A 1,8-naphthalimide-rhodamine fluorescent probe, its preparation method and application in detecting Fe 3+ ions

Abstract

The present invention discloses a 1,8-naphthalimide-rhodamine fluorescent probe and its preparation method and application, belonging to the technical field of synthesis methods of novel composite materials of fluorescent probes. This method uses rhodamine B as the matrix, through an amide condensation reaction, with anhydrous ethylenediamine as the bridging molecule, and finally prepares a 1,8-naphthalimide-rhodamine fluorescent probe. The prepared 1,8-naphthalimide-rhodamine fluorescent probe uses rhodamine B as the fluorescent group and 1,8-naphthalic anhydride as the recognition group, and has high sensitivity and strong selectivity for Fe 3+ It has linear quenching in the range of 0 to 330 μmol / L, the detection limit ranges from 0.84 to 0.95 μmol / L, and has strong anti-interference ability against other metal ions. Compared with single-metal-ion fluorescent probes, the 1,8-naphthalimide-rhodamine fluorescent probe prepared by the present invention has good application prospects in the detection of metal ions and their in-situ online quantitative analysis, and has good selectivity for Fe 3+ and can be used for the trace detection of various metal ions in the environment, biomedicine and food.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthesis methods of novel composite materials of fluorescent probes, and particularly relates to a 1,8-naphthalimide-rhodamine fluorescent probe, a preparation method thereof, and an application thereof in detecting Fe 3+ ions in it. Background Art

[0002] There are numerous heavy metals in nature, such as iron, mercury, lead, cadmium, etc. When they accumulate in the human body to a certain extent, they will cause chronic poisoning and environmental pollution. As a typical heavy metal, iron is widely present in nature, accounting for about 4.75% of the total crustal content, second only to oxygen, silicon, and aluminum. Pure iron is a flexible and ductile silver-white metal, used to make the iron cores of generators and motors. Iron and its compounds are also used to make magnets, drugs, inks, pigments, abrasives, etc., and are one of the so-called "ferrous metals" in industry. Iron is an essential trace element in the human body and an important component of hemoglobin. The total amount of iron in the human body is about 4 - 5 grams. It exists in red blood cells that supply oxygen to muscles and is also a component of many enzymes and immune system compounds. The functions of iron also include promoting development, enhancing immunity, regulating tissue respiration, preventing fatigue, etc. Most of the iron required by the human body comes from food, but the intake must be controlled. Iron itself is not toxic, but when an excessive amount is ingested or an overdose of iron is taken by mistake, methemoglobinemia will occur, endangering human health and even life.

[0003] Therefore, it is very necessary to design a simple, sensitive, and efficient method for detecting Fe 3+ ions. Commonly recognized heavy metal detection methods include ultraviolet spectrophotometry (UV), atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), inductively coupled plasma method (ICP), inductively coupled plasma mass spectrometry (ICP-MS), etc. However, their detection costs are relatively high and they do not have universality. Molecular fluorescent probes have received extensive attention due to their advantages such as convenience, high sensitivity, and high selectivity. Kang Yulong et al. prepared a novel colorimetric fluorescent probe using rhodamine 6G, and the detection limit for Fe 3+ ions was 3.87 μmol / L (Kang Yulong, Bai Tonglu, Han Bo, et al. A rhodamine 6G-based "Off-On" type colorimetric fluorescent probe for Fe 3+ ions [J]. Chemistry Bulletin, 2023, 86(1): 8.). Rhodamine B is an artificially synthesized dye with bright peach red color, soluble in water and ethanol, slightly soluble in acetone, chloroform, hydrochloric acid, and sodium hydroxide solution. The aqueous solution is blue-red, with strong fluorescence after dilution, and the alcoholic solution has red fluorescence. It is commonly used as a fluorescent stain in laboratories, etc. It has the advantages of high photostability, low sensitivity to acids and bases, both the maximum absorption wavelength and the maximum fluorescence wavelength being in the visible light region, and little interference from the external background.

[0004] Since the existing Fe 3+ fluorescent probes still have problems such as low sensitivity, poor selectivity, and harsh testing conditions, there is still an urgent need to design and synthesize a rhodamine B-based fluorescent probe with stable structure, high selectivity, high sensitivity, high efficiency, and accuracy for detecting Fe 3+ . Summary of the Invention

[0005] In order to overcome the disadvantages of the above-mentioned prior art, the object of the present invention is to provide a 1,8-naphthalimide-rhodamine fluorescent probe, its preparation method, and its application in detecting Fe 3+ to solve the problems of low sensitivity, poor selectivity, and harsh testing conditions existing in the existing Fe 3+ fluorescent probes.

[0006] To achieve the above object, the present invention adopts the following technical solutions:[[]]

[0007] The present invention discloses a 1,8-naphthalimide-rhodamine fluorescent probe, and the structural formula of the 1,8-naphthalimide-rhodamine fluorescent probe is:[[]]

[0008]

[0009] The present invention also discloses a preparation method of the above 1,8-naphthalimide-rhodamine fluorescent probe, which includes the following steps:[[]]

[0010] 1) Dissolve rhodamine B in ethanol, then add anhydrous ethylenediamine, after heating under reflux and rotary evaporation, add dichloromethane, after extraction, collect the organic phase and add anhydrous sodium sulfate, and after rotary evaporation, obtain a rhodamine B ethylenediamine intermediate;[[]]

[0011] 2) Dissolve the rhodamine B ethylenediamine intermediate prepared in step 1) in ethanol, then add a 1,8-naphthalic anhydride solution, after the reaction is completed, let it stand, and after the product recrystallizes and precipitates, filter it by suction and wash it to obtain a 1,8-naphthalimide-rhodamine fluorescent probe.[[]]

[0012] Preferably, in step 1), the mass ratio of rhodamine B:ethanol:anhydrous ethylenediamine:dichloromethane:anhydrous sodium sulfate is (1.0 - 1.5):(20 - 30):(2 - 3):(30 - 40):(20 - 25).[[]]

[0013] Preferably, in step 1), the conditions for the heating under reflux reaction are: reacting at 70 - 85°C for 6 - 8 h.[[]]

[0014] Preferably, in step 1), the number of extraction times is 8 - 9 times.[[]]

[0015] Preferably, in step 2), the 1,8-naphthalic anhydride solution is prepared by dissolving 1,8-naphthalic anhydride in ethanol, and the mass ratio of 1,8-naphthalic anhydride to ethanol is (0.12 - 0.24):(5 - 10).

[0016] Preferably, in step 2), the mass ratio of rhodamine B ethylenediamine intermediate to 1,8-naphthalic anhydride is (0.3 - 0.6):(0.12 - 0.24).

[0017] Preferably, in step 2), the reaction conditions are: reacting at 55 - 65 °C for 5 - 7 h.

[0018] Preferably, in step 2), the standing time is 8 - 12 h.

[0019] The present invention also discloses the application of the above 1,8-naphthalimide-rhodamine fluorescent probe in the trace detection and content analysis of metal ions. The 1,8-naphthalimide-rhodamine fluorescent probe has a linear quenching in the range of 0 - 330 μmol / L for Fe 3+ and the detection limit range is 0.84 - 0.95 μmol / L.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention discloses a 1,8-naphthalimide-rhodamine fluorescent probe, which modifies the rhodamine B molecule through organic synthesis, making it have high anti-interference ability and sensitivity. It can detect target ions at extremely low ion concentrations, and can achieve efficient, accurate and rapid detection of Fe 3+ with high selectivity for metal ions. The detectable Fe 3+ concentration range is 0 - 330 mmol / L. When detecting, adding Fe 3+ , the solution changes from colorless to purplish red, which is not only convenient for observation but also has good stability. In addition, the fluorescent probe has a fast reaction rate with Fe 3+ , its fluorescence intensity can tend to be stable within 3 min, high sensitivity, relatively long absorption and emission wavelengths, small background interference, and almost no response to other metal ions, with strong anti-interference ability to other metal ions, and can be widely used for the detection and in-situ online quantitative analysis of Fe 3+ .

[0022] The present invention also discloses a preparation method of the above-mentioned 1,8-naphthalimide-rhodamine fluorescent probe. Through an amide condensation reaction, using anhydrous ethylenediamine as a bridging molecule, rhodamine B as a fluorescent group, and 1,8-naphthalic acid imide as a recognition group, the 1,8-naphthalimide-rhodamine fluorescent probe is synthesized. Compared with traditional fluorescent probes, it has high selectivity. The raw materials used follow the concept of environmental protection and no environmental pollutants are generated during the preparation process, and it has broad application prospects. Compared with traditional fluorescent probes, the synthesis process of the method of the present invention is simple, the raw materials are inexpensive and easily available, the detection response time is short, and the applicability is strong.

[0023] The present invention also discloses the application of the above-mentioned 1,8-naphthalimide-rhodamine fluorescent probe in the trace detection and content analysis of metal ions. This fluorescent probe linearly quenches in the range of 0-330 μmol / L for Fe 3+ and the detection limit ranges from 0.84 to 0.95 μmol / L. Compared with single-metal-ion fluorescent probes, the 1,8-naphthalimide-rhodamine fluorescent probe prepared by the present invention has good selectivity for Fe 3+ and can be used for the trace detection of various metal ions in the environment, biomedicine and food. Description of the Drawings

[0024] Figure 1 is a schematic diagram of the synthesis of the 1,8-naphthalimide-rhodamine fluorescent probe disclosed by the present invention;

[0025] Figure 2 is the nuclear magnetic resonance spectrum of the 1,8-naphthalimide-rhodamine fluorescent probe prepared in Example 1 of the present invention; among them, (a) is the hydrogen spectrum and (b) is the carbon spectrum;

[0026] Figure 3 is the fluorescence response diagram of the 1,8-naphthalimide-rhodamine fluorescent probe prepared in Example 1 of the present invention to different metal ions. Detailed Embodiments

[0027] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0029] The present invention will be further described in detail below with reference to the accompanying drawings:

[0030] The present invention provides a preparation method of a 1,8-naphthalimide-rhodamine fluorescent probe. Through an amide condensation reaction, with ethylenediamine as the bridging molecule, rhodamine B as the fluorescent group, and naphthoic anhydride as the recognition group, a novel Fe 3+ fluorescent probe 1,8-naphthalimide-rhodamine fluorescent probe was synthesized. This probe has high selectivity and sensitivity for Fe 3+ and has strong anti-interference ability against other metal ions, and can be used as the basis for qualitative and quantitative detection of Fe 3+ .

[0031] The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe disclosed by the present invention specifically includes the following steps:

[0032] 1) By mass, dissolve 1.0 - 1.5 parts of rhodamine B in 20 - 30 parts of ethanol, and then gradually add 2 - 3 parts of anhydrous ethylenediamine dropwise to the above solution, and carry out a heating reflux reaction; after the reaction is completed, rotary evaporate to remove the solvent to obtain a pink substance, then add 30 - 40 parts of dichloromethane to it, dissolve it, extract it with distilled water 8 - 9 times, collect the organic phase and add 20 - 25 parts of anhydrous sodium sulfate to remove water, and then rotary evaporate to remove the solvent again to obtain a red rhodamine B ethylenediamine intermediate;

[0033] 2) Weigh 0.3 - 0.6 parts of the rhodamine B ethylenediamine intermediate prepared in step 1) and dissolve it in 20 - 30 parts of ethanol, weigh 0.12 - 0.24 parts of 1,8-naphthoic anhydride and dissolve it in 5 - 10 parts of ethanol, and drop it into the above solution under stirring conditions, and react at 55 - 65 °C for 5 - 7 h; after the reaction is completed, let the solution stand for 8 - 12 h to crystallize the product therein, and then carry out suction filtration, and wash the solid obtained by suction filtration three times with anhydrous ethanol to obtain a yellow solid product 1,8-naphthalimide-rhodamine fluorescent probe.

[0034] In step 1), the mass ratio of rhodamine B to anhydrous ethylenediamine is (1 - 1.5):(2 - 3).

[0035] In step 1), the conditions for the heating reflux reaction are: reacting at 70 - 85 °C for 6 - 8 h.

[0036] In step 2), the mass ratio of the rhodamine B ethylenediamine intermediate to 1,8 - naphthalic anhydride is (0.3 - 0.6):(0.12 - 0.24).

[0037] In step 2), the reaction temperature of the rhodamine B ethylenediamine intermediate and 1,8 - naphthalic anhydride in a solvent containing ethanol is 55 - 65 °C, and the reaction time is 5 - 7 h.

[0038] The fluorescent probe prepared by the above - mentioned preparation method reacts with Fe 3+ with a fast reaction rate. Its fluorescence intensity can reach stability within 3 min, has high sensitivity, relatively long absorption and emission wavelengths, low background interference, and almost no response to other metal ions, with strong anti - interference ability to other metal ions. It can be widely used for the detection and in - situ online quantitative analysis of Fe 3+ The 1,8 - naphthalimide - rhodamine fluorescent probe has significant application performance and characteristics in the adsorption ability to Fe 3+ Detect the detection ability of this fluorescent probe for metal ions. For Fe 3+ it shows a linear quenching in the range of 0 - 330 μmol / L, and the detection limit range is 0.84 - 0.95 μmol / L.

[0039] Example 1

[0040] A preparation method of a 1,8 - naphthalimide - rhodamine fluorescent probe, comprising the following steps:

[0041] 1) By mass, first take 1.0 part of rhodamine B and dissolve it in 20 parts of ethanol, then take 2 parts of anhydrous ethylenediamine and add it dropwise to the above - mentioned solution, and react under heating reflux at 70 °C for 8 h; after the reaction is completed, remove the solvent by rotary evaporation at 60 °C to obtain a pink substance. Then add 30 parts of dichloromethane to it, dissolve it, extract it repeatedly 8 times with 20 mL of distilled water, collect the organic phase and add 20 parts of anhydrous sodium sulfate to absorb water, and then rotary evaporate to remove the solvent again to obtain a red rhodamine B ethylenediamine intermediate;

[0042] 2) By mass fraction, take 0.3 parts of the rhodamine B ethylenediamine intermediate prepared in step 1) and dissolve it in 20 parts of ethanol. Take 0.12 parts of 1,8-naphthalic anhydride and dissolve it in 5 parts of ethanol. Under stirring conditions, drop it into the above solution and react at 55 °C for 5 h; after the reaction is completed, let the solution stand for 8 h to crystallize the product therein, then carry out suction filtration, and wash the solid obtained by suction filtration three times with absolute ethanol to obtain the yellow solid product 1,8-naphthalimide-rhodamine fluorescent probe.

[0043] The 1,8-naphthalimide-rhodamine fluorescent probe has remarkable application performance and characteristics in the adsorption capacity for Fe 3+ . Detect the detection ability of this fluorescent probe for metal ions. For Fe 3+ , it shows a linear quenching in the range of 0 - 330 μmol / L, and the detection limit is 0.84 μmol / L.

[0044] See Figure 1 It is the synthesis schematic diagram of the 1,8-naphthalimide-rhodamine fluorescent probe disclosed in the present invention; it can be seen from the figure that rhodamine B undergoes a condensation reaction with anhydrous ethylenediamine to obtain the ring-closed rhodamine B ethylenediamine intermediate, and then undergoes a further condensation reaction with 1,8-naphthalic anhydride to obtain the 1,8-naphthalimide-rhodamine fluorescent probe.

[0045] See Figure 2 It is the nuclear magnetic resonance spectrum of the 1,8-naphthalimide-rhodamine fluorescent probe prepared in Example 1 of the present invention; among them, (a) is the hydrogen spectrum and (b) is the carbon spectrum; it can be seen from the figure that the specific analysis of the hydrogen spectrum and carbon spectrum of the nuclear magnetic structure of the 1,8-naphthalimide-rhodamine fluorescent probe is as follows:

[0046] 1 H NMR(600MHz,Chloroformd)δ8.40(dd,J=7.3,1.1Hz,2H),8.05(d,J=8.1Hz,2H),7.84(dd,J=6.6,2.0Hz,1H),7.60(t,J=7.7Hz,2H),7.39–7.26(m,2H),6.98–6.87(m,1H),6.37(d,J=8.8Hz,2H),6.23(d,J=2.6Hz,2H),5.86(dd,J=8.9,2.6Hz,2H),4.18(t,J=6.0Hz,2H),3.44(t,J=5.9Hz,2H),3.15–2.98(m,8H),1.18(q,J=8.0,7.0Hz,1H),1.00(t,J=7.0Hz,12H).

[0047] 1313C NMR (151 MHz, CDCl3) δ 168.68, 164.01, 153.63, 153.41, 148.41, 133.27, 132.12, 131.50, 130.78, 128.89, 128.29, 127.83, 126.71, 123.80, 123.11, 122.91, 107.89, 105.78, 97.77, 77.23, 77.02, 76.81, 65.22, 44.20, 39.29, 39.17, 12.64.

[0048] It is completely consistent with the structure of the standard product. Therefore, the 1,8-naphthalimide-rhodamine fluorescent probe in the present invention is successfully prepared.

[0049] See Figure 3 It is the fluorescence response diagram of the 1,8-naphthalimide-rhodamine fluorescent probe prepared in Example 1 of the present invention for different metal ions; it can be seen from the figure that only Fe causes a significant decrease in the fluorescence intensity of the 1,8-naphthalimide-rhodamine fluorescent probe after adding many metal ions. Therefore, the probe prepared in the present invention can selectively recognize Fe 3+ causing a significant decrease in the fluorescence intensity of the 1,8-naphthalimide-rhodamine fluorescent probe. Therefore, the probe prepared in the present invention can selectively recognize Fe 3+ for selective recognition.

[0050] Example 2

[0051] A preparation method of a 1,8-naphthalimide-rhodamine fluorescent probe, comprising the following steps:

[0052] 1) By mass, first take 1.0 part of rhodamine B and dissolve it in 20 parts of ethanol, then take 2.5 parts of anhydrous ethylenediamine and dropwise add it to the above solution, and heat and reflux the reaction at 70 °C for 7 h; after the reaction is completed, rotate and evaporate to remove the solvent at 60 °C to obtain a pink substance, then add 32 parts of dichloromethane to it, dissolve it, extract it repeatedly 8 times with 20 mL of distilled water, collect the organic phase and add 20 parts of anhydrous sodium sulfate to absorb water, and then rotate and evaporate to remove the solvent to obtain a red rhodamine B ethylenediamine intermediate;

[0053] 2) By mass, take 0.3 part of the rhodamine B ethylenediamine intermediate prepared in step 1 and dissolve it in 20 parts of ethanol, take 0.2 part of 1,8-naphthalic anhydride and dissolve it in 8 parts of ethanol, and dropwise add it to the above solution under stirring conditions, and react at 55 °C for 6 h; after the reaction is completed, let the solution stand for 9 h to recrystallize the product therein, then perform suction filtration, and wash the solid obtained by suction filtration three times with anhydrous ethanol to obtain a yellow solid product of 1,8-naphthalimide-rhodamine fluorescent probe.

[0054] The 1,8-naphthalimide-rhodamine fluorescent probe has remarkable application performance and characteristics for Fe 3+adsorption capacity. The detection ability of this fluorescent probe for metal ions was detected. For Fe 3+ showed a linear quenching in the range of 0 - 330 μmol / L, and the detection limit ranged from 0.89 μmol / L.

[0055] Example 3

[0056] A preparation method of a 1,8-naphthalimide-rhodamine fluorescent probe, comprising the following steps:

[0057] 1) By mass, first weigh 1.2 parts of rhodamine B and dissolve it in 25 parts of ethanol, then take 2.4 parts of anhydrous ethylenediamine and add it dropwise to the above solution, and heat and reflux the reaction at 80 °C for 7 h; after the reaction is completed, rotary evaporate to remove the solvent to obtain a pink substance, then add 35 parts of dichloromethane to it, dissolve it, extract it repeatedly with 20 mL of distilled water 8 times, collect the organic phase and add 20 parts of anhydrous sodium sulfate to absorb water, and then rotary evaporate it again to remove the solvent to obtain a red rhodamine B ethylenediamine intermediate;

[0058] 2) By mass, weigh 0.4 parts of the rhodamine B ethylenediamine intermediate prepared in step 1 and dissolve it in 25 parts of ethanol, weigh 0.18 parts of 1,8-naphthalic anhydride and dissolve it in 10 parts of ethanol, and add it dropwise to the above solution under stirring conditions, and react at 60 °C for 5 h; after the reaction is completed, let the solution stand for 8 h to crystallize the product therein, then perform suction filtration, and wash the solid obtained by suction filtration three times with anhydrous ethanol to obtain a yellow solid product of 1,8-naphthalimide-rhodamine fluorescent probe.

[0059] The 1,8-naphthalimide-rhodamine fluorescent probe has remarkable application performance and characteristics in terms of the adsorption capacity for Fe 3+ . The detection ability of this fluorescent probe for metal ions was detected. For Fe 3+ showed a linear quenching in the range of 0 - 330 μmol / L, and the detection limit ranged from 0.90 μmol / L.

[0060] Example 4

[0061] A preparation method of a 1,8-naphthalimide-rhodamine fluorescent probe, comprising the following steps:

[0062] 1) By mass, first weigh 1.4 parts of rhodamine B and dissolve it in 30 parts of ethanol, then take 2.8 parts of anhydrous ethylenediamine and add it dropwise to the above solution, and heat and reflux the reaction at 80 °C for 8 h; after the reaction is completed, rotary evaporate to remove the solvent to obtain a pink substance, then add 37 parts of dichloromethane to it, dissolve it, extract it repeatedly with 20 mL of distilled water 9 times, collect the organic phase and add 25 parts of anhydrous sodium sulfate to absorb water, and then rotary evaporate it again to remove the solvent to obtain a red rhodamine B ethylenediamine intermediate;

[0063] 2) Weigh 0.4 parts of the rhodamine B ethylenediamine intermediate prepared in step 1) and dissolve it in 30 parts of ethanol. Weigh 0.2 parts of 1,8-naphthalic anhydride and dissolve it in 10 parts of ethanol. Under stirring conditions, add it dropwise to the above solution and react at 60 °C for 6 h. After the reaction is completed, let the solution stand for 8 h to allow the product to recrystallize and precipitate, then perform suction filtration, and wash the solid obtained by suction filtration three times with anhydrous ethanol to obtain the yellow solid product 1,8-naphthalimide-rhodamine fluorescent probe.

[0064] The 1,8-naphthalimide-rhodamine fluorescent probe has remarkable application performance and characteristics in the adsorption capacity for Fe 3+ . Detect the detection ability of this fluorescent probe for metal ions. For Fe 3+ , it shows linear quenching in the range of 0 - 330 μmol / L, and the detection limit range is 0.91 μmol / L.

[0065] Example 5

[0066] A preparation method of 1,8-naphthalimide-rhodamine fluorescent probe includes the following steps:

[0067] 1) Weigh 1.5 parts of rhodamine B and dissolve it in 30 parts of ethanol by mass. Then take 3 parts of anhydrous ethylenediamine and add it dropwise to the above solution, and heat and reflux at 85 °C for 6 h. After the reaction is completed, rotate and evaporate to remove the solvent to obtain a pink substance. Then add 40 parts of dichloromethane to it, dissolve it, extract it repeatedly 9 times with 20 mL of distilled water, collect the organic phase and add 25 parts of anhydrous sodium sulfate to absorb water, and then rotate and evaporate to remove the solvent to obtain the red rhodamine B ethylenediamine intermediate.

[0068] 2) Weigh 0.6 parts of the rhodamine B ethylenediamine intermediate prepared in step 1) and dissolve it in 30 parts of ethanol by mass. Weigh 0.24 parts of 1,8-naphthalic anhydride and dissolve it in 10 parts of ethanol. Under stirring conditions, add it dropwise to the above solution and react at 65 °C for 7 h. After the reaction is completed, let the solution stand for 12 h to allow the product to recrystallize and precipitate, then perform suction filtration, and wash the solid obtained by suction filtration three times with anhydrous ethanol to obtain the yellow solid product 1,8-naphthalimide-rhodamine fluorescent probe.

[0069] The 1,8-naphthalimide-rhodamine fluorescent probe has remarkable application performance and characteristics in the adsorption capacity for Fe 3+ . Detect the detection ability of this fluorescent probe for metal ions. For Fe 3+ , it shows linear quenching in the range of 0 - 330 μmol / L, and the detection limit range is 0.95 μmol / L.

[0070] Comparative example

[0071] Yulong Kang et al. prepared a novel colorimetric fluorescent probe using rhodamine 6G for Fe 3+ The detection limit was 3.87 μmol / L (Kang Yulong, Bai Tonglu, Han Bo, et al. A rhodamine 6G-based "Off-On" type Fe 3+ colorimetric fluorescent probe [J]. Chemical Bulletin, 2023, 86(1): 8.).

[0072] Table 1 Comparison of the detection limits of the 1,8-naphthalimide-rhodamine fluorescent probes prepared in Examples 1-5 for Fe 3+ with those of the comparative examples

[0073] Example Detection limit (μmol / L) Example 1 0.84 Example 2 0.89 Example 3 0.90 Example 4 0.91 Example 5 0.95 Control example 3.87

[0074] Referring to Table 1 for the comparison of the detection limits of the 1,8-naphthalimide-rhodamine fluorescent probes prepared in Examples 1-5 for Fe 3+ It can be seen from the table that the detection limit of the 1,8-naphthalimide-rhodamine fluorescent probe prepared by the present invention for Fe 3+ is much lower than that of the comparative example.

[0075] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A 1,8-naphthalimide-rhodamine fluorescent probe, characterized in that, The structural formula of the 1,8-naphthalimide-rhodamine fluorescent probe is as follows: 。 2. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 1, characterized in that, It includes the following steps: 1) Dissolve rhodamine B in ethanol, then add anhydrous ethylenediamine. After heating under reflux and rotary evaporation, add dichloromethane. After extraction, collect the organic phase and add anhydrous sodium sulfate. After rotary evaporation, obtain the rhodamine B ethylenediamine intermediate; 2) Dissolve the rhodamine B ethylenediamine intermediate prepared in step 1) in ethanol, then add the 1,8-naphthalic anhydride solution. After the reaction is completed, let it stand. After the product recrystallizes and precipitates, filter it by suction and wash it to obtain the 1,8-naphthalimide-rhodamine fluorescent probe.

3. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, wherein In step 1), the mass ratio of rhodamine B:ethanol:anhydrous ethylenediamine:dichloromethane:anhydrous sodium sulfate is (1.0~1.5):(20~30):(2~3):(30~40):(20~25).

4. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, characterized in that, In step 1), the conditions for the heating reflux reaction are: react at 70~85 °C for 6~8 h.

5. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, wherein In step 1), the number of extraction times is 8~9 times.

6. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, characterized in that, In step 2), the 1,8-naphthalic anhydride solution is prepared by dissolving 1,8-naphthalic anhydride in ethanol, and the mass ratio of 1,8-naphthalic anhydride:ethanol is (0.12~0.24):(5~10).

7. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, characterized in that, In step 2), the mass ratio of rhodamine B ethylenediamine intermediate:1,8-naphthalic anhydride is (0.3~0.6):(0.12~0.24).

8. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, characterized in that, In step 2), the reaction conditions are: react at 55~65 °C for 5~7 h.

9. The preparation method of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 2, wherein In step 2), the standing time is 8~12 h.

10. Use of the 1,8-naphthalimide-rhodamine fluorescent probe according to claim 1 in the preparation of a reagent for trace detection and content analysis of metal ions, characterized in that, This 1,8-naphthalimide-rhodamine fluorescent probe quenches linearly for Fe 3+ in the range of 0 - 330 μmol / L, and the detection limit ranges from 0.84 to 0.95 μmol / L.

Images