CN107827825B - Synthesis and application of benzimidazolyl supramolecular gelator based on hydroxynaphthalene formaldehyde functionalization - Google Patents

Abstract

The benzimidazolyl supramolecular gelator based on the functionalization of hydroxynaphthalene formaldehyde is designed and synthesized, and in the molecules of the gelator, benzimidazole serves as a system with stable rigid structure, so that the main molecules emit strong fluorescence; the naphthalene ring is used as a signal reporting group, so that the host molecule has good aggregation state fluorescence performance, and the water solubility of the sensor molecule is enhanced. Organogel formed by the gelator in organic solvent is used for treating Fe³⁺、Al³⁺And CN^‑Has single selective fluorescence recognition performance. The organogel and iron ions are combined to form metal organogel, and the metal organogel can further remove binding force to identify L-cysteine, so that the fluorescence of a gel factor is recovered, and the OFF-ON signal of a sensor molecule is reflected. The synthesis of such "ON-OFF-ON" type sensor molecules enables multifunctional applications of the sensor.

Description

A kind of benzimidazole-based supramolecular gelling factor based on hydroxynaphthaldehyde functionalized Synthesis and Application

technical field

The invention relates to a benzimidazole-based supramolecular gel factor, in particular to a benzimidazole-based supramolecular gel factor based on hydroxynaphthalene formaldehyde functionalization and a synthesis method thereof; the invention also relates to the supramolecular gel at the same time The application of the factor in colorimetric-fluorescence identification of iron ion and L-cysteine, aluminum ion and cyanide belongs to the field of ion detection.

Background technique

Iron is one of the essential trace elements for the human body. Iron is involved in the synthesis of myoglobin, cytochrome, hemoglobin, cytochrome oxidase and catalysts, while iron affects the metabolism of proteins and hematopoietic vitamins and the synthesis of deoxyribonucleic acid. Because iron is involved in hematopoietic function and the relationship between iron and enzymes, it is determined that iron deficiency can reduce the bactericidal ability of white blood cells, increase the infectivity of the body, and damage the function of lymphocytes, resulting in reduced immunity. Lack of iron in the body can generally cause problems such as lymphomegaly, iron-deficiency anemia, and edema of the extremities. The detection of iron ions is of great significance in the fields of environmental detection and life science.

Amino acids are the basic units of protein, so the importance of amino acids to the human body is self-evident. There are 22 kinds of amino acids, and 8 kinds of amino acids are necessary for the human body. The efficacy and role of each amino acid are different. For the treatment and prevention of different diseases, different amino acids should be selected for supplementation. L-cysteine is an amino acid with physiological functions. It is the only amino acid with a reducing group sulfhydryl (-SH) among more than 20 amino acids that make up proteins. It has been widely used in medicine, food additives and cosmetics. . Therefore, the detection of L-cysteine is equally important in the fields of life science and production.

In industrial production, cyanide is widely used in gold mining, electroplating, metallurgy, etc., and plays a very important role. However, cyanide is a highly toxic chemical in living organisms and the environment, especially for mammals. Cyanide can be immersed in organisms through the respiratory tract, esophagus and skin and cause poisoning. In mild cases, there are mucosal irritation symptoms, numbness of the lips and tongue, asthma, nausea, vomiting, and palpitations. In severe cases, irregular breathing, gradual coma, rapid breathing disorder and death. According to the data of the World Health Organization (WHO), the content of cyanide in drinking water should not exceed 19 μmol/L at most. Therefore, it is necessary to selectively detect trace amounts of cyanide in a simple and intuitive way.

Aluminum products are very common in daily life, such as drinking bottles, kitchen items, food additives and aluminum-based medicines. Also, due to acid rain, more aluminum ions flow into water resources. So people can easily get excess aluminum ions from water and food. However, aluminum ions are neurotoxic to living bodies. Aluminum ions are known to be associated with Alzheimer's disease, Parkinson's disease, smoking-related diseases and age spots.

In view of the wide application of chemical sensors in environmental science and life science, the design and synthesis of chemical sensors has attracted more and more attention in recent years. Designing and synthesizing chemical sensors that can rapidly and specifically recognize specific ions has always been a research hotspot. So far, many probes that can single-recognize iron ions and cysteine have been reported. However, there are few reports using the same sensor molecule to recognize iron ions and cysteine in a continuous relay. In addition, ion-responsive organogels have become a new research hotspot in the field of ion recognition due to their easy preparation and ease of use. Therefore, the development of an organogel that can continuously recognize iron ions and L-cysteine, aluminum ions and cyanide groups has important application prospects.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a benzimidazole-based supramolecular gel factor based on hydroxynaphthalene carboxaldehyde functionalization and a synthetic method thereof;

Another object of the present invention is to provide a kind of organogel based on above-mentioned supramolecular gel factor and preparation method thereof;

Another object of the present invention is to provide a specific application of an organogel based on the above-mentioned gelling factor in the colorimetric-fluorescence identification of iron ion and L-cysteine, aluminum ion and cyanide.

1. Benzimidazole-based supramolecular gelling factor based on functionalized hydroxynaphthalene formaldehyde

The molecular formula of the supramolecular gel factor of the present invention is: C ₃₁ H ₃₈ N ₄ O ₂ , named as: N'-((2-hydroxynaphthalen-1-yl)methylene)-2-(2-undecane) Alkyl-1H-benzimidazol-1-yl) acetyl hydrazide, marked as: S, its structural formula is:

。

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Preparation of supramolecular gel factor S: using absolute ethanol as solvent, glacial acetic acid as catalyst, 2-undecyl-1H-benzimidazolyl-1-acetylhydrazide and 2-hydroxy-1-naphthaldehyde as 1 : 2~1:10 molar ratio, react at 80~90 ℃ for 8~10h; after the reaction, cool to room temperature, remove the solvent by suction filtration, and recrystallize with DMF-EtOH to obtain a light yellow solid product, which is the sensor molecule S . The amount of glacial acetic acid is 1 to 5 times the total molar amount of the substrate. The mass spectrum of sensor molecule S is shown in Figure 1.

A rigid structural group benzimidazole and a signal reporting group naphthalene ring are introduced into the molecule of the supramolecular gelling factor of the present invention, so that the gelling factor has good aggregated fluorescence properties and enhances the water solubility of the sensor molecule.

2. Organogels based on supramolecular gelling factors

The organogel based on supramolecular gelling factor S is the gelling factor S(N'-((2-hydroxynaphthalen-1-yl)methylene)-2-(2-undecyl-1H- Benzimidazol-1-yl) acetohydrazide) was dissolved in an organic solvent, and after cooling to room temperature, an organic gel was formed, denoted as OG.

Wherein, the organic solvent is ethylene glycol or glycerol; the mass-volume ratio of the gelling factor S to the organic solvent is 5-30 mg/ml.

The research on the gelation ability of gelling factor S in different organic solvents shows that gelling factor S can form a stable organogel system in both ethylene glycol and glycerol. The organic solvent is preferably glycerol due to its higher remelting temperature in glycerol. In the following series of studies, an organogel OG with a mass-to-volume ratio of 5-30 mg/ml in glycerol was selected for research.

3. Application of Organogel OG in Ion Detection

1. Fluorescence properties of organogel OG

Figure 2 is the fluorescence emission spectrum of the organogel OG formed by gelling factor S in glycerol. It can be seen from Figure 2 that the organogel OG has good fluorescence emission properties. When the excitation wavelength is 420 nm, the organogel OG emits yellow fluorescence (emission wavelength 525 nm).

2. Response of Organogel OG to Cation

Mg ²⁺ , Ca ²⁺ , Cr ³⁺ , Fe ³⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ² were added to the organogel OG in 2-fold molar amounts (relative to the sensor molecule S), respectively. ⁺ , Ag ⁺ , Cd ²⁺ , Hg ²⁺ , Pb ²⁺ , Ba ²⁺ , Tb ³⁺ , Al ³⁺ , La ³⁺ and Eu ³⁺ aqueous solution (concentration 0.1M), it was observed that only Fe The addition of ³⁺ can cause the fluorescence quenching of the organogel OG (see Figure 3), while the addition of other cations cannot produce similar fluorescence quenching performance, therefore, the organogel OG can achieve a single selective response to Fe ³⁺ .

At the same time, it is found that only the addition of Al ³⁺ can change the fluorescence color of the organogel OG from yellow to blue, while the addition of other cations does not change the fluorescence of the organogel OG (see Figure 4). Therefore, therefore, Organogel OG can achieve single selective recognition of Al ³⁺ .

3. Response of Organogel OG to Anions

F ^- , Cl ^- , Br ^- , I ^- , AcO ^- , HSO ₄ ^- , H ₂ PO ₄ ^- , N ₃ ^- , S ^2- , SCN ^- , ClO were added to the organogel OG at a concentration of 0.1M. ₄ ^- , CN ^- aqueous solution, it was found that only the addition of CN ^- , the fluorescence color of the organogel OG changed from yellow to blue (see Figure 5), while the addition of other anions, the fluorescence of the organogel OG did not change. Therefore, the organogel OG can achieve a single selective recognition ^of CN-.

4. Metal-organic gels based on gelling factor S

In the organogel OG with a mass-to-volume ratio of 5-30 mg/ml, Fe(III) salt in an amount of 0.5-5 times the molar amount of the organogel is added, and it diffuses freely until the fluorescence of the organogel OG is completely quenched, that is, the metal is formed. Organogel FeG.

5. Application of metal organogel FeG in the detection of L-cysteine

20 times molar amount (relative to Fe ³⁺ ) of L-Leu, L-Pro, L-Ary, L-Ser, L-Thr, L-Phe, L-Gln, L -IIe, L-Glu, L-Ala, L-Met, L-Val, L-Tyr, DL-Asp, L-His, L-Gly and L-Cys in water (at 0.1 M concentration), observed metal-organic Gel FeG responses to various amino acids. It was found that only the addition of L-Cys could restore the fluorescence of the metal-organic gel FeG, and the color of the metal-organic gel was restored from black to light yellow. The addition of other amino acids had no obvious effect on the fluorescence of metal-organic gel FeG. Therefore, the metal organogel FeG can achieve a single selective recognition of L-Cys. It also shows that the organogel OG can continuously recognize Fe ³⁺ and L-Cys by fluorescence. Fluorescence spectra when 2 moles of Fe ³⁺ (relative to the sensor molecule S) were added to the organogel OG and 20 moles of L-Cys (relative to Fe ³⁺ ) were added to the metal-organogel FeG (see Figure 3: Excitation wavelength 420nm, emission wavelength 536nm).

In order to study the existence state of organogel OG and metal-organogel FeG, scanning electron microscope (SEM) was performed (organogel OG-0.5%). The SEM was carried out under the condition that the organogel OG and metal-organogel FeG were sprayed with gold. The results are shown in Fig. 6. It was found that the organogel OG existed in an overlapping concave-convex nanopore structure. When Fe ³⁺ was added to it to form the metal-organogel FeG, its nanopore-like structure transformed into a lamellar structure. However, when L-Cys was added to the metal-organic gel FeG, L-Cys competed to bind Fe ³⁺ , so that the lamellar structure was transformed into a wrinkled structure.

To sum up, the present invention designs and synthesizes a benzimidazole-based supramolecular gel factor based on hydroxynaphthalene carboxaldehyde functionalization. The molecule emits strong fluorescence; the naphthalene ring acts as a signal reporting group, which makes the host molecule have good aggregated fluorescence properties and enhances the water solubility of the sensor molecule. The organic gel formed by the gelling factor in organic solvent has single selective fluorescence recognition performance for Fe ³⁺ , Al ³⁺ and CN ^- . After the organogel is combined with iron ions to form a metal organogel, it can further de-relay and recognize L-cysteine, causing the fluorescence recovery of the gel factor, and realizing the “OFF-ON” signal of the sensor molecule. The synthesis of this "ON-OFF-ON" type sensor molecule enables the multifunctional application of the sensor.

Description of drawings

Fig. 1 is the mass spectrum of gel factor S prepared by the present invention.

Figure 2 is the fluorescence emission spectrum of organogel OG in glycerol.

Figure 3 shows the fluorescence spectra (excitation wavelength 420 nm, emission wavelength 536 nm) when 2 times molar amount of Fe ³⁺ (a) is added to organogel OG and 20 molar amount of L-Cys (b) is added to metal organogel FeG.

Figure 4 is the fluorescence spectrum (excitation wavelength 420nm) when 2 times molar amount of Al ³⁺ is added to the organogel OG.

Figure 5 is the fluorescence emission spectrum (excitation wavelength 420nm) when 20 times the molar amount of CN ^- is added to the organogel OG.

Figure 6 shows the SEM images of 0.5% (m/v) organogel OG, metal organogel FeG and FeG after adding L-Cys.

Detailed ways

The synthesis, organogel and its application in colorimetric/fluorescence identification of iron ion and L-cysteine, aluminum ion and cyanide group of the present invention will be further described below through specific examples.

Example 1. Preparation of gelling factor S

In 30ml of absolute ethanol, add 1.36g (4 × 10 ^-3 mol) 2-undecyl-1H-benzimidazolyl-1-acetylhydrazide, 0.68g 2-hydroxy-1-naphthaldehyde (4 × 10 ^-3 mol), 2 ml of glacial acetic acid, react at 80 °C for 8 h, cool down to room temperature after the reaction is completed, remove the solvent by suction filtration, and recrystallize with DMF-EtOH to obtain a yellow solid product, which is gel factor S; the yield is 78.2%. Its mass spectrum is shown in Figure 1.

Embodiment 2, the preparation of organogel OG

Take 0.005 g of the gelling factor S prepared in Example 1, add it to 1.00 ml of glycerol and heat to fully dissolve it, let it stand, and cool to room temperature to form an organogel OG with a mass-to-volume ratio of 5 mg/ml.

Example 3. Colorimetric/fluorescent recognition of iron ions and L-cysteine by organogel OG

Pipette the organogel OG into a series of drip plates, add Mg ²⁺ , Ca ²⁺ , Cr ³⁺ , Fe ³⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , Ag ⁺ , The aqueous solution of Cd ²⁺ , Hg ²⁺ , Pb ²⁺ , Ba ²⁺ , Tb ³⁺ , Al ³⁺ , La ³⁺ and Eu ³⁺ cations (concentration 0.1M), if the fluorescence of organogel OG is quenched , and the color of the gel changes from yellow to black, it means that Fe ³⁺ is dripped. If the fluorescence of the organogel does not quench, it means that it is not Fe ³⁺ .

Pipette the metal-gel FeG formed by adding Fe ³⁺ organogel into a series of drip plates, add L-Leu, L-Pro, L-Ary, L-Ser, L-Thr, L- Aqueous solutions of Phe, L-Gln, L-IIe, -Glu, L-Ala, L-Met, L-Val, L-Tyr, DL-Asp, L-His, L-Gly, L-Cys (concentration 0.1 M), if the fluorescence of the metal-organic gel FeG recovers and the gel color recovers from black to light yellow, it means that L-Cys is added. If the fluorescence of the metal-organic gel does not change, it means that it is not L-Cys Cys.

Example 4. OG colorimetric/fluorescence identification of aluminum ions

Pipette the organogel OG into a series of drip plates, add Mg ²⁺ , Ca ²⁺ , Cr ³⁺ , Fe ³⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , Ag ⁺ , The aqueous solution of Cd ²⁺ , Hg ²⁺ , Pb ²⁺ , Ba ²⁺ , Tb ³⁺ , Al ³⁺ , La ³⁺ , Eu ³⁺ (concentration is 0.1M), if the fluorescence color of the organogel changes from yellow If it is blue, it means that Al ³⁺ is dripped. If the fluorescence of the organogel does not change, it means that it is not Al ³⁺ .

Embodiment 5, OG colorimetric/fluorescence recognition CN ^-

Pipette the organogel OG into a series of drip plates, add F ^- , Cl ^- , Br ^- , I ^- , AcO ^- , HSO ₄ ^- , H ₂ PO ₄ ^- , N ₃ ^- , S ^2- , SCN ^- , ClO ₄ ^- , CN ^- aqueous solution (concentration is 0.1M), if the fluorescence color of the organogel changes from yellow to blue, it means that CN ^- is added dropwise; if the fluorescence of the organogel does not change, it means that It is not CN ^- that is added dropwise.

Claims (1)

1. The application of benzimidazolyl supermolecule organogel based on hydroxynaphthalene formaldehyde functionalization in cyanogen identification is characterized in that: transferring the organogel into a series of drop plates, and adding F^-，Cl^-，Br^-，I^-，AcO^-，HSO₄ ^-，H₂PO₄ ^-，N₃ ^-，S^2-，SCN^-，ClO₄ ^-、CN^-If the fluorescence color of the organogel changes from yellow to blue, the aqueous solution of (1) indicates that CN is added dropwise^-(ii) a If the fluorescence of the organogel is not changed, it indicates that the dropwise addition is not CN^-；

The organic gel is prepared by dissolving the supramolecular gelator into glycerol to form a solution with the mass-volume ratio of 5 ~ 30mg/ml, and cooling to room temperature to form stable condensed organic gel, wherein the structural formula of the supramolecular gelator is as follows:

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