Polydentate organic ligand containing triphenylamine-bis-benzimidazolyl substituted pyridine structure as well as preparation method, product and application of polydentate organic ligand

Abstract

The invention provides a polydentate organic ligand containing a triphenylamine-bis-benzimidazolyl substituted pyridine structure as well as a preparation method, a product and application of the polydentate organic ligand, and belongs to the technical field of functional molecular materials. The multidentate organic ligand has a structure # imgabs0 # as shown in a formula I. The metal supramolecular polymer film prepared from the multidentate organic ligand and metal ions has relatively large optical contrast, relatively high color response speed and good cycle stability.

Description

Technical Field

[0001] The present invention relates to the technical field of functional molecular materials, and particularly relates to a multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure, a preparation method, a product and an application thereof. Background Technique

[0002] Metal supramolecular polymers are a novel organic-inorganic hybrid electrochromic material formed by the complexation of metal ions and multidentate ligands, combining the advantages of inorganic and organic color-changing materials. The oxidation-reduction of metal ions triggers the charge transfer between metal-ligands and the d-d* transition of metal ions, showing reversible electrochromic behavior. The metal supramolecular polymer thin film prepared based on coordination supramolecular assembly not only has excellent electrochromic performance, but also can optimize the performance of electrochromic functional materials by modifying the ligand structure or changing the types of metal ions.

[0003] Haijun Niu et al. (Chinese J Polym Sci. 2016, 34, 1091–1102) synthesized five near-infrared electrochromic polymers containing benzimidazole and triphenylamine. However, the optical contrast and cycle stability of this material are not good. Kuangguo Yan et al. (Molecules. 2023, 28, 2029) designed and synthesized two novel electrochromic aromatic polyimides with benzimidazole groups on the side chains, but the materials also have problems such as poor stability and slow response speed. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure, a preparation method, a product and an application thereof.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure, having the structure shown in Formula I:

[0007]

[0008] Among them, R1, R2, and R3 are each independently selected from the following structures:

[0009]

[0010] Another technical solution of the present invention is a preparation method of the above-mentioned multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure, comprising the following steps:

[0011] Under alkaline conditions, bis(4-bromophenyl)amine and an iodobenzene compound undergo an Ullmann reaction with cuprous iodide under the catalysis of the catalyst phenanthroline under the protection of an inert atmosphere to obtain Compound 1;

[0012] Under the protection of an inert gas, 4-hydroxypyridine-2,6-dicarboxylic acid and N-methyl-o-phenylenediamine undergo a Debus-Radziszewski reaction to obtain 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine;

[0013] Under alkaline conditions, 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine and Compound 1 undergo a nucleophilic substitution reaction to obtain a multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure;

[0014] The structural formula of the iodobenzene compound is:

[0015] The structural formula of Compound 1 is:

[0016] Wherein, R1, R2, and R3 are each independently selected from the following structures:

[0017]

[0018] In the third technical solution of the present invention, a metal supramolecular polymer is synthesized by coordination-driven by the above-mentioned multidentate organic ligand and metal ions; the metal ions are selected from Fe 2+ , Cd 2+ or Zn 2+ ; the reaction temperature for the coordination-driven synthesis of the multidentate organic ligand and metal ions is 40°C to 100°C, and the reaction time is 12h to 48h.

[0019] In the fourth technical solution of the present invention, a metal ion-ligand supramolecular polymer film is prepared by: dissolving the above-mentioned metal supramolecular polymer in an organic solvent, and then coating it on the surface of a substrate and drying.

[0020] In the fifth technical solution of the present invention, an application of the above-mentioned metal ion-ligand supramolecular polymer film in electrochromic functional materials.

[0021] The present invention discloses the following technical effects:

[0022] The present invention designs a multidentate organic ligand containing a "triphenylamine-bis(benzimidazolyl)substituted pyridine" structure. By combining triphenylamine with bis(benzimidazolyl)substituted pyridine as the multidentate organic ligand, and utilizing the propeller-shaped configuration and twisted three-dimensional spatial structure of triphenylamine, introducing it into the multidentate organic ligand structure can inhibit the solid-state stacking effect of the material, thereby enhancing the solubility of the material and providing a lower-cost and diverse way for the preparation of metal supramolecular polymer films. At the same time, bis(benzimidazolyl)substituted pyridine not only retains the advantages of bis(benzimidazole) ligands, but the presence of the N site in the pyridine group makes the electronic properties more abundant, which is beneficial to constructing coordination polymers with more diverse structures. In summary, the prepared metal supramolecular polymer film has a large optical contrast, a fast color response speed, and good cycle stability. Description of the Drawings

[0023] Figure 1 1H NMR spectrum of the target product obtained in Example 1;

[0024] Figure 2 1H NMR spectrum of the target product obtained in Example 2;

[0025] Figure 3 1H NMR spectrum of the target product obtained in Example 3;

[0026] Figure 4 Electrochromic spectrum of the metal ion-ligand supramolecular polymer film 1 obtained in Example 4;

[0027] Figure 5 Cyclic voltammogram of the metal ion-ligand supramolecular polymer film 1 obtained in Example 4;

[0028] Figure 6 Electrochromic response time spectrum of the metal ion-ligand supramolecular polymer film 1 obtained in Example 4;

[0029] Figure 7 Electrochromic stability spectrum of the metal ion-ligand supramolecular polymer film 1 obtained in Example 4. Detailed Description of the Invention

[0030] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0031] The first aspect of the present invention provides a multidentate organic ligand containing a triphenylamine-bis(benzimidazolyl)substituted pyridine structure, which is characterized by having the structure shown in Formula I:

[0032]

[0033] Among them, R1, R2, and R3 are each independently selected from the following structures:

[0034]

[0035] In some embodiments of the present invention, R1 = R2 = H, and R3 is selected from the following structures:

[0036]

[0037] The second aspect of the present invention provides a preparation method of the above-mentioned multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure, comprising the following steps:

[0038] Step 1.

[0039]

[0040] Under alkaline conditions, bis(4-bromophenyl)amine and an iodobenzene compound are subjected to an Ullmann reaction with copper(I) iodide under the catalysis of a catalyst, o-phenanthroline, under the protection of an inert atmosphere to obtain Compound 1 (a 4,4'-dibromotriphenylamine compound);

[0041] Step 2.

[0042]

[0043] Under the protection of an inert gas, 4-hydroxypyridine-2,6-dicarboxylic acid and N-methyl-o-phenylenediamine are subjected to a Debus-Radziszewski reaction to obtain 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine;

[0044] Step 3.

[0045]

[0046] Under alkaline conditions, 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine and Compound 1 are subjected to a nucleophilic substitution reaction to obtain a multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure;

[0047] In the above structural formula, R1, R2, and R3 are each independently selected from the following structures:

[0048]

[0049] In some embodiments of the present invention, the molar ratio of bis(4-bromophenyl)amine, the iodobenzene compound, copper(I) iodide, and o-phenanthroline is 1:(1 - 3):(0.04 - 0.06):(0.04 - 0.06); the temperature of the Ullmann reaction is 100 - 130 °C, and the time is 20 - 40 h.

[0050] In some embodiments of the present invention, the alkaline condition for carrying out the Ullmann reaction is provided by KOH; the molar ratio of the o-phenanthroline to KOH is (0.04 - 0.06):(5 - 12).

[0051] In some embodiments of the present invention, the solvent used for carrying out the Ullmann reaction is toluene; the dosage of the toluene is 2 - 5 ml of solvent / mmol of bis(4-bromophenyl)amine.

[0052] In the present invention, the Ullmann reaction is specifically as follows: Add the raw materials bis(4-bromophenyl)amine, iodobenzene compound, potassium hydroxide, and the catalysts o-phenanthroline and copper iodide into the reaction system, and then apply three nitrogen-vacuum cycles (first fill the reaction system with nitrogen, then evacuate until the vacuum degree > 0.095 MPa, and repeat the operation three cycles to ensure the reaction is carried out under a nitrogen atmosphere). After the solid reactants are fully infiltrated in the nitrogen atmosphere, add the solvent anhydrous toluene, and apply three nitrogen-vacuum cycles to the system again, and let the system react at 100 - 130 °C for 20 - 40 h.

[0053] In some embodiments of the present invention, after the Ullmann reaction, it further includes the steps of adding saturated brine to break the emulsion in the reaction system, then adding an extractant for extraction, then combining the organic phases and drying with anhydrous sodium sulfate, filtering by suction, evaporating the organic solvent in the filtrate under reduced pressure, eluting, and purifying by chromatography column. The extractant is dichloromethane; the volume ratio of the dichloromethane to the saturated brine is 2:2 - 1; the eluent used for eluting is a mixture of dichloromethane and petroleum ether with a volume ratio of 2 - 8:1.

[0054] In some embodiments of the present invention, the molar ratio of the 4-hydroxypyridine-2,6-dicarboxylic acid to N-methyl-o-phenylenediamine is 1:(1 - 3); the temperature of the Debus-Radziszewski reaction is 160 - 200 °C, and the time is 8 - 12 h.

[0055] In some embodiments of the present invention, the solvent used for carrying out the Debus-Radziszewski reaction is phosphoric acid; the volume concentration of the phosphoric acid is 80 - 90%; the dosage of the phosphoric acid is: 10 ml of solvent / mmol of 4-hydroxypyridine-2,6-dicarboxylic acid.

[0056] In the present invention, the Debus-Radziszewski reaction is specifically as follows: After uniformly mixing the 4-hydroxypyridine-2,6-dicarboxylic acid, N-methyl-o-phenylenediamine, and the solvent phosphoric acid, under the protection of an inert gas, stir magnetically at 160 - 200 °C for 8 - 12 h.

[0057] In some embodiments of the present invention, after the Debus-Radziszewski reaction is completed, the reaction system is cooled to room temperature, the reaction solution is poured into ice water, stirred and then filtered. The precipitate is transferred to a 10% sodium carbonate solution for washing with water and then dissolved in a hot methanol solution. Then, the pH is adjusted to 8-10, filtered, recrystallized with methanol, and dried under vacuum.

[0058] In some embodiments of the present invention, the molar ratio of the 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine to the 4,4'-dibromotriphenylamine compound is (1-3):1; the temperature of the nucleophilic substitution reaction is 40-50 °C, and the time is 18-36 h.

[0059] In some embodiments of the present invention, the basic condition for the nucleophilic substitution reaction is provided by KOH; the molar ratio of KOH to 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine is 1:(1-3).

[0060] In some embodiments of the present invention, the solvent used for the nucleophilic substitution reaction is DMSO; the dosage of DMSO is: 10 ml DMSO / mmol of the 4,4'-dibromotriphenylamine compound.

[0061] In the present invention, the nucleophilic substitution reaction is specifically as follows: under an inert atmosphere, potassium hydroxide, DMSO, and 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine are sequentially added to the reaction system. After mixing evenly, the 4,4'-dibromotriphenylamine compound is added; then, the reaction is stirred at 40-50 °C for 18-36 h.

[0062] In some embodiments of the present invention, after the nucleophilic substitution reaction is completed, it further includes the steps of cooling the reaction system to room temperature, then pouring the reaction solution into ice water, filtering and collecting the precipitate, and drying it under vacuum at room temperature.

[0063] The third aspect of the present invention provides a metal supramolecular polymer, which is synthesized by coordination driving of the above-mentioned multidentate organic ligand and metal ions; the metal ions are selected from Fe 2+ , Cd 2+ or Zn 2+ ; the reaction temperature for the coordination driving synthesis of the multidentate organic ligand and metal ions is 40 °C to 100 °C, and the reaction time is 12 h to 48 h.

[0064] In some embodiments of the present invention, the compound providing Fe 2+ is Fe(BF4)2·6H2O; the compound providing Cd 2+ is Cd(ClO4)2·6H2O; the compound providing Zn 2+ is Zn(BF4)2·6H2O).

[0065] In some embodiments of the present invention, the molar ratio of the multidentate organic ligand to the metal ion is 1:1 to 2.

[0066] In some embodiments of the present invention, after the coordination-driven synthesis, the steps further include filtering the reaction system, evaporating the filtrate under reduced pressure to dryness, washing with ethanol, and drying under vacuum to obtain a solid metal supramolecular polymer.

[0067] The fourth aspect of the present invention provides a metal ion-ligand supramolecular polymer film, and the preparation method is as follows: dissolving the above-mentioned metal supramolecular polymer in an organic solvent, then coating it on the surface of a substrate and drying. The organic solvent is methanol; the substrate is ITO conductive glass.

[0068] The technical solutions of the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are all purchased from commercial channels or have been publicly disclosed.

[0069] The cyclic voltammetry performance test method of the metal supramolecular polymer prepared by the present invention is as follows:

[0070] Using Ag / AgCl as the reference electrode, the ITO glass coated with the metal supramolecular polymer film as the working electrode, a platinum wire as the counter electrode, and an acetonitrile solution of 0.1 M tetrabutylammonium perchlorate (TBAP) as the electrolyte. Based on this three-electrode system, the cyclic voltammetry performance of the polymer is tested by an electrochemical workstation.

[0071] The test method for the electrochromic performance of the metal supramolecular polymer prepared by the present invention is as follows:

[0072] An increasing voltage is applied to the above three-electrode system by an electrochemical workstation, and during this process, the change in its absorption spectrum is monitored using a UV-visible spectrometer.

[0073] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with examples, but the content of the present invention is not limited to the following examples.

[0074] Example 1

[0075] The structure of the multidentate organic ligand is shown as follows:

[0076]

[0077] (1) Add 8.18 g (25.0 mmol) of bis(4-bromophenyl)amine, 5.10 g (25.0 mmol) of iodobenzene, 0.16 g (1.0 mmol) of copper(I) iodide, 0.18 g (1.0 mmol) of 1,10-phenanthroline and 7.01 g (0.12 mol) of potassium hydroxide into a Schlenk flask, and apply three nitrogen-vacuum cycles. Finally, add 50 ml of anhydrous toluene as the solvent, and then apply three nitrogen-vacuum cycles again. Heat to 110 °C and react for 20 h. After the reaction, extract with dichloromethane (3 × 15 ml) and saturated brine (45 ml). Combine the organic phases and dry with anhydrous sodium sulfate. Rotavaporize, and use dichloromethane / petroleum ether (V 二氯甲烷 :V 石油醚 = 2:1) as the eluent, and purify the product through a chromatographic column to obtain 5.13 g of 4,4'-dibromotriphenylamine with a yield of 51%.

[0078] (2) Add 5.05 g (25 mmol) of 4-hydroxypyridine-2,6-dicarboxylic acid and 2.70 g (25 mmol) of N-methyl-o-phenylenediamine into a round-bottom flask in a molar ratio of 1:1, add 250 ml of phosphoric acid (80%) solution, mix well, control the temperature at 160 °C, and stir magnetically for 8 h. The whole reaction process is carried out under nitrogen conditions. After the reaction, cool to room temperature, pour the reaction solution into 250 ml of ice water, stir and filter, transfer the precipitate to 250 ml of hot 10% aqueous sodium carbonate solution and stir well. Filter by suction, wash twice with water, dissolve in 250 ml of hot methanol solution, add a little hydrochloric acid to adjust the pH = 8. Filter, recrystallize with methanol, and vacuum dry to obtain 2.04 g of 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine with a yield of 46%.

[0079] (3) Add 0.31 g (5.62 mmol) of potassium hydroxide into a round-bottom flask under a nitrogen atmosphere, then add 56 ml of DMSO solution. Add 2.0 g (5.62 mmol) of 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine to this suspension and stir for 10 min, then dissolve 2.27 g (5.62 mmol) of 4,4'-dibromotriphenylamine in the reaction solution. Stir the mixture at 40 °C for 18 h. After the reaction, cool to room temperature, and then pour the reaction solution into 56 ml of ice water. Collect the precipitate by filtration and vacuum dry at room temperature to obtain 1.42 g of the target product triphenylamine-bis(benzimidazolyl)substituted pyridine compound with a yield of 41%.

[0080] Its NMR data is 11H NMR (500 MHz, CDCl3) δ 7.75–7.72 (m, 4H), 7.68–7.66 (m, 4H), 7.48 (s, 4H), 7.37–7.33 (m, 4H), 7.31–7.27 (m, 4H), 7.26–7.22 (m, 2H), 7.09–7.06 (m, 2H), 7.02–6.98 (m, 1H), 6.95 (d, J = 7.1 Hz, 4H), 6.65 (d, J = 7.0 Hz, 4H), 3.94 (s, 12H). 13 13C NMR (125 MHz, CDCl3) δ 159.91, 152.68, 149.11, 147.74, 146.80, 143.80, 136.59, 136.37, 129.28, 128.11, 127.53, 124.51, 122.71, 122.32, 121.39, 120.07, 115.88, 109.89, 31.59.

[0081] Example 2

[0082] The structure of the multidentate organic ligand is shown as follows:

[0083]

[0084] (1) Add 8.18 g (25.0 mmol) of bis(4-bromophenyl)amine, 34.81 g (50.0 mmol) of p-ethynyl iodobenzene, 0.28 g (1.5 mmol) of cuprous iodide, 0.27 g (1.5 mmol) of o-phenanthroline, and 16.82 g (0.3 mol) of potassium hydroxide to a Schlenk flask. The remaining operations and condition parameters of this step are the same as those in step (1) of Example 1. 5.96 g of 4,4'-dibromotriphenylamine compound is obtained, with a yield of 56%.

[0085] (2) Add 3.94 g (25 mmol) of 4-hydroxypyridine-2,6-dicarboxylic acid and 5.40 g (50 mmol) of N-methyl-o-phenylenediamine to a Schlenk flask in a molar ratio of 1:2. Add 250 ml of phosphoric acid (85%) solution, mix well, control the temperature at 180 °C, and stir magnetically for 10 h. The whole reaction process is carried out under nitrogen conditions. The remaining operations and condition parameters of this step are the same as those in step (2) of Example 1. 4.80 g of 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine is obtained, with a yield of 54%.

[0086] (3) Under a nitrogen atmosphere, 0.31 g (5.62 mmol) of potassium hydroxide was added to a round-bottom flask, and then 56.2 mL of DMSO solution was added. 4.0 g (11.25 mmol) of 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine was added to the suspension and stirred for 20 min. Then, 2.79 g (5.62 mmol) of 4,4'-dibromotriphenylamine was dissolved in the reaction solution. The remaining operations and condition parameters of this step were the same as those in step (3) of Example 1. 1.44 g of the target product triphenylamine-bis(benzimidazolyl)substituted pyridine compound was obtained, and the yield was 54%.

[0087] Its NMR data are as follows 1 H NMR(500MHz,CDCl3)δ7.74(d,J=8.2Hz,4H),7.67(d,J=7.5Hz,4H),7.49(d,J=13.7Hz,6H),7.35(t,J=8.0Hz,4H),7.31–7.27(m,4H),7.09(d,J=7.5Hz,2H),6.95(d,J=8.4Hz,4H),6.65(d,J=8.2Hz,4H),3.94(s,12H),2.84(s,1H). 13 CNMR(125MHz,CDCl3)δ159.91,152.68,149.11,147.74,145.53,143.80,136.59,136.37,132.82,127.53,123.11,122.71,122.32,121.39,120.07,115.88,109.89,109.25,85.09,78.79,31.59.

[0088] Example 3

[0089] The structure of the multidentate organic ligand is as follows:

[0090]

[0091] (1) 8.18 g (25.0 mmol) of bis(4-bromophenyl)amine, 17.10 g (75.0 mmol) of 4-iodobenzonitrile, 0.28 g (1.5 mmol) of copper(I) iodide, 0.27 g (1.5 mmol) of 1,10-phenanthroline and 16.82 g (0.30 mol) of potassium hydroxide were added to a Schlenk flask. The remaining operations and condition parameters of this step were the same as those in step (1) of Example 1. 5.13 g of 4,4'-dibromotriphenylamine compound was obtained, and the yield was 48%.

[0092] (2) 3.94 g (25 mmol) of 4-hydroxypyridine-2,6-dicarboxylic acid and 2.70 g (25 mmol) of N-methyl-o-phenylenediamine were added to a round-bottom flask in a molar ratio of 1:1. 250 ml of phosphoric acid (80%) solution was added, and after mixing evenly, the temperature was controlled at 160 °C and stirred for 8 h. The whole reaction process was carried out under nitrogen conditions. The remaining operations and condition parameters of this step were the same as those in step (2) of Example 1. 2.09 g of 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine was obtained, and the yield was 47%.

[0093] (3) Under a nitrogen atmosphere, 0.10 g (1.87 mmol) of potassium hydroxide was added to a round-bottom flask, and then 18 mL of DMSO solution was added. 2.0 g (5.62 mmol) of 4-hydroxy-2,6-bis(1-methyl-2-benzimidazolyl)pyridine was added to this suspension and stirred for 10 min. Then, 0.8 g (1.87 mmol) of 4,4'-dibromotriphenylamine compound was dissolved in the reaction solution. The remaining operations and condition parameters of this step were the same as those in step (3) of Example 1. 0.45 g of the target product triphenylamine-bis(benzimidazolyl)substituted pyridine compound was obtained, and the yield was 51%.

[0094] Its NMR data are as follows 1 H NMR (500 MHz, CDCl3) δ 7.74 (d, J = 8.2 Hz, 4H), 7.67 (d, J = 7.5 Hz, 4H), 7.49 (d, J = 13.7 Hz, 6H), 7.35 (t, J = 8.0 Hz, 4H), 7.31–7.27 (m, 4H), 7.09 (d, J = 7.5 Hz, 2H), 6.95 (d, J = 8.4 Hz, 4H), 6.65 (d, J = 8.2 Hz, 4H), 3.94 (s, 12H), 2.84 (s, 1H). 13 C NMR (125 MHz, CDCl3) δ 159.91, 152.68, 149.11, 147.74, 147.62, 143.80, 136.59, 136.37, 131.24, 127.53, 122.71, 122.32, 121.39, 120.07, 118.13, 115.88, 109.89, 106.72, 31.59.

[0095] Using steps similar to those in the above examples, only replacing the corresponding raw materials, the following compounds were prepared. The structures and 1H NMR data of the compounds are shown in Table 1.

[0096] Table 1 1H NMR data of the compounds

[0097]

[0098]

[0099]

[0100]

[0101] Example 4

[0102] The target ligand and Fe(BF4)2·6H2O were polymerized to obtain a metal ion-ligand supramolecular polymer film 1:

[0103] Weighed 89.6 mg (0.1 mmol) of the target ligand prepared in Example 1 and 33.8 mg (0.1 mmol) of Fe(BF4)2·6H2O and dissolved them in 100 ml of glacial acetic acid. The mixture was refluxed at 40 °C for 12 h to completely complex the ligand with the metal ions. After the reaction, the mixture was filtered and the filtrate was evaporated under reduced pressure. The product was washed with ethanol several times and then dried in vacuo to obtain 62 mg of a solid metal supramolecular polymer.

[0104] Dissolved 50 mg of the above solid in 100 ml of methanol, filtered out the insoluble matter, took 40 ml of the solution and added it to the spray pot of an airbrush, then sprayed it onto the surface of ITO conductive glass, and placed it in an oven to dry at 30 °C for 12 h. After the methanol evaporated on the ITO glass surface, a uniform metal ion-ligand supramolecular polymer film was obtained, labeled as film 1.

[0105] Example 5

[0106] The target ligand and Zn(BF4)2·6H2O were polymerized to obtain a metal ion-ligand supramolecular polymer film 2:

[0107] Weighed 92.0 mg (0.1 mmol) of the target ligand prepared in Example 2 and 50.7 mg (0.125 mmol) of Fe(BF4)2·6H2O and dissolved them in 100 ml of glacial acetic acid. The mixture was refluxed at 60 °C for 18 h to completely complex the ligand with the metal ions. After the reaction, the mixture was filtered and the filtrate was evaporated under reduced pressure. The product was washed with ethanol several times and then dried in vacuo to obtain 59 mg of a solid metal supramolecular polymer.

[0108] Dissolved 25 mg of the above solid in 50 ml of methanol, filtered out the insoluble matter, took 40 ml of the solution and added it to the spray pot of an airbrush, then sprayed it onto the surface of ITO conductive glass, and placed it in an oven to dry at 38 °C for 36 h. After the methanol evaporated on the ITO glass surface, a uniform metal ion-ligand supramolecular polymer film was obtained, labeled as film 2.

[0109] Example 6

[0110] The target ligand and Fe(BF4)2·6H2O are polymerized to obtain a metal ion-ligand supramolecular polymer film 3:

[0111] Weigh 94.1 mg (0.1 mmol) of the target ligand prepared in No. 8 and 43.4 mg (0.15 mmol) of Zn(BF4)2·6H2O, dissolve them in 100 ml of glacial acetic acid, reflux and react at 70 °C for 24 h to completely complex the ligand with the metal ions. After the reaction, filter and evaporate the filtrate under reduced pressure. Wash the product with ethanol multiple times and then dry it in vacuo to obtain 66 mg of a solid metal supramolecular polymer.

[0112] Take 30 mg of the above solid and dissolve it in 60 ml of methanol. Filter out the insoluble matter. Take 45 ml of the solution and add it to the spray pot of an airbrush, then spray it onto the surface of ITO conductive glass, put it into an oven, and dry it at 40 °C for 24 h. After the methanol volatilizes on the surface of the ITO glass, a uniform metal ion-ligand supramolecular polymer film is obtained, marked as film 3.

[0113] Example 7

[0114] The target ligand and Cd(ClO4)2·6H2O are polymerized to obtain a metal ion-ligand supramolecular polymer film 4:

[0115] Weigh 89.6 mg (0.1 mmol) of the target ligand prepared in No. 5 and 73.3 mg (0.175 mmol) of Cd(ClO4)2·6H2O, dissolve them in 100 ml of glacial acetic acid, reflux and react at 80 °C for 36 h to completely complex the ligand with the metal ions. After the reaction, filter and evaporate the filtrate under reduced pressure. Wash the product with ethanol multiple times and then dry it in vacuo to obtain 53 mg of a solid metal supramolecular polymer.

[0116] Take 25 mg of the above solid and dissolve it in 50 ml of methanol. Filter out the insoluble matter. Take 40 ml of the solution and add it to the spray pot of an airbrush, then spray it onto the surface of ITO conductive glass, put it into an oven, and dry it at 45 °C for 36 h. After the methanol volatilizes on the surface of the ITO glass, a uniform metal ion-ligand supramolecular polymer film is obtained, marked as film 4.

[0117] Example 8

[0118] The target ligand and Cd(ClO4)2·6H2O are polymerized to obtain a metal ion-ligand supramolecular polymer film 5:

[0119] Weigh 89.6 mg (0.1 mmol) of the target ligand prepared in No. 10 and 41.9 mg (0.2 mmol) of Cd(ClO4)2·6H2O, dissolve them in 100 ml of glacial acetic acid, reflux and react at 100 °C for 48 h to completely complex the ligand with metal ions. After the reaction, filter and evaporate the filtrate under reduced pressure. Wash the product with ethanol multiple times and then dry it under vacuum to obtain 57 mg of solid metal supramolecular polymer.

[0120] Dissolve 25 mg of the above solid in 50 ml of methanol, filter out the insoluble substances, take 40 ml of the solution and add it to the spray pot of an airbrush, then spray it onto the surface of ITO conductive glass, put it into an oven and dry it at 50 °C for 36 h. After the methanol volatilizes on the surface of the ITO glass, a uniform metal ion-ligand supramolecular polymer film is obtained, marked as Film 5.

[0121] Characterization and performance testing

[0122] 1) Figure 1 1H NMR spectrum of the target product 4-((2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yl)oxy)-N-(4-((2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yl)oxy)phenyl)-N-phenylaniline described in Example 1; the peak positions and integral peak areas are all consistent with the structure, indicating the successful preparation of the target organic ligand.

[0123] 2) Figure 2 1H NMR spectrum of the target product 4-((2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yl)oxy)-N-(4-((2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yl)oxy)phenyl)-N-(4-ethynylphenyl)aniline described in Example 2; the peak positions and integral peak areas are all consistent with the structure, indicating the successful preparation of the target organic ligand.

[0124] 3) Figure 3 1H NMR spectrum of the target product 4-[bis(4-((2,6-di(1-methyl-1H-benzo[d]imidazol-2-yl)pyridin-4-yl)oxy)phenyl)amino]benzonitrile described in Example 3; the peak positions and integral peak areas are all consistent with the structure, indicating the successful preparation of the target organic ligand.

[0125] 4) Since the absorption of the UV-Vis absorption spectra of several thin films is roughly the same, the electrochromic spectra of the metal supramolecular polymer labeled as Film 1 in Example 4 are used as a representative to verify the preparation of the thin films. The test method is as follows: Using an electrochemical workstation, apply a voltage of 1.3 V to the working electrode in the Amperometric i-t Curve mode, and simultaneously monitor the change in absorbance at different wavelengths with a UV-Vis-NIR spectrophotometer. As Figure 4 shown, after adding metal ions, new absorption peaks appear in the UV-Vis absorption spectrum of the thin film, which confirms the successful preparation of the metal supramolecular polymer.

[0126] 5) Perform cyclic voltammetry performance testing on the metal supramolecular polymer thin film labeled as 1 prepared in Example 4. The method is as follows: Use the ITO containing the metal supramolecular polymer thin film 1 as the working electrode, a platinum wire as the counter electrode, and Ag / AgCl as the reference electrode. Use an acetonitrile solution of 0.1 M tetrabutylammonium perchlorate (TBAP) as the electrolyte; Based on this three-electrode system, test the cyclic voltammetry performance through an electrochemical workstation in the range of a scan rate of 40 - 100. The obtained results are shown in Figure 5 , Figure 5 which is the cyclic voltammogram of the metal supramolecular polymer labeled as Film 1 in Example 4; It can be seen from Figure 5 that the metal supramolecular polymer thin film labeled as 1 has a pair of reversible redox potentials.

[0127] 6) Figure 6 which is the electrochromic response time spectrum of the metal supramolecular polymer labeled as Film 1 in Example 4; The test method is as follows: Using an electrochemical workstation, apply a square wave voltage of 0.00 - 1.30 V to the working electrode in the Chronoamperometry mode, and simultaneously monitor the change in the absorption spectrum at 576 nm with a UV-Vis-NIR spectrophotometer. It can be seen from Figure 6 that the metal supramolecular polymer thin film labeled as 1 has a fast response speed.

[0128] 7) Figure 7 which is the electrochromic stability spectrum of the metal supramolecular polymer labeled as Film 1 in Example 4; It can be seen from Figure 7 that after 100 cycles, the curve does not show obvious attenuation, proving that the structure of the metal supramolecular polymer labeled as 1 has stable electrochromic conversion performance.

[0129] 8) Perform solubility testing on the metal supramolecular polymers prepared in Examples 4 - 8. The solution concentrations of different metal supramolecular polymers formed in different solvents are all 2 mg / mL; The obtained results are shown in Table 2.

[0130] 9) The optical contrast, response speed, and cyclic stability (attenuation of the film optical contrast after 1000 s) of the metal supramolecular polymers prepared in Examples 4-8 were tested, and the results are shown in Table 3.

[0131] Table 2 Solubility of the metal supramolecular polymers prepared in Examples 4-8 in 6 common solvents

[0132]

[0133] Note: ++: Soluble at room temperature; +: Soluble upon heating; +-: Partially soluble; -: Insoluble upon heating.

[0134] Table 3 Optical contrast, response speed, and cyclic stability (attenuation of the film optical contrast after 1000 s) of the metal supramolecular polymers prepared in Examples 4-8

[0135]

[0136]

[0137] The present invention also prepared metal supramolecular polymer films by using compounds with structures other than those in Examples 1, 2, No. 8, No. 5, and No. 10 and metal ions, and verified the optical contrast, response speed, cyclic stability, and solubility of the obtained films. The results show that the metal supramolecular polymer films prepared from the multidentate organic ligands of the structure of the present invention and metal ions have a large optical contrast, a fast color response speed, good cyclic stability, and good solubility in common organic solvents.

[0138] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure, characterized in that, It has the structure shown in Formula I: Wherein, R1, R2, and R3 are each independently selected from the following structures:

2. A preparation method of the multi-dentate organic ligand containing a triphenylamine-bis(benzimidazolyl) substituted pyridine structure as described in claim 1, characterized in that, It includes the following steps: Under alkaline conditions, bis(4-bromophenyl)amine and an iodobenzene compound react with copper(I) iodide under the catalysis of the catalyst 1,10-phenanthroline under the protection of an inert atmosphere to carry out the Ullmann reaction to obtain Compound 1; Under the protection of an inert gas, 4-hydroxypyridine-2,6-dicarboxylic acid and N-methyl-o-phenylenediamine carry out the Debus-Radziszewski reaction to obtain 4-hydroxy-2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridine; Under alkaline conditions, 4-hydroxy-2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridine and Compound 1 carry out a nucleophilic substitution reaction to obtain a multidentate organic ligand containing a triphenylamine-bisbenzimidazolyl-substituted pyridine structure; The structural formula of the iodobenzene compound is as follows: The structural formula of the said Compound 1 is as follows: Wherein, R1, R2, and R3 are each independently selected from the following structures:

3. The preparation method according to claim 2, characterized in that, The molar ratio of the bis(4-bromophenyl)amine, iodobenzene compound, copper(I) iodide, and 1,10-phenanthroline is 1:(1-3):(0.04-0.06):(0.04-0.06); the temperature of the Ullmann reaction is 100-130 °C, and the time is 20-40 h.

4. The preparation method according to claim 2, wherein The alkaline condition for carrying out the Ullmann reaction is provided by KOH; the molar ratio of the 1,10-phenanthroline and KOH is (0.04-0.06):(5-12).

5. The preparation method according to claim 2, characterized in that, The molar ratio of the 4-hydroxypyridine-2,6-dicarboxylic acid and N-methyl-o-phenylenediamine is 1:(1-3); the temperature of the Debus-Radziszewski reaction is 160-200 °C, and the time is 8-12 h.

6. The preparation method according to claim 2, characterized in that, The molar ratio of the 4-hydroxy-2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridine and the 4,4'-dibromotriphenylamine compound is (1-3):1; the temperature of the nucleophilic substitution reaction is 40-50 °C, and the time is 18-36 h.

7. The preparation method according to claim 2, characterized in that, The alkaline condition for carrying out the nucleophilic substitution reaction is provided by KOH; the molar ratio of the KOH and 4-hydroxy-2,6-bis(1-methyl-1H-benzo[d]imidazol-2-yl)pyridine is 1:(1-3).

8. A metal supramolecular polymer, characterized in that, Synthesis driven by coordination of the multidentate organic ligand described in claim 1 and a metal ion; the metal ion is selected from Fe 2+ , Cd 2+ or Zn 2+ ; the reaction temperature for the synthesis driven by the coordination of the multidentate organic ligand and the metal ion is 40°C to 100°C, and the reaction time is 12 h to 48 h.

9. A metal ion-ligand supramolecular polymer thin film, characterized in that, The preparation method is: dissolving the metal supramolecular polymer described in Claim 8 in an organic solvent, then coating it on the surface of a substrate and drying.

10. Use of the metal ion-ligand supramolecular polymer film described in Claim 9 in electrochromic functional materials.

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