Salicylic hydrazide derivatives containing pyrazole groups having optical switching properties, methods of preparation and use

Abstract

The application discloses a salicylic hydrazide derivative containing a pyrazole group with light switch performance, a preparation method and application. The derivative can recognize copper ions, sulfur ions, trifluoroacetic acid and triethylamine as a fluorescent probe. Meanwhile, the partial configuration of the derivative can be changed by irradiation of 302 wavelength light, the fluorescent emission intensity of the derivative is enhanced, and the detection sensitivity of the above-mentioned substances is enhanced. The series of fluorescent probes have the advantages of simple synthesis route, high yield, wide detection surface, high sensitivity and light control.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of fluorescent probes, and particularly relates to a salicylic hydrazide derivative containing a pyrazole group with light switch performance and use thereof as a fluorescent probe. BACKGROUND

[0002] Fluorescent molecules, as a classic smart material, have a wide range of applications, such as anti-counterfeiting, biological imaging, storage devices and security inks. In addition, the emission wavelength range and intensity of some fluorescent materials can be easily affected by different ions, acid-base, heat, light, electricity, mechanics and magnetism. These special characteristics make smart fluorescent molecules attract the attention of researchers and are widely used in fluorescent probes and information encryption.

[0003] Guo et al. (Journal of Materials Chemistry C, 2022, 10, 11016) reported a class of copper ion quenching type probes containing Schiff base structure, although the compound has high sensitivity, but the detection target is single, which limits its application value. Although these fluorescent materials have outstanding advantages in identifying special substances, how to effectively organize smart fluorescent molecules to respond to multiple stimuli is a great challenge, and ensure the mutual independence between different stimuli, which hinders the further application and progress of fluorescent molecules. Therefore, it is of great significance to develop new smart fluorescent molecules with multiple stimuli and to preliminarily explain their action mechanism. SUMMARY

[0004] In order to solve the problem that the current fluorescent probe has single action and narrow application, the present application aims to provide a salicylic hydrazide derivative containing a pyrazole group, and the compound is used as a fluorescent probe to recognize copper ions, sulfur ions, trifluoroacetic acid and triethylamine. At the same time, irradiation with 302 nanometer wavelength light can realize the partial configuration transformation (E formula→Z formula) of the compound, enhance its fluorescence emission intensity and further enhance the detection sensitivity of the above-mentioned substances.

[0005] The technical solution to achieve the purpose of the present application is: a salicylic hydrazide derivative containing a pyrazole group with light switch performance, which has the following structure:

[0006]

[0007] Among them,

[0008] R 1 -R 4 independently any of hydrogen atom, fluorine atom, chlorine atom, iodine atom and methyl group.

[0009] Preferably, R 1 -R 4is a hydrogen atom.

[0010] The preparation method of the salicylic hydrazide derivative containing a pyrazole group with the optical switching performance comprises the following steps:

[0011]

[0012] The preparation method of the salicylic hydrazide derivative containing a pyrazole group with the optical switching performance comprises the following steps:

[0013]

[0014] Preferably, in step (1), the substitution reaction is carried out in the presence of an organic solvent ethanol.

[0015] Preferably, in step (1), the substitution reaction is carried out at a temperature of 60±5℃ for 4 hours.

[0016] Preferably, in step (1), the molar ratio of the compound I to the hydrazine hydrate is 1:5.

[0017] Preferably, in step (2), the reaction is carried out in the presence of an organic solvent ethanol.

[0018] Preferably, in step (2), the reaction is carried out at a temperature of 60-75℃ for 6 hours.

[0019] Preferably, in step (2), the molar ratio of the reactant 2 to the 1-methyl-1H-pyrazole-3-carboxaldehyde is 1:1.5.

[0020] The application also provides the use of the target compound as a fluorescent probe, which can identify copper ions, sulfur ions, trifluoroacetic acid or triethylamine.

[0021] Compared with the prior art, the application has the following advantages:

[0022] (1) The target compound involved in the application can be used as a fluorescent probe to identify Cu 2+ , S 2- , trifluoroacetic acid, triethylamine and other substances.

[0023] (2) The series of fluorescent probes have the advantages of simple synthesis route, high yield, wide detection surface and light control.

[0024] (3) The irradiation of 302 nanometer wavelength light can realize the configuration conversion (E formula→Z formula) of some compounds, enhance the fluorescence emission intensity and further enhance the detection sensitivity of the above-mentioned substances. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1is the crystal structure of the target compound 3 prepared in Example 1 of the present application.

[0026] Figure 2 is the crystal packing diagram of the target compound 3 prepared in Example 1 of the present application.

[0027] Figure 3 is the fluorescence spectrum of the target compound 3 (probe 3) titrated with different cations, respectively.

[0028] Figure 4 is Cu 2+ The fluorescence titration curve of the target compound 3 (probe 3).

[0029] Figure 5 is the fitting curve of Figure 4

[0030] Figure 6 is the fluorescence emission spectrum of S 2- The fluorescence titration curve of 3-Cu 2+

[0031] Figure 7 is the fluorescence spectrum of the probe 3-Cu 2+ in application example 3 for recognition of different anions.

[0032] Figure 8 is the fluorescence emission spectrum of the target compound 3 (probe 3) and 3-trifluoroacetic acid in application example 5 combined with trifluoroacetic acid and triethylamine, respectively.

[0033] Figure 9 is the fluorescence emission spectrum of the target compound 3 (probe 3) in application example 7 under 302 nm light steady state and after heating.

[0034] Figure 10 is the fluorescence titration fitting curve of the probe 3 in application example 8 after irradiation with 302 nm light source for 90 min for Cu 2+ . DETAILED DESCRIPTION

[0035] A series of novel salicylic hydrazide derivatives containing pyrazole groups are designed and synthesized in the present application, and their fluorescence properties in various solutions are studied. The research results show that the series of compounds have good detection effect on Cu 2+ , S 2- , trifluoroacetic acid, and triethylamine, and the irradiation of ultraviolet light can enhance the fluorescence quantum yield of part of the compounds to improve the detection sensitivity, thereby realizing the light control of the fluorescence probe.

[0036] The following application examples can make the professional technical personnel more clearly understand the present application, but do not limit the present application in any way. Although the present application only lists compound 3 (probe 3), R​​1 ~R 4 respectively, have no effect on the detection effect. The solvents used in the fluorescence detection method include but are not limited to the following solvents (dichloromethane, acetonitrile, tetrahydrofuran and water).

[0037] The target compound emits blue-green light with a wavelength range of 400-550 nm under excitation of a 320 nm light source in an acetonitrile solution (5×10 -5 mol) can emit blue-green light with a wavelength range of 400-550 nm under excitation of a 320 nm light source, and after adding a copper ion aqueous solution, fluorescence quenching can be achieved, and the quenching effect linearly increases with the increase of the concentration of copper ions, and the detection limit is 0.24 μM. While the target compound and copper ions form a complex 3-Cu 2+ The detection of sulfur ions can be achieved, and the detection limit is 1.86 μM. At the same time, this series of fluorescent probes can realize the detection of trifluoroacetic acid in dichloromethane, chloroform, tetrahydrofuran, acetonitrile, cyclohexane, methanol, ethanol or isopropanol, that is, in a 5×10 -5 mol of probe solution, slow dropwise addition of trifluoroacetic acid (1-2 μL) can quickly achieve fluorescence quenching of the system, and the addition of triethylamine again can restore the fluorescence emission intensity of the system. The test method refers to the method reported by Nakorn Niamnont et al. in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 279 (2022) 121382 and the method reported by Kamaljit Singh et al. in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 290 (2023) 122239.

[0038] The solvent system of the probe (the solvent can be acetonitrile and dichloromethane, etc.) is irradiated by a 302 nm light source to the light steady state, which can increase the fluorescence intensity and the quantum yield, thereby providing a premise for further improving the detection sensitivity of this series of probes, and also realizing the light control of the fluorescent probe. This series of fluorescent probes can also be used as fluorescent dyes, biosensors, etc.

[0039] It is worth noting that, on the basis of the present application (E) 2-hydroxy-N'-((1-methyl-1H-pyrazol-3-yl) methylene) benzohydrazide (target compound 3), when the pyrazole part connected with acylhydrazone is changed in its linkage site or replaced by other five-membered rings, the fluorescence emission properties of the molecule are obviously decreased, and it does not have a probe effect. Therefore, the present application introduces (E) 2-hydroxy-N'-((1-methyl-1H-pyrazol-4-yl) methylene) benzohydrazide (compound 4), (E) 2-hydroxy-N'-((1-methyl-1H-pyrazol-5-yl) methylene) benzohydrazide (compound 5), and (E) N'-(cyclopentylmethylene)-2-hydroxybenzohydrazide (compound 6) for a total of 3 comparative examples, proving the outstanding performance of the target compound 3 as a probe.

[0040]

[0041] Example 1

[0042] The synthesis route of the target compound 3 is shown below, and the synthesis and purification methods can use the commonly used synthesis methods in the art.

[0043]

[0044] Compound 1, i.e., methyl salicylate (1.52 g, 10 mmol), was added to 15 mL of ethanol, and 85% hydrazine hydrate (2 g, 50 mmol) was slowly added dropwise while stirring, followed by warming to 60°C. The reaction progress was detected by thin layer chromatography, and the reaction was stopped after 4 hours of reflux, and the system was cooled to room temperature. The solvent was removed by reduced pressure distillation, and the product was purified by column chromatography (developing agent: V (ethyl acetate) : V (petroleum ether) = 1:1) to obtain intermediate 2, i.e., salicylic hydrazide 1.35 g, with a yield of 89%.

[0045] Compound 2 (0.45 g, 3 mmol) was added to 20 mL of ethanol, and 1-methyl-1H-pyrazole-3-carboxaldehyde (0.5 g, 4.5 mmol) was added dropwise. The system was warmed to 60°C, and the reaction was carried out for 6 hours. The system was cooled to room temperature, and a solid was washed out. The target compound 3 was obtained by recrystallization from ethanol, with a weight of 0.56 g and a yield of 76%. 1 H NMR (500 MHz, DMSO) δ 11.86 (s, 1H), 11.77 (s, 1H), 8.43 (s, 1H), 7.86 (s, 1H), 7.78 (s, 1H), 7.44 (s, 1H), 6.96 (s, 2H), 6.63 (s, 1H), 3.89 (s, 3H); 13 C NMR (126 MHz, DMSO) δ 165.33,

[0046] 159.66, 147.61, 143.90, 134.27, 133.14, 128.81, 119.35, 117.76, 116.27, 103.70, 39.27; HRMS calcd for C 12 H 13 N4O2[M+H] + 245.1033; found 245.1039; C 12 H 12 N4O2(244.10) calculated. C, 59.01; H, 4.95; N, 22.94; found C 58.45, H 4.82, N 21.37.

[0047] The structure of the synthesized target compound is proved by X single crystal diffraction of the target compound, Figure 1 and 2 are the single crystal structure and unit cell diagram of the target compound 3, respectively.

[0048] Comparative Example 1

[0049] The synthesis route of compound 4 is shown below, and the synthesis and purification methods can use the synthesis methods commonly used in the art. Compound 1, i.e. methyl salicylate (1.52 g, 10 mmol), was added to 15 mL of ethanol, and 85% hydrazine hydrate (2 g, 50 mmol) was slowly added dropwise under stirring, and then the temperature was raised to 60°C. The reaction progress was detected by thin layer chromatography, and the reaction was stopped after 4 hours of reflux, and the temperature was lowered to room temperature. The solvent was concentrated by distillation under reduced pressure, and the product was purified by column chromatography (developing agent: V (ethyl acetate): V (petroleum ether) = 1:1) to obtain intermediate 2, i.e. salicylic hydrazide 1.35 g, with a yield of 89%.

[0050] Compound 2 (0.45 g, 3 mmol) was added to 20 mL of ethanol, and 1-methyl-1H-pyrazole-4-carboxaldehyde (0.5 g, 4.5 mmol) was added dropwise. The temperature was raised to 60°C, and the reaction was carried out for 6 hours. The system was cooled to room temperature, and a solid was washed out. Ethanol recrystallization was carried out to obtain the target compound 4, which weighed 0.48 g, with a yield of 66%. 1 H NMR (500 MHz, DMSO) δ 12.01 (s, 1H), 11.63 (s, 1H), 8.36 (s, 1H), 8.15 (s, 1H), 7.87 (dd, J = 7.8, 1.2 Hz, 1H), 7.79 (s, 1H), 7.46 - 7.38 (m, 1H), 6.99 - 6.91 (m, 2H), 3.88 (s, 3H); 13C NMR (126 MHz, DMSO) d 165.04, 159.79, 143.10, 138.26, 134.21, 131.63, 128.68, 119.30, 117.77, 116.07, 39.19; HRMS calcd for C 12 H 13 N4O2[M+H] + 245.1033, found 245.1036; C 12 H 12 N4O2(244.10) calculated. C, 59.01 ; H, 4.95; N, 22.94; found C 58.04, H 4.79, N 21.84.

[0051] Comparative Example 2

[0052] Compound 1, methyl salicylate (1.52 g, 10 mmol) was added to 15 mL of ethanol, 85% hydrazine hydrate (2 g, 50 mmol) was added dropwise under stirring and then the temperature was raised to 60°C, the progress of the reaction was monitored by thin layer chromatography, after 4 hours of reflux the reaction was stopped and the temperature was lowered to room temperature, the solvent was removed by distillation under reduced pressure, the product was purified by column chromatography (eluent: V(ethyl acetate):V(petroleum ether) = 1 :1 ) obtaining intermediate 2, salicylic hydrazide 1.35 g, yield 89%.

[0053] Compound 2 (0.45 g, 3 mmol) was added to 20 mL of ethanol, 1 -methyl-1 H-pyrazole-5- carboxaldehyde (0.5 g, 4.5 mmol) was added dropwise, the temperature was raised to 60°C, the reaction was left for 6 hours, the system was lowered to room temperature, a solid was washed out, the target compound 5 was obtained by recrystallization from ethanol, weighing 0.40 g, yield 55%. 1 H NMR (500 MHz, DMSO) d 11.88 (s, 1 H), 11.75 (s, 1 H), 8.55 (s, 1 H), 7.88 (d, J = 7.7 Hz, 1 H), 7.50 (t, J = 7.0 Hz, 1 H), 7.45 (dd, J = 11.3, 4.1 Hz, 1 H), 6.98 (dd, J = 13.7, 7.7 Hz, 2H), 6.69 (d, J = 1.5 Hz, 1 H), 4.06 (s, 3H); 13 C NMR (126 MHz, DMSO) d 165.12, 159.35, 139.05, 138.74, 136.89, 134.37, 129.09, 119.50, 117.76, 116.41, 108.19, 38.77; HRMS calcd for C 12 H 13 N4O2[M+H]+ 245.1033, found 245.1033; C 12 H 12 N4O2(244.10) calculated.C,59.01;H,4.95;N,22.94;found C 58.73,H 4.82,N 21.21.

[0054] Comparative Example 3

[0055] Compound 1, methyl salicylate (1.52 g, 10 mmol) was added to 15 mL of ethanol, 85% hydrazine hydrate (2 g, 50 mmol) was added dropwise under stirring, then the temperature was raised to 60°C, the reaction progress was monitored by thin layer chromatography, after 4 hours of reflux the reaction was stopped and the temperature was lowered to room temperature, the solvent was removed by distillation under reduced pressure, the product was purified by column chromatography (eluent: V (ethyl acetate): V (petroleum ether) = 1:1) to obtain intermediate 2, salicylic hydrazide 1.35 g, in 89% yield.

[0056] Compound 2 (0.45 g, 3 mmol) was added to 20 mL of ethanol, cyclopentanecarboxaldehyde (0.44 g, 4.5 mmol) was added dropwise, the temperature was raised to 60°C, the reaction was carried out for 5 hours, the system was then lowered to room temperature, a solid was washed out, the target compound 6 was obtained by recrystallization from ethanol, weighing 0.41 g, in 59% yield. 1 H NMR (500 MHz, DMSO) d 11.98 (s, 1H), 11.46 (s, 1H), 7.83 (d, J = 7.6 Hz, 1H), 7.71 (d, J = 6.3 Hz, 1H), 7.42 (t, J = 7.7 Hz, 1H), 6.93 (dd, J = 13.9, 7.7 Hz, 2H), 2.76 - 2.67 (m, 1H), 1.86 - 1.79 (m, 2H), 1.66 - 1.53 (m, 6H);13C NMR (126 MHz, DMSO) d 165.18, 159.83, 157.25, 134.16, 128.65, 119.24, 117.82, 115.91, 42.66, 30.50, 25.50; HRMS calcd for C 13 H 17 N2O2[M+H]+233.1285, found 233.1285; C 13 H 16 N2O2(232.12) calculated.C 67.22,H 6.94,N 12.06;found C 66.52,H 7.49,N 10.14.

[0057] Application Example 1

[0058] The concentration to be prepared is 1×10 -3 Simultaneously, prepare 1×10⁻⁶ mol of acetonitrile stock solution for probe 3. -3 mol of the analyte ion Li + Na + K + Ag + Mg 2+ Ni 2+ Mn 2+ Sn 2+ Fe 2+ Ga 2+ and Cu 2+ There are 11 types of aqueous stock solutions.

[0059] Add 100 μL of acetonitrile stock solution of probe 3 to a fluorescent cuvette and dilute to 2 mL. Measure the fluorescence emission spectrum using 320 nm as the excitation source and record the spectrum. A distinct fluorescence emission peak is observed near 450 nm. Then, add 100 μL of the analyte ion Li₂. + Take the stock solution, shake until homogeneous, let stand for 3 minutes, and record the fluorescence spectrum again under the same conditions to compare the difference with the original spectrum.

[0060] Replace the remaining analyte ions and repeat the above steps sequentially to obtain the fluorescence spectra of probe 3 titrated with different cations (analyte ions), such as... Figure 3 As shown, the titration results indicate that only Cu 2+ Fluorescence quenching of probe 3 was achieved. Therefore, this indicates that probe 3 can quench the fluorescence of Cu. 2+ Perform specific fluorescence quenching recognition (e.g.) Figure 3 It showed no significant response to other cations.

[0061] Add 100 μL of the acetonitrile stock solution of probe 3 to a fluorescent cuvette and dilute to 2 mL. Prepare seven aliquots, and then add 0, 20, 40, 60, 80, 100, and 150 μL of the analyte Cu to each aliquot respectively. 2+ The stock solution was shaken until homogeneous, allowed to stand for 3 minutes, and fluorescence emission spectra were measured using 320 nm as the excitation source to obtain Cu concentrations at different concentrations. 2+ The fluorescence titration curve of probe 3 is as follows: Figure 4 As shown, for Figure 4 The fitting was performed, and the resulting fitted curve is shown below. Figure 5 The detection limit was calculated to be 0.24 μL using the formula (detection limit = 3 × systematic error / detector sensitivity).

[0062] Application Example 2

[0063] The acetonitrile stock solution of probe 3 was replaced by the dichloromethane stock solution of probe 3, and other processes were the same as in Application Example 1. The detection results showed that probe 3 also exhibited specific recognition for Cu 2+ in the dichloromethane solution. The detection limit LOD value was 0.31 μL.

[0064] Application Example 3

[0065] The acetonitrile stock solution of probe 3 with a concentration of 1×10 -3 mol and the Cu -3 aqueous solution stock solution with a concentration of 1×10 2+ mol were prepared. 100 μL of the acetonitrile stock solution of probe 3 and 100 μL of the Cu 2+ aqueous solution stock solution were added into a 1.5 mL centrifuge tube, shaken well, transferred into a fluorescence cuvette, diluted to 2 mL, and 8 portions were prepared. 0, 20, 40, 60, 80, 100, 120, and 140 μL of Na2S aqueous solution with a concentration of 1×10 -3 mol were added dropwise into each portion, respectively. The fluorescence emission spectrum was recorded with 320 nm as the excitation light source, and the results are shown in Figure 6 The fluorescence intensity gradually recovered. The detection limit was calculated to be 1.86 μL using the detection limit calculation formula (detection limit = 3×system error / slope).

[0066] Using the same method above, several other common anions OH - , CO3 2- , and F - , Cl - , Br - , and the like were detected, and the experimental results are shown in Figure 7 The results showed that there was no fluorescence response to these several anions.

[0067] Application Example 4

[0068] The acetonitrile stock solution of probe 3 was replaced by the tetrahydrofuran stock solution of probe 3, and other processes were the same as in Application Example 3. The results showed that changing the solvent to tetrahydrofuran could also achieve the detection of S 2+ using probe 3-Cu 2- . The detection limit was calculated to be 2.35 μL using the detection limit calculation formula (detection limit = 3×system error / slope).

[0069] Application Example 5

[0070] The acetonitrile stock solution of probe 3 with a concentration of 1×10 -3mol of probe 3 in acetonitrile, diluted to 2 mL, and the fluorescence spectrum was recorded with 320 nm as the excitation light source. Then 5 μL of trifluoroacetic acid (TFA) was added dropwise, and the fluorescence emission spectrum was recorded. Next, 10 μL of triethylamine (TEA) was added, and the fluorescence emission spectrum was recorded. Finally, the resulting fluorescence emission spectrum is shown in Figure 8 As can be seen from Figure 8 , the fluorescence emission intensity of the probe 3 system decreased upon addition of trifluoroacetic acid, and the fluorescence emission intensity of the probe 3 system increased upon addition of triethylamine, indicating that probe 3 can effectively and specifically recognize trifluoroacetic acid and triethylamine, respectively.

[0071] Application Example 6

[0072] The acetonitrile stock solution of probe 3 was replaced with a tetrahydrofuran stock solution of probe 3, and the other procedures were the same as in Application Example 5. The results showed that when the solvent was changed to tetrahydrofuran, probe 3 could still recognize trifluoroacetic acid and triethylamine.

[0073] Application Example 7

[0074] A 1 x 10 -3 mol of probe 3 in acetonitrile was prepared, and the sample was diluted to 2 mL. The fluorescence spectrum was recorded with 320 nm as the excitation light source. The sample was irradiated with 302 nm ultraviolet light for 30 min, and the fluorescence emission spectrum was recorded. The sample was irradiated with 302 nm ultraviolet light for a total of 90 min, and the fluorescence emission spectrum was recorded. The sample that had been irradiated for 90 min was heated to 50-60°C, and the fluorescence emission spectrum was recorded. Finally, the resulting fluorescence emission spectrum is shown in Figure 9 As can be seen from Figure 9 , irradiation with 302 nm ultraviolet light can enhance the fluorescence emission intensity of probe 3, and heating can restore the fluorescence emission intensity.

[0075] The reason why irradiation with 302 nm ultraviolet light can enhance the fluorescence emission intensity of probe 3 is that irradiation with 302 nm ultraviolet light can achieve a configuration transformation of the compound (E form → Z form), as follows:

[0076]

[0077] Application Example 8

[0078] 100 μL of an acetonitrile stock solution of probe 3 was added to a fluorescence cuvette and diluted to 2 mL. The sample was irradiated with 302 nm ultraviolet light for 90 min, and then 0, 20, 40, 60, 80, 100, and 150 μL of a Cu 2+ stock solution to be tested was added dropwise, and the mixture was shaken until uniform. After standing for 3 min, the fluorescence emission spectrum was determined with 320 nm as the excitation light source, and the fluorescence titration curve was obtained. After fitting, the fitting curve is shown in Figure 10As shown, after the probe 3 solution system was irradiated by a 302 nm light source for 90 minutes, the detection limit of the probe for Cu 2+ was 0.18 μM, which was obviously improved compared with the initial state of 0.24 μM.

[0079] Comparative application example 1

[0080] The compounds 4, 5, and 6 in the present application comparative example 1, comparative example 2, and comparative example 3 were used in turn for fluorescence titration experiments on Cu 2+ The process was the same as in application example 1, and the titration results showed that the fluorescence response was not obvious, so the compounds 4, 5, and 6 had poor detection effects on Cu 2+ .

[0081] Comparative application example 2

[0082] The fluorescence probes 4, 5, and 6 in the present application comparative example 1, comparative example 2, and comparative example 3 were used in turn for fluorescence titration experiments on S 2- The process was the same as in application example 3, and the titration results showed that the fluorescence response was not obvious, so the compounds 4, 5, and 6 had poor detection effects on S 2- .

[0083] Comparative application example 3

[0084] The fluorescence probes 4, 5, and 6 in the present application comparative example 1, comparative example 2, and comparative example 3 were used in turn for fluorescence titration experiments on trifluoroacetic acid and triethylamine. The process was the same as in application example 5, and the titration results showed that the fluorescence response was not obvious, so the compounds 4, 5, and 6 had poor detection effects on trifluoroacetic acid and triethylamine.

Claims

1. A salicylic hydrazide derivative having a pyrazole group having a light switching property, characterized by, It has the following structure: Wherein, R 1 - R 4 is a hydrogen atom.

2. The method of claim 1, wherein the salicylichydrazide derivative is prepared by the reaction of a compound of the formula (2) with hydrazine hydrate in the presence of a base. Comprise: (1) the preparation of compound 2 by substitution reaction of compound 1 with hydrazine hydrate, (2) the preparation of target compound by the reaction of compound 2 with 1-methyl-1H-pyrazole-3-formaldehyde, 3. The method of claim 2, wherein, In step (1) and step (2), the reaction is carried out in the presence of organic solvent ethanol.

4. The method of claim 2, wherein, In step (1), the temperature of substitution reaction is 60±5℃, and the reaction time is 4 hours.

5. The method of claim 2, wherein, In step (1), the molar ratio of compound 1 to hydrazine hydrate is 1:

5.

6. The method of claim 2, wherein, In step (2), the reaction temperature is 60-75℃, and the reaction time is 6 hours.

7. The method of claim 2, wherein, In step (2), the molar ratio of reactant 2 to 1-methyl-1H-pyrazole-3-formaldehyde is 1:1.

5.

8. Use of the salicylichydrazide derivative according to claim 1 as a fluorescent probe for non-disease diagnosis and treatment, characterized in that, The salicylic hydrazide derivative can recognize copper ions, sulfur ions, trifluoroacetic acid or triethylamine.

9. Use according to claim 8, characterized in that, The salicylic hydrazide derivative can emit fluorescence under 302nm ultraviolet light.

Images