A bis-cyano stilbene fluorescent probe and a synthesis method and application thereof

Abstract

The application discloses a kind of double cyano stilbene fluorescent probes and synthesis method and application, belong to organic synthesis and analytical chemistry technical field, the fluorescent probe chemical name is 1,4- (4-dodecanoyl amino phenyl-1-cyanovinyl) benzene, molecular formula is C 48 H 62 N4O2, with the aggregation-induced emission characteristics of double cyano stilbene as base element, prepared by appropriate chemical modification;This fluorescent probe is light yellow in pure tetrahydrofuran solution, there is weak light yellow fluorescence at 450nm, but when in tetrahydrofuran-water mixed solution, the probe emits bright yellow fluorescence at 540nm, and the fluorescent probe in tetrahydrofuran-water mixed solution can be with Pd 2+ Strong supramolecular interaction occurs, so that its fluorescence intensity is significantly weakened, and in a certain range, fluorescence drop degree is proportional to the concentration of Pd 2+ Therefore, the fluorescent probe can be used as a kind of relatively ideal Pd 2+ Quick detection fluorescent probe, for selective sensitive detection of Pd 2+ In environment.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis and analytical chemistry technology, specifically relating to a dicyandiamide fluorescent probe, its synthesis method, and its application. Background Technology

[0002] Palladium is a rare heavy metal widely used in automotive manufacturing, aerospace, dental materials, and other fields. In chemistry, it is frequently used as a reaction catalyst. With the widespread use of palladium, an increasing number of palladium compounds are entering the environment through industrial wastewater discharge, causing pollution. Related studies have shown that Pd... 2+ It can form complexes with thiol-containing proteins, DNA, and RNA, thereby affecting normal human physiological processes. It also affects metabolism, acid-base balance, and electrolyte balance. Therefore, it is necessary to develop a rapid detection method for Pd that is efficient, selective, and sensitive. 2+ The method. Previously, Pd 2+ The main detection methods include spectrophotometry, ICP-MS, radioisotope dilution, X-ray fluorescence spectroscopy, and voltammetry. These methods are relatively complex to operate, take a long time to detect, and cannot be used for in-situ detection.

[0003] Fluorescent probe molecular detection boasts advantages such as high sensitivity, good selectivity, convenience, speed, low cost, and on-site detection. Among these, organic fluorescent molecules show the broadest application prospects. However, traditional organic fluorescent probes are prone to aggregation-induced quenching in aqueous solutions, limiting their practical applications. In recent years, aggregation-induced emission (AIE) fluorescent probes have attracted considerable attention as a novel type of probe capable of effective emission in aqueous solutions. AIE fluorescent probes not only inherit the advantages of traditional organic fluorescent probes while overcoming their biggest drawback (aggregation-induced quenching, ACQ), but also provide good fluorescence even at high concentrations or during aggregation. Furthermore, through appropriate 950 functional group modification, novel fluorescent probes with selective recognition capabilities for various ions or organic molecules can be obtained. Therefore, utilizing the characteristics of aggregation-induced emission, and through appropriate chemical modification, a highly selective, simple, rapid, and sensitive detection method for Pd can be prepared. 2+ The novel fluorescent probe has broad application prospects and practical value.

[0004] The article "A water-soluble ESIPT fluorescent probe with high quantum yield and red emission for ratiometric detection of organic and organic palladium" by T. Gao et al. (An Asian journal, Chemistry, 2015, 10: 1142-1145) discloses a detection probe. However, this probe is easily interfered with by palladium substances of other valence states and cannot distinguish divalent palladium substances from other palladium substances. Patent CN109912533A provides a palladium-responsive fluorescent probe and its preparation method. The fluorescent probe itself exhibits blue fluorescence in a buffer solution and can specifically react with tetrakis(triphenylphosphine)palladium to generate a product with yellow fluorescence, thus achieving a specific response to palladium. However, this fluorescent probe is only suitable for the detection of zero-valent palladium and cannot be applied to Pd. 2+ The field of testing. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a dicyandiamide fluorescent probe, its synthesis method, and its application, wherein the fluorescence intensity is within the range of metal ions Pd. 2+ The quenching effect is significant in the presence of [specific ion name], and the presence of other ions has minimal interference with the detection results of this fluorescent probe. Utilizing the rapid decrease in fluorescence intensity of the fluorescent probe, the detection of Pd in ​​solution can be achieved. 2+ Highly efficient selective detection.

[0006] The technical solution of the present invention is as follows:

[0007] One objective of this invention is to provide a dicyandiamide fluorescent probe, named 1,4-bis-(4-dodecanoylaminophenyl-1-cyanovinyl)benzene, with the molecular formula C1 48 H 62 N4O2 is a dicyanostilbene compound modified with dodecylamine, and its chemical structural formula is as follows:

[0008]

[0009] Furthermore, the infrared spectral characterization of the fluorescent probe is as follows: (KBr), v / cm -1 :3302(NH),1661(C=O);

[0010] The hydrogen NMR spectrum characterization is as follows: (400 Hz, DMSO) 1H NMR (400MHz, DMSO) δ10.21(s,2H,NH),8.04(s,2H,CH=CCN),7.94(d,J=8.0Hz,4H,ArH),7.86(s,4H,ArH),7.76 (d,J=8.0Hz,4H,ArH),2.33(t,J=6.0Hz,4H,CH2CO),1.59(bs,4H,CH2),1.23(bs,32H,CH2),0.85(s,6H,CH3);

[0011] The carbon NMR spectrum is as follows: (101 MHz, DMSO) δ 185.44, 149.61, 131.32, 130.90, 129.92, 128.19, 126.90, 126.68, 119.39, 97.01, 31.76, 31.38, 29.45, 29.37, 29.18, 29.09, 25.44, 22.56, 14.43;

[0012] MALDI-TOF mass spectrometry (m / s): Calculated value C 48 H 62 N4O2 726.49 (M) + The measured value was 727.845 [MH]. + .

[0013] The second objective of this invention is to provide a method for preparing a dicyandiamide fluorescent probe, comprising the following steps:

[0014] (1) Add terephthalonitrile, 4-acetaminobenzaldehyde and sodium hydroxide to anhydrous ethanol and stir under reflux. Use thin layer chromatography to detect the reaction progress. After the reaction is complete, cool and filter. Wash the filter cake with water and ethanol in turn. Then dry the filter cake under vacuum to obtain a yellow solid, namely 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene.

[0015] (2) Dissolve 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene in a 1,4-dioxane solution, add concentrated hydrochloric acid and raise the temperature to carry out the reaction. After the reaction, cool and add sodium hydroxide aqueous solution until the solution is neutral. Stir and filter to obtain an orange-yellow solid, namely 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene.

[0016] (3) Under nitrogen protection, 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, dodecyl chloride and pyridine were stirred in dry tetrahydrofuran at room temperature. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was recrystallized with methanol and water. Then, it was recrystallized a second time with ethyl acetate and petroleum ether to obtain a pale yellow solid, which is the dicyandiamide fluorescent probe.

[0017] Furthermore, in step (1), the ratio of the amounts of terephthalonitrile, 4-acetaminobenzaldehyde and sodium hydroxide is 1 equivalent: 2-3 equivalents: 1.5-2 equivalents.

[0018] Furthermore, in step (2), the amount of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene used is 1 equivalent, and the ratio of the amount of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene to 1,4-dioxane is 1:20 equivalent.

[0019] Furthermore, in step (2), the amount of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene used is 1 equivalent, the reaction time is 6-7 h, and the stirring time is 1-2 h.

[0020] Furthermore, in step (3), the ratio of the amounts of 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, dodecyl chloride and pyridine is 1 equivalent: 2 to 5 equivalents: 2 to 5 equivalents.

[0021] Furthermore, in step (3), the volume ratio of methanol to water is 1:5.

[0022] Furthermore, in step (3), the volume ratio of ethyl acetate to petroleum ether is 1:50.

[0023] The third objective of this invention is to provide an application of a dicyandiphenyl styrene fluorescent probe, which involves adding a tetrahydrofuran-water mixture containing the dicyandiphenyl styrene fluorescent probe to the sample solution to react with Pd in ​​the sample solution. 2+ Strong supramolecular interactions occur, based on the decreased fluorescence intensity after the reaction and Pd 2+ By comparing the standard working curves of concentration change, the concentration of Pd in ​​the sample solution can be determined. 2+ Content determination.

[0024] Furthermore, the fluorescent probe described in this invention is prepared into a tetrahydrofuran-water solution of a certain concentration, and Pd solutions with concentration gradients are prepared according to molar multiples of the fluorescent probe concentration of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, and 5.0. 2+ A series of solutions, wherein the fluorescent probe is reacted with Pd 2+ The series of solutions were thoroughly shaken and mixed, and the fluorescence intensity of the mixed solution was measured. A graph was established with fluorescence intensity as the ordinate and Pd as the modulus. 2+ Fluorescence intensity with concentration as the x-axis varies with Pd 2+ Standard working curve for concentration gradient change.

[0025] Furthermore, the fluorescent probe is combined with the target Pd2+ The solutions were mixed, and the fluorescence intensity of the mixture was measured. The obtained fluorescence intensity value was compared with the Pd value established above. 2+ Compare the concentration gradient changes with the standard working curves, and read the Pd concentration in the test solution from the curves. 2+ content.

[0026] Furthermore, the volume ratio of tetrahydrofuran to water in the mixed solution is 5:95.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1. This invention utilizes the unique aggregation-induced emission (AIE) behavior of aggregation-induced emission materials. Using dicyandiphenyl styrene (DIS), which possesses AIE properties, as a building block, a DISFIR fluorescent probe was constructed through appropriate chemical modification, solving the problem of fluorescent molecule aggregation quenching. Furthermore, this fluorescent probe is pale yellow in pure tetrahydrofuran solution, exhibiting only weak pale yellow fluorescence at 450 nm. However, when placed in a tetrahydrofuran-water mixed solution, the probe emits bright yellow fluorescence at 540 nm. The tetrahydrofuran-water mixed solution containing this fluorescent probe is then mixed with Pd... 2+ Mixing can generate strong supramolecular interactions, which significantly weakens its fluorescence intensity, and within a certain range, the degree of fluorescence decrease is similar to that of Pd. 2+ The concentration of Pd is directly proportional to its concentration. Based on this characteristic, the fluorescent probe can also serve as an ideal sensor for detecting Pd. 2+ Selective and sensitive detection.

[0029] 2. The dicyandiphenyl styrene fluorescent probe disclosed in this invention has excellent anti-interference ability and can selectively detect Pd. 2+ In Pd 2+ Its fluorescence intensity changes significantly in the presence of [specific ion], and the presence of other ions has virtually no interference with the fluorescence probe's response to Pd. 2+ The detection of Pd is performed using this fluorescent probe. Furthermore, this probe is applicable to a wide pH range, and the detection method is simple, rapid, accurate, and sensitive, making it suitable for various complex environments and real-world samples. 2+ Sensitive detection.

[0030] 3. Compared with existing fluorescent probe technologies, the dicyandiphenyl styrene fluorescent probe synthesis method provided by this invention is simple, the operation steps are easy, it does not require high-energy excitation, and it does not damage biological samples. It is environmentally friendly and can be widely used in life sciences, environmental sciences, medical materials and other fields. It is one of the important development directions in the field of palladium ion detection research.

[0031] Figure Labels

[0032] Figure 1This is a flowchart illustrating the synthesis process of the dicyandiphenyl styrene fluorescent probe described in this invention.

[0033] Figure 2 The infrared spectra of the functional groups of the dicyandiphenyl styrene fluorescent probe described in Example 3 of this invention are shown below.

[0034] Figure 3 The 1H NMR spectrum of the dicyandiphenyl styrene fluorescent probe described in Example 3 of this invention;

[0035] Figure 4 The image shows the carbon NMR spectrum of the dicyandiphenyl styrene fluorescent probe described in Example 3 of this invention.

[0036] Figure 5 This is the mass spectrum of the dicyandiphenyl styrene fluorescent probe described in Example 3 of the present invention;

[0037] Figure 6 The image shows the fluorescence emission spectra of a tetrahydrofuran-water mixed solution containing the dicyandiphenyl styrene fluorescent probe described in the performance test of this invention, mixed with different ions. The inset shows the dicyandiphenyl styrene fluorescent probe and Pd. 2+ Fluorescence image under 365nm ultraviolet light illumination;

[0038] Figure 7 The solution contained a tetrahydrofuran-water mixture of the dicyandiphenyl styrene fluorescent probe described in the performance test of this invention and different concentrations of Pd. 2+ Fluorescence spectrum;

[0039] Figure 8 The solution contains a tetrahydrofuran-water mixture of the dicyandiphenyl styrene fluorescent probe described in Example 4 of this invention and different equivalent concentrations of Pd. 2+ Standard working curve of fluorescence intensity change after mixing;

[0040] Figure 9 A tetrahydrofuran-water mixed solution containing the dicyandiphenyl styrene fluorescent probe described in the performance test of this invention and other ions (or containing Pd). 2+ A comparison of the ratio of fluorescence intensity of the mixture (with other ions) to its own fluorescence intensity. The other ions are in the following order: 1 = Li + 2 = Na + ,3=K + ,4=Cs + ,5=Mg 2+ ,6=Ca 2+ ,7=Pd 2+ ,8=Zn 2+ ,9=Cd 2+ ,10=Fe 3+ ,11=Co 2+ ,12=Ni2+ ,13=Ba 2+ ,14=Pb 2+ ,15=Ag + ,16=Cu 2+ ,17=Mn 2 + ,18=Cr 3+ ,19=Cl - ,20=Br - ,21=NO3 - ,22=SO4 2- ,23=PO4 3- ,24=HPO4 2 -,25=CO3 2- . Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0042] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0043] In the quantitative experiments in the following examples, three replicate experiments were set up, and the average value of the results was taken.

[0044] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0045] Example 1

[0046] This embodiment provides a dicyandiphenyl styrene fluorescent probe, the synthesis method of which is as follows: Figure 1 As shown, it includes the following steps:

[0047] (1) 1 mmol of phenylacetonitrile, 2 mmol of 4-acetaminobenzaldehyde and 1.5 mmol of sodium hydroxide were added to 30 mL of anhydrous ethanol and stirred and refluxed for 12 h. The reaction progress was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled and filtered. The filter cake was washed with water and ethanol in turn, and then the filter cake was dried under vacuum to obtain a yellow solid, namely 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene.

[0048] (2) Dissolve 1 mmol of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene in 30 mL of 1,4-dioxane solution, add 12 M concentrated hydrochloric acid, raise the temperature to 100 °C to react, react for 7 h, cool and add 1 M sodium hydroxide aqueous solution until the solution is neutral, stir for 1 h and filter to obtain an orange-yellow solid, namely 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene;

[0049] (3) Under nitrogen protection, 1 mmol of 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, 2 mmol of dodecyl chloride, and 2 mmol of pyridine were stirred in 25 mL of dry tetrahydrofuran at room temperature for 12 h. After the reaction was complete, the solvent was removed by vacuum distillation. The solution was recrystallized from the solution using 50 mL of a 1:5 mixture of methanol and water, and then recrystallized again using 35 mL of a 1:50 mixture of ethyl acetate and petroleum ether to obtain a pale yellow solid, which is the dicyandiamide fluorescent probe with the molecular formula C. 48 H 62 N4O2, yield 83%.

[0050] Example 2

[0051] This embodiment provides a method for synthesizing a dicyandiamide fluorescent probe, such as... Figure 1 As shown, it includes the following steps:

[0052] (1) 1 mmol of phenylacetonitrile, 2.5 mmol of 4-acetaminobenzaldehyde and 1.7 mmol of sodium hydroxide were added to 35 mL of anhydrous ethanol and stirred under reflux for 12 h. The reaction progress was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled and filtered. The filter cake was washed with water and ethanol in sequence, and then the filter cake was dried under vacuum to obtain a yellow solid, namely 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene.

[0053] (2) Dissolve 1 mmol of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene in 35 mL of 1,4-dioxane solution, add 12 M concentrated hydrochloric acid, raise the temperature to 100 °C to react, react for 6.5 h, cool and add 1 M sodium hydroxide aqueous solution until the solution is neutral, stir for 1.5 h and filter to obtain an orange-yellow solid, namely 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene;

[0054] (3) Under nitrogen protection, 1 mmol of 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, 3 mmol of dodecyl chloride, and 3 mmol of pyridine were stirred in 30 mL of dry tetrahydrofuran at room temperature for 12 h. After the reaction was complete, the solvent was evaporated under reduced pressure. The solution was recrystallized from the solution using 40 mL of a 1:5 mixture of methanol and water, and then recrystallized again using 30 mL of a 1:50 mixture of ethyl acetate and petroleum ether to obtain a pale yellow solid, which is the dicyandiamide fluorescent probe with the molecular formula C. 48 H 62 N4O2, yield 85%.

[0055] Example 3

[0056] This embodiment provides a method for synthesizing a dicyandiamide fluorescent probe, such as... Figure 1 As shown, it includes the following steps:

[0057] (1) 1 mmol of phenylacetonitrile, 3 mmol of 4-acetaminobenzaldehyde and 2 mmol of sodium hydroxide were added to 40 mL of anhydrous ethanol and stirred and refluxed for 12 h. The reaction progress was detected by thin-layer chromatography. After the reaction was completed, the mixture was cooled and filtered. The filter cake was washed with water and ethanol in turn, and then the filter cake was dried under vacuum to obtain a yellow solid, namely 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene.

[0058] (2) Dissolve 1 mmol of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene in 30 mL of 1,4-dioxane solution, add 12 M concentrated hydrochloric acid, raise the temperature to 100 °C to react, react for 6 h, cool and add 1 M sodium hydroxide aqueous solution until the solution is neutral, stir for 2 h and filter to obtain an orange-yellow solid, namely 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene;

[0059] (3) Under nitrogen protection, 1 mmol of 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, 5 mmol of dodecyl chloride, and 5 mmol of pyridine were stirred in 35 mL of dry tetrahydrofuran at room temperature for 12 h. After the reaction was complete, the solvent was evaporated under reduced pressure. The solution was recrystallized from the solution using 45 mL of a 1:5 mixture of methanol and water, and then recrystallized again using 35 mL of a 1:50 mixture of ethyl acetate and petroleum ether to obtain a pale yellow solid, which is the dicyandiamide fluorescent probe with the molecular formula C. 48 H 62 N4O2, yield 86%.

[0060] Example 4

[0061] This embodiment provides an application of a dicyandiamide fluorescent probe, including the following steps:

[0062] (1) Prepare a tetrahydrofuran-water mixed solution containing the dicyandiamide fluorescent probe described in Example 3 above, wherein the volume ratio of tetrahydrofuran to water is 5:95. Prepare Pd solutions with gradient concentrations according to molar multiples of 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, and 5.0 of the fluorescent probe concentration. 2+ A series of solutions were prepared by reacting the mixed solution with Pd. 2+ The series of solutions were thoroughly shaken and mixed, and the fluorescence intensity of the mixed solution was measured. A graph was established with fluorescence intensity and Pd as the ordinate. 2+ A standard working curve with concentration on the x-axis, such as... Figure 8 As shown;

[0063] (2) The tetrahydrofuran-water mixture containing the dicyandiphenyl styrene fluorescent probe was reacted with the Pd to be tested. 2+ After mixing the solutions, compare the measured fluorescence intensity values ​​with the standard working curve obtained in step (1), and read the Pd concentration in the test solution from the curve. 2+ content.

[0064] Performance testing:

[0065] 1. Selective testing

[0066] To 1×10 -5 Add 1×10 mol / L of tetrahydrofuran-water mixed solution containing the dicyandiphenyl styrene fluorescent probe described in Example 3. -5 The fluorescence emission spectra of the solutions after the reaction were measured for various ions at mol / L, and the results are as follows: Figure 6 As shown.

[0067] like Figure 6 As shown, when performing different ion tests, the tetrahydrofuran-water mixed solution containing the dicyandiamide fluorescent probe only showed up for Pd. 2+ The fluorescence exhibits a clear response and significant quenching, which can also be directly observed in the inset, indicating that this fluorescent probe is effective against Pd. 2+ It has good selective recognition capabilities.

[0068] 2. Correlation test

[0069] To 1×10 -5 Different concentrations of Pd were added to a tetrahydrofuran-water mixed solution containing the dicyandiamide fluorescent probe described in Example 3 at a concentration of mol / L. 2+ The fluorescence emission spectra of the solutions after the reaction were measured, and the results are as follows: Figure 7 As shown.

[0070] exist Figure 7 Among them, with Pd 2+ As the solution concentration continued to increase, the fluorescence intensity of the tetrahydrofuran-water mixed solution containing the dicyandiamide fluorescent probe showed a significant decreasing trend. Therefore, it can be inferred that the fluorescence intensity of this fluorescent probe mixed solution is related to the fluorescence intensity of Pd. 2+ There is a good linear relationship between concentrations, which can be applied to Pd. 2+ Related quantitative analysis activities.

[0071] 3. Anti-interference test

[0072] To 1×10 -5 Add 1×10 mol / L of tetrahydrofuran-water mixed solution containing the dicyandiphenyl styrene fluorescent probe described in Example 3. -5 mol / L other ions (or other ions + Pd)2+ The fluorescence emission spectra of the solutions after the reaction were measured respectively, and the results are as follows: Figure 9 As shown.

[0073] Figure 9 In the middle, I is 1×10 -5 A tetrahydrofuran-water mixed solution containing a dicyandiamide fluorescent probe at a concentration of mol / L and 1×10 -5 Other ions (or other ions + Pd) at mol / L 2+ The fluorescence intensity after the reaction, I o 1×10 -5 The fluorescence intensity of the mol / L fluorescent probe mixed solution. Figure 9 It can be seen that the fluorescence ratios of the fluorescent probes are all close to 1 after the addition of other ions, indicating that the other ions have little effect on the fluorescence of this fluorescent probe. However, the addition of Pd to other ions... 2+ Subsequently, the fluorescence intensity of this fluorescent probe significantly decreased, indicating that other ions affected the Pd of this fluorescent probe. 2+ The impact of interference on sensitive detection is minimal.

[0074] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A dicyandiphenyl styrene fluorescent probe, characterized in that, The fluorescent probe was named 1,4-bis-(4-dodecanoylaminophenyl-1-cyanovinyl)benzene, with the molecular formula C1. 48 H 62 N4O2 is a dicyanostilbene compound modified with dodecylamine, and its chemical structural formula is as follows: 。 2. A method for synthesizing the dicyandiphenyl styrene fluorescent probe as described in claim 1, characterized in that, Includes the following steps: (1) Add terephthalonitrile, 4-acetaminobenzaldehyde and sodium hydroxide to anhydrous ethanol and stir under reflux. Use thin-layer chromatography to detect the reaction progress. After the reaction is complete, cool and filter. Wash the filter cake with water and ethanol in turn. Then dry the filter cake under vacuum to obtain a yellow solid, namely 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene. (2) Dissolve 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene in 1,4-dioxane solution, add concentrated hydrochloric acid and raise the temperature to react. After the reaction, cool and add sodium hydroxide aqueous solution until the solution is neutral. Stir and filter to obtain an orange-yellow solid, namely 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene. (3) Under nitrogen protection, 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, dodecyl chloride and pyridine were stirred in dry tetrahydrofuran at room temperature. After the reaction was completed, the solvent was removed by vacuum distillation, and the mixture was recrystallized with methanol and water. Then, it was recrystallized a second time with ethyl acetate and petroleum ether to obtain a pale yellow solid, which is the dicyandiamide fluorescent probe.

3. The method for synthesizing a dicyandiamide fluorescent probe as described in claim 2, characterized in that, In step (1), the ratio of the amounts of terephthalonitrile, 4-acetaminobenzaldehyde and sodium hydroxide is 1 equivalent: 2-3 equivalents: 1.5-2 equivalents.

4. The method for synthesizing a dicyandiamide fluorescent probe as described in claim 2, characterized in that, In step (2), the amount of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene used is 1 equivalent, and the ratio of the amount of 1,4-bis-(4-acetaminophenyl-1-cyanovinyl)benzene to 1,4-dioxane is 1:20 equivalent.

5. The method for synthesizing a dicyandiphenyl styrene fluorescent probe as described in claim 2, characterized in that, The reaction time in step (2) is 6-7 h.

6. The method for synthesizing a dicyandiamide fluorescent probe as described in claim 2, characterized in that, The stirring time in step (2) is 1-2 h.

7. The method for synthesizing a dicyandiphenyl styrene fluorescent probe as described in claim 2, characterized in that, In step (3), the ratio of the amounts of 1,4-bis-(4-aminophenyl-1-cyanovinyl)benzene, dodecyl chloride and pyridine is 1 equivalent: 2-5 equivalents: 2-5 equivalents.

8. The method for synthesizing a dicyandiphenyl styrene fluorescent probe as described in claim 2, characterized in that, In step (3), the volume ratio of methanol to water used for recrystallization is 1:

5.

9. The method for synthesizing a dicyandiamide fluorescent probe as described in claim 2, characterized in that, In step (3), the volume ratio of ethyl acetate to petroleum ether used for secondary recrystallization is 1:

50.

10. A dicyandiphenyl styrene fluorescent probe as described in claim 1 in detecting Pd in ​​solution. 2+ The application of [the technology] is characterized by, The fluorescent probe was dissolved in a tetrahydrofuran-water mixture to form a probe solution, which was then mixed with the test solution. Pd was detected by changes in fluorescence intensity. 2+ In the tetrahydrofuran-water mixed solution, the volume ratio of tetrahydrofuran to water is 5:95.

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