Sulfur-containing tridentate compound as well as preparation method and application thereof

Abstract

The invention provides a sulfur-containing tridentate compound as well as a preparation method and application thereof, and relates to the technical field of supramolecular chemistry and organic synthesis. According to the invention, different tridentate skeletons are designed and combined with a sulfur-containing compound to synthesize the sulfur-containing tridentate compound. The compound is combined with CB [8] to construct a trigerane assembly, and the size of the gold nanoparticles is limited by stabilizing the gold nanoparticles through intermolecular holes formed by aggregation of the assembly. The sulfur-containing tridentate compound contains N and S atoms, the nitrogen atom is used as a nucleation site of gold, and the sulfur atom and the gold form a stable Au-S bond, so that the gold nanoparticles with uniform size are easier to prepare. The gold nanoparticles with uniform size prepared by the method have higher catalytic activity in the aspect of catalytic application.

Description

Technical Field

[0001] The present invention relates to the technical field of supramolecular chemistry and organic synthesis, and more particularly to a method for synthesizing different sulfur-containing tridentate compounds. Background Art

[0002] In 2019, Ashish Verma et al. analyzed the crystal structure of cryptands containing bipyrazole groups and found that the length of the cryptand cage was about 2 nm, while the average size of PdNPs was 2.24 nm, indicating that about 5 or more cryptand molecules aggregated to form intermolecular cavities to stabilize the 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 alkane assembly for cell imaging. (Hui Liu, Min Lin, Yu Cui, et al. "Single-crystal structures of cucurbituril-based supramolecular host–guest complexesfor bioimaging". Chem. Commun. 2021, 57, 10190-10193.) The tridentate compound designed by Zhao Yingjie et al. is a rigid molecule. The tridentate compound is combined with CB[8] to construct a tridentate alkane assembly. The size of the intermolecular cavity formed by the aggregation of multiple assemblies is too small to be used to stabilize nanoparticles. Based on the above background technology and literature research, the present invention designs different tridentate skeletons to prepare sulfur-containing tridentate compounds, and the sulfur-containing tridentate compounds are combined with CB[8] to construct a tridentate alkane assembly. The sulfur-containing tridentate compound designed and prepared by the present invention

[0003] Tridentate compounds are flexible molecules. Sulfur-containing tridentate compounds combine with CB[8] to construct tridentate alkane assemblies. The intermolecular cavities formed by the assemblies are of suitable size and can be used to stabilize gold nanoparticles and control their size. Sulfur-containing tridentate compounds contain nitrogen and sulfur atoms. Because 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 of uniform size. Summary of the Invention

[0004] The purpose of the present invention is to propose different tridentate skeletons, synthesize sulfur-containing tridentate compounds, and then combine them with CB[8] to construct a tridentate alkane assembly, stabilize gold nanoparticles through the intermolecular cavities formed by the aggregation of the assembly, and prepare relatively uniform gold nanoparticles. The sulfur-containing tridentate compound synthesized by the present invention introduces N and S atoms. The nitrogen atom can serve as a nucleation site for gold, and the sulfur atom can form an Au-S bond with gold, making it easier to prepare gold nanoparticles of uniform size. At the same time, the preparation method of this type of sulfur-containing tridentate compound is simple. The uniformly sized gold nanoparticles prepared by the present invention have higher catalytic activity in catalytic applications.

[0005] In order to solve the technical problem of the present invention, the proposed technical solution is: the present invention provides different tridentate skeletons, whose structural formulas are:

[0006]

[0007] Where 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 method of the sulfur-containing tridentate compound and the reaction routes of different tridentate skeleton preparation methods are as follows:

[0011] Skeleton A:

[0012]

[0013] Skeleton B: .

[0015] Preferably, the reaction route of the method for preparing the sulfur-containing tridentate compound is as follows:

[0016] Compound 1a:

[0017]

[0018] Compound 1b:

[0019]

[0020] Compound 1c:

[0021] .

[0022] Application of the sulfur-containing tridentate compound in the preparation of nanoparticles.

[0023] The sulfur-containing tridentate compound is used to combine with CB[8] to construct a tridentate alkane assembly. The intermolecular cavities formed by the assembly stabilize gold nanoparticles, thereby preparing relatively uniform gold nanoparticles. The sulfur-containing tridentate compound contains nitrogen and sulfur atoms. Because the nitrogen atoms serve as nucleation sites for gold and the sulfur atoms form stable Au-S bonds with gold, it is easier to prepare gold nanoparticles of uniform size.

[0024] The present invention provides the following synthetic routes for different tridentate skeletons:

[0025] Skeleton A: Add 1,3,5-tris(4-methylphenyl)benzene, N-bromosuccinimide and benzoyl peroxide under nitrogen protection in an ice-water bath, add frozen deoxygenated carbon tetrachloride, 90 o Reflux and stir overnight at 400 °C. After the reaction is complete, cool, filter, and vacuum dry to obtain a white light solid; Reaction formula:

[0026]

[0027] Skeleton B: Add 4-cyanobenzyl bromide under nitrogen protection in an ice-water bath, add trifluoromethanesulfonic acid dropwise, and slowly warm to room temperature under natural conditions with stirring. After the reaction is complete, the precipitate formed in the ice water is neutralized with ammonia, filtered, washed, and vacuum-dried to obtain a white powder; reaction formula:

[0028]

[0029] This type of tridentate skeleton can be combined with sulfur-containing compounds to obtain different sulfur-containing tridentate compounds. This type of compound can be further combined with CB[8] to construct a tridentate alkane assembly. The intermolecular cavities formed by the aggregation of the assembly stabilize the gold nanoparticles and prepare relatively uniform gold nanoparticles.

[0030] Beneficial effects:

[0031] The present invention provides a method for preparing different tridentate skeletons. The obtained tridentate skeletons can be combined with sulfur-containing compounds to prepare different sulfur-containing tridentate compounds. The sulfur-containing tridentate compound prepared by the present invention is a flexible molecule. The sulfur-containing tridentate compound and CB[8] construct a tridentate alkane assembly. The assembly aggregates to form an intermolecular cavity of suitable size, which can be used to stabilize gold nanoparticles and control the size of gold nanoparticles. In addition, the sulfur-containing tridentate compound contains N and S atoms. Since the nitrogen atom serves as the nucleation site of gold and the sulfur atom forms a stable Au-S bond with gold, it is easier to prepare gold nanoparticles of uniform size. The gold nanoparticles of uniform size prepared by the present invention have higher catalytic activity in catalytic applications.

[0032] TEM results are as follows Figure 5 As shown in Figure 2, it can be clearly seen that the aggregates of tridentate compound 1b and CB[8] assembly are block-like structures. At the same time, the samples were characterized by scanning transmission electron microscopy (STEM). Figure 6 . Figure 6 It shows that there are gold nanoparticles with a size of about 2 nm at the edge of the block structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the H NMR spectrum of tridentate compound 1a.

[0034] Figure 2 This is the H NMR spectrum of tridentate compound 1b

[0035] Figure 3 This is the H NMR spectrum of tridentate compound 1c.

[0036] Figure 4 This is the H NMR spectrum of the tridentate compound 1b-CB[8]

[0037] Figure 5 TEM image of gold nanoparticles prepared in situ from a tridentate alkane assembly constructed with tridentate compound 1b and CB[8]

[0038] Figure 6 STEM image of gold nanoparticles prepared in situ from a tridentate alkane assembly constructed with tridentate compound 1b and CB[8] DETAILED DESCRIPTION

[0039] Example 1

[0040] The inventors designed different tridentate frameworks and combined them with sulfur-containing compounds to synthesize different sulfur-containing tridentate compounds. These sulfur-containing tridentate compounds combined with CB[8] to construct tridentate alkane assemblies. The intermolecular cavities formed by the aggregation of these assemblies can be used to stabilize gold nanoparticles and control their size.

[0041] Specific preparation methods and reaction formulas of different skeletons:

[0042] Skeleton A:

[0043] 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 double-necked reaction flask and evacuate the atmosphere with nitrogen three times. Then, add 30 mL of carbon tetrachloride (previously deoxygenated by freezing in liquid nitrogen) to the reaction flask. After the additions are complete, heat the reaction mixture to 90°C. o C, reflux and stir overnight. The reaction progress was monitored by TLC. After completion of the reaction, the mixture was cooled to room temperature and filtered. The filter cake was washed with acetone and dried under vacuum to obtain a white, lightweight solid (136 mg, 8%).

[0044] 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).

[0045] 13 C NMR (75 MHz, CDCl3) δ 142.25, 141.46, 137.72, 130.15, 128.26,125.76, 33.80.

[0046]

[0047] Skeleton B:

[0048] Weigh 4-cyanobenzyl bromide (200 mg, 1.02 mmol, 1.00 equiv.) in a Shrek flask, replace the nitrogen atmosphere, and o Trifluoromethanesulfonic acid (459.3 mg, 3.06 mmol, 3.00 equiv.) was added dropwise at 4°C, and the mixture was slowly warmed to room temperature and stirred for 12 h. After TLC analysis of the reaction, the precipitate formed in the mixture in ice water was neutralized with aqueous ammonia. The precipitate was filtered, and the filter cake was washed with acetone and dried in vacuo to yield a white powder (170 mg, 85%).

[0049] 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).

[0050] 13 C NMR (75 MHz, CDCl3) δ 171.52, 142.75, 136.52, 129.98, 129.84,33.12.

[0051] Preparation method and reaction formula of sulfur-containing compounds:

[0052]

[0053] 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 mixture of ultra-dry N,N-dimethylformamide and 1,2-dimethoxyethane (DMF / 1,2-dimethoxyethane = 5 / 4, deoxygenated by bubbling) was added. The vessel was sealed, heated to 80°C, and stirred for 48 h. After the reaction was complete by TLC, the reaction mixture was 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 over anhydrous sodium sulfate and filtered, the solvent was evaporated off under reduced pressure on a rotary evaporator, and white, shiny powder (969 mg, 82%) was obtained by silica gel column chromatography (PE:EA=2:1).

[0054] 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).

[0055] 13 C NMR (75 MHz, CDCl3) δ 150.25, 127.18, 126.56, 121.11, 15.38.

[0056] Compound R2: The two-necked flask and condenser were placed in an oven for 20 minutes, then dried using a vacuum oven for 2 minutes. The mixture was then cooled by vacuum. 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 two-necked flask. 10 mL of N,N-dimethylformamide (DMF, deoxygenated by bubbling) 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 hours. After TLC analysis of the reaction, the reaction mixture was cooled to room temperature and quickly poured onto 45 g of crushed ice, stirred until the ice melted. The pH was adjusted to 7 with aqueous hydrochloric acid, and the mixture was extracted with dichloromethane. The organic phase was collected, washed with water several times to remove DMF, dried over anhydrous sodium sulfate, and the solvent evaporated under reduced pressure. The mixture was purified by silica gel column chromatography (SiO2, PE:EA = 2:1) to yield a pale white powder (32 mg, 25%).

[0057] 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).

[0058] Preparation methods and reaction formulas of different sulfur-containing tridentate compounds:

[0059]

[0060] Compound 1a:

[0061] Skeleton A (62 mg, 0.32 mmol, 6.00 equiv.) and R1 (30 mg, 0.05 mmol, 1.00 equiv.) were weighed in a two-necked flask, and nitrogen was replaced. 3 mL of acetonitrile was added under nitrogen atmosphere. o The mixture was refluxed at 4°C for 14 h. After completion of the reaction as determined by TLC, the mixture was cooled to room temperature, filtered, and washed with dichloromethane to obtain a yellow powder (45 mg, 70%).

[0062] 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).

[0063] 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.

[0064] Compound 1b:

[0065]

[0066] Skeleton B (51.4 mg, 0.26 mmol, 5.00 equiv.) and monomer R1 (30 mg, 0.051 mmol, 1.00 equiv.) were weighed in a two-necked flask, and nitrogen was replaced. 3 mL of acetonitrile was added under nitrogen atmosphere. o The mixture was refluxed at 4°C for 14 h. After completion of the reaction as determined by TLC, the mixture was cooled to room temperature, filtered, and washed with dichloromethane to obtain a yellow powder (58 mg, 96%).

[0067] 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).

[0068] 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.

[0069] Compound 1c:

[0070]

[0071] Weigh skeleton B (30 mg, 0.16 mmol, 10.00 equiv.) and R2 (9.4 mg, 0.016 mmol, 1.00 equiv.) in a two-necked flask, replace the nitrogen atmosphere, add 3 mL of acetonitrile under nitrogen atmosphere, and 80 o The mixture was refluxed at 4°C for 14 h. After completion of the reaction as determined by TLC, the mixture was cooled to room temperature, filtered, and washed with dichloromethane to obtain a yellow powder (8 mg, 43%).

[0072] 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).

[0073] Application of the sulfur-containing tridentate compound designed by the present invention:

[0074] This type of sulfur-containing tridentate compound can combine with CB[8] to construct a tridentate alkane assembly. The intermolecular cavities formed by the aggregation of the assembly can be used to stabilize gold nanoparticles and thus control the size of the gold nanoparticles.

[0075] The experimental steps for in situ preparation of gold nanoparticles based on the cavities between compound 1b and CB[8]tri-glandane assembly and transmission electron microscopy (TEM) characterization are as follows:

[0076] The method for preparing gold nanoparticles is as follows:

[0077] The tridentate compound 1b (1.2 mg, 0.001 mmol) and CB[8] (2 mg, 0.0015 mmol) were weighed into a 1.5 mL gas phase bottle, 1 mL of deionized water was added, and 80 oC and stirred for 4 h. The reaction solution was then cooled to room temperature, and a NaAuCl₄ aqueous solution (20 μL, 0.0005 mmol) was added. The mixture was stirred vigorously at room temperature overnight. Subsequently, a NaBH₄ solution (20 μL, 0.000125 mmol) was added, and the mixture was stirred vigorously for an additional 2 minutes. Finally, the reaction solution was centrifuged at 12,000 r for 5 minutes.

[0078] 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).

[0079] Transmission electron microscopy (TEM) characterization results are as follows:

[0080] TEM results are as follows Figure 5 As shown in Figure 2, it can be clearly seen that the aggregates of tridentate compound 1b and CB[8] assembly are block-like structures. At the same time, the samples were characterized by scanning transmission electron microscopy (STEM). Figure 6 . Figure 6 It shows that there are gold nanoparticles with a size of about 2 nm at the edge of the block structure.

[0081] Gold nanoparticles have a wide range of applications. In medicine, gold nanoparticles demonstrate remarkable ability as drug carriers, precisely delivering therapeutic payloads to designated targets. In biosensors, colorimetric probes are crucial in colorimetric assays, significantly impacting detection sensitivity. Currently, metal nanoparticles, such as silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs), have been developed for 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.

[0082] The present invention designs different tridentate frameworks to prepare different sulfur-containing tridentate compounds. These compounds are combined with CB[8] to construct tridentate alkane assemblies. The intermolecular cavities formed by the aggregation of the assemblies stabilize gold nanoparticles, limiting their size. The sulfur-containing tridentate compounds contain nitrogen and sulfur atoms. Because nitrogen atoms serve as nucleation sites for gold and sulfur atoms form stable Au-S bonds with gold, uniformly sized gold nanoparticles are more easily prepared. The uniformly sized gold nanoparticles prepared by the present invention have higher catalytic activity in catalytic applications.

[0083] The present invention is not limited to the specific technical solutions described in the above embodiments, and all technical solutions formed by equivalent replacement are within the protection scope required by the present invention.

Claims

1. A sulfur-containing tridentate compound, characterized in that: The sulfur-containing tridentate compounds are two different tridentate skeletons, and their structural formulas are as follows: .

2. Wherein R represents a sulfur-containing compound, and R is R1 or R2; 。 3. The sulfur-containing tridentate compound according to claim 1, characterized in that: The compound is any one of the following structural formulas: 。 4. The method for preparing a sulfur-containing tridentate compound according to claim 1, characterized in that: The reaction routes of different tridentate framework preparation methods are as follows: Skeleton A: Skeleton B: 。 5. The method for preparing a sulfur-containing tridentate compound according to claim 1, characterized in that: The reaction route of the method for preparing the sulfur-containing tridentate compound is as follows: Compound 1a: Compound 1b: Compound 1c: 。 6. Use of the sulfur-containing tridentate compound according to claim 1 in the preparation of nanoparticles.

7. Use of the sulfur-containing tridentate compound according to claim 5 in preparing nanoparticles, characterized in that: Sulfur-containing tridentate compounds and CB[8] construct tridentate alkane assemblies. The assemblies aggregate to form intermolecular cavities that 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 of uniform size.

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