A cyanine-like infrared fluorescent probe and its synthesis method and application

Abstract

The present invention discloses a cyanine-like infrared fluorescent probe and its synthesis method and application, which belongs to the field of organic small molecule ratiometric fluorescent probes. The cyanine-like infrared fluorescent probe has the molecular formula of C 27 H 25 ClN2O6, labeled FS-C1; this fluorescent probe has excellent solubility in neutral polarity solutions and is equally miscible with aqueous solutions of biogenic amines. Using neutral polarity solvents as a medium, it can produce a rapid, highly sensitive, and intense sensing process under very mild conditions. When organic amines are present in the environment, the fluorescent probe rapidly reacts with them, producing a visible color change, changing the solution from dark blue to pale yellow. This enables real-time, quantitative, micromolar-level monitoring of organic amines in spoiled foods. This type of cyanine infrared fluorescent probe can be applied to the visual detection of organic amines and the development of related test strips. It can also be used in the safety assessment of organic amines in spoiled foods, and has promising application prospects in food safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic small molecule ratiometric fluorescent probes, and in particular relates to a cyanine-like infrared fluorescent probe and a synthesis method and application thereof. Background Art

[0002] Organic amines are the most consumed industrial chemicals in the agrochemical, pharmaceutical, automotive chemical, and cosmetics industries. Most are highly toxic, persistent, and bioaccumulative, and excessive exposure to volatile organic amine vapors can lead to serious health problems. Furthermore, biogenic amines primarily serve as indicators of food spoilage caused by fermentation or microbial activity, leading to serious toxicological risks and food poisoning. There is an urgent need to develop sensitive amine detection methods for use in public health, food safety, environmental monitoring, and other related areas.

[0003] In recent years, methods for detecting amines have become increasingly diverse. Currently, conventional methods for measuring amine compounds in the environment include spectrophotometry, ion chromatography, gas chromatography, and various sensor technologies. Among these, reaction-based fluorescent probes offer advantages such as simple operation, low cost, strong specificity, and high sensitivity, making them a powerful tool for monitoring amines. Consequently, reaction-based fluorescent probes for detecting organic amines have garnered significant attention.

[0004] Meng Y's team developed a fluorescent probe that can detect monomethylamine, cyclohexylamine, diethylamine, triethylamine, and propylamine vapor in dichloromethane. The probe (10 mM) reacts with propylamine vapor and has a good linear relationship in the concentration range of 0 to 175 ppm. The detection limit can reach 3.82 ppm. The reaction is sensitive and can change rapidly within 1 minute. Wang L's team developed a probe PPCy-1. When the probe is dissolved in chloroform, the detection limits (LODs) of spermine, spermidine, corpse and putrescine are 0.066 μM, 0.043 μM, 0.229 μM and 0.179 μM, respectively. Basavaraja D's team developed a probe Pyr3,6. When it is dissolved in dichloromethane and reacts with amine solution, the fluorescence is gradually quenched and disappears within 3 minutes. If the amine is present in gaseous form, the reaction rate increases, resulting in calculated detection limits of 14.9 μM for putrescine and 33.2 μM for triethylamine. The Virginia Valderrey team developed a probe that can be activated by light at the desired moment when dissolved in dichloromethane. Its sensitivity allows detection of amines in solution at concentrations as low as 10 μM. Furthermore, by immobilizing DAE on paper, biogenic amines, such as cadaverine, can be detected in the gas phase at concentrations above the 12 ppbv threshold within 30 seconds.

[0005] However, most fluorescent probes currently available for detecting organic amines produced by food spoilage can only detect biogenic amines in aqueous solutions, with a few capable of detecting them in organic solvents. Therefore, designing an infrared fluorescent probe capable of detecting biogenic amines in neutral-polarity solutions has important practical significance and promising application prospects. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide a cyanine-like infrared fluorescent probe and its synthesis method and application. This infrared fluorescent probe can use a neutral polarity solvent as a medium to selectively detect trace organic amines produced during food spoilage, thereby realizing visual and highly sensitive detection of trace organic amines.

[0007] The technical solutions of the present invention are as follows:

[0008] One of the purposes of the present invention is to provide a cyanine-like infrared fluorescent probe, wherein the infrared fluorescent probe is labeled as FS-C1, and the molecular formula is C 27 H 25 ClN2O6, chemical structure is shown in Ⅰ:

[0009]

[0010] A second object of the present invention is to provide a method for synthesizing a cyanine-like infrared fluorescent probe, comprising the following steps:

[0011] (1) Cesium carbonate and 1,8-naphtholactam were dissolved in acetonitrile, iodomethane was added dropwise, and the mixture was stirred at room temperature under an argon atmosphere. The solvent was removed by rotary evaporation, and a bright yellow powder was obtained after separation and purification using petroleum ether: ethyl acetate = 23:1, which is compound 1. The reaction process is as follows:

[0012]

[0013] (2) Compound 1 obtained in step 1 was dissolved in anhydrous THF at 0°C, methylmagnesium chloride was added dropwise and stirred, and then refluxed in an oil bath under argon atmosphere. After the reaction was completed, it was placed in an ice bath and the temperature was lowered to 0°C. A small amount of water was added to quench the reaction. Perchloric acid was then added to the reaction mixture and stirred thoroughly to obtain a yellow-green solution. The solution was added to ice water, vacuum filtered, and dried to obtain a green powder, namely compound 2. The reaction process is as follows:

[0014]

[0015] (3) Compound 2, anhydrous sodium acetate, and 7-(diethylamino)coumarin-3-carboxaldehyde were dissolved in anhydrous ethanol. The mixture was refluxed overnight under an argon atmosphere. The solvent was dried and purified by silica gel column chromatography using a mixture of dichloromethane and methanol (10:1) to obtain the infrared fluorescent probe FS-C1. The reaction process is as follows:

[0016]

[0017] Furthermore, in step (1), the molar ratio of 1,8-naphtholactam, cesium carbonate and methyl iodide is 1:1.5:1.2.

[0018] Furthermore, in the step (1), the mixture is stirred for 3-5 hours under an argon atmosphere.

[0019] Furthermore, the separation and purification in step (1) uses a petroleum ether / ethyl acetate mixed solvent.

[0020] Furthermore, petroleum ether:ethyl acetate=23:1.

[0021] Furthermore, in step (2), the molar ratio of compound 1 to methylmagnesium chloride is 1:4.5.

[0022] Furthermore, in the step (2), the reflux temperature in the oil bath is 50-70° C., and the reflux time is 1-3 h.

[0023] Furthermore, in step (3), the molar ratio of compound 2, 3-(diethylamino)coumarin-3-formaldehyde, and anhydrous sodium acetate is 1:1:0.1.

[0024] Furthermore, the overnight reflux temperature in step (3) is 75-85°C.

[0025] Furthermore, the separation and purification in step (3) is performed by column chromatography.

[0026] Furthermore, the chromatography eluent in the column chromatography separation is a dichloromethane / methanol mixed solution, and the volume ratio of the two is 10:1.

[0027] The third object of the present invention is to provide a cyanine-like infrared fluorescent probe for use in the high-sensitivity detection of trace organic total amines.

[0028] Furthermore, when organic amines are present in the organic solvent, the infrared fluorescent probe FS-C1 can respond quickly and react with the organic amines to produce an obvious color change.

[0029] Furthermore, as the reaction with the organic amine proceeds, the color of the infrared fluorescent probe FS-C1 solution changes from dark blue to yellow.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention designs a cyanine-like infrared fluorescent probe, FS-C1, which is an ideal sensor for the rapid and sensitive detection of organic amines. This infrared fluorescent probe dissolves well in neutral polarity solutions and is miscible with aqueous solutions of biogenic amines. Using neutral polarity solvents as a medium, it reacts with organic amines under very mild conditions, resulting in a rapid (30 seconds) and highly sensitive sensing process. This enables real-time, quantitative detection of organic amines, demonstrating its potential for detecting biogenic amines during food spoilage.

[0032] 2. The cyanine-like infrared fluorescent probe FS-C1 synthesized in the present invention can directly detect biogenic amines. When reacting with organic amines, the color of the fluorescent probe solution changes from the original dark blue to yellow. The color change is significant, and biogenic amines can be visually detected with the naked eye. It has broad application prospects in the development of visual detection and test strips, and can be used for the safety assessment of organic amines in spoiled food.

[0033] 3. Compared with existing fluorescent probe technologies, the synthesis method of the cyanine-like infrared fluorescent probe FS-C1 in the present invention is simple, the synthesis process is rapid, the operation steps are simple, and the yield is considerable. It is environmentally friendly. The synthesized cyanine-like infrared fluorescent probe FS-C1 can achieve micromolar level monitoring of organic amines and has good development prospects in the field of food safety.

[0034] Reference numerals

[0035] Figure 1 This is the H NMR spectrum of the cyanine-like infrared fluorescent probe FS-C1 synthesized in Example 1 of the present invention;

[0036] Figure 2 This is a broken line graph showing the fluorescence intensity at 483 nm of actual shrimp samples detected on different days using the cyanine-like infrared fluorescent probe FS-C1 in Example 2 of the present invention:

[0037] Figure 3 The UV spectrum characteristic diagram and fluorescence spectrum characteristic diagram of the reaction between the cyanine-like infrared fluorescent probe FS-C1 and 10eq of ethylenediamine in different solvents in the performance test of the present invention are shown in FIG. Figure 3 A is the ultraviolet spectrum, Figure 3 B is the fluorescence spectrum (excitation light is 420nm), Figure 3 C is a bar graph of fluorescence intensity of different solvents at 483 nm;

[0038] Figure 4The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and ethylenediamine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 4 The excitation light for the fluorescence spectrum in B is 420 nm;

[0039] Figure 5 The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and diethylenetriamine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 5 The excitation light for the fluorescence spectrum in B is 420 nm;

[0040] Figure 6 The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and n-hexylamine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 6 The excitation light for the fluorescence spectrum in B is 420 nm;

[0041] Figure 7 The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and putrescine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 7 The excitation light for the fluorescence spectrum in B is 420 nm;

[0042] Figure 8 The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and spermine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 8 The excitation light for the fluorescence spectrum in B is 420 nm;

[0043] Figure 9 The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and tyramine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 9 The excitation light for the fluorescence spectrum in B is 420 nm;

[0044] Figure 10 The ultraviolet spectrum characteristic diagram (A), fluorescence spectrum characteristic diagram (B), and linear relationship diagram (C) between fluorescence intensity (483 nm) and cadaverine concentration of the cyanine-like infrared fluorescent probe FS-C1 in the performance test of the present invention are shown. Figure 10 The excitation light for the fluorescence spectrum in B is 420 nm; DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and preferred embodiments. The given embodiments are only for illustrating the present invention, rather than for limiting the scope of the present invention.

[0046] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0047] The quantitative tests in the following examples were repeated three times, and the results were averaged.

[0048] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0049] The drying solvents used in the following examples were all molecular sieves 4A (sodium-type A molecular sieve) or molecular sieves 3A (potassium-type A molecular sieve);

[0050] 1 H spectra were recorded on a JEOL ECZ600S (600 MHz) spectrometer using CDCl3 or CD3OD as solvent;

[0051] Upfield chemical shifts are reported in parts per million based on internal TMS (trimethylsilane) reference data;

[0052] The coupling constant (J) is expressed in Hertz (Hz), and the spin multiple states are represented by s (singlet), d (doublet), t (triplet), and m (multiplet);

[0053] Column chromatography used thick-walled glass columns and silica gel (300-400 mesh); thin-layer chromatography (TLC) was performed using commercially available 0.25 mm silica gel plates, and UV light was used for visualization;

[0054] The UV absorption spectra of the solutions were obtained using a Shimadzu UV-1900 UV-visible-near-infrared spectrophotometer;

[0055] Fluorescence spectra were measured using a Spectrofluorometer FS5 fluorescence spectrometer;

[0056] Mass spectra were recorded on a ThermoFisher high-performance liquid chromatography-mass spectrometry instrument;

[0057] Example 1

[0058] This embodiment provides a cyanine-like infrared fluorescent probe, the synthesis method of which includes the following steps:

[0059] S1. Dissolve cesium carbonate (0.48 g, 1.5 mmol) and 1,8-naphtholactam (0.17 g, 1 mmol) in 8 mL of acetonitrile, add iodomethane (0.124 mL, 2 mmol) dropwise, and stir at room temperature under argon for 4 h. Remove the solvent, separate, and purify to obtain a bright yellow powder, Compound 1. The preparation process is as follows:

[0060]

[0061] S2. Compound 1 (0.182 g, 1 mmol) obtained in step 1 was dissolved in anhydrous THF at 0°C, and methylmagnesium chloride (1.5 mL, 4.5 mmol) was added dropwise and stirred for 10 min. The mixture was refluxed in an oil bath at 60°C under an argon atmosphere for 2 h. After the reaction, the mixture was placed in an ice bath at 0°C. When the temperature dropped to 0°C, a small amount of water (0.5 mL) was added to quench the reaction. Perchloric acid (60%, 0.6 mL) was then added to the reaction mixture and stirred thoroughly. The yellow-green solution was added to ice water (90 mL), vacuum filtered, and dried to obtain a green powder, namely compound 2. The preparation process is as follows:

[0062]

[0063] S3. Compound 2, 7-(diethylamino)coumarin-3-carboxaldehyde, and anhydrous sodium acetate were added to an appropriate amount of anhydrous ethanol in a molar ratio of 1:1:0.1. The mixture was refluxed overnight at 80°C under an argon atmosphere. The solvent was evaporated, and the mixture was purified by silica gel column chromatography to obtain the product probe FS-C1, wherein the chromatography eluent was dichloromethane:methanol = 10:1. The synthesis process is as follows:

[0064]

[0065] S4. The cyanine infrared fluorescent probe FS-C1 was analyzed by nuclear magnetic resonance hydrogen spectrum. The spectrum is shown in the attached figure. Figure 1 shown.

[0066] Among them, this synthesis method can also adjust S1 to be stirred for 3 hours or 5 hours under argon atmosphere, adjust S2 to be refluxed in a 50°C oil bath for 3 hours or in a 70°C oil bath for 1 hour, and adjust S3 to be refluxed overnight at 75°C or 85°C according to actual operating conditions.

[0067] Example 2

[0068] This example uses the cyanine-like infrared fluorescent probe in Example 1 to detect organic amines in actual shrimp samples, including the following steps:

[0069] S1. Select fresh live shrimp as samples, cook the shrimp and place them at room temperature, and dilute the shrimp pieces on the first, third, and fifth days;

[0070] S2. Under excitation light of 420 nm, measure the fluorescence spectrum of cyanine-like infrared fluorescent probe FS-C1 (10 μM) with different volumes (0-60 μL) of cooked shrimp juice added, record the maximum fluorescence intensity at the peak, and draw a line graph based on the obtained data.

[0071] As attached Figure 2 As shown, over time, shrimp meat, under the action of microorganisms, produces increasing amounts of amines, leading to a rise in amine concentrations in the sample. Binding of the FS-C1 probe to organic amines results in an increase in fluorescence at 483 nm. In summary, the binding of the FS-C1 probe to organic amines can indirectly reflect the tendency of food spoilage, making the fluorescent probe FS-C1 suitable for evaluating spoiled food.

[0072] Performance Testing

[0073] 1. Ultraviolet spectrum test of the cyanine-like infrared fluorescent probe FS-C1 in Example 1 in solvents of different polarities and dielectric constants with 10eq of ethylenediamine:

[0074] S1. Four solvents with different polarities and dielectric constants were screened out based on the two conditions of solvent polarity and dielectric constant: petroleum ether, tetrahydrofuran, water, N,N-dimethylformamide, and acetonitrile.

[0075] S2. The probe FS-C1 obtained in Example 1 was dissolved in dimethyl sulfoxide, placed in four solvents: petroleum ether, tetrahydrofuran, water, N,N-dimethylformamide, and acetonitrile, and the UV absorption spectrum after the reaction with 10 eq of ethylenediamine was measured.

[0076] As attached Figure 3 As shown in Figure A, the cyanine-like infrared fluorescent probe FS-C1 shows a maximum absorption value at 660 nm in the UV absorption spectrum. In acetonitrile solution, the initial absorption value of probe FS-C1 at 660 nm is the highest. At the same time, after adding 10 eq of ethylenediamine, the degree of change of probe FS-C1 in acetonitrile is obvious. Therefore, from the UV spectrum results, the probe has a better detection effect on amines in acetonitrile solvent than other tested solvents.

[0077] 2. Fluorescence spectrum test of the cyanine-like infrared fluorescent probe FS-C1 in Example 1 in solvents of different polarities and dielectric constants with 10eq of ethylenediamine:

[0078] S1. Four solvents with different polarities and dielectric constants were screened out based on the two conditions of solvent polarity and dielectric constant: petroleum ether, tetrahydrofuran, water, N,N-dimethylformamide, and acetonitrile.

[0079] S2. The cyanine-like infrared fluorescent probe FS-C1 obtained in Example 1 was dissolved in dimethyl sulfoxide and placed in four solvents: petroleum ether, tetrahydrofuran, water, N,N-dimethylformamide, and acetonitrile. The fluorescence spectrum after the reaction with 10 eq of ethylenediamine was measured, as well as a bar graph based on the maximum fluorescence value at 483 nm. The conditions of the fluorescence spectrometer were: λex = 420 nm / λem = 483 nm, Step: 1.00 nm, Dwell: 0.1 s, Repeats: 2, Bdw = 2.

[0080] As attached Figure 3 As shown in BC, from the fluorescence spectrum results, the detection effect of the probe on amines in acetonitrile solvent is better than that in other tested solvents, indicating that the probe has the best detection effect on 10eq ethylenediamine in acetonitrile solvent.

[0081] 3. Ultraviolet absorption spectrum test of the cyanine-like infrared fluorescent probe FS-C1 in Example 1 to different concentrations of ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, spermine, tyramine, and cadaverine:

[0082] S1. Dissolve the cyanine-like infrared fluorescent probe FS-C1 obtained in Example 1 in dimethyl sulfoxide, and add acetonitrile buffer solution to dilute it to a 10 μM probe buffer solution;

[0083] S2. Take several portions of the above solution and add ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, spermine, tyramine, and cadaverine solutions respectively to make their concentrations: 0-100 μM, 0-240 μM, 0-60 μM, 0-50 μM, 0-20 μM, 0-230 μM, and 0-300 μM, and then measure the ultraviolet absorption spectra of the cyanine-like infrared fluorescent probe FS-C1 after reacting with amines of different concentrations.

[0084] As attached Figure 4 A- Figure 10 As shown in Figure A, in the UV spectrum, the cyanine-like infrared fluorescent probe FS-C1 exhibits a maximum absorption at 660 nm. Upon interaction with ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, and spermine, the probe's absorption peak at 660 nm gradually decreases with increasing amine concentrations. Meanwhile, increasing concentrations of tyramine and cadaverine lead to a gradual increase in the absorption peak at 483 nm. Simultaneously, the solution color changes from dark blue to light yellow, demonstrating that the probe FS-C1 can intuitively detect biogenic amines with the naked eye.

[0085] 4. Fluorescence spectrum test of the cyanine-like infrared fluorescent probe FS-C1 in Example 1 to different concentrations of ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, spermine, tyramine, and cadaverine:

[0086] S1. Take several portions of buffer solution of cyanine-like infrared fluorescent probe FS-C1, and add ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, spermine, tyramine, and cadaverine solutions respectively to make their concentrations: 0-240 μM, 0-280 μM, 0-120 μM, 0-80 μM, 0-20 μM, 0-250 μM, and 0-160 μM, respectively. Under the condition of excitation light of 420 nm, measure the fluorescence spectra of cyanine-like infrared fluorescent probe FS-C1 after reaction with different concentrations of ethylenediamine, n-hexylamine, diethylenetriamine, 1,4-butanediamine, spermine, tyramine, and cadaverine, respectively. Among them, the conditions of the fluorescence spectrometer are: λex = 420 nm, Step: 1.00 nm, Dwell: 0.1 s, Repeats: 2, Bdw = 2.

[0087] like Figure 4 B- Figure 10 As shown in Figure B, the fluorescence spectrum of probe FS-C1 is consistent with that of the UV spectrum, displaying similar sensitivity and selectivity. When excited at 420 nm, the fluorescence of probe FS-C1 at 483 nm gradually increases with the addition of ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, and spermine; however, the fluorescence at 483 nm gradually decreases with the addition of tyramine and cadaverine.

[0088] from Figure 4 C- Figure 10 As can be seen from Figure C, the fluorescence intensity of the probe FS-C1 has a good linear relationship with the concentrations of ethylenediamine, n-hexylamine, diethylenetriamine, putrescine, spermine, tyramine, and cadaverine (linear correlation coefficient R 2 =0.9937, R 2 =0.9925, R 2 =0.9903, R 2 =0.9940, R 2 =0.9965, R 2 =0.9986, R 2 =0.9906), so the probe FS-C1 can be used for quantitative detection of amines. The detection limits for ethylenediamine, n-hexylamine, diethylenetriamine, 1,4-butanediamine, spermine, tyramine, and cadaverine are calculated using the formula to be (0.012 μM, 0.033 μM, 0.0085 μM, 0.0369 μM, 0.17 μM, 0.0464 μM, and 0.027 μM).

[0089] The above results demonstrate that the probe exhibits excellent detection performance for all seven amines. Compared to biogenic amines, the fluorescence intensity change for FS-C1 is stronger and more pronounced for organic amines, with the fluorescence intensity for ethylenediamine, n-hexylamine, and diethylenetriamine increasing by approximately 100-fold, and for biogenic amines by several dozen-fold. The selectivity of FS-C1 for organic amines is related to the structure of the amine, with the probe being particularly sensitive to aliphatic amines such as ethylenediamine and n-hexylamine.

[0090] 5. Recovery test of the cyanine-like infrared fluorescent probe FS-C1 in Example 1 for detecting organic amines in actual samples:

[0091] S1. Cook fresh shrimp meat and let it sit for three days. Take the pieces and dilute them. Measure the fluorescence spectra of the cooked shrimp meat supernatant with different volumes (0-60 μL) and different concentrations of organic amines (putrescine, cadaverine, spermine, and tyramine) added to a 10 μM cyanine-like infrared fluorescent probe FS-C1 buffer solution under 420 nm excitation light.

[0092] S2. Obtain the fluorescence value from the fluorescence spectrum in S1, substitute it into the standard curve of different organic amines to calculate the content of the organic amine, and then calculate the spike recovery rate according to the spike recovery formula. The spike recovery formula is as follows:

[0093] P (recovery rate) = (amount of spiked sample - amount of sample measured) / spiked amount;

[0094] The calculation results are shown in Table 1:

[0095] Table 1 Spiked recovery of infrared fluorescent probe FS-B1 for detection of organic amines in actual samples

[0096]

[0097] As can be seen from Table 1, the average recoveries of different organic amines at different concentrations in the samples were all within the good range, indicating that the infrared fluorescent probe FS-B1 is effective in detecting organic amines in spoiled food.

[0098] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A cyanine-like infrared fluorescent probe, characterized in that: The infrared fluorescent probe is labeled FS-C1, and its molecular formula is C 27 H 25 ClN2O6, chemical structure is shown in Ⅰ:

2. A method for synthesizing a cyanine-like infrared fluorescent probe according to claim 1, characterized in that: Use the following steps: (1) Cesium carbonate and 1,8-naphtholactam were dissolved in acetonitrile, iodomethane was added dropwise, and the mixture was stirred at room temperature under an argon atmosphere. The solvent was removed by rotary evaporation, and a bright yellow powder was obtained by separation and purification, namely compound 1, whose structural formula is shown in II: (2) Compound 1 obtained in step 1 was dissolved in anhydrous tetrahydrofuran at 0°C, methylmagnesium chloride was added dropwise and stirred, and then refluxed in an oil bath under argon atmosphere. After the reaction, it was placed in an ice bath until the temperature dropped to 0°C, and a small amount of water was added to quench the reaction. Perchloric acid was then added to the reaction mixture and stirred thoroughly to obtain a yellow-green solution. The solution was added to ice water, vacuum filtered, and dried to obtain a green powder, namely compound 2, whose structural formula is shown in III: (3) Compound 2, anhydrous sodium acetate, and 7-(diethylamino)coumarin-3-carboxaldehyde were dissolved in anhydrous ethanol and refluxed overnight under an argon atmosphere. The solvent was dried and the mixture was purified by silica gel column chromatography to obtain an infrared fluorescent probe FS-C1, the structural formula of which is shown in IV:

3. The method for synthesizing a cyanine-like infrared fluorescent probe according to claim 2, wherein: In the step (1), the molar ratio of 1,8-naphtholactam, cesium carbonate and methyl iodide is 1:1.5:1.

2.

4. The method for synthesizing a cyanine-like infrared fluorescent probe according to claim 2, wherein: The separation and purification in step (1) is carried out by column chromatography, wherein the chromatography eluent is a mixed solvent of petroleum ether / ethyl acetate in a volume ratio of 23:1 for separation and purification.

5. The method for synthesizing a cyanine-like infrared fluorescent probe according to claim 2, wherein: The molar ratio of compound 1 to methylmagnesium chloride in step (2) is 1:4.

5.

6. The method for synthesizing a cyanine-like infrared fluorescent probe according to claim 2, wherein: In the step (3), the molar ratio of compound 2, -(diethylamino)coumarin-3-formaldehyde, and anhydrous sodium acetate is 1:1:0.

1.

7. The method for synthesizing a cyanine-like infrared fluorescent probe according to claim 2, wherein: The separation and purification in step (3) is performed by column chromatography, wherein the chromatography eluent is a dichloromethane / methanol mixed solution with a volume ratio of 10:

1.

8. A cyanine-like infrared fluorescent probe as claimed in claim 1 for use in the detection of organic amines in spoiled food.

9. Use of the cyanine-like infrared fluorescent probe for detecting organic amines in spoiled food according to claim 8, characterized in that: When organic amines are present in a neutral polar solution, the infrared fluorescent probe FS-C1 can respond quickly and react with the organic amines to produce an obvious color change.

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