Method for synthesizing acetylene conjugated microporous polymers by ultrasound-chemical promoted sonogashira coupling reaction and application thereof

Abstract

The application relates to a method for synthesizing acetylenyl conjugated microporous polymer through an ultrasonic chemistry promoted Sonogashira coupling reaction and application thereof in the field of photocatalysis, and belongs to the cross field of functional polymer materials and photocatalyst preparation technology. In the method, terminal alkyne, aryl bromide, a palladium catalyst and a copper co-catalyst are uniformly dispersed in a mixed solvent of N,N-dimethylformamide and triethylamine according to a stoichiometric ratio to form a precursor solution; the precursor solution is placed in an ultrasonic generator under the condition of room temperature and nitrogen flow for a certain time to trigger a Sonogashira cross coupling and a subsequent polymerization process in situ; after the reaction is completed, a solid product is obtained through vacuum filtration and washing to obtain acetylenyl conjugated microporous polymer. Compared with a traditional solvothermal method, the method has the advantages of mild reaction conditions (room temperature, no external heating), low energy consumption, short reaction time, few side reactions, environmental friendliness and the like, and has good process expandability and is suitable for large-scale preparation.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of functional polymer materials and photocatalyst preparation technology, and in particular to a method for synthesizing alkynyl conjugated microporous polymers by promoting the Sonogashira coupling reaction by ultrasound chemistry and its application. Background Technology

[0002] The Sonogashira coupling reaction is an important branch of palladium-catalyzed cross-coupling reactions, which can efficiently construct carbon-carbon triple bonds under mild conditions, achieving high selectivity of C(sp) bonds between terminal alkynes and aryl (or vinyl) halides. 2 The Sonogashira reaction involves C-C (sp) bond coupling. Due to its advantages such as good functional group tolerance, wide substrate applicability, and relatively controllable reaction conditions, this reaction has been widely applied in drug molecule framework construction, conjugated functional material design, and fine chemical synthesis. Traditional Sonogashira reactions are mostly heat-driven (80-160°C), and generally suffer from problems such as high reaction temperature, high energy consumption, long reaction cycle (8-72 h), and difficulty in suppressing side reactions (Glaser dimerization, Heck coupling), which restricts its further application in large-scale preparation and green chemistry practices.

[0003] Sonochemistry, as a non-thermally activated physical enhancement technique, has demonstrated significant advantages in organic synthesis and the preparation of advanced functional materials in recent years. Its core mechanism lies in the acoustic cavitation effect. When high-intensity ultrasonic waves with frequencies ≥20 kHz irradiate a liquid medium, they can induce the oscillation, growth, and eventual violent implosion of tiny gas nuclei, instantaneously generating localized high temperatures (~5000 K), high pressures (~100 MPa), strong shear forces, high-speed microjets (>100 m / s), and active free radicals (such as H and OH). These extreme microenvironments can not only significantly accelerate mass transfer and interface renewal, improving reactant contact efficiency, but also regulate nucleation kinetics, inhibit abnormal grain growth, and induce defect engineering or phase transition behavior in specific systems. Currently, sonochemistry strategies have been successfully validated in the rapid, low-temperature, and controllable synthesis of various functional materials, including metal oxides, metal sulfides, graphene derivatives, metal-organic frameworks, and covalent organic frameworks (Coordination Chemistry Reviews, 2025, 526, 216373).

[0004] However, in the field of polymer synthesis, the application of sonicochemical synthesis methods for various material systems constructed by irreversible covalent bonds (such as conjugated microporous polymers, hypercrosslinked polymers, and self-microporous polymers) is still relatively rare. The main limiting factor is the sensitivity of the irreversible bonding process to reaction conditions. Among them, the research on using sonicochemistry to promote the Sonogashira coupling reaction to construct alkynyl conjugated microporous polymers has not been reported to date. Its technical bottleneck mainly stems from the following two aspects: (1) The local high temperature and free radical environment generated by ultrasonic cavitation easily induce the oxidation of terminal alkynes to Glaser self-coupling side reaction. This side reaction path competes with the target cross-coupling, which may lead to uncontrolled polymer cross-linking, breakage of the π-conjugated system, and collapse of the microporous structure; (2) The ultrasonic cavitation process is accompanied by a significant gas entrainment effect, which easily increases the oxygen content of the system. The key catalytic species in Sonogashira coupling (such as Pd) 0 / Pd 2+ With Cu + (e.g.) are extremely sensitive to oxygen; even trace amounts of dissolved oxygen can lead to irreversible oxidation and deactivation of the catalyst. Therefore, to achieve high selectivity, high conversion rate, and high reproducibility of the Sonogashira coupling reaction under an ultrasonic field, three key elements need to be optimized: (1) accurately matching ultrasonic parameters (such as power, pulse mode, and amplitude transformer geometry) to balance activation efficiency and side reaction suppression; (2) strictly controlling the reaction atmosphere (nitrogen protection) and the closed operation process to ensure an oxygen-free system; and (3) rationally designing the feeding sequence and precursor pre-dispersion strategy to avoid excessively high local concentrations that could lead to explosive polymerization. The above-mentioned multi-parameter coupling and regulation mechanism constitutes the key scientific problem and technological breakthrough in the field for achieving green, efficient, and scalable synthesis of alkynyl conjugated microporous polymers. Summary of the Invention

[0005] This invention aims to overcome the bottlenecks in the synthesis of conjugated microporous polymers by traditional thermally driven Sonogashira coupling reactions, such as reaction kinetic stagnation, uncontrollable side reactions, and insufficient structural regularity. It proposes a new strategy for the controllable construction of alkynyl conjugated microporous polymers based on ultrasonic field promotion.

[0006] A method for synthesizing alkynyl conjugated microporous polymers via sonochemically promoted Sonogashira coupling reaction, characterized by comprising the following steps:

[0007] Step 1: Add terminal alkyne, aryl bromide, palladium catalyst and copper co-catalyst to a mixed solvent composed of N,N-dimethylformamide and triethylamine in stoichiometric ratio, and stir at room temperature until completely dissolved to form a precursor solution;

[0008] Step 2: The precursor solution is placed in an ultrasonic generator and subjected to intermittent ultrasonic treatment using an amplitude transformer under nitrogen gas flow conditions to induce Sonogashira cross-coupling and in-situ polymerization reactions at room temperature.

[0009] Step 3: After the reaction is complete, the resulting reaction mixture is filtered under reduced pressure, washed, and dried under vacuum to obtain an alkynyl conjugated microporous polymer.

[0010] The molar ratio of the terminal alkyne to the aryl bromide is 3:1 to 1:2;

[0011] The ultrasonic frequency is 20-25 kHz with automatic tracking, the output power is 450-650 W, the diameter of the amplitude transformer end is 2-10 mm, the ultrasonic pulse mode is "on for 3-7 s, off for 2-5 s", and the cumulative response time is 0.5-3.0 h.

[0012] The terminal alkyne monomer is any one of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene, and 1,2,4,5-tetraethynylbenzene.

[0013] The aryl bromide is any one of 1,4-dibromobenzene, 1,3,5-tribromobenzene, 1,2,4,5-tetrabromobenzene, and hexabromobenzene.

[0014] In step 1, the terminal alkyne is 1,4-diethynylbenzene and the aryl bromide is 1,3,5-tribromobenzene; or the terminal alkyne is 1,2,4,5-tetraethynylbenzene and the aryl bromide is 1,4-dibromobenzene; or the terminal alkyne is 1,4-diethynylbenzene and the aryl bromide is hexabromobenzene; or the terminal alkyne is 1,4-diethynylbenzene and the aryl bromide is 1,2,4,5-tetrabromobenzene; or the terminal alkyne is 1,3,5-triethynylbenzene and the aryl bromide is 1,4-dibromobenzene.

[0015] The palladium catalyst is tetra(triphenylphosphine)palladium, and the copper co-catalyst is cuprous iodide.

[0016] The volume ratio of N,N-dimethylformamide to triethylamine is 1:3 to 3:1.

[0017] The concentration of the C-Br reaction site in the precursor solution is 0.10-0.25 mol / L.

[0018] The low-pressure filtration, washing, and vacuum drying processes involve washing with N,N-dimethylformamide, hot water, and methanol at least three times each, followed by vacuum drying at 60-120°C for 4-24 hours.

[0019] Application of sonochemistry-promoted Sonogashira coupling reaction for the synthesis of alkynyl conjugated microporous polymers in photocatalytic H2O2 production.

[0020] The specific steps for the synthesis of alkynyl conjugated microporous polymers through sonication-promoted Sonogashira coupling reaction, applied to photocatalytic H2O2 production, are as follows:

[0021] S1, a suspension is obtained by adding deionized water and anhydrous ethanol to the alkynyl conjugated microporous polymer seed;

[0022] S2, the suspension is ultrasonically treated with an ultrasonic cleaner to ensure full dispersion, and then high-purity oxygen is bubbled through at room temperature to make the reaction system reach oxygen saturation.

[0023] S3, during the reaction process, high-purity oxygen is continuously introduced to maintain an oxygen-rich atmosphere, and photocatalytic reaction is carried out at room temperature and under light irradiation to produce H2O2.

[0024] This invention induces transient high temperature (≈5000 K), high pressure (≈100 MPa) microregions and high intensity microjets (>100 m / s) in N,N-dimethylformamide / triethylamine mixed solvents through ultrasonic cavitation effect. This not only significantly promotes mass transfer and interface renewal of reactants, but also accelerates the palladium / copper co-catalytic cycle from both kinetic and thermodynamic dimensions. Specifically, in the Pd(PPh3)4 / CuI co-catalytic system, ultrasound synergistically promotes the reaction through the following pathways: (1) Microjet shearing and high-frequency oscillation effectively enhance the activity of Pd(0) species Pd 0 (PPh3)2 dispersion stability, inhibit its aggregation and deactivation, and accelerate its oxidative addition with aryl bromides to generate the key three-coordinate Pd(II) intermediate Ph3P-Pd(II)(Ar)-Br; (2) Triethylamine-mediated deprotonation of terminal alkyne to form the copper alkynyl(I) complex Cu-C≡CR in situ. Ultrasound enhances the migration rate and collision frequency of this complex in solution, thereby efficiently completing the transmetallation with the Pd(II) intermediate to generate the dual organic Pd(II) species Ph3P-Pd(II)(Ar)-(C≡CR); (3) Local transient high temperature significantly reduces the reduction elimination energy barrier, promoting the rapid dissociation of the Pd(II) species to generate the target C(sp 2 )-C(sp) coupling products, and simultaneously regenerated Pd 0 (PPh3)2 reacts with CuI to complete a bimetallic catalytic cycle. Notably, the use of intermittent ultrasonic mode ("on 3-7 s / off 2-5 s") can accelerate reaction kinetics while utilizing the off-period to dissipate heat and relax intermediate configurations, avoiding side reactions such as Glaser self-coupling caused by continuous high energy input. This ensures regioselectivity and controllable polymerization, rapidly constructing alkynyl conjugated polymers.

[0025] This method requires no external heating or high-pressure reactors; it can be completed with just a conventional ultrasonic generator. It has significant advantages such as simple process, short reaction cycle (0.5-2 h), high operational safety, and good repeatability.

[0026] The obtained polymer exhibits excellent reaction rates (759.7-4478.7 μmol·g⁻¹) when catalyzed by the selective two-electron reduction of O₂ to H₂O₂ under visible light (λ ≥ 420 nm). -1 ·h -1 It exhibits excellent cycling stability (H2O2 yield retention ≥82% after 4 consecutive cycles), providing a novel photocatalyst system that combines scientific originality and engineering feasibility for the development of an efficient, stable, and green photocatalytic oxidation platform. Attached Figure Description

[0027] Figure 1 The structural formulas for the terminal alkynes and aryl bromides of this invention are shown below.

[0028] Figure 2 The polymers synthesized in Examples 1, 2, and 3 are as follows.

[0029] Figure 3 Fourier transform infrared spectra of polymers in Examples 1, 2, and 3.

[0030] Figure 4 The graph shows the reaction time-yield relationship of polymers 1, 2, and 3 in the H2O / ethanol system for the production of H2O2.

[0031] Figure 5 The graph shows the time-yield relationship of the reaction between polymers in Examples 1, 2, and 3 for the production of H2O2 from H2O / benzyl alcohol.

[0032] Figure 6 The figure shows the results of the cyclic experiment for polymer-generated H2O2.

[0033] Figure 7 The graph shows the reaction time-yield relationship for the synthesis of CMP-Te to H2O2 in an H2O / ethanol system using the classic solvothermal method.

[0034] Figure 8 This is a diagram of the reaction process of the present invention. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to the embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0036] Example 1: A method for synthesizing the alkynyl conjugated microporous polymer sonoCMP-Tr by promoting the Sonogashira coupling reaction using sonicochemistry. The specific steps are as follows:

[0037] S1, Weigh 319 mg of 1,3,5-tribromobenzene, 192 mg of 1,4-diethynylbenzene, 140 mg of tetrakis(triphenylphosphine)palladium, and 70 mg of cuprous iodide into a reaction tube. Measure 8.4 mL of N,N-dimethylformamide and 8.4 mL of triethylamine into the reaction tube to form a mixture.

[0038] S2, under nitrogen gas flow conditions, the mixture was placed under a titanium alloy amplitude transformer with a diameter of 6 mm for ultrasonication. The ultrasonic frequency was 20-25 kHz with automatic tracking, the ultrasonic power was 500 W, and the process was alternately turned on for 3 seconds and off for 3 seconds, with a total reaction time of 2 hours.

[0039] S3, the reaction solution after the reaction was completed was washed by vacuum filtration with N,N-dimethylformamide, hot water and methanol in sequence, and the resulting solid powder was dried in a vacuum drying oven at 65 °C for 8 h, with a polymer yield of 91%.

[0040] The sonoCMP-Tr obtained in this embodiment is applied to the photocatalytic production of H2O2. The specific steps are as follows:

[0041] S1, accurately weigh 2 mg sonoCMP-Tr into a beaker, add 9 mL of deionized water and 1 mL of anhydrous ethanol to obtain a suspension;

[0042] S2, the suspension is ultrasonically treated with an ultrasonic cleaner for 10 min to ensure full dispersion, and then high-purity oxygen is bubbled through at room temperature for 20 min to make the reaction system reach oxygen saturation.

[0043] S3, during the reaction, high-purity oxygen is continuously introduced to maintain an oxygen-rich atmosphere, at room temperature and under a xenon lamp (λ ≥ 420 nm, light intensity 800 W / m²). 2 The photocatalytic reaction was carried out under irradiation; samples were taken every 20 min, and the supernatant was taken after centrifugation at 8000 rpm for 5 min. The H2O2 concentration was detected by peroxidase colorimetric method, and the yield of catalyst per unit mass was calculated accordingly.

[0044] Example 2: A method for synthesizing the alkynyl conjugated microporous polymer sonoCMP-Te by promoting the Sonogashira coupling reaction using sonication chemistry, the specific steps of which are as follows:

[0045] S1. Weigh 300 mg of 1,2,4,5-tetrabromobenzene, 192 mg of 1,4-diethynylbenzene, 140 mg of tetra(triphenylphosphine)palladium, and 70 mg of cuprous iodide into a reaction tube. Measure 8 mL of N,N-dimethylformamide and 8 mL of triethylamine into the reaction tube and stir thoroughly to form a precursor solution.

[0046] S2, under nitrogen gas flow conditions, the precursor solution was placed under a 6 mm diameter amplitude transformer for ultrasonication. The ultrasonic frequency was 20-25 kHz with automatic tracking, the ultrasonic power was 540 W, and the cycle was alternately turned on for 5 s and off for 3 s, with a total reaction time of 2 h.

[0047] S3. After the reaction was complete, the reaction solution was washed sequentially with N,N-dimethylformamide, hot water and methanol by vacuum filtration. The resulting solid powder was placed in a drying oven at 65 °C and dried under vacuum for 4 h. The polymer yield was 93%.

[0048] The sonoCMP-Te obtained in this embodiment is applied to the photocatalytic production of H2O2. The specific steps are as follows:

[0049] S1, accurately weigh 2 mg sonoCMP-Te into a beaker, add 9 mL of deionized water and 1 mL of anhydrous ethanol to obtain a suspension;

[0050] S2, the suspension is ultrasonically treated with an ultrasonic cleaner for 10 min to ensure full dispersion, and then high-purity oxygen is bubbled through at room temperature for 20 min to make the reaction system reach oxygen saturation.

[0051] S3, during the reaction, high-purity oxygen is continuously introduced to maintain an oxygen-rich atmosphere, at room temperature and under a xenon lamp (λ ≥ 420 nm, light intensity 500 W / m²). 2 The photocatalytic reaction was carried out under irradiation; samples were taken every 20 min, and the supernatant was taken after centrifugation at 8000 rpm for 5 min. The H2O2 concentration was detected by peroxidase colorimetric method, and the yield of catalyst per unit mass was calculated accordingly.

[0052] Example 3: A method for synthesizing the alkynyl conjugated microporous polymer sonoCMP-He by promoting the Sonogashira coupling reaction using sonicochemistry. The specific steps are as follows:

[0053] S1, weigh 279 mg hexabromobenzene, 192 mg 1,4-diethynylbenzene, 140 mg tetra(triphenylphosphine)palladium, and 70 mg cuprous iodide into a reaction tube. Measure 10 mL of N,N-dimethylformamide and 10 mL of triethylamine into the reaction tube to form a precursor solution.

[0054] S2, under nitrogen gas flow conditions, the precursor solution was placed under a 6 mm diameter amplitude transformer for ultrasonication. The ultrasonic frequency was 20-25 kHz with automatic tracking, the ultrasonic power was 450 W, and the cycle was alternately turned on for 4 s and off for 5 s, with a total reaction time of 3 h.

[0055] S3. After the reaction was complete, the reaction solution was washed sequentially with N,N-dimethylformamide, hot water and methanol by vacuum filtration. The resulting solid powder was dried in a vacuum drying oven at 65 °C for 12 h. The polymer yield was 89%.

[0056] The sonoCMP-He obtained in this embodiment is applied to the photocatalytic production of H2O2. The specific steps are as follows:

[0057] S1. Accurately weigh 2 mg sonoCMP-He into a beaker, add 9 mL of deionized water and 1 mL of anhydrous ethanol to obtain a suspension;

[0058] S2, the suspension is ultrasonically treated with an ultrasonic cleaner for 10 min to ensure full dispersion, and then high-purity oxygen is bubbled through at room temperature for 20 min to make the reaction system reach oxygen saturation.

[0059] S3, during the reaction, high-purity oxygen is continuously introduced to maintain an oxygen-rich atmosphere, at room temperature and under a xenon lamp (λ ≥ 420 nm, light intensity 800 W / m²). 2 The photocatalytic reaction was carried out under irradiation; samples were taken every 20 min, and the supernatant was taken after centrifugation at 8000 rpm for 5 min. The H2O2 concentration was detected by peroxidase colorimetric method, and the yield of catalyst per unit mass was calculated accordingly.

[0060] The polymers sonoCMP-Tr, sonoCMP-Te, and sonoCMP-He synthesized in Examples 1-3 were characterized by Fourier transform infrared spectroscopy, such as... Figure 3 As shown. After 2 hours of ultrasonic reaction, 1300 cm⁻¹ of polymer powder... -1 The stretching vibration peak of C-Br at 2210 cm⁻¹ disappears, while the peak at 2210 cm⁻¹ disappears. -1 The presence of characteristic peaks of alkynyl groups (-C≡C-) indicates that the polymer was successfully constructed.

[0061] like Figure 4 As shown, in a pure water / ethanol (9 / 1, v / v) system, the average yields of H2O2 for the polymers sonoCMP-Tr, sonoCMP-Te, and sonoCMP-He synthesized in steps 1-3, respectively, reached 759.7 μmol·g. -1 ·h -1 2425.9 μmol·g -1 ·h -11835.1 μmol·g -1 ·h -1 When ethanol in S1 was replaced with an equal volume of benzyl alcohol, and other conditions remained unchanged, the H2O2 yields of the polymers sonoCMP-Tr, sonoCMP-Te, and sonoCMP-He synthesized in steps 1-3 respectively increased to 822.9 μmol·g. -1 ·h -1 4478.7 μmol·g -1 ·h -1 2234.9 μmol·g -1 ·h -1 ,like Figure 5 As shown.

[0062] A polymer (labeled CMP-Te, yield 76%) synthesized from the same raw materials as sonoCMP-Te using the classic solvothermal method (120 °C, 72 h) achieved an average H2O2 yield of 1683.2 μmol·g in a pure water / ethanol (9 / 1, v / v) system. -1 ·h -1 ,like Figure 7 As shown, compared to the solvothermal method, ultrasound-assisted synthesis not only significantly shortens the reaction cycle (from 72 h to 2 h), but also endows the material with higher intrinsic catalytic activity and interfacial reaction kinetic efficiency by enhancing mass transfer and regulating the order of the conjugated framework.

[0063] Cyclic stability experiments were conducted in a water-benzyl alcohol mixed solvent system, such as... Figure 6 As shown, after four cycles (2 h each time), sonoCMP-Tr still maintained 95% of the initial H2O2 yield, sonoCMP-Te still maintained 82% of the initial H2O2 yield, and sonoCMP-He still maintained 90% of the initial H2O2 yield, all exhibiting good structural stability and catalytic durability.

[0064] The ultrasonic synthesis method disclosed in this invention has unique advantages when applied to alkynyl conjugated polymers and is not a direct extension of existing technologies in the field of materials synthesis. To achieve efficient and controllable synthesis, the applicant, based on the physicochemical mechanism of ultrasound and combined with the characteristics of the Sonogashira reaction, systematically conducted innovative optimization of the parameter system and in-depth exploration of reaction conditions, including key variables such as ultrasonic intensity, pulse mode, reaction concentration, temperature synergistic control, and monomer feed kinetics, ultimately establishing the stable technical solution described in this invention. Typical comparative examples are as follows:

[0065] Comparative Example 1: 100 mg of 1,2,4,5-tetrabromobenzene, 64 mg of 1,4-diethynylbenzene, 47 mg of tetra(triphenylphosphine)palladium, 23 mg of cuprous iodide, 8 mL of N,N-dimethylformamide, and 8 mL of triethylamine were added to a reaction tube. The mixture was stirred thoroughly under a nitrogen stream and sonicated using a 6 mm diameter amplitude transformer at an automatic tracking frequency of 20-25 kHz and a power of 540 W. The sonication was alternately turned on for 5 seconds and off for 3 seconds, with a total reaction time of 3 hours. After the reaction was complete, the reaction solution was washed sequentially with N,N-dimethylformamide, hot water, and methanol by centrifugation. No solid polymer was obtained, indicating that the coupling polymerization reaction under these low concentration conditions failed to start effectively.

[0066] Comparative Example 2: 400 mg of 1,2,4,5-tetrabromobenzene, 256 mg of 1,4-diacetylenebenzene, 188 mg of tetra(triphenylphosphine)palladium, 92 mg of cuprous iodide, 8 mL of N,N-dimethylformamide, and 8 mL of triethylamine were added to a reaction tube. The mixture was stirred thoroughly under a nitrogen stream and sonicated using a 6 mm diameter amplitude transformer at an automatic tracking frequency of 20-25 kHz and a power of 540 W. The sonication was alternately on for 5 seconds and off for 3 seconds, with a total reaction time of 1 h. The reaction system was noticeably viscous. After the reaction was complete, the reaction solution was washed sequentially with N,N-dimethylformamide, hot water, and methanol by centrifugation and vacuum drying. The polymer was difficult to grind into a uniform powder, with a yield of 157%. Excessively high monomer concentration not only exacerbated side reactions such as dehalogenation, oligomerization, and crosslinking, but also caused a large amount of palladium-based catalyst to embed in the polymer in the form of nanoclusters, resulting in the failure of subsequent purification and severely impairing both the purity and structural integrity of the product. The concentration of C-Br active sites in this reaction is 0.38 mol / L, which is feasible in other ultrasonic chemical material systems and in conventional solvothermal synthesis of polymer systems via Sonogashira coupling reaction.

[0067] The concentration of the C-Br active site in Comparative Example 1 was 0.06 mol / L, and in Comparative Example 2 it was 0.38 mol / L. Although both fall within the concentration range reported in the literature for conventional solvothermal Sonogashira coupling polymerization (typical conditions: Pd(PPh3)4 / CuI catalytic system, 120-150°C, reaction time 24-72 h) and some ultrasound-promoted synthesis of inorganic or covalent organic frameworks, metal-organic frameworks, etc. (Applied Catalysis B: Environment and Energy, 2026, 380, 125778; Ultrasonics Sonochemistry, 2026, 124, 107700; Ultrasonics Sonochemistry, 2024, 106, 106903), their applicability is significantly limited in this ultrasound-promoted Sonogashira reaction system for synthesizing many alkynyl conjugated polymers: a concentration of 0.06 mol / L is too low to ensure the effective collision frequency and chain growth persistence of the palladium active center in the ultrasonic cavitation microenvironment, causing the polymerization reaction to fail to start; while 0.38 Excessive mol / L concentration induces side reactions, resulting in catalyst encapsulation and irregular product structures. The above comparison fully demonstrates that the optimized concentration window (0.10-0.25 mol / L) of C-Br active sites established in this invention is a key parameter for balancing reaction kinetics, selectivity, and product structural integrity, and has a decisive influence on the efficiency, repeatability, and scalability of this type of ultrasound-driven conjugated polymerization process.

[0068] Comparative Example 3: 300 mg of 1,2,4,5-tetrabromobenzene, 192 mg of 1,4-diethynylbenzene, 140 mg of tetra(triphenylphosphine)palladium, and 70 mg of cuprous iodide were added to a reaction tube. 8 mL of N,N-dimethylformamide and 8 mL of triethylamine were measured and added. The mixture was stirred thoroughly under a nitrogen stream and sonicated using a 6 mm diameter amplitude transformer at an automatically tracked frequency of 20-25 kHz and a power of 400 W. The sonication was alternately turned on for 5 seconds and off for 3 seconds, with a total reaction time of 3 h. After the reaction, the reaction solution was washed sequentially with N,N-dimethylformamide, hot water, and methanol by centrifugation. No solid polymer was obtained. Under these ultrasonic power conditions, the cavitation effect was insufficient to effectively initiate the palladium catalytic cycle, and the coupling reaction remained stalled at the initial stage, even though this power was comparable to the ultrasonic power conditions for the synthesis of most materials (Coordination Chemistry Reviews, 2025, 526, 216373).

Claims

1. A method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction, characterized in that, Includes the following steps: Step 1: Add terminal alkyne, aryl bromide, palladium catalyst and copper co-catalyst to a mixed solvent composed of N,N-dimethylformamide and triethylamine in stoichiometric ratio, and stir at room temperature until completely dissolved to form a precursor solution; Step 2: The precursor solution is placed in an ultrasonic generator and subjected to intermittent ultrasonic treatment using an amplitude transformer under nitrogen gas flow conditions to induce Sonogashira cross-coupling and in-situ polymerization reactions at room temperature. Step 3: After the reaction is complete, the resulting reaction mixture is filtered under reduced pressure, washed, and dried under vacuum to obtain an alkynyl conjugated microporous polymer. The molar ratio of the terminal alkyne to the aryl bromide is 3:1 to 1:2; The ultrasonic frequency is 20-25 kHz with automatic tracking, the output power is 450-650 W, the diameter of the amplitude transformer end is 2-10 mm, the ultrasonic pulse mode is "on for 3-7 s, off for 2-5 s", and the cumulative reaction time is 0.5-3.0 h.

2. The method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction as described in claim 1, characterized in that, The terminal alkyne monomer is any one of 1,4-diethynylbenzene, 1,3,5-triethynylbenzene, and 1,2,4,5-tetraethynylbenzene; The aryl bromide is any one of 1,4-dibromobenzene, 1,3,5-tribromobenzene, 1,2,4,5-tetrabromobenzene, and hexabromobenzene.

3. The method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction as described in claim 1, characterized in that, In step 1, the terminal alkyne is 1,4-diethynylbenzene and the aryl bromide is 1,3,5-tribromobenzene; or the terminal alkyne is 1,2,4,5-tetraethynylbenzene and the aryl bromide is 1,4-dibromobenzene; or the terminal alkyne is 1,4-diethynylbenzene and the aryl bromide is hexabromobenzene; or the terminal alkyne is 1,4-diethynylbenzene and the aryl bromide is 1,2,4,5-tetrabromobenzene; or the terminal alkyne is 1,3,5-triethynylbenzene and the aryl bromide is 1,4-dibromobenzene.

4. The method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction as described in claim 1, characterized in that, The palladium catalyst is tetra(triphenylphosphine)palladium, and the copper co-catalyst is cuprous iodide.

5. The method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction as described in claim 1, characterized in that, The volume ratio of N,N-dimethylformamide to triethylamine is 1:3 to 3:

1.

6. The method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction as described in claim 1, characterized in that, The concentration of the C-Br reaction site in the precursor solution is 0.10-0.25 mol / L.

7. The method for synthesizing alkynyl conjugated microporous polymers via ultrasound-chemically promoted Sonogashira coupling reaction as described in claim 1, characterized in that, The low-pressure filtration, washing, and vacuum drying processes involve washing with N,N-dimethylformamide, hot water, and methanol at least three times each, followed by vacuum drying at 60-120°C for 4-24 hours.

8. Application of sonochemistry-promoted Sonogashira coupling reaction for the synthesis of alkynyl conjugated microporous polymers in photocatalytic H2O2 production.

9. The application of sonicochemical-promoted Sonogashira coupling reaction to synthesize alkynyl conjugated microporous polymers in photocatalytic H2O2 production, the specific steps are as follows: S1, a suspension is obtained by adding deionized water and anhydrous ethanol to the alkynyl conjugated microporous polymer seed; S2, the suspension is ultrasonically treated with an ultrasonic cleaner to ensure full dispersion, and then high-purity oxygen is bubbled through at room temperature to make the reaction system reach oxygen saturation. S3, during the reaction process, high-purity oxygen is continuously introduced to maintain an oxygen-rich atmosphere, and photocatalytic reaction is carried out at room temperature and under light irradiation to produce H2O2.

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