CN101891642B - Fluorescent compound and application thereof to detection of trace nitrobenzene substances - Google Patents

Abstract

The invention relates to a fluorescent compound and its application in detecting trace amounts of nitrobenzene substances, characterized in that the general formula of the fluorescent compound is: In the formula, n ₁ and n ₃ are positive integers of 1-50, n ₂ is a positive integer of 0-50, and n is any integer greater than or equal to 1. The lower limit of trace nitrobenzene substances can reach 0.1ppm.

Description

A fluorescent compound and its application in detecting trace nitrobenzene substances

technical field

The invention relates to a preparation method of a fluorescent compound and its application in detecting trace nitrobenzene substances, belonging to the field of preparation of organic fluorescent sensor materials.

Background technique

Nitrobenzene substances are important intermediates in the manufacture of dyes, paints, coatings, plastics, explosives and pesticides, but nitrobenzene substances are also a class of toxic pollutants, such as nitrobenzene and nitrotoluene are persistent toxic organic pollutants , can cause methemoglobinemia, hemolysis and liver damage; and chloronitrobenzene is a chemical substance that can cause mutations, cause cancer, and cause deformities. Because nitrobenzene compounds are often left behind or discharged into the environment due to incomplete conversion during the production process, causing harm to the environment. With the rapid development of the fine chemical industry, the demand for nitro-based chemicals is on the rise. According to statistics, 30,000 tons of nitro-benzene-based substances are discharged into the environment every year around the world. This type of compound is an important component of toxic and harmful waste water and waste gas, and is an important indicator of environmental pollution. Therefore, it is very important to analyze nitrobenzene substances in environmental samples, and establishing a simple and easy rapid determination method has become one of the problems to be solved urgently in environmental monitoring work.

At present, the commonly used methods for detecting nitrobenzenes mainly include gas chromatography-mass spectrometry, high performance liquid chromatography, and spectrophotometry. The application of gas chromatography-mass spectrometry usually requires extraction and enrichment of samples before application. The organic solvents used in it will cause secondary pollution to the environment and are not suitable for rapid on-site detection; high-performance liquid chromatography is complicated and cumbersome. The cycle is long; the spectrophotometric method needs to reduce the nitrobenzene substances to aniline substances and then react with N-(1 naphthyl)ethylenediamine chromogen after reacting with diazonium salts. The color reaction is very slow and cannot Meet the rapid determination of the scene. In view of the above research status, it is necessary to develop a new fast and efficient detection method for nitrobenzene substances. Due to the advantages of fast response, simple operation, high selectivity, low detection limit, intuitive and simple signal, small interference and easy identification, the fluorescent sensor is suitable for the detection of nitrobenzene substances.

Generally, most organic fluorescent sensing materials have the phenomenon of fluorescence quenching in the aggregated state, especially for one-dimensional chain or two-dimensional planar conjugated organic molecules, it is easy to form H aggregations arranged face-to-face in the solid state, which increases the excitation. The way of non-radiative dissipation of state energy, so there are different degrees of quenching or no fluorescence in the solid state. However, as a fluorescent sensing material, since the sensing in the solution is mainly limited by the sensing performance of the nearly independent sensing molecules themselves, the two-dimensional or multi-dimensional structure formed by the sensing molecules stacked together in the film reflects properties of the sensing membrane. The migration rate of excitons in the sensing film is much greater than that in the solution, so compared with solution sensing, the performance of the film, including sensing sensitivity and speed, will be greatly due to the sensing performance in the solution. Therefore, it is of great research value and application value to find organic fluorescent sensing materials that can effectively inhibit aggregation-induced fluorescence quenching and have good sensing performance in the solid state.

The fluorescent compound proposed by this application for detecting nitrobenzenes consists of an aromatic structural unit and a carboxylate conjugated to it as a structural unit. Due to steric hindrance, the parent molecule and side chain containing the aromatic structural unit A large angle is formed between the carboxylate units, forming a non-planar structure, so it can effectively reduce the fluorescence quenching phenomenon of the aggregated state of the material. Therefore, the applicant of the present invention believes that the fluorescent compound provided by the present invention not only has a simple synthesis method and strong chemical modification, but also can obtain a series of materials with good solid-state luminescent properties by introducing aromatic functional groups of different structures or increasing the length of the conjugated chain. The provided fluorescent compound material is expected to have electrostatic interaction with nitrobenzene substances to cause fluorescence quenching, thereby forming the concept of the present invention.

Contents of the invention

The object of the present invention is to provide a fluorescent compound and its application in detecting nitrobenzene substances. The preparation method of the fluorescent compound described in the invention is simple, high in yield, easy to separate and high in purity, the obtained fluorescent compound has a sensitive response to nitrobenzene substances, and can quickly and accurately detect the nitrobenzene substances in the gas phase.

A class of fluorescent compounds provided by the present invention is characterized in that it contains an aromatic ring and/a carboxylate compound that is directly or conjugated to the aromatic ring, and its general structural formula is as follows:

Where n ₁ and n ₃ are positive integers of 1-50, n ₂ is a positive integer of 0-50, n is any integer greater than or equal to 1, can be infinite, but is usually a positive integer of 1-1000. _R1 and _R2 are triphenylamine, benzene, naphthalene, anthracene, pyrene, fluorene, dinaphthyl, carbazole, quinoline, imidazole, rhodamine and other fluorescent substituents, respectively. That is, R ₁ and R ₂ are one of the above-mentioned 11 fluorescent substituents; the fluorescent substituents R ₁ and R ₂ may be the same or different.

The fluorescent compound responding to nitrobenzene substances has higher fluorescence quantum efficiency in solution and film. In the absence of nitrobenzene substances, the fluorescence of its film or powder is stable; in the presence of nitrobenzene substances, its fluorescence changes, generally manifested as quenching. According to the change of its fluorescence intensity, the detection of aniline compounds can be realized.

The compound with fluorescence response to nitrobenzene is characterized in that the interaction between the fluorescent compound and nitrobenzene is intermolecular force, mainly electrostatic interaction and hydrophobic-hydrophobic interaction. There is an electrostatic interaction between the nitro group of the nitrobenzene substance and the carboxylate group, while the aromatic group of the fluorescent compound and the benzene on the nitrobenzene substance have π-π interaction and hydrophobic-hydrophobic interaction. Fluorescence quenching of fluorescent compounds results from a variety of effects. The trace nitrobenzene substances to be measured are nitrobenzene compounds substituted by electron-donating groups such as aliphatic alkanes, amino groups or halogens. The general formula of the electron-donating group of the detected nitrobenzenes is

Wherein R ₃ , R ₃ ', R ₄ , R ₄ ' and R ₅ are -(CH ₂ )nCH ₃ (n=an integer of 0-10), -NH ₂ , -Cl, -F, -Br or -I electron donating group.

The fluorescent compound provided by the invention is used to detect the application of trace nitrobenzene substances, and the steps are:

(1) Preparation of transmission materials on substrates (glass, quartz, silicon wafers, organic and polymer solid supports, microspheres, nanoparticles or beads, nanofibers and nanotubes, etc.) by pulling, or spin coating and evaporation methods sensitive film.

(2) Test the fluorescence spectrum and photostability of the sensing film.

(3) Take a little nitrobenzene substance at the bottom of the quartz cell, place a ball of absorbent cotton above it to avoid direct contact with the sensing film, seal the quartz cell with a cover, and put it aside for testing.

(4) After placing the sensing film in a closed quartz cell, quickly measure the curve of the fluorescence intensity of the maximum fluorescence emission peak versus time.

The present invention has the following advantages:

(1) The prepared fluorescent compound containing aromatic group and carboxylate structure has high luminous efficiency in solution and solid film, and the synthesis method is simple and the structure is easy to adjust. It is an ideal sensing material for solid-state fluorescent sensing film.

(2) The chemical modification of the sensing compound is strong, and fluorescent sensing materials with different emission wavelengths can be easily obtained by adjusting the type of luminescent group or changing the conjugated structure of the compound.

(3) The effect of the obtained fluorescent compound and nitrobenzene substances is sensitive, and its solid-state fluorescence performance is stable under the presence of no nitrobenzene substances; under the condition that methamphetamine exists, its fluorescence intensity is quenched, according to its fluorescence The change of intensity can realize the detection of p-nitrobenzene substances, and can respond quickly within 10 seconds, and the detection limit can reach 0.1ppm.

Taking Example 2 as an example [Figure 1], the interaction of compound 1 with nitrobenzene saturated vapor was investigated. Under the saturated vapor of nitrobenzene, the intensity of the maximum absorption peak of the sensing membrane was quenched by 37% within 10S.

Taking Example 3 as an example [Fig. 2], the interaction between compound 1 and p-nitrotoluene saturated vapor was investigated. Under the saturated vapor of p-nitrotoluene, the intensity of the maximum absorption peak of the film was quenched by 35% within 10S.

Taking Example 4 as an example [Figure 3], the interaction of Compound 2 with p-nitrotoluene saturated vapor was investigated. Under the saturated vapor of p-nitrotoluene, the intensity of the maximum absorption peak of the film was quenched by 35% within 10S.

Taking Example 5 as an example [Figure 4], the interaction of compound 3 with saturated vapor of o-chloronitrobenzene was investigated. Under the saturated vapor of o-chloronitrobenzene, the intensity of the maximum absorption peak of the film was quenched by 15% within 10S.

Taking Example 6 as an example [Figure 5], the interaction of compound 4 with saturated vapor of o-chloronitrobenzene was investigated. Under the saturated vapor of o-chloronitrobenzene, the intensity of the maximum absorption peak of the film was quenched by 50% within 10S.

Taking Example 7 as an example [Figure 6], the interaction between polymer 5 and p-nitrotoluene saturated vapor was investigated. Under the saturated vapor of p-nitrotoluene, the intensity of the maximum absorption peak of the film was quenched by 50% within 10S.

Taking Example 8 as an example [Fig. 7], the interaction between the polymer 5 and the saturated vapor of o-chloronitrobenzene and p-nitrotoluene was investigated. Under the saturated vapor of o-chloronitrobenzene, the intensity of the maximum absorption peak of the film was quenched by 43% within 10S.

The preparation methods of the above compound 1, compound 2, compound 3, compound 4 and polymer 5 are detailed in Example 1. The synthesis methods of the five compounds or polymers listed are representative and cover the fluorescence of the present invention. General Synthetic Methods of Compounds.

Description of drawings

Fig. 1 is compound 1 self-fluorescence stability (curve a) and the variation (curve b) of fluorescence intensity at the maximum emission wavelength of compound 1 in nitrobenzene vapor;

Fig. 2 is compound 1 self-fluorescence stability (curve a) and the variation (curve b) of fluorescence intensity at the maximum emission wavelength of compound 1 in p-nitrotoluene vapor;

Fig. 3 is compound 2 self-fluorescence stability (curve a) and the variation (curve b) of fluorescence intensity at the maximum emission wavelength of compound 2 in p-nitrotoluene vapor;

Figure 4 is the stability of compound 3 autofluorescence (curve a) and the change of fluorescence intensity at the maximum emission wavelength of compound 3 in o-chloronitrobenzene vapor with time (curve b)

Fig.5 The autofluorescence stability of compound 4 (curve a) and the change of fluorescence intensity at the maximum emission wavelength of compound 4 with time in o-chloronitrobenzene vapor (curve b)

Fig. 6 is polymer 5 self-fluorescent stability (curve a) and the variation (curve b) of fluorescence intensity at the maximum emission wavelength of polymer 5 in p-nitrotoluene vapor;

Fig. 7 The autofluorescent stability of polymer 5 (curve a) and the change of fluorescence intensity at the maximum emission wavelength of polymer 5 with time in o-chloronitrobenzene vapor (curve b).

Detailed ways

The present invention will be further described below in conjunction with the specific embodiments and the accompanying drawings.

Example 1

This example illustrates the preparation methods of Compound 1, Compound 2, Compound 3, Compound 4 and Polymer 5.

(1) Structure and synthesis of compound 1 (n ₁ =1, n ₂ =0, n ₃ =1, R1=-N(Ph) ₃ )

Weigh 0.81g of 4-(diphenylamino)benzaldehyde and dissolve it in 30ml of ethyl acetate, slowly add about 25 equivalents of newly prepared sodium ethoxide solution dropwise, reflux for 24h, and spin the solution to dryness on a rotary evaporator. The obtained crude product was separated by chromatographic column to obtain light yellow solid compound 1.

Mass spectrum (EI): m/z343

Melting point: 65°C

¹ H-NMR (400MHz, CDCl ₃ , 25°C, TMS): δ=7.63-7.60(d, 2H), 7.37(d, 4H), 7.28(m, 8H), 7.13(m, 8H) , 7.07(m, 4H), 7.00(d, 4H).

Elemental Analysis Calcd. for _C23H21NO2 ( _{343.16 )} : C, 80.44; H, 6.16; N, 4.08. Measured values: C, 80.57; H, 6.19; N, 4.02.

(2) Synthesis of Compound 2 (n ₁ =1, n ₂ =0, n ₃ =2, R ₁ =-N(Ph) ₃ )

The preparation method is similar to the synthesis of compound 1.

Mass Spectrum (EI): m/z 441

Melting point: 89°C

Elemental Analysis _Calcd . for _C28H27NO4 ( _441.19 ): C, 76.17; H, 6.16; N, 3.17; Found: C, 78.32; H, 6.23; N, 3.39.

¹ H-NMR (400MHz, DMSO, 25°C, TMS): δ=7.64-7.61(d, 2H), 7.40(d, 4H), 7.33(m, 2H), 7.15(m, 3H), 7.06 (m, 4H), 6.33 (d, 2H), 4.26 (m, 4H), 1.33 (m, 6H).

Elemental Analysis Calcd. for _C23H21NO2 ( _{343.16 )} : C, 80.44; H, 6.16; N, 4.08. Measured values: C, 80.57; H, 6.19; N, 4.02.

(3) Synthesis of Compound 3 (n ₁ =1, n ₂ =0, n ₃ =3, R ₁ =-N(Ph) ₃ )

The preparation method is similar to the synthesis of compound 1.

Mass spectrum (EI): m/z539

Melting point: 90°C

¹ H-NMR (400MHz, DMSO, 25°C, TMS): δ=7.65(s, 3H), 7.45(d, 6H), 7.10(d, 6H), 6.34(d, 3H), 4.26( m, 6H), 1.33 (m, 9H).

Elemental analysis Calcd. for C ₃₃ H ₃₃ NO ₆ (539.23): C73.45, H6.16, N2.10; Measured: C73.40, H6.24, N2.11.

(4) Synthesis of compound 4 (n ₁ =2, n ₂ =1, n ₃ =1 R ₁ =R ₂ =-N(Ph) ₃ )

697.7mg 4-(two 4-bromophenyl) amino) ethyl phenylacrylate) and 1.1g (4-(diphenylamino) phenylboronic acid pinacol ester), 80mg catalyst triphenyl phosphopalladium are dissolved in 15ml Add 0.63ml of 2M potassium carbonate aqueous solution to freshly steamed toluene, reflux and stir the reaction for one day under Ar atmosphere, extract the organic phase and separate it by column chromatography to obtain compound 4 as a yellow solid.

Melting point: 120°C

¹ H-NMR (400MHz, DMSO, 25°C, TMS): δ=7.62(d, 6H), 7.58(m, 5H), 7.31(m, 8H), 7.15(d, 4H), 7.08- 7.01 (m, 16H), 6.98 (m, 2H), 6.47-6.44 (d, 1H), 4.17 (m, 2H), 1.25 (m, 3H).

Mass Spectrum MALDI-TOF m/z 829.4

Elemental Analysis _Calcd . for _C59H47N3O2 ( _{829.37 )} : C85.37, H5.71, N5.06; Measured: C85.68, H5.69, N5.22.

(5) Synthesis of polymer 5 (n ₁ =1, n ₂ =1, n ₃ =1, n=1-1000, R ₁ =-N(Ph) ₃ , )

315mg (4-(di-4-bromophenyl) amino) ethyl phenylacrylate) and 404mg 9,9-dioctylfluorene-2,7-diboronic acid indyl ester, 40mg triphenylphosphopalladium Dissolve in 15ml of toluene, then add 0.3ml of 2M potassium carbonate aqueous solution, reflux and stir for three days under Ar atmosphere, extract the organic phase and drop it into 20ml of anhydrous methanol, and filter the precipitated solid. Dissolved in a small amount of chloroform, then dropped into anhydrous methanol to precipitate, the above operation was repeated several times to obtain polymer 5.

¹ H-NMR (400MHz, DMSO, 25°C, TMS): δ=7.78(m, 2H), 7.68-7.57(m, 2H), 7.29-7.25(m, 3H), 7.17-7.15(m , 3H), 6.35-6.32(s, 1H), 4.29-4.25(m, 2H), 2.04(s, 4H), 1.39-1.36(m, 3H), 1.33-1.25(m, 24H) 0.80-0.73( m, 11H).

Example 2

Sensing films based on compound 1 were prepared on quartz substrates by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a drop of nitrobenzene on the bottom of the quartz pool, pad a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz pool with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in Figure 1, curve a is the autofluorescence characteristic of compound 1, and curve b is the change of fluorescence intensity at the maximum emission wavelength of compound 1 in nitrobenzene vapor with time.

Example 3

Sensing films based on compound 1 were prepared on quartz substrates by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a small amount of p-nitrotoluene at the bottom of the quartz cell, pad a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz cell with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in Figure 2, curve a is the autofluorescence stability of compound 1, and curve b is the change of fluorescence intensity at the maximum emission wavelength of compound 1 in p-nitrotoluene vapor with time.

Example 4

The sensing film based on compound 2 was prepared on the quartz substrate by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a small amount of p-nitrotoluene at the bottom of the quartz cell, place a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz cell with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in Figure 3, curve a is the autofluorescence stability of compound 2, and curve b is the change of fluorescence intensity at the maximum emission wavelength of compound 2 with time in p-nitrotoluene vapor.

Example 5

The sensing film based on compound 3 was prepared on the quartz wafer substrate by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a small amount of o-chloronitrobenzene on the bottom of the quartz pool, pad a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz pool with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in Figure 4, curve a is the autofluorescence stability of compound 3, and curve b is the change of fluorescence intensity at the maximum emission wavelength of compound 3 with time in o-chloronitrobenzene vapor.

Example 6

The sensing film based on compound 4 was prepared on the quartz wafer substrate by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a small amount of o-chloronitrobenzene on the bottom of the quartz pool, pad a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz pool with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in Figure 5, curve a is the autofluorescence stability of compound 4, and curve b is the change of fluorescence intensity at the maximum emission wavelength of compound 4 with time in o-chloronitrobenzene vapor.

Example 7

The sensing film based on polymer 5 was prepared on the quartz wafer substrate by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a small amount of p-nitrotoluene at the bottom of the quartz cell, place a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz cell with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in FIG. 6 , curve a is the autofluorescence stability of polymer 5, and curve b is the change of fluorescence intensity at the maximum emission wavelength of polymer 5 with time in p-nitrotoluene vapor.

Example 8

The sensing film based on polymer 5 was prepared on the quartz wafer substrate by pulling method. Test the fluorescence spectrum and photostability of the sensing film. Put a small amount of o-chloronitrobenzene on the bottom of the quartz pool, pad a ball of absorbent cotton above it to avoid direct contact with the sensing film, and seal the quartz pool with a cover. After placing the sensing film in a closed quartz cell, quickly measure the variation curve of the peak intensity and time at the maximum fluorescence emission peak. As shown in FIG. 7 , curve a is the autofluorescence stability of polymer 5, and curve b is the change of fluorescence intensity at the maximum emission wavelength of polymer 5 with time in o-chloronitrobenzene vapor.

Although the present invention has been described in conjunction with preferred embodiments, the present invention is not limited to the above-mentioned embodiments, and it should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims (1)

1. a class fluorescent chemicals, is characterized in that:

Described fluorescent chemicals is following 4 compounds:

n=1～1000 wherein.