A method for synthesizing an n-arylated viologen molecule containing an aldehyde group

Abstract

The application discloses a synthesis method of an aldehyde group-containing N-arylated viologen molecule, and the method adopts a Nesmeyanov reaction to prepare the aldehyde group-containing N-arylated viologen molecule by reacting a pyridine compound and an asymmetric iodonium molecule containing an aldehyde group. The synthesis method provided by the application is simple in process, easy to purify, high in yield and strong in universality. The prepared molecule has excellent electrochemical performance and electrochromic performance. The introduction of the aldehyde group further expands the space of modification, provides unlimited possibilities for constructing various functional materials containing viologen, and is expected to be applied to multiple fields such as electrochromic, optical chromic, energy storage, adsorption, supramolecular chemistry, catalysis and sensing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic functional material synthesis, and particularly relates to a synthesis method of an N-arylated viologen molecule containing an aldehyde group. BACKGROUND

[0002] Viologen compounds are a kind of classic n-type semiconductor materials, have excellent electron-accepting ability, and are widely used in electrochromic, supramolecular assembly, energy storage and other fields. The common modification method mainly introduces a conjugated group between two pyridine units to achieve the purpose of regulating the photoelectric performance. However, this method is limited to the structure design of small molecules, and cannot realize the construction of more complex functional systems such as polymers and covalent organic frameworks (COF). The aldehyde group is a common chemical element that can react with amino, hydroxyl and other units. Many literatures use aldehyde groups and amino groups to create COF materials with diverse structures, achieving applications in photocatalysis, gas adsorption, energy storage and electrochromism. Therefore, introducing an aldehyde group into the rigid viologen structure provides extensive space for the construction of new functional materials.

[0003] At present, there is only one structure of N-arylated viologen molecules containing an aldehyde group reported in the literature. The synthesis method mainly uses the classic Zincke reaction. The biggest disadvantage of this method is: 1) the synthesis process involves protection / deprotection of the aldehyde group, the steps are numerous, and the overall yield is low (Angew. Chem. Int. Ed. 2015, 54, 4028-4031); 2) the scope is narrow, especially for strong electron-withdrawing systems (J. Am. Chem. Soc. 2015, 137, 11710-11717). Therefore, it is necessary to develop a simple and widely applicable synthesis method of N-arylated viologen molecules containing an aldehyde group. SUMMARY

[0004] In order to solve the limitations of the Zincke reaction route, the application provides a simple and widely applicable synthesis method of N-arylated viologen molecules containing an aldehyde group through the Nesmeyanov reaction.

[0005] In order to achieve the above purposes, the technical scheme adopted by the application is as follows: under a nitrogen atmosphere, a compound of formula B, a compound of formula C or C', and copper acetate monohydrate are added to a reaction solvent, the reaction mixture is reacted at 80-150 DEG C for 12-72 hours, after the reaction is completed, it is cooled to room temperature, precipitated by adding diethyl ether, the precipitate is collected by filtration, washed with diethyl ether, and vacuum dried to obtain the corresponding target compound. The reaction equation is as follows:

[0006]

[0007] In the formula, L is a linking unit, which is selected from any one of the following structures:

[0008]

[0009] X - represents an anion, which can be any one of BF4 - , PF6 - , ClO4 - , Cl - , Br - , I - , etc.; m represents the number of anions, which depends on the number of positive charges in the molecular skeleton, and can be any integer from 2 to 4; R1 and R2 each independently represent hydrogen, C2-C9 alkyl, halogen, C2-C9 alkoxy, nitro, ester, cyano, or any one of aromatic groups with a benzene ring number of 1-5.

[0010] In the above synthesis method, the molar ratio of the compound of formula B, the compound of formula C or C', and copper acetate monohydrate is preferably 1:2-6:0.1-1.

[0011] In the above synthesis method, the reaction is preferably carried out at 100-120°C for 20-30 hours.

[0012] In the above synthesis method, the reaction solvent is preferably any one of N,N-dimethylformamide (DMF), toluene, 1,4-dioxane, dimethyl sulfoxide, and tetrahydrofuran.

[0013] The beneficial effects of the present application are as follows:

[0014] The synthesis method of the present application is simple, easy to purify, high in yield, and strong in universality, and the obtained aldehyde group-containing N-arylated viologen molecule has excellent electron-accepting ability and electrochromic performance. The introduction of the aldehyde group further expands the space for modification, providing unlimited possibilities for the construction of various functional materials containing viologen, and is expected to be applied in the fields of electro / optical chromism, energy storage, adsorption, supramolecular chemistry, catalysis, and sensing. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is the nuclear magnetic hydrogen spectrum of the compound B-1 of formula.

[0016] Figure 2 is the nuclear magnetic hydrogen spectrum of the target compound V-CHO prepared in Example 1.

[0017] Figure 3 is the nuclear magnetic hydrogen spectrum of the target compound BtV-CHO prepared in Example 2.

[0018] Figure 4 is the nuclear magnetic hydrogen spectrum of the target compound AnV-CHO prepared in Example 3.

[0019] Figure 5 is the nuclear magnetic hydrogen spectrum of the target compound TTzV-CHO prepared in Example 4.

[0020] Figure 6 is the nuclear magnetic hydrogen spectrum of the target compound TPTV-CHO prepared in Example 5.

[0021] Figure 7 is the cyclic voltammetry curve of the compound V-CHO prepared in Example 1.

[0022] Figure 8 is the cyclic voltammetry curve of the compound BtV-CHO prepared in Example 2.

[0023] Figure 9 is the cyclic voltammetry curve of the compound AnV-CHO prepared in Example 3.

[0024] Figure 10 is the cyclic voltammetry curve of the compound TTzV-CHO prepared in Example 4.

[0025] Figure 11 is the ultraviolet spectrum change of the compound V-CHO prepared in Example 1 under the condition of power-on. DETAILED DESCRIPTION

[0026] The application will be further described in detail below in conjunction with the drawings and examples, but the protection scope of the application is not limited to these examples. Any modification, equivalent replacement and improvement made in the spirit and principle of the application shall be within the protection scope of the application.

[0027] The compound B-1 of formula used in the following examples was synthesized by the method in the reference "Chem. Commun., 2017, 53, 7022-7025", and the specific synthesis route and synthesis method are as follows:

[0028]

[0029] A solution of 25 g (102 mmol) of 2,4,6-trimethylbenzene iodide and 25 g (122 mmol) of meta-chloroperoxybenzoic acid (m-CPBA) in 100 mL of acetic acid was stirred at room temperature for 24 h. After the reaction was completed, the solid was filtered under suction, washed with petroleum ether, and dried to obtain a white solid, which was the compound of formula A, with a yield of 90%. At 0°C, 2.96 mL (23.97 mmol) of boron trifluoride etherate was added to a solution of 50 mL of 1.2 g (7.99 mmol) of p-formylphenylboronic acid in dichloromethane, and after stirring for 15 min, 3.2 g (8.79 mmol) of the compound of formula A was added, and the reaction was carried out at room temperature for 10 h. After the reaction was completed, 40 mL of a solution of 2.1 g of sodium tetrafluoroborate in water was added, and after stirring at room temperature for 3 h, the organic phase was extracted with dichloromethane, and the combined organic phases were dried over anhydrous magnesium sulfate, filtered, and 20 mL of ether was added, stirred at room temperature for 30 min, and filtered under suction to obtain the compound of formula B-1, with a yield of 90%. The structural characterization data of the compound of formula B-1 are shown in Table 1 (see Figure 1 ) : 1 H NMR (600 MHz, d6-DMSO): δ (ppm) = 10.00 (s, 1H; CHO), 8.16 (d, J = 8.4 Hz, 2H; ArH), 7.96 (d, J = 8.4 Hz, 2H; ArH), 7.24 (s, 2H; ArH), 2.60 (s, 6H; CH3), 2.30 (s, 3H; CH3).

[0030] The compound of formula C-1 in the following examples was synthesized according to the method in the reference "Synthesis., 2014, 46, 2976-2982", and the specific synthesis route and synthesis method are as follows:

[0031]

[0032] A 500 mL dry two-necked flask was sequentially added 2.0 g (6.17 mmol) of 5,5'-dibromo-2,2'-bithiophene, 1.67 g (13.6 mmol) of 4-pyridineboronic acid, 5.1 g (37.0 mmol) of potassium carbonate, and 357 mg (0.31 mmol) of tetrakis(triphenylphosphine)palladium, and then the whole system was vacuumed and purged with N2 for three times, and then 100 mL of toluene, 50 mL of methanol, and 20 mL of water were added, and the reaction was stirred at 85°C for 48 h. After the reaction was completed, it was naturally cooled, the reaction solvent was rotary evaporated, and then purified by silica gel column chromatography, with a mixture of dichloromethane and methanol (4:1 by volume) as the eluent, to obtain 1.3 g of a white solid, which was the compound of formula C-1, with a yield of 66%.

[0033] The compound of formula C-2 in the following example was synthesized according to the method in the reference "Dalton Trans., 2021, 50, 7944-7948". The specific synthesis route and synthesis method are as follows:

[0034]

[0035] Into a 500 mL dry two-necked flask, 1.01 g (3 mmol) of 9,10-dibromoanthracene, 0.92 g (7.5 mmol) of 4-pyridineboronic acid, 4.15 g (30.0 mmol) of potassium carbonate and 350 mg (0.30 mmol) of tetrakis(triphenylphosphine)palladium were sequentially added, after which the whole system was vacuumed and purged with N2 for three times, then 150 mL of N,N-dimethylformamide and 15 mL of water were added, and it was stirred at 100°C under a nitrogen atmosphere and reacted for 24 h. After the reaction was cooled, the reaction solvent was spin-dried in a rotary evaporator, and then purified by silica gel column chromatography to obtain 816 mg of yellow solid, i.e. the compound of formula C-2, with a yield of 82%.

[0036] The compound of formula C-3 in the following example was synthesized according to the method in the reference "Angew. Chem. Int. Ed. 2018, 57, 231-235". The specific synthesis route and synthesis method are as follows:

[0037]

[0038] 20 mL (216 mmol) of 4-pyridinecarboxaldehyde and 10 g (83.4 mmol) of dithiooxamide were stirred in DMF solvent under reflux for 24 h. After the reaction was cooled to room temperature, it was filtered under vacuum, and the obtained solid product was washed with water to obtain 19.2 g of the compound of formula C-3, with a yield of 77%.

[0039] The compound of formula C-4 in the following example was synthesized according to the method in the reference "Nat Commun., 2015, 6, 8348". The specific synthesis route and synthesis method are as follows:

[0040]

[0041] 10 g (96 mmol) of 4-cyanopyridine, 1 g (3.8 mmol) of 18-crown-6 ether, and 225 mg (4.0 mmol) of potassium hydroxide were reacted in decaline at 200°C for 3 h. After the reaction was completed, the obtained solid was acidified and dissolved with hydrochloric acid, then a small amount of insoluble impurities was filtered, and the filtrate was acidified and filtered under vacuum to obtain 7.4 g of the solid product, i.e. the compound of formula C-4, with a yield of 74%.

[0042] Example 1

[0043]

[0044] Into a 25 mL dry two-necked flask, 156 mg (1 mmol) of 4,4'-dipyridyl (compound of formula C'-1), 1.3 g (3 mmol) of compound of formula B-1 and 18 mg (0.1 mmol) of copper acetate monohydrate were sequentially added, after which the whole system was vacuumed and purged with N2 three times, 2 mL of analytical pure DMF was then added, the temperature was raised to 100 °C, stirring was performed and the reaction was allowed to proceed for 24 h. After the reaction was completed, the system was allowed to cool to room temperature, ether was added to precipitate, the precipitate was collected by filtration, washed with ether and dried under vacuum to obtain the target compound V-CHO in a yield of 97%, the structural characterization data of which are shown in Table 1 (see Figure 2 ) : 1 HNMR (400 MHz, d6-DMSO): δ (ppm) = 10.22 (s, 2H; CHO), 9.77 (d, J = 6.6 Hz, 4H; C5H4N), 9.12 (d, J = 6.6 Hz, 4H; C5H4N), 8.32 (d, J = 8.4 Hz, 4H; C6H4), 8.20 (d, J = 8.4 Hz, 4H; C6H4).

[0045] Example 2

[0046]

[0047] In this example, an equimolar amount of compound of formula C-1 was used to replace 4,4'-dipyridyl (compound of formula C'-1) in Example 1, and the other steps were the same as those in Example 1 to obtain BtV-CHO in a yield of 94%, the structural characterization data of which are shown in Table 1 (see Figure 3 ) : 1 HNMR (400 MHz, d6-DMSO): δ (ppm) = 10.19 (s, 2H; CHO), 9.33 (d, J = 7.2 Hz, 4H; C5H4N), 8.57 (m, 6H; C5H4N and C4H2S), 8.28 (d, J = 8.8 Hz, 4H; C6H4), 8.13 (d, J = 8.8 Hz, 4H; C6H4), 8.00 (d, J = 4.0 Hz, 2H; C4H2S).

[0048] Example 3

[0049]

[0050] In this example, an equimolar amount of compound of formula C-2 was used to replace 4,4'-dipyridyl (compound of formula C'-1) in Example 1, and the other steps were the same as those in Example 1 to obtain AnV-CHO in a yield of 95%, the structural characterization data of which are shown in Table 1 (see Figure 4 ) : 1HNMR (400 MHz, d6-DMSO): δ (ppm) = 10.25 (s, 2H; CHO), 9.68 (d, J = 6.4 Hz, 4H; C5H4N), 8.55 (d, J = 6.4 Hz, 4H; C5H4N), 8.39 (d, J = 8.4 Hz, 4H; C6H4), 8.29 (d, J = 8.4 Hz, 4H; C6H4), 7.84 (m, 4H; anthracene ArH), 7.70 (m, 4H; anthracene ArH).

[0051] Example 4

[0052]

[0053] In this example, 6.7 mmol of compound C-4 is used to replace 10 mmol of 4,4'-bipyridine (compound C'-l) in Example 1, and other steps are the same as in Example 1 to obtain TPTV-CHO with a yield of 99%, and the structural characterization data are shown in Table 1. Figure 5 1 H NMR (400 MHz, d6-DMSO): δ (ppm) = 10.25 (s, 2H; CHO), 9.68 (d, J = 6.4 Hz, 4H; C5H4N), 8.55 (d, J = 6.4 Hz, 4H; C5H4N), 8.39 (d, J = 8.4 Hz, 4H; C6H4), 8.29 (d, J = 8.4 Hz, 4H; C6H4), 7.84 (m, 4H; anthracene ArH), 7.70 (m, 4H; anthracene ArH).

[0054] Example 5

[0055]

[0056] In this example, 6.7 mmol of compound C-4 is used to replace 10 mmol of 4,4'-bipyridine (compound C'-l) in Example 1, and other steps are the same as in Example 1 to obtain TPTV-CHO with a yield of 99%, and the structural characterization data are shown in Table 1. Figure 6 1 H NMR (400 MHz, d6-DMSO): δ (ppm) = 10.25 (s, 2H; CHO), 9.68 (d, J = 6.4 Hz, 4H; C5H4N), 8.55 (d, J = 6.4 Hz, 4H; C5H4N), 8.39 (d, J = 8.4 Hz, 4H; C6H4), 8.29 (d, J = 8.4 Hz, 4H; C6H4), 7.84 (m, 4H; anthracene ArH), 7.70 (m, 4H; anthracene ArH).

[0057] The target products prepared in Examples 1-5 above were characterized for electrochemical performance, and the results are shown in Table 2. Figures 7 to 10 The cyclic voltammograms show that the target products prepared have excellent electron-accepting ability, and the performance is closely related to the molecular skeleton. Figure 7 ​​As shown, V-CHO has two pairs of clear reversible redox peaks (-0.63 / -0.55 V, -0.80 / -0.72 V). As shown in Figure 2B, the UV spectra of V-CHO under applied electric conditions. When the applied voltage is in the range of 0 to -0.2 V (vs. Ag / AgCl), the molecule changes from the divalent ion state to the cation radical state, accompanied by the appearance of strong absorption peaks at 451 nm, 675 nm and 746 nm. When the applied voltage is increased to -0.4 V (vs. Ag / AgCl), the molecule changes from the cation radical state to the neutral state, and the absorption peaks at 675 nm and 746 nm gradually weaken, and new absorption peaks appear at 500-600 nm. Figures 8 to 10 As shown, linear BtV-CHO, AnV-CHO and TTzV-CHO with conjugated units connected in the middle all have one-step, two-electron reduction processes, with redox potentials at -0.99 / -0.85 V, -0.95 / -0.74 V and -0.68 / -0.52 V, respectively.

[0058] In addition, the target products prepared have excellent electrochromic properties. Figure 11 is the UV spectrum of the compound V-CHO prepared in Example 1 under applied electric conditions. When the applied voltage is in the range of 0 to -0.2 V (vs. Ag / AgCl), the molecule changes from the divalent ion state to the cation radical state, accompanied by the appearance of strong absorption peaks at 451 nm, 675 nm and 746 nm. When the applied voltage is increased to -0.4 V (vs. Ag / AgCl), the molecule changes from the cation radical state to the neutral state, and the absorption peaks at 675 nm and 746 nm gradually weaken, and new absorption peaks appear at 500-600 nm.

Claims

1. A method for the synthesis of an aldehyde group containing N- arylated viologen molecule, characterized by: Under nitrogen atmosphere, the compound of formula B, the compound of formula C or C', copper acetate monohydrate are added into a reaction solvent, the reaction mixture is reacted at 80-150 ℃ for 12-72 hours, after the reaction is completed, it is cooled to room temperature, precipitated after adding ether, the precipitate is collected by filtration, washed with ether, and dried under vacuum to obtain the corresponding target compound; the reaction equation is shown as follows: In the formula, L is a connecting unit, selected from any one of the following structures: X - represents an anion selected from any one of BF4 - , PF6 - , CIO4 - , CI - , Br - , I - ; m represents the number of anions and is an integer selected from 2 to 4 depending on the number of positive charges in the molecular skeleton; R1and R2each independently represents any one of hydrogen, C2to C9alkyl, halogen, C2to C9alkoxy, nitro, ester, cyano, and an aromatic group having 1 to 5 benzene rings.

2. The method of synthesis of aldehyde group containing N- arylated viologen molecules according to claim 1, characterized in that: The molar ratio of the compound of formula B, the compound of formula C or C', copper acetate monohydrate is 2-6:1:0.1-1.

3. The method for synthesizing N-aryl viologen molecules containing aldehyde groups according to claim 1, characterized in that: The reaction is carried out at 100-120 ℃ for 20-30 hours.

4. The method for synthesizing N-aryl viologen molecules containing aldehyde groups according to claim 1, characterized in that: The reaction solvent is any one of N,N-dimethylformamide, toluene, 1,4-dioxane, dimethyl sulfoxide, tetrahydrofuran.

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