Preparation Method and Application of a Conjugated Organic Small Molecule Containing BODIPY Structure

Abstract

The present invention belongs to the field of electrochemical gas sensing technology, and specifically relates to a preparation method and application of a conjugated organic small molecule based on a BODIPY structure. The present invention uses a BODIPY molecule containing fluoroboron dipyrrole as an ammonia response unit, develops a class of conjugated organic small molecules containing a BODIPY structure by regulating reaction monomers, and achieves high response, high selectivity, fast response and recovery time in ammonia sensing. Therefore, it can be used as a recyclable ammonia sensor to effectively detect ammonia molecules. The conjugated organic small molecule containing a BODIPY structure is obtained by reacting a conjugated structural monomer with an aldehyde group, a pyrrole monomer, and boron trifluoride diethyl ether, and the relevant organic conjugated small molecule material is obtained through purification. As a new type of sensing material with extremely high ammonia response, selectivity and recoverability, there are few reports in the field of electrochemical gas sensing technology.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochemical gas sensing, and in particular, to a preparation method and application of a conjugated organic small molecule containing a BODIPY structure. Background Art

[0002] With the rapid development of modern industry, the detection of toxic and harmful gases is particularly necessary for environmental safety and human health. It is crucial to develop high-efficiency, stable, highly sensitive, and selective ppm-level gas sensors. Based on this, gas sensors have received extensive attention from scientific researchers in recent years. The rapid development of gas sensing technology is closely related to the development of new and efficient gas-sensitive materials.

[0003] Currently, semiconductor-based gas-sensitive materials are designed and developed as the main sensing materials. In particular, metal semiconductor gas-sensitive materials represented by zinc oxide thin films and non-metal organic semiconductor materials represented by polythiophene, dialkyltetrathiafulvalene, polypyrrole, etc. have been widely studied. Although great progress has been made, current semiconductor sensors still have disadvantages such as baseline drift, high power consumption, limited response and selectivity. Therefore, it is necessary to develop new gas-sensitive materials to meet the requirements of gas detection.

[0004] Fluoroboron dipyrrole compounds (abbreviated as BODIPY) are one of the very excellent emerging organic structures. The two pyrrole rings on the left and right of its parent structure are connected by a methine bridge bond, and there is a boron-nitrogen six-membered heterocyclic ring in the middle. The three rings form a very good rigid conjugated planar structure, and the two fluorine atoms connected to the boron atom are located at both ends of the BODIPY core plane. Therefore, fluoroboron dipyrrole (BODIPY) has unique optoelectronic properties and has been widely used in the fields of organic solar cells, optical information storage, self-assembled materials, and photodynamic therapy. In addition, BODIPY with intermolecular hydrogen bonds has also received extensive attention in the field of detection technology. Summary of the Invention

[0005] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a BODIPY molecule containing fluoroboron dipyrrole as an ammonia response unit. By regulating reaction monomers, a class of conjugated organic small molecules containing a BODIPY structure is developed, and high response, high selectivity, fast response and recovery time in ammonia sensing are achieved. Therefore, it can be used as a recyclable ammonia sensor to effectively detect ammonia molecules.

[0006] The conjugated organic small molecule containing a BODIPY structure is obtained by reacting an aldehyde-group conjugated structural monomer, a pyrrole monomer, and boron trifluoride diethyl ether. After purification, the relevant organic conjugated small molecule material is obtained. As a new sensing material with extremely high ammonia response, selectivity, and recovery, there are few reports in the technical field of electrochemical gas sensing.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a conjugated organic small molecule containing a BODIPY structure, and the structural formula of the conjugated organic small molecule containing a BODIPY structure is shown as the following formula (1) or formula (Ⅱ):

[0009]

[0010] Wherein, the is selected from any one of the following structures:

[0011]

[0012] Wherein, R1 is selected from any one of H, O, an alkyl chain, an alkylthio chain, an alkoxy chain, a cyano group, a halogen atom, a carboxyl group, an aldehyde group, a hydroxyl group, and a nitro substituent with C1 to C 40 alkyl, and R2 is selected from any one of C, N, S, Se, and Te;

[0013] It is obtained by reacting an aldehyde group-containing monomer, a pyrrole monomer, and boron trifluoride diethyl ether. The structural formula of the aldehyde group-containing monomer is

[0014] Preferably, the specific steps are as follows: Under anhydrous and anaerobic conditions, the aldehyde group-containing monomer, the pyrrole monomer, and TFA are reacted under heating and reflux for 12 hours. After the product is treated, DDQ is added. One hour later, boron trifluoride diethyl ether and triethylamine are added, and the reaction continues under heating and reflux for 4 hours. After the reaction is completed, the product is purified to obtain a conjugated organic small molecule containing a BODIPY structure.

[0015] Preferably, the molar ratio of the aldehyde group-containing monomer: pyrrole monomer: DDQ: boron trifluoride diethyl ether: triethylamine is 1:6:1:16:8.

[0016] Preferably, the reaction temperature of the reaction is 45-55°C.

[0017] Preferably, the solvent used under anhydrous conditions is anhydrous dichloromethane.

[0018] In addition, the present application also provides an application of a conjugated organic small molecule containing a BODIPY structure prepared by the above method in a gas-sensitive material of a gas sensor.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. The present invention innovatively designs a class of conjugated organic small molecules containing BODIPY structure. Using them as sensing materials, gas sensors with excellent performance are obtained, showing high response, selectivity and stability to ammonia, and realizing the potential application of conjugated organic small molecule sensing materials containing BODIPY structure in the field of gas sensing;

[0021] 2. The conjugated organic small molecule material containing BODIPY structure based on the present invention has the advantages of simple and green reaction routes, and can be applied in actual production. Brief Description of the Drawings

[0022] Figure 1 Response and recovery diagram of the conjugated organic small molecule 3 prepared in Example 1 after being treated with 20 ppm ammonia.

[0023] Figure 2 Response and recovery diagram of 5 cycles of the conjugated organic small molecule 3 prepared in Example 1 after being treated with 20 ppm ammonia.

[0024] Figure 3 Fast response and recovery diagram of the conjugated organic small molecule 3 prepared in Example 1 after being treated with ammonia at different concentrations.

[0025] Figure 4 Response of the conjugated organic small molecule 3 prepared in Example 1 to other 6 gases (all at a concentration of 20 ppm).

[0026] Figure 5 Current-voltage characteristic diagram of the conjugated organic small molecule 3 prepared in Example 1 before and after being treated with 20 ppm ammonia.

[0027] Figure 6 1H NMR spectrum of the organic small molecule 3 prepared in Example 1.

[0028] Figure 7 1H NMR spectrum of the organic small molecule 5 prepared in Example 2.

[0029] Figure 8 1H NMR spectrum of the organic small molecule 7 prepared in Example 3. Detailed Embodiments

[0030] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those of ordinary skill in the art without creative efforts shall all fall within the scope of protection of this application.

[0031] Example 1:

[0032] Preparation of an organic small molecule containing a BODIPY structure. The chemical reaction process is as follows:

[0033]

[0034] Compound 1, Compound 2, TFA, DDQ, boron trifluoride diethyl etherate, triethylamine, and dichloromethane were purchased from companies such as Macklin and Aladdin. Among them, dichloromethane was used after anhydrous treatment.

[0035] Preparation of Compound 3:

[0036] React Compound 1 and Compound 2. Specifically: Take Compound 1, namely trans-4-formyldiphenylethylene (200.4 mg, 0.963 mmol), and Compound 2, namely 2,4-dimethyl-3-ethylpyrrole (355.9 mg, 2.889 mmol), as starting materials, and place them in a two-necked flask under argon protection. Then, pass argon to evacuate and replace the gas in the system multiple times until an anaerobic condition is reached. Add dry dichloromethane (8 mL) and two drops of TFA. Keep the system anhydrous and anaerobic. After refluxing and stirring at 50 °C for 12 h, take it out for purification. Dissolve the product in dichloromethane (8 mL), continue to add DDQ (218.6 mg, 0.963 mmol) and react for 1 hour, then add boron trifluoride diethyl etherate (522.3 mg, 7.704 mmol) and triethylamine (389.5 mg, 3.852 mmol). Add half of each first and then add the other half after 1 hour to make the reaction in the system complete. After refluxing and stirring at 50 °C for 4 h, stop the reaction and perform extraction. After removing the solvent under reduced pressure, a dark brown oily liquid is obtained, which is purified by silica gel column chromatography (dichloromethane / n-hexane = 2:1) to obtain Compound 3 (106 mg) with a yield of 23%.

[0037] Perform component analysis on the obtained Compound 3, as Figure 6 shown, 1 H NMR (400 MHz, CDCl3, 25 °C) δ 7.65 (d, J = 5.6 Hz, 2H), 7.56 (d, J = 4.8 Hz, 2H), 7.40–7.37 (m, 2H), 7.31–7.27 (m, 3H), 7.24–7.16 (m, 2H), 2.54 (s, 6H), 2.33–2.29 (m, 4H), 1.36 (s, 6H), 1.00–0.98 (m, 6H).

[0038] Example 2

[0039]

[0040] Compound 4, Compound 2, TFA, DDQ, boron trifluoride diethyl etherate, triethylamine, and dichloromethane were purchased from companies such as Macklin and Aladdin. Among them, dichloromethane was used after anhydrous treatment.

[0041] Preparation of Compound 5:

[0042] React Compound 4 and Compound 2. Specifically, take Compound 4, namely 2,3,5,6-tetrafluorobenzaldehyde (200.5 mg, 0.973 mmol), and Compound 2, namely 2,4-dimethyl-3-ethylpyrrole (719.5 mg, 5.839 mmol), as starting materials, and place them in a two-necked flask under argon protection. Then, pass argon to purge and replace the system with gas multiple times until an anaerobic condition is reached. Add dry dichloromethane (8 mL) and two drops of TFA. Keep the system anhydrous and anaerobic. After refluxing and stirring at 45 °C for 12 h, take it out for purification. Dissolve the product in dichloromethane (8 mL), continue to add DDQ (220.8 mg, 0.973 mmol) and react for 1 hour. Then add boron trifluoride diethyl etherate (1055.8 mg, 15.537 mmol) and triethylamine (787.3 mg, 7.786 mmol). Add half of them first and then the other half after 1 hour to complete the reaction of the system. After refluxing and stirring at 45 °C for 4 h, stop the reaction and perform extraction. After removing the solvent under reduced pressure, a dark brown oily liquid is obtained. Purify it by silica gel column chromatography (dichloromethane / n-hexane = 2:1) to obtain Compound 5 (146 mg) with a yield of 20%.

[0043] Perform component analysis on the obtained Compound 5, as Figure 7 shown, 1 H NMR (400 MHz, CDCl3, 25 °C) δ 2.56 (s, 6H), 2.38–2.32 (m, 4H), 1.37–1.33 (m, 6H), 1.05–1.02 (m, 6H).

[0044] Example 3

[0045]

[0046] Compound 6, Compound 2, TFA, DDQ, boron trifluoride diethyl etherate, triethylamine, and dichloromethane were purchased from companies such as Macklin and Aladdin. Among them, dichloromethane was used after anhydrous treatment.

[0047] Preparation of Compound 7:

[0048] Compound 6 and Compound 2 were reacted as follows: Take Compound 6, namely 4,4'-biphenyldicarboxaldehyde (199.8 mg, 0.951 mmol), and Compound 2, namely 2,4-dimethyl-3-ethylpyrrole (702.6 mg, 5.703 mmol), as starting materials, and place them in a two-necked flask under argon protection. Then, pass argon to evacuate and replace the gas in the system multiple times until an anaerobic condition is reached. Add dry dichloromethane (8 mL) and two drops of TFA. Keep the system anhydrous and anaerobic. After refluxing and stirring at 55 °C for 12 h, take it out for purification. Dissolve the product in dichloromethane (8 mL), and continue to add DDQ (215.8 mg, 0.951 mmol) and react for 1 hour. Then add boron trifluoride diethyl ether (1031.1 mg, 15.208 mmol) and triethylamine (768.9 mg, 7.604 mmol). Add half of them first, and then add the other half after 1 hour to complete the reaction of the system. After refluxing and stirring at 55 °C for 4 h, stop the reaction and perform extraction. After removing the solvent under reduced pressure, a dark brown oily liquid is obtained. Purify it by silica gel column chromatography (dichloromethane / n-hexane = 2:1) to obtain Compound 7 (151 mg) with a yield of 21%.

[0049] Perform elemental analysis on the obtained Compound 7, as Figure 8 shown 1 H NMR (400 MHz, CDCl3, 25 °C) δ 7.82 (d, J = 8.0 Hz, 4H), 7.42 (d, J = 7.6 Hz, 4H), 2.55 (s, 12H), 2.33–2.31 (m, 8H), 1.43–1.39 (m, 12H), 1.02–0.98 (m, 12H). Example 4

[0050] Taking the material obtained in Example 1 (Compound 3) as an example, illustrate the application of the conjugated organic small molecule containing BODIPY structure as a gas-sensitive material for a highly efficient room-temperature ammonia electrochemical sensor in the present invention. However, the present invention is not limited to the examples given.

[0051] The specific preparation process is as follows:

[0052] Simple room-temperature ammonia sensor assembly:

[0053] Take an appropriate amount of Compound 3 powder and add it to dichloromethane, and ultrasonically dissolve it until it is completely dissolved to obtain an orange-red transparent liquid. Then, slowly and evenly drop it on the silver interdigitated electrode, and wait for the solvent to evaporate completely automatically to obtain a flat and uniform coating. And age the sensor element at 120 °C for 12 h to improve the stability.

[0054] The specific detection steps are as follows:

[0055] The simple room-temperature ammonia sensor was prepared according to the above method. Then, the room-temperature ammonia sensor was placed in a gas chamber, and the gas chamber was maintained in a vacuum state (25 °C). The ammonia water with a corresponding concentration was quickly injected into the vacuum chamber by a micro syringe for gasification. The electrical signals at different concentrations were detected in real time through a Keithley 2612 data acquisition system. After stabilization, the vacuum pump was turned on to pump away the ammonia, and the recovery electrical signal of the device was continuously detected.

[0056] Figures 1 - 5 In it, Ra / Rg in the ordinate is the gas-sensing response. Ra: the response resistance of the gas-sensing element in air, and Rg: the response resistance of the gas-sensing element in the test gas.

[0057] Figures 1 - 5 The results show that the novel conjugated organic small molecule containing the BODIPY structure prepared by the present invention has very high response values, recovery properties and stability, has high selectivity to ammonia, and the change in the current-voltage characteristic diagram after ammonia treatment indicates that ammonia can significantly improve the conductivity of the small molecule.

[0058] Figures 6 - 8 The results show that the structure of organic molecule 3.5.7 is correct.

[0059] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. Application of a conjugated organic small molecule containing a BODIPY structure in an ammonia electrochemical sensor, characterized in that, The structural formula of the conjugated organic small molecule containing BODIPY structure is as follows:

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