaction solution; the intermediate 3 is added to the activated reaction solution to carry out an alkyne-hydrogen addition reaction to obtain a fluorescent sensing material.

[0011] The present invention also discloses a method for preparing a carborane-containing borane-oxygen multiple resonance fluorescence derivative, wherein the target product is obtained through a substitution reaction, an addition reaction, a Sonogashira coupling reaction, and an alkyne-hydrogen addition method. In the Sonogashira coupling reaction, Pd / Cu is used as a catalyst and an amine is used as a solvent to combine the borane-oxygen multiple resonance mother nucleus with an alkynyl hydrocarbon to obtain an intermediate 3. The intermediate 3, a compound containing a target functional group and a triple bond, is then reacted with decaborane using the alkyne-hydrogen addition method to introduce decaborane into the molecular structure, thereby obtaining the target product.

[0012] Preferably, in step 1, the basic salt is cesium carbonate.

[0013] Preferably, in step 1, the organic solvent is N-methylpyrrolidone.

[0014] Preferably, in step 1, the molar ratio of 2,5-dibromo-1,3-difluorobenzene, basic salt and R-Ar-OH is 1:2.5:2.2-1:2.5:2.5.

[0015] Preferably, in step 1, the mass volume ratio of the total mass of the 2,5-dibromo-1,3-difluorobenzene, the basic salt and R-Ar-OH to the organic solvent is 1 g:3 mL to 1 g:4 mL.

[0016] Preferably, in step 1, the reaction time is 36-48 hours.

[0017] Preferably, step one also includes column chromatography separation.

[0018] Further preferably, in step 1, the eluent for column chromatography separation is n-hexane.

[0019] Preferably, step one also includes a drying operation.

[0020] Further preferably, in step 1, the drying temperature is 100-120° C., and the drying time is 6-10 h.

[0021] Preferably, in step 2, the aromatic solvent is m-xylene.

[0022] Preferably, in step 2, the neutralizing stabilizer is N,N-diisopropylethylamine.

[0023] Preferably, in step 2, the molar ratio of the intermediate 1, n-butyl lithium, boron tribromide and neutralizing stabilizer is 1:1.05:1.2:2.07-1:1.06:1.24:2.07.

[0024] Preferably, in step 2, the mass volume ratio of the intermediate 1 to the aromatic solvent is 1 g:10 mL-1 g:15 mL.

[0025] Preferably, in step 2, the reflux time is 12-24 hours.

[0026] Preferably, step 2 further includes column chromatography separation.

[0027] Further preferably, in step 2, the eluent for column chromatography separation is n-hexane.

[0028] Preferably, in step 3, the organic catalyst is Pd(PPh3)2Cl2 and CuI in a molar ratio of 0.05:0.01-0.05:0.02.

[0029] Preferably, in step three, the mixed organic amine solvent is toluene and triethylamine in a volume ratio of 1:1-4:1.

[0030] Preferably, in step 3, the mass-to-volume ratio of the total mass of the intermediate 2, p-cyanophenylacetylene and the organic catalyst to the mixed organic amine solvent is 1 g:25 mL-1 g:50 mL.

[0031] Preferably, in step 3, the coupling reaction time is 12-24 hours.

[0032] Further preferably, in step three, the molar ratio of the intermediate 2, p-cyanophenylacetylene and Pd(PPh3)2Cl2 in the organic catalyst is 1:4:0.05-1:4:0.1.

[0033] Preferably, step three also includes column chromatography separation.

[0034] Further preferably, in step three, the eluent for column chromatography separation is dichloromethane and n-hexane in a volume ratio of 1:10-1:20.

[0035] More preferably, in step three, the eluent for column chromatography separation is dichloromethane and n-hexane in a volume ratio of 1:10.

[0036] Preferably, in step 4, the activating agent is N,N-dimethylaniline.

[0037] Preferably, in step 4, the activation reaction time is 2-3 hours.

[0038] Preferably, in step 4, the molar ratio of decaborane, activator and intermediate 3 is 1:1.1:0.33-1:1.17:0.33.

[0039] Preferably, in step 4, the mass volume ratio of the total mass of the decaborane and the activator to the phenyl solvent is 1 g:15 mL-1 g:25 mL.

[0040] Preferably, in step 4, the reaction temperature of the alkyne-hydrogen addition reaction is 110-115° C., and the time of the alkyne-hydrogen addition reaction is 12-24 h.

[0041] Preferably, step four also includes column chromatography separation.

[0042] Further preferably, in step 4, the eluent for column chromatography separation is dichloromethane and n-hexane in a volume ratio of 1:5-1:7.

[0043] More preferably, in step 4, the eluent for column chromatography separation is dichloromethane and n-hexane in a volume ratio of 1:5.

[0044] A third aspect of the present invention provides a fluorescent thin film sensor made using the fluorescent sensing material.

[0045] A fourth aspect of the present invention provides a method for preparing a fluorescent thin film sensor, comprising the following steps: Step 1: dissolving the fluorescent sensing material in an organic solvent to obtain a mother solution; Step 2: dissolving sodium carboxymethyl cellulose in deionized water, stirring evenly, adding silica gel powder, mixing evenly to obtain a silica gel solution; applying the silica gel solution evenly on the substrate, and drying to obtain a pretreated substrate; Step 3: coating the mother solution on the pretreated substrate and drying to obtain a fluorescent thin film sensor.

[0046] Preferably, in step 1, the organic solvent is any one of toluene, tetrahydrofuran or chloroform.

[0047] Preferably, in step 2, the substrate is a quartz sheet or a polyurethane sheet.

[0048] A fifth aspect of the present invention provides an application of the fluorescent thin film sensor in detecting BTEX gas.

[0049] In summary, the fluorescent thin-film sensor fabricated using the carborane-containing boron-oxygen multiple resonance fluorescence sensing material prepared in this invention exhibits excellent stability and repeatability, high sensitivity, and good selectivity for detecting BTEX vapor. It is virtually unaffected by water vapor, exhibits a fast response speed, and has a short recovery time. Increasing the pump speed further shortens this recovery time, and BTEX vapors can be distinguished based on their different recovery times. This invention enables real-time, online, in-situ detection of BTEX vapor and has broad application prospects in industrial environmental monitoring, air quality assessment, and volatile organic compound analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is the H NMR spectrum of the fluorescent sensing material BO-CB-CN obtained in Example 1 of the present invention; Figure 2 This is the NMR carbon spectrum of the fluorescent sensing material BO-CB-CN obtained in Example 1 of the present invention; Figure 3 This is a high-resolution mass spectrum of the fluorescent sensing material BO-CB-CN obtained in Example 1 of the present invention; Figure 4 The UV-visible absorption and fluorescence emission spectra of the fluorescent sensing material BO-CB-CN obtained in Example 1 of the present invention are shown; Figure 5 This is a photochemical stability spectrum of the fluorescent film prepared using the fluorescent sensing material BO-CB-CN obtained in Example 1 of the present invention; Figure 6 This is the selectivity spectrum of the fluorescent film prepared using the fluorescent sensing material BO-CB-CN obtained in Example 1 to BTEX vapor; Figure 7 The detection limit of BTEX vapor by the fluorescent film prepared using the fluorescent sensing material BO-CB-CN obtained in Example 1 of the present invention; Figure 8 This is a repeatable spectrum of the response of the fluorescent film prepared using the fluorescent sensing material BO-CB-CN obtained in Example 1 to BTEX vapor; Figure 9 This is a recognition mechanism diagram of the response of the fluorescent film prepared using the fluorescent sensing material BO-CB-CN obtained in Example 1 to BTEX vapor. DETAILED DESCRIPTION

[0051] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0052] Example 1 This embodiment provides a fluorescent sensing material BO-CB-CN, whose structural formula is as follows: , The specific preparation method includes the following contents:

[0053] Step 1: Under an argon atmosphere, add 2,5-dibromo-1,3-difluorobenzene (5.4 g, 20 mmol) and cesium carbonate (16.3 g, 50 mmol) to a 250 mL two-necked flask. Then, add p-tert-butylphenol (6 g, 44 mmol) and 100 mL of N-methylpyrrolidone (NMP) as the reaction solvent. Turn on the heated stirrer and heat the reaction system to 160°C. Stir at 160°C for 48 hours. Turn off the heat and cool to room temperature. Pour the reaction solution into 800 mL of ice water, stir for 1 hour, and let it stand for 12 hours. Filter using a vacuum filtration device, rinse the filter cake with ethanol, and then dry it in an oven to remove moisture. Remove the filter cake and place it in an eggplant-shaped flask. Dissolve it in a small amount of dichloromethane. Separate the mixture by column chromatography using a 300-mesh silica gel column and purify the product using n-hexane as the eluent to obtain O-Br, a pure white solid, in a 93% yield.

[0054]

[0055] Step 2: Under an argon atmosphere, place O-Br (3 g, 5.64 mmol) in a 250 mL two-necked flask and add 30 mL of ultra-dry m-xylene as the solvent. Lower the reaction temperature to -30°C and slowly add a hexane solution of n-butyllithium (1.6 mol / L, 3.70 mL, 5.92 mmol) dropwise. Stir at -30°C for 15 minutes and then at room temperature for 1 hour. Then, lower the reaction temperature again to -30°C and quickly add boron tribromide (0.66 mL, 6.77 mmol). Stir at room temperature for 1 hour. Then, cool the reaction temperature to 0°C using an ice-water bath. Add N,N-diisopropylethylamine (DIPEA, 2.03 mL, 11.68 mmol) and stir for 0.5 hour. Return the reaction to room temperature and heat the reaction to 125°C, refluxing for 24 hours. Finally, the mixture was cooled to room temperature, and 5 mL of methanol was added to the two-necked flask to quench the reaction. The solvent was removed by distillation under reduced pressure, and the product was purified by column chromatography using a 400-mesh silica gel column and n-hexane as the eluent to obtain a pure white solid BO-Br with a yield of 51%.

[0056]

[0057] Step 3: Under an argon atmosphere, BO-Br (0.70 g, 1.5 mmol), p-cyanophenylacetylene (1.014 g, 6.0 mmol), Pd(PPh3)2Cl2 (0.0525 g, 0.075 mmol), and CuI (0.015 g, 0.015 mmol) were added to a dry two-necked flask. Toluene (40 mL) and triethylamine (20 mL) were added to the reaction mixture. The reaction mixture was heated to 110°C for 24 hours, then turned off the heat and cooled to room temperature. The reaction mixture was then extracted with ethyl acetate and water using a separatory funnel. The organic layer was dried over anhydrous Na2SO4 and concentrated. Finally, the solid was dissolved in a small amount of dichloromethane and separated by column chromatography using a 400-mesh silica gel column with a volume ratio of 1:10 dichloromethane to n-hexane as the eluent. The crude product was purified to obtain BO-CN as a yellow solid in a 35% yield.

[0058]

[0059] Step 4: Under an argon atmosphere, a mixture of decaborane (0.72 g, 6.0 mmol) and N,N-dimethylaniline (0.92 g, 6.6 mmol) was added to a dry two-necked flask, followed by the addition of 30 mL of distilled toluene. The mixture was stirred at room temperature for 30 minutes, then the temperature was raised to 100°C and maintained for 2 hours. After cooling to room temperature, BO-CN (1.014 g, 2.0 mmol) was added, and the mixture was refluxed for 12 hours. The heat was turned off again, and after cooling to room temperature, 3 mL of methanol was added to terminate the reaction. The solvent was removed by rotary evaporation, and the residue was separated by column chromatography on a 400-mesh silica gel column using a 1:5 (volume ratio) of dichloromethane and n-hexane as the eluent to obtain BO-CB-CN as a light blue solid in a 31% yield.

[0060] After testing, the NMR data of the BO-CB-CN includes the following: 1 H NMR (400MHz, CDCl3): δ 8.75(d, J = 4.0 Hz, 2 H), 7.81 (d, J = 4.0 Hz, 1 H), 7.79 (d, J = 4.0Hz, 1H), 7.68 (s, 4 H), 7.52 (s, 4H), 7.49 (s, 4 H), 1.49 (s, 18 H), 13C NMR (150 MHz, CDCl3): δ 158.57, 157.11, 145.77, 132.17, 132.11, 130.29, 118.04, 117.37,114.41, 110.84, 84.70, 83.22, 34.61, 31.50 ppm, HRMS (ESI-Orbitrap) m / z: [M+H2O] + calc. for C 35 H 32 B 11 NO3525.2506, found 525.2860. Example 2 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that: in step 3, the volume of triethylamine is 20 mL, and the volume of toluene is 60 mL. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0061] Example 3 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that: in step 3, the volume of triethylamine is 10 mL, and the volume of toluene is 40 mL. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0062] Example 4 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that in step 3, the eluent is dichloromethane-n-hexane in a volume ratio of 1:15. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0063] Example 5 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that in step 3, the eluent is dichloromethane-n-hexane in a volume ratio of 1:20. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0064] Example 6 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that in step 4, the molar ratio of decaborane to N,N-dimethylaniline is 6:7. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0065] Example 7 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that in step 4, the volume of toluene is 35 mL. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0066] Example 8 This embodiment provides a fluorescent sensing material BO-CB-CN, which differs from Example 1 in that in step 4, the volume of toluene is 40 mL. Other steps and parameters are consistent with the embodiment and are not repeated here.

[0067] Example 9 This embodiment provides a fluorescent sensing material H-BO-CB-CN, whose structural formula is as follows: , The specific preparation method includes the following contents:

[0068] Step 1: Under an argon atmosphere, add 2,5-dibromo-1,3-difluorobenzene (5.4 g, 20 mmol) and cesium carbonate (16.3 g, 50 mmol) to a 250 mL two-necked flask. Then, add phenol (4.1 g, 44 mmol) and 100 mL of N-methylpyrrolidone (NMP) as the reaction solvent. Turn on the heating stirrer and heat the reaction system to 160°C. Stir at 160°C for 48 hours. Turn off the heat and cool to room temperature. Pour the reaction solution into 800 mL of ice water, stir for 1 hour, and let it stand for 12 hours. Filter using a vacuum filtration device, rinse the filter cake with ethanol, and then dry it in an oven to remove moisture. Remove the filter cake and place it in an eggplant-shaped flask. Dissolve it in a small amount of dichloromethane. Separate the mixture by column chromatography using a 400-mesh silica gel column and purify the product using n-hexane as the eluent to obtain a pure white solid, HO-Br, in a 94% yield.

[0069]

[0070] Step 2: Under an argon atmosphere, place HO-Br (2.4 g, 5.64 mmol) in a 250 mL two-necked flask and add 30 mL of ultra-dry m-xylene as the solvent. Lower the reaction temperature to -30°C and slowly add a hexane solution of n-butyllithium (1.6 mol / L, 3.70 mL, 5.92 mmol) dropwise. Stir at -30°C for 15 minutes and then at room temperature for 1 hour. Then, lower the reaction temperature again to -30°C and quickly add boron tribromide (0.66 mL, 6.77 mmol). Stir at room temperature for 1 hour. Then, cool the reaction temperature to 0°C using an ice-water bath. Add N,N-diisopropylethylamine (DIPEA, 2.03 mL, 11.68 mmol) and stir for 0.5 hour. Return the reaction to room temperature and heat the reaction to 125°C, refluxing for 24 hours. Finally, the mixture was cooled to room temperature and separated by column chromatography using a 400-mesh silica gel column and n-hexane as the eluent to purify the product to obtain pure white solid H-BO-Br with a yield of 49%.

[0071]

[0072] Step 3: Under an argon atmosphere, H-BO-Br (0.52 g, 1.5 mmol), p-cyanophenylacetylene (1.014 g, 6.0 mmol), Pd(PPh3)2Cl2 (0.0525 g, 0.075 mmol), and CuI (0.015 g, 0.015 mmol) were added to a dry two-necked flask. Toluene (40 mL) and triethylamine (20 mL) were added to the reaction mixture. The reaction mixture was heated to 110°C for 24 hours, then turned off the heat and cooled to room temperature. The reaction mixture was then extracted with ethyl acetate and water using a separatory funnel. The organic layer was dried over anhydrous Na2SO4 and concentrated. Finally, the solid was dissolved in a small amount of dichloromethane and separated by column chromatography using a 400-mesh silica gel column with a volume ratio of 1:10 dichloromethane to n-hexane as the eluent. The crude product was purified to obtain H-BO-CN as a yellow solid in a 35% yield.

[0073]

[0074] Step 4: Under an argon atmosphere, a mixture of decaborane (0.72 g, 6.0 mmol) and N,N-dimethylaniline (0.92 g, 6.6 mmol) was added to a dry two-necked flask, and then 30 mL of distilled toluene was added. Stir at room temperature for 30 minutes, then the temperature was raised to 100°C and continued for 2 hours. After cooling to room temperature, H-BO-CN (0.79 g, 2.0 mmol) was added, and refluxed for 12 hours. After cooling to room temperature, 3 mL of methanol was added to terminate the reaction, and the solvent was removed by rotary evaporation. The residue was separated by column chromatography on a 400-mesh silica gel column using dichloromethane and n-hexane in a volume ratio of 1:5 as eluent to obtain a light blue solid H-BO-CB-CN with a yield of 35%. After testing, the nuclear magnetic resonance data of the H-BO-CB-CN includes the following: 1 H NMR (400 MHz, CDCl3): δ 8.66 (d, 2H), 7.77 (dd, 2H), 7.61 (d, 4H), 7.42 (dd, 4H), 7.28 (s, 2H); 13 C NMR (150 MHz, CDCl3): δ HRMS (ESI-Orbitrap)m / z: [M+H] +calc. for C 27 H 23 B 11 NO2515.2752, found 515.2749. Example 10 This embodiment provides a fluorescent sensing material M-BO-CB-CN, whose structural formula is as follows: , The specific preparation method includes the following contents:

[0075] Step 1: Under an argon atmosphere, add 2,5-dibromo-1,3-difluorobenzene (5.4 g, 20 mmol) and cesium carbonate (16.3 g, 50 mmol) to a 250 mL two-necked flask. Then, add p-methylphenol (4.14 g, 44 mmol) and 100 mL of N-methylpyrrolidone (NMP) as the reaction solvent. Turn on the heated stirrer and heat the reaction system to 160°C. Stir at 160°C for 48 hours. Turn off the heat and cool to room temperature. Pour the reaction solution into 800 mL of ice water, stir for 1 hour, and let it stand for 12 hours. Filter the mixture using a vacuum filtration device. Rinse the filter cake with ethanol and dry it in an oven to remove moisture. Remove the filter cake and place it in an eggplant-shaped flask. Dissolve it in a small amount of dichloromethane. Purify the product by column chromatography using a 300-mesh silica gel column with n-hexane as the eluent to obtain MO-Br, a pure white solid, in a 92% yield.

[0076]

[0077] Step 2: Under an argon atmosphere, MO-Br (2.45 g, 5.64 mmol) was placed in a 250 mL two-necked flask and 30 mL of ultra-dry m-xylene was added as the solvent. The reaction system was cooled to -30°C and a hexane solution of n-butyllithium (1.6 mol / L, 3.70 mL, 5.92 mmol) was slowly added dropwise. After the addition was complete, the mixture was stirred at -30°C for 15 minutes and then at room temperature for 1 hour. The reaction system was then cooled again to -30°C and boron tribromide (0.66 mL, 6.77 mmol) was quickly added. The mixture was then stirred at room temperature for 1 hour. The reaction system was then cooled to 0°C using an ice-water bath. N,N-diisopropylethylamine (DIPEA, 2.03 mL, 11.68 mmol) was added and stirred for 0.5 hours. The mixture was then returned to room temperature and heated to 125°C, where it was refluxed for 24 hours. Finally, the mixture was cooled to room temperature, and 5 mL of methanol was added to the two-necked flask to quench the reaction. The solvent was removed by distillation under reduced pressure, and the product was purified by column chromatography using a 400-mesh silica gel column and n-hexane as the eluent to obtain a pure white solid M-BO-Br with a yield of 52%.

[0078]

[0079] Step 3: Under an argon atmosphere, M-BO-Br (0.60 g, 1.5 mmol), p-cyanophenylacetylene (1.014 g, 6.0 mmol), Pd(PPh3)2Cl2 (0.0525 g, 0.075 mmol), and CuI (0.015 g, 0.015 mmol) were added to a dry two-necked flask. Toluene (40 mL) and triethylamine (20 mL) were added to the reaction mixture, respectively. The reaction mixture was heated to 110°C for 24 hours, then turned off the heat and cooled to room temperature. The reaction mixture was then extracted with ethyl acetate and water using a separatory funnel. The organic layer was dried over anhydrous Na2SO4 and concentrated. Finally, the solid was dissolved in a small amount of dichloromethane and separated by column chromatography using a 400-mesh silica gel column with a volume ratio of dichloromethane to n-hexane of 1:10 as the eluent. The crude product was purified to obtain M-BO-CN as a yellow solid in a 38% yield.

[0080]

[0081] Step 4: Under an argon atmosphere, a mixture of decaborane (0.72 g, 6.0 mmol) and N,N-dimethylaniline (0.92 g, 6.6 mmol) was added to a dry two-necked flask, followed by the addition of 30 mL of distilled toluene. Stirring was carried out at room temperature for 30 minutes, followed by an increase in the temperature to 100°C for 2 hours. After cooling to room temperature, M-BO-CN (0.85 g, 2.0 mmol) was added, and the mixture was refluxed for an additional 12 hours. The heat was turned off again, and after cooling to room temperature, 3 mL of methanol was added to terminate the reaction. The solvent was removed by rotary evaporation, and the residue was separated by column chromatography on a 400-mesh silica gel column using a 1:5 (volume ratio) of dichloromethane and n-hexane as the eluent to obtain M-BO-CB-CN as a light blue solid in a 37% yield.

[0082] After testing, the nuclear magnetic resonance data of the H-BO-CB-CN includes the following: 1 H NMR (400 MHz, CDCl3): δ 8.65 (d, 2H), 7.74 (m, 2H), 7.58 (d, 2H), 7.39 (m, 4H), 7.24 (s, 2H), 1.42(s, 6 H); HRMS (ESI-Orbitrap) m / z: [M+H] + calc. for C 29 H 29 B 11 NO2545.3222, found545.3219. Example 11 This embodiment provides a fluorescent sensing material Ph-BO-CB-CN, whose structural formula is as follows: , The specific preparation method includes the following contents:

[0083] Step 1: Under an argon atmosphere, add 2,5-dibromo-1,3-difluorobenzene (5.4 g, 20 mmol) and cesium carbonate (16.3 g, 50 mmol) to a 250 mL two-necked flask. Then, add p-phenylphenol (7.49 g, 44 mmol) and 100 mL of N-methylpyrrolidone (NMP) as the reaction solvent. Turn on the heated agitator and heat the reaction system to 160°C. Stir at 160°C for 48 hours. Turn off the heat and cool to room temperature. Pour the reaction solution into 800 mL of ice water, stir for 1 hour, and let it stand for 12 hours. Filter the mixture using a vacuum filtration device. Rinse the filter cake with ethanol and dry it in an oven to remove any excess moisture. The filter cake was taken out and placed in an eggplant-shaped flask. A small amount of dichloromethane was added to dissolve it. Column chromatography was performed using a 400-mesh silica gel column. The product was purified using n-hexane as the eluent to obtain a pure white solid Ph-O-Br with a yield of 96%.

[0084]

[0085] Step 2: Under an argon atmosphere, place Ph-O-Br (3.23 g, 5.64 mmol) in a 250 mL two-necked flask and add 30 mL of ultra-dry m-xylene as the solvent. Lower the reaction temperature to -30°C and slowly add a hexane solution of n-butyllithium (1.6 mol / L, 3.70 mL, 5.92 mmol) dropwise. Stir at -30°C for 15 minutes and then at room temperature for 1 hour. Then, lower the reaction temperature again to -30°C and quickly add boron tribromide (0.66 mL, 6.77 mmol). Stir at room temperature for 1 hour. Then, cool the reaction temperature to 0°C using an ice-water bath. Add N,N-diisopropylethylamine (DIPEA, 2.03 mL, 11.68 mmol) and stir for 0.5 hour. Return the reaction to room temperature and heat the reaction to 125°C, refluxing for 24 hours. Finally, the mixture was cooled to room temperature, and 5 mL of methanol was added to the two-necked flask to quench the reaction. The solvent was removed by distillation under reduced pressure, and the product was purified by column chromatography using a 400-mesh silica gel column and n-hexane as the eluent to obtain a pure white solid Ph-BO-Br with a yield of 59%.

[0086]

[0087] Step 3: Under an argon atmosphere, Ph-BO-Br (0.75 g, 1.5 mmol), p-cyanophenylacetylene (1.014 g, 6.0 mmol), Pd(PPh3)2Cl2 (0.0525 g, 0.075 mmol), and CuI (0.015 g, 0.015 mmol) were added to a dry two-necked flask. Toluene (40 mL) and triethylamine (20 mL) were added to the reaction mixture. The reaction mixture was heated to 110°C for 24 hours, then the heat was turned off and cooled to room temperature. The reaction mixture was then extracted with ethyl acetate and water using a separatory funnel. The organic layer was dried over anhydrous Na2SO4 and concentrated. Finally, the solid was dissolved in a small amount of dichloromethane and separated by column chromatography using a 400-mesh silica gel column with a volume ratio of dichloromethane to n-hexane of 1:10 as the eluent. The crude product was purified to obtain Ph-BO-CN as a yellow solid in a 40% yield.

[0088]

[0089] Step 4: Under an argon atmosphere, a mixture of decaborane (0.72 g, 6.0 mmol) and N,N-dimethylaniline (0.92 g, 6.6 mmol) was added to a dry two-necked flask, followed by the addition of 30 mL of distilled toluene. The mixture was stirred at room temperature for 30 minutes, then the temperature was raised to 100°C for 2 hours. After cooling to room temperature, Ph-BO-CN (1.09 g, 2.0 mmol) was added. The mixture was refluxed for 12 hours. The heat was turned off again, and after cooling to room temperature, 3 mL of methanol was added to terminate the reaction. The solvent was removed by rotary evaporation, and the residue was separated by column chromatography on a 400-mesh silica gel column using a 1:5 volume ratio of dichloromethane to n-hexane as the eluent to obtain Ph-BO-CB-CN as a light blue solid in a 41% yield.

[0090] After testing, the nuclear magnetic resonance data of the Ph-BO-CB-CN includes the following: 1 H NMR (400 MHz, CDCl3): δ 8.58 (d, 2H), 7.76 (m, 2H), 7.74 (m, 4H), 7.65 (m, 4H), 7.56 (m, 4H), 7.39(m, 4H), 7.24 (s, 2H); HRMS (ESI-Orbitrap) m / z: [M+H] + calc. forC 39 H 31 B 11 NO2667.3378, found 667.3370. Example 12 This embodiment provides a fluorescent sensing material C-BO-CB-CN, whose structural formula is as follows: and the specific preparation method includes the following contents:

[0091] Step 1: Under an argon atmosphere, add 2,5-dibromo-1,3-difluorobenzene (5.4 g, 20 mmol) and cesium carbonate (16.3 g, 50 mmol) to a 250 mL two-necked flask. Then, add p-cyclohexylphenol (7.75 g, 44 mmol) and 100 mL of N-methylpyrrolidone (NMP) as the reaction solvent. Turn on the heated stirrer and heat the reaction system to 160°C. Stir at 160°C for 48 hours. Turn off the heat and cool to room temperature. Pour the reaction solution into 800 mL of ice water, stir for 1 hour, and let it stand for 12 hours. Filter using a vacuum filtration device, rinse the filter cake with ethanol, and then dry it in an oven to remove moisture. Remove the filter cake and place it in an eggplant-shaped flask. Dissolve it in a small amount of dichloromethane. Separate the mixture by column chromatography using a 400-mesh silica gel column and purify the product using n-hexane as the eluent to obtain a pure white solid, CO-Br, in a 94% yield.

[0092]

[0093] Step 2: Under an argon atmosphere, place CO-Br (3.31 g, 5.64 mmol) in a 250 mL two-necked flask and add 30 mL of ultra-dry m-xylene as the solvent. Lower the reaction temperature to -30°C and slowly add a hexane solution of n-butyllithium (1.6 mol / L, 3.70 mL, 5.92 mmol) dropwise. Stir at -30°C for 15 minutes and then at room temperature for 1 hour. Then, lower the reaction temperature again to -30°C and quickly add boron tribromide (0.66 mL, 6.77 mmol). Stir at room temperature for another hour. Then, lower the reaction temperature to 0°C using an ice-water bath. Add N,N-diisopropylethylamine (DIPEA, 2.03 mL, 11.68 mmol) and stir for 0.5 hours. Return the reaction to room temperature and heat the reaction to 125°C, refluxing for 24 hours. Finally, the mixture was cooled to room temperature, and 5 mL of methanol was added to the two-necked flask to quench the reaction. The solvent was removed by distillation under reduced pressure, and the product was purified by column chromatography using a 400-mesh silica gel column and n-hexane as the eluent to obtain a pure white solid C-BO-Br with a yield of 60%.

[0094]

[0095] Step 3: Under an argon atmosphere, C-BO-Br (0.77 g, 1.5 mmol), p-cyanophenylacetylene (1.014 g, 6.0 mmol), Pd(PPh3)2Cl2 (0.0525 g, 0.075 mmol), and CuI (0.015 g, 0.015 mmol) were added to a dry two-necked flask. Toluene (40 mL) and triethylamine (20 mL) were added to the reaction mixture. The reaction mixture was heated to 110°C for 24 hours, then turned off the heat and cooled to room temperature. The reaction mixture was then extracted with ethyl acetate and water using a separatory funnel. The organic layer was dried over anhydrous Na2SO4 and concentrated. Finally, the solid was dissolved in a small amount of dichloromethane and separated by column chromatography on a 400-mesh silica gel column using a 1:10 volume ratio of dichloromethane to n-hexane as the eluent. The crude product was purified to obtain C-BO-CN as a yellow solid in a 42% yield.

[0096]

[0097] Step 4: Under an argon atmosphere, a mixture of decaborane (0.72 g, 6.0 mmol) and N,N-dimethylaniline (0.92 g, 6.6 mmol) was added to a dry two-necked flask, followed by the addition of 30 mL of distilled toluene. Stirring was carried out at room temperature for 30 minutes, followed by an increase in the temperature to 100°C for 2 hours. After cooling to room temperature, C-BO-CN (1.12 g, 2.0 mmol) was added, and the mixture was refluxed for another 12 hours. The heat was turned off again, and after cooling to room temperature, the reaction was terminated by the addition of 3 mL of methanol. The solvent was removed by rotary evaporation, and the residue was separated by column chromatography on a 400-mesh silica gel column using a 1:5 (volume ratio) of dichloromethane and n-hexane as the eluent to obtain C-BO-CB-CN as a light blue solid in a 41% yield.

[0098] After testing, the nuclear magnetic resonance data of the C-BO-CB-CN includes the following: 1 H NMR (400 MHz, CDCl3): δ 8.55 (d, 2H), 7.73 (d, 2H), 7.74 (m, 2H), 7.58 (m, 2H), 7.56 (m, 2H), 7.39(m, 2H), 2.85 (m, 2H), 2.01 (m, 4H), 1.65~1.83 (m, 16H),; HRMS (ESI-Orbitrap)m / z: [M+H] + calc. for C 39 H 43 B 11 NO2679.4317, found 679.4312. In order to further demonstrate the technical effect of the present invention, the present invention prepared fluorescence sensors using the fluorescent sensing materials obtained in Examples 1-12, respectively. The specific operation steps are as follows: Step 1: Dissolve the compounds in toluene (TOL) to prepare 1×10 -5 mol / L fluorescent probe stock solution, for future use; Step 2: Place 100 mL of distilled water in a beaker, add 0.5 g of sodium carboxymethyl cellulose, and stir on a magnetic stirrer for 8 hours. Then, add 3 g of silica gel powder and stir for another 24 hours. Use a polyurethane sheet as the substrate, evenly apply the prepared silica gel to the sheet, and allow it to dry naturally in a dark place.

[0099] Step 3: Pipette 20 μL of the mother solution and drop it on the surface of the prepared silica gel sheet, place it in the air to dry naturally, and then store it in a vacuum desiccator for later use.

[0100] The present invention conducted the following tests on the fluorescent sensing material obtained in Example 1 and the fluorescent thin film sensor prepared using the fluorescent sensing material obtained in Example 1: 50 mL of the analyte (analytical grade) was taken into a 5 L brown glass bottle, and then placed under the test pressure (995 hPa) and temperature (293 K) for 12 hours to achieve a gas-liquid equilibrium state. At this time, the gas above the liquid in the bottle can be considered as saturated vapor, and then a syringe can be used to aspirate the saturated vapor above the bottle for subsequent testing.

[0101] The prepared fluorescent film sensor was placed in a sensing platform, and different types of saturated analyte gases were drawn in with a glass syringe. Each time, 5-10 mL of sample was injected into the chamber of the sensing unit through the syringe at a speed of 1.25-1.50 mL / s, so that it came into contact with the fluorescent film, thereby obtaining a response signal and a curve of the fluorescence intensity changing with time, thereby exploring the selectivity of the fluorescent film for BTEX.

[0102] The prepared fluorescent film sensor was placed in a sensing platform. Saturated BTEX vapor was drawn in with a glass syringe and diluted to different concentrations by aspirating air. 5-10 mL of sample was injected into the chamber of the sensing unit at a rate of 1.25-1.50 mL / s via a syringe, allowing it to contact the fluorescent film. A response signal was obtained, and a curve of fluorescence intensity changing with time was obtained to explore the sensing ability of the fluorescent film for BTEX, a benzene series. The experimental results are shown in Figure 2. Figure 4-9 shown.

[0103] Figure 4 The normalized graph of the UV-visible absorption spectrum and fluorescence emission spectrum of the fluorescent compound BO-CB-CN in toluene solution; the solid line is the UV-visible absorption spectrum, and the dotted line is the fluorescence emission spectrum. Figure 4The UV-visible absorption spectrum of BO-CB-CN shows absorption peaks at 286 and 386 nm, with a maximum absorption wavelength at 386 nm. Fluorescence emission spectroscopy indicates that the maximum emission wavelength of BO-CB-CN is 634 nm. Based on these data, it can be calculated that BO-CB-CN has a large Stokes shift of 248 nm.

[0104] Figure 5 This is a side view of the photochemical stability of the BO-CB-CN based thin film sensor; under continuous light irradiation for nearly 5 hours, the fluorescence intensity of the BO-CB-CN based thin film only decreased by 6.73%, which shows that the BO-CB-CN based fluorescence sensor has excellent photostability, laying the foundation for subsequent detection.

[0105] Figure 6 The selectivity of BO-CB-CN based thin film sensors for BTEX detection was studied. Figure 6 As can be seen, while the BO-CB-CN film exhibited a quenched fluorescence response to the same concentration of VOC vapor tested (6900 ppm), the quenching efficiency was generally low (<5%), and the film was virtually unaffected by water vapor. However, when BTEX vapors (benzene, toluene, or xylene) were pumped into the detection system, the fluorescence intensity of the BO-CB-CN film decreased significantly. Specifically, for BTEX, at the same concentration, benzene had the lowest quenching efficiency, approximately 5%, followed by toluene, at approximately 10%. Ethylbenzene, o-xylene, and p-xylene achieved quenching efficiencies of 15%, while m-xylene had the highest quenching efficiency, reaching 20%. Therefore, the sensor exhibits excellent selectivity for BTEX vapors.

[0106] Figure 7 This study investigated the detection limits of BTEX vapor using a BO-CB-CN-based thin-film sensor. To ensure the reliability of the experimental results, the measurements were repeated three times for each concentration. The results showed that the detection limits for benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene were lower than 30.9 ppm, 44.8 ppm, 34.7 ppm, 44.6 ppm, 30.86 ppm, and 69.4 ppm, respectively.

[0107] Figure 8 The research on the responsiveness of BO-CB-CN based thin film sensors to BTEX gas; Figure 8 It can be seen that the fluorescence intensity of the BO-CB-CN based thin film sensor can still be restored to the initial value after 10 cycles of detection of each BTEX gas, indicating that the film has excellent reusability.

[0108] Figure 9This study investigates the response of BO-CB-CN based thin film sensors to binary vapors. In practical applications of thin film sensors, the analytes are often complex, and sometimes analysis and testing is not performed on a single component. Therefore, we tested the sensor's sensing performance for mixed vapors of benzene and o-xylene. The results show that as the o-xylene content increases, the fluorescence response time also increases. Figure 9 It can be seen that the benzene content and the response time show a good linear correlation. Based on the above research, the BO-CB-CN based thin film sensor has great potential in practical applications.

[0109] In summary, we have developed a nonplanar boron-oxygen multiple resonance thin-film fluorescence sensor for detecting BTEX vapor. This sensor exhibits excellent selectivity, high sensitivity, and simple operation, enabling real-time, online, in-situ detection. The sensor exhibits a response time of 4 seconds for BTEX vapor, with experimental detection limits of 30.9 ppm, 44.8 ppm, 34.7 ppm, 44.6 ppm, 30.86 ppm, and 69.4 ppm, respectively. The prepared thin-film sensor is reusable, significantly reducing production costs. Therefore, this thin-film fluorescence sensor has broad application prospects in industrial environmental monitoring, air quality assessment, and volatile organic compound analysis. With further optimization and integration, it is expected to be incorporated into portable detection devices, providing a powerful tool for rapid on-site detection.

[0110] 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 or 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 fluorescent sensing material, characterized in that: The structural formula of the fluorescent sensing material is shown in Formula 1: Formula 1 Wherein, R1 and R2 can be independently selected from -H, -X (X is any one of F, Cl, Br or I), C1-C 10 Alkyl, C1-C 10 Cycloalkyl, C1-C 10 Alkoxy, C6-C 60 Aromatic ring or C3-C 60 Any one of the aromatic heterocyclic groups and their derivatives.

2. The fluorescent sensing material according to claim 1, wherein: The R1 and R2 can be independently selected from any one of -H, -X (X is any one of F, Cl, Br or I), -CH3, -CH2CH3, -CH(CH3)2, -CH(CH3)CH2CH3, -CH2C(CH3)3, -CH2(CH2)5CH3, cyclopropyl, tert-butyl, cyclobutyl, cyclopentyl or cyclohexyl.

3. The method for preparing the fluorescent sensing material according to claim 1 or 2, wherein: The steps include: Step 1: In an inert atmosphere, 2,5-dibromo-1,3-difluorobenzene, basic salt and R-Ar-OH are mixed uniformly, dissolved in an organic solvent, and reacted at 100-110°C to obtain intermediate 1; Step 2: Dissolve the intermediate 1 in an aromatic solvent in an inert atmosphere, add n-butyl lithium, boron tribromide and a neutralizing stabilizer in sequence, mix well, and heat under reflux to obtain intermediate 2; Step 3: In an inert atmosphere, the intermediate 2, p-cyanophenylacetylene and an organic catalyst are uniformly mixed and dissolved in a mixed organic amine solvent, and a coupling reaction is carried out at 110-115° C. to obtain intermediate 3; Step 4: In an inert atmosphere, decaborane and an activator are mixed evenly, dissolved in a phenyl solvent, and activated at 110-115° C., cooled to obtain an activated reaction solution; the intermediate 3 is added to the activated reaction solution to carry out an alkyne-hydrogen addition reaction to obtain a fluorescent sensing material.

4. The method for preparing the fluorescent sensing material according to claim 3, wherein: In step 1, the basic salt is cesium carbonate; and / or In step 1, the organic solvent is N-methylpyrrolidone; and / or In step 1, the molar ratio of 2,5-dibromo-1,3-difluorobenzene, basic salt and R-Ar-OH is 1:2.5:2.2-1:2.5:2.5; and / or In step 1, the mass volume ratio of the total mass of the 2,5-dibromo-1,3-difluorobenzene, the basic salt and R-Ar-OH to the organic solvent is 1g:3mL-1g:4mL; and / or In step 1, the reaction time is 36-48 hours.

5. The method for preparing the fluorescent sensing material according to claim 3, wherein: In step 2, the aromatic solvent is m-xylene; and / or In step 2, the neutralizing stabilizer is N,N-diisopropylethylamine; and / or In step 2, the molar ratio of the intermediate 1, n-butyl lithium, boron tribromide and neutralizing stabilizer is 1:1.05:1.2:2.07-1:1.06:1.24:2.07; and / or In step 2, the mass volume ratio of the intermediate 1 to the aromatic solvent is 1 g:10 mL-1 g:15 mL; and / or In step 2, the reflux time is 12-24 hours.

6. The method for preparing the fluorescent sensing material according to claim 3, wherein: In step 3, the organic catalyst is Pd(PPh3)2Cl2 and CuI in a molar ratio of 0.05:0.01-0.05:0.02; and / or In step 3, the mixed organic amine solvent is toluene and triethylamine in a volume ratio of 1:1-4:1; and / or In step 3, the mass volume ratio of the total mass of the intermediate 2, p-cyanophenylacetylene and the organic catalyst to the mixed organic amine solvent is 1g:25mL-1g:50mL; and / or In step 3, the coupling reaction time is 12-24 hours.

7. The method for preparing the fluorescent sensing material according to claim 6, wherein: In step 3, the molar ratio of the intermediate 2, p-cyanophenylacetylene and Pd(PPh3)2Cl2 in the organic catalyst is 1:4:0.05-1:4:0.

1.

8. The method for preparing the fluorescent sensing material according to claim 3, wherein: In step 4, the activating agent is N,N-dimethylaniline; and / or In step 4, the activation reaction time is 2-3 hours; and / or In step 4, the molar ratio of decaborane, activator and intermediate 3 is 1:1.1:0.33-1:1.17:0.33; and / or In step 4, the mass volume ratio of the total mass of the decaborane and the activator to the phenyl solvent is 1g:15mL-1g:25mL; and / or In step 4, the reaction temperature of the alkyne-hydrogen addition reaction is 110-115° C., and the time of the alkyne-hydrogen addition reaction is 12-24 h.

9. A fluorescent thin film sensor, characterized in that: It is prepared using the fluorescent sensing material according to claim 1 or 2.

10. Use of the fluorescent thin film sensor according to claim 9 in detecting BTEX gas.

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