CN115745965A - Fluorescent molecule and preparation method and application thereof - Google Patents

Abstract

The invention provides a fluorescent molecule and a preparation method and application thereof. The invention introduces the propeller-like triphenylamine into the 4-position of 2, 6-bis (oxazol/thiazoyl) pyridine through Sonogashira coupling reaction for the first time. The conjugated length of the tridentate fluorophore is reversely prolonged by constructing a C-C bond, the solid-liquid state fluorescence property of the tridentate fluorophore is improved, and a donor-pi-acceptor (D-pi-A) type fluorescence molecule with a novel structure is synthesized, and the tridentate fluorophore has a proper coordination cavity and obvious intramolecular charge transfer. Test results show that the fluorescent molecule can be used for visually identifying organic solvents with different polarities and rapidly and reliably detecting Cu ²⁺ And Hg ²⁺ The probe is expected to be developed into an organic solvent polar fluorescent probe and a transition metal ion probe.

Description

A kind of fluorescent molecule and its preparation method and application

technical field

The invention belongs to the field of organic synthesis, in particular to a fluorescent molecule and its preparation method and application.

Background technique

Polarity, as one of the most important microenvironmental parameters, plays a crucial role in chemistry and biology. Changes in solvent polarity can seriously affect chemical production, organic synthesis, and material modification, among others. Therefore, it is of great significance to quickly and accurately monitor small changes in polarity. For a long time, the methods or materials of organic solvent polar fluorescent probes reported in the literature and patents mainly include the following:

(1) Mass spectrometry: use liquid chromatography or gas phase mass spectrometry to detect the ion peaks of different organic solvents, and then analyze the polarity changes of the environment according to the characteristic peak changes of the solvents.

(2) Electrochemical method: establish an electrochemical workstation, according to the electrochemical properties of the substances in the solution and their changing laws, through the measurement relationship between electrical quantities such as potential, conductance, current, and electricity, and certain quantities of the measured substances, the group Qualitative analysis is carried out to obtain values such as the polarity change of the microenvironment.

(3) Fluorescence spectroscopy: Many fluorescent probes with polarity sensitivity have been developed for real-time monitoring of solvent polarity changes. The spectral intensities and wavelengths of most fluorescent probes show clear differences with polarity.

Although some of the above analysis methods, such as chromatographic analysis and electrochemical analysis, are developing rapidly, these methods have disadvantages such as high cost, cumbersome detection, and inability to visualize and analyze immediately. Fortunately, solvent-polar fluorescent probes based on fluorescence spectroscopy have begun to attract attention in recent years and have made great progress.

Fluorescence spectroscopy is becoming a promising detection method because of its remarkable advantages such as high selectivity, high sensitivity, good temporal and spatial resolution, non-destructive detection, and easy operation. However, the current polar fluorescent probes still have the disadvantages of single backbone and low polarity sensitivity, and ideal polarity detection tools are still very scarce. Therefore, the development of novel polarity-sensitive probes for visually grasping polarity fluctuations is of great significance for organic reactions and physiological processes.

Organic small-molecule fluorescent probes have the advantages of small size and flexible structure modification, so reliable fluorescence detection methods are highly dependent on small-molecule fluorescent probes. At present, a construction strategy of polarity-sensitive fluorescent probes is to simultaneously introduce electron donor (D) and electron acceptor (A) groups into the molecule. This approach can generate large dipole moments in this structure. The dipole moments of the ground and excited states vary significantly with polarity. In this way, the excited state of the molecule usually undergoes intramolecular charge transfer (ICT), and changes in the polar and nonpolar environment lead to a shift in wavelength or an increase or decrease in intensity in the absorption and emission spectra. For example, Glebov constructed a push-pull system containing cyclopentenone and diarylethene for fluorescence response to different polar solvents. However, the factors affecting polarity are complex and ever-changing, and the detection of polarity in the actual environment is facing severe challenges. In particular, most of the polar fluorescent probes reported so far have shortcomings such as low polarity sensitivity, poor solubility, and difficulty in visual detection. .

According to the previous patent research, the structures of polarity-sensitive probes reported so far are single (only carbazoles and coumarins are involved), and they are aimed at probes with polarity changes in vivo, rather than organic solvent polarity in vitro. Variation of fluorescent probes.

Contents of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned prior art. For this reason, the first aspect of the present invention proposes a kind of fluorescent molecule, based on triphenylamine structure and 2,6-bis-benzimid (oxa/thia) azolylpyridine unit construction, has extensive field in organic solvent polarity sensing It has the advantages of solvent compatibility, high polarity sensitivity, and easy visualization, and it can identify transition metal ions with ultrasensitive visualization in solution and solid state.

The second aspect of the present invention proposes a method for preparing the above-mentioned fluorescent molecules.

A third aspect of the present invention proposes a polar fluorescent probe.

The fourth aspect of the present invention proposes a transition metal ion probe.

The fifth aspect of the present invention proposes a portable detection material.

According to the first aspect of the present invention, a kind of fluorescent molecule is proposed, the structure of described fluorescent molecule is as follows formula (I):

中的一种，R₂＝R₁，R₃为Wherein, R ₁ is selected from

One of them, R ₂ =R ₁ , R ₃ is

In the present invention, the fluorescent molecule is a typical N^N^N tridentate ligand, has a suitable coordination cavity, and is often coordinated with transition metals such as palladium, chromium, iron, zinc, etc., and has metal Ligand-to-ligand charge transfer (MLCT) mechanism, thus exhibiting highly emitted solid-state fluorescence.

In some embodiments of the present invention, the fluorescent molecule is selected from one of the compounds with the following structures:

According to a second aspect of the present invention, a method for preparing the fluorescent molecule described in the first aspect is proposed, comprising:

S1: Using 4-bromopyridine-2,6-dicarboxylic acid, amino group and ortho-substituted benzene as R group as raw materials, under the action of catalyst A, carry out addition cyclization to obtain an intermediate;

S2: The intermediate obtained in S1 and 4-ethynyl-N,N-diphenylaniline are used as raw materials, dissolved in a solvent, and subjected to a coupling reaction under the action of catalyst B with limited oxygen to obtain the fluorescent molecule.

In the present invention, the reaction formula involved in the above-mentioned preparation method is as follows formula (II):

Wherein XH is the R group described in S1.

In the present invention, the fluorophore 2,6-bisbenzimid (oxa/thia)azolylpyridine (formula (III)) involved in the fluorescent molecule is a typical N^N^N tridentate ligand with A suitable coordination cavity is often coordinated with transition metals such as palladium, chromium, iron, and zinc, and has a metal-to-ligand charge transfer (MLCT) mechanism after coordination, thereby showing high-emission solid-state fluorescence. However, the fluorescent molecule synthesized by the present invention is based on the compound of No. 4 R ₄ = Br in formula III as a raw material, and is first passed through the Sonogashira coupling at the No. A joint reaction introduces propeller-shaped triphenylamine. By constructing CC bonds, the conjugation length of tridentate fluorophores is reversely extended, and its solid-liquid fluorescence properties are improved, and a novel donor-π-acceptor (D-π-A) type organic fluorescent molecule is synthesized.

In some embodiments of the present invention, the R group of S1 is selected from any one of mercapto, hydroxyl, and amino.

In some embodiments of the present invention, the amino group of S1 and the ortho-substituted benzene of the R group are selected from any one of o-aminothiophenol, o-aminophenol, and o-phenylenediamine.

In some embodiments of the present invention, the molar ratio of the 4-bromopyridine-2,6-dicarboxylic acid described in S1 to the amino group and the ortho-substituted benzene of the R group is 1: (2-3).

In some embodiments of the present invention, the temperature of the addition cyclization described in S1 is 150°C to 180°C.

In some embodiments of the present invention, the addition cyclization time of S1 is 24h-48h.

In some embodiments of the present invention, the catalyst A in S1 is selected from at least one of polyphosphoric acid (PPA), triphosphoric acid, and pyrophosphoric acid.

In some preferred embodiments of the present invention, after the addition and cyclization described in S1, it further includes: cooling the reaction solution to room temperature, adjusting the pH value to 9-10, separating out solids, and purifying.

In some preferred embodiments of the present invention, the above purification includes: using silica gel column chromatography, using petroleum ether:dichloromethane volume ratio 1:1 as eluent, collecting the effluent, and evaporating the solvent to dryness.

In some embodiments of the present invention, the molar ratio of the intermediate in S2 to 4-ethynyl-N,N-diphenylaniline is 1: (1-3).

In some preferred embodiments of the present invention, the coupling reaction in S2 is a Sonogashira coupling reaction.

In some preferred embodiments of the present invention, the temperature of the coupling reaction in S2 is 80°C-110°C.

In some preferred embodiments of the present invention, the time of the coupling reaction in S2 is 12h-36h.

In some preferred embodiments of the present invention, the coupling reaction in S2 is carried out under basic conditions.

In the present invention, the environment of the coupling reaction is alkaline by adding triethylamine in S2.

In some preferred embodiments of the present invention, the solvent S2 is selected from one of tetrahydrofuran, acetonitrile, and toluene.

In some preferred embodiments of the present invention, the catalyst B described in S2 is a mixture of CuI, Pd(PPh ₃ ) ₂ Cl ₂ and PPh ₃ .

In some preferred embodiments of the present invention, the molar amount of the catalyst B in S2 is 100%-200% of the total molar amount of the intermediate and 4-ethynyl-N,N-diphenylaniline.

In some more preferred embodiments of the present invention, the molar ratio of CuI, Pd(PPh ₃ ) ₂ Cl ₂ and PPh ₃ is 2-2.5: 2-2.5: 1-1.5.

In some more preferred embodiments of the present invention, after the coupling reaction in S2, it further includes: cooling the reaction liquid to room temperature, quenching the reaction with a saturated ammonium chloride solution, and purifying.

In some preferred embodiments of the present invention, the above-mentioned purification includes: using dichloromethane and ammonium chloride aqueous solution to extract, collecting the organic phase, drying, using silica gel column chromatography, using dichloromethane: ethyl acetate volume ratio 10: 1 is the eluent, collect the effluent, and evaporate the solvent to dryness.

According to the third aspect of the present invention, a polar fluorescent probe is proposed, the polar fluorescent probe includes the fluorescent molecule described in the first aspect.

In some embodiments of the present invention, the effective amount of the fluorescent molecule in the polar fluorescent probe is 10 ^-4 mol/L˜10 ^-6 mol/L.

According to a fourth aspect of the present invention, a transition metal ion probe is provided, and the transition metal ion probe includes the fluorescent molecule described in the first aspect.

In some embodiments of the present invention, the transition metal ion is at least one of Cu ²⁺ and Hg ²⁺ .

In some preferred embodiments of the present invention, the effective amount of the fluorescent molecule in the transition metal ion probe is 10 ^-4 mol/L˜10 ^-6 mol/L.

According to a fifth aspect of the present invention, a portable detection material is proposed, the portable detection material includes a paper strip or film loaded with the fluorescent molecules described in the first aspect, and the effective amount of the fluorescent molecules in the portable detection material is 10 ^{- 3} mol/L～10 ^-5 mol/L.

The beneficial effects of the present invention are:

(1) The fluorescent molecule of the present invention is a D-π-A type fluorescent molecule, which has a suitable coordination cavity and significant intramolecular charge transfer (ICT); it has bright and stable solid-liquid state fluorescence emission.

(2) The present invention no longer adopts the method of expensive raw materials and harsh conditions in the prior art to synthesize, but uses cheap and easily available compounds as raw materials, and the reaction is easy to control, the product purification is simple, and the yield is more than 60%.

(3) The fluorescent molecule of the present invention is applied to polar fluorescent probes of organic solvents, which can visually identify organic solvents of different polarities; applied to transition metal ion probes, it can realize ultrasensitive detection of Cu ²⁺ and Hg ²⁺ .

(4) The fluorescent molecules synthesized in the present invention can be further processed into portable detection tools (test strips or thin films), which can be applied to visual recognition of Cu ²⁺ and Hg ²⁺ .

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing and embodiment, wherein:

Fig. 1 is the FT-IR test characterization diagram of fluorescent molecule (4a) obtained in Example 1 of the present invention;

Fig. 2 is the proton nuclear magnetic resonance spectrogram of fluorescent molecule (4a) obtained in Example 1 of the present invention;

Fig. 3 is the carbon nuclear magnetic resonance spectrogram of fluorescent molecule (4a) obtained in Example 1 of the present invention;

Fig. 4 is the mass spectrogram of fluorescent molecule (4a) obtained in Example 1 of the present invention;

Fig. 5 is the fluorescent color and performance test diagram of the fluorescent molecule (4a) obtained in Example 1 of the present invention in different organic solvents;

Fig. 6 is a fluorescent color and performance test diagram of the fluorescent molecule (4b) obtained in Example 2 of the present invention in different organic solvents;

Fig. 7 is a fluorescent color and performance test diagram of the fluorescent molecule (4c) obtained in Example 3 of the present invention in different organic solvents;

Fig. 8 is a test diagram of the selective detection performance of the fluorescent molecule (4a) obtained in Example 1 of the present invention to different metal ions;

Fig. 9 is the test diagram of the detection limit of Cu ²⁺ by the fluorescent molecule (4a) obtained in Example 1 of the present invention;

Fig. 10 is the detection limit test diagram of fluorescent molecule (4a) to Hg ²⁺ obtained in Example 1 of the present invention;

Fig. 11 is the test diagram of the response time of the fluorescent molecule (4a) obtained in Example 1 of the present invention to Cu ²⁺ and Hg ²⁺ ;

Fig. 12 is the visual recognition results of different concentrations of Cu ²⁺ or Hg ²⁺ detected by the test strips and films loaded with fluorescent molecules (4a) obtained in Example 1 of the present invention.

Detailed ways

The conception and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts belong to The protection scope of the present invention.

Example 1

The present embodiment prepares a kind of fluorescent molecule (represented by 4a), the structure is as follows formula (IV):

The specific process is:

Weigh 1mmol of 4-bromopyridine-2,6-dicarboxylic acid and 2.2mmol of o-phenylenediamine, place them in a 50mL round bottom flask, add 10mL of polyphosphoric acid (PPA), raise the reaction temperature to 170°C, and The reaction was performed under magnetic stirring for 36 h. After the reaction, the reaction liquid was cooled to room temperature, and then the pH of the reaction liquid was adjusted to 9-10 with NaOH solution, a gray-green solid was precipitated, and the crude solid was obtained by suction filtration under reduced pressure. Subsequently, petroleum ether and dichloromethane with a volume ratio of 1:1 were selected as the eluent, and the intermediate was obtained by silica gel column chromatography.

Weigh 0.25mmol of intermediate and 0.32mmol of 4-ethynyl-N,N-diphenylaniline as raw materials; (Triphenylphosphine)palladium(II) and 5 mol% triphenylphosphine were used as catalyst; 2 mL of dry triethylamine and 2 mL of dry tetrahydrofuran were weighed as solvent. They were placed in a 25mL Schlenk reaction tube, vacuumed, filled with nitrogen, and refluxed at 110°C for 24h. After the reaction, the reaction solution was cooled to room temperature, and 2 mL of saturated ammonium chloride solution was added to quench the reaction. Subsequently, it was extracted with dichloromethane and ammonium chloride aqueous solution, the organic phase was collected, dried with anhydrous sodium sulfate, and the organic solvent was evaporated under reduced pressure to obtain a solid crude product, and then the volume ratio of dichloromethane to ethyl acetate was 10:1 as the wash The agent was removed, and the pure fluorescent molecule was obtained by silica gel column chromatography separation, with a yield of 60.8%.

The pure fluorescent molecular product obtained above is a yellow solid, and the melting point test result is mp=289.7-290.7°C. FT-IR test and characterization results are shown in Figure 1; FT-IR analysis (KBr, ν, cm ^-1 ) in Figure 1: 3227cm ^-1 , stretching vibration absorption peak of NH on the heterocycle; 3064cm ^-1 , aromatic Stretching vibration absorption peak of unsaturated CH on the ring; 2195cm ^-1 , stretching vibration absorption peak of unsaturated C≡C bond; 1589, 1492, 1446cm ^-1 , stretching vibration absorption peak of aromatic ring skeleton, 1332cm ^-1 , Ar-NR ₂ Bond stretching vibration absorption peak; 1278cm ^-1 , CN bond stretching vibration absorption peak; 891cm ^-1 , benzene ring isolated hydrogen; 828 cm ^-1 , 1,4-disubstituted benzene ring; 741cm ^-1 , benzene ring 1,2- Disubstituted; 697cm ^-1 , 1,3,5-trisubstituted;

The characterization results of ¹ H NMR test are shown in Figure 2; from ^{the 1} H NMR analysis in Figure 2, ¹ H NMR (CDCl ₃ , 600MHz): δ=6.93(d, J=9.0Hz, 2H, ArH), 7.14( d,J=7.2Hz,4H,ArH),7.16-7.19(m,2H,ArH),7.33-7.35(m,4H,ArH),7.38-7.41(m,4H,ArH),7.67(d,J =9.0Hz, 2H, ArH), 7.77(d, J=9.0Hz, 4H, ArH), 8.31(s, 2H, ArH);

^{The 13} C NMR test characterization results are shown in Figure 3; from the ¹³ C NMR analysis of Figure 3, ¹³ C NMR (CDCl ₃ , 150MHz): δ=87.3, 97.6, 114.2, 121.8, 123.6, 126.0, 127.1, 131.4, 134.9, 147.6, 149.7, 150.3, 151.4;

HRMS test characterization results are shown in Figure 4; analyzed by HRMS in Figure 4, m/z (%): Calcd for C ₃₉ H ₂₅ N ₆ ^- ([MH] ^- ):577.2146(100), Found: 577.2144( 100).

It can be seen from the above characterization results that the molecule of the above structural formula (IV) was successfully synthesized in this example.

Example 2

In this embodiment, a fluorescent molecule with a novel structure (represented by 4b) is prepared, and the structure is as follows (V):

The specific process is:

Weigh 1mmol of 4-bromopyridine-2,6-dicarboxylic acid and 2.2mmol of o-aminophenol into a 50mL round bottom flask, add 10mL of polyphosphoric acid (PPA), raise the reaction temperature to 170°C, and The reaction was stirred for 36h. After the reaction, the reaction liquid was cooled to room temperature, and then the pH of the reaction liquid was adjusted to 9-10 with NaOH solution, a gray-green solid was precipitated, and the crude solid was obtained by suction filtration under reduced pressure. Subsequently, the volume ratio of petroleum ether and dichloromethane of 1:1 was selected as the eluent, and the intermediate was obtained by silica gel column chromatography.

Weigh 0.25mmol of intermediate and 0.32mmol of 4-ethynyl-N,N-diphenylaniline as raw materials; (Triphenylphosphine)palladium(II) and 5 mol% triphenylphosphine were used as catalyst; 2 mL of dry triethylamine and 2 mL of dry tetrahydrofuran were weighed as solvent. They were placed in a 25mL Schlenk reaction tube, vacuumed, filled with nitrogen, and refluxed at 110°C for 24h. After the reaction, the reaction solution was cooled to room temperature, and 2 mL of saturated ammonium chloride solution was added to quench the reaction. Subsequently, it was extracted with dichloromethane and ammonium chloride aqueous solution, the organic phase was collected, dried with anhydrous sodium sulfate, and the organic solvent was evaporated under reduced pressure to obtain a solid crude product, and then the volume ratio of dichloromethane to ethyl acetate was 10:1 as the wash The agent was removed, and the pure fluorescent molecule was obtained by silica gel column chromatography with a yield of 72.3%.

The pure fluorescent molecular product obtained above is a yellow solid, and the melting point test result is m.p.=259.4-260.9°C.

Characterized by NMR, IR, and mass spectrometry, the relevant data are as follows:

¹ H NMR(CDCl ₃ ,600MHz):δ=7.04(d,J=8.4Hz,2H,ArH),7.11-7.13(m,2H,ArH),7.16 (d,J=7.8Hz,4H,ArH) ,7.31-7.33(m,4H,ArH),7.42-7.48(m,6H,ArH),7.74(d,J=7.8Hz,2H,ArH),7.88(d,J=7.8Hz,2H,ArH) ,8.57(s,2H,ArH);

¹³ C NMR (CDCl ₃ , 150MHz): δ＝85.3, 97.8, 111.6, 113.4, 120.9, 121.3, 124.2, 125.1, 125.6, 126.4, 126.5, 129.6, 133.3, 134.8, 141.7, 146.8, 149.4, 1601.3;

IR(KBr, ν, cm ^-1 ): 3063cm ^-1 , stretching vibration absorption peak of unsaturated CH on the aromatic ring, 2205cm ^-1 , stretching vibration absorption peak of unsaturated C≡C bond; 1587cm ^-1 , 1545cm ^-1 , 1451cm ^-1 , stretching vibration absorption peak of aromatic ring skeleton; 1364cm ^-1 , tertiary amine, Ar-NR ₂ bond stretching vibration absorption peak; 1250cm ^-1 , CN bond stretching vibration absorption peak; 1065cm ^-1 , CO bond stretching vibration absorption peak ; 828cm ^-1 , two adjacent hydrogens on the benzene ring, 1,4-disubstituted benzene ring; 733cm ^-1 , four adjacent hydrogens on the benzene ring, 1,2-disubstituted benzene ring;

HRMS, m/z (%): Calcd for C ₃₉ H ₂₅ N ₄ O ₂ ⁺ ([M+H] ⁺ ): 581.1972 (100), Found: 581.1961 (100).

Therefore, the molecule of the above structural formula (V) was successfully synthesized in this example.

Example 3

In this embodiment, a fluorescent molecule with a novel structure (represented by 4c) is prepared, and the structure is as follows (VI):

The specific process is:

Weigh 1mmol of 4-bromopyridine-2,6-dicarboxylic acid and 2.2mmol of o-aminothiophenol into a 50mL round bottom flask, add 10mL of polyphosphoric acid (PPA), and raise the reaction temperature to 170°C. Reacted for 36h under magnetic stirring. After the reaction, the reaction liquid was cooled to room temperature, and then the pH of the reaction liquid was adjusted to 9-10 with NaOH solution, a gray-green solid was precipitated, and the crude solid was obtained by suction filtration under reduced pressure. Subsequently, the volume ratio of petroleum ether and dichloromethane of 1:1 was selected as the eluent, and the intermediate was obtained by column chromatography separation.

Weigh 0.25mmol of intermediate and 0.32mmol of 4-ethynyl-N,N-diphenylaniline as raw materials; (Triphenylphosphine)palladium(II) and 5 mol% triphenylphosphine were used as catalyst; 2 mL of dry triethylamine and 2 mL of dry tetrahydrofuran were weighed as solvent. They were placed in a 25mL Schlenk reaction tube, vacuumed, filled with nitrogen, and refluxed at 110°C for 24h. After the reaction, the reaction solution was cooled to room temperature, and 2 mL of saturated ammonium chloride solution was added to quench the reaction. Subsequently, it was extracted with dichloromethane and ammonium chloride aqueous solution, the organic phase was collected, dried with anhydrous sodium sulfate, and the organic solvent was evaporated under reduced pressure to obtain a solid crude product, and then the volume ratio of dichloromethane to ethyl acetate was 10:1 as the wash The agent was removed, and the pure fluorescent molecule was obtained by column chromatography separation method, with a yield of 70.8%.

The pure fluorescent molecular product obtained above is a yellow solid, and the melting point test result is m.p.=290.4-291.6°C.

Characterized by NMR, infrared, mass spectrometry, etc., its structure is correct, and the relevant data are as follows:

¹ H NMR (CDCl ₃ , 600MHz): δ=7.05(d, J=8.4Hz, 2H, ArH), 7.14(t, J=7.2Hz, 2H, ArH), 7.18(d, J=7.2Hz, 4H ,ArH),7.33-7.36(m,4H,ArH),7.45(d,J=9.0Hz,2H,ArH),7.47-7.50(m,2H,ArH),7.55-7.58(m,2H,ArH) ,8.02(d,J=7.8Hz,2H,ArH),8.15(d,J=8.4Hz,2H,ArH), 8.52(s,2H,ArH);

¹³ C NMR (CDCl ₃ , 150MHz): δ＝85.8, 96.8, 113.9, 121.4, 122.1, 123.3, 123.8, 124.1, 125.5, 125.5, 126.5, 129.5, 133.2, 134.5, 136.4, 146.9, 149.1, 154.3 168.2;

IR, (KBr, ν, cm ^-1 ): 3049cm ^-1 , stretching vibration absorption peak of unsaturated CH on the aromatic ring; 2214cm ^-1 , stretching vibration absorption peak of unsaturated C≡C bond; 1586cm ^-1 , 1537cm ^-1 ,1506cm ^-1 , stretching vibration absorption peak of aromatic ring skeleton; 1310cm ^-1 , tertiary amine, Ar-NR ₂ bond stretching vibration absorption peak; 1287cm ^-1 , CN bond stretching vibration absorption peak; 1178cm ^-1 , CS bond stretching vibration absorption peak Peak; 896cm ^-1 , isolated hydrogen on benzene ring; 837cm ^-1 , two adjacent hydrogens on benzene ring, 1,4-disubstituted benzene ring; 756cm ^-1 , three adjacent hydrogens on benzene ring, benzene ring 1, 2-disubstituted; 697cm ^-1 , monosubstituted benzene ring, 1,3,5-trisubstituted;

HRMS, m/z (%): Calcd for C ₃₉ H ₂₅ N ₄ S ₂ ⁺ ([M+H] ⁺ ): 613.1515 (100), Found: 613.1502 (100).

Therefore, the molecule of the above structural formula (VI) was successfully synthesized in this example.

Test case

1. Fluorescent properties of fluorescent molecules of the present invention in different organic solvents

Dissolve the fluorescent molecular products (4a-4c) of Examples 1-3 in 2 mL of 9 different organic solvents (the final concentration of each fluorescent molecular product is ^10-5 mol/L), and the solvents are n-hexane ( Hexane), dichloromethane (DCM), tetrahydrofuran (THF), ethyl acetate (EtOAc), 1,4-dioxane (Dioxane), ethanol (EtOH), acetonitrile (MeCN), N,N-dimethyl dimethylformamide (DMF) and dimethyl sulfoxide (DMSO); under a 365nm desktop ultraviolet lamp, observe respectively the fluorescent colors of the 9 groups (that is, a total of 27 groups) of embodiments 1 to 3 added to the organic solution; use a fluorescence spectrometer , set appropriate parameters, and test the fluorescence emission spectra of each group of organic solutions, and the results are shown in Figure 5, Figure 6, and Figure 7.

From the visualization in Figure 5, it can be found that the fluorescent molecular product of Example 1 (with a concentration of 10 ^-5 mol/L) exhibits distinct purple and green colors in organic solutions of 9 solvents with different polarities (Table 1). , blue, cyan and yellow fluorescent colors. Similarly, it can also be found from the fluorescence emission spectrum ( FIG. 5 ) that its maximum emission peaks in the organic solutions of the above nine kinds of solvents with different polarities are located at different emission wavelengths and have different fluorescence intensities.

From the visualization diagram in Figure 6, it can be found that the fluorescent molecular product of Example 2 (with a concentration of 10 ^-5 mol/L) exhibits distinct purple, green, yellow and red colors in organic solutions of 9 solvents with different polarities and other fluorescent colors. It can also be found from the fluorescence emission spectrum ( FIG. 6 ) that its maximum emission peaks in the organic solutions of the above nine kinds of solvents with different polarities are located at different emission wavelengths and have different fluorescence intensities.

From the visualization in Figure 7, it can be found that the fluorescent molecular product of Example 3 (with a concentration of 10 ^-5 mol/L) exhibits distinct purple and green colors in organic solutions of 9 solvents with different polarities (Table 1). Fluorescent colors such as , yellow and red. It can also be found from the fluorescence emission spectrum (Figure 7) that the maximum emission peaks of 4c (with a concentration of 10 ^-5 mol/L) in the organic solutions of 9 solvents with different polarities are located at different emission wavelengths and have different fluorescence strength.

Therefore, when the fluorescent molecular products of Examples 1-3 are dissolved in organic solvents of different polarities and the concentration is as low as 10 ^{- 5} mol/L, the fluorescence can quickly produce obviously different color responses with small changes in polarity, This shows that it can be used as a polar probe for sensitive and selective visual identification of organic solvents with different polarities.

Table 1 Polarity information table of 9 kinds of organic solvents

2. The selective detection performance of the fluorescent molecules of the present invention to different metal ions

Prepare 19 groups of 2 mL aqueous solutions (10 ^-5 M, H ₂ O/THF, v/v, 80/20) of the fluorescent molecule (4a) obtained in Example 1; add 1 equiv. different types of metal ions (Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Ba ²⁺ , Al ^{3 +} , Cr ³⁺ , Mn ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Ni ²⁺ , Pb ²⁺ , Ag ⁺ , Zn ²⁺ , Cd ²⁺ , Cu ²⁺ , Hg ²⁺ ) for standby; observe the fluorescence of 19 groups of aqueous solutions under a 365nm desktop ultraviolet lamp; select a fluorescence spectrometer, set appropriate parameters, and test 19 groups The results of the fluorescence emission spectrum of the aqueous solution are shown in FIG. 8 , where 4a represents the fluorescent molecule obtained in Example 1.

It can be found from Figure 8 that the aqueous solution of the fluorescent molecule (4a) obtained in Example 1 has strong fluorescence, when Cu ²⁺ is added, the fluorescence of the solution will be strongly quenched, and the addition of Hg ²⁺ will cause the fluorescence of the solution to occur Quenching is red-shifted, but the fluorescence of the solution does not change significantly when other metal ions are added. This shows that the fluorescent molecules obtained in Example 1 can recognize Cu ²⁺ and Hg ²⁺ by naked eyes in aqueous solution.

Similarly, 19 groups of 2mL aqueous solutions (10 ^-5 M, H ₂ O/THF, v/v, 90/10) of the fluorescent molecule (4b) obtained in Example 2 were respectively prepared; 5 equiv .Different types of metal ions (Na ⁺ , K ⁺ , Mg ²⁺ , Ca ²⁺ , Ba ²⁺ , Al ³⁺ , Cr ³⁺ , Mn ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Ni ²⁺ , Pb ²⁺ , Ag ⁺ , Zn ²⁺ , Cd ²⁺ , Cu ²⁺ , Hg ²⁺ ) for standby; observe the fluorescence of 19 groups of aqueous solutions under a 365nm desktop ultraviolet lamp; select a fluorescence spectrometer and set appropriate parameters, The fluorescence emission spectra of 19 groups of aqueous solutions were tested.

The aqueous solution of the fluorescent molecule (4b) obtained in Example 2 has strong fluorescence, and the addition of Hg ²⁺ will cause the quenching red shift of the fluorescence of the solution, while the fluorescence of the solution does not change significantly when other metal ions are added. This shows that the fluorescent molecules obtained in Example 2 can recognize Hg ²⁺ with naked eyes in aqueous solution.

3. The detection limit of fluorescent molecules of the present invention to Cu ²⁺ and Hg ²⁺

Two sets of 2mL aqueous solutions (10 ⁻⁵ M, H ₂ O/THF, v/v, 80/20) of the fluorescent molecule (4a) obtained in Example 1 were respectively prepared; a fluorescence spectrometer was selected, appropriate parameters were set, and the respective tests Group 2 added different concentrations of 0 to 1 equiv. to the fluorescent molecule solution obtained in Example 1 (during the test, the concentration of metal ions was gradually added dropwise to the 4a solution, and the ion concentration gradually increased from 0 to 10 ^-5 mol/ L) Cu ²⁺ or Hg ²⁺ fluorescence emission spectrum, the results are shown in Figure 9 and Figure 10.

From Figure 9, it can be found that when the aqueous solution of the fluorescent molecule (4a) obtained in Example 1 is added dropwise with different concentrations of Cu ²⁺ (0-1 equiv.), the fluorescence of the solution will be gradually quenched with the increase of the concentration of Cu ²⁺ . Further, the fluorescent titration curve was converted into a dot plot of fluorescence intensity and Cu ²⁺ concentration, and the lower detection limit of Cu ²⁺ detected by the fluorescent molecular solution was calculated by the limit of detection formula (LOD=3δ/K) as LOD=1.83×10 ^-11 mol/L.

It can be seen from Figure 10 that when different concentrations of Hg ²⁺ (0-1 equiv.) are added dropwise to the aqueous solution of fluorescent molecules obtained in Example 1, the fluorescence of the solution will gradually quench and red-shift as the concentration of Hg ²⁺ increases. , the fluorescent color changes from green to red. Further, the fluorescent titration curve was transformed into a dot plot of fluorescence intensity and Hg ²⁺ concentration, and the lower limit of detection of Hg ²⁺ detected by the fluorescent molecular solution was calculated by the limit of detection formula (LOD=3δ/K) as LOD=2.12×10 ^-11 mol/L.

4. The detection limit of fluorescent molecules of the present invention to Cu ²⁺ and Hg ²⁺

Two sets of 2mL aqueous solutions (10 ^-5 M, H ₂ O/THF, v/v, 80/20) of the fluorescent molecule (4a) obtained in Example 1 were prepared; the solutions were first added to quartz cuvettes, placed in Then add 1 equivalent of Cu ²⁺ or Hg ²⁺ solution quickly to the fluorescence spectrometer, ^and record the relationship between the maximum fluorescence intensity of the solution and time.

It can be seen from Figure 11 that without any external force, after adding 20 equivalents of Cu ²⁺ or Hg ²⁺ to the aqueous solution of fluorescent molecules obtained in Example 1, the fluorescence intensity of the solution weakens strongly and rapidly, and at 5s Fluorescence diminished to a minimum and no longer changed significantly. This shows that the fluorescent molecules obtained in Example 1 can rapidly detect Cu ²⁺ and Hg ²⁺ .

5. Preparation and visual recognition of portable test strips and films loaded with fluorescent molecules of the present invention

(1) Cut 7 blank filter paper strips of the same size for use; prepare 3 mL of THF solution (10 ^-3 M) of the fluorescent molecule (4a) obtained in Example 1; soak the filter paper strips in the solution for 1 min, take them out and let them dry The preparation of portable test strips was completed immediately after drying; 5 μL of different concentrations (10 ^-3 M, 10 ^-4 M, 10 ^-5 M, 10 ^-6 M, 10 ^-7 M , 10 ^-8 M, 10 ^-9 M) Cu ²⁺ or Hg ²⁺ solution, under a 365nm ultraviolet lamp, the results shown in the first row and the second row of Figure 12 can be observed.

(2) Prepare 5 mL of the dichloromethane solution (10 ^-3 M) of the fluorescent molecule (4a) obtained in Example 1, and weigh 0.5 g of degradable PBAT (polybutylene adipate/butylene terephthalate) Add the above solution and stir overnight at room temperature; spread the polymer solution on a clean glass plate, dry it at 50°C, and cut out 7 film test strips of the same size after cooling; add dropwise to 6 groups of film test strips With 5 μL of Cu ²⁺ or Hg ²⁺ solutions of different concentrations (10 ^-3 M, 10 ^-4 M, 10 ^-5 M), under a 365nm ultraviolet lamp, the results shown in the third row of Figure 12 can be observed.

It can be found from Figure 12 that both the test paper strip and the film loaded with the fluorescent molecule (4a) obtained in Example 1 can exhibit bright blue-green fluorescence, and the filter paper strip and the film were dropped after adding Cu ²⁺ or Hg ²⁺ solution respectively. can be rapidly quenched. This shows that the filter paper strips and films loaded with fluorescent molecules obtained in Example 1 are expected to be applied to the visual identification of Cu ²⁺ and Hg ²⁺ in actual polluted water samples.

The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those of ordinary skill in the art without departing from the gist of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict.

Claims (10)

1. a fluorescent molecule, characterized in that, the structure of the fluorescent molecule is the following formula (I):

Wherein, R ₁ is selected from

One of them, R ₂ =R ₁ , R ₃ is

2. the preparation method of fluorescent molecule described in claim 1 is characterized in that, comprises the steps: S1: Using 4-bromopyridine-2,6-dicarboxylic acid, amino group and ortho-substituted benzene as R group as raw materials, under the action of catalyst A, carry out addition cyclization to obtain an intermediate; S2: The intermediate obtained in S1 and 4-ethynyl-N,N-diphenylaniline are used as raw materials, dissolved in a solvent, and subjected to a coupling reaction under the action of catalyst B with limited oxygen to obtain the fluorescent molecule. 3. The preparation method according to claim 2, characterized in that, the R group described in S1 is selected from any one of mercapto, hydroxyl, and amino; the amino group and R group ortho-substituted benzene are selected from o-aminobenzene Any one of thiophenol, o-aminophenol, and o-phenylenediamine. 4. The preparation method according to claim 2, characterized in that, the molar ratio of 4-bromopyridine-2,6-dicarboxylic acid to amino group and R group ortho-substituted benzene in S1 is 1:(2～3 ). 5. The preparation method according to claim 2, characterized in that the molar ratio of the intermediate in S2 to 4-ethynyl-N,N-diphenylaniline is 1: (1-3). 6. The preparation method according to claim 2, characterized in that the temperature of the addition cyclization in S1 is 150°C-180°C, and the time is 24h-48h. 7. The preparation method according to claim 2, characterized in that the coupling reaction in S2 has a temperature of 80°C-110°C and a time of 12h-36h. 8. A polar fluorescent probe, characterized in that the polar fluorescent probe comprises the fluorescent molecule of claim 1. 9. A transition metal ion probe, characterized in that the transition metal ion probe comprises the fluorescent molecule according to claim 1. 10. A portable detection material, characterized in that, the portable detection material comprises a paper strip or film loaded with the fluorescent molecules according to claim 1, and the effective amount of fluorescent molecules in the portable detection material is 10 ^-3 mol/L ~10 ^-5 mol/L.

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