A fused ring metal-covalent organic framework material, a preparation method thereof and application thereof in organic photocatalysis

Abstract

The application discloses a fused ring metal covalent organic framework material, a preparation method thereof and application of the fused ring metal covalent organic framework material in organic photocatalysis, and belongs to the technical field of photocatalysts. The preparation method of the fused ring metal covalent organic framework material is that aminophenyl units are introduced into an aldehyde group containing precursor copper-based cyclic trinuclear complex, and an organic solvent system, a first catalyst, a second catalyst, an oxidant and an oxidized styrene are added to form a heterogeneous photocatalyst. The fused ring metal covalent organic framework material can catalyze a cross-dehydrogenative coupling reaction of phenolic derivatives and phenothiazine derivatives. The application has the advantages of simple operation, mild conditions, low photocatalyst content, high yield of a multifunctional group substituted target C-N coupling product, and wide substrate applicability.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a fused-ring metal covalent organic framework material, its preparation method, and its application in organic photocatalysis. Background Technology

[0002] With the increasing prominence of global energy and environmental issues, green chemistry has become a core direction for the transformation and development of the chemical engineering field. Traditional organic synthesis processes typically rely on harsh conditions such as high temperature and high pressure, which are difficult to meet the urgent needs of sustainable development. Photocatalysis technology can directly utilize solar energy to drive chemical reactions, offering significant advantages such as mild reaction conditions, safe operation, and environmental friendliness, providing an ideal pathway for achieving green synthesis. Among them, cross-dehydrogenation coupling (CDC) reactions do not require pre-functionalization of the substrate and can directly construct new chemical bonds from two different CH bonds, highly conforming to the principles of atom economy and step economy. However, current CDC reaction systems mostly rely on homogeneous noble metal catalysts, which are not only costly but also difficult to recycle and reuse, severely restricting their large-scale application in fine chemical and pharmaceutical synthesis. Therefore, developing heterogeneous photocatalytic systems with high catalytic efficiency, excellent stability, and good recyclability has become a core problem that urgently needs to be solved in this field.

[0003] Covalent organic frameworks (COFs) are a class of crystalline porous materials composed of organic structural units linked by covalent bonds, and have shown great application potential in heterogeneous photocatalysis in recent years. COFs possess outstanding characteristics such as high specific surface area, ordered pore structure, low framework density, and pre-designable structure. Their highly ordered π-conjugated framework and tunable band structure endow the materials with excellent light-harvesting ability and charge separation efficiency, providing an ideal platform for the design of heterogeneous photocatalysts. Based on these advantages, applying COFs to photodriven cross-dehydrogenation coupling reactions holds promise for achieving efficient CN-bond construction under mild conditions, providing new ideas for developing green and sustainable heterogeneous catalytic systems.

[0004] Based on this, this patent designs and synthesizes a photocatalyst made of a fused-ring metal covalent organic framework material, and applies it to the cross-dehydrogenation coupling reaction of phenols and phenothiazine substrates to explore the practical application potential of heterogeneous photocatalysis in green organic synthesis. Summary of the Invention

[0005] The present invention aims to provide a fused-ring metal covalent organic framework material, its preparation method, and its application in organic photocatalysis. This fused-ring metal covalent organic framework material can catalyze the cross-dehydrogenation coupling reaction of phenolic derivatives and phenothiazine derivatives. The present invention is simple to operate, operates under mild conditions, requires a small amount of photocatalyst, can obtain multifunctionally substituted target CN coupling products in high yields, and has broad substrate applicability.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing a fused-ring metal covalent organic framework material, comprising:

[0008] An aldehyde-containing precursor and an amino-containing precursor were added to a heat-resistant reaction vessel, followed by the addition of an organic solvent system, a first catalyst, a second catalyst, an oxidant, and styrene oxide to obtain a mixed system. After the mixed system was fully dispersed, a sealed heating reaction was carried out. After the reaction was completed, the material was extracted and purified to obtain a fused-ring metal covalent organic framework material.

[0009] The first catalyst includes Lewis acid, and the second catalyst includes Brønsted acid.

[0010] In this invention, the aldehyde-containing precursor is further described as Cu3L3 (aldehyde trinuclear Cu precursor), wherein L is a pyrazole group;

[0011] The amino-containing precursor is N4,N4-bis(4'-amino-[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine (TBPA).

[0012] The organic solvent system is one or more of the following: o-dichlorobenzene, n-butanol, ethanol, and dimethylformamide.

[0013] The Lewis acids include copper trifluoromethanesulfonate, bismuth trifluoromethanesulfonate, scandium trifluoromethanesulfonate and / or iron trifluoromethanesulfonate;

[0014] The Brønsted acid includes acetic acid, p-toluenesulfonic acid, and / or hydrochloric acid;

[0015] The oxidizing agent includes tetrachlorobenzoquinone and / or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ).

[0016] In this invention, L is further defined as 4-aminopyrazole.

[0017] In this invention, further, the molar ratio of the aldehyde-containing precursor to the amino-containing precursor is 1:0.5-2.0; the molar ratio of the aldehyde-containing precursor to the first catalyst is 1:0.1-1.0; the molar ratio of the aldehyde-containing precursor to the second catalyst is 1:10-20; the molar ratio of the aldehyde-containing precursor to the oxidant is 1:0.5-2.0; and the molar ratio of the aldehyde-containing precursor to styrene oxide is 1:10-20.

[0018] The amount of the organic solvent system used is 10-50 mL per millimole of the organic solvent system corresponding to the aldehyde-containing precursor.

[0019] In this invention, the dispersion is further described as ultrasonic dispersion, and the dispersion time is 10-120 min;

[0020] The temperature of the sealed heating reaction is 100~180℃, and the reaction time is 24~120h;

[0021] The extraction process specifically includes: washing after the sealed heating reaction is completed, followed by Soxhlet extraction with acetone and tetrahydrofuran, with each solvent being used for 12-48 hours.

[0022] This invention also provides the preparation method described in any one of the above-mentioned methods to prepare fused-ring metal covalent organic framework materials and their application in organic photocatalysis.

[0023] Furthermore, the application specifically involves mixing phenolic derivatives with phenothiazine derivatives, fused-ring metal covalent organic framework materials, potassium carbonate, and organic solvents. Under an oxygen atmosphere, white LED irradiation, and continuous stirring, the system is kept at room temperature by a fan for heat dissipation to obtain the target product.

[0024] Further, the molar ratio of the phenolic derivative to the phenothiazine derivative is 2:1-4:1; the molar ratio of the phenolic derivative to the fused-ring metal covalent organic framework material is 1:0.005-1:0.0025; and the molar ratio of the phenolic derivative to potassium carbonate is 2:1-4:1.

[0025] Furthermore, the molar ratio of the phenolic derivative to the volume ratio of the organic solvent is 2 mmol: 5-10 mL.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) This invention uses aldehyde-containing precursors and amino-containing precursors as raw materials to construct COF powder through solvothermal condensation reaction, and introduces a Lewis acid / Brønsted acid dual catalytic system and styrene oxide, etc., to anchor copper metal in the COF framework in a cyclic coordination form through an in-situ redox strategy. This method has mild reaction conditions, high yield, and overcomes the defects of uneven metal loading and easy agglomeration in traditional post-modification methods.

[0028] (2) The fused-ring metal covalent organic framework material prepared in this invention significantly enhances visible light absorption and photogenerated carrier separation efficiency due to the introduction of a copper metal center to form a donor-acceptor (DA) structure. Simultaneously, the synergistic confinement effect of the copper ring structure and the COF channels endows the material with excellent reactive oxygen species (ROS) generation capabilities, making its yield and selectivity for driving the CDC reaction under light significantly superior to non-metallic COF or traditional copper salt catalysts. Furthermore, it exhibits good compatibility when different substituents are introduced onto the phenothiazine ring. This method uses only methanol as a green solvent and potassium carbonate as a weak base, requiring no high temperature, strong oxidants, or noble metals; the reaction conditions are mild and the operation is simple.

[0029] In summary, this fused-ring metal covalent organic framework material exhibits excellent catalytic performance and substrate versatility in visible light-driven cross-dehydrogenation coupling reactions. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the fused ring metal covalent organic framework material of the present invention;

[0031] Figure 2 The image shows the PXRD pattern of the fused-ring metal covalent organic framework material of this invention.

[0032] Figure 3 The infrared spectrum of the fused-ring metal covalent organic framework material of this invention is shown below.

[0033] Figure 4 This is a scanning electron microscope (SEM) image of the fused-ring metal covalent organic framework material of the present invention.

[0034] Figure 5 The 1H NMR spectrum of 3aa prepared in Application Example 1 of this invention;

[0035] Figure 6 The 1H NMR spectrum of 3ba prepared in Application Example 2 of this invention;

[0036] Figure 7 The 1H NMR spectrum of 3ca prepared in Example 3 of this invention;

[0037] Figure 8 The 1H NMR spectrum of 3ab prepared in Example 4 of this invention;

[0038] Figure 9 The 1H NMR spectrum of 3ac prepared in Example 5 of this invention;

[0039] Figure 10 The 1H NMR spectrum of 3ad prepared in Example 6 of this invention is shown. Detailed Implementation

[0040] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0041] The aldehyde-based trinuclear Cu precursor described in this embodiment has the following structural formula: .

[0042] The N4,N4-bis(4'-amino-[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine used has the following structural formula: .

[0043] Example 1

[0044] A method for preparing a fused-ring metal covalent organic framework material includes the following steps:

[0045] Weigh out 76.8 mg of aldehyde trinuclear Cu precursor (1.6 × 10⁻⁶ mg). -4 mol) and 83 mg TBPA (1.6 × 10⁻⁶) -4 Add 1 mol of styrene to a heat-resistant glass tube, along with 4 mL of n-butanol and 4 mL of o-dichlorobenzene. Disperse under ultrasonic conditions for 30 min. Then add 0.225 mL of styrene oxide, 18 mg of DDQ, 30 mg of scandium trifluoromethanesulfonate, and 0.45 mL of 6 mol / L acetic acid aqueous solution, and continue ultrasonic dispersion for 30 min. Seal the reaction tube and heat to 120 °C for 3 days. After the reaction, allow the reaction tube to cool naturally to room temperature. Separate the obtained reaction product by vacuum filtration, and then purify it by Soxhlet extraction with acetone and tetrahydrofuran, respectively, for 24 h each time. After extraction, separate the solid and dry it in a vacuum drying oven at 120 °C for 12 h to obtain COF powder material, the structure of which is shown below. Figure 1 As shown.

[0046] Figure 2 The image shows the X-ray powder diffraction (PXRD) pattern of the fused-ring metal covalent organic framework material prepared in Example 1 of this invention. The PXRD pattern shows obvious diffraction peaks in the low-angle region, indicating that the material has high crystallinity. Comparison shows that the peak shape and position of the experimental and refined values ​​match well, indicating that the synthesized fused-ring metal covalent organic framework material is the target product.

[0047] Figure 3 This is the Fourier transform infrared spectrum of the fused-ring metal-covalent organic framework material prepared in Example 1 of this invention. The test results show that the characteristic vibrational peaks of the aldehyde and amino groups are significantly weakened or even disappear, and at 1597 cm⁻¹... -1A new absorption peak was observed, which is attributed to the stretching vibration characteristics of the imine bond (C=N), confirming the successful formation of the imine bond and the successful construction of the expected fused ring metal covalent organic framework material.

[0048] Figure 4 This is a scanning electron microscope (SEM) image of the fused-ring metal covalent organic framework material prepared in Example 1 of this invention. The results show that the prepared fused-ring metal covalent organic framework material exhibits a stacked spherical nanostructure.

[0049] The applicant applies fused-ring metal covalent organic framework materials to organic photocatalysis, specifically preparing CN-coupled products via photocatalytic cross-dehydrogenation coupling reactions. The reaction process is as follows:

[0050]

[0051] In compound 1, R1 is methoxy, phenoxy, or propoxy; in compound 2, R2 is hydrogen, chlorine, trifluoromethyl, or methoxy.

[0052] Application Example 1

[0053]

[0054] 4-Methoxyphenol 1a (2 mmol), phenothiazine 2a (0.5 mmol), potassium carbonate (0.5 mmol), fused-ring metal covalent organic framework material (5.3 mg), and methanol (10 mL) were added to a glass tube (15 cm long, 20 cm in diameter) containing a stir bar and sealed with a rubber stopper. After sonication for 30 minutes, the tube was circulated three times under vacuum with oxygen. The photocatalytic reaction was carried out for 1 hour under an oxygen atmosphere, irradiated by a white LED (40 W), and with continuous stirring, while maintaining room temperature through a fan for heat dissipation. The crude product was obtained by TLC, filtration, and vacuum concentration. The crude product was then separated by silica gel column chromatography to obtain the target CN-coupled product, denoted as 3aa, with a yield of 97%.

[0055] The 1H NMR spectrum of the 3aa prepared in Example 1 is as follows: Figure 5 The NMR data are as follows: 1H NMR (400 MHz, DMSO) δ 9.46 (s, 1H), 7.06 (d, J = 8.9 Hz, 1H), 7.02 - 6.94 (m, 3H), 6.90 (ddd, J = 8.3, 7.3, 1.6 Hz, 2H), 6.84 - 6.74 (m, 3H), 6.08 (dd, J = 8.2, 1.2Hz, 2H), 3.70 (s, 3H).

[0056] Application Example 2

[0057]

[0058] In Application Example 1, 4-methoxyphenol 1a was replaced with 4-phenoxyphenol 1b, and everything else was the same as in Application Example 1. The target CN-coupled product was obtained, denoted as 3ba, with a yield of 75%.

[0059] The 1H NMR spectrum of 3ba prepared in Example 2 is as follows: Figure 6 The NMR data are as follows: 1H NMR (400 MHz, DMSO) δ 9.92 (s, 1H), 7.40 - 7.30 (m, 2H), 7.20 - 7.04 (m, 3H), 7.02 - 6.87 (m, 7H), 6.81 (td, J = 7.4, 1.2 Hz, 2H), 6.14 (dd, J = 8.2, 1.2 Hz, 2H).

[0060] Application Example 3

[0061]

[0062] In Application Example 1, 4-methoxyphenol 1a was replaced with 4-propoxyphenol 1c, and everything else was the same as in Application Example 1. The target CN-coupled product was obtained, denoted as 3ca, with a yield of 96%.

[0063] The 1H NMR spectrum of the 3ca prepared in Example 3 is as follows: Figure 7 The NMR data are as follows: 1H NMR (400 MHz, DMSO) δ 9.44 (s, 1H), 7.04 (d, J = 8.9 Hz, 1H), 6.97 (ddd, J = 8.7, 5.7, 2.3Hz, 3H), 6.90 (ddd, J = 8.4, 7.4, 1.7 Hz, 2H), 6.81 - 6.76 (m, 3H), 6.08 (dd, J = 8.2, 1.2 Hz, 2H), 3.84 (t, J = 6.5 Hz, 2H), 1.67 (q, J = 7.0 Hz, 2H), 0.94 (t, J = 7.4 Hz, 3H).

[0064] Application Example 4

[0065]

[0066] In Application Example 1, phenothiazine 2a was replaced with 2-chlorophenothiazine 2b, and everything else was the same as in Application Example 1. The target CN coupling product was obtained, denoted as 3ab, with a yield of 97%.

[0067] The 1H NMR spectrum of 3ab prepared in Example 4 is as follows: Figure 8 The NMR data are as follows: 1H NMR (400 MHz, DMSO) δ 9.59 (s, 1H), 7.08 (d, J = 8.9 Hz, 1H), 7.05 - 6.98 (m, 3H), 6.93 (ddd, J = 8.4, 7.4, 1.6 Hz, 1H), 6.88 - 6.79 (m, 3H), 6.08 (dd, J = 8.2, 1.2Hz, 1H), 5.99 (d, J = 2.2 Hz, 1H), 3.71 (s, 3H).

[0068] Application Example 5

[0069]

[0070] In Application Example 1, phenothiazine 2a was replaced with 2-trifluoromethylphenothiazine 2c, and everything else was the same as in Application Example 1. The target CN coupling product was obtained, denoted as 3ac, with a yield of 90%.

[0071] The 1H NMR spectrum of the 3ac prepared in Example 5 is as follows: Figure 9 The NMR data are as follows: 1H NMR (400 MHz, DMSO) δ 9.64 (s, 1H), 7.24 - 7.19 (m, 1H), 7.15 - 7.06 (m, 2H), 7.06 - 6.99 (m, 2H), 6.98 - 6.91 (m, 1H), 6.89 - 6.81 (m, 2H), 6.23 (d, J = 1.8 Hz, 1H), 6.07 (dd, J = 8.3, 1.3 Hz, 1H), 3.70 (s, 3H).

[0072] Application Example 6

[0073]

[0074] In Application Example 1, phenothiazine 2a was replaced with 2-methoxyphenothiazine 2d, and everything else was the same as in Application Example 1. The target CN coupling product was obtained, denoted as 3ad, with a yield of 94%.

[0075] The 1H NMR spectrum of the 3ad prepared in Example 6 is as follows: Figure 10The NMR data are as follows: 1H NMR (400 MHz, DMSO) δ 9.46 (s, 1H), 7.06 (d, J = 8.9 Hz, 1H), 7.02 - 6.96 (m, 2H), 6.95 -6.86 (m, 2H), 6.82 - 6.75 (m, 2H), 6.45 (dd, J = 8.4, 2.6 Hz, 1H), 6.09 (dd, J = 8.2, 1.2 Hz, 1H), 5.64 (d, J = 2.6 Hz, 1H), 3.70 (s, 3H), 3.55 (s, 3H).

[0076] The above application examples demonstrate that the fused-ring metal-covalent organic framework material prepared in this invention exhibits excellent catalytic activity in photocatalytic cross-dehydrogenation coupling amination reactions. This reaction, carried out at room temperature, under 40 W white light, and in an oxygen atmosphere at ambient pressure, can convert various phenolic derivatives and phenothiazine derivatives into the target CN coupling product in yields of 75%–97%. Regarding substrate adaptability, the reaction proceeds smoothly when the phenol ring contains electron-donating groups (such as methoxy, propoxy, and phenoxy). Furthermore, it also exhibits good compatibility when different substituents are introduced onto the phenothiazine ring. This method uses only methanol as a green solvent and potassium carbonate as a weak base, requiring no high temperature, strong oxidants, or noble metals; the reaction conditions are mild and the operation is simple. In summary, this fused-ring metal-covalent organic framework material demonstrates good catalytic performance and substrate versatility in visible light-driven cross-dehydrogenation coupling reactions.

[0077] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent substitutions, modifications, and improvements 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 method for preparing a fused-ring metal covalent organic framework material, characterized in that, include: An aldehyde-containing precursor and an amino-containing precursor were added to a heat-resistant reaction vessel, followed by the addition of an organic solvent system, a first catalyst, a second catalyst, an oxidant, and styrene oxide to obtain a mixed system. After the mixed system was fully dispersed, a sealed heating reaction was carried out. After the reaction was completed, the material was extracted and purified to obtain a fused-ring metal covalent organic framework material. The first catalyst includes Lewis acid, and the second catalyst includes Brønsted acid.

2. The method for preparing the fused-ring metal covalent organic framework material according to claim 1, characterized in that, The aldehyde-containing precursor is Cu3L3, where L is a pyrazole group; The amino-containing precursor is N4,N4-bis(4'-amino-[1,1'-biphenyl]-4-yl)-[1,1'-biphenyl]-4,4'-diamine; The organic solvent system is one or more of the following: o-dichlorobenzene, n-butanol, ethanol, and dimethylformamide. The Lewis acids include copper trifluoromethanesulfonate, bismuth trifluoromethanesulfonate, scandium trifluoromethanesulfonate and / or iron trifluoromethanesulfonate; The Brønsted acid includes acetic acid, p-toluenesulfonic acid, and / or hydrochloric acid; The oxidant includes tetrachlorobenzoquinone and / or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.

3. The method for preparing the fused-ring metal covalent organic framework material according to claim 2, characterized in that, The L is 4-aminopyrazole.

4. The method for preparing the fused-ring metal covalent organic framework material according to claim 1, characterized in that, The molar ratio of the aldehyde-containing precursor to the amino-containing precursor is 1:0.5-2.0; the molar ratio of the aldehyde-containing precursor to the first catalyst is 1:0.1-1.0; the molar ratio of the aldehyde-containing precursor to the second catalyst is 1:10-20; the molar ratio of the aldehyde-containing precursor to the oxidant is 1:0.5-2.0; and the molar ratio of the aldehyde-containing precursor to styrene oxide is 1:10-20. The amount of the organic solvent system used is 10-50 mL per millimole of the organic solvent system corresponding to the aldehyde-containing precursor.

5. The method for preparing the fused-ring metal covalent organic framework material according to claim 1, characterized in that, The dispersion is performed by ultrasonic dispersion, and the dispersion time is 10~120 min; The temperature of the sealed heating reaction is 100~180℃, and the reaction time is 24~120h; The extraction process specifically includes: washing after the sealed heating reaction is completed, followed by Soxhlet extraction with acetone and tetrahydrofuran, with each solvent being used for 12-48 hours.

6. A fused-ring metal covalent organic framework material is prepared by the preparation method according to any one of claims 1-5.

7. The application of the fused-ring metal covalent organic framework material according to claim 6 in organic photocatalysis.

8. The application according to claim 7, characterized in that, The specific application involves mixing phenolic derivatives with phenothiazine derivatives, fused-ring metal covalent organic framework materials, potassium carbonate, and organic solvents. Under an oxygen atmosphere, white LED irradiation, and continuous stirring, the system is kept at room temperature by a fan for heat dissipation to carry out a photocatalytic reaction and obtain the target product.

9. The application according to claim 8, characterized in that, The molar ratio of the phenolic derivative to the phenothiazine derivative is 2:1-4:1; the molar ratio of the phenolic derivative to the fused-ring metal covalent organic framework material is 1:0.005-1:0.0025; and the molar ratio of the phenolic derivative to potassium carbonate is 2:1-4:

1.

10. The application according to claim 8, characterized in that, The molar ratio of the phenolic derivative to the volume of the organic solvent is 2 mmol: 5-10 mL.

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