Synthesis of a triphenylamine-based organic small molecule TPAY and its application in photocatalytic hydrogen evolution

Abstract

The application provides synthesis of an organic small molecule TPAY based on a triphenylamine group and application of the organic small molecule in photocatalytic hydrogen evolution, and belongs to the technical field of photocatalytic materials. The organic small molecule based on the triphenylamine group has a push-pull electron structure characteristic, and two triphenylamine groups are introduced into the molecular structure. The introduction of the triphenylamine group further expands the molecular conjugated plane, and is beneficial to improving intramolecular diffusion and dissociation of photo-generated excitons. The organic small molecule TPAY based on the triphenylamine group provided by the application is successfully used in photocatalytic hydrogen evolution experiments, good hydrogen evolution efficiency is obtained, and the performance is better than that of a corresponding organic small molecule Y6 without the triphenylamine group.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials technology, specifically relating to the synthesis of a small organic molecule TPAY based on a triphenylamine group and its application in photocatalytic hydrogen evolution. Background Technology

[0002] Photocatalytic hydrogen evolution technology has attracted much attention as a green and renewable method for hydrogen production. This technology utilizes sunlight to excite a catalyst, causing it to absorb photon energy and promote the splitting of water molecules to produce hydrogen and oxygen. It boasts advantages such as a wide range of energy sources, environmental friendliness, mild reaction conditions, and high energy efficiency, and is expected to become an important component of the future hydrogen energy industry. While inorganic semiconductor photocatalysts, such as titanium dioxide, can be used for photocatalytic hydrogen evolution, achieving high photocatalytic activity is difficult due to the weak absorption of visible light and poor tunability of their structure. To realize the commercial application of photocatalytic hydrogen production technology, developing new materials with diverse structures, broad absorption spectra, stable photochemical properties, and high hydrogen evolution efficiency is essential.

[0003] Based on this, organic semiconductor materials have attracted widespread attention due to their easily tunable molecular structures and controllable absorption spectra, such as covalent organic polymers (COP), conjugated microporous polymers (CMP), and covalent organic frameworks (COF). These organic semiconductor photocatalysts exhibit excellent performance, especially in the visible light region, demonstrating good hydrogen production efficiency, which is unattainable by many inorganic semiconductors. Notably, in recent years, researchers have attempted to use small organic molecule semiconductor materials, particularly ADA (Acceptor-Donor-Acceptor) type small molecule materials with push-pull electronic structure characteristics, for photocatalytic hydrogen evolution (HLE). Angew. Chem. Int. Ed. 2022, 61, e202114234; J. Am. Chem. Soc. 2022,144, 12747-12755; Angew. Chem. Int. Ed. (2023, 62, e202217989). Compared with traditional inorganic semiconductor photocatalysts, organic photovoltaic catalysts have advantages such as easily tunable molecular structure and broad spectral response, and are expected to utilize solar energy more efficiently.

[0004] Therefore, exploring the molecular structure design based on ADA-type organic small molecule semiconductor materials to achieve more efficient photocatalytic hydrogen evolution is an important research direction to promote the breakthrough development of solar water splitting for hydrogen production, a "green hydrogen" technology. Summary of the Invention

[0005] To explore the molecular structure design of ADA-type organic small molecule semiconductor materials and achieve more efficient photocatalytic hydrogen evolution, this invention provides the synthesis of a triphenylamine-based organic small molecule, TPAY. This triphenylamine-based organic small molecule exhibits a push-pull electron structure and incorporates two triphenylamine groups. The introduction of the triphenylamine groups further expands the molecular conjugation plane, which is beneficial for improving the intramolecular diffusion and dissociation of photoexcitons. This triphenylamine-based organic small molecule is helpful for further understanding the influence of the introduction of conjugated groups with significant steric hindrance on the structure-activity relationship of photocatalytic hydrogen evolution.

[0006] To achieve the above objectives, the present invention is implemented through the following scheme, and the molecular structure of an organic small molecule based on a triphenylamine group is as follows:

[0007]

[0008] This invention also provides a method for synthesizing the triphenylamine-based small organic molecule TPAY, comprising the following steps:

[0009] (1) Synthesis of compound X2: Under an inert atmosphere, compound X1, R1 and tetrakis(triphenylphosphine)palladium were added to a toluene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X2.

[0010] (2) Synthesis of compound X3: Under an inert atmosphere, compound X2 and triphenylphosphine were added to an o-dichlorobenzene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain a yellow solid crude product. Further, the crude product was added to an N,N-dimethylformamide solution with 2-ethylhexyl bromide, potassium carbonate, and potassium iodide. After the reaction was complete, the mixture was extracted and dried to obtain an orange liquid crude product. Further, the crude product was added to a tetrabutylammonium fluoride solution with tetrahydrofuran. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X3.

[0011] (3) Synthesis of compound X4: Under an inert atmosphere, compound X3 and N-bromosuccinimide were added to a tetrahydrofuran solution. After the reaction was complete, the compound X4 was obtained by column chromatography.

[0012] (4) Synthesis of compound X5: Under an inert atmosphere, compound X4 was added to anhydrous tetrahydrofuran solution, and a tetrahydrofuran solution of lithium diisopropylaminoacetate was slowly added dropwise to the system at -50°C; after the reaction was complete, N,N-dimethylformamide was added. After the reaction was complete again, the mixture was purified by column chromatography to obtain compound X5;

[0013] (5) Synthesis of compound X6: Under an inert atmosphere, compound X5, R2, potassium carbonate, methyltrioctylammonium chloride, and tetra(triphenylphosphine)palladium were added to a mixed solution of toluene and water. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X6.

[0014] (6) Synthesis of compound TPAY: At room temperature, compounds X6, R3, boron trifluoride ether, and acetic anhydride were added to toluene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain compound TPAY.

[0015]

[0016] Furthermore, the present invention also provides an application scheme for the aforementioned triphenylamine-based organic small molecule TPAY in photocatalytic hydrogen evolution technology, comprising the following steps: combining the triphenylamine-based organic small molecule with... p The polymer molecules were added to a chloroform solution, fully dissolved and blended, and then added to an aqueous solution of (3-thiophene)ethoxybutylsulfonate. The mixture was then sonicated to obtain a microemulsion. Further, the microemulsion was treated to remove the chloroform and then filtered to obtain nanoparticles suitable for photocatalytic hydrogen evolution technology.

[0017] in, p -Type polymer molecules, including but not limited to organic photovoltaic donor materials, such as PM6, D18, PTQ10, etc.

[0018] The present invention also tested the photocatalytic hydrogen evolution performance of the triphenylamine-based organic small molecule TPAY, and the results showed that its photocatalytic hydrogen evolution effect was better than that of the corresponding organic small molecule Y6 which does not contain a triphenylamine group.

[0019] The present invention has at least the following beneficial effects:

[0020] 1. Novel molecular structure design: This invention introduces the triphenylamine group into the ADA-type organic small molecule structure, which further expands the molecular conjugation plane and is beneficial to improving the intramolecular diffusion and dissociation of photogenerated excitons;

[0021] 2. More efficient photocatalytic hydrogen evolution: The photocatalytic hydrogen evolution performance of TPAY, an organic small molecule based on the triphenylamine group described in this invention, shows that its photocatalytic hydrogen evolution effect is better than that of the corresponding organic small molecule Y6, which does not contain the triphenylamine group.

[0022] 3. Deeper understanding of the structure-activity relationship of sterically hindered conjugated groups: By introducing a triphenylamine group with large steric hindrance, this invention helps to further understand the influence of the introduction of conjugated groups with large steric hindrance on the structure-activity relationship of photocatalytic hydrogen evolution. Attached Figure Description

[0023] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0024] Figure 1 The molecular structure of the small organic molecule TPAY synthesized in Example 1 is shown below.

[0025] Figure 2 This is a synthetic route diagram for the organic small molecule TPAY synthesized in Example 1;

[0026] Figure 3 The organic small molecule TPAY synthesized in Example 1 1 H NMR spectrum;

[0027] Figure 4 The MS mass spectrum of the small organic molecule TPAY synthesized in Example 1;

[0028] Figure 5 The molecular structures of Y6, an organic small molecule without triphenylamine groups, and polymer molecules PM6, D18, and PTQ10 are shown.

[0029] Figure 6 This is a comparison chart of the photocatalytic hydrogen evolution performance of nanoparticles based on the organic small molecule TPAY and the organic small molecule Y6 without the triphenylamine group in Example 2. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0031] Numerous specific details are set forth in the following description to provide a thorough understanding of the invention; however, the invention may also be practiced in other ways different from those described herein. All other embodiments obtained by those skilled in the art based on the embodiments described herein are within the scope of protection of this invention.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0033] The materials and reagents used in this embodiment and the comparative example are all commercially available products.

[0034] Example 1

[0035] This embodiment provides details of the synthesis of the organic small molecule TPAY, including the following steps:

[0036] (1) Synthesis of compound X2: Compound X1, R1 and tetrakis(triphenylphosphine)palladium were added to toluene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X2.

[0037] Compound X1 (3 g, 7.82 mmol), R1 (8.62 g, 18.76 mmol), and tetrakis(triphenylphosphine)palladium (0.45 g, 0.39 mmol) were added to a toluene solution (35 mL) under an inert atmosphere at a reaction temperature of 120 °C. After complete reaction, the mixture was extracted, distilled under reduced pressure, and purified by column chromatography using PE / DCM (5:1) as the eluent to give compound X2 (red solid, 4.53 g, 71%).

[0038] (2) Synthesis of compound X3: Under an inert atmosphere, compound X2 (4 g, 4.91 mmol) and triphenylphosphine (6.44 g, 24.54 mmol) were added to o-dichlorobenzene solution at 180 °C. After the reaction was complete, the mixture was extracted, distilled under reduced pressure, and purified by column chromatography with PE / DCM (1:2) as the eluent, yielding a yellow solid crude product. Further, this crude product was added to 80 mL of N,N-dimethylformamide solution with 2-ethylhexyl bromide (9.48 g, 49.10 mmol), potassium carbonate (2.71 g, 19.64 mmol), and potassium iodide (7.34 g, 44.19 mmol), and the reaction was carried out at 80 °C. After the reaction was complete, the mixture was extracted and distilled under reduced pressure, yielding an orange liquid crude product. Furthermore, the crude product was added to a tetrabutylammonium fluoride solution (1 M, 49.10 mL, 49.10 mmol), and after reacting fully at room temperature, it was extracted, distilled under reduced pressure, and purified by column chromatography with PE / DCM (5:1) as the eluent to obtain compound X3 (orange liquid, 2.13 g, 66%).

[0039] (3) Synthesis of compound X4: Under an inert atmosphere, compound X3 (2 g, 3.02 mmol) and N-bromosuccinimide (4.29 g, 24.14 mmol) were added to tetrahydrofuran solution (30 mL). After the reaction was carried out at room temperature, the mixture was extracted, distilled under reduced pressure, and purified by column chromatography with PE / DCM (4:1) as the eluent to obtain compound X4 (orange solid, 2.11 g, 85%).

[0040] (4) Synthesis of compound X5: Compound X4 (2 g, 2.44 mmol) was added to anhydrous tetrahydrofuran solution (40 mL) under an inert atmosphere. A tetrahydrofuran solution of lithium diisopropylaminoacetate (2 M, 6.09 mL, 12.19 mmol) was slowly added dropwise to the system at -50°C, and the reaction was carried out at room temperature for 4 hours. Subsequently, N,N-dimethylformamide (1.88 mL) was added. After a second complete reaction, the mixture was extracted, distilled under reduced pressure, and purified by column chromatography using PE / DCM (1:4) as the eluent to obtain compound X5 (orange solid, 1.38 g, 65%).

[0041] (5) Synthesis of compound X6: Under an inert atmosphere, compound X5 (0.1 g, 0.12 mmol), R2 (1.14 mmol), potassium carbonate (0.79 g, 0.57 mmol), methyltrioctylammonium chloride (2 drops), and tetrakis(triphenylphosphine)palladium (6.59 mg, 0.0057 mmol) were added to a mixed solution of toluene and water (12 mL: 6 mL) at a reaction temperature of 110 °C. After the reaction was complete, the mixture was extracted and distilled under reduced pressure to obtain compound X6, which could be directly proceeded to the next step without further purification.

[0042] (6) Synthesis of compound TPAY: Compound X6 (236.8 mg, 0.1 mmol), R3 (51.8 mg, 0.22 mmol), boron trifluoride ether (319.4 mg, 2.25 mmol), and acetic anhydride (0.1 mL) were added to toluene solution (5 mL). After reacting fully at room temperature, the compound TPAY was obtained by column chromatography.

[0043] Example 2

[0044] This embodiment provides a method for preparing nanoparticles based on the organic small molecule TPAY and its photocatalytic hydrogen evolution performance test, including the following steps:

[0045] organic small molecule TPAY and p A type-1 polymer molecule (1:1 wt%) was added to a chloroform solution (0.5 mg / mL) and heated to 50 °C to ensure complete dissolution. Subsequently, this blend (5 mL) was added to an aqueous solution of (3-thiophene)ethoxybutylsulfonate (15 mL, 0.5 wt%), and the mixture was sonicated to obtain a microemulsion. Further, after removing the chloroform from the microemulsion by vacuum distillation, the mixture was filtered through a 0.5 μm filter membrane to obtain nanoparticles suitable for photocatalytic hydrogen evolution technology.

[0046] Subsequently, a commercially available photocatalytic hydrogen evolution system was used for testing. A xenon lamp was used as the light source, and the system was circulated every 5 hours. The amount of hydrogen produced was monitored by gas chromatography to obtain the corresponding hydrogen production efficiency.

[0047] Compare with Example 1

[0048] To demonstrate the superiority of this invention, a small organic molecule Y6 (whose molecular structure is as follows) without a triphenylamine group is used. Figure 5 As shown in the figure, nanoparticles were prepared and hydrogen evolution tests were performed using the exact same method as in Example 2.

[0049] Result: As Figure 6 As shown, the hydrogen evolution yield per unit time of nanoparticles based on the PM6:TPAY system is significantly higher than that of the corresponding PM6:Y6 system. Meanwhile, the systems based on D18:TPAY and PTQ10:TPAY also achieved good hydrogen evolution yields per unit time. These results confirm that the present invention significantly improves the hydrogen evolution performance of organic small molecule TPAY photocatalysts by introducing triphenylamine groups, and its performance is superior to that of the corresponding organic small molecule Y6 without triphenylamine groups.

[0050] In summary, the supported organic photocatalyst nanoparticles of the present invention have good hydrogen evolution efficiency, which broadens the application scenarios of photocatalytic materials.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A small organic molecule TPAY based on a triphenylamine group, characterized in that, The molecular structure of the triphenylamine-based organic small molecule TPAY is as follows: 。 2. The method for synthesizing TPAY, an organic small molecule based on a triphenylamine group, according to claim 1, is characterized in that, Includes the following steps: ； (1) Synthesis of compound X2: Under an inert atmosphere, compound X1, R1 and tetrakis(triphenylphosphine)palladium were added to a toluene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X2. (2) Synthesis of compound X3: Under an inert atmosphere, compound X2 and triphenylphosphine were added to o-dichlorobenzene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain a yellow solid crude product. The crude product was added to N,N-dimethylformamide solution with 2-ethylhexyl bromide, potassium carbonate, and potassium iodide. After the reaction was complete, the mixture was extracted and dried to obtain an orange liquid crude product. The crude product was added to tetrabutylammonium fluoride solution with tetrahydrofuran. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X3. (3) Synthesis of compound X4: Under an inert atmosphere, compound X3 and N-bromosuccinimide were added to a tetrahydrofuran solution. After the reaction was complete, the compound X4 was obtained by column chromatography. (4) Synthesis of compound X5: Under an inert atmosphere, compound X4 was added to anhydrous tetrahydrofuran solution, and a tetrahydrofuran solution of diisopropylaminolithium was slowly added dropwise to the system at minus fifty degrees Celsius. After the reaction was complete, N,N-dimethylformamide was added; after another complete reaction, the mixture was purified by column chromatography to obtain compound X5. (5) Synthesis of compound X6: Under an inert atmosphere, compound X5, R2, potassium carbonate, methyltrioctylammonium chloride, and tetra(triphenylphosphine)palladium were added to a mixed solution of toluene and water. After the reaction was complete, the mixture was purified by column chromatography to obtain compound X6. (6) Synthesis of compound TPAY: At room temperature, compounds X6, R3, boron trifluoride ether, and acetic anhydride were added to toluene solution. After the reaction was complete, the mixture was purified by column chromatography to obtain compound TPAY.

3. The application of TPAY, an organic small molecule based on a triphenylamine group, in photocatalytic hydrogen evolution technology according to claim 1.

4. The application of the triphenylamine-based organic small molecule TPAY in photocatalytic hydrogen evolution technology according to claim 3, characterized in that, The triphenylamine-based organic small molecule TPAY was blended with p-type polymer molecules to prepare corresponding nanoparticles, which were then applied to photocatalytic hydrogen evolution technology.

5. The application according to claim 4, characterized in that: The p-type polymer molecule is an organic photovoltaic donor material.

6. The application according to claim 5, characterized in that: The organic photovoltaic donor material is one of PM6, D18 or PTQ10; The molecular structure of PM6 is as follows: ； The molecular structure of D18 is as follows: ； The molecular structure of PTQ10 is as follows: 。 7. A nanoparticle for photocatalytic hydrogen evolution, characterized in that: It is composed of the organic small molecule TPAY based on the triphenylamine group as described in claim 1 and p-type polymer molecules.

8. A method for preparing nanoparticles for photocatalytic hydrogen evolution, used to prepare the nanoparticles for photocatalytic hydrogen evolution as described in claim 7, characterized in that, The triphenylamine-based organic small molecule TPAY and the p-type polymer molecule were added to a chloroform solution and fully dissolved and mixed. Then, the mixture was added to an aqueous solution of (3-thiophene)ethoxybutylsulfonate and ultrasonically treated to obtain a microemulsion. After removing the chloroform from the microemulsion, it was filtered to obtain nanoparticles.

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