A sulfur-containing tridentate compound, its preparation method and application

Abstract

This invention provides a sulfur-containing tridentate compound, its preparation method, and its application, relating to the fields of supramolecular chemistry and organic synthesis. This invention designs different tridentate frameworks and combines them with sulfur-containing compounds to synthesize sulfur-containing tridentate compounds. These compounds, combined with CB[8], construct tridentate alkyl assemblies. The intermolecular voids formed by the aggregation of these assemblies stabilize the gold nanoparticles, limiting their size. Sulfur-containing tridentate compounds contain N and S atoms. Since nitrogen atoms serve as nucleation sites for gold, and sulfur atoms form stable Au-S bonds with gold, it is easier to prepare gold nanoparticles with uniform size. The uniformly sized gold nanoparticles prepared by this invention exhibit higher catalytic activity in catalytic applications.

Description

Technical Field

[0001] This invention relates to the fields of supramolecular chemistry and organic synthesis, and more specifically, to methods for synthesizing various sulfur-containing tridentate compounds. Background Technology

[0002] In 2019, Ashish Verma et al. analyzed the crystal structure of crypt ethers containing bispyrazole groups and found that the length of the crypt ether cage was about 2 nm, while the average size of PdNPs was 2.24 nm. This indicates that about 5 or more crypt ether molecules aggregate to form intermolecular vacancies, thereby stabilizing nanoparticles. (Ashish Verma, Kapil Tomar, Parimal K. Bharadwaj. Nanosized Bispyrazole-Based Cryptand-Stabilized Palladium (0)Nanoparticles: A Reusable Heterogeneous Catalyst for the Suzuki–Miyaura Coupling Reaction in Water. Inorg. Chem. 2019, 58, 2, 1003–1006.) In 2021, Zhao Yingjie et al. designed a tridentate compound with one nitrogen atom as the core and three 4-phenylpyridines as arms. The tridentate compound combined with CB[8] to form a tridentate alkyl assembly for cell imaging. (Hui Liu, Min Lin, Yu Cui, et al. "Single-crystal structures of cucurbituril-based supramolecular host–guest complexes for bioimaging". Chem. Commun. 2021, 57, 10190-10193.) The tridentate compounds designed by Zhao Yingjie et al. are rigid molecules. The tridentate compounds combine with CB[8] to construct tridentate alkane assemblies. The size of the intermolecular cavities formed by the aggregation of multiple assemblies is too small to be used to stabilize nanoparticles. Based on the above background technology and literature review, this invention designs different tridentate frameworks and prepares sulfur-containing tridentate compounds. The sulfur-containing tridentate compounds combine with CB[8] to construct tridentate alkane assemblies. The sulfur-containing tridentate compounds designed and prepared in this invention

[0003] Tridentate compounds are flexible molecules. Sulfur-containing tridentate compounds combine with CB[8] to construct tridentate alkyl assemblies. The size of the intermolecular vacancies formed by the aggregation of the assemblies is suitable and can be used to stabilize gold nanoparticles and control the size of gold nanoparticles. Sulfur-containing tridentate compounds contain N and S atoms. Since nitrogen atoms serve as nucleation sites for gold and sulfur atoms form stable Au-S bonds with gold, it is easier to prepare gold nanoparticles with uniform size. Summary of the Invention

[0004] The purpose of this invention is to propose different tridentate frameworks, synthesize sulfur-containing tridentate compounds, and then combine them with CB[8] to construct tridentate alkyl assemblies. The intermolecular holes formed by the aggregation of the assemblies stabilize the gold nanoparticles, thus preparing more uniform gold nanoparticles. The sulfur-containing tridentate compounds synthesized in this invention introduce N and S atoms. Nitrogen atoms can serve as nucleation sites for gold, and sulfur atoms can form Au-S bonds with gold, making it easier to prepare gold nanoparticles with uniform size. At the same time, the preparation method of this type of sulfur-containing tridentate compound is simple. The uniform gold nanoparticles prepared by this invention have higher catalytic activity in catalytic applications.

[0005] To solve the technical problem of this invention, the proposed technical solution is as follows: This invention provides different three-tooth skeletons, the structural formulas of which are as follows:

[0006]

[0007] In the formula, R represents a simple sulfur-containing compound:

[0008] R1: R2: .

[0009] Preferably, the compound is any one of the following structural formulas: .

[0010] The preparation methods for the sulfur-containing tridentate compounds, and the reaction routes for different tridentate framework preparation methods are as follows:

[0011] Skeleton A:

[0012]

[0013] Skeleton B:

[0014] Preferably, the reaction route for preparing the sulfur-containing tridentate compound is as follows:

[0015] Compound 1a:

[0016]

[0017] Compound 1b:

[0018]

[0019] Compound 1c:

[0020] .

[0021] The application of the sulfur-containing tridentate compound in the preparation of nanoparticles.

[0022] The application of the sulfur-containing tridentate compound involves combining the sulfur-containing tridentate compound with CB[8] to construct a tridentate alkyl assembly. The intermolecular voids formed by the aggregation of the assembly stabilize the gold nanoparticles, thus preparing relatively uniform gold nanoparticles. The sulfur-containing tridentate compound contains N and S atoms. Since the nitrogen atom serves as the nucleation site for gold, and the sulfur atom forms a stable Au-S bond with gold, it is easier to prepare gold nanoparticles with uniform size.

[0023] This invention provides synthetic routes for different tridentate skeletons, as follows:

[0024] Framework A: Under nitrogen protection in an ice-water bath, 1,3,5-tris(4-methylphenyl)benzene, N-bromosuccinimide, and benzoyl peroxide were added, followed by the addition of carbon tetrachloride to remove oxygen during freezing. The mixture was then heated to 90°C. o The mixture was stirred under reflux at C overnight. After the reaction was complete, it was cooled, filtered, and dried under vacuum to obtain a white, light solid. Reaction formula:

[0025]

[0026] Framework B: Add 4-cyanobenzyl bromide under nitrogen protection in an ice-water bath, then add trifluoromethanesulfonic acid dropwise, slowly heating to room temperature while stirring. After the reaction is complete, add ammonia water to the precipitate formed in the ice-water mixture to neutralize, filter, wash, and vacuum dry to obtain a white powder; Reaction formula:

[0027]

[0028] This type of tridentate framework can be combined with sulfur-containing compounds to obtain different sulfur-containing tridentate compounds. Furthermore, this type of compound can be further combined with CB[8] to construct tridentate alkyl assemblies. The intermolecular holes formed by the aggregation of the assemblies stabilize the gold nanoparticles, thus preparing relatively uniform gold nanoparticles.

[0029] Beneficial effects:

[0030] This invention provides methods for preparing different tridentate frameworks, and the obtained tridentate frameworks can be combined with sulfur-containing compounds to prepare different sulfur-containing tridentate compounds. The sulfur-containing tridentate compounds prepared by this invention are flexible molecules. The sulfur-containing tridentate compounds and CB[8] construct tridentate alkyl assemblies. The assemblies aggregate to form intermolecular vacancies of suitable size, which can be used to stabilize gold nanoparticles and control the size of gold nanoparticles. In addition, the sulfur-containing tridentate compounds contain N and S atoms. Since nitrogen atoms serve as nucleation sites for gold and sulfur atoms form stable Au-S bonds with gold, it is easier to prepare gold nanoparticles with uniform size. The gold nanoparticles with uniform size prepared by this invention have higher catalytic activity in catalytic applications.

[0031] TEM results as follows Figure 5 As shown, the aggregates of the tridentate compound 1b and CB[8] assembly are clearly visible as a blocky structure. Meanwhile, the sample was characterized by scanning transmission electron microscopy (STEM), and the results are shown in […]. Figure 6 . Figure 6 This indicates that gold nanoparticles with a size of about 2 nm exist at the edge of the bulk structure. Attached Figure Description

[0032] Figure 1 The 1H NMR spectrum of the tridentate compound 1a

[0033] Figure 2 The 1H NMR spectrum of the tridentate compound 1b

[0034] Figure 3 The 1H NMR spectrum of the tridentate compound 1c

[0035] Figure 4 The 1H NMR spectrum of the tridentate compound 1b-CB[8]

[0036] Figure 5 TEM image of gold nanoparticles prepared in situ based on the tridentate compound 1b and CB[8] in a tridentate alkyl assembly.

[0037] Figure 6 STEM image of gold nanoparticles prepared in situ from a tridentate compound 1b and CB[8] alkyl tridentate assembly. Detailed Implementation

[0038] Example 1

[0039] The inventors designed different tridentate frameworks, combined them with sulfur-containing compounds, and then synthesized different sulfur-containing tridentate compounds. These sulfur-containing tridentate compounds combined with CB[8] to construct tridentate alkyl assemblies. The intermolecular vacancies formed by the aggregation of the assemblies can be used to stabilize gold nanoparticles and control the size of gold nanoparticles.

[0040] Specific preparation methods and reaction formulas for different skeletons:

[0041] Skeleton A:

[0042] Weigh 1,3,5-tris(4-methylphenyl)benzene (1000 mg, 2.86 mmol, 1.00 equiv.), N-bromosuccinimide (1680 mg, 9.44 mmol, 3.30 equiv.), and benzoyl peroxide (69 mg, 0.28 mmol, 0.10 equiv.) into a two-necked reaction flask, and purge the flask three times with nitrogen. Then, add 30 mL of carbon tetrachloride that has been pre-deoxygenated under liquid nitrogen conditions. After the addition is complete, heat the reaction mixture to 90°C. o C. Reflux and stir overnight. During the reaction, monitor the progress by TLC. After the reaction is complete, cool to room temperature, filter, wash the filter cake with acetone, and dry under vacuum to give a white, light solid (136 mg, 8%).

[0043] 1 H NMR (400 MHz, CDCl3) δ 7.75 (s, 3H), 7.66 (d, J = 8.0 Hz, 6H), 7.51 (d, J = 8.0 Hz, 6H), 4.58 (s, 6H).

[0044] 13 C NMR (75 MHz, CDCl3) δ 142.25, 141.46, 137.72, 130.15, 128.26,125.76, 33.80.

[0045]

[0046] Skeleton B:

[0047] Weigh 200 mg (1.02 mmol, 1.00 equiv.) of 4-cyanobenzyl bromide into a Shrek flask, purge with nitrogen, and heat at 0°C. o Trifluoromethanesulfonic acid (459.3 mg, 3.06 mmol, 3.00 equiv.) was added dropwise at C, and the mixture was slowly heated to room temperature under natural conditions and stirred for 12 h. After the reaction was completed by TLC, the precipitate formed in the mixture in ice water was added to ammonia water for neutralization. The precipitate was filtered, the filter cake was washed with acetone, and vacuum dried to obtain a white powder (170 mg, 85%).

[0048] 1H NMR (400 MHz, CDCl3) δ 8.73 (d, J = 7.7 Hz, 6H), 7.60 (d, J = 7.1Hz, 6H), 4.60 (s, 6H).

[0049] 13 C NMR (75 MHz, CDCl3) δ 171.52, 142.75, 136.52, 129.98, 129.84,33.12.

[0050] Preparation methods and reaction formulas of sulfur-containing compounds:

[0051]

[0052] Compound R1: 4-Methylthiophenylboronic acid (984 mg, 5.86 mmol, 1.00 equiv.), 4-iodopyridine (1.20 g, 5.86 mmol, 1.00 equiv.), potassium hydroxide (1.49 g, 29.90 mmol, 5.10 equiv.), (Bu)4NBr (246 mg, 0.76 mmol, 0.13 equiv.), and Pd(PPh3)4 (250 mg, 0.22 mmol, 0.037 equiv.) were weighed into a two-necked flask. A mixed solution of ultra-dry N,N-dimethylformamide and 1,2-dimethoxyethane (DMF / 1,2-Dimethoxyethane = 5 / 4, bubbled to remove oxygen) was added. The container was sealed and heated to 80°C with stirring for 48 h. After the reaction was completed by TLC, the reactants were cooled to room temperature and transferred to 40 mL of dichloromethane. The crude product was washed with water and brine, the organic layer was dried with anhydrous sodium sulfate, filtered, the solvent was removed by vacuum evaporation using a rotary evaporator, and a white, bright powder (969 mg, 82%) was obtained by silica gel column chromatography (PE:EA=2:1).

[0053] 1 H NMR (400 MHz, CDCl3) δ 8.67 (d, J = 5.8 Hz, 2H), 7.73 (d, J = 5.4Hz, 2H), 7.66 – 7.59 (d, 2H), 7.38 (d, J = 6.3 Hz, 2H), 2.55 (s, 3H).

[0054] 13 C NMR (75 MHz, CDCl3) δ 150.25, 127.18, 126.56, 121.11, 15.38.

[0055] Compound R2: The double-necked flask and condenser were first placed in an oven for 20 min, then baked under negative pressure for 2 min, and cooled. Compound R1 (140 mg, 0.69 mmol, 1.00 equiv.) and t-BuSNa powder (220 mg, 1.96 mmol, 2.82 equiv.) were weighed into the double-necked flask. 10 mL of N,N-dimethylformamide (DMF, bubbled to remove oxygen) was added, and the reaction mixture was stirred vigorously. The mixture was then placed in an oil bath preheated to 170°C and stirred for 48 h. After the reaction was detected by TLC, the reaction mixture was cooled to room temperature and then quickly poured onto 45 g of crushed ice, stirred until the ice was completely melted. The pH was adjusted to 7 using hydrochloric acid aqueous solution, and the mixture was extracted with dichloromethane. The organic phase was collected, washed several times with water to remove DMF, dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The solution was obtained by silica gel column chromatography (SiO2, PE:EA = 2:1) to give a pale white powder (32 mg, 25%).

[0056] 1 H NMR (400 MHz, CDCl3) δ 8.69 – 8.63 (m, 2H), 7.70 (d, J = 8.6 Hz, 2H), 7.64 – 7.57 (m, 4H), 3.49 (s, 1H).

[0057] Preparation methods and reaction formulas of different sulfur-containing tridentate compounds:

[0058]

[0059] Compound 1a:

[0060] Weigh skeleton A (62 mg, 0.32 mmol, 6.00 equiv.) and R1 (30 mg, 0.05 mmol, 1.00 equiv.) into a two-necked flask, purge with nitrogen, and add 3 mL of acetonitrile under nitrogen atmosphere. o Refluxed at C for 14 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and washed with dichloromethane to obtain a yellow powder (45 mg, 70%).

[0061] 1H NMR (400 MHz, DMSO-d6) δ 9.23 (d, J = 6.7 Hz, 6H), 8.54 (d, J = 6.7Hz, 6H), 8.04 (d, J = 8.4 Hz, 6H), 7.94 (d, J = 8.1 Hz, 6H), 7.91 (s, 3H), 7.72 (d, J = 8.2 Hz, 6H), 7.49 (d, J = 8.5 Hz, 6H), 5.85 (s, 6H), 3.40 (s, 9H).

[0062] 13 C NMR (75 MHz, DMSO-d6) δ 154.31, 145.00, 144.59, 140.85, 140.73,134.11, 129.45, 129.06, 128.51, 127.99, 125.94, 124.90, 124.03, 61.84, 13.98.

[0063] Compound 1b:

[0064]

[0065] Weigh backbone B (51.4 mg, 0.26 mmol, 5.00 equiv.) and monomer R1 (30 mg, 0.051 mmol, 1.00 equiv.) into a two-necked flask, purge with nitrogen, and add 3 mL of acetonitrile under nitrogen atmosphere. o Refluxed at C for 14 h. After the reaction was completed by TLC, the mixture was cooled to room temperature, filtered, and washed with dichloromethane to obtain a yellow powder (58 mg, 96%).

[0066] 1 H NMR (400 MHz, DMSO-d6) δ 9.22 (d, J = 6.6 Hz, 6H), 8.77 (d, J = 8.2Hz, 6H), 8.57 (d, J = 6.8 Hz, 6H), 8.09 – 8.03 (m, 6H), 7.80 (d, J = 8.2 Hz, 6H), 7.49 (d, J = 8.5 Hz, 6H), 5.96 (s, 6H), 2.57 (s, 9H).

[0067] 13C NMR (75 MHz, DMSO-d6) δ 170.65, 154.41, 145.06, 144.77, 139.36,135.89, 129.49, 129.33, 128.97, 125.93, 124.01, 61.66, 13.98.

[0068] Compound 1c:

[0069]

[0070] Weigh skeleton B (30 mg, 0.16 mmol, 10.00 equiv.) and R2 (9.4 mg, 0.016 mmol, 1.00 equiv.) into a two-necked flask, purge with nitrogen, and add 3 mL of acetonitrile under nitrogen atmosphere. o Refluxed at C for 14 h. After the reaction was completed by TLC, the mixture was cooled to room temperature, filtered, and washed with dichloromethane to obtain a yellow powder (8 mg, 43%).

[0071] 1 H NMR (400 MHz, DMSO-d6) δ 9.26 (d, J = 5.9 Hz, 6H), 8.77 (d, J = 7.8Hz, 6H), 8.57 (d, J = 6.1 Hz, 6H), 8.13 – 8.07 (m, 6H), 7.86 – 7.77 (m, 12H), 5.98 (s, 6H), 5.76 (s, 3H).

[0072] Applications of the sulfur-containing tridentate compound designed in this invention:

[0073] This type of sulfur-containing tridentate compound can combine with CB[8] to construct tridentate alkyl assemblies. The intermolecular vacancies formed by the aggregation of the assemblies can be used to stabilize gold nanoparticles, thereby controlling the size of gold nanoparticles.

[0074] The experimental steps for in-situ preparation of gold nanoparticles based on the cavity between compound 1b and CB[8] trigorane assembly and their characterization by transmission electron microscopy (TEM) are as follows:

[0075] The method for preparing gold nanoparticles is as follows:

[0076] Weigh 1.2 mg (0.001 mmol) of tridentate compound 1b and CB[8] (2 mg, 0.0015 mmol) into a 1.5 mL gas flask, add 1 mL of deionized water, and 80 mL of gas flask. oThe mixture was stirred at C for 4 h. Then, the reaction solution was cooled to room temperature, and 20 μL of NaAuCl4 aqueous solution (0.0005 mmol) was added. The mixture was then stirred vigorously overnight at room temperature. Afterward, 20 μL of NaBH4 solution (0.000125 mmol) was added, and the mixture was stirred vigorously for another 2 minutes. Finally, the reaction solution was centrifuged at 12000 r for 5 minutes.

[0077] 1 H NMR (400 MHz, D2O) δ 8.50 (s, 4H), 8.36 (d, J = 8.2 Hz, 4H), 7.61(s, 4H), 7.56 (d, J = 8.2 Hz, 4H), 6.70 (d, J = 8.3 Hz, 4H), 6.33 (d, J = 8.1Hz, 4H), 5.71 – 5.57 (m, 9H), 5.57 – 5.43 (m, 9H), 5.27 (d, J = 3.3 Hz, 19H), 4.90 (s, 3H), 3.97 (t, J = 13.3 Hz, 19H), 2.05 (d, J = 3.4 Hz, 6H).

[0078] The transmission electron microscopy (TEM) characterization results are as follows:

[0079] TEM results as follows Figure 5 As shown, the aggregates of the tridentate compound 1b and CB[8] assembly are clearly visible as a blocky structure. Meanwhile, the sample was characterized by scanning transmission electron microscopy (STEM), and the results are shown in […]. Figure 6 . Figure 6 This indicates that gold nanoparticles with a size of about 2 nm exist at the edge of the bulk structure.

[0080] Gold nanoparticles have a wide range of applications. In medicine, they demonstrate excellent drug delivery capabilities, precisely transporting therapeutic payloads to designated targets. In biosensors, colorimetric probes are crucial in colorimetric assays, primarily affecting detection sensitivity. Currently, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) have been developed for the colorimetric detection of target analytes. Among these probes, gold nanoparticles exhibit significant advantages due to their unique properties. In catalysis, gold nanoparticles can enhance reaction rates and provide higher selectivity.

[0081] This invention designs different tridentate frameworks to prepare different sulfur-containing tridentate compounds. These compounds combine with CB[8] to construct tridentate alkyl assemblies. The intermolecular holes formed by the aggregation of the assemblies stabilize the gold nanoparticles and limit their size. The sulfur-containing tridentate compounds contain N and S atoms. Since nitrogen atoms serve as nucleation sites for gold and sulfur atoms form stable Au-S bonds with gold, it is easier to prepare gold nanoparticles with uniform size. The uniformly sized gold nanoparticles prepared by this invention have higher catalytic activity in catalytic applications.

[0082] The present invention is not limited to the specific technical solutions described in the above embodiments. All technical solutions formed by equivalent substitutions are within the scope of protection claimed by the present invention.

Claims

1. A sulfur-containing tridentate compound, characterized in that: The compound is any one of the following structural formulas: Compound 1a Compound 1b Compound 1c 2. The method for preparing the sulfur-containing tridentate compound according to claim 1, characterized in that: The reaction routes for different tridentate framework preparation methods are as follows: Skeleton A: Skeleton B: The reaction route for preparing the sulfur-containing tridentate compound is as follows: Compound 1a: Compound 1b: Compound 1c:

3. The application of the sulfur-containing tridentate compound according to claim 1 in the preparation of gold nanoparticles.

4. The application of the sulfur-containing tridentate compound according to claim 3 in the preparation of gold nanoparticles, characterized in that: Sulfur-containing tridentate compounds and CB[8] construct tridentate alkyl assemblies. The aggregation of the assemblies forms intermolecular vacancies, which can be used to stabilize gold nanoparticles and control the size of gold nanoparticles. Sulfur-containing tridentate compounds contain N and S atoms. Since nitrogen atoms serve as nucleation sites for gold and sulfur atoms form stable Au-S bonds with gold, it is easier to prepare nanoparticles with uniform size.

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