Naphthalimide fluorescent dye as well as preparation method and application thereof
By synthesizing naphthalimide fluorescent dyes as fluorescent probes, the problems of high sensitivity and simplicity in palladium residue detection have been solved, achieving efficient detection of palladium ions and meeting the accuracy requirements of drug quality control.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI HERYI CHEM
- Filing Date
- 2025-12-29
- Publication Date
- 2026-05-12
AI Technical Summary
In the existing technology, the detection methods for palladium residues caused by palladium catalysts in the production of active pharmaceutical ingredients are expensive and complex, which is difficult to meet the needs of small and medium-sized enterprises. In addition, the sensitivity of traditional detection methods is insufficient and cannot effectively control the trace residues of palladium ions.
A naphthalimide-based fluorescent dye was developed as a fluorescent probe. A palladium ion recognition group was introduced through a chemical reaction, and the high-sensitivity detection of palladium ions was achieved by utilizing changes in fluorescence signal. The specific steps included the reaction of 4-bromo-1,8-naphthalenedicarboxylic anhydride with n-butylamine, carbonylation, redox reaction, and substitution reaction to synthesize the naphthalimide-based fluorescent dye.
It achieves highly sensitive detection of palladium ions, with good specificity and low detection limit, which can meet the accuracy requirements of drug quality control and simplify the detection process.
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Figure CN122010838A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of fluorescent dye technology, specifically to a naphthalimide-based fluorescent dye, its preparation method, and its application. Background Technology
[0002] Palladium, a precious metal, is widely used in industrial catalysts and electronic components, but its potential health hazards cannot be ignored. Palladium and its compounds mainly enter the human body through inhalation or skin contact. Short-term exposure may cause respiratory irritation, such as coughing and sore throat, and in severe cases, chemical pneumonia; long-term exposure may cause pulmonary fibrosis, affecting respiratory function. The cumulative effect of palladium is also reflected in skin allergic reactions; some people develop contact dermatitis after wearing palladium-containing jewelry, manifesting as redness, swelling, itching, and even ulceration. At the immune system level, palladium may interfere with white blood cell activity, weaken the body's resistance, and increase the risk of infection.
[0003] The widespread use of palladium catalysts (such as palladium on carbon and palladium acetate) in the production of active pharmaceutical ingredients (APIs) can lead to trace amounts of palladium residues in the product. These residues may trigger allergic reactions, organ toxicity, or long-term health risks. Therefore, pharmacopoeias in various countries have set strict limits on palladium residues in APIs. For example, the Chinese Pharmacopoeia stipulates that palladium residues must not exceed 10 parts per million (ppm) to ensure drug safety. Common detection methods mainly include atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). AAS quantifies palladium by measuring the absorption of light at specific wavelengths, and is simple to operate, but has relatively low sensitivity. ICP-MS, utilizing plasma ionization technology, has higher sensitivity and multi-element detection capabilities, and can accurately identify trace palladium residues. The detection process typically includes sample dissolution, filtration, and instrumental analysis, such as dissolving the API in nitric acid before injection to reduce matrix interference. The selection of these methods requires a trade-off between cost, accuracy, and practical needs to meet drug quality control standards. ICP-MS, in particular, is extremely expensive and requires professional maintenance, which is difficult for some small and medium-sized API intermediates to purchase and maintain. Therefore, developing simpler palladium ion detection methods is of greater significance for the quality control of active pharmaceutical ingredients.
[0004] Fluorescent probe technology, with its unique fluorescence signal amplification mechanism, exhibits significant advantages in detection sensitivity. Its core lies in the specific binding of probe molecules to the target analyte, triggering controllable changes in fluorescence intensity, wavelength, or lifetime. This signal conversion mechanism allows even subtle changes in target analyte concentration to be precisely captured by optical systems. For example, in the field of single-molecule detection, fluorescent probes can overcome the physical limitations of traditional methods, achieving detection sensitivities at the picomolar or even femtomolar levels, making early screening for disease biomarkers possible.
[0005] In summary, this invention addresses the problems existing in the prior art by developing a fluorescent dye and its preparation method, and applies it to the detection of palladium ions in active pharmaceutical ingredients and chemical intermediates. Summary of the Invention
[0006] To overcome the shortcomings of the prior art, the present invention provides a naphthalimide fluorescent dye for palladium ion detection and a method for its preparation.
[0007] The technical problem to be solved by the present invention is achieved by the following technical solution: The first objective of this invention is to provide a naphthalimide-based fluorescent dye with the following structural formula:
[0008] A second objective of this invention is to provide a method for preparing the aforementioned naphthalimide fluorescent dye, comprising the following steps: S1, 4-bromo-1,8-naphthoic anhydride reacts with n-butylamine to give intermediate 1; S2 and intermediate 1 undergo a carbonylation reaction with N,N-dimethylformamide to obtain intermediate 2; S3 and intermediate 2 undergo a redox reaction with hydroxylamine hydrochloride to obtain intermediate 3; S4 and intermediate 3 undergo a substitution reaction with 3-bromopropyne to obtain the naphthalimide fluorescent dye.
[0009] The synthesis route is as follows:
[0010] Furthermore, the molar ratio of 4-bromo-1,8-naphthoic anhydride to n-butylamine is 1:(1~2).
[0011] The carbonylation reaction described in this invention uses N,N-dimethylformamide (DMF) as both the reaction solvent and the reaction substrate, so the amount of DMF can be far in excess.
[0012] Furthermore, the carbonylation reaction is carried out in the presence of a metal catalyst. Even further, the metal catalyst includes, but is not limited to, at least one of manganese dioxide and elemental samarium.
[0013] Furthermore, the molar ratio of intermediate 2 to hydroxylamine hydrochloride is 1:(1~4).
[0014] Furthermore, the redox reaction is carried out under alkaline conditions, which are provided by at least one of the alkaline substances such as sodium acetate, potassium carbonate, sodium carbonate, and sodium bicarbonate.
[0015] Furthermore, the molar ratio of intermediate 3 to 3-bromopropyne is 1:(1~2).
[0016] Furthermore, the substitution reaction is carried out in the presence of an acid-binding agent. Even further, the acid-binding agent includes, but is not limited to, at least one of sodium hydride and potassium hydride. The acid-binding agent promotes the formation of the naphthalimide fluorescent dye by neutralizing the hydrogen bromide byproduct generated during the substitution reaction.
[0017] A third objective of this invention is to provide the application of the aforementioned naphthalimide fluorescent dyes in palladium ion detection. Specifically, this invention uses the aforementioned naphthalimide fluorescent dyes as fluorescent probes to detect palladium ion content in pharmaceutical raw materials and chemical intermediates.
[0018] The principle of palladium ion detection using the naphthalimide fluorescent dyes described in this invention is as follows:
[0019] The above detection principle is based on Figure 1 and Figure 2 This has been confirmed.
[0020] The beneficial effects of this invention are as follows: This invention uses naphthalimide compounds as two-photon fluorescent substrates and introduces palladium ion recognition groups through chemical reactions, causing the fluorescence of the compounds to be quenched, thus obtaining naphthalimide fluorescent dyes; the naphthalimide fluorescent dyes undergo a specific reaction after recognizing palladium ions, resulting in enhanced fluorescence and generating fluorescence emission at a wavelength of 460 nm in the excited state at a wavelength of 360 nm; by utilizing this "on" characteristic, this invention provides a powerful detection tool for controlling the content of palladium ions in active pharmaceutical ingredients and chemical intermediates. Attached Figure Description
[0021] Figure 1 This is the mass spectrum of the naphthalimide fluorescent dye described in this invention; Figure 2 This is the mass spectrum of the naphthalimide fluorescent dye described in this invention after reacting with palladium ions; Figure 3 This is the UV-Vis absorption spectrum of the naphthalimide fluorescent probe described in this invention; Figure 4 This is the UV-Vis absorption spectrum of the naphthalimide fluorescent probe described in this invention after reacting with palladium ions; Figure 5 The emission spectrum of the naphthalimide fluorescent probe described in this invention after reacting with palladium ions is shown. Figure 6 The fluorescence detection selectivity of the naphthalimide fluorescent dye described in this invention includes: 1-palladium acetate, 2-copper acetate, 3-ferric acetate, 4-zinc acetate, 5-calcium chloride, 6-sodium chloride, 7-potassium chloride, 8-sodium bromide, 9-sodium iodide, and 10-hydrogen peroxide. Figure 7 This is a graph showing the linear relationship between the fluorescence emission intensity and palladium ion concentration of the naphthalimide fluorescent dye used in this invention for detecting palladium ion residues in a pharmaceutical raw material. Detailed Implementation
[0022] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments and illustrations.
[0023] Example 1 Synthesis of intermediate 1: 4-Bromo-1,8-naphthalenedicarboxylic anhydride (10 g, 36 mmol) and n-butylamine (3.9 g, 54 mmol) were added to 200 mL of ethanol, and the mixture was refluxed and stirred for 4 h. After the reaction was completed, the precipitate was collected by centrifugation, dried, and intermediate 1 was obtained in 100% yield.
[0024] Synthesis of intermediate 2: Under nitrogen protection, samarium powder (3 g, 20 mmol) and manganese dichloride (0.25 g, 2 mmol) were added to 50 mL of DMF. Then, intermediate 1 (6.64 g, 20 mmol) was added at 50 °C, and the mixture was stirred for 4 h. After the reaction was complete, 100 mL of dilute hydrochloric acid (1 M) was added, and the mixture was extracted with ethyl acetate (200 mL × 3). The organic layer was washed with brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (using petroleum ether and ethyl acetate in a volume ratio of 40:1 as eluent) to obtain intermediate 2 with a yield of 94% and a purity of 98.2%.
[0025] Synthesis of intermediate 3: Intermediate 2 (3.37 g, 12 mmol) was dissolved in 250 mL of dichloromethane, and then hydroxylamine hydrochloride (1.6 g, 24 mmol) and sodium acetate (2.4 g, 30 mmol) dissolved in 75 mL of ethanol were added. The mixture was stirred at room temperature for 3 h. After the reaction was completed, the solution was concentrated under reduced pressure and purified by silica gel column chromatography (using dichloromethane as eluent) to give intermediate 3 in 85% yield and 98.5% purity.
[0026] Synthesis of fluorescent probes: Intermediate 3 (2.96 g, 10 mmol) and sodium hydride (0.24 g, 10 mmol) were added to 20 mL of tetrahydrofuran and stirred at 0 °C for 30 min. Then, a mixed solution of 3-bromopropyne (1.77 g, 15 mmol) and 20 mL of tetrahydrofuran was added, and the mixture was stirred at room temperature for 1 h. After the reaction was completed, 100 mL of water was added to terminate the reaction. The mixture was filtered, and the residue was purified by silica gel column chromatography (using methanol-dichloromethane at a volume ratio of 1:20 as the eluent) to obtain the fluorescent probe with a yield of 80% and a purity of 98.3%.
[0027] Example 2 Synthesis of intermediate 1: 4-Bromo-1,8-naphthalenedicarboxylic anhydride (10 g, 36 mmol) and n-butylamine (2.6 g, 36 mmol) were added to 200 mL of N,N-dimethylformamide, and the mixture was refluxed and stirred for 4 h. After the reaction was completed, the precipitate was collected by centrifugation, dried, and intermediate 1 was obtained in 95% yield.
[0028] Synthesis of intermediate 2: Under nitrogen protection, samarium powder (3 g, 20 mmol) and manganese dichloride (0.25 g, 2 mmol) were added to 50 mL of DMF. Then, intermediate 1 (6.64 g, 20 mmol) was added at 50 °C, and the mixture was stirred for 4 h. After the reaction was complete, 100 mL of dilute hydrochloric acid (1 M) was added, and the mixture was extracted with ethyl acetate (200 mL × 3). The organic layer was washed with brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (using petroleum ether-ethyl acetate at a volume ratio of 40:1 as the eluent) to obtain intermediate 2 with a yield of 94% and a purity of 98.3%.
[0029] Synthesis of intermediate 3: Intermediate 2 (3.37 g, 12 mmol) was dissolved in 250 mL of dichloromethane, and then hydroxylamine hydrochloride (3.3 g, 48 mmol) and potassium carbonate (4.05 g, 30 mmol) dissolved in 75 mL of ethanol were added. The mixture was stirred at room temperature for 3 h. After the reaction was completed, the solution was concentrated under reduced pressure and purified by silica gel column chromatography (using dichloromethane as eluent) to give intermediate 3 in 89% yield and 99.5% purity.
[0030] Synthesis of fluorescent probes: Intermediate 3 (2.96 g, 10 mmol) and sodium hydride (0.24 g, 10 mmol) were added to 20 mL of tetrahydrofuran and stirred at 0 °C for 30 min. Then, a mixed solution of 3-bromopropyne (1.19 g, 10 mmol) and 20 mL of tetrahydrofuran was added, and the mixture was stirred at room temperature for 1 h. After the reaction was completed, 100 mL of water was added to terminate the reaction. The mixture was filtered, and the residue was purified by silica gel column chromatography (using methanol-dichloromethane at a volume ratio of 1:20 as the eluent) to obtain the fluorescent probe with a yield of 76% and a purity of 98.4%.
[0031] Example 3 Synthesis of intermediate 1: 4-Bromo-1,8-naphthalenedicarboxylic anhydride (10 g, 36 mmol) and n-butylamine (5.3 g, 72 mmol) were added to 200 mL of N,N-dimethylformamide, and the mixture was refluxed and stirred for 4 h. After the reaction was completed, the precipitate was collected by centrifugation, dried, and intermediate 1 was obtained in 100% yield.
[0032] Synthesis of intermediate 2: Under nitrogen protection, samarium powder (3 g, 20 mmol) and manganese dichloride (0.5 g, 4 mmol) were added to 50 mL of DMF. Then, intermediate 1 (6.64 g, 20 mmol) was added at 50 °C, and the mixture was stirred for 4 h. After the reaction was complete, 100 mL of dilute hydrochloric acid (1 M) was added, and the mixture was extracted with ethyl acetate (200 mL × 3). The organic layer was washed with brine, dried over anhydrous sodium sulfate, concentrated under reduced pressure, and purified by silica gel column chromatography (using petroleum ether and ethyl acetate in a volume ratio of 40:1 as eluent) to obtain intermediate 2 with a yield of 95% and a purity of 98.7%.
[0033] Synthesis of intermediate 3: Intermediate 2 (3.37 g, 12 mmol) was dissolved in 250 mL of dichloromethane, and then hydroxylamine hydrochloride (0.8 g, 12 mmol) and sodium carbonate (3.05 g, 30 mmol) dissolved in 75 mL of ethanol were added. The mixture was stirred at room temperature for 3 h. After the reaction was completed, the mixture was concentrated under reduced pressure and purified by silica gel column chromatography (using dichloromethane as eluent) to give intermediate 3 in 75% yield and 98.9% purity.
[0034] Synthesis of fluorescent probes: Intermediate 3 (2.96 g, 10 mmol) and sodium hydride (0.24 g, 10 mmol) were added to 20 mL of tetrahydrofuran and stirred at 0 °C for 30 min. Then, a mixed solution of 3-bromopropyne (2.38 g, 20 mmol) and 20 mL of tetrahydrofuran was added, and the mixture was stirred at room temperature for 1 h. After the reaction was completed, 100 mL of water was added to terminate the reaction. The mixture was filtered, and the residue was purified by silica gel column chromatography (using methanol-dichloromethane at a volume ratio of 1:20 as the eluent) to obtain the fluorescent probe with a yield of 84% and a purity of 98.2%.
[0035] Example 4 The fluorescent probe synthesized in Example 1 was prepared into a 10 mM stock solution using dimethyl sulfoxide (DMSO). 1 μL of the stock solution was added to 999 μL of ultrapure water, and the solution was shaken on a shaker at 37°C for 10 min. The UV-Vis absorption spectrum of the solution was measured, and the results are as follows: Figure 3 As shown.
[0036] from Figure 3 It can be seen that the maximum ultraviolet absorption wavelength of the fluorescent probe itself is at 340 nm, with no obvious emission wavelength.
[0037] Example 5 The fluorescent probe synthesized in Example 1 was prepared into a 10 mM stock solution using DMSO. 1 μL of the stock solution was added to 998 μL of ultrapure water, along with 1 μL of 10 mM palladium acetate aqueous solution. The solution was shaken on a shaker at 37°C for 10 min. The UV-Vis absorption and fluorescence emission spectra of the solution were measured. Results... Figure 3 and Figure 4 As shown.
[0038] from Figure 4 It can be seen that after the fluorescent probe reacts with palladium ions, its maximum ultraviolet absorption wavelength changes from 340 nm to 360 nm.
[0039] from Figure 5 It can be seen that after the fluorescent probe reacts with palladium ions, it exhibits significant fluorescence emission at a wavelength of 460 nm.
[0040] Example 6 The fluorescent probe synthesized in Example 1 was prepared into a 10 mM stock solution using DMSO. Ten 1 μL portions of the stock solution were added to 998 μL of ultrapure water, followed by 1 μL of 10 mM aqueous solutions of palladium acetate, copper acetate, ferric acetate, zinc acetate, calcium chloride, sodium chloride, potassium chloride, sodium bromide, sodium iodide, or hydrogen peroxide. The solutions were shaken on a shaker at 37°C for 10 min. The fluorescence intensity of the solutions was measured at an excitation wavelength of 360 nm and an emission wavelength of 460 nm. The results are as follows: Figure 6 As shown.
[0041] from Figure 6 It can be seen that the fluorescent probe only produces a fluorescent signal for palladium acetate, which indicates that it has good specificity.
[0042] Example 7 The fluorescent probe synthesized in Example 1 was prepared into a 10 mM stock solution using DMSO. 1 μL of the stock solution was added to 898 μL of ultrapure water, along with 100 μL of 10 mM azithromycin DMSO solution. Then, 1 μL of different concentrations of palladium acetate aqueous solutions (2 mM, 4 mM, 6 mM, 8 mM, 10 mM, 12 mM) were added. The solution was shaken on a shaker at 37°C for 10 min. The fluorescence intensity of the solution was measured at an excitation wavelength of 360 nm and an emission wavelength of 460 nm, and a concentration-fluorescence intensity curve was fitted. The results are as follows: Figure 7 As shown.
[0043] from Figure 7 It can be seen that the detection limit of this fluorescent probe for palladium ions in azithromycin API is 10 μM.
[0044] In summary, when the fluorescent dye described in this invention is used as a probe for palladium ion detection, it has advantages such as high specificity and low detection limit, which can ensure detection accuracy and sensitivity.
[0045] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.
Claims
1. A naphthalimide-based fluorescent dye, the structural formula of which is as follows: 。 2. The method for preparing the naphthalimide fluorescent dye according to claim 1, characterized in that, Includes the following steps: S1, 4-bromo-1,8-naphthoic anhydride reacts with n-butylamine to give intermediate 1; S2 and intermediate 1 undergo a carbonylation reaction with N,N-dimethylformamide to obtain intermediate 2; S3 and intermediate 2 undergo a redox reaction with hydroxylamine hydrochloride to obtain intermediate 3; S4, intermediate 3 undergoes a substitution reaction with 3-bromopropyne to obtain the naphthalimide fluorescent dye; The synthesis route is as follows: 。 3. The method for preparing naphthalimide fluorescent dyes according to claim 2, characterized in that: The molar ratio of 4-bromo-1,8-naphthalenedicarboxylic anhydride to n-butylamine is 1:(1~2).
4. The method for preparing naphthalimide fluorescent dyes according to claim 2, characterized in that: The carbonylation reaction is carried out in the presence of a metal catalyst.
5. The method for preparing naphthalimide fluorescent dyes according to claim 4, characterized in that: The metal catalyst is manganese dioxide and elemental samarium.
6. The method for preparing naphthalimide fluorescent dyes according to claim 2, characterized in that: The molar ratio of intermediate 2 to hydroxylamine hydrochloride is 1:(1~4).
7. The method for preparing naphthalimide fluorescent dyes according to claim 2, characterized in that: The redox reaction is carried out under alkaline conditions, which are provided by at least one of sodium acetate, potassium carbonate, sodium carbonate, and sodium bicarbonate.
8. The method for preparing naphthalimide fluorescent dyes according to claim 2, characterized in that: The molar ratio of intermediate 3 to 3-bromopropyne is 1:(1~2).
9. The method for preparing naphthalimide fluorescent dyes according to claim 2, characterized in that: The substitution reaction is carried out in the presence of an acid-binding agent; preferably, the acid-binding agent is at least one of sodium hydride and potassium hydride.
10. The application of the naphthalimide fluorescent dye according to claim 1 in palladium ion detection.