CN116891494A - Preparation method and application of viscosity-sensitive heterocyclic compounds - Google Patents

Abstract

The invention discloses a preparation method and application of a viscosity-sensitive heterocyclic compound. The structure of the fluorescent dye is as follows: Among them, the substituent R is any one selected from N,N-diphenylamine group and cyano group. The dye is made from a para-substituted product of benzaldehyde and a seven-membered fluoroboron dipyrrole compound as raw materials, and is condensed in one step under the catalytic action of piperidine and acetic acid. The synthesis method is simple, the separation and purification is convenient, and the yield is high. The introduction of aromatic ring substituents increases the conjugation of the molecule, red-shifts the absorption and emission spectra, and can monitor changes in viscosity.

Description

Preparation method and application of viscosity-sensitive heterocyclic compounds

Technical field

The present invention relates to a heterocyclic compound, and more specifically, to a preparation method and application of a viscosity-sensitive heterocyclic compound. This type of compound has a certain response to viscosity. At low viscosity, the fluorescence is weak, and as the viscosity increases, increases, the fluorescence increases.

Background technique

The viscosity of body fluids is an established biomarker of pathological conditions. When cells are subjected to external pressure, abnormal cell viscosity occurs. As a small molecule fluorescent probe that responds to viscosity, BOPYIN probes have the advantages of high sensitivity, small biological light damage, good biocompatibility, and real-time detection. Therefore, they can perform highly sensitive detection of abnormal changes in the intracellular microenvironment. . For example, the increased viscosity exhibited by swelling of mitochondria has been associated with many diseases, such as the neurodegenerative diseases Parkinson's disease, Alzheimer's disease, and atherosclerosis. At the same time, as a probe with a large conjugation system, it has the advantages of low fluorescence background signal and large photon penetration depth. It is of great significance for biological analysis and shows great potential in clinical medical applications.

Fluorescent probes have attracted widespread attention due to their potential convenience and high spatiotemporal resolution for microscopic monitoring of microbial samples. It is very necessary to find small molecule probes for monitoring viscosity for disease diagnosis and basic research. Dyes with rotatable substituents exhibit viscosity-responsive fluorescence enhancement and have large conjugated systems making the probes more penetrating. Usually log (viscosity) is a linear response to log (fluorescence intensity). In a liquid environment with a lower viscosity, the intramolecular rotational bonds of the probe can rotate at a high speed, thus producing a very low background fluorescence signal; while in a liquid environment with a higher viscosity, the molecular rotation is blocked and the molecules emit strong fluorescence signals. . As the viscosity increases, the probe luminescence is enhanced up to 7.5 times.

The probe provided by the invention is a preparation method and application of a viscosity-sensitive heterocyclic compound. Its own fluorescence is weak, but as the viscosity increases, the fluorescence gradually increases. The viscosity sensitivity coefficient is 3.76 to 4.70, and the maximum fluorescence enhancement to viscosity is 2.7 to 7.5 times the original fluorescence intensity.

Contents of the invention

The main purpose of the present invention is to provide a preparation method and application of viscosity-sensitive heterocyclic compounds.

The technical solution of the present invention is as follows:

A preparation method and application of a viscosity-sensitive heterocyclic compound. The chemical structural formula of the compound is:

Among them, the substituent R is any one selected from N,N-diphenylamine group and cyano group. As a preferred embodiment,

The chemical structural formula of the viscosity-sensitive heterocyclic compound is:

any of them.

Synthesize the preparation method and application based on the viscosity-sensitive heterocyclic compound, the method includes the following synthesis path:

The method includes the following steps:

(1) Add compound 1 and toluene to the reaction bottle at room temperature, stir and dissolve, then add compound 2, piperidine, and acetic acid, and heat to reflux to obtain a reaction solution;

(2) The reaction solution in step (1) is rotary evaporated, and then separated by silica gel column chromatography to obtain product I, which is a seven-membered fluoroboron bipyridine derivative.

Compound 1 is a seven-membered fluoroboron dipyrrole compound, and compound 2 is a para derivative of benzaldehyde; the molar ratio of compound 1 to compound 2 is 1:1 to 10. The order of feeding in step (1) is compound 1, toluene, compound 2, piperidine, and acetic acid.

Acetic acid deprotonates the methylene compound to generate a resonance-stable enolate, a carbonyl compound and an iminium ion made from the amine in piperidine. The enol compound and iminium ion generate a tetrahedral intermediate, which is processed by 1 ,2-elimination to obtain the desired α,β-unsaturated dicarbonyl or related compounds. Acetic acid and piperidine both act as activation reactants and need to be added last. The molar feeding ratio of compound 1 to piperidine is 1:1-10, and the molar feeding ratio of compound 1 to acetic acid is 1:1-10.

The heating temperature of step (1) is 30-150°C, and the heating time is 2-18 hours. Depending on the reactants, the reaction temperature and time vary. When the temperature rises above 120°C, the yield decreases; when the temperature drops to 60°C, it will be difficult to start the reaction, resulting in an increase in reaction time.

The application of the seven-membered fluoroboron dipyrrole heterocyclic compound described in the present invention in detecting liquid viscosity.

The liquid is selected from any one or more of DMF, DME, DMSO, ethylene glycol, ethanol, n-butanol, isopropanol, and PBS.

The liquid viscosity range is 0.1-400mPa·s; further preferably 0.1-320mPa·s; further preferably 0.1-300mPa·s; further preferably 0.1-280mPa·s; further preferably 0.1-270mPa·s; further Preferably, it is 0.1-250mPa·s; More preferably, it is 0.1-200mPa·s; Even more preferably, it is 0.1-150mPa·s.

The heterocyclic compounds of the present invention have weak fluorescence under low viscosity conditions due to the energy consumed by the freely rotating non-radiative path. In the case of high viscosity, free rotation is blocked and strong fluorescence is turned on with negligible non-radiative paths. As the viscosity increases, the fluorescence intensity continues to increase. When the viscosity rises to above 400 mpa·s, free rotation is maximized and the fluorescence intensity no longer increases.

The beneficial effects of the present invention are as follows:

(1) The compound of the present invention has a certain response to viscosity. The compound itself has weak fluorescence. As the viscosity increases, the fluorescence gradually increases, and the maximum fluorescence enhancement for viscosity is 7.5 times.

(2) The synthesis reaction conditions of the present invention are easy to control, the product purification is simple, and it has universal applicability.

(3) The synthesis steps of the present invention are simple and the reaction conditions are mild.

Description of the drawings

Figure 1 is a fluorescence spectrum chart of compound I-1 obtained in Example 1 in DMF-glycerol mixtures with different proportions.

Figure 2 is a linear relationship between the fluorescence intensity logI _729nm and logeta of compound I-1 obtained in Example 1.

Figure 3 is a fluorescence spectrum chart of compound I-2 obtained in Example 8 in DMF-glycerol mixtures with different proportions.

Figure 4 is a linear relationship between the fluorescence intensity logI _586nm and logeta of compound I-2 obtained in Example 8.

Detailed ways

The present invention will be further described below with reference to examples, but the scope of protection claimed by the present invention is not limited to the scope expressed in the examples.

Example 1

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (273 mg, 1 mmol) and piperidine (0.09 mL, 1 mmol) in sequence. Acetic acid (0.06 mL, 1 mmol) was heated and stirred at 90°C for 8 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-1 (196.9 mg) with a yield of 30.1%.

Example 2

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (546 mg, 1 mmol) and piperidine (0.09 mL, 1 mmol) in sequence. Acetic acid (0.06 mL, 1 mmol) was heated and stirred at 90°C for 8 hours to complete the reaction. The reactant was rotary evaporated and purified by column chromatography to obtain purple solid I-1 (306.1 mg) with a yield of 46.8%. When the amount of 4-cyanobenzaldehyde was doubled relative to Example 1, the yield increased by 16.7%.

Example 3

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (273 mg, 1 mmol) and piperidine (0.18 mL, 2 mmol) in sequence. Acetic acid (0.12 mL, 2 mmol) was heated and stirred at 90°C for 8 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-1 (175.9 mg) with a yield of 26.9%. When the amounts of piperidine and acetic acid were doubled compared to Example 1, the yield did not change significantly.

Example 4

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (273 mg, 1 mmol) and piperidine (0.09 mL, 1 mmol) in sequence. Acetic acid (0.06 mL, 1 mmol) was heated and stirred at 120°C for 6 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-1 (428.4 mg) with a yield of 65.5%. When the reaction temperature was increased by 30°C compared to Example 1, the reaction time was reduced by 2 hours, and the yield increased by 35.4%.

Example 5

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (273 mg, 1 mmol) and piperidine (0.09 mL, 1 mmol) in sequence. Acetic acid (0.06 mL, 1 mmol) was heated and stirred at 140°C for 6 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-1 (106.6 mg) with a yield of 16.3%. When the reaction temperature was increased by 50°C compared to Example 1, the reaction time was reduced by 2 hours, and the yield was reduced by 13.8%.

Example 6

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (273 mg, 1 mmol) and piperidine (0.09 mL, 1 mmol) in sequence. Acetic acid (0.06 mL, 1 mmol) was heated and stirred at 60°C for 12 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-1 (123.6 mg) with a yield of 18.9%. When the reaction temperature was reduced by 30°C compared to Example 1, the reaction time was increased by 4 hours, and the yield was reduced by 11.2%.

Example 7

Weigh Compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 60.00 mL of toluene, and then add 4-diphenylaminobenzaldehyde (273 mg, 1 mmol) and piperidine (0.09 mL, 1 mmol) in sequence. Acetic acid (0.06 mL, 1 mmol) was heated and stirred at 90°C for 8 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-1 (179.2 mg) with a yield of 27.4%. When the volume of toluene was doubled relative to Example 1, the yield decreased by 2.7%.

Example 8

Weigh compound 1 seven-membered fluoroboron dipyrrole compound (399 mg, 1 mmol), mix and dissolve 30 mL of toluene, then add 4-cyanobenzaldehyde (131 mg, 1 mmol), piperidine (0.09 mL, 1 mmol), acetic acid ( 0.06 mL, 1 mmol) was heated and stirred at 90°C for 8 hours to complete the reaction. The reactant was evaporated and purified by column chromatography to obtain purple solid I-2 (228.2 mg) with a yield of 34.9%.

Example 9 - Response of Compounds I-1, I-2 to Viscosity

Weigh Compound I-1 (6.54 mg, 0.01 mmol), dissolve 1 mL of DMF to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of DMF and glycerol of different viscosities to prepare a 33.3 μmol /L of the solution to be tested, where (DMF: glycerin = 10:0, such as 3ml of DMF, the viscosity is 0.77mPa·s), (DMF: glycerol = 9:1, such as the compound of 2.7ml DMF and 0.3ml glycerol, the viscosity is 1.5mPa·s), (DMF:glycerol=8:2, such as the compound of 2.4ml DMF and 0.6ml glycerin, the viscosity is 2.41mPa·s), (DMF:glycerin=7:3, such as 2.1ml DMF and 0.9 The compound of ml glycerol has a viscosity of 4.22mPa·s), (DMF:glycerol=6:4, such as the compound of 1.8ml DMF and 1.2ml glycerol, the viscosity is 7.36mPa·s) (DMF:glycerin=5:5, such as The compound of 1.5ml DMF and 1.5ml glycerol has a viscosity of 14.2mPa·s), (DMF:glycerol=4:6, such as the compound of 1.2ml DMF and 1.8ml glycerol, the viscosity is 19.9mPa·s), (DMF:glycerol=4:6) =3:7, such as the compound of 0.9ml DMF and 2.1ml glycerol, viscosity is 64.6mPa·s), respectively detect their fluorescence spectra, get Figure 1, and fit the linear relationship between the fluorescence intensity logI _729nm and logeta, get Figure 2 . The fluorescence of I-1 itself is weak, but as the viscosity increases, the fluorescence gradually increases. The viscosity coefficient is 4.7, and the maximum fluorescence enhancement over viscosity is 2.7 times.

Weigh Compound I-1 (6.54 mg, 0.01 mmol), dissolve 1 mL of DME to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of DME and glycerin of different viscosities to prepare a 33.3 μmol /L of the solution to be tested, among which (DME:glycerol=10:0), (DME:glycerin=9:1), (DME:glycerol=8:2), (DME:glycerin=7:3), (DME: Glycerol=6:4) (DME:glycerol=5:5), (DME:glycerin=4:6), their fluorescence spectra were detected respectively. As the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-260mPa·s.

Weigh Compound I-1 (6.54 mg, 0.01 mmol) and dissolve 1 mL of DMSO to prepare a 0.01 mol/L mother solution. Then take 10 μL of each mother solution and dissolve it into 3 ml of a mixture of DMSO and glycerin of different viscosities to prepare 33.3 μmol. /L of the solution to be tested, among which (DMSO:glycerol=10:0), (DMSO:glycerin=9:1), (DMSO:glycerin=8:2), (DMSO:glycerol=7:3), (DMSO: Glycerin=6:4) (DMSO:glycerin=5:5), (DMSO:glycerin=4:6), (DMSO:glycerin=3:7), (DMSO:glycerol=2:8), (DMSO:glycerol=2:8) =1:9) Their fluorescence spectra were detected respectively. As the viscosity increased, the fluorescence gradually increased. The detectable viscosity range is 0.1-300mPa·s.

Weigh Compound I-1 (6.54 mg, 0.01 mmol), dissolve 1 mL of ethylene glycol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of the mother solution into 3 ml of a mixture of ethylene glycol and glycerin of different viscosities. Prepare a test solution of 33.3 μmol/L, including (ethylene glycol: glycerin = 10: 0), (ethylene glycol: glycerol = 9: 1), (ethylene glycol: glycerol = 8: 2), (ethylene glycol: glycerol = 8: 2), Alcohol: glycerin = 7: 3), (ethylene glycol: glycerin = 6: 4), (ethylene glycol: glycerol = 5: 5), (ethylene glycol: glycerin = 4: 6), (ethylene glycol: Glycerol = 3:7) and (ethylene glycol: glycerol = 2:8) respectively detect their fluorescence spectra. As the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-270mPa·s.

Weigh Compound I-1 (6.54 mg, 0.01 mmol), dissolve 1 mL of ethanol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of ethanol and glycerol of different viscosities to prepare 33.3 μmol. /L of the solution to be tested, among which (ethanol: glycerol = 10:0), (ethanol: glycerol = 9:1), (ethanol: glycerol = 8:2), (ethanol: glycerol = 7:3), (ethanol: Glycerol=6:4), (ethanol:glycerol=5:5), (ethanol:glycerin=4:6), (ethanol:glycerol=3:7) respectively detect their fluorescence spectra. As the viscosity increases, the fluorescence Gradually increase. The detectable viscosity range is 0.1-200mPa·s.

Weigh Compound I-1 (6.54 mg, 0.01 mmol), dissolve 1 mL of n-butanol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of n-butanol and glycerin of different viscosities. Prepare a test solution of 33.3 μmol/L, among which (n-butanol: glycerin = 10:0), (n-butanol: glycerin = 9:1), (n-butanol: glycerol = 8:2), (n-butanol: glycerol = 8:2) Alcohol: glycerol = 7: 3), (n-butanol: glycerol = 6: 4), (n-butanol: glycerol = 5: 5), (n-butanol: glycerol = 4: 6), respectively detect their fluorescence spectra. , as the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-200mPa·s.

Weigh Compound I-1 (6.54 mg, 0.01 mmol), dissolve 1 mL of isopropyl alcohol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of isopropyl alcohol and glycerin of different viscosities. Prepare a test solution of 33.3 μmol/L, among which (isopropyl alcohol: glycerol = 10: 0), (isopropyl alcohol: glycerol = 9: 1), (isopropyl alcohol: glycerol = 8: 2), (isopropyl alcohol: glycerol = 8: 2), Alcohol: glycerol = 7: 3), (isopropyl alcohol: glycerin = 6: 4), (isopropyl alcohol: glycerin = 5: 5), (isopropyl alcohol: glycerin = 4: 6), (isopropyl alcohol: Glycerol = 3:7) and (isopropyl alcohol: glycerol = 2:8) respectively detected their fluorescence spectra. As the viscosity increased, the fluorescence gradually increased. The detectable viscosity range is 0.1-250mPa·s.

Weigh Compound I-1 (6.54 mg, 0.01 mmol) and dissolve 1 mL of PBS to prepare a 0.01 mol/L mother solution. Then, take 10 μL of each mother solution and dissolve it into 3 ml of a mixture of PBS and glycerol of different viscosities to prepare a 33.3 μmol/L solution. L of the solution to be tested is (PBS:glycerol=10:0), (PBS:glycerol=9:1), (PBS:glycerol=8:2), (PBS:glycerol=7:3), (PBS:glycerol=7:3) =6:4), (PBS:glycerol=5:5), (PBS:glycerol=4:6), (PBS:glycerol=3:7), (PBS:glycerol=2:8) respectively detect their fluorescence Spectrum, as the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-250mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve it in 1 mL of DMF to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of DMF and glycerol of different viscosities to prepare a 33.3 μmol /L of the solution to be tested, where (DMF: glycerin = 10:0, such as 3ml of DMF, the viscosity is 0.77mPa·s), (DMF: glycerol = 9:1, such as the compound of 2.7ml DMF and 0.3ml glycerol, the viscosity is 1.5mPa·s), (DMF:glycerol=8:2, such as the compound of 2.4ml DMF and 0.6ml glycerin, the viscosity is 2.41mPa·s), (DMF:glycerin=7:3, such as 2.1ml DMF and 0.9 The compound of ml glycerol has a viscosity of 4.22mPa·s), (DMF:glycerol=6:4, such as the compound of 1.8ml DMF and 1.2ml glycerol, the viscosity is 7.36mPa·s) (DMF:glycerin=5:5, such as Compounds of 1.5ml DMF and 1.5ml glycerol, with a viscosity of 14.2mPa·s) were used to detect their fluorescence spectra, and Figure 3 was obtained, and the linear relationship between the fluorescence intensity logI _586nm and logeta was fitted to obtain Figure 4. The fluorescence of I-2 itself is weak, but as the viscosity increases, the fluorescence gradually increases. The viscosity coefficient is 3.76, and the maximum fluorescence enhancement over viscosity is 7.5 times.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve 1 mL of DME to prepare a 0.01 mol/L mother solution, and then take 10 μL of each mother solution and dissolve it into 3 ml of a mixture of DME and glycerin with different viscosities to prepare 33.3 μmol. /L of the solution to be tested, among which (DME:glycerol=10:0), (DME:glycerin=9:1), (DME:glycerol=8:2), (DME:glycerin=7:3), (DME: Glycerol=6:4) (DME:glycerol=5:5), (DME:glycerol=4:6), (DME:glycerol=3:7), (DME:glycerol=2:8) detect their fluorescence respectively Spectrum, as the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-320mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve 1 mL of DMSO to prepare a 0.01 mol/L mother solution, and then take 10 μL of each mother solution and dissolve it into 3 ml of a mixture of DMSO and glycerol of different viscosities to prepare 33.3 μmol. /L of the solution to be tested, among which (DMSO:glycerol=10:0), (DMSO:glycerin=9:1), (DMSO:glycerin=8:2), (DMSO:glycerol=7:3), (DMSO: Glycerol=6:4) (DMSO:glycerol=5:5), (DMSO:glycerol=4:6), (DMSO:glycerol=3:7), DMSO:glycerol=2:8) respectively detect their fluorescence spectra , as the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-280mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve 1 mL of ethylene glycol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of ethylene glycol and glycerol of different viscosities. Prepare a test solution of 33.3 μmol/L, including (ethylene glycol: glycerin = 10: 0), (ethylene glycol: glycerol = 9: 1), (ethylene glycol: glycerol = 8: 2), (ethylene glycol: glycerol = 8: 2), Alcohol: glycerin = 7: 3), (ethylene glycol: glycerin = 6: 4), (ethylene glycol: glycerol = 5: 5), (ethylene glycol: glycerin = 4: 6), (ethylene glycol: Glycerin = 3:7), (ethylene glycol: glycerol = 2:8), (ethylene glycol: glycerin = 1:9) respectively detect their fluorescence spectra. As the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-300mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve 1 mL of ethanol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of ethanol and glycerol of different viscosities to prepare 33.3 μmol. /L of the solution to be tested, among which (ethanol: glycerol = 10:0), (ethanol: glycerol = 9:1), (ethanol: glycerol = 8:2), (ethanol: glycerol = 7:3), (ethanol: Glycerol=6:4), (ethanol:glycerin=5:5), (ethanol:glycerin=4:6) respectively detect their fluorescence spectra. As the viscosity increases, the fluorescence gradually increases. The detectable viscosity range is 0.1-230mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve 1 mL of n-butanol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of n-butanol and glycerin of different viscosities. Prepare a test solution of 33.3 μmol/L, among which (n-butanol: glycerin = 10:0), (n-butanol: glycerin = 9:1), (n-butanol: glycerol = 8:2), (n-butanol: glycerol = 8:2) Alcohol: glycerin = 7: 3), (n-butanol: glycerin = 6: 4), (n-butanol: glycerol = 5: 5), (n-butanol: glycerol = 4: 6), (n-butanol: Glycerin = 3:7) Their fluorescence spectra were detected respectively. As the viscosity increased, the fluorescence gradually increased. The detectable viscosity range is 0.1-180mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol), dissolve 1 mL of isopropyl alcohol to prepare a 0.01 mol/L mother solution, and then dissolve 10 μL of each mother solution into 3 ml of a mixture of isopropyl alcohol and glycerin of different viscosities. Prepare a test solution of 33.3 μmol/L, among which (isopropyl alcohol: glycerol = 10: 0), (isopropyl alcohol: glycerol = 9: 1), (isopropyl alcohol: glycerol = 8: 2), (isopropyl alcohol: glycerol = 8: 2), Alcohol: glycerol = 7: 3), (isopropyl alcohol: glycerin = 6: 4), (isopropyl alcohol: glycerin = 5: 5), (isopropyl alcohol: glycerin = 4: 6), (isopropyl alcohol: Glycerol = 3:7) and (isopropyl alcohol: glycerol = 2:8) respectively detected their fluorescence spectra. As the viscosity increased, the fluorescence gradually increased. The detectable viscosity range is 0.1-250mPa·s.

Weigh Compound I-2 (5.12 mg, 0.01 mmol) and dissolve 1 mL of PBS to prepare a 0.01 mol/L mother solution. Then take 10 μL of each mother solution and dissolve it into 3 ml of a mixture of PBS and glycerol of different viscosities to prepare a 33.3 μmol/L solution. L of the solution to be tested is (PBS:glycerol=10:0), (PBS:glycerol=9:1), (PBS:glycerol=8:2), (PBS:glycerol=7:3), (PBS:glycerol=7:3) =6:4), (PBS:glycerol=5:5), their fluorescence spectra were detected respectively, and as the viscosity increased, the fluorescence gradually increased. The detectable viscosity range is 0.1-150mPa·s.

The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments in the present application can be arbitrarily combined with each other as long as there is no conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of the present invention.

Claims (6)

1. A seven-membered fluoroboron dipyrrole heterocyclic compound, characterized in that the structural formula of the heterocyclic compound is: Among them, the substituent R is any one selected from N,N-diphenylamine group and cyano group. 2. The preparation method of a kind of seven-membered fluoroboron dipyrrole heterocyclic compound according to claim 1, characterized in that the method includes the following synthesis path: Wherein, the substituent R is any one selected from N,N-diphenylamine group and cyano group, (1) Add compound 1 and toluene to the reaction bottle at room temperature, stir and dissolve, then add compound 2, piperidine, and acetic acid, and heat to reflux to obtain a reaction solution; (2) The reaction solution in step (1) is rotary evaporated, and then separated by silica gel column chromatography to obtain product I, which is a seven-membered fluoroboron dipyrrole heterocyclic compound. 3. The method according to claim 2, characterized in that, in the step (1), compound 2 is a para derivative of benzaldehyde, and the molar ratio of compound 1 to the para derivative of benzaldehyde is 1:1～10. 4. The method according to claim 2, characterized in that the heating temperature of step (1) is 30-150°C, and the heating time is 2-18 hours. 5. Application of a seven-membered fluoroboron dipyrrole heterocyclic compound in detecting liquid viscosity according to claim 1. 6. Application according to claim 5, characterized in that the liquid is selected from any one or more of DMF, DME, DMSO, ethylene glycol, ethanol, n-butanol, isopropanol, and PBS. .