Reversible coordination cross-linking agent and wavelength / temperature orthogonal control method thereof

Abstract

The invention discloses a reversible coordination cross-linking agent and a wavelength / temperature orthogonal control method thereof. The structure of the reversible coordination cross-linking agent is shown as follows: # imgabs0 #. Orthogonal coordination is formed by the reversible coordination cross-linking agent and acetonitrile in an aqueous solution at different temperatures, and orthogonal decoordination is formed by light with different wavelengths. The invention provides a novel compound containing two ruthenium centers in a single molecule, orthogonal control of various paths can be realized, a novel multi-stimulus orthogonal strategy is provided, and the compound is suitable for orthogonally and reversibly controlling crosslinking and decrosslinking of polymers by light and heat, especially in the fields of photoresponse hydrogel, 4D printing materials and the like, and has a wide application prospect. And programmable control of a dynamic network can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of light-responsive polymer materials, and in particular relates to a reversible coordination cross-linking agent and a wavelength / temperature orthogonal control method thereof. Background Art

[0002] Multi-stimulus orthogonal control of reversible coordination crosslinkers is the core of realizing multi-dimensional regulation of smart materials, but its development is limited by insufficient stimulus orthogonality and limitations of molecular design. Traditional solutions mostly rely on multi-molecular synergistic mechanisms (such as mixing two different photosensitive molecules). Although they can achieve step-by-step response, they face inherent problems such as uneven component diffusion, frequent interface side reactions, and poor cyclic stability. Although single-molecule systems (such as mononuclear ruthenium complexes) avoid multi-component interference, their single function means that they can only respond to a single stimulus (such as light or heat), which cannot meet the needs of complex scenarios. In addition, existing photoresponsive systems generally have spectral overlap problems (such as azobenzene and nitrobenzyl ester both respond to ultraviolet light), making it difficult to achieve site-specific dissociation through wavelength selection, which seriously limits the spatiotemporal programming capabilities.

[0003] Based on this, the development of an orthogonally controlled single-molecule reversible cross-linker has important application value and research significance. The cross-linker based on the binuclear ruthenium complex can accurately construct two ruthenium centers in one molecule, completely avoiding the component competition and interface failure of the multi-molecule system, while achieving orthogonal control and dynamic reversibility, providing a molecular-level control basis for the dynamic reconstruction of complex structures. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a reversible coordination crosslinker and a wavelength / temperature orthogonal control method thereof. The reversible coordination crosslinker of the present invention solves the existing synergistic problems of multi-stimulus orthogonality, single-molecule functional integration and high cycle stability, and provides a new multi-stimulus orthogonal control strategy.

[0005] The reversible coordination cross-linking agent of the present invention has a structure as shown below:

[0006] .

[0007] The preparation method of the reversible coordination cross-linking agent of the present invention comprises the following steps:

[0008] Step 1: dissolving ruthenium trichloride and 4-carboxylic acid-2,2':6,2''-terpyridine in anhydrous ethanol, and reacting at 70-80°C for 4-8h; after the reaction, cooling to room temperature to obtain a suspension, filtering and collecting the precipitate, washing with ethanol and ether, and vacuum drying to obtain compound 1;

[0009] Step 2: Compound 1 and biquinoline (BiQ) were dissolved in a mixed solvent of anhydrous ethanol and deionized water, and the mixture was reacted in a nitrogen environment at 75-90°C in the dark for 18-36 hours; after the reaction, the mixture was filtered while hot, the filtrate was collected, and the crude product was obtained by rotary evaporation. The crude product was purified by silica gel column and vacuum dried to obtain compound 2;

[0010] Step 3: dissolving ethanolamine and potassium hydroxide in anhydrous dimethyl sulfoxide, stirring at 30-60°C for 30-60 min, adding 4-chloro-2,2':6,2''-terpyridine, and reacting at 30-60°C for 6-12 h; after the reaction is completed, cooling to room temperature, adding deionized water to the reaction solution, extracting the product with dichloromethane, and then washing with deionized water and saturated brine, collecting the organic phase, drying over anhydrous sodium sulfate, spin-drying to remove the solvent, and vacuum drying to obtain compound 3;

[0011] Step 4: Compound 3 and di-tert-butyl dicarbonate were dissolved in dichloromethane, and the mixture was reacted at 20-30°C for 2-6 hours. After the reaction, the mixture was washed with deionized water and saturated brine, and the organic phase was collected and dried over anhydrous sodium sulfate. The solvent was removed by spin drying, and the mixture was dried in vacuo to obtain compound 4.

[0012] Step 5: Compound 4 and ruthenium trichloride were dissolved in anhydrous ethanol, and the mixture was reacted at 70-80°C for 4-8h. After the reaction, the mixture was cooled to room temperature to obtain a suspension, and the precipitate was collected by suction filtration, and washed with ethanol and ether, and dried in vacuo to obtain compound 5.

[0013] Step 6: Compound 5, 2,2'-bipyridine (bpy), triethylamine and lithium chloride are dissolved in a mixed solvent of anhydrous ethanol and deionized water, and reacted in a nitrogen environment at 75-90°C in the dark for 4-12 hours; after the reaction is completed, the mixture is filtered while hot, the filtrate is collected, and the crude product is obtained by rotary evaporation. The crude product is purified by a neutral alumina column and vacuum dried to obtain compound 6;

[0014] Step 7: Compound 6 and trifluoroacetic acid were dissolved in dichloromethane, and the mixture was reacted at 20-30° C. for 1-4 h. After the reaction, the crude product was purified by a neutral alumina column and dried in vacuo to obtain compound 7;

[0015] Step 8: Under ice-water bath conditions, compound 2, triethylamine, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU) and 1-hydroxy-7-azabenzotriazole (HOAT) were dissolved in anhydrous dichloromethane, and the reaction was carried out for 30-60 min. Compound 7 was then added and the reaction was carried out at 20-30°C for 18-36 h. After the reaction, the crude product was purified by silica gel column and vacuum dried to obtain compound 8;

[0016] Step 9: Add compound 8 and silver tetrafluoroborate to a mixed solvent of deionized water and acetone, and react at 50-70°C for 12-24 hours. After the reaction, spin-dry the solvent, recrystallize in a sodium tetrafluoroborate aqueous solution, collect the solid by filtration, wash with dichloromethane and ether, and vacuum dry to obtain the target product 9.

[0017] In step 1, the molar ratio of ruthenium trichloride to 4-carboxylic acid-2,2':6,2''-terpyridine is 1:0.8-1.2.

[0018] In step 2, the molar ratio of compound 1 to diquinoline is 1:0.8-1.2.

[0019] In step 3, the molar ratio of 4-chloro-2,2':6,2''-terpyridine to ethanolamine is 1:1-10, and the molar ratio of 4-chloro-2,2':6,2''-terpyridine to potassium hydroxide is 1:2-10.

[0020] In step 4, the molar ratio of compound 3 to di-tert-butyl dicarbonate is 1:0.9-2.

[0021] In step 5, the molar ratio of compound 4 to ruthenium trichloride is 1:0.8-1.2.

[0022] In step 6, the molar ratio of compound 5 to 2,2'-bipyridine is 1:0.8-1.2, the molar ratio of compound 5 to triethylamine is 1:0.9-3, and the molar ratio of compound 5 to lithium chloride is 1:0.8-1.2.

[0023] In step 7, the molar ratio of compound 6 to trifluoroacetic acid is 1:20-100.

[0024] In step 8, the molar ratio of compound 2 to triethylamine is 1:0.9-3, the molar ratio of compound 2 to 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate is 1:0.9-2, the molar ratio of compound 2 to 1-hydroxy-7-azabenzotriazole is 1:0.9-2, and the molar ratio of compound 2 to compound 7 is 1:0.8-1.2.

[0025] In step 9, the molar ratio of compound 8 to silver tetrafluoroborate is 1:2-5.

[0026] The reaction route is as follows:

[0027] .

[0028] The wavelength / temperature orthogonal control method of the reversible coordination crosslinking agent of the present invention is to add acetonitrile as a ligand to the aqueous solution system of the reversible coordination crosslinking agent, coordinate the acetonitrile by adjusting the system temperature, and decoordinate the acetonitrile by adjusting the wavelength of the irradiated light, so as to realize light / heat induced ligand exchange.

[0029] The concentration of the reversible coordination cross-linking agent in the system is 1-4 mM, and the concentration of acetonitrile is 10-100 mM.

[0030] Preferably, the concentration of the reversible coordination cross-linking agent in the system is 3.7 mM, and the concentration of acetonitrile is 37 mM.

[0031] The wavelength / temperature orthogonal control method of the reversible coordination cross-linking agent of the present invention comprises the following steps:

[0032] A reversible coordination cross-linking agent and acetonitrile are added to deionized water, dissolved and mixed evenly; at 20-40°C, ruthenium containing Biq can coordinate with acetonitrile, while ruthenium containing bpy is difficult to coordinate with acetonitrile; at 70-90°C, all ruthenium can coordinate with acetonitrile; when the system is irradiated with light of a wavelength of 600nm-660nm, the acetonitrile ligand on the ruthenium containing Biq can dissociate, while the acetonitrile ligand on the ruthenium containing bpy cannot dissociate; when the system is irradiated with light of a wavelength of 440nm-500nm, all acetonitrile ligands on ruthenium can dissociate.

[0033] The ligand exchange reaction route of the reversible coordination cross-linking agent of the present invention is as follows:

[0034] .

[0035] When the ligand exchange of the reversible coordination cross-linking agent is regulated by temperature, the system temperature is controlled at 20-40°C, and the ruthenium connected to the biquinoline is coordinated with acetonitrile, so that the original water ligand is replaced by the acetonitrile ligand; the system temperature is controlled at 70-90°C, and all ruthenium is coordinated with acetonitrile, so that the original water ligand is replaced by the acetonitrile ligand.

[0036] Preferably, the system temperature is controlled at 25°C, and the ruthenium connected to the biquinoline is coordinated with acetonitrile, so that the original water ligand is replaced by the acetonitrile ligand; the system temperature is controlled at 80°C, and all ruthenium is coordinated with acetonitrile, so that the original water ligand is replaced by the acetonitrile ligand.

[0037] When the ligand exchange of the reversible coordination cross-linker is regulated by wavelength, the dissociation of the acetonitrile ligand on the ruthenium connected to the biquinoline is controlled by light with a wavelength of 600-660nm, and the dissociation of the acetonitrile ligand on all ruthenium is controlled by light with a wavelength of 440nm-500nm.

[0038] Preferably, a LED light source with a wavelength of 625 nm is used to control the dissociation of the acetonitrile ligand on ruthenium connected to bisquinoline, and a LED light source with a wavelength of 470 nm is used to control the dissociation of all acetonitrile ligands on ruthenium.

[0039] In order to more clearly describe the principle of the present invention, it is explained here that the reversible coordination cross-linking agent has two ruthenium coordination centers. The ruthenium containing biq can coordinate with acetonitrile at 25°C, so that the original water ligands are replaced by acetonitrile ligands, and the ruthenium containing bpy can coordinate with acetonitrile at 80°C, so that the original water ligands are replaced by acetonitrile ligands. The influence between them is small, and an orthogonal coordination interval can be formed; the acetonitrile on the ruthenium containing biq can be decoordinated by 625nm light, so that the original acetonitrile ligands are replaced by water ligands, and the acetonitrile on the ruthenium containing bpy can be decoordinated by 470nm light, so that the original acetonitrile ligands are replaced by water ligands, and an orthogonal decoordination interval can be formed, thereby realizing the thermal orthogonal coordination and photoorthogonal decoordination of the cross-linking agent of the present invention.

[0040] Compared with the prior art, the present invention provides a new compound containing two ruthenium centers in a single molecule, which can realize orthogonal control of multiple paths and provide a new orthogonal strategy. More likely, the acetonitrile ligand can be replaced by a cyano-containing ligand, thereby realizing orthogonal reversible control of the cross-linking and de-cross-linking of the polymer by light and heat, providing broader possibilities for realizing programmable control of dynamic networks. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 shows the reversible coordination cross-linker 1 H NMR spectroscopy.

[0042] Figure 2 The UV-visible absorption spectrum of the ligand exchange process ① is shown. Figure 2 It can be seen that the absorption peak around 550nm is blue-shifted, indicating that the water ligand on the ruthenium containing BiQ is replaced by the acetonitrile ligand, while the ruthenium containing bpy is not.

[0043] Figure 3 The UV-visible absorption spectrum of the ligand exchange process ② is shown. Figure 3 It can be seen that the absorption peak around 500 nm is red-shifted, indicating that the acetonitrile ligand on the ruthenium containing BiQ is replaced by a water ligand.

[0044] Figure 4 The UV-visible absorption spectrum of the ligand exchange process ③ is shown. Figure 4 It can be seen that the absorption peak around 500nm continues to blue-shift, indicating that the water ligand on the ruthenium containing bpy is replaced by the acetonitrile ligand.

[0045] Figure 5The UV-visible absorption spectrum of the ligand exchange process ④ is shown. Figure 5 It can be seen that the absorption peak position around 460nm remains unchanged, and the absorption peak around 500nm is red-shifted, indicating that the acetonitrile ligand on the ruthenium containing biq is replaced by a water ligand, while the ruthenium containing bpy is not.

[0046] Figure 6 The UV-visible absorption spectrum of the ligand exchange process ⑤ is shown. Figure 6 It can be seen that the absorption peak around 550nm is blue-shifted, indicating that the water ligand on the ruthenium containing BiQ is replaced by the acetonitrile ligand.

[0047] Figure 7 The UV-visible absorption spectrum of the ligand exchange process ⑥ is shown. Figure 7 It can be seen that the absorption peak around 460nm is red-shifted, indicating that the acetonitrile ligand on the ruthenium containing bpy is replaced by a water ligand.

[0048] Figure 8 The UV-visible absorption spectrum of the ligand exchange process ⑦ is shown. Figure 8 It can be seen that the absorption peaks around 460nm and 500nm are red-shifted, indicating that the acetonitrile ligands on the ruthenium containing BiQ and Bpy are replaced by water ligands.

[0049] Fig. 9 The UV-visible absorption spectrum of the ligand exchange process ⑧ is shown. Fig. 9 It can be seen that the absorption peaks around 550nm and 500nm are blue-shifted, indicating that the water ligands on the ruthenium containing BiQ and Bpy are replaced by acetonitrile ligands.

[0050] Fig.10 The reversible cycle results of the reversible coordination cross-linking agent are shown, where Figure A is the cycle chemical reaction formula and Figure B is the cycle 1 H NMR spectrum, Figure C shows the proportion of cyclic ruthenium-acetonitrile bonds to the total ruthenium. Fig.10 It can be seen that in the 10 cycles taking the ligand exchange process ⑦⑧ as an example, the proportion of ruthenium-acetonitrile bonds did not change significantly with the increase in the number of cycles, reflecting good reversible cycle stability. DETAILED DESCRIPTION

[0051] In order to further illustrate the present invention, the method provided by the present invention is described in detail below in conjunction with the embodiments. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than for limiting the present invention.

[0052] Example 1: Synthesis of reversible coordination cross-linker

[0053] 1. Synthesis of Compound 1

[0054] Ruthenium trichloride (784.41 mg, 3.00 mmol) and 4-carboxylic acid-2,2':6,2''-terpyridine (831.84, 3.00 mmol) were dissolved in anhydrous ethanol (30 mL) and reacted at 80 °C for 6 h. After the reaction, the suspension was cooled to room temperature to obtain a suspension, which was filtered and the precipitate was collected and washed with ethanol and ether. After vacuum drying, a brown-yellow solid (1.29 g, yield 86%) was obtained, namely compound 1.

[0055] 2. Synthesis of Compound 2

[0056] Compound 1 (751.13 mg, 1.50 mmol) and diquinoline (384.47 mg, 1.50 mmol) were dissolved in a mixed solvent of anhydrous ethanol (60 mL) and deionized water (20 mL), and reacted in a nitrogen environment at 85 ° C in the dark for 24 h; after the reaction, the mixture was filtered while hot, the filtrate was collected, and the crude product was obtained by rotary evaporation. The crude product was purified by silica gel column (eluent: dichloromethane / methanol = 10 / 1), and vacuum dried to obtain a blue-purple solid (656.17 mg, yield 62%), namely compound 2.

[0057] 3. Synthesis of Compound 3

[0058] Ethanolamine (305.42 mg, 5 mmol) and potassium hydroxide (1.40 g, 25 mmol) were dissolved in anhydrous dimethyl sulfoxide (10 mL). After stirring at 40 °C for 30 min, 4-chloro-2,2':6,2''-terpyridine (1.34 g, 5 mmol) was added and reacted at 40 °C for 9 h. After the reaction was completed, the mixture was cooled to room temperature, deionized water was added to the reaction solution, the product was extracted with dichloromethane, and then washed with deionized water and saturated brine. The organic phase was collected, dried over anhydrous sodium sulfate, the solvent was removed by spin drying, and vacuum dried to obtain a light yellow liquid (1.36 g, yield 93%), i.e., compound 3.

[0059] 4. Synthesis of Compound 4

[0060] Compound 3 (1.17 g, 4 mmol) and di-tert-butyl dicarbonate (873.00 mg, 4 mmol) were dissolved in dichloromethane (20 mL) and reacted at 25 °C for 4 h. After the reaction, the mixture was washed with deionized water and saturated brine. The organic phase was collected, dried over anhydrous sodium sulfate, and the solvent was removed by spin drying. After vacuum drying, a white solid (1.48 g, yield 94%) was obtained, namely compound 4.

[0061] 5. Synthesis of Compound 5

[0062] Compound 4 (1.18 g, 3.00 mmol) and ruthenium trichloride (784.41 mg, 3.00 mmol) were dissolved in anhydrous ethanol (30 mL) and reacted at 80 °C for 6 h. After the reaction, the suspension was cooled to room temperature to obtain a suspension, which was filtered and the precipitate was collected and washed with ethanol and ether. After vacuum drying, a brown-yellow solid (1.49 g, yield 83%) was obtained, namely compound 5.

[0063] 6. Synthesis of Compound 6

[0064] Compound 5 (1.20 g, 2 mmol), 2,2'-bipyridine (312.38 mg, 2 mmol), triethylamine (556 μL, 4.00 mmol) and lithium chloride (89.02 mg, 2.10 mmol) were dissolved in a mixed solvent of anhydrous ethanol (75 mL) and deionized water (25 mL), and reacted in a nitrogen environment at 85 °C in the dark for 12 h; after the reaction, the reaction was filtered while hot, the filtrate was collected, and the crude product was obtained by rotary evaporation. The crude product was purified by a neutral alumina column (eluent: dichloromethane / methanol = 10 / 1), and vacuum dried to obtain a purple-red solid (850.33 mg, yield 50%), i.e., compound 6.

[0065] 7. Synthesis of Compound 7

[0066] Compound 6 (720.62 mg, 1 mmol) and trifluoroacetic acid (4.46 mL, 60 mmol) were dissolved in dichloromethane (5 mL) and reacted at 25 °C for 2 h. After the reaction, the crude product was purified by a neutral alumina column (eluent: dichloromethane / methanol = 6 / 1) and vacuum dried to obtain a purple-red solid (570.86 mg, yield 92%), namely compound 7.

[0067] 8. Synthesis of Compound 8

[0068] In an ice-water bath, compound 2 (70.56 mg, 0.10 mmol), triethylamine (28 μL, 0.20 mmol), 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate (57.04 mg, 0.15 mmol) and 1-hydroxy-7-azabenzotriazole (20.42 mg, 0.15 mmol) were dissolved in anhydrous dichloromethane (5 mL) and reacted for 60 min. Compound 7 (62.05 mg, 0.1 mmol) was then added and reacted at 25 °C for 24 h. After the reaction, the crude product was purified by silica gel column (eluent: dichloromethane / methanol = 10 / 1) and dried in vacuo to obtain a purple solid (60.17 mg, yield 46%), i.e., compound 8.

[0069] 9. Synthesis of reversible coordination crosslinker, compound 9

[0070] Compound 8 (52.32 mg, 0.04 mmol) and silver tetrafluoroborate (19.47 mg, 0.10 mmol) were added to a mixed solvent of deionized water (5 mL) and acetone (5 mL), and the mixture was reacted at 60 °C for 12 h. After the reaction, the solvent was dried by spin drying, and the mixture was recrystallized in a saturated aqueous solution of sodium tetrafluoroborate. The solid was collected by filtration, washed with dichloromethane and ether, and dried in vacuo to obtain a red solid (47.10 mg, yield 76%), which is the reverse coordination crosslinker compound 9. The NMR spectrum is shown in Figure 1 .

[0071] Example 2: UV-Vis spectroscopy test of reversible coordination crosslinker

[0072] 1. Ligand exchange process①

[0073] Compound 9 (11.47 mg, 0.0074 mmol) and acetonitrile (4 μL, 0.074 mmol) were added to deionized water (2 mL) to prepare solution A with a ruthenium complex concentration of 3.7 mM. The solution was placed in a constant temperature water bath at 25°C. The solution was then tested for UV-visible absorption spectrum using a UV-visible spectrophotometer. The wavelength range of the test scan was 370 nm-750 nm. As the placement time increased, the UV-visible absorption spectrum was tested again at regular intervals. Finally, solution B was obtained, as shown in FIG. Figure 2 shown.

[0074] 2. Ligand exchange process②

[0075] Solution B was illuminated by an LED lamp with a wavelength of 625 nm (light intensity 10 mW / cm 2 ) irradiation, and then use UV-visible spectrophotometer to test the UV-visible absorption spectrum of the solution. The wavelength range of the test scan is 370nm-750nm. As the irradiation time increases, the UV-visible absorption spectrum is tested again at regular intervals. Figure 3 shown.

[0076] 3. Ligand exchange process③

[0077] Solution B was placed in a constant temperature water bath at 80°C, and then the solution was tested for UV-visible absorption spectrum using a UV-visible spectrophotometer. The wavelength range of the test scan was 370nm-750nm. As the placement time increased, the UV-visible absorption spectrum was tested again at regular intervals to obtain solution C. Figure 4 shown.

[0078] 4. Ligand exchange process④

[0079] Solution C was illuminated by an LED lamp with a wavelength of 625 nm (light intensity 10 mW / cm 2) irradiation, and then the solution is tested for UV-visible absorption spectrum using a UV-visible spectrophotometer, the test scanning wavelength range is 370nm-750nm, and as the irradiation time increases, the UV-visible absorption spectrum is tested again at regular intervals, and finally a solution D is obtained, such as Figure 5 shown.

[0080] 5. Ligand exchange process⑤

[0081] Solution D was placed in a 25°C constant temperature water bath, and then the UV-visible absorption spectrum of the solution was tested using a UV-visible spectrophotometer. The wavelength range of the test scan was 370nm-750nm. As the placement time increased, the UV-visible absorption spectrum was tested again at regular intervals. Figure 6 shown.

[0082] 6. Ligand exchange process⑥

[0083] Solution D was illuminated by an LED lamp with a wavelength of 470 nm (light intensity 50 mW / cm 2 ) irradiation, and then use UV-visible spectrophotometer to test the UV-visible absorption spectrum of the solution. The wavelength range of the test scan is 370nm-750nm. As the irradiation time increases, the UV-visible absorption spectrum is tested again at regular intervals. Figure 7 shown.

[0084] 7. Ligand exchange process ⑦

[0085] Solution A was placed in a constant temperature water bath at 80°C, and then the UV-visible absorption spectrum of the solution was tested using a UV-visible spectrophotometer. The wavelength range of the test scan was 370nm-750nm. As the placement time increased, the UV-visible absorption spectrum was tested again at regular intervals. Figure 8 shown.

[0086] 8. Ligand exchange process⑧

[0087] Solution C was illuminated by an LED lamp with a wavelength of 470 nm (light intensity 50 mW / cm 2 ) irradiation, and then use UV-visible spectrophotometer to test the UV-visible absorption spectrum of the solution. The wavelength range of the test scan is 370nm-750nm. As the irradiation time increases, the UV-visible absorption spectrum is tested again at regular intervals. Fig. 9 shown.

[0088] Example 3: Reversible Cycle of Reversible Coordination Crosslinker 1 H NMR spectroscopy

[0089] Compound 9 (1.39 mg, 0.0009 mmol) and acetonitrile (2 μL, 0.036 mmol) were added to deionized water (0.6 mL) to prepare a solution with a ruthenium complex concentration of 1.5 mM. The solution was added to an NMR tube and placed in a constant temperature water bath at 80 °C for about 1 h to complete the coordination. The solution was then illuminated with an LED light with a wavelength of 470 nm (light intensity 50 mW / cm 2 ) irradiate for about 20 minutes to completely de-coordinate. Repeat 10 times. 1 The ligand exchange yield was tested by H NMR spectroscopy. Fig.10 shown.

[0090] The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be noted that for those of ordinary skill in the art, without departing from the principles of the present invention, several improvements and modifications may be made to the present invention, and these improvements and modifications also fall within the scope of protection of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A reversible coordination cross-linking agent, characterized in that Its structure is as follows: 。 2. The method for preparing the reversible coordination crosslinking agent according to claim 1, characterized in that The steps include: Step 1: dissolving ruthenium trichloride and 4-carboxylic acid-2,2':6,2''-terpyridine in anhydrous ethanol, and reacting at 70-80°C for 4-8h; after the reaction, cooling to room temperature to obtain a suspension, and separating and purifying to obtain compound 1; Step 2: dissolving compound 1 and biquinoline in a mixed solvent of anhydrous ethanol and deionized water, and reacting in a nitrogen environment at 75-90° C. in the dark for 18-36 hours; after the reaction, separating and purifying to obtain compound 2; Step 3: dissolving ethanolamine and potassium hydroxide in anhydrous dimethyl sulfoxide, stirring at 30-60°C for 30-60 min, adding 4-chloro-2,2':6,2''-terpyridine, and reacting at 30-60°C for 6-12 h; after the reaction, separating and purifying to obtain compound 3; Step 4: dissolving compound 3 and di-tert-butyl dicarbonate in dichloromethane, reacting at 20-30° C. for 2-6 hours, and separating and purifying after the reaction to obtain compound 4; Step 5: dissolving compound 4 and ruthenium trichloride in anhydrous ethanol, and reacting at 70-80°C for 4-8h; separating and purifying after the reaction to obtain compound 5; Step 6: dissolving compound 5, 2,2'-bipyridine, triethylamine and lithium chloride in a mixed solvent of anhydrous ethanol and deionized water, and reacting in a nitrogen environment at 75-90° C. in the dark for 4-12 hours; after the reaction, separating and purifying to obtain compound 6; Step 7: dissolving compound 6 and trifluoroacetic acid in dichloromethane, reacting at 20-30° C. for 1-4 h, and separating and purifying after the reaction to obtain compound 7; Step 8: Dissolve compound 2, triethylamine, 2-(7-azabenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate and 1-hydroxy-7-azabenzotriazole in anhydrous dichloromethane in an ice-water bath, react for 30-60 min, add compound 7, react at 20-30° C. for 18-36 h, separate and purify after the reaction to obtain compound 8; Step 9: Add compound 8 and silver tetrafluoroborate to a mixed solvent of deionized water and acetone, react at 50-70° C. for 12-24 hours, separate and purify after the reaction to obtain the target product 9; The reaction route is as follows: 。 3. The wavelength / temperature orthogonal control method of the reversible coordination crosslinker according to claim 1, characterized in that: Acetonitrile is added as a ligand to the aqueous solution system of the reversible coordination crosslinking agent, the acetonitrile is coordinated by adjusting the system temperature, and the acetonitrile is decoordinated by adjusting the wavelength of the irradiated light to achieve photo / thermal ligand exchange.

4. The wavelength / temperature orthogonal control method according to claim 3, characterized in that: The concentration of the reversible coordination cross-linking agent in the system is 1-4 mM, and the concentration of acetonitrile is 10-100 mM.

5. The wavelength / temperature orthogonal control method according to claim 4, characterized in that: The concentration of the reversible coordination cross-linking agent in the system is 3.7 mM, and the concentration of acetonitrile is 37 mM.

6. The wavelength / temperature orthogonal control method according to claim 4, characterized in that: When the ligand exchange of the reversible coordination cross-linking agent is regulated by temperature, the system temperature is controlled at 20-40°C, and the ruthenium connected to the biquinoline is coordinated with acetonitrile, so that the original water ligand is replaced by the acetonitrile ligand; the system temperature is controlled at 70-90°C, and all ruthenium is coordinated with acetonitrile, so that the original water ligand is replaced by the acetonitrile ligand.

7. The wavelength / temperature orthogonal control method according to claim 6, characterized in that: When the ligand exchange of the reversible coordination cross-linker is regulated by wavelength, the dissociation of the acetonitrile ligand on the ruthenium connected to the biquinoline is controlled by light with a wavelength of 600-660nm, and the dissociation of the acetonitrile ligand on all ruthenium is controlled by light with a wavelength of 440nm-500nm.

8. The wavelength / temperature orthogonal control method according to claim 6 or 7, characterized in that The ligand exchange reaction route of the reversible coordination cross-linking agent is as follows: 。

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