CN101550092B - 2-(hydroxybenzeneimino) methylene-4-(4'-nitrobenzophenone)azo-phenol, preparation and applications - Google Patents

Abstract

The invention provides a compound 2-(hydroxybenzeneimino) methylene-4-(4'- nitrobenzophenone) azo-phenol, which is prepared by the reaction of nitro-salicylaldehyde and aminophenol. The 2-(hydroxybenzeneimino) methylene-4-(4'-nitrobenzophenone) azo-phenol prepared by the invention has remarkable recognition effect to F<-> in acetonitrile solution, when the F<-> is added to the receptor solution, the color of the solution changes from light yellow to purple; when other ions such as negative ions of C1<->, Br<->, I<-> and the like are added, the color of the receptor solution does not change, thereby realizing the selective naked-eye recognition to fluorine ions. The test paper for detecting fluorine ions by qualitative color comparison prepared by the compound can detect the fluorine ions by qualitative color comparison more conveniently, thereby being characterized by simplicity, quick speed, high efficiency, practicality, and the like.

Description

2-(Hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol and its preparation and application

technical field

The invention belongs to the technical field of chemical synthesis, and relates to a compound based on a phenolic hydroxyl group and a Schiff base—2-(hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol ; The present invention also relates to the preparation method of the compound and its application as a colorimetric recognition fluoride ion acceptor.

Background technique

In recent years, the colorimetric detection of anions using synthetic receptors has attracted attention. The method detects the anion qualitatively by utilizing the color change produced when the artificial receptor interacts with the anion, and can also quantitatively detect the content of the anion through corresponding determination. At present, a large number of anion colorimetric recognition receptors have been developed. Among them, many acceptors can selectively and colorimetrically recognize strong basic anions, and the recognition sites are generally provided by structural units containing NH hydrogen bond donors such as urea or thiourea groups, amine groups or amide groups, and guanidine groups. The signaling reporter group is usually a chromophore.

Among many anions, fluoride ion is particularly important due to its special role in many diseases and environmental science. Excess fluorine can lead to fluorosis, but there are still few simple neutral acceptor molecules that can recognize fluoride ions. Therefore, the design and synthesis of anion receptors with simple structure, easy synthesis and selective colorimetric recognition ability for specified anions is a hotspot in the research of host-guest anion recognition.

Contents of the invention

The object of the present invention is to provide a kind of compound---2-(hydroxyphenylimino) methylene-4-(4'-nitrophenyl) azo phenol based on phenolic hydroxyl and Schiff base.

Another object of the present invention is to provide a preparation method of the compound.

Another object of the present invention is to provide the application of the compound as a receptor for colorimetric recognition of fluoride ions.

Another object of the present invention is to provide a test paper for colorimetrically identifying fluoride ions prepared by using the compound.

(1) 2-(hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol

The chemical structural formula of compound 2-(hydroxyphenylimino) methylene-4-(4'-nitrophenyl) azophenol of the present invention is as follows:

R=o-OH _b , the corresponding compound is 2-(2'-hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol a;

R=m-OH _b , the corresponding compound is 2-(3'-hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol b;

R=p-OH _b , the corresponding compound is 2-(4'-hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol c. Its corresponding structural formula is as follows:

(2) Preparation of 2-(hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol

Method 1: Dissolve p-nitroazosalicylaldehyde in absolute ethanol, add 1-1.2 times the molar amount of p-nitroazosalicylaldehyde to aminophenol, and react at 60-90°C for 2-4 hours to form a red color Precipitate, stand still, filter with suction, and recrystallize with N,N-dimethylformamide-absolute ethanol mixed solution to obtain the target compound.

In the N,N-dimethylformamide-absolute ethanol mixed solution, N,N-dimethylformamide and absolute ethanol are mixed at a volume ratio of 1:100˜1:150.

Method 2: Place p-nitroazo salicylaldehyde and aminophenol in a molar ratio of 1:1 to 1:1.2 and grind them finely in an agate mortar, add absolute ethanol to make the mixture moist (the amount of ethanol added is: Add 1ml ethanol to 2 grams of the mixture), continue to grind for 0.5-1h, and generate a red solid; when the color of the mixture no longer changes, dry it, and recrystallize it with a mixed solution of N,N-dimethylformamide-absolute ethanol to obtain target compound.

In the N,N-dimethylformamide-absolute ethanol mixed solution, N,N-dimethylformamide and absolute ethanol are mixed at a volume ratio of 1:100˜1:150.

Wherein aminophenol includes o-aminophenol, m-aminophenol, p-aminophenol. When o-aminophenol is used as a raw material, the resulting product is 2-(2'-hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol a; when m-amino When phenol is a raw material, the resulting product is 2-(3'-hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol b; when p-aminophenol is used as a raw material , the resulting product is 2-(4'-hydroxyphenylimino)methylene-4-(4'-nitrophenyl)azophenol c.

The p-nitroazo salicylaldehyde used in the above method can be purchased from the market.

Using method 1 to prepare the target compound, the yield is relatively low and the reaction time is long. However, the yield of the target compound prepared by method 2 is high, the reaction time is short, and the reaction is carried out at room temperature. The synthesis method is simple and easy, and it is more in line with the concept of green synthesis.

(3) Application of compounds as colorimetric recognition of fluoride ion receptors

1. The anion recognition performance of the receptor

Pipette 0.5 mL of the acetonitrile solution (2×10 ^-4 mol·L ^-1 ) of receptors a, b, and c into a series of 10 mL colorimetric tubes. Add 0.5mL acetonitrile solution (0.01mol·L ^-1 ) of tetrabutylammonium salts of F ^- , Cl ^- , Br ^- , I ^- anions respectively, dilute to 5ml with acetonitrile, and the acceptor concentration is 2×10 ^-5 mol·L ^-1 , the anion concentration is 50 times the acceptor concentration. After mixing evenly, let it stand, and observe the response of each receptor to anion.

Experimental results: the color of the solution changed from light yellow to purple when F ^- was added, and the color of the acceptor solution remained unchanged when other ions were added. Therefore, receptors a, b, and c have selective colorimetric recognition ability for fluoride ion in acetonitrile solution.

2. Ultraviolet-visible (UV-vis) spectrum of the interaction between receptors and anions

Measure the UV-vis spectrum of the acetonitrile solution of the above-mentioned receptor and the mixed solution of the receptor and different anions respectively, as shown in Figure 1, in the UV-vis spectrum, the receptor a has a maximum absorption peak at 382nm, when the receptor a When the tetrabutylammonium salt solution of F ^- , Cl ^- , Br ^- , I ^- was added in a, only the addition of fluoride ions significantly reduced the absorption peak of the acceptor at 382nm, and at the same time a new strong absorption appeared at 550nm peak, other anions have no significant effect on the absorption peak of the acceptor. Compound receptors b and c have similar recognition ability to anions as a.

3. UV titration of acceptor

Pipette 2 mL of acceptor a acetonitrile solution (2×10 ^-5 mol·L ^-1 ) into a quartz cuvette, and gradually add F ^- tetrabutylammonium salt in acetonitrile solution (1 mol·L ^-1 ), trace the UV absorption spectrum of the system during the titration at 25°C (acetonitrile is used as a reference). (See Figure 4)

The absorption spectrum measurement shows that: when no anion is added, the acceptor molecule a has an absorption peak at 382nm due to intramolecular charge transfer, and in the acetonitrile solution of the acceptor molecule, Cl ^- , Br ^- , I ^- tetra When the acetonitrile solution of butylammonium salt was used, the color and absorption spectrum of the solution did not change significantly, indicating that this type of acceptor molecule had no obvious effect on these anions. And when the guest anion F ^- is added, the acceptor molecule a changes from light yellow to purple, achieving the effect of naked eye recognition. With the continuous addition of F ^- during the UV titration, the absorption peak at 382nm disappeared, and a new absorption peak appeared at 550nm. It shows that with the addition of F ^- , the H _a and H _b on the phenolic hydroxyl group of the acceptor are captured respectively to form oxygen anions, and the deprotonated product A and the deprotonated product B are formed, so that the charge density of the acceptor molecule increases and the absorption peak turns red shift, red shifted to 556nm. At the same time, there is an obvious isoabsorption point at 444nm. With the progress of titration, the isosbestic point red-shifted to 462nm. There is no obvious isoabsorptive point during this process, indicating that the guest anion first breaks the hydrogen bond in the host molecule, and then the acceptor molecule removes two protons step by step to form a salt anion (see Figure 4).

4. ¹ HNMR titration experiment

In order to clarify the deprotonation interaction between acceptor molecules and anions, ¹ HNMR titration experiments were carried out. Using DMSO-d ₆ as the solvent, we performed the NMR titration of the anion on the acceptor. Take a as an example, prepare 0.5ml 2.5mmol·l ^-1 DMSO-d ₆ solution of a, put it in an NMR tube, first do the hydrogen spectrum of a, and then add tetrabutyl fluoride dropwise to it with a micro-injector The DMSO-d ₆ solution of ammonium chloride was added dropwise from 0.1 times to 12 times of the main body anion concentration by cumulative injection method, and a hydrogen spectrum was done after each drop was fully shaken. Due to the influence of the conjugated system, the chemical shift of the H _b proton of the acceptor molecule a moves to the high field to δ10.31, and the chemical shift of the H _a proton moves to the low field to δ15.31. As the concentration of the tetrabutylammonium salt of ^F- in DMSO-d ₆ solution increases from 0.1 times to 12 times, the proton peak of _Hb completely disappears when the added ^F- is 0.1 times, because _Hb forms a pentad with N The intramolecular hydrogen bond of the ring is relatively rigid and easy to break with the six-membered ring of H _a . Soon the proton peak of H _a completely disappeared. When the F ^- concentration increased to 5 times, a new absorption peak appeared at 14.88. With the continuous addition of F ^- , the new absorption peak gradually shifts to the lower field, and gradually becomes higher. When the concentration of F ^- increases to 8 times, the chemical shift of the new absorption peak is δ15.79, and the final chemical shift is δ16 .12. It shows that the acceptor molecule removes H _b and H _a step by step under the action of fluoride ion, and at the same time generates very stable hydrogen difluoride anion (HF ₂ ^- ) (see Figure 5).

In order to further clarify the deprotonation interaction between acceptor molecules and anions, the following experiments were carried out: Add a certain concentration of NaOH solution to the acceptor a solution, the acceptor solution turned purple, and then added HClO ₄ , the solution returned to acceptor a body color. This proves that the acceptor compound has indeed undergone deprotonation.

To sum up, the compound of the present invention has obvious recognition effect on ^F- , and when ^F- is added, the receptor molecule of this type changes from light yellow to purple, thus realizing the naked-eye detection of ^F- .

(4) Preparation and application of colorimetric identification of fluoride ion test paper

1. Preparation of colorimetric fluoride ion test paper

Soak the filter paper soaked in distilled water and dried in the acetonitrile solution with a concentration of 1.5×10 ^-3 ～2.5×10 ^-3 mol·L ^-1 acceptor compound for 1 to 2 minutes, take it out and dry it to get the colorimetric Identify fluoride ion test paper.

2. Application of colorimetric identification of fluoride ion test paper

Drop a drop of F ^- (0.01mol·L ^-1 ) on the colorimetric fluoride ion test paper, and find that the filter paper appears lavender. Drop a drop of F ^- (0.1mol·L ^-1 ) on another test paper, and the test paper turns dark purple. It can be seen that this method can realize the detection of different concentrations of fluoride ions, and has the characteristics of simplicity, efficiency and practicality.

Description of drawings

Figure 1 is the UV-vis spectrum of acceptor a interacting with various anions in acetonitrile solution (2×10 ^-5 mol·L ^-1 )

Figure 2 is the UV-vis spectrum of acceptor b interacting with various anions in acetonitrile solution (2×10 ^-5 mol·L ^-1 )

Figure 3 is the UV-vis spectrum of acceptor c interacting with various anions in acetonitrile solution (2×10 ^-5 mol·L ^-1 )

Figure 4 is the absorption spectrum of acceptor a in the presence of F ^- in acetonitrile (R=0.992 Ks=5.0×10 ⁵ )

Figure 5 is the ¹ H NMR spectrum of acceptor molecule a in DMSO-d ₆ in the presence of F ^-

Detailed ways

Embodiment 1, the preparation of compound a

Weigh 1mmol of p-nitroazosalicylaldehyde into a 100ml round bottom flask, add 25ml of absolute ethanol as solvent, heat in an oil bath at 60-90°C, reflux until completely dissolved, then add 1mmol of o-aminophenol (m- Aminophenol, p-aminophenol) reacted for 2 to 4 hours, a red precipitate was formed, left to stand, suction filtered, DMF-EtOH (N, N-dimethylformamide and absolute ethanol formed at a volume ratio of 1:150 mixed solution) recrystallization to obtain the target compound a. Yield: 74%.

a: red solid, mp294-296°C; ¹ H NMR (DMSO-d ₆ , 400MHz) δ15.34(s, 1H, OH).10.24(s, H, OH), 9.27(s, 1H, N=CH ); IR (KBr, cm ^-1 )v: 3436(OH), 1616(C=N), 1332(N=N); Anal.Calcd.for C ₁₇ H ₁₄ N ₄ O ₉ (%): C, 60.71; H, 3.60; N, 16.66; Found (%): C, 63.60; H, 5.41; N, 13.50.

The preparation of embodiment 2 compound b

Weigh 1mmol p-nitroazosalicylaldehyde into a 100ml round bottom flask, add 25ml absolute ethanol as solvent, heat in an oil bath at 60-90°C, reflux until completely dissolved, then add 1mmol p-aminophenol to react 2 After ~4 hours, a red precipitate was formed, left to stand, suction filtered, recrystallized from DMF-EtOH (a mixed solution of N,N-dimethylformamide and absolute ethanol at a volume ratio of 1:150), and the target compound b. Yield: 61%.

b: red solid, mp297-299°C; ¹ H NMR (DMSO-d ₆ , 400MHz) δ14.64(s, 1H, OH).9.81(s, 1H, OH), 9.14(s, 1H, N=CH ), IR (KBr, cm ^-1 ) v: 3444 (OH), 1612 (C=N), 1342 (N=N); Anal. Calcd. for C ₁₇ H ₁₄ N ₄ O ₉ (%): C, 60.61; H, 3.10; N, 16.46; Found (%): C, 63.50; H, 5.32; N, 13.40.

Embodiment 3, the preparation of compound c

Weigh 1mmol of p-nitrosazosalicylaldehyde into a 100ml round bottom flask, add 25ml of absolute ethanol as solvent, heat in an oil bath at 60-90°C, reflux until completely dissolved, then add 1mmol of p-aminophenol to react 2 After ~4 hours, a red precipitate was formed, left to stand, suction filtered, recrystallized from DMF-EtOH (a mixed solution of N,N-dimethylformamide and absolute ethanol at a volume ratio of 1:150), and the target compound c. Yield: 54%.

c: Red-brown solid, mp>300°C; ¹ H NMR (DMSO-d ₆ , 400MHz) δ14.27(s, 1H, OH).9.76(s, 1H, OH), 9.14(s, 1H, N= CH), IR (KBr, cm ^-1 ) v: 3445 (OH), 1615 (C=N), 1332 (N=N); Anal. Calcd. for C ₁₇ H ₁₄ N ₄ O ₉ (%): C , 60.41; H, 3.40; N, 16.76; Found (%): C, 63.60; H, 5.23; N, 13.10.

Embodiment 4, the preparation of compound a

Weigh 1mmol of p-nitroazosalicylaldehyde in an agate mortar, grind it finely, add a few drops (about 0.1ml) of absolute ethanol, and then add 1mmol of o-aminophenol, immediately a red solid a (formed b, the reaction of c is relatively slow), continue to grind, and soon the mixture turns from yellow to red. Continue grinding for about 0.5-1 hour, when the color does not change and the powder is no longer wet, it means that the reaction is basically over, and then dry it. DMF-EtOH (a mixed solution of N,N-dimethylformamide and absolute ethanol at a volume ratio of 1:150) was recrystallized to obtain the target compound a with a yield of 86%.

a: red solid; mp294-296°C; ¹ H NMR (DMSO-d ₆ , 400MHz) δ15.34(s, 1H, OH).10.24(s, H, OH), 9.27(s, 1H, N=CH ); IR (KBr, cm ^-1 )v: 3436(OH), 1616(C=N), 1332(N=N); Anal.Calcd.for C ₁₇ H ₁₄ N ₄ O ₉ (%): C, 60.71; H, 3.60; N, 16.66; Found (%): C, 63.60; H, 5.41; N, 13.50.

Embodiment 5, the preparation of compound b

Weigh 1mmol of p-nitroazosalicylaldehyde in an agate mortar, grind it finely, add a few drops (about 0.1ml) of absolute ethanol, then add 1mmol of m-aminophenol, a red solid b is produced, continue grinding , the mixture gradually changed from yellow to red. Continue grinding for about 0.5-1 hour, when the color does not change and the powder is no longer wet, it means that the reaction is basically over, and then dry it. DMF-EtOH (a mixed solution of N,N-dimethylformamide and absolute ethanol at a volume ratio of 1:150) was recrystallized to obtain the target compound b with a yield of 78%.

b: red solid, mp297-299°C; ¹ H NMR (DMSO-d ₆ , 400MHz) δ14.64(s, 1H, OH).9.81(s, 1H, OH), 9.14(s, 1H, N=CH ), IR (KBr, cm ^-1 ) v: 3444 (OH), 1612 (C=N), 1342 (N=N); Anal. Calcd. for C ₁₇ H ₁₄ N ₄ O ₉ (%): C, 60.61; H, 3.10; N, 16.46; Found (%): C, 63.50; H, 5.32; N, 13.40.

Embodiment 6, the preparation of compound c

Weigh 1mmol of p-nitroazosalicylaldehyde in an agate mortar, grind it finely, add a few drops (about 0.1m1) of absolute ethanol, then add 1mmol of p-aminophenol, a red solid c is produced, continue grinding , the mixture gradually changed from yellow to red. Continue grinding for about 0.5-1 hour, when the color does not change and the powder is no longer wet, it means that the reaction is basically over, and then dry it. DMF-EtOH (a mixed solution of N,N-dimethylformamide and absolute ethanol at a volume ratio of 1:150) was recrystallized to obtain the target compound c with a yield of 64%.

c: Red-brown solid, mp>300°C; ¹ H NMR (DMSO-d ₆ , 400MHz) δ14.27(s, 1H, OH).9.76(s, 1H, OH), 9.14(s, 1H, N= CH), IR (KBr, cm ^-1 ) v: 3445 (OH), 1615 (C=N), 1332 (N=N); Anal. Calcd. for C ₁₇ H ₁₄ N ₄ O ₉ (%): C , 60.41; H, 3.40; N, 16.76; Found (%): C, 63.60; H, 5.23; N, 13.10.

Embodiment 7, the preparation of the qualitative detection test paper of acceptor a

Soak the filter paper several times in distilled water and let it dry. The acceptor a was configured as an acetonitrile solution with a concentration of 2×10 ^-3 mol·L ^-1 , and then the prepared filter paper was soaked in the solution. After 2 minutes, take it out and let it dry.

Embodiment 8, the preparation of the qualitative detection test paper of acceptor b

Soak the filter paper several times in distilled water and let it dry. The acceptor b was configured as an acetonitrile solution with a concentration of 2×10 ^-3 mol·L ^-1 , and then the prepared filter paper was soaked in the solution. After 2 minutes, take it out and let it dry.

Embodiment 9, the preparation of the qualitative detection test paper of acceptor c

Soak the filter paper several times in distilled water and let it dry. The acceptor c was configured as an acetonitrile solution with a concentration of 2×10 ^-3 mol·L ^-1 , and then the prepared filter paper was soaked in the solution. After 2 minutes, take it out and let it dry.

Embodiment 10, utilize the qualitative detection test paper of acceptor a, b, c to detect fluoride ion

A drop of F ^- (0.01mol·L ^-1 ) was dropped on the filter paper soaked with receptors a, b, and c respectively, and the filter paper was found to be lavender. The test papers of a and b are all lavender, and the test paper of c is light blue.

A drop of F ^- (0.1mol·L ^-1 ) was dropped on the filter paper soaked with receptors a, b, and c respectively, and the filter paper was found to be lavender. The test papers of a, b and c are all dark purple, while the test paper of c is dark blue.

Claims (2)

1. compound 2-(hydroxybenzeneimino base) methylene radical-4-(4 '-nitrophenyl) azo-group phenol is as the application than colour discrimination fluorion acceptor;

The chemical structural formula of said compound 2-(hydroxybenzeneimino base) methylene radical-4-(4 '-nitrophenyl) azo-group phenol is following:

R=o-OH _b, corresponding compound is 2-(2 '-hydroxybenzeneimino base) methylene radical-4-(4 '-nitrophenyl) azo-group phenol a;

R=m-OH _b, corresponding compound is 2-(3 '-hydroxybenzeneimino base) methylene radical-4-(4 '-nitrophenyl) azo-group phenol b;

R=p-OH _b, corresponding compound is 2-(4 '-hydroxybenzeneimino base) methylene radical-4-(4 '-nitrophenyl) azo-group phenol c.

2. compound 2-(hydroxybenzeneimino base) methylene radical-4-(4 '-nitrophenyl) azo-group phenol is characterized in that: adopt following method to be prepared into than colour discrimination fluorion test paper as than the application of colour discrimination fluorion acceptor according to claim 1: will in zero(ppm) water, soak, to place concentration be 1.5 * 10 to air dried filter paper ^-3～2.5 * 10 ^-3MolL ^-1Soaked in the acetonitrile solution of acceptor compound 1～2 minute, taking-up is dried and is promptly got than colour discrimination fluorion test paper.

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