Application of thiazolothiazole fluorescent derivative in sensing detection of butyl nitrite

Abstract

This invention discloses the application of a thiazo[a]thiazolium fluorescent derivative in the sensing and detection of butyl nitrite. This fluorescent derivative uses the electron-deficient thiazo[a]thiazolium group as the core, with symmetrically connected at both ends a benzene ring with a typical "propeller" conformation and methoxylated triphenylamine at the para- or ortho-position as electron donors, forming a D-A-D type structure. This derivative exhibits high fluorescence quantum yield, excellent intramolecular charge transfer (ICT) characteristics, and good photophysical properties, demonstrating excellent sensing performance for butyl nitrite, including high sensitivity, fast response speed, and short recovery time. Furthermore, this fluorescent derivative is prepared into a fluorescent sensing film with good photochemical stability using a drop-coating method, and then assembled into a device to construct a thin-film fluorescent sensor, demonstrating significant application potential and practical value in the high-sensitivity detection of butyl nitrite.

Description

Technical Field

[0001] This invention belongs to the field of nitrite detection technology, specifically relating to the sensing and detection application of thiazothiazol derivatives of nitrite. Background Technology

[0002] Nitrite compounds are typical examples of sexual stimulants. Upon inhalation, they release nitric oxide, causing rapid vasodilation. Long-term or excessive exposure can induce serious cardiovascular and neurological diseases, leading to increasingly stringent regulations in many countries. Butyl nitrite, due to its high vapor pressure and rapid diffusion, is easily abused and is one of the most representative compounds in this class. These characteristics make butyl nitrite a dangerous volatile chemical, posing a threat not only to individual health but also increasing safety hazards in public places due to its volatility. Therefore, there is an urgent need to develop new materials capable of rapid and sensitive on-site detection to meet the application needs of various scenarios such as environmental monitoring, public place security checks, and clinical emergency care.

[0003] Currently, the main methods for detecting nitrite compounds include gas chromatography, mass spectrometry, and electrochemical analysis. However, these methods typically rely on expensive, large-scale instruments, complex sample pretreatment processes, and specialized operators, making them unsuitable for rapid, real-time on-site detection. In contrast, fluorescence sensing technology, with its high sensitivity, rapid optical response, and good compatibility with solid-state devices, has become an ideal platform for the detection of volatile organic compounds. Thin-film fluorescence sensing technology, in particular, eliminates the need for complex sample pretreatment to complete signal conversion, making it especially suitable for real-time, on-site monitoring of volatile organic gases. This technology achieves reversible and continuous response to analytes by fixing fluorescent materials onto a substrate surface, demonstrating significant advantages in the development of portable sensor devices.

[0004] For electron-deficient volatile organic compounds (VOCs), electron-rich fluorescent materials can, in principle, achieve effective signal modulation through photoinduced electron transfer. When the analyte comes into contact with fluorescent molecules, the electron transfer between them can lead to fluorescence quenching or enhancement, thereby enabling the output of a detection signal. However, despite the thermodynamic feasibility of photoinduced electron transfer, it still faces many challenges in practical sensing applications. First, the close packing of molecules in solid-state systems often leads to exciton coupling and self-absorption, weakening the fluorescence response efficiency. Second, the feasibility of molecular recognition and dynamics is highly dependent on molecular conformation and spatial arrangement, both of which have a decisive influence on the photoinduced electron transfer process. Specifically, the molecular packing pattern, the distance and orientation between donor and acceptor molecules, and the diffusion rate of the analyte in the thin film all directly affect the efficiency and reversibility of electron transfer. Therefore, how to regulate the electronic structure and aggregation behavior of fluorescent materials at the molecular level to optimize the photoinduced electron transfer process remains a key scientific problem in designing high-performance sensing materials.

[0005] To address the aforementioned challenges, researchers have recently focused on developing novel fluorescent sensing materials using molecular engineering strategies. Among these, molecules with a donor-acceptor-donor (DAD) configuration have attracted widespread attention due to their tunable energy levels, excellent charge transfer properties, and good thin-film stability. Thiazolothiazole, as an electron-deficient heterocyclic unit, possesses strong electron-withdrawing capabilities, making it suitable for constructing DAD-type fluorescent molecules. Meanwhile, triphenylamine and its derivatives, with their typical "propeller" conformation and electron-rich characteristics, can effectively suppress intermolecular π-π stacking, thereby improving solid-state luminescence efficiency. Combining these two technologies not only promises to achieve efficient intramolecular charge transfer processes but also allows for optimization of the film's microstructure by controlling molecular conformation, thus enhancing the analyte recognition ability and electron transfer efficiency. Based on this, a series of DAD-type fluorescent derivatives with thiazothiazole as the core and triphenylamine as the donor have been synthesized in existing technologies. These compounds exhibit excellent intramolecular charge transfer properties and high fluorescence quantum yields due to their unique donor-acceptor structure, demonstrating potential application value in fields such as optoelectronic materials. However, its sensing performance in the field of volatile organic compound detection, especially for nitrite compounds, still needs further exploration. Summary of the Invention

[0006] The purpose of this invention is to provide the application of thiazothiazol fluorescent derivatives as fluorescent probes in the sensing detection of butyl nitrite, aiming to provide new material selection and theoretical basis for the rapid and highly sensitive detection of nitrite compounds.

[0007] The structural formula of the thiazothiazol fluorescent derivative is shown below:

[0008]

[0009] In the formula, R1 represents -H and R2 represents -OCH3, or R1 represents -OCH3 and R2 represents -H.

[0010] The method for using the above-mentioned thiazothiazol derivative as a fluorescent probe to detect butyl nitrite is as follows: The thiazothiazol fluorescent derivative is added to an organic solvent to prepare a solution of 1×10⁻⁶. -4 ~1×10 -3 A fluorescent probe solution of mol / L was prepared; then the fluorescent probe solution was drop-coated onto a glass plate and dried to obtain a fluorescent sensing film for sensing and detecting butyl nitrite.

[0011] Furthermore, the organic solvent is preferably toluene or dichloromethane.

[0012] Furthermore, the fluorescent sensing film can also be fabricated into a thin-film fluorescent sensor for sensing and detecting butyl nitrite vapor.

[0013] The beneficial effects of this invention are as follows:

[0014] The thiazo[5,4-d]thiazole derivative of this invention uses a rigid planar electron acceptor unit, thiazo[5,4-d]thiazole, with excellent photoluminescence properties, as the core. A DAD structure is constructed by introducing methoxy groups at different positions on the benzene ring surrounding triphenylamine as electron donors. The "propeller" geometry of triphenylamine has unique structural advantages, laying the foundation for finely controlling its electron distribution and spatial configuration through site substitution. This derivative exhibits different donor strengths and spatial conformations, high fluorescence quantum yield, and significant fluorescence color-changing effects in solvents of different polarities. Its emission spectrum shows a significant red shift with increasing solvent polarity, exhibiting typical intramolecular charge transfer (ICT) characteristics and excellent photophysical properties. This derivative demonstrates excellent sensing performance for butyl nitrite. The thiazo[5,4-d]thiazole derivative is prepared into a fluorescent sensing film with excellent photochemical stability using a drop-coating method, and further device-assembled into a thin-film fluorescent sensor. Performance test results show that this sensor has the following outstanding advantages in detecting butyl nitrite vapor: extremely high sensitivity, with a detection limit as low as 6.4 ppt, meeting the needs of trace detection; rapid response, with a response time of less than 5 seconds, suitable for real-time rapid early warning; good reversibility, maintaining a stable signal output after multiple cycles, demonstrating excellent reusability; and excellent selectivity, exhibiting a specific response to butyl nitrite and unaffected by interference from common coexisting volatile organic compounds. Therefore, this invention achieves high-sensitivity, high-selectivity, rapid, and reversible detection of butyl nitrite. Furthermore, the fabrication process of this type of sensor film is simple, stable, and highly modular, showing broad application prospects and significant practical value in environmental monitoring, public safety, and rapid clinical detection. Attached Figure Description

[0015] Figure 1 These are the UV-Vis absorption spectra of TTz-1 at different concentrations in DCM.

[0016] Figure 2 These are the fluorescence emission spectra of TTz-1 at different concentrations in DCM.

[0017] Figure 3 The UV-Vis absorption spectra of TTz-1 in different solvents (concentration 1×10⁻⁶) -5 mol / L).

[0018] Figure 4 The fluorescence emission spectra of TTz-1 in different solvents (concentration 1×10⁻⁶) -5 mol / L; excitation wavelength: 440 nm.

[0019] Figure 5These are the UV-Vis absorption spectra of TTz-2 at different concentrations in DCM.

[0020] Figure 6 These are the fluorescence emission spectra of TTz-2 at different concentrations in DCM.

[0021] Figure 7 The UV-Vis absorption spectra of TTz-2 in different solvents (concentration 1×10⁻⁶) -5 mol / L).

[0022] Figure 8 The fluorescence emission spectra of TTz-2 in different solvents (concentration 1×10⁻⁶) -5 mol / L; excitation wavelength: 420 nm.

[0023] Figure 9 This is the UV-Vis absorption spectrum of TTz-1 in DCM titrated with butyl nitrite (concentration 1×10⁻⁶). -5 mol / L).

[0024] Figure 10 This is the fluorescence emission spectrum of TTz-1 in DCM titrated with butyl nitrite (concentration 1×10⁻⁶). -5 mol / L; excitation wavelength: 440 nm).

[0025] Figure 11 This is the UV-Vis absorption spectrum of TTz-2 in DCM titrated with butyl nitrite (concentration 1×10⁻⁶). -5 mol / L).

[0026] Figure 12 This is the fluorescence emission spectrum of TTz-2 in DCM titrated with butyl nitrite (concentration 1×10⁻⁶). -5 mol / L; excitation wavelength: 420 nm).

[0027] Figure 13 These are the stability test results for TTz-1 and TTz-2 fluorescent sensing films (excitation wavelengths of 440 nm and 420 nm, respectively).

[0028] Figure 14 These are the sensitivity test results of the TTz-1 fluorescent sensing film to different concentrations of butyl nitrite vapor.

[0029] Figure 15 These are the sensitivity test results of the TTz-2 fluorescent sensing film to different concentrations of butyl nitrite vapor.

[0030] Figure 16 These are the sensing kinetics results of TTz-1 and TTz-2 fluorescent sensing films for butyl nitrite vapor.

[0031] Figure 17 These are the test results of the reversibility of butyl nitrite vapor on the TTz-1 fluorescent sensing film.

[0032] Figure 18 These are the test results of the reversibility of butyl nitrite vapor to the TTz-2 fluorescent sensing film.

[0033] Figure 19 These are the results of the selectivity test of TTz-1 fluorescent sensing film for butyl nitrite vapor.

[0034] Figure 20 These are the results of the selectivity test of TTz-2 fluorescent sensing film for butyl nitrite vapor. Detailed Implementation

[0035] The technical solutions of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the specific embodiments are only for illustrating the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

[0036] Example 1

[0037] 1. Synthesis of thiazothiazol derivatives

[0038] Under anhydrous and oxygen-free conditions, a mixture of dithioacetamide (0.60 g, 5 mmol) and 4-[bis(4-methoxyphenyl)amino]benzaldehyde (3.70 g, 11 mmol) was added to a 50 mL double-necked round-bottom flask, followed by 30 mL of DMF. The mixture was refluxed at 150 °C for 8 h. After the reaction was complete, the reaction solution was cooled to room temperature, extracted with dichloromethane and washed with water. Water was removed with anhydrous sodium sulfate, and the organic solvent was removed by rotary evaporation. The mixture was purified by column chromatography (using a mixture of ethyl acetate and n-hexane in a volume ratio of 4:1). Finally, the mixture was recrystallized from dichloromethane / n-hexane and dried under vacuum to give 2.52 g of the yellow compound TTz-1, with a yield of 68%.

[0039]

[0040] The structural characterization results of TTz-1 are as follows: 1 H NMR (600 MHz, CDCl3): δ (ppm) 7.90 (d, 4H),7.79 (d, 4H), 7.12 (d, 8H), 6.87 (d, 8H), 3.82 (s, 12H); APCI-HRMS: [(M+H)]+ (C 44 H 36 N4O4S2): Theoretical value 749.2251, actual value 749.2243.

[0041] Under anhydrous and oxygen-free conditions, a mixture of dithioacetamide (0.60 g, 5 mmol) and 4-(bis(2-methoxyphenyl)amino)benzaldehyde (3.70 g, 11 mmol) was added to a 50 mL double-necked round-bottom flask, along with 30 mL of DMF. The mixture was refluxed at 150 °C for 12 h. After the reaction was complete, the reaction solution was cooled to room temperature, extracted with dichloromethane and washed with water. Water was removed with anhydrous sodium sulfate, and the organic solvent was removed by rotary evaporation. The mixture was purified by column chromatography (using a methanol:dichloromethane mixture of 1:50 v / v). Finally, it was recrystallized from dichloromethane / n-hexane and dried under vacuum to give 1.50 g of the yellow compound TTz-2, with a yield of 40%.

[0042]

[0043] The structural characterization results of TTz-2 are as follows: 1 H NMR (600 MHz, CDCl3): δ (ppm) 7.74 (d, 4H),7.25 (t, 8H), 6.97 (t, 8H), 6.60 (d, 4H), 3.73 (s, 12H); APCI-HRMS: [(M+H)] + (C 44 H 36 N4O4S2): Theoretical value 749.2251, actual value 749.2254.

[0044] Dissolve TTz-1 in DCM to prepare a concentration of 1.0 × 10⁻⁶. -6 mol / L~1.0×10 -5 The UV-Vis absorption and fluorescence emission spectra of a mol / L TTz-1 solution were measured, and the results are shown in the figure. Figure 1 and Figure 2 .Depend on Figure 1 The UV-Vis absorption spectrum shows that the maximum absorption peak wavelength of TTz-1 is located at 280 and 440 nm. As the concentration of TTz-1 increases, the intensity of its maximum absorption peak gradually increases, while the shape and position of its characteristic absorption peak do not change significantly, indicating that within this concentration range, TTz-1 does not undergo association or dissociation in the DCM. Figure 2The fluorescence emission spectrum shows that the maximum emission wavelength of TTz-1 is 570 nm. Within the measured concentration range, the intensity of the maximum emission peak of TTz-1 is proportional to the concentration, and the peak shape and position do not change significantly, indicating that TTz-1 does not have an aggregation-induced quenching effect.

[0045] TTz-1 was dissolved in different solvents to prepare solutions with a concentration of 1.0 × 10⁻⁶. -5 To investigate the solvent-dependent effect of a mol / L TTz-1 solution. Figure 3 The UV-Vis absorption spectrum shows that changing the solvent polarity did not alter the wavelength of the UV-Vis absorption peak, indicating that the solvent polarity has almost no effect on the electronic structure of the TTz-1 ground state. Figure 4 As can be seen from the fluorescence emission spectrum, with the increase of solvent polarity, the maximum emission peak of TTz-1 exhibits a significant red shift, and the amplitude of the solvent-induced color change effect (Δλ) increases. em The value of 70 nm indicates that TTz-1 has intramolecular charge transfer properties.

[0046] Dissolve TTz-2 in DCM to prepare a solution with a concentration of 1.0 × 10⁻⁶. -6 mol / L~1.0×10 -5 The UV-Vis absorption and fluorescence emission spectra of a mol / L TTz-2 solution were measured, and the results are shown in the figure. Figure 5 and Figure 6 .Depend on Figure 5 The UV-Vis absorption spectrum shows that the maximum absorption peak of TTz-2 is located at 420 nm. As the concentration of TTz-2 increases, the intensity of the maximum absorption peak gradually increases, while the shape and position of its characteristic absorption peak do not change significantly, indicating that within this concentration range, TTz-2 does not undergo association or dissociation in the DCM. Figure 6 The fluorescence emission spectrum shows that the maximum emission wavelength of TTz-2 is 480 nm. Within the measured concentration range, the intensity of the maximum emission peak of TTz-2 is proportional to the concentration, and the peak shape and position do not change significantly, indicating that TTz-2 does not have an aggregation-induced quenching effect.

[0047] TTz-2 was dissolved in different solvents to prepare solutions with a concentration of 1.0 × 10⁻⁶. -5 To investigate the solvent-dependent effect of a mol / L TTz-2 solution. Figure 7 The UV-Vis absorption spectrum shows that changing the solvent polarity did not alter the wavelength of the UV-Vis absorption peak, indicating that the solvent polarity has almost no effect on the electronic structure of the TTz-2 ground state. Figure 8 As can be seen from the fluorescence emission spectrum, with the increase of solvent polarity, the maximum emission peak of TTz-2 exhibits a significant red shift, and the amplitude of the solvent-induced color change effect (Δλ) increases.em The value of 15 nm indicates that TTz-2 has intramolecular charge transfer properties.

[0048] 2. Application of thiazothiazol fluorescent derivatives as fluorescent probes in the detection of butyl nitrite.

[0049] Titration experiments were performed on a DCM solution of TTz-1, and the UV-Vis absorption and fluorescence emission spectra before and after the addition of butyl nitrite were measured and studied. Figure 9 and Figure 10 The UV-Vis absorption and fluorescence emission spectra show that no new absorption or emission peaks appeared with the titration of butyl nitrite. Only a very weak enhancement was observed in its absorption peak. The fluorescence intensity decreased significantly and monotonically with the increase of analyte concentration, and the spectral shape remained unchanged. This quenching phenomenon may be due to transient collisions of the excited state of the compound.

[0050] Titration experiments were conducted on a DCM solution of TTz-2, and the UV-Vis absorption and fluorescence emission spectra before and after the addition of butyl nitrite were measured and studied. Figure 11 and Figure 12 The UV-Vis absorption and fluorescence emission spectra show that, with the titration of butyl nitrite, new peaks appear in the UV-Vis absorption spectrum at 445 nm and the fluorescence emission spectrum at 588 nm. These phenomena strongly suggest that TTz-2 and butyl nitrite have undergone ground-state interaction, possibly forming a new chemical species.

[0051] Since TTz-1 and TTz-2 are responsive to butyl nitrite, they were fabricated into fluorescent sensing films to detect butyl nitrite vapor. The specific method involved adding TTz-1 and TTz-2 separately to dichloromethane to prepare a 1×10⁻⁶ film. -4 30 μL of 1×10 mol / L TTz-1 and TTz-2 dichloromethane solutions; -4 TTz-1 and TTz-2 dichloromethane solutions of mol / L were drop-coated onto a glass plate and dried to obtain TTz-1 fluorescent sensing film and TTz-2 fluorescent sensing film, respectively.

[0052] The stability of the TTz-1 and TTz-2 fluorescent sensing films was investigated on the sensing platform. The films were continuously irradiated with 440 nm (TTz-1) and 420 nm (TTz-2) ​​lamps for 10 h, respectively. It was observed that the fluorescence intensity of the TTz-1 fluorescent sensing film quenched by only 0.24%, while that of the TTz-2 fluorescent sensing film quenched by 4.93% (see...). Figure 13 ).

[0053] Sensing sensitivity tests on the TTz-1 and TTz-2 fluorescent sensing films showed that both films can detect butyl nitrite vapor at the ppt level (see [link to relevant documentation]). Figure 14 , Figure 15 This indicates that TTz-1 and TTz-2 fluorescent sensing films hold promise for the detection of ultra-low concentrations of butyl nitrite.

[0054] In addition, the response kinetics of TTz-1 and TTz-2 fluorescent sensing films to butyl nitrite vapor were analyzed in detail (see...). Figure 16 The sensing process was indexed and quantified to evaluate the sensing performance of the TTz-1 and TTz-2 fluorescent sensing films at a deeper level. The response times of the fluorescent sensing films to butyl nitrite vapor were both less than 5 s. After sample injection was stopped, the signal began to rise. The recovery time of the TTz-1 sensing film (defined as the time it takes for the output to recover from its maximum intensity to 90% of its initial intensity) was 38 s, and that of the TTz-2 sensing film was 43 s. The excellent reversibility, fast response time, and short recovery period exhibited by the sensing films demonstrate that the TTz-1 and TTz-2 fluorescent sensing films of this invention are valuable for manufacturing practically applicable thin-film-based fluorescent sensors.

[0055] Further reversibility sensing tests were conducted on the TTz-1 and TTz-2 fluorescent sensing films for butyl nitrite vapor, such as... Figure 17 and Figure 18 As shown, at low butyl nitrite vapor concentrations, the TTz-1 fluorescent sensing film exhibited near-complete reversibility in its fluorescence response to butyl nitrite vapor over at least 30 cycles, while the TTz-2 fluorescent sensing film showed near-complete reversibility in its fluorescence response to butyl nitrite vapor over at least 50 cycles, with only a slight decrease in film performance and fluorescence response intensity. This sensing test demonstrates that the fluorescent sensing film has good reusability and can achieve continuous real-time monitoring of butyl nitrite vapor.

[0056] The selective detection results of TTz-1 and TTz-2 fluorescent sensing films for butyl nitrite are shown in the figure. Figure 19 and Figure 20 As shown in the figure, compared with some common VOCs gases (acid gases, ester gases, and common highly volatile organic solvents), the response intensity of butyl nitrite vapor is the largest, indicating that the obtained TTz-1 fluorescent sensing film and TTz-2 fluorescent sensing film have good selectivity for the detection of butyl nitrite vapor.

[0057] In summary, the TTz-1 and TTz-2 fluorescent sensing films of the present invention exhibit good performance in terms of stability, selectivity, and reusability in the detection of butyl nitrite vapor, with actual detection limits as low as 6.4 ppt.

Claims

1. The use of a thiazothiazol fluorescent derivative in the sensing detection of butyl nitrite, wherein the structural formula of the thiazothiazol fluorescent derivative is shown below: In the formula, R1 represents -H and R2 represents -OCH3, or R1 represents -OCH3 and R2 represents -H.

2. The use of the thiazothiazolium fluorescent derivative according to claim 1 in the sensing detection of butyl nitrite, characterized in that: Thiazolothiazole fluorescent derivatives were added to an organic solvent to prepare a solution of 1×10⁻⁶. -4 ~1×10 -3 A fluorescent probe solution of mol / L was prepared; then the fluorescent probe solution was drop-coated onto a glass plate and dried to obtain a fluorescent sensing film for sensing and detecting butyl nitrite.

3. The use of the thiazothiazolium fluorescent derivative according to claim 2 in the sensing detection of butyl nitrite, characterized in that: The organic solvent is toluene or dichloromethane.

4. The use of the thiazothiazolium fluorescent derivative according to claim 2 in the sensing detection of butyl nitrite, characterized in that: The fluorescent sensing film is fabricated into a thin-film fluorescent sensor for sensing and detecting butyl nitrite vapor.

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