2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe and preparation method and application thereof

Abstract

The invention discloses a 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe and a preparation method and application thereof. In the method, N-chitosan-4-hydrazine-1,8-naphthalimide is used as a raw material, and reacts with 1-naphthyl isothiocyanate to prepare 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide. Under 365nm ultraviolet light irradiation, the 2-(-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe solution does not emit fluorescence, and Hg is added thereto. 2+ After that, the fluorescent color of the solution changes from colorless to bright yellow, which is 2+ The detection limit reached 7.3×10 ‑8 M, response time 5min, as detection of Hg 2+ Fluorescent probes for ions have good application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescence detection, and relates to a 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe and a preparation method and application thereof. Background Art

[0002] Chitosan is an alkaline polysaccharide existing in nature. It is abundant in source and safe and non-toxic. Its unique molecular structure is easy to chemically modify and has good biocompatibility. Chitosan material raw materials are easily available and inexpensive. It is an environmentally friendly natural polymer material that is independent of petroleum resources. In recent years, it has been deeply studied in the fields of heavy metal adsorption, food additives, textiles, agriculture, etc. However, there are few reports on the work of chitosan and its derivatives in fluorescence sensing. Therefore, the development of new chitosan-based fluorescent functional materials is of great significance and has broad application prospects in biological imaging, sensor detection, etc.

[0003] Mercury is a heavy metal element widely used in modern industrial products. It plays a great role in cosmetics, medicines, measuring instruments and other fields. However, mercury ions (Hg 2+ ) is also a highly toxic heavy metal ion. Mercury ions can bind to sulfhydryl and disulfide groups in cell membranes or enzyme proteins, making them difficult to separate. They can affect many metabolic processes in cells, such as the synthesis of proteins and nucleic acids, thereby affecting cell function. 2+ It can enter the human body directly through the skin, digestive tract or respiratory tract, or it can enter the human body through enrichment in the food chain, thereby poisoning the central nervous system, kidneys, liver, oral cavity and skin. 2+ The main detection methods of Hg include electrochemical method, capillary electrophoresis method, atomic absorption spectrometry, etc. However, these methods also have problems such as expensive instruments, long analysis cycle and complex pretreatment, which are difficult to meet the requirements of convenience, speed and sensitivity of detection. The fluorescent probe method is simple to operate, highly sensitive and has a low detection limit. Therefore, a method for detecting Hg is designed and developed. 2+ The new fluorescent probe is of great significance. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide compound that can meet the detection of Hg 2+Another technical problem to be solved by the present invention is to provide a method for preparing a 2-(N-chitosan-1,8-naphthalene diimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe. Another technical problem to be solved by the present invention is to provide a method for preparing a 2-(N-chitosan-1,8-naphthalene diimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe as a detection probe for Hg 2+ Application of fluorescent probes.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe, the structural formula of which is:

[0007]

[0008] The preparation method of the 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe comprises the following steps: dispersing N-chitosan-4-hydrazino-1,8-naphthalimide in ethanol, adding 1-naphthyl isothiocyanate, and performing a nucleophilic addition reaction to obtain 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide.

[0009] The preparation method of the 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe comprises the following specific steps:

[0010] 1) Add 0.4-0.6 g of N-chitosan-4-hydrazino-1,8-naphthalene dicarboximide, 15-30 mL of ethanol and 0.04-0.06 g of 1-naphthyl isothiocyanate to a 50 mL single-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and react at room temperature for 16-32 hours;

[0011] 2) After the reaction is completed, the reaction solution is filtered through a sand core funnel, the filter cake is washed with distilled water and ethanol, and then vacuum dried at 45° C. for 8 to 14 hours to obtain the product 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide.

[0012] The prepared 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide solution (DMSO / water = 9 / 1, v / v) did not emit fluorescence under 365 nm ultraviolet light. 2+After that, the fluorescence color of the solution changed from colorless to bright yellow. Therefore, 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide can be used as a detection method for Hg 2+ of fluorescent probes.

[0013] The present invention uses N-chitosan-4-hydrazino-1,8-naphthalene dicarboximide as a raw material, and undergoes a nucleophilic addition reaction with 1-naphthyl isothiocyanate to obtain a 2-(N-chitosan-1,8-naphthalene dicarboximide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe. Experiments have confirmed that the solution of the prepared 2-(N-chitosan-1,8-naphthalene dicarboximide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe (DMSO / water=9 / 1, v / v) does not emit fluorescence under 365nm ultraviolet light irradiation, and Hg is added dropwise. 2+ After that, the fluorescence color of the solution changed from colorless to bright yellow. Therefore, 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide can be used as a detection 2+ Using fluorescent probes.

[0014] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0015] Chitosan is an alkaline polysaccharide existing in nature, with abundant sources, safe and non-toxic, and good biocompatibility. It is widely used in food additives, textiles, agriculture, environmental protection, beauty care, cosmetics and other fields. The present invention grafts 1-naphthyl isothiocyanate onto the molecular chain of N-chitosan-4-hydrazine-1,8-naphthalene dicarboximide, which not only has the excellent properties of the chitosan polymer itself, but also overcomes many limitations of small molecule fluorescent compounds. The 2-(N-chitosan-1,8-naphthalene dicarboximide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide fluorescent probe prepared in this way has the characteristics of good luminescence performance and stable structure. The 2-(N-chitosan-1,8-naphthalene dicarboximide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide solution (DMSO / water = 9 / 1, v / v) does not emit fluorescence under 365nm ultraviolet light, and the addition of Hg 2+ After that, the fluorescent color of the solution changes from colorless to bright yellow, which can be used for Hg 2+ The detection has great practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The infrared spectra of (a) N-chitosan-4-hydrazino-1,8-naphthalimide and (b) 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide are shown;

[0017] Figure 2 (a) is a high-resolution spectrum of the C1s peak of N-chitosan-4-hydrazino-1,8-naphthalimide, and (b) is a high-resolution spectrum of the C1s peak of 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide;

[0018] Figure 3 Under 365 nm ultraviolet light, 100 μM Hg was added to 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide solution (DMSO / water = 9 / 1, v / v). 2+ Before and after fluorescence photos;

[0019] Figure 4 It is a 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide solution (DMSO / water = 9 / 1, v / v) and Hg in the concentration range of 0 to 100 μM. 2+ Fluorescence spectrum of the effect;

[0020] Figure 5 It is a fluorescence spectrum of 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide solution (DMSO / water=9 / 1, v / v) added with different metal ions;

[0021] Figure 6 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide solution (DMSO / water = 9 / 1, v / v) was added with 100 μM Hg 2+ Response time diagram after. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0023] Example 1

[0024] The synthetic reaction formula of 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe is as follows:

[0025]

[0026] To a 50 mL single-necked flask equipped with a stirrer, a thermometer and a reflux condenser, add 0.5 g of N-chitosan-4-hydrazino-1,8-naphthalimide, 20 mL of ethanol and 0.05 g of 1-naphthyl isothiocyanate, and react at room temperature for 24 h. After the reaction, filter the reaction solution through a sand core funnel, wash the filter cake with distilled water and ethanol, and then vacuum dry it at 45 ° C for 12 h to obtain the product 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide.

[0027] The structure of 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide was analyzed by FT-IR. Figure 1 The infrared spectra of (a) N-chitosan-4-hydrazino-1,8-naphthalimide and (b) 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide are shown in Figure 1. Compared with N-chitosan-4-hydrazino-1,8-naphthalimide, 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide has a peak intensity of 1460 cm -1 A characteristic peak belonging to -NC=S appeared at , indicating the introduction of 1-naphthyl isothiocyanate, explaining the successful preparation of 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide.

[0028] XPS was used to analyze the structure of 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide. Figure 2 High-resolution spectra of the C1s peaks of (a) N-chitosan-4-hydrazino-1,8-naphthalimide and (b) 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide. For N-chitosan-4-hydrazino-1,8-naphthalimide, the three peaks at 287.80 eV, 286.0 eV and 284.90 eV are attributed to the peaks of OCO, COC / COH and CC / CN, respectively. Compared with N-chitosan-4-hydrazino-1,8-naphthalene dicarboximide, 2-(N-chitosan-1,8-naphthalene dicarboximide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide showed a peak at 287.0 eV attributed to the C=S bond, indicating the introduction of 1-naphthyl isothiocyanate, explaining the successful preparation of 2-(N-chitosan-1,8-naphthalene dicarboximide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide.

[0029] Example 2

[0030] The 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe prepared in Example 1 was dispersed in a solution (DMSO / water = 9 / 1, v / v) to a concentration of 8×10 -4 g / mL probe solution. Figure 3 As shown, 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide solution did not emit fluorescence under 365nm ultraviolet light. 2+ After 100 μM, the fluorescence color of the solution changed from colorless to bright yellow. Therefore, 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide can be used as a detection 2+ of fluorescent probes.

[0031] Example 3

[0032] The 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe prepared in Example 1 was dispersed in a solution (DMSO / water = 9 / 1, v / v) to a concentration of 8×10 -4 g / mL probe solution, and the fluorescence spectrophotometer (excitation wavelength: 365nm, slit width: 10.0nm / 5.0nm) was used to measure the 2+ (0~100μM) after fluorescence emission spectrum, such as Figure 4 The results show that as Hg 2+ As the concentration gradually increases, the fluorescence signal intensity of 2-(N-chitosan-1,8-naphthalene-4-imide-yl)-N-(naphthalene-1-yl)thiosemicarbazide at 543 nm gradually increases, indicating that 2-(N-chitosan-1,8-naphthalene-4-imide-yl)-N-(naphthalene-1-yl)thiosemicarbazide can sensitively detect Hg in the solution. 2+ Concentration, for Hg 2+ The detection limit is as low as 7.3×10 -8 mol / L.

[0033] Example 4

[0034] The 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe prepared in Example 1 was dispersed in a solution (DMSO / water = 9 / 1, v / v) to a concentration of 8×10 -4 g / mL probe solution, add 1.Hg 2+ 2.Mg 2+ 3.Fe 2+ 4.Sn 2+5.Ca 2+ 6. Zn 2+ 7.Co 2+ 8.Na + 9.Cd 2+ , 10.Cr 3+ , 11.Mn 2+ , 12.La + , 13.K + 、14.Al 3+ 15.Cu 2+ , 16.Ba 2+ The fluorescence emission spectrum was measured using a fluorescence spectrophotometer (excitation wavelength: 365 nm, slit width: 10.0 nm / 5.0 nm). Figure 5 It can be seen that the addition of Hg 2+ The fluorescence intensity of the probe solution increased dramatically after addition of other metal ions, such as Mg 2+ , Fe 2+ Sn 2+ , Ca 2+ 、Zn 2+ 、Co 2+ 、Na + 、Cd 2+ Cr 3+ , Mn 2+ ,La + , K + 、Al 3+ , Cu 2+ , Ba 2+ The fluorescence intensity of the probe solution was almost unchanged, indicating that the probe had no significant effect on Hg 2+ It has good selectivity and can be used for Hg 2+ Perform specificity testing.

[0035] Example 5

[0036] The 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe prepared in Example 1 was dispersed in a solution (DMSO / water = 9 / 1, v / v) to a concentration of 8×10 -4 g / mL probe solution, and the fluorescence spectrophotometer (excitation wavelength: 365nm, slit width: 10.0nm / 5.0nm) was used to measure the 2+ (100 μM) after fluorescence emission spectra. Figure 6 It can be seen that the addition of Hg 2+ After that, the fluorescence intensity of the probe solution gradually increased, reached equilibrium in 5 minutes, and remained stable in the following 20 minutes. 2+ With fast response, it can2 + Perform real-time detection.

Claims

1. 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe, characterized in that: The structural formula is:

2. The method for preparing the 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe according to claim 1, characterized in that: N-chitosan-4-hydrazino-1,8-naphthalimide was dispersed in ethanol, and 1-naphthyl isothiocyanate was added to carry out nucleophilic addition reaction to prepare 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide.

3. The method for preparing the 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe according to claim 2, characterized in that: The specific steps are as follows: 1) Add 0.4-0.6 g of N-chitosan-4-hydrazino-1,8-naphthalene dicarboximide, 15-30 mL of ethanol and 0.04-0.06 g of 1-naphthalene isothiocyanate to a 50 mL single-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and react at room temperature for 16-32 hours; 2) After the reaction is completed, the reaction solution is filtered through a sand core funnel, the filter cake is washed with distilled water and ethanol, and then vacuum dried at 45° C. for 8 to 14 hours to obtain the product 2-(N-chitosan-1,8-naphthalene diimide-4-yl)-N-(naphthalene-1-yl) thiosemicarbazide.

4. The 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe according to claim 1 is used to detect Hg 2+ Application in.

5. The use according to claim 4, characterized in that: Under 365nm ultraviolet light irradiation, the 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe solution did not emit fluorescence. 2+ After that, the fluorescent color of the solution changed from colorless to bright yellow.

6. The use according to claim 5, characterized in that: The solvent of the 2-(N-chitosan-1,8-naphthalimide-4-yl)-N-(naphthalene-1-yl)thiosemicarbazide fluorescent probe solution is DMSO / water with a volume ratio of 9 / 1.

Images