Application of pyrene-containing fluorescent probe in detection of straight-chain aliphatic alcohol compounds

Abstract

This invention discloses the application of a pyrene-containing fluorescent probe in the detection of straight-chain fatty alcohols, belonging to the field of lyochromic organic small molecule fluorescent probe technology. The structural formula of the pyrene-containing fluorescent probe is shown in formula (1): where R is hydrogen or iodine. This pyrene-containing fluorescent probe can produce ratiometric dual fluorescence emission dependent on the carbon chain length of straight-chain fatty alcohols, and has ratiometric response capability to structurally similar straight-chain fatty alcohol homologues such as methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol, and can be used in the detection of straight-chain fatty alcohols.

Description

Technical Field

[0001] This invention belongs to the field of lyochromic organic small molecule fluorescent probe technology, specifically relating to the application of pyrene-containing fluorescent probes in the detection of straight-chain fatty alcohols. Background Technology

[0002] Linear fatty alcohols (such as methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol) are commonly used organic solvents and synthetic raw materials in laboratories and chemical production. Linear fatty alcohol solvents are highly volatile, toxic, flammable, and prone to forming carcinogenic compounds, posing numerous potential hazards to life, health, environmental protection, and production and daily life safety. Furthermore, these compounds share similar physicochemical properties, making them prone to misuse and misapplication. Therefore, the detection and identification of linear fatty alcohols during production, storage, transportation, and use are particularly important. However, because these compounds are homologous, their physicochemical properties are very similar (e.g., polarity, acidity / basicity, reducing properties), and they lack photoelectric activity, highly sensitive detection and visual differentiation have always been a challenging and important issue.

[0003] For the detection of straight-chain fatty alcohols, commonly used techniques include gas chromatography, liquid chromatography, nuclear magnetic resonance, and high-resolution mass spectrometry. While these techniques offer advantages such as high selectivity and reliability, their cumbersome operation, high cost, time consumption, low sensitivity, and lack of visualization hinder their widespread adoption. Therefore, developing a visualization-based detection method that is highly sensitive, has good discrimination, fast response, broad applicability, does not corrode samples, and is not limited by physical space is of great significance.

[0004] Fluorescence sensing technology boasts advantages such as simple operation, high sensitivity, strong sample adaptability, non-abrasiveness, fast response, and ease of instrumentation, making it a widely used detection technique. However, there are few reports on fluorescence sensing techniques for straight-chain fatty alcohols. Furthermore, traditional polarity-dependent fluorescent probes are mostly rigid, prone to aggregation-induced fluorescence quenching, have complex molecular synthesis, produce single luminescent signals, have poor adjustability, and lack the ability to visually distinguish and identify similar compounds within a certain polarity range, thus limiting their practical applications. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide the application of pyrene-containing fluorescent probes in the detection of straight-chain fatty alcohols, so as to solve the problems of low sensitivity, inability to visualize detection, aggregation fluorescence quenching, poor controllability, and poor ability to distinguish and identify similar compounds in existing methods for detecting straight-chain fatty alcohols.

[0006] This invention is achieved through the following technical solution: The first aspect of this invention discloses the application of a pyrene-containing fluorescent probe in the detection of straight-chain fatty alcohols, wherein the structural formula of the pyrene-containing fluorescent probe is shown in formula (1):

[0007] Where R is hydrogen or iodine.

[0008] Preferably, the straight-chain fatty alcohol compound includes any one or more of methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol.

[0009] Preferably, the detection is the detection of straight-chain fatty alcohol compounds used as organic solvents or synthetic raw materials.

[0010] Preferably, the pyrene-containing fluorescent probe is a dual-emission fluorescent probe.

[0011] A second aspect of the present invention discloses a method for visually distinguishing linear fatty alcohol compounds. A mixture of a pyrene-containing fluorescent probe and a linear fatty alcohol compound is irradiated with ultraviolet light, and the types of linear fatty alcohol compounds are distinguished based on the difference in fluorescence color emitted by the pyrene-containing fluorescent probe solution. The structural formula of the pyrene-containing fluorescent probe is shown in formula (1).

[0012] Where R is hydrogen or iodine.

[0013] Preferably, ultraviolet light with a wavelength of 365 nm is used for irradiation.

[0014] A third aspect of the present invention discloses a method for distinguishing types of straight-chain fatty alcohols. A fluorescence emission spectrum of a mixture containing a pyrene fluorescent probe and a straight-chain fatty alcohol is performed to obtain two characteristic maximum emission wavelengths and their corresponding fluorescence emission intensities. The type of straight-chain fatty alcohol is distinguished based on the ratio of the two fluorescence emission intensities. The structural formula of the pyrene fluorescent probe is shown in formula (1).

[0015] Where R is hydrogen or iodine.

[0016] Preferably, the two fluorescence emission peaks are at 550 nm and 440 nm, respectively.

[0017] A fourth aspect of the present invention discloses a dedicated detection device for straight-chain fatty alcohol compounds, comprising a pyrene-containing fluorescent probe with the structure shown in formula (1):

[0018] Where R is hydrogen or iodine.

[0019] Preferably, it also includes a detection cavity, an excitation light source, and a fluorescence receiving module.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The application of the pyrene-containing fluorescent probe provided by this invention in the detection of straight-chain fatty alcohols utilizes a structure formed by introducing a pyrene structural fragment with strong π-π interactions, using a phenolic hydroxyl group (OH) as the proton donor and a moderately basic imine N atom as the proton acceptor. First, the proton of the phenolic hydroxyl group is transferred to the proton acceptor imine N atom in the excited state, resulting in two proton transfer isomers that can maintain mutual equilibrium and emit dual fluorescence. Simultaneously, the pyrene-containing fluorescent probe molecule in the excited state can also undergo C=N double bond rotational motion, competing with the excited-state proton transfer process, quenching the fluorescence emitted at short wavelengths. Furthermore, the potential barrier of the C=N double bond rotational motion is somewhat dependent on solvent polarity. Therefore, the ratio of fluorescence emission intensities at two different wavelengths can be controlled by changing the type of solvent with different polarities or adjusting the degree of molecular aggregation. This allows for the detection and identification of different solvents based on the ratio of fluorescence emission intensities at two different wavelengths, achieving ratiometric sensing. Furthermore, the fluorescence emission of this pyrene-containing fluorescent probe is solvent-dependent, exhibiting different fluorescence colors in solvents with slight polarity differences, thus enabling the visual detection of solvents (such as straight-chain fatty alcohols). Secondly, the introduction of the pyrene structure effectively suppresses the C=C double bond rotation of proton transfer products and fluorescence quenching at longer wavelengths, enhancing fluorescence emission. This provides a stable reference signal, improving the sensitivity of solvent detection and the ability to distinguish between structurally similar solvents. This pyrene-containing fluorescent probe exhibits tunable dual fluorescence emission signals. Its fluorescence emission is extremely sensitive to the solvent environment and shows obvious aggregation-dependent characteristics. It has low requirements for equipment and testing environment, and a fast response speed. It can be used to distinguish between different types of straight-chain fatty alcohols. By adding the pyrene-containing fluorescent compound as a probe molecule to a straight-chain fatty alcohol and using light of an appropriate wavelength as excitation light, ratiometric dual fluorescence emission dependent on the carbon chain length of the straight-chain fatty alcohol can be generated. It has ratiometric response capability to structurally similar straight-chain fatty alcohol homologues such as methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol. It can perform visual detection of straight-chain fatty alcohols, effectively solving the problem of visual detection of straight-chain fatty alcohol homologues that lack photoelectric activity and have similar structures and properties. With further development, it can be developed into a portable dedicated detection device for straight-chain fatty alcohols. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The hydrogen NMR spectrum of compound 1 obtained in this invention; Figure 2 This is a high-resolution mass spectrum of compound 1 obtained in this invention; Figure 3 The 1H NMR spectrum of compound 2 obtained in this invention; Figure 4 This is a high-resolution mass spectrum of compound 2 obtained in this invention; Figure 5 The absorption and excitation-emission spectra of compound 1 obtained in this invention in solution are shown. Figure 6 This is a potential energy profile of the ground state (S0) and the first excited state (S1) of compound 1 obtained in this invention along the proton transfer coordinate. Figure 7 This is a potential energy profile of the first excited state (S1) of the proton transfer product of compound 1 obtained in this invention, along the torsional coordinate change of the C=N double bond corresponding to the C=N rotational motion. Figure 8 This is a potential energy profile of the ground state and the first excited state (S1) of the proton transfer product of compound 1 obtained in this invention, showing the change in coordinates along the rotational motion of the C=C double bond. Figure 9 The fluorescence emission spectrum of compound 1 obtained in this invention in carbon tetrachloride and ethanol; Figure 10 The fluorescence emission spectrum of compound 1 in a mixed solvent of water (poor solvent) and ethanol (good solvent) as the volume of water and ethanol changes when 380 nm wavelength light is used as the excitation light in this invention. Figure 11 The fluorescence emission spectra of compound 1 obtained in this invention in methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol are shown. Figure 12 The image shows the fluorescence of compound 1 obtained in this invention under 365 nm ultraviolet light irradiation in methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0025] In this article, "room temperature" refers to a temperature of approximately 20°C to 35°C, or approximately 23°C to 28°C, or approximately 25°C. It can be 20°C, 25°C, 30°C, or 33°C.

[0026] The pyrene-containing fluorescent probe provided by this invention is a dual-emission excited-state intramolecular proton transfer fluorescent probe based on the rotational motion of the C=N double bond and with tunable luminescence, and its structural formula is shown in formula (1):

[0027] Wherein, R is hydrogen or iodine; specifically, the pyrene-containing fluorescent probe is compound 1 or compound 2 as shown below: .

[0028] The pyrene-containing fluorescent probe of formula (1) of this invention uses a phenolic hydroxyl group as a proton donor and a moderately basic imine N atom as a proton acceptor, and introduces a pyrene structural fragment with strong π-π interactions. In the excited state, the phenolic hydroxyl group can transfer a proton to a proton acceptor with appropriate acidity and basicity, generating two proton transfer isomers that can maintain a certain equilibrium and emit dual fluorescence. The maximum emission positions of the two fluorescence emission bands are located at 440 nm and 545 nm, respectively. That is, the compound of formula (1) of this invention is a dual-emission fluorescent probe. The fluorescence emission intensity of the pyrene-containing fluorescent probe in different solvents and the relative fluorescence emission intensity at the two maximum fluorescence emission wavelengths are different. Therefore, different solvents can be detected and identified based on the ratio of the fluorescence emission intensities at the two different wavelengths, realizing ratiometric sensing. Simultaneously, the fluorescence color of the pyrene-containing fluorescent probe differs in different solvents with slight polarity differences, which can be used for the visual detection of solvents with slight polarity differences. Meanwhile, the introduction of pyrene structural units expands the degree of molecular conjugation, stabilizes the fluorescent molecular structure, and can effectively suppress the C=C double bond rotation of proton transfer products, avoiding fluorescence quenching. This results in stable fluorescence emission signals of proton transfer products at long wavelengths, which can be used as a reference signal to facilitate the construction of a ratiometric fluorescence sensing platform, thereby improving the sensitivity and distinguishability of solvent detection.

[0029] The pyrene-containing fluorescent probe has two absorption bands, with maximum absorption positions at 290 nm and 380 nm, respectively, where 380 nm is the maximum excitation wavelength (Ex). When the pyrene-containing fluorescent probe is excited to the excited state, and relaxes to the local minimum stable point of the first excited state, the C=N double bond rotation process that quenches fluorescence competes with the intramolecular proton transfer process that generates two fluorescent emitting species, thus endowing the pyrene-containing fluorescent probe molecule with tunable dual fluorescence emission properties. Since the potential barrier of the C=N double bond rotation is dependent on the solvent polarity, its dual fluorescence emission behavior can be modulated by changing the solvent type or the degree of aggregation of fluorescent molecules.

[0030] Specifically, when the pyrene-containing fluorescent probe is excited with 380 nm light, dual fluorescence originating from two excited-state proton transfer isomers is generated at maximum emission locations of 440 nm and 545 nm. The absolute and relative fluorescence intensities of these two sets of emissions exhibit a certain dependence on the polarity of the solvent used. Therefore, the luminescence behavior of the pyrene-containing fluorescent probe can be controlled by changing the type of solvent. Furthermore, when a poor solvent is introduced into a good solvent, the aggregation of molecules restricts their C=N rotational motion, causing the fluorescence emission at 440 nm to gradually increase with the increase of the poor solvent content, while the fluorescence emission at 545 nm remains essentially unchanged. Therefore, the fluorescence emission behavior can also be adjusted by regulating the degree of aggregation of the pyrene-containing fluorescent probe molecules. In other words, the luminescence behavior of the pyrene-containing fluorescent probe of this invention can be controlled. Specifically, the luminescence behavior can be controlled by changing the type of solvent used to dissolve the pyrene-containing fluorescent probe, or by changing the degree of aggregation of the pyrene-containing fluorescent probe.

[0031] The synthesis method of the above-mentioned pyrene-containing fluorescent probe provided by the present invention involves reacting 1-aminopyrene with salicylaldehyde (or 4-iodosalicylic acid) under argon protection by heating to obtain the pyrene-containing fluorescent probe shown in formula (1).

[0032] In some preferred embodiments of the present invention, the molar ratio of 1-aminopyrene to salicylaldehyde (or 4-iodosalicylic acid) is 1:(1~1.1).

[0033] In some preferred embodiments of the present invention, the temperature of the heating reaction is 120~160°C, and the reaction time is 4~8 hours.

[0034] Specifically, in some embodiments of the present invention, 1-aminopyrene is mixed with salicylaldehyde (or 4-iodosalicylaldehyde) and then anhydrous ethanol is added. The reaction is carried out under an inert atmosphere. After the reaction is completed, the reaction solution is cooled to room temperature, filtered, and a crude product is obtained. Then, column chromatography is performed to obtain the pyrene-containing fluorescent probe shown in formula (1).

[0035] In this invention, the 1-aminopyrene reacts with salicylaldehyde (or 4-iodosalicylaldehyde) under an inert atmosphere to avoid side reactions caused by the presence of oxygen in the air.

[0036] In this invention, anhydrous ethanol is used as a solvent. Its high boiling point ensures that the preparation of the compound can be carried out at a high temperature. At the same time, the pyrene-containing fluorescent probe product has very low solubility in anhydrous ethanol, which facilitates product separation and purification. The molar ratio of 1-aminopyrene to anhydrous ethanol is 1:(150~550).

[0037] In this invention, column chromatography separation uses a petroleum ether-dichloromethane system as the eluent, wherein the volume ratio of petroleum ether to dichloromethane is preferably 1:(1~3).

[0038] In this invention, recrystallization is performed using a mixed solvent of dichloromethane and n-hexane, with the preferred volume ratio of dichloromethane to n-hexane being (2~3):1.

[0039] Based on the tunable nature of the dual fluorescence emission behavior of the pyrene-containing fluorescent probe described in this invention, the luminescence behavior of the pyrene-containing fluorescent probe differs in different types of straight-chain fatty alcohol solvents. Specifically, the fluorescence color emitted by the pyrene-containing fluorescent probe differs in different types of straight-chain fatty alcohol compounds, and the relative fluorescence emission intensity at the two maximum fluorescence emission wavelengths differs. Therefore, the pyrene-containing fluorescent probe described in this invention can be used for visual detection of straight-chain fatty alcohol compounds, distinguishing different types of straight-chain fatty alcohol compounds, such as methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol.

[0040] Specifically, the application of the pyrene-containing fluorescent probe of the present invention in the detection of straight-chain fatty alcohols includes: adding the pyrene-containing fluorescent probe to a straight-chain fatty alcohol to obtain a pyrene-containing fluorescent probe solution; irradiating the pyrene-containing fluorescent probe solution with ultraviolet light, and identifying the type of straight-chain fatty alcohol based on the difference in fluorescence color emitted by the pyrene-containing fluorescent probe solution; wherein the concentration of the pyrene-containing fluorescent probe solution is 0.005~0.1 mmol / L.

[0041] To further improve the accuracy of the detection results, further detection can be performed: the pyrene-containing fluorescent probe is added to a straight-chain fatty alcohol compound to obtain a pyrene-containing fluorescent probe solution; the fluorescence emission spectrum of the pyrene-containing fluorescent probe solution is tested to obtain the first fluorescence emission intensity corresponding to the first maximum emission wavelength (440 nm) and the second fluorescence emission intensity corresponding to the second maximum emission wavelength (550 nm); the type of straight-chain fatty alcohol compound is identified based on the ratio of the second fluorescence emission intensity to the first fluorescence emission intensity.

[0042] Of course, the type of straight-chain fatty alcohol compound can also be identified directly based on the ratio of the second fluorescence emission intensity to the first fluorescence emission intensity.

[0043] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading this description, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0044] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications in the art, unless otherwise stated.

[0045] I. Preparation of Pyrene-containing fluorescent probes Example 1 Preparation of pyrene-containing fluorescent probe (compound 1)

[0046] 0.49 g (0.002 mol) of 1-aminopyrene and 0.25 g (0.002 mol) of salicylaldehyde were placed in a 100 mL Shrek flask. Anhydrous ethanol (30 mL, 0.514 mol) was added to the Shrek flask. Under argon protection, the reaction system was stirred and heated to 140 °C and refluxed for 4 hours. The resulting reaction mixture was cooled to room temperature and filtered. The crude solid product was separated by column chromatography using petroleum ether-dichloromethane (volume ratio of petroleum ether to dichloromethane 1:2) as the eluent. The collected fraction was evaporated to dryness to obtain a yellow solid. This solid was then recrystallized from dichloromethane-n-hexane (volume ratio of dichloromethane to n-hexane 2:1) to obtain a pyrene-containing fluorescent probe (compound 1), which was a yellow crystal with a yield of 70%. The 1H NMR spectrum and high-resolution mass spectrum of compound 1 prepared in this example are shown below. Figure 1 and Figure 2 As shown.

[0047] Example 2 Preparation of pyrene-containing fluorescent probe (compound 2)

[0048] 1-Aminopyrene (0.25 g, 0.001 mol) and 4-iodosalicylic acid (0.29 g, 0.001 mol) were placed in a 100 mL Shrek flask. Anhydrous ethanol (30 mL, 0.514 mol) was added to the Shrek flask. Under argon protection, the reaction system was stirred and heated to 160 °C, and refluxed for 8 hours. The resulting reaction mixture was cooled to room temperature and filtered. The obtained crude solid was separated by column chromatography using petroleum ether-dichloromethane (volume ratio of petroleum ether to dichloromethane 1:2) as the eluent. The collected fraction was evaporated to dryness to obtain a yellow solid. This solid was then recrystallized from dichloromethane-n-hexane (volume ratio of dichloromethane to n-hexane 2:1) to obtain a pyrene-containing fluorescent probe (compound 2), which was an orange solid with a yield of 60%. The 1H NMR spectrum and high-resolution mass spectrum of compound 2 prepared in this example are shown below. Figure 3 and Figure 4 As shown.

[0049] II. Performance Study of Pyrene-Containing Fluorescent Probes 1. Preparation of pyrene-containing fluorescent probe solution The preparation of a pyrene-containing fluorescent probe solution using compound 1 obtained in Example 1 includes the following steps: 1) Prepare a solution of compound 1 with a concentration of 0.01 mmol / L using a solvent, seal it, and let it stand for 10-15 minutes for later use; 2) Filter the solution obtained in step 1) using an organic microporous membrane with a pore size of 0.22 μm. After freezing the filtrate with liquid nitrogen, immerse it in acetone at room temperature for 3 minutes. After the solution temperature returns to room temperature, repeat this hot and cold cycle three times to remove the gas in the solution and obtain the pyrene fluorescent probe solution. Seal and store it for later use.

[0050] 2. Performance Study of Pyrene-Containing Fluorescent Probes To verify the effectiveness of the pyrene-containing fluorescent probe, the pyrene-containing fluorescent probe solution obtained in step 1 was subjected to the following experiments: 1) Basic photophysical behavior characterization experiments The absorption and excitation-emission spectra of the pyrene-containing fluorescent probe solution obtained in step 1 were characterized using a T2602S dual-beam UV-Vis spectrophotometer from Shanghai Youke Instrument Co., Ltd. and a Hitachi F-7100 fluorescence spectrometer.

[0051] The results are as follows Figure 5 As shown, compound 1 has two absorption bands, with maximum absorption positions at 290 nm and 380 nm, respectively, where 380 nm is the maximum excitation wavelength (Ex). Under 380 nm light excitation, compound 1 exhibits two fluorescence emission bands, with maximum emission positions at 440 nm and 545 nm, respectively, indicating that compound 1 is a dual-emission fluorescent probe. This result provides light source and detection wavelength information for the identification of linear fatty alcohols. Based on this result, this invention selects a 380 nm light source as the excitation source and detects the fluorescence emission intensity at 440 nm and 545 nm (or 550 nm) for subsequent detection experiments of linear fatty alcohols.

[0052] 2) Calculation of excited-state processes of compound 1 This experiment comprehensively explored the luminescence mechanism and fluorescence emission regulation mechanism of pyrene-containing fluorescent probes to guide their practical applications. In this experiment, time-dependent density functional theory was used. At the (TD-)PBE0 / 6-31G(d) level (time-dependent density functional theory calculations were performed using the PBE0 functional and the 6-31G(d) basis set), a continuous polarized solvent model was employed to simulate the ground and excited state potential energy profiles of compound 1 along the proton transfer coordinates, the C=N double bond torsional coordinates, and the proton transfer products along the C=C double bond rotational motion coordinates.

[0053] The calculation results are as follows Figures 6-8 As shown, by Figure 6 It is known that compound 1 has two stable proton transfer isomers in the S1 state. When compound 1 is vertically excited to the first excited state (FC region), it relaxes to the first local minimum, denoted as S1-min-N (emitting 440 nm fluorescence). Subsequently, after overcoming the 4.3 kcal / mol barrier in the S1 state, a proton transfer product is generated, denoted as S1-min-T (emitting 545 nm fluorescence). The barrier for the reverse reaction is 5.0 kcal / mol. The barriers for the forward and reverse reactions are not significantly different, allowing the two proton transfer isomers to exist stably and return to the ground state through the radiation channel, emitting 440 nm and 545 nm fluorescence, respectively. This lays a solid foundation for ratiometric dual-emission fluorescent probes that can detect and identify different solvents based on a single chromophore framework structure. Figure 7 It is known that when compound 1 is excited to the S1 state, in addition to intramolecular proton transfer, a C=N rotational motion competing with the proton transfer reaction also exists, quenching the fluorescence of the pyrene-containing fluorescent probe. Furthermore, the barrier to this C=N rotational motion is somewhat dependent on the polarity of the solvent. For example, in nonpolar carbon tetrachloride, this rotational motion is barrier-free, while in the polar solvent ethanol, the barrier is 0.8 kcal / mol. This sensitivity to the environment and its state provides a solid foundation for controlling the luminescence behavior of the pyrene-containing fluorescent probe by changing the solvent type and adjusting the degree of molecular aggregation. Figure 8 It is known that the C=C double bond rotation of the proton transfer product of compound 1 needs to overcome a potential barrier of 6.2 kcal / mol to generate a stable configuration in which the proton donor and acceptor are perpendicular to each other and lose fluorescence activity. In other words, this large reaction barrier inhibits the fluorescence inactivation of the proton transfer product, making its planar configuration relatively stable and emitting a stable fluorescence signal at 545 nm. This lays a solid foundation for the construction of a ratiometric fluorescence sensing platform based on compound 1.

[0054] 3) Light emission behavior regulation experiment Using a Hitachi UH5300 dual-beam UV-Vis spectrophotometer, under room temperature and light-protected conditions, a 1 cm quartz cuvette was used. The excitation wavelength was 380 nm, and both the excitation and emission slits were 5 nm. The scanning speed was 240 nm / min. Fluorescence emission spectra from 400 to 750 nm were collected. The solvent-dependent fluorescence spectra of the pyrene-containing fluorescent probe solution obtained in step 1 in ethanol and carbon tetrachloride, as well as the aggregation-dependent fluorescence emission spectra of ethanol with different water contents, were measured. The intensity of the characteristic emission peak at 440 nm and the relative intensity of the dual fluorescence were recorded.

[0055] The results are as follows Figure 9 and Figure 10 As shown. By Figure 9 It is known that when the pyrene-containing fluorescent probe solution is excited by 380 nm light, the potential barrier of the C=N double bond rotation is dependent on solvent polarity. This results in a significantly greater contribution of fluorescence emission originating at 440 nm in ethanol to the fluorescence spectrum compared to fluorescence emission in carbon tetrachloride. Therefore, the luminescence behavior of the pyrene-containing fluorescent probe can be modulated by changing the solvent type. This method is simple to operate, not limited by time or space, and the sample can be recovered and reused. Figure 10 It is known that as the water content in ethanol increases, fluorescent molecules continuously aggregate, resulting in the fluorescence emission intensity of compound 1 at 440 nm and the relative intensity of the two sets of fluorescence emission being dependent on the water content in the solvent ethanol. Therefore, the dual fluorescence emission behavior of pyrene-containing fluorescent probes can be modulated by adjusting the degree of aggregation of fluorescent molecules. This method is simple to operate, not limited by time and space, and the sample can be recovered. Based on the novel fluorescence emission regulation mechanism of proton transfer molecules containing C=N double bonds, it can provide a new idea for the regulation of the luminescence behavior of such pyrene-containing fluorescent probe molecules.

[0056] III. Application of Pyrene-containing fluorescent probes in the detection of straight-chain fatty alcohols 1. Fluorescence emission spectroscopy test Following the preparation method of the pyrene-containing fluorescent probe solution in step 2.1, different types of straight-chain fatty alcohol compounds (methanol (CH3OH), ethanol (CH3CH2OH), n-propanol (CH3(CH2)2OH), n-butanol (CH3(CH2)3OH), n-pentanol (CH3(CH2)4OH), n-hexanol (CH3(CH2)5OH)) were used to prepare pyrene-containing fluorescent probe solutions with methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol as solvents, respectively. Fluorescence emission spectroscopy experiments were conducted using a Hitachi F-7100 fluorescence spectrometer.

[0057] The results are as follows Figure 11 As shown, in different straight-chain fatty alcohol solvents, with increasing solvent carbon chain length, the contribution of fluorescence emission at 550 nm to the fluorescence spectrum gradually increases when using 380 nm wavelength light as excitation light. Dividing the fluorescence emission intensity at 550 nm by the fluorescence emission intensity at 440 nm yields I. 550 / I 440 The values ​​are shown in Table 1. Table 1 shows that for different straight-chain fatty alcohol solvents, the obtained I... 550 / I 440 The values ​​differ, according to I 550 / I 440The difference in values ​​can distinguish between methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol.

[0058] Table 1. I of different straight-chain fatty alcohol solvents 550 / I 440 Value detection results

[0059] 2. Ultraviolet lamp irradiation experiment Following the preparation method of the pyrene-containing fluorescent probe solution in step 2.1, different types of straight-chain fatty alcohol compounds (methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol) were used to prepare pyrene-containing fluorescent probe solutions with methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol as solvents. Then, they were placed in quartz cuvettes and irradiated with a 365 nm ultraviolet lamp at room temperature and in the dark, and the fluorescence luminescence of each solution under ultraviolet lamp irradiation was photographed.

[0060] The results are as follows Figure 12 As shown, six pyrene-containing fluorescent probe solutions in methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol exhibit different fluorescence colors, enabling visual detection of methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol. This method is simple, inexpensive, rapid, and allows for immediate detection. The probe molecules can be recovered and reused, making it a novel ratiometric fluorescence visualization detection method based on pyrene-containing fluorescent probes.

[0061] In summary, this invention utilizes a phenolic hydroxyl group as a proton donor and a moderately basic imine N atom as a proton acceptor, introducing a pyrene structural fragment with strong π-π interactions to enhance the conjugation of the proton transfer product of the pyrene-containing fluorescent probe and suppress the fluorescence inactivation motion of the C=C double bond rotation in the proton transfer product. By balancing the intramolecular proton transfer reaction and C=N double bond rotation of the excited-state pyrene-containing fluorescent molecule, a dual-emission fluorescent probe with an excited-state intramolecular proton transfer reaction is developed. A novel fluorescence emission regulation mechanism for excited-state proton transfer molecules containing C=N double bonds is proposed, using a method to regulate the luminescence behavior by changing the solvent type and adjusting the aggregation degree of the pyrene-containing fluorescent probe. This method is simple to operate, does not corrode or contact the sample, is not limited by physical space, and the probe molecules can be recovered and reused. Simultaneously, the invention achieves visualized detection of methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol, developing a new method for the visualized detection of straight-chain fatty alcohols.

[0062] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. Use of a pyrene-containing fluorescent probe for the detection of straight-chain aliphatic alcohols, characterized in that, The structure of the pyrene-containing fluorescent probe is shown in formula (1): Where R is hydrogen or iodine.

2. The use of the pyrene-containing fluorescent probe according to claim 1 in the detection of straight-chain fatty alcohol compounds, characterized in that, The straight-chain fatty alcohols include any one or more of methanol, ethanol, n-propanol, n-butanol, n-pentanol, and n-hexanol.

3. The application of the pyrene-containing fluorescent probe according to claim 1 in the detection of straight-chain fatty alcohols, characterized in that, The detection refers to the detection of straight-chain fatty alcohol compounds used as organic solvents or synthetic raw materials.

4. The application of the pyrene-containing fluorescent probe according to claim 1 in the detection of straight-chain fatty alcohols, characterized in that, The pyrene-containing fluorescent probe is a dual-emission fluorescent probe.

5. A method for visually distinguishing straight-chain fatty alcohols, characterized in that, The mixture of pyrene-containing fluorescent probe and straight-chain fatty alcohol compound was irradiated with ultraviolet light, and the types of straight-chain fatty alcohol compound were distinguished based on the difference in fluorescence color emitted by the pyrene-containing fluorescent probe solution; the structural formula of the pyrene-containing fluorescent probe is shown in formula (1): Where R is hydrogen or iodine.

6. The method for visually distinguishing straight-chain fatty alcohols according to claim 5, characterized in that, Irradiation was performed using ultraviolet light with a wavelength of 365 nm.

7. A method for distinguishing types of straight-chain fatty alcohols, characterized in that, Fluorescence emission spectroscopy was performed on a mixture of a pyrene-containing fluorescent probe and a straight-chain fatty alcohol compound to obtain two characteristic maximum emission wavelengths and their corresponding fluorescence emission intensities. The type of straight-chain fatty alcohol compound was distinguished based on the ratio of the two fluorescence emission intensities. The structural formula of the pyrene-containing fluorescent probe is shown in formula (1). Where R is hydrogen or iodine.

8. A method for distinguishing types of straight-chain fatty alcohols according to claim 7, characterized in that, The two fluorescence emission peaks are at 550 nm and 440 nm, respectively.

9. A dedicated detection device for straight-chain fatty alcohols, characterized in that, Contains a pyrene-containing fluorescent probe with the structure shown in formula (1): Where R is hydrogen or iodine.

10. A dedicated detection device for straight-chain fatty alcohols according to claim 9, characterized in that, It also includes a detection chamber, an excitation light source, and a fluorescence receiving module.

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