A phenanthroline compound, its preparation method and application

Abstract

This invention discloses an o-phenanthroline compound, its preparation method, and its application, belonging to the field of copper ion detection technology. The o-phenanthroline compound has the structure shown in formula (I): wherein R1 and R2 are the same or different, and each is an independent hydrophilic group. The compound provided by this invention has high fluorescence quantum yield and can sensitively detect copper ions in aqueous solution.

Description

Technical Field

[0001] This invention relates to an o-phenanthroline compound, its preparation method, and its application, specifically relating to the field of copper ion detection technology. Background Technology

[0002] Copper ions are the third most abundant element in biological and ecological systems after iron and zinc ions. They play a vital role in organisms and the environment. Trace amounts of copper ions can promote the growth of plants and animals, but when they accumulate to a certain level through ecological processes, they can cause varying degrees of damage, leading to physiological impairment, developmental arrest, and even death. Excessive copper ions can also affect and damage the function, structure, and development trend of the entire aquatic ecosystem, even causing its collapse. Therefore, the detection of copper ions in water bodies is crucial.

[0003] Currently, new copper reagent is a commonly used colorimetric reagent that selectively responds to copper ions, but the sensitivity of ultraviolet-visible absorption spectroscopy is lower than that of fluorescence spectroscopy.

[0004] The core principle of fluorescence-based detection of copper ions is the interaction between a fluorescent probe and copper ions, leading to a change in the fluorescence signal, thereby enabling the detection of copper ions. This method has advantages such as high sensitivity, simple operation, and fast response. Currently, specific methods include the following:

[0005] (1) Amino-functionalized zirconium dioxide nanotube array thin film method: This method uses amino-functionalized zirconium dioxide nanotube array thin film as a carrier and Rhodamine B as a fluorescent probe. Copper ions and Rhodamine B are immobilized on the carrier to prepare a detection sample. The detection of copper ions is achieved by testing the fluorescence intensity of the detection sample.

[0006] (2) Peptide fluorescence sensor method: Based on the fluorescence quenching effect of copper ions on rhodamine B-labeled peptides, a fluorescence sensor for copper ion detection was constructed.

[0007] (3) Functionalized carbon quantum dot method: Detection of copper ions using the fluorescence properties of functionalized carbon quantum dots. This method achieves sensitive detection of copper ions by the interaction between carbon quantum dots and copper ions, which leads to changes in the fluorescence signal.

[0008] Therefore, it is necessary to provide a new copper ion detection compound that can detect copper ions with high sensitivity and high fluorescence quantum yield during the detection process. Summary of the Invention

[0009] One of the objectives of this invention is to provide an o-phenanthroline compound with high fluorescence quantum yield.

[0010] A second objective of this invention is to provide a method for synthesizing o-phenanthroline compounds. This method involves first oxidizing 2,9-dimethyl-1,10-phenanthroline with an oxidizing agent to convert the two methyl groups into aldehyde groups; then reacting the intermediate from the previous step with a compound of formula (2) containing a thiol group and an amino group to obtain the o-phenanthroline compound. This synthetic method features mild reaction conditions, simple process, good selectivity, high yield, and is conducive to industrial production.

[0011] A third objective of this invention is to provide the application of o-phenanthroline compounds in the detection of copper ions. These compounds can sensitively detect copper ions in aqueous solutions, specifically bind to copper ions, exhibit no significant fluorescence quenching when bound to other metals, and demonstrate excellent selectivity.

[0012] To achieve the above objectives, the present invention provides an o-phenanthroline compound having the structure shown in formula (I):

[0013]

[0014] R1 and R2 may be the same or different, and each is an independent hydrophilic group.

[0015] The key technology of this invention lies in the fact that the compound prepared by using 2,9-dimethyl-1,10-phenanthroline as a raw material retains its cavity structure and has a special response to copper ions. Furthermore, a rigid conjugated planar structure is added on the basis of the ortho-phenanthroline structure, which greatly improves the fluorescence yield.

[0016] In a preferred embodiment, R1 and R2 may be the same or different, and each is independently selected from one of the following: C1-C6 alkyl groups containing carboxyl groups, C1-C6 alkyl groups containing hydroxyl groups, C1-C6 alkyl groups containing sulfonic acid groups, -COOH, -OH, and -SO3H.

[0017] In a more preferred embodiment, R1 and R2 may be the same or different, each independently being -COOH or -OH. The inventors of this invention have discovered that, under these preferred conditions, the o-phenanthroline compounds provided by this invention exhibit better hydrophilicity. The length of the carbon chain attached to the hydroxyl or carboxyl group affects the hydrophilicity of the o-phenanthroline compounds; the fewer the number of carbon atoms, the better the hydrophilicity of the o-phenanthroline compounds. The o-phenanthroline compounds exhibit the best hydrophilicity when R1 and R2 groups are -COOH or -OH.

[0018] In the preferred embodiment, the compound represented by formula (I) is selected from any one of the following compounds:

[0019]

[0020] The inventors of this invention have discovered that when the o-phenanthroline compound is selected from compound 1 or compound 2, its fluorescence intensity is stronger, its selectivity for copper ions is better, and its water solubility is also the strongest.

[0021] The present invention also provides a method for preparing o-phenanthroline compounds, the method comprising:

[0022] (1) In the presence of organic solvent I, the compound shown in formula (1) is oxidized with an oxidant to obtain dialdehyde intermediate I;

[0023] (2) In the presence of organic solvent II, the dialdehyde intermediate I is subjected to a cyclization reaction with the compound shown in formula (2) to obtain o-phenanthroline compounds;

[0024]

[0025] In equation (2), R is R1 or R2, and the definitions of R1 and R2 are the same as those of R1 and R2 mentioned above, which are hydrophilic groups.

[0026] In a preferred embodiment, R is selected from one of the following: C1-C6 alkyl groups containing carboxyl groups, C1-C6 alkyl groups containing hydroxyl groups, C1-C6 alkyl groups containing sulfonic acid groups, -COOH, -OH, and -SO3H.

[0027] In the preferred embodiment, the compound represented by formula (2) is The inventors of this invention have discovered that, under preferred conditions, the synthetic yields of o-phenanthroline compounds are higher. This is likely due to the stronger electron-withdrawing ability of this structure, which is more conducive to cyclization reactions.

[0028] In a preferred embodiment, in step (1), the oxidant is selected from at least one of selenium dioxide, manganese dioxide, and chromyl chloride.

[0029] In a preferred embodiment, the oxidation reaction conditions include a temperature of 105–110°C and a time of 2–4 hours.

[0030] In a preferred embodiment, in step (2), the conditions for the ring-condensation reaction include: a temperature of 80–90°C and a time of 6–10 h.

[0031] In a preferred embodiment, in step (1), the molar ratio of the compound represented by formula (1) to the oxidant is 1:1 to 2. The inventors of this invention have found that in this preferred embodiment, the synthesis yield of this invention is higher. If the content of the oxidant is too low, the methyl group in the compound represented by formula (1) cannot be completely oxidized to an aldehyde group. If the content of the oxidant is too high, it will cause the waste liquid to become more toxic or generate carboxyl groups due to excessive oxidation.

[0032] In a preferred embodiment, in step (2), the molar ratio of the dialdehyde intermediate I to the compound shown in formula (2) is 1:2 to 3. Studies have found that if the amount of the compound shown in formula (2) is too low, the dialdehyde intermediate I will not react completely, resulting in a low yield; if the amount is too high, the dialdehyde intermediate I will react completely, but the compound shown in formula (2) will be wasted in excess.

[0033] It should be noted that in step (2), the method further includes purifying the crude product obtained after the ring-condensation reaction. The present invention does not have special requirements for this purification process. To obtain o-phenanthroline compounds with higher purity, according to a preferred embodiment, the purification process includes: purifying the crude product using a silica chromatography column, with dichloromethane-methanol as the eluent.

[0034] In a preferred embodiment, the organic solvent I is selected from 1,4-dioxane and / or propionitrile. All of these organic solvents can readily synthesize o-phenanthroline compounds, with 1,4-dioxane being the optimal organic solvent.

[0035] In a preferred embodiment, the method further includes: first mixing organic solvent I with water in a volume ratio of 92-98:8-2, and then oxidizing the compound shown in formula (1) with an oxidant to obtain dialdehyde intermediate I.

[0036] In a preferred embodiment, the organic solvent II is selected from at least one of ethanol, ethyl acetate, and acetonitrile. All of these organic solvents can be used to successfully synthesize o-phenanthroline compounds, with ethanol being the optimal organic solvent.

[0037] It should be noted that the present invention does not have any special requirements on the amount of organic solvent I and organic solvent II, and any solvent known in the art can be used.

[0038] This invention also provides the application of o-phenanthroline compounds in the detection of copper ions. The o-phenanthroline compounds provided by this invention have a specific response to copper ions.

[0039] Compared with the prior art, the technical solution of the present invention brings the following beneficial technical effects:

[0040] (1) The o-phenanthroline compounds provided by the present invention retain the cavity structure of 2,9-dimethyl-1,10-phenanthroline and have a specific response to copper ions. Furthermore, a rigid conjugated planar structure is added on the basis of the o-phenanthroline structure, which greatly improves the fluorescence yield.

[0041] (2) The addition of hydrophilic groups (carboxyl or hydroxyl groups) to the o-phenanthroline compounds provided by the present invention enhances their water solubility and is more conducive to practical applications.

[0042] (3) The synthesis method has mild reaction conditions, simple process, good selectivity, high yield, and is conducive to industrial production. Detailed Implementation

[0043] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0044] In this invention, This indicates that R can be substituted at any position in the phenyl group that can be substituted.

[0045] In this invention, This indicates that R1 can be substituted at any position on the phenyl group that can be substituted.

[0046] In this invention, This indicates that R2 can be substituted at any position on the phenyl group that can be substituted.

[0047] In this invention, "C1-C6 alkyl group containing a carboxyl group" refers to an alkyl group with a total number of 1-6 carbon atoms, including straight-chain alkyl, branched alkyl, and cycloalkyl, wherein at least one H atom in the C1-C6 alkyl group is substituted with a carboxyl group. For example, 1, 2, 3, or 4 H atoms in the C1-C6 alkyl group are substituted with carboxyl groups, such as -CH2-COOH, -CH2-CH2-COOH, etc. The explanations for "C1-C6 alkyl groups containing hydroxyl groups" and "C1-C6 alkyl groups containing sulfonic acid groups" are similar, except that the groups substituting the H atoms are different, namely hydroxyl and carboxyl groups, respectively.

[0048] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0049] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0050] Preparation Example 1 (Preparation of Compound 1)

[0051] (1) In a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and condenser, 10 mmol of 2,9-dimethyl-1,10-phenanthroline and 15 mmol of selenium dioxide were reacted at 105 °C for 4 h in the presence of 100 mL of 1,4-dioxane solution (1,4-dioxane to water volume ratio of 95:5) to obtain dialdehyde intermediate I;

[0052] (2) In the presence of 100 mL of ethanol, 2 mmol of dialdehyde intermediate I and 4 mmol of... The reaction was carried out at 85 °C for 8 h. The crude product obtained was purified by silica chromatography column with dichloromethane-methanol (10:1, V / V) as the eluent to give compound 1 in a yield of 68% (calculated based on 2,9-dimethyl-1,10-phenanthroline).

[0053] The NMR characterization results of compound 1 are as follows:

[0054] 1 HNMR (CDCl3, 400MHz), δ: 8.77-8.79 (d, 2H), 8.42-8.45 (d, 2H), 8.18-8.20 (d, 2H), 8.15-8.16 (d, 2H), 7.91-7.93 (d, 2H), 7.56-7.59 (d, 2H)

[0055] Preparation Example 2 (Preparation of Compound 2)

[0056] (1) In a three-necked reaction flask equipped with a mechanical stirrer, thermometer, and condenser, 10 mmol of 2,9-dimethyl-1,10-phenanthroline and 10.5 mmol of selenium dioxide were reacted at 110 °C for 2 h in the presence of 100 mL of 1,4-dioxane solution (1,4-dioxane to water volume ratio of 95:5) to obtain dialdehyde intermediate I;

[0057] (2) In the presence of 100 mL of ethanol, 2 mmol of dialdehyde intermediate I and 5 mmol of... The reaction was carried out at 80 °C for 10 h. The crude product was purified by silica chromatography column with dichloromethane-methanol (10:1, V / V) as the eluent to give compound 2 in a yield of 65% (calculated based on 2,9-dimethyl-1,10-phenanthroline).

[0058] The NMR characterization results of compound 2 are as follows:

[0059] 1HNMR (CDCl3, 400MHz), δ: 8.61-8.63 (d, 2H), 8.17-8.19 (d, 2H), 8.03-8.05 (d, 2H), 7.97-7.99 (d, 2H), 7.75-7.77 (d, 2H), 7.41-7.43 (d, 2H)

[0060] Test case

[0061] The selectivity of the compounds prepared in the above preparation examples for metal ions was investigated.

[0062] 0.5 μmol of the compound prepared in the above preparation example was added to 100 mL of different types of metal ions, and the fluorescence intensity of the solution was tested. Specific information is shown in Table 1.

[0063] The fluorescence intensity was measured using a fluorescence spectrophotometer, with λex: 365 nm, λem: 416.6 nm, and a slit width of 2.5 nm.

[0064]

[0065] The data above show that the o-phenanthroline compounds provided by this invention exhibit selective response only to copper ions and no selectivity for other metals. These compounds show high fluorescence intensity and no fluorescence quenching in solutions without copper ions, indicating no response to other metals. However, in solutions containing copper ions, fluorescence quenching occurs, and the fluorescence intensity decreases significantly.

[0066] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A phenanthroline compound, characterized in that: The compound has the structure shown in formula (I): The compound shown in formula (I) is selected from any of the following compounds: 。 2. A method for preparing the o-phenanthroline compound of claim 1, characterized in that: The method includes: (1) In the presence of organic solvent I, the compound shown in formula (1) is oxidized with an oxidant to obtain dialdehyde intermediate I; (2) In the presence of organic solvent II, the dialdehyde intermediate I is subjected to a cyclization reaction with the compound shown in formula (2) to obtain o-phenanthroline compounds; Equation (1), Equation (2), In equation (2), R is -COOH or -OH.

3. The method for preparing o-phenanthroline compounds according to claim 2, characterized in that: In step (1), the molar ratio of the compound represented by formula (1) to the oxidant is 1:1~2; And / or, in step (2), the molar ratio of the dialdehyde intermediate I to the compound shown in formula (2) is 1:2~3.

4. The method for preparing o-phenanthroline compounds according to claim 2 or 3, characterized in that: In step (1), the oxidant is selected from at least one of selenium dioxide, manganese dioxide and chromyl chloride.

5. The method for preparing o-phenanthroline compounds according to claim 2 or 3, characterized in that: The conditions for the oxidation reaction include: a temperature of 105~110℃ and a time of 2~4h.

6. The method for preparing o-phenanthroline compounds according to claim 2 or 3, characterized in that: In step (2), the conditions for the ring-condensation reaction include: a temperature of 80~90℃ and a time of 6~10h.

7. The application of the o-phenanthroline compound of claim 1 in the detection of copper ions.

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