Preparation method and application of difunctional fluorescent self-assembly gel

Abstract

The invention relates to the technical field of fluorescence analysis, and discloses a preparation method and application of difunctional fluorescent self-assembly gel, and the preparation method comprises the following steps: reacting 6-(dimethylamino)-2-naphthaldehyde with N-(2-(2-cyano propionamido) ethyl)-3, 4, 5-tri (dodecyl) benzamide in the presence of a catalyst, and purifying to obtain an alpha-cyano styrene derivative; the derivative is dissolved in an organic solvent, and the difunctional fluorescent self-assembly gel is obtained through the processes of heating dissolution and cooling self-assembly. High-selectivity and high-sensitivity detection on the hypochlorite ions is realized based on the oxidative damage effect of the hypochlorite ions on carbon-carbon double bonds in derivative molecules; based on the solvation effect of the derivative in different polar solvent environments, the detection of methanol, ethanol and other short-chain fatty alcohols is realized. The preparation method is simple, and the obtained gel is single in structure, has two different detection functions and is clear in application scene.

Description

Technical Field

[0001] This invention relates to the field of fluorescence analysis technology, specifically to a method for preparing bifunctional fluorescent self-assembled gels and their applications. Background Technology

[0002] Fluorescent materials have gained widespread attention and application in fields such as chemistry, biology, and environmental monitoring due to their high sensitivity, rapid response, and ease of operation. Among them, chemical sensors based on fluorescence principles provide an effective means for the identification and detection of specific target molecules in analytical science.

[0003] However, existing fluorescence sensors still face some technical challenges in practical applications. For example, in the detection of short-chain fatty alcohols, some fluorescent probes exhibit indistinct spectral responses or limited response ranges in different solvent environments, making it difficult to distinguish and quantify different types of short-chain fatty alcohols. Furthermore, in complex sample matrices, existing detection methods are affected by interference from other coexisting substances, impacting the accuracy and selectivity of the detection.

[0004] Furthermore, hypochlorite ions, as an important reactive oxygen species, play a crucial role in biological processes, water treatment, and disinfection. Their accurate detection is essential for environmental monitoring and health safety. Currently, fluorescent probes used for hypochlorite ion detection still have room for improvement in selectivity. Some probes exhibit cross-interference when encountering other anions or reactive oxygen species, leading to misinterpretations. Additionally, some existing probes require long response times or lack sufficient sensitivity at low concentrations, limiting their application in rapid detection and trace analysis.

[0005] Furthermore, most existing fluorescent materials are typically designed for single targets. Achieving multifunctional detection often requires the fabrication of multiple different probes or the construction of complex composite systems. This not only increases fabrication costs and operational complexity but also limits the integration and application range of the materials. Although some self-assembled systems exhibit tunable spectral properties, developing a material that can form a stable gel through a simple self-assembly process and simultaneously possesses specific fluorescence responses to different types of analytes (such as polar organic molecules and oxidizing inorganic ions) remains a technological requirement in current research. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing bifunctional fluorescent self-assembled gels and their applications, solving the problems of insufficient selective detection capability for hypochlorite ions and unclear response for distinguishing short-chain fatty alcohols in existing technologies.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing bifunctional fluorescent self-assembled gels and their applications.

[0008] The first aspect of this invention provides a method for preparing a bifunctional fluorescent self-assembled gel, the method comprising the following steps:

[0009] Synthesis of S1, α-cyanostyrene derivatives: 6-(dimethylamino)-2-naphthal and N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide were mixed in anhydrous ethanol solvent with piperidine as a catalyst. The mixture was then reacted under reflux conditions.

[0010] In one specific embodiment, the molar ratio of 6-(dimethylamino)-2-naphthaldehyde to N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide is 1:(0.9-1.2). The duration of the reflux reaction can be set to 10-14 hours.

[0011] After the reaction is completed, the reaction product is purified to obtain the target product, namely, the α-cyanostyrene derivative. The purification process specifically includes: firstly, removing the anhydrous ethanol solvent by vacuum distillation to obtain the crude product; and then separating and purifying the crude product by column chromatography.

[0012] S2. Preparation of the bifunctional fluorescent self-assembled gel: The α-cyanostyl styrene derivative obtained in step S1 is dissolved in an organic solvent, and the system is heated until the α-cyanostyl styrene derivative is completely dissolved to form a homogeneous solution. Subsequently, the solution is cooled to room temperature. During the cooling process, the α-cyanostyl styrene derivative molecules self-assemble to form a three-dimensional network structure, thereby obtaining the bifunctional fluorescent self-assembled gel.

[0013] The organic solvent may be selected from at least one of the following: n-hexane, acetone, methanol, tetrahydrofuran, ethyl acetate, ethanol, acetonitrile, toluene, N,N-dimethylformamide / water, dimethyl sulfoxide, 1,4-dioxane, 1,2-dichlorobenzene, or 1,3,5-trimethylbenzene.

[0014] When the organic solvent is n-hexane, the concentration of the α-cyanostyrene derivative in the n-hexane can be set to 2.0-2.5 mg / mL.

[0015] When the organic solvent is a mixed solvent of N,N-dimethylformamide and water in a volume ratio of 4:1, the concentration of the α-cyanostyrene derivative in the mixed solvent can be set to 19.0-21.0 mg / mL.

[0016] A second aspect of the present invention provides the application of the bifunctional fluorescent self-assembly gel.

[0017] The application is to use the bifunctional fluorescent self-assembled gel or its precursor (i.e., the solution of the α-cyanostyrene derivative) obtained by the preparation method described in the first aspect of the present invention for the detection of specific substances.

[0018] 1. Application in the selective detection of hypochlorite ions: The technical mechanism of this application lies in the presence of carbon-carbon double bonds in the molecular structure of the α-cyanostyrene derivative. When hypochlorite ions are present in the system, these carbon-carbon double bonds are oxidized and destroyed by the hypochlorite ions. This structural destruction blocks the intramolecular charge transfer process, which is directly manifested in the quenching of the fluorescence emission spectrum of the derivative. Therefore, by monitoring the change in fluorescence intensity of the α-cyanostyrene derivative, highly selective and sensitive detection of hypochlorite ions can be achieved.

[0019] 2. Application in the detection of short-chain fatty alcohols: The technical mechanism of this application lies in the significant differences in the luminescent properties of the α-cyanostyl styrene derivative under different solvent environments. When placed in a system containing short-chain fatty alcohols (e.g., methanol, ethanol), the solvent environment changes, causing a measurable change in its fluorescence emission spectrum. Therefore, the short-chain fatty alcohols can be detected by analyzing the changes in the fluorescence emission spectrum. This detection capability decreases with increasing alkyl chain length in the alcohol compound.

[0020] This invention provides a method for preparing bifunctional fluorescent self-assembled gels and their applications. It offers the following advantages:

[0021] 1. This invention provides a fluorescent material with a single structure and dual core function. By designing the molecular structure of an α-cyanostrene derivative, it simultaneously possesses two independent response mechanisms: one is based on the specific oxidation reaction between the intramolecular carbon-carbon double bond and hypochlorite ions, and the other is based on the intramolecular charge transfer (ICT) characteristic in response to changes in solvent polarity. This allows a single compound to separately detect inorganic oxidizing ions and polar organic small molecules, overcoming the limitations of existing technologies that typically require multiple materials or complex systems to achieve multi-target detection.

[0022] 2. This invention achieves highly selective and sensitive detection of hypochlorite ions. Its detection mechanism is based on the irreversible chemical disruption of the key conjugated system (carbon-carbon double bond) in the derivative molecule by the hypochlorite ion. This reaction is highly specific; other common anions do not react under the same conditions, thus avoiding cross-interference. Simultaneously, this chemical reaction leads to a significant change in the fluorescence signal, which is beneficial for achieving sensitive detection of low concentrations of hypochlorite ions, solving the problems of insufficient selectivity and limited sensitivity.

[0023] 3. This invention provides an effective detection scheme for short-chain fatty alcohols. Utilizing the solvation effect of the derivatives, when short-chain fatty alcohols such as methanol and ethanol are present in the system, the change in polarity of the solvent microenvironment causes a regular and measurable shift in their fluorescence emission spectra. This spectral response is clear, and the degree of response is related to the type and concentration of the alcohol, providing a technical basis for distinguishing and detecting different short-chain fatty alcohols, and overcoming the shortcomings of existing technologies that have unclear or indistinguishable responses to these substances. Attached Figure Description

[0024] Figure 1 The organogel compound of the α-cyanostylstyrene derivative of the present invention 1 HNMR spectrum;

[0025] Figure 2 The organogel compound of the α-cyanostylstyrene derivative of the present invention 13 CNMR spectrum;

[0026] Figure 3 The UV-Vis absorption spectra of the compound DNAE of this invention in solution and gel states are shown.

[0027] Figure 4 The fluorescence emission spectra of the compound DNAE of this invention in solution and gel states are shown.

[0028] Figure 5 The fluorescence emission spectrum and corresponding linear curve of methanol titration of hexane solution of the compound DNAE of the present invention are shown.

[0029] Figure 6 Fluorescence emission chromatograms and corresponding linear curves of hexane solutions of the compound DNAE of the present invention for titration with other short-chain fatty alcohols;

[0030] Figure 7 The fluorescence spectrum of the compound DNAE of this invention for the detection of ClO- is shown below.

[0031] Figure 8 This is a high-resolution mass spectrum of the reaction between the compound DNAE of this invention and ClO-. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments and comparative examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Examples 1-3:

[0034] Example 1: Preparation of α-cyanostylstyrene derivatives

[0035] This embodiment aims to specifically illustrate the preparation process of the core functional compound α-cyanostyrene derivative in this invention.

[0036] 2.13 g (10.0 mmol) of 6-(dimethylamino)-2-naphthal, 8.17 g (10.0 mmol) of N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide, 150 mL of anhydrous ethanol, and 0.5 mL of piperidine were added to a 250 mL round-bottom flask. The mixture was then stirred magnetically under reflux for 12 hours.

[0037] After the reaction was complete, the reaction solution was cooled to room temperature. Anhydrous ethanol was evaporated under reduced pressure using a rotary evaporator to obtain an orange-red oily crude product. This crude product was then purified by silica gel column chromatography (using dichloromethane / methanol as eluent, with a volume ratio gradient from 100:1 to 50:1). The target product fraction was collected, and the eluent was removed under reduced pressure, finally yielding 9.21 g of a yellow solid powder of α-cyanostyl styrene derivative, with a yield of 91%.

[0038] The chemical structure of the obtained product was confirmed by nuclear magnetic resonance spectroscopy. 1 HNMR spectrum as follows Figure 1 As shown, 13 CNMR spectrum as shown Figure 2 As shown, the spectral data is consistent with the structure of the target compound.

[0039] in, Figure 1 The meaning is as follows:

[0040] The horizontal axis (X-axis) represents the chemical shift, measured in ppm (parts per million). It characterizes the chemical environment of different hydrogen atoms in a molecule, with a higher value indicating a lower electron cloud density around the hydrogen atom.

[0041] The vertical axis (Y-axis) represents the signal intensity, reflecting the number of hydrogen atoms at the corresponding chemical shift. The higher the peak / the larger the area, the more hydrogen atoms there are.

[0042] Spectral peak information: Peaks at different positions in the graph correspond to hydrogen atoms of different groups in the DNAE molecule, for example:

[0043] δ8.31(s,1H): Single peak (s), corresponding to a specific hydrogen atom on the naphthalene ring;

[0044] δ3.13 (s, 6H): Single peak, corresponding to dimethylamino-N(CH3) 2) Methyl hydrogen;

[0045] δ0.87(m,9H): Multiple peaks (m), corresponding to the methyl hydrogen at the end of the long-chain alkyl (dodecyl) group.

[0046] Figure 2 The meaning is as follows:

[0047] The horizontal axis (X-axis) represents the chemical shift of carbon nuclei, measured in ppm. It characterizes the chemical environment of different carbon atoms in a molecule and typically ranges from 0 to 220 ppm (this figure mainly shows 0 to 180 ppm).

[0048] The vertical axis (Y-axis) represents the signal strength, reflecting the number of carbon atoms at the corresponding chemical shift.

[0049] Key peaks: Resonance signals corresponding to different carbons in the DNAE molecule, for example:

[0050] δ168.0, 163.3: Corresponding to the carbonyl carbon (C=O) of the amide bond (-CONH-);

[0051] δ153.3, 151.5: Corresponding to the double-bonded carbons on the naphthalene ring and the benzene ring;

[0052] δ41.4, 40.5: correspond to the methylene (-CH2-) carbon;

[0053] δ14.1: corresponds to the terminal methyl carbon (-CH) of the long-chain alkyl group. 3) .

[0054] Example 2: Preparation of bifunctional fluorescent self-assembled gel

[0055] This embodiment aims to illustrate the process of preparing α-cyanostyl styrene derivatives under lower parameter limits and using them to prepare gels in a hexane solvent system.

[0056] (1) The preparation of the α-cyanostyrene derivative was carried out according to the preparation method in Example 1, except that: the amount of N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide was 7.35 g (9.0 mmol), so that its molar ratio with 6-(dimethylamino)-2-naphthal was 1:0.9; and the duration of the reflux reaction was set to 10 hours. The target product was obtained after purification.

[0057] (2) Preparation of Bifunctional Fluorescent Self-Assembled Gel: Accurately weigh 10.0 mg of the α-cyanostyl styrene derivative obtained in step (1) and place it in a sealed sample vial. Add 5.0 mL of n-hexane to the vial, at which point the compound concentration is 2.0 mg / mL. Place the sample vial on a heating stage and heat until the solid completely dissolves to form a clear yellow solution. Remove the sample vial and allow it to cool at room temperature. After cooling, the solution transforms into a non-flowing, stable yellow self-supporting gel.

[0058] Example 3: Preparation of bifunctional fluorescent self-assembled gel

[0059] This embodiment aims to illustrate the process of preparing α-cyanostyl styrene derivatives under upper limit parameter conditions and using them to prepare gels in an N,N-dimethylformamide / water solvent system.

[0060] (1) The preparation of the α-cyanostyrene derivative was carried out according to the preparation method in Example 1, except that: the amount of N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide was 9.80 g (12.0 mmol), so that its molar ratio with 6-(dimethylamino)-2-naphthal was 1:1.2; and the duration of the reflux reaction was set to 14 hours. The target product was obtained after purification.

[0061] (2) Preparation of Bifunctional Fluorescent Self-Assembled Gel: Accurately weigh 100.0 mg of the α-cyanostyl styrene derivative obtained in step (1) and place it in a sealed sample vial. First, add 4.0 mL of N,N-dimethylformamide to the vial and shake to dissolve it. Then, add 1.0 mL of deionized water. At this point, the concentration of the compound in the mixed solvent is 20.0 mg / mL. Place the sample vial on a heating stage and heat until a homogeneous and clear solution is formed. Remove the sample vial and allow it to cool at room temperature. After cooling, the solution transforms into a non-flowing, stable, yellow self-supporting gel.

[0062] Comparative Examples 1-2:

[0063] Comparative Example 1:

[0064] The difference from Example 1 is that 0.5 mL of piperidine is not added in the feeding step, but all other steps are the same.

[0065] After the reaction was completed, the target product, α-cyanostyrene derivative, was not obtained upon testing.

[0066] Comparative Example 2:

[0067] Compared with Example 2, the difference is that in the preparation of the bifunctional fluorescent self-assembled gel, 5.0 mg of the α-cyanostyrene derivative obtained in step (1) was weighed and 5.0 mL of n-hexane was added to make the compound concentration 1.0 mg / mL, and the rest were the same.

[0068] After heating to dissolve and cooling to room temperature, the system failed to form a gel and remained in a solution state.

[0069] Test Example 1-3:

[0070] Test Example 1: Basic Spectral Properties Test

[0071] This test case aims to obtain UV-Vis absorption and fluorescence emission spectra of the α-cyanostyl styrene derivative prepared in Example 1 in both solution and gel states.

[0072] Sample preparation:

[0073] Solution sample: Accurately weigh the α-cyanostyl styrene derivative obtained in Example 1 and prepare it with n-hexane solvent to a concentration of 5.0 × 10⁻⁶. -6 The test solution of M.

[0074] Gel samples: The bifunctional fluorescent self-assembled gel prepared in Example 2 was used directly as the test sample.

[0075] UV-Vis absorption spectroscopy test:

[0076] Use a UV-Vis spectrophotometer. Place the solution sample in a quartz cuvette with a path length of 1 cm. Spread the gel sample evenly on the surface of the quartz plate.

[0077] Using hexane and air as blank references, the absorption spectra of the samples were scanned in the wavelength range of 200-800 nm and recorded.

[0078] Fluorescence emission spectroscopy test:

[0079] Use a fluorescence spectrometer. Place the sample as described in step 2.

[0080] The excitation wavelength was set to 417 nm, and the fluorescence emission spectrum of the sample in the range of 430-800 nm was recorded.

[0081] Test results:

[0082] Table 1. Spectral data of α-cyanostyl styrene derivatives

[0083]

[0084] Results analysis:

[0085] Depend on Figure 3 , Figure 4 As shown in Table 1, when the α-cyanostyl styrene derivative changes from a solution state to a gel state, both its maximum absorption wavelength and maximum emission wavelength undergo a red shift. Specifically, the maximum absorption wavelength shifts from 417 nm to 408 nm, and the maximum emission wavelength shifts from 474 nm to 636 nm.

[0086] This change in spectral behavior is attributed to alterations in molecular state. In dilute solutions, derivative molecules exist independently as monomers or low-aggregates. During gel formation, molecules self-assemble through intermolecular forces, forming an ordered three-dimensional network structure. This ordered aggregation leads to π-π stacking and electronic coupling between molecules, altering the ground and excited state energy levels, which macroscopically manifests as a redshift in the spectrum.

[0087] Simultaneously, the transition from the solution state to the gel state was accompanied by a significant increase in the fluorescence quantum yield, from 2.18 to 3.33. This phenomenon indicates that the vibrational and rotational degrees of freedom of molecules are effectively restricted in the three-dimensional network structure of the gel. This restriction of intramolecular motion suppresses non-radiative energy dissipation pathways, allowing more energy to be released through radiative transitions (i.e., fluorescence emission). The luminescent properties in this gel state are the basis for its ability to respond to specific changes in the external environment (such as changes in solvent polarity) and for its detection function.

[0088] in, Figure 3 The meaning is as follows:

[0089] Image a:

[0090] A comparison of the absorption of DNAE gel in hexane and DNAE solution in hexane;

[0091] The horizontal axis represents Wavelength / nm (wavelength in nanometers), and the vertical axis represents Absorbance (au) (absorbance in arbitrary units, reflecting a substance's ability to absorb light).

[0092] The solution phase exhibits an absorption peak at 417 nm, while the gel phase shows a blue shift to 408 nm.

[0093] Image b:

[0094] A comparison of the absorption of DNAE gel in DMF / H2O (v / v, 4 / 1) and DNAE solution in DMF / H2O (v / v, 4 / 1).

[0095] The solution phase exhibits an absorption peak at 415 nm, while the gel phase shows a blue shift to 396 nm.

[0096] Absorbance (au): absorbance, no actual unit (because it is related to concentration, optical path, etc.), used to compare the absorption intensity under different conditions;

[0097] Wavelength / nm: wavelength. The ultraviolet-visible spectrum typically covers 200-800nm, while this figure focuses on the visible light region of 350-600nm.

[0098] Figure 4 The meaning is as follows:

[0099] Image a:

[0100] Fluorescence comparison of gel DNAE in hexane and solution DNAE in hexane;

[0101] The horizontal axis represents Wavelength / nm (emission wavelength), and the vertical axis represents Fluorescence intensity (au) (fluorescence intensity, any unit).

[0102] The excitation wavelength was 417 nm. The maximum emission peak in the solution state was at 474 nm, while the emission peak in the gel state was red-shifted to 636 nm, a shift difference of 162 nm.

[0103] Image b:

[0104] Fluorescence comparison between gel DNAE in DMF / H2O (v / v, 4 / 1) and solution DNAE in DMF / H2O (v / v, 4 / 1);

[0105] The excitation wavelength is 417 nm. The maximum emission peak in the solution state is at 576 nm, while the emission peak in the gel state is red-shifted to 657 nm, with a shift difference of 81 nm.

[0106] Fluorescence intensity (au): Fluorescence intensity reflects the ability of a substance to emit fluorescence after being excited; the higher the value, the stronger the fluorescence.

[0107] Excitation wavelength (λ) ex): Excitation wavelength, which is fixed at 417nm in this experiment, that is, the specific wavelength at which the molecules of a substance transition to the excited state.

[0108] Test Example 2: Detection Performance Test for Short-Chain Fatty Alcohols

[0109] This test case aims to obtain fluorescence response data of the α-cyanostyl styrene derivative to different short-chain fatty alcohols in order to verify its detection capability.

[0110] Sample preparation: Accurately weigh the α-cyanostyl styrene derivative obtained in Example 1 and prepare it with n-hexane solvent to a concentration of 1.0 × 10⁻⁶. -5 M's stock solution.

[0111] Fluorescent titration test:

[0112] Take 3.0 mL of the above stock solution and place it in a quartz cuvette to measure its initial fluorescence emission spectrum.

[0113] Using a microsyringe, add different volumes of the short-chain fatty alcohol (methanol, ethanol, n-propanol, n-butanol) to the cuvette one at a time.

[0114] After each addition, the solution was mixed thoroughly and allowed to stand for 1 minute. Then, its fluorescence emission spectrum was measured under the same conditions as in Test Example 1 (excitation wavelength 417 nm). The position of the maximum emission wavelength and the relative fluorescence intensity were recorded.

[0115] Test results:

[0116] Table 2. Fluorescence response data of α-cyanostyl styrene derivatives to different fatty alcohols

[0117]

[0118] Results analysis:

[0119] Depend on Figure 5 , Figure 6 As shown in Table 2, the addition of short-chain fatty alcohols to the nonpolar n-hexane solution of the α-cyanostyl styrene derivative resulted in a red shift in the maximum emission wavelength of its fluorescence emission spectrum, along with a change in fluorescence intensity. Taking methanol as an example, with increasing amounts added, the maximum emission wavelength gradually shifted from 476 nm to above 545 nm, exhibiting a concentration-dependent effect.

[0120] The technical mechanism behind this spectral response phenomenon lies in the solvation effect. The α-cyanostylstyrene derivative molecule exhibits intramolecular charge transfer (ICT) characteristics, with its excited state exhibiting higher polarity than its ground state. In the nonpolar environment of n-hexane, the molecule exists in a certain energy state. When a highly polar short-chain fatty alcohol molecule is introduced into the system, the polarity of the solvent microenvironment increases. This polar environment can more effectively stabilize the higher-energy excited state, thereby reducing the energy level difference between the excited and ground states. This reduction in energy difference macroscopically manifests as a redshift in the fluorescence emission wavelength.

[0121] Experimental data also show that, when the same volume is added, different fatty alcohols cause different magnitudes of fluorescence spectral changes. The magnitudes of these changes follow the order: methanol > ethanol > n-propanol > n-butanol. This trend is directly related to the polarity of the alcohol molecule. As the alkyl chain length increases, the overall polarity of the alcohol molecule decreases, and its ability to stabilize the excited state of the derivative weakens accordingly, thus resulting in a smaller spectral shift. This distinguishable spectral response, related to the molecular structure and concentration of the alcohol, forms the technical basis for detecting short-chain fatty alcohols using this derivative.

[0122] in, Figure 5 The meaning is as follows:

[0123] Image a:

[0124] Methanol titration of DNAE in hexane solution (fluorescence spectrum of DNAE titration in hexane solution);

[0125] The horizontal axis represents Wavelength / nm (emission wavelength), and the vertical axis represents Fluorescence intensity (au).

[0126] As the amount of methanol added increased (labeled as 9 μL, 12 μL...20 μL), the fluorescence intensity at 474 nm gradually increased, and the emission peak red-shifted; when 20 μL of methanol was added, the fluorescence intensity increased by approximately 50.79% compared to the initial value.

[0127] Image b:

[0128] Linear relationship between fluorescence intensity and methanol concentration;

[0129] The x-axis represents methanol volume (μL), and the y-axis represents fluorescence intensity (au).

[0130] Within the methanol addition range of 9-18 μL, the fluorescence intensity showed a linear relationship with the methanol concentration, with the linear equation being y = 38324.78x + 50806.72, and the correlation coefficient R0. 2 =0.9933(R) 2 The closer to 1, the better the linearity.

[0131] Titration: Titration is an experimental method in which the analyte (methanol) is added to a system step by step and the changes in its properties (fluorescence) are observed.

[0132] Linear relationship: Used to calculate the limit of detection (LOD), the formula is LOD = 3σ / b (σ is the standard deviation of fluorescence intensity, b is the slope of the linear equation). In this experiment, the detection limit of DNAE for methanol is 0.14%.

[0133] Figure 6 The meaning is as follows:

[0134] Figure a-Figure c:

[0135] The images show fluorescence spectra for ethanol titration, n-propanol titration, and n-butanol titration, respectively.

[0136] The horizontal axis represents Wavelength / nm, and the vertical axis represents Fluorescence intensity (au).

[0137] As the amount of alcohol added increases, the fluorescence intensity first decreases and then increases (slightly different from the continuous increase of methanol, but overall it is concentration-dependent).

[0138] d-f diagram:

[0139] The fluorescence intensity-concentration linear graphs are for ethanol, n-propanol, and n-butanol, respectively.

[0140] The x-axis represents the volume of alcohol (μL), and the y-axis represents the fluorescence intensity;

[0141] The linear ranges were 12-20 μL (ethanol), 8-20 μL (n-propanol), and 12-17 μL (n-butanol). The linear equation and R0 were obtained. 2 Values ​​are labeled in the figure (e.g., ethanol R). 2 =0.9964);

[0142] The calculated detection limits were 0.33% (ethanol), 0.34% (n-propanol), and 1.08% (n-butanol).

[0143] Short-chain fatty alcohols: These are alcohols with an alkyl chain length of ≤4 (such as methanol, ethanol, n-propanol, and n-butanol).

[0144] n-Propanol / n-Butanol: n-Propanol (straight-chain structure, distinct from isopropanol) and n-Butanol (straight-chain structure), used to compare the effect of alkyl chain length on detection performance.

[0145] Test Example 3: Selectivity and Sensitivity Test for Hypochlorite Ions

[0146] This test case aims to obtain fluorescence response data of the α-cyanostylstyrene derivative to hypochlorite ions and compare it with other anions to verify its selectivity and sensitivity in detection.

[0147] Sample and reagent preparation:

[0148] Derivative stock solution: Accurately weigh the α-cyanostyl styrene derivative obtained in Example 1 and prepare it with acetonitrile solvent to a concentration of 5.0 × 10⁻⁶. -6 M's stock solution.

[0149] Anion solutions: Prepare solutions with a concentration of 5.0 × 10⁻⁶ using deionized water. -3 Stock solutions of sodium hypochlorite (NaClO) and other anionic salts (sodium chloride, sodium bromide, sodium iodide, sodium fluoride, sodium nitrate, sodium sulfate, sodium acetate) of M.

[0150] Sensitivity test (fluorescence titration):

[0151] Take 3.0 mL of the above derivative stock solution and place it in a quartz cuvette.

[0152] Using a microsyringe, different volumes of sodium hypochlorite stock solution were added to the cuvette one at a time, increasing the final concentration in the system from 0 μM to 150 μM.

[0153] After each addition, the solution was mixed thoroughly, and after reacting for 2 minutes, its fluorescence emission spectrum was measured under the same conditions as in Test Example 1 (excitation wavelength 417 nm).

[0154] Selective testing:

[0155] Prepare multiple cuvettes containing 3.0 mL of the derivative stock solution.

[0156] Add sodium hypochlorite solution or other anionic salt solution to each solution to achieve a final concentration of 150 μM for both hypochlorite ions and other anions.

[0157] After the solution was mixed thoroughly and reacted for 2 minutes, the fluorescence emission spectra of each sample were measured under the same conditions as in Test Example 1.

[0158] Analysis of reaction products:

[0159] An excess sodium hypochlorite solution was added to the derivative stock solution, and after reacting for 30 minutes, a sample was taken for high-resolution mass spectrometry (HRMS) analysis.

[0160] Test results:

[0161] Table 3. Fluorescence response data of α-cyanostyl styrene derivatives to different anions

[0162] Anions to be tested Final concentration (μM) <![CDATA[Relative fluorescence intensity (I / I0 at 583 nm)]]> <![CDATA[ClO - ]]> 150 0.43 <![CDATA[F - ]]> 150 0.81 <![CDATA[Cl - ]]> 150 0.79 <![CDATA[Br - ]]> 150 0.81 <![CDATA[I - ]]> 150 0.80 <![CDATA[AcO - ]]> 150 0.79 <![CDATA[NO3 - ]]> 150 0.79 <![CDATA[SO4 2- ]]> 150 0.80

[0163] Results analysis:

[0164] Depend on Figure 7 As shown in Table 3, the addition of hypochlorite ions to the solution of the α-cyanostylstyrene derivative resulted in a regular decrease in fluorescence intensity at 583 nm with increasing hypochlorite ion concentration. In contrast, the addition of equal concentrations of other anions (such as F-, Cl-, Br-) resulted in a significant decrease in fluorescence intensity. - The fluorescence intensity of the solution did not change significantly. This experimental result indicates that the derivative has a recognizable fluorescence response to hypochlorite ions.

[0165] The decrease in fluorescence intensity is technically caused by an irreversible chemical reaction initiated by hypochlorite ions. The molecular structure of the α-cyanostylstyrene derivative contains a carbon-carbon double bond that is sensitive to oxidants. Hypochlorite ions, acting as an oxidant, react with this carbon-carbon double bond, causing it to break. This double bond is crucial for maintaining the entire π-conjugated molecular system and the intramolecular charge transfer (ICT) effect. The breaking of the double bond disrupts the effective pathway of the ICT process, thereby terminating the molecule's luminescence ability, macroscopically manifested as fluorescence quenching.

[0166] The selectivity of this detection function stems from the high specificity of the aforementioned reaction. Among the tested anions, only the hypochlorite ion possesses the chemical property to effectively oxidize and cleave the carbon-carbon double bond under the current experimental conditions. Other anions do not possess this reactivity and therefore cannot disrupt the conjugated structure of the molecule, thus not causing a significant decrease in fluorescence intensity. High-resolution mass spectra ( Figure 8 A signal peak matching the molecular weight of the aldehyde fragment generated after the double bond breakage was detected, providing direct structural evidence for the reaction mechanism. Therefore, this fluorescence signal change based on a specific chemical reaction forms the basis for the selective detection of hypochlorite ions using this derivative.

[0167] in, Figure 7The meaning is as follows:

[0168] Image a:

[0169] ClO-titration of DNAE (5×10) -3 M)inacetonitrile (DNAE acetonitrile solution (concentration 5×10) - 6 (fluorescence spectrum of ClO- titration at mol / L);

[0170] The horizontal axis represents Wavelength / nm, and the vertical axis represents Fluorescence intensity (au).

[0171] As the amount of ClO- added increases (labeled as 2eq.5eq.30eq., where eq. is equivalent, referring to the molar ratio of ClO- to DNAE), the fluorescence intensity at 583nm gradually quenches.

[0172] When 30 eq.ClO- was added, the fluorescence intensity decreased by 57.9%, and the fluorescence disappeared visibly (under 365 nm UV excitation).

[0173] Image b:

[0174] Fluorescence emission of DNAE in acetonitrile with different anions (30.0 eq.) (Fluorescence spectrum of DNAE in acetonitrile solution with different anions (30 equivalents) added);

[0175] The horizontal axis represents Wavelength / nm, and the vertical axis represents Fluorescence intensity (au).

[0176] Anions include Br - Cl - F - I - NO3 - SO4 2- Of the 13 anions, only ClO- significantly quenched fluorescence, while other anions only caused a slight decrease in intensity, demonstrating the high selectivity of DNAE for ClO-.

[0177] Figure c:

[0178] Linear relationship between fluorescence intensity and ClO- concentration;

[0179] The horizontal axis represents ClO-equivalents (eq.).

[0180] The vertical axis represents Fluorescence intensity (au);

[0181] The equation is linear in the range of 2-30 eq, and the equation is y = -634.17x + 157767.92, R. 2 =0.9982; the calculated detection limit is 4.58 μM (micromoles / liter), which is far below the physiological critical concentration (0.01-10 mM).

[0182] d diagram:

[0183] Time-dependent fluorescence response of DNAE to ClO-;

[0184] The horizontal axis represents Time (s), and the vertical axis represents Fluorescence intensity (au). After adding ClO-, the fluorescence intensity rapidly decreased to a stable value within 1 second, demonstrating a fast response speed (1 second).

[0185] Anions: These are negatively charged ions (such as ClO-, Br-). - SO4 2 -), used to verify the selectivity of DNAE for ClO- (excluding interference from other anions);

[0186] Time-dependent response: This reflects the sensor's response speed; a fast response of 1 second meets the requirements for real-time detection.

[0187] Detection limit (LOD): The low detection limit of 4.58 μM indicates that DNAE has high sensitivity to ClO- and can be used for trace ClO- detection (such as residues in drinking water).

[0188] Figure 8 The meaning is as follows:

[0189] The horizontal axis (X-axis) is m / z, which is the mass-to-charge ratio, reflecting the ratio of the ion's mass to its charge (in this figure, the charge is +1, so m / z ≈ ion mass).

[0190] The vertical axis (Y-axis) represents the relative abundance (%), which reflects the proportion of ions with that mass-to-charge ratio (the higher the abundance, the more ions there are).

[0191] Key Peak:

[0192] m / z = 199.1800, labeled as [6-(Dimethylamino)-2-naphthaldehyde+H] + It is the protonated ion of 6-(dimethylamino)-2-naphthaldehyde (one of the starting materials of DNAE), with the highest abundance (about 100%), proving that after DNAE reacts with ClO-, the carbon-carbon double bond in the molecule is oxidized and broken to generate 6-(dimethylamino)-2-naphthaldehyde.

[0193] HRMS (High-Resolution Mass Spectrometry): High-resolution mass spectrometry can accurately determine the mass of ions (error typically <10). -6 ), used to confirm the structure of the reaction products;

[0194] Relative abundance (%): The relative abundance is defined as 100% for the ion with the highest abundance, and the abundance of other ions is compared with it to determine the main components of the product.

[0195] [M+H] + Protonated molecular ion: refers to a molecule (M) that has a proton (H) bonded to it in a mass spectrum. + The ions formed are an important basis for confirming molecular mass.

Claims

1. A method for preparing a bifunctional fluorescent self-assembled gel, characterized in that, Includes the following steps: S1. 6-(dimethylamino)-2-naphthaldehyde and N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide were subjected to a reflux reaction in the presence of anhydrous ethanol solvent and piperidine catalyst. After the reaction was completed, the α-cyanostyrene derivative was obtained by purification. S2. Dissolve the α-cyanostyrene derivative obtained in step S1 in an organic solvent, heat until the α-cyanostyrene derivative is completely dissolved, and then cool to room temperature to obtain the bifunctional fluorescent self-assembled gel.

2. The method for preparing the bifunctional fluorescent self-assembled gel according to claim 1, characterized in that, In step S1, the molar ratio of 6-(dimethylamino)-2-naphthaldehyde to N-(2-(2-cyanopropamido)ethyl)-3,4,5-tris(dodecyl)benzamide is 1:(0.9-1.2).

3. The method for preparing the bifunctional fluorescent self-assembled gel according to claim 1, characterized in that, In step S1, the duration of the heating reflux reaction is 10-14 hours.

4. The method for preparing the bifunctional fluorescent self-assembled gel according to claim 1, characterized in that, In step S1, the purification process includes: First, the anhydrous ethanol solvent is removed by vacuum distillation, and then the remaining product is purified by column chromatography.

5. The method for preparing the bifunctional fluorescent self-assembled gel according to claim 1, characterized in that, In step S2, the organic solvent is selected from at least one of n-hexane, acetone, methanol, tetrahydrofuran, ethyl acetate, ethanol, acetonitrile, toluene, N,N-dimethylformamide / water, dimethyl sulfoxide, 1,4-dioxane, 1,2-dichlorobenzene, or 1,3,5-trimethylbenzene.

6. The method for preparing the bifunctional fluorescent self-assembled gel according to claim 5, characterized in that, The organic solvent is n-hexane, and the concentration of the α-cyanostyrene derivative in the n-hexane is 2.0-2.5 mg / mL.

7. The method for preparing the bifunctional fluorescent self-assembled gel according to claim 5, characterized in that, The organic solvent is a mixed solvent of N,N-dimethylformamide and water in a volume ratio of 4:1, and the concentration of the α-cyanostyrene derivative in the mixed solvent is 19.0-21.0 mg / mL.

8. Application of bifunctional fluorescent self-assembly gel, characterized in that, The bifunctional fluorescent self-assembled gel obtained by the preparation method according to any one of claims 1-8 is used to detect methanol, short-chain fatty alcohols of ethanol, and hypochlorite ions with high selectivity and high sensitivity.

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