Pillararene-based photo-responsive MOF-based ion-gated nanochannel and preparation method thereof

Abstract

The present application relates to the technical field of biological materials, and particularly relates to a pillar arene-based photoresponsive MOF-based ion gate nano-channel and a preparation method thereof. The pillar arene-based photoresponsive MOF-based ion gate nano-channel is prepared by taking PET as a substrate to prepare a bullet-shaped nano-channel, the substrate can provide structural support; taking a pillar arene-based P5A-MOF-1 as a core functional layer, the functional layer can provide a stable cavity environment; filling an organic aromatic azo compound in the cavity of the P5A-MOF-1 to realize a photoresponsive structural change. The effective volume of the cavity of the P5A-MOF-1 is regulated through photoisomerization of the azo group, and then precise gating of ion transmission is achieved. The preparation method is simple in operation, mild and controllable in conditions, and is conducive to large-scale production.

Description

Technical Field

[0001] This invention relates to the field of biomaterials technology, and in particular to photoresponsive MOF-based ion-gated nanochannels based on columnar aromatic hydrocarbons and their preparation methods. Background Technology

[0002] Ion-gated nanochannels, as functional nanostructures, possess sub-nanometer to nanometer-scale pore sizes and can respond to external stimuli such as voltage, ligands, light, and mechanical forces, thereby precisely controlling the transmembrane or transmedium transport of ions. With their atomic-level ion recognition capabilities and controllable transport characteristics, ion-gated nanochannels have irreplaceable application value in biomedical detection, efficient ion separation, energy conversion devices, and biomimetic ion-electronic interfaces, and have become a research hotspot in the interdisciplinary field of materials science, nanoengineering, and biomedicine.

[0003] Currently, significant progress has been made in the construction and regulation of ion-gated nanochannels. In terms of material systems, various functional systems have been developed, including MXene-based conductive nanochannels, metal-organic framework (MOF)-based hierarchical nanochannels, rotaxane-structured dynamic nanochannels, and conjugated microporous polymer photoresponsive nanochannels. Regarding regulation mechanisms, through surface functionalization and structural design, various gating modes have been achieved, such as voltage-ion charge synergistic regulation, photo-induced isomerization-driven regulation, and ion-induced conformational switching. However, existing ion-gated nanochannel technologies still face several challenges, primarily in the following aspects:

[0004] First, there is an imbalance between ion control precision and gating efficiency. Leakage current is significant when most channels are closed, resulting in insufficient ability to accurately distinguish ions with sub-nanometer size differences. The gating switching ratio of some photoresponse systems is relatively low, making it difficult to meet the requirements of high-precision applications.

[0005] Secondly, their structural stability is poor. Under physiological environments or complex working conditions, MOF-based channels are prone to crystal shedding due to light irradiation and ion erosion, while protein-modified channels are prone to surface functional layer degradation, resulting in significant performance degradation after repeated use.

[0006] Third, the collaborative control mechanism is imperfect. In most systems, the synergy between the channel framework and the response unit is weak, and there is a lack of a spatially constrained environment that can be precisely controlled, resulting in insufficient sensitivity and controllability of the gating response.

[0007] The aforementioned problems are particularly prominent in the important field of photoresponsive MOF-based ion-gated nanochannels. Traditional MOF-based nanochannels suffer from weak interfacial interactions between the framework and photoresponsive molecules, as well as insufficient spatial confinement effects, making it difficult to establish efficient gating mechanisms. This further exacerbates technical defects such as low on / off ratios, poor reversibility, and insufficient stability, becoming the main factors restricting the practical application of this type of nanochannel.

[0008] Therefore, in order to address the aforementioned technical shortcomings of existing ion-gated nanochannels, the development of ion-gated nanochannel technology that combines high ion selectivity, high environmental stability, and precise controllability has become a core requirement for promoting its industrial application in fields such as biomedical detection and high-efficiency energy conversion. Summary of the Invention

[0009] This invention aims to at least solve one of the technical problems existing in related technologies. Therefore, the first objective of this invention is to provide a method for preparing photoresponsive MOF-based ion-gated nanochannels based on columnar aromatics; the second objective of this invention is to provide photoresponsive MOF-based ion-gated nanochannels based on columnar aromatics.

[0010] To achieve the first objective, the technical solution adopted by this invention is as follows:

[0011] The preparation method of photoresponsive MOF-based ion-gated nanochannels based on columnar aromatic hydrocarbons includes the following steps:

[0012] S100. The columnar aromatic hydrocarbon and soluble zinc salt I are dispersed in a polar organic solvent, and a solvothermal reaction is used to induce a coordination reaction between the two to prepare P5A-MOF-1.

[0013] S200: Bullet-shaped nanochannels were fabricated using a PET film as a substrate and a double-sided differential etching process.

[0014] PET stands for polyethylene terephthalate.

[0015] The aforementioned dual-sided differential etching refers to using etching solvents with different etching rates on both sides of the PET film;

[0016] S300. The thin end of the bullet-shaped nanochannel was perfused with an organic ligand precursor solution, and the thick end of the bullet-shaped nanochannel was perfused with a metal source precursor solution. The photoresponsive MOF-based ion-gated nanochannel based on columnar aromatic hydrocarbons was prepared by reverse diffusion interface synthesis.

[0017] The organic ligand precursor solution is an organic solution I containing P5A-MOF-1 and an organic aromatic azo compound, and the metal source precursor solution is an organic solution II containing a soluble zinc salt II.

[0018] The structural formula of the columnar aromatic hydrocarbon is shown below:

[0019] n is selected from 3, 4 and 5.

[0020] Columnar aromatics, as a class of macrocyclic compounds with electron-rich cavities, can achieve molecular recognition and regulation through host-guest interactions. Meanwhile, organic aromatic azo compounds possess reversible photoisomerization properties. The synergistic integration of these two provides a new approach for constructing highly efficient ion-gated channels. This invention uses PET as a substrate to prepare bullet-shaped nanochannels, which provides structural support. A columnar aromatic metallofibrils (MOFs) are used as the core functional layer, providing a stable cavity environment. Organic aromatic azo compounds are filled into the MOF cavity to achieve photoresponsive structural changes. The effective volume of the MOF cavity is controlled through the photoisomerization of the azo groups, thereby achieving precise gating of ion transport.

[0021] Preferably, in step S100, the structural formula of the columnar aromatic hydrocarbon is as follows:

[0022] ;

[0023] The synthesis of the columnar aromatic hydrocarbons includes the following steps:

[0024] S110, Utilization P5A-MeO was synthesized by reacting with paraformaldehyde, and its structural formula is shown below:

[0025] ;

[0026] S120. P5A-Q was synthesized by reacting P5A-MeO with ammonium nitrate, and its structural formula is shown below:

[0027] ;

[0028] S130. Using the selective reduction reaction of the quinone group of P5A-Q, P5A-OH was synthesized, with the following structural formula:

[0029] ;

[0030] S140. P5A-OH was activated using an activating agent, followed by the addition of trifluoromethanesulfonic anhydride to induce a nucleophilic substitution reaction, synthesizing P5A-OTf, with the structural formula shown below:

[0031] ;

[0032] Wherein, Tf is trifluoromethanesulfonyl;

[0033] S150. P5A-COOCH3 was synthesized by cross-coupling reaction of P5A-OTf with arylboronic acid, and its structural formula is shown below:

[0034] ;

[0035] S160, using the hydrolysis reaction of P5A-COOCH3 under alkaline conditions, the columnar aromatic hydrocarbon was synthesized.

[0036] Preferably, in step S130, the reducing agent used for the selective reduction reaction of quinone groups is Na2S2O4;

[0037] And / or in step S140, the activator is selected from pyridine;

[0038] And / or in step S150, the arylboronic acid is selected from 4-methoxycarbonylphenylboronic acid.

[0039] Preferably, in step S100, the soluble zinc salt I is selected from zinc nitrate hexahydrate, and the mass ratio of the columnar aromatic hydrocarbon to the soluble zinc salt I is 2:3 to 3:2;

[0040] And / or the polar organic solvent is selected from N,N-dimethylformamide (DMF).

[0041] Preferably, in step S100, the temperature of the solvothermal reaction is 90℃~110℃, and the reaction time is 18h~30h.

[0042] Preferably, in step S200, the process of the dual-sided differential etching process is as follows:

[0043] A PET film is placed in an etching apparatus, with one side of the PET film in contact with a composite etchant consisting of an alkaline chemical etchant I and an anionic surfactant, and the other side of the PET film in contact with an alkaline chemical etchant II. The etching is carried out at 50℃~70℃ for 150s~250s, and then the etching is terminated to obtain bullet-shaped nanochannels.

[0044] Preferably, both alkaline chemical etchant I and alkaline chemical etchant II are selected from NaOH aqueous solution, and the anionic surfactant is selected from 0.025% sodium dodecyl diphenyl ether disulfonate.

[0045] Preferably, during the etching process, the change in the ion current of the etching solution is monitored by applying a transmembrane voltage, and the etching is terminated when the ion current reaches 60nA to 70nA.

[0046] Preferably, in step S300, the organic aromatic azo compound is selected from azobenzene (AZO), and the mass ratio of AZO to P5A-MOF-1 is 3:20 to 1:5;

[0047] The soluble zinc salt II is selected from zinc nitrate hexahydrate;

[0048] The solvents for both organic solution I and organic solution II are selected from DMF.

[0049] To achieve the second objective, the technical solution adopted by this invention is as follows:

[0050] Photoresponsive MOF-based ion-gated nanochannels based on columnar aromatics are prepared using any one of the above-described methods, including:

[0051] Bullet-shaped nanochannels, which serve as structural supports;

[0052] P5A-MOF-1, P5A-MOF-1 is grown in bullet-shaped nanochannels;

[0053] An organic aromatic azo compound, wherein the organic aromatic azo compound is filled within the cavity of P5A-MOF-1.

[0054] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0055] This invention provides a photoresponsive MOF-based ion-gated nanochannel based on columnar aromatics and its preparation method. The photoresponsive MOF-based ion-gated nanochannel is prepared using a bullet-shaped nanochannel on a PET substrate, which provides structural support. P5A-MOF-1, based on columnar aromatics, serves as the core functional layer, providing a stable cavity environment. Organic aromatic azo compounds are filled into the P5A-MOF-1 cavity to achieve photoresponsive structural changes. The effective volume of the P5A-MOF-1 cavity is controlled through the photoisomerization of the azo groups, thereby achieving precise gating of ion transport. The test results show that the ion-gated nanochannel provided by this invention has a significant gating effect, with an on / off ratio of 633.6 at a bias voltage of -2V, which is far superior to that of traditional MOF-based channels. It also has excellent photoresponse reversibility, and can achieve multiple stable on-off cycles under alternating UV irradiation (365nm, 25min) and solar recovery (2h). The ion flux under each gated state does not decrease significantly, and the P5A-MOF-1 crystal structure is not damaged after UV irradiation and solar recovery cycles.

[0056] The preparation method provided by this invention is simple to operate, with mild and controllable conditions, which is conducive to large-scale production.

[0057] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0058] Figure 1 This is the P5A-COOH hydrogen nuclear magnetic resonance spectrum provided in Example 1 of the present invention.

[0059] Figure 2 This is a schematic diagram of the reaction tank provided in Embodiment 4 of the present invention.

[0060] Figure 3 This is a scanning electron microscope (SEM) cross-sectional image of the distributed PET-P5A-MOF-1-AZO bullet-shaped nanochannel PET membrane provided in Embodiment 4 of the present invention.

[0061] Figure 4 The X-ray diffraction (XRD) patterns of P5A-MOF-1, P5A-MOF-1-AZO, PET-P5A-MOF-1, and PET-P5A-MOF-1-AZO provided in Embodiment 4 of the present invention are shown.

[0062] Figure 5 The Fourier Transform Infrared Spectroscopy (FTIR) spectra of P5A-COOH, P5A-MOF-1, P5A-MOF-1-AZO, and AZO provided in Embodiment 4 of the present invention are shown.

[0063] Figure 6 The XRD patterns of MOF-5, MOF-5-AZO, PET-MOF-5, and PET-MOF-5-AZO provided in Embodiment 4 of the present invention are shown.

[0064] Figure 7 This is a graph showing the results of ion current testing (bias voltage of -2V) on PET film, PET-P5A-MOF-1-AZO and PET-P5A-MOF-1-AZO provided in Embodiment 4 of the present invention.

[0065] Figure 8 This is a graph showing the results of ion current testing (bias voltage of -2V) on PET-P5A-MOF-1-AZO and PET-MOF-5-AZO provided in Embodiment 4 of the present invention.

[0066] Figure 9 This is a graph showing the test results of the electrochemical switching performance of the PET-P5A-MOF-1-AZO nanochannel under alternating UV irradiation (365nm, 25min) and sunlight recovery (2h) conditions provided in Example 4 of the present invention.

[0067] Figure 10The image shows the XRD pattern of the P5A-MOF-1-AZO nanochannel after four cycles of alternating UV (365nm) irradiation and sunlight irradiation (2h) provided in this embodiment of the invention. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.

[0069] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, unless otherwise specified, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0070] Example 1

[0071] Columnar aromatics The preparation of [the substance] is shown in the following synthetic route:

[0072] ;

[0073] Its synthesis process is as follows:

[0074] I. Synthesis of P5A-MeO.

[0075] 1,4-Dimethoxybenzene (10.00 g, 72.37 mmol) and paraformaldehyde (10.86 g, 362 mmol) were added to CH2Cl2 (200 mL). After stirring at 20–30 °C for 1.5–2 h, BF3·OEt2 (9.44 mL) was added dropwise and stirring was continued for 1 h. The mixture was quenched with methanol and purified by silica gel column chromatography to obtain P5A-MeO.

[0076] The eluent for silica gel column chromatography is a mixed solvent of petroleum ether (PE) and dichloromethane (CH2Cl2), with a volume ratio of PE to CH2Cl2 of 1:2.

[0077] II. Synthesis of P5A-Q.

[0078] P5A-MeO (5.00 g, 6.67 mmol) was dissolved in CH2Cl2 (100 mL), and cerium ammonium nitrate (7.3 g, 13.33 mmol) aqueous solution was added dropwise at room temperature. The mixture was stirred for 30 min, extracted with CH2Cl2, washed with saturated NaCl aqueous solution, dried over MgSO4, and purified by silica gel column chromatography to obtain P5A-Q.

[0079] The eluent for silica gel column chromatography is a mixed solvent composed of petroleum ether (PE) and dichloromethane (CH2Cl2), with a volume ratio of PE to CH2Cl2 of 1:1.

[0080] III. Synthesis of P5A-OH.

[0081] Under a nitrogen atmosphere, P5A-Quinone (2g, 2.86mmol) and Na2S2O4 (11g, 64.18mmol) were dissolved in a mixed solvent of CH2Cl2 (80mL) / water (40mL), stirred for 12–18 h, extracted with CH2Cl2, dried with Na2SO4, and concentrated to obtain P5A-OH.

[0082] IV. Synthesis of P5A-OTf.

[0083] Under a nitrogen atmosphere, P5A-OH (2 g, 2.86 mmol) and pyridine (4.00 mL, 50.0 mmol) were added to anhydrous CH2Cl2 (80 mL), cooled to 0 °C, and Tf2O (8.00 mL, 48.0 mmol) was added dropwise. After the addition was complete, the temperature was raised to room temperature and stirred for 10–14 h. The mixture was washed with water to separate the layers, washed with saturated NaCl aqueous solution, dried over Na2SO4, and purified by silica gel column chromatography to obtain P5A-OTf.

[0084] The eluent for silica gel column chromatography is a mixed solvent composed of PE and CH2Cl2 in a volume ratio of 1:1.

[0085] V. Synthesis of P5A-COOCH3.

[0086] P5A-OTf (1.00 g, 1.01 mmol), 4-(methoxycarbonyl)phenylboronic acid (1.00 g, 5.55 mmol), 13 mg / mL sodium carbonate aqueous solution (30 mL), and anhydrous tetrahydrofuran (50 mL) were added sequentially to a dry three-necked flask. After stirring, Pd(PPh3)4 (180 mg, 0.160 mmol) was added. The mixture was heated to 80°C and stirred for 24 h. After cooling to room temperature, dichloromethane (200 mL) was added for extraction. The organic phase was collected after standing and separating into layers. The organic phase was washed sequentially with deionized water (30 mL) and dilute hydrochloric acid (30 mL), dried over anhydrous Na2SO4, and purified by silica gel column chromatography to obtain P5A-COOCH3.

[0087] The eluent for silica gel column chromatography is a mixed solvent composed of CH2Cl2 and CH3OH, with a volume ratio of 1:1.

[0088] VI. Synthesis of P5A-COOH.

[0089] The P5A-COOCH3 obtained in the previous steps was added to THF (25 mL), followed by 0.5 M sodium hydroxide aqueous solution (25 mL). The mixture was heated to 50°C and stirred for 12 minutes. After cooling to room temperature and removing the organic solvent under vacuum, the pH was adjusted to 3 with 10% hydrochloric acid. A large amount of precipitate was produced in the solution. The precipitate was collected by filtration to obtain P5A-COOH. Its proton nuclear magnetic resonance spectrum is shown below. Figure 1 As shown.

[0090] Example 2

[0091] I. Synthesis of P5A-MOF-1 bulk powder.

[0092] P5A-COOH (20 mg) and Zn(NO3)2·6H2O (20 mg) were dispersed in anhydrous DMF (2.5 mL). The mixture was heated to 100 °C and reacted for 24 hours. The mother liquor was discarded, and the crystals at the bottom were retained. Acetone (5 mL) was added to the crystals, and the acetone was changed daily for 3 days. The crystals were then transferred to a supercritical CO2 dryer and cooled to 0 °C. Ultra-high purity liquid CO2 (purity ≥99.999%) was then introduced into the chamber through a siphon tube for drying, resulting in P5A-MOF-1 bulk powder.

[0093] 2. Synthesis of MOF-5 bulk powder.

[0094] In a 100 mL polytetrafluoroethylene-lined high-pressure reactor, Zn(NO3)2·6H2O (1.664 g) and terephthalic acid (H2BDC) (0.352 g) were dissolved in DMF (80 mL). After sealing, the mixture was heated to 130 °C and reacted for 4 h. After cooling to room temperature, the precipitate was collected by centrifugation. The powder precipitate was washed with DMF until the upper washing liquid was colorless and transparent to remove unreacted zinc nitrate. The washed precipitate was transferred to a dry beaker, methanol (30 mL) was added, and the mixture was shaken to disperse and then allowed to stand for soaking. Fresh methanol (30 mL each time) was replaced once a day for 3 days. Then, the mixture was dried overnight under vacuum at 160 °C to obtain MOF-5 bulk powder.

[0095] Example 3

[0096] The process for preparing bullet-shaped PET nanochannels is as follows:

[0097] Bullet-shaped PET nanochannels were prepared using a combination of trajectory etching technology and surfactant-controlled etching. The process is as follows:

[0098] One side of the PET film was placed in an etching solution composed of NaOH aqueous solution (6M) and sodium dodecyl diphenyl ether disulfonate (0.025wt%), and the other side was placed in NaOH aqueous solution (6M). The etching temperature was set to 60℃. During the etching process, a transmembrane voltage of 1V was applied to monitor the ion current. When the current reached about 65nA (for about 200s), the etching solution was removed and a stop solution (a mixed stop solution composed of 1M potassium chloride and 1M formic acid) was added to terminate the etching, resulting in bullet-shaped nanochannels distributed on the PET film.

[0099] Example 4

[0100] Bullet-shaped nanochannels modified with P5A-MOF-1, P5A-MOF-1-AZO, MOF-5, and MOF-5-AZO, respectively, were prepared by a reverse diffusion interfacial synthesis method and are designated as PET-P5A-MOF-1, PET-P5A-MOF-1-AZO, PET-MOF-5, and PET-MOF-5-AZO, respectively. The preparation process is described below:

[0101] A PET membrane with bullet-shaped nanochannels is immersed in a polytetrafluoroethylene reaction chamber, which is then divided into two chambers by the PET membrane. Figure 2 As shown, P5A-MOF-1, P5A-MOF-1-AZO, MOF-5 and MOF-5-AZO precursor solutions were added and reacted, then washed three times with ethanol and dried overnight at room temperature to obtain modified bullet-shaped nanochannels.

[0102] I. The process parameters for PET-P5A-MOF-1 bullet-shaped nanochannels are as follows:

[0103] P5A-MOF-1 precursor solution: The tip side is a mixed solution of P5A-COOH (20mg) and DMF (2.5mL), and the base side is a mixed solution of Zn(NO3)2·6H2O (20mg) and DMF (2.5mL);

[0104] Reaction conditions and time: Reaction at 100℃ for 24 hours.

[0105] II. The process parameters for PET-P5A-MOF-1-AZO bullet-shaped nanochannels are as follows:

[0106] P5A-MOF-1-AZO precursor solution: The tip side is a mixed solution of P5A-COOH (20 mg), AZO (3.87 mg), and DMF (5.0 mL), and the base side is a mixed solution of Zn(NO3)2·6H2O (20 mg), AZO (3.87 mg), and DMF (5.0 mL);

[0107] Reaction conditions and time: Reaction at 100℃ for 24 hours;

[0108] SEM cross-sectional image of the PET-P5A-MOF-1-AZO bullet-shaped nanochannel PET membrane, as shown. Figure 3 As shown.

[0109] III. The process parameters for PET-MOF-5 bullet-shaped nanochannels are as follows:

[0110] MOF-5 precursor solution: The tip side is a mixed solution of H2BDC (52 mg) and DMF (2.5 mL), and the base side is a mixed solution of Zn(NO3)2·6H2O (11.1 mg) and DMF (2.5 mL);

[0111] Reaction conditions and time: Reaction at 160℃ for 4 hours.

[0112] IV. The process parameters for PET-MOF-5-AZO bullet-shaped nanochannels are as follows:

[0113] MOF-5-AZO precursor solution: The tip side is a mixed solution of H2BDC (52 mg), AZO (3.87 mg) and DMF (5.0 mL), and the base side is a mixed solution of Zn(NO3)2·6H2O (11.1 mg), AZO (3.87 mg) and DMF (5.0 mL);

[0114] Reaction conditions and time: Reaction at 160℃ for 4 hours.

[0115] XRD patterns of P5A-MOF-1, P5A-MOF-1-AZO, PET-P5A-MOF-1, and PET-P5A-MOF-1-AZO, such as Figure 4 As shown in the figure, it can be seen that the P5A-MOF-1 crystal was successfully formed in the channel, and the introduction of AZO did not destroy the P5A-MOF-1 crystal structure.

[0116] FTIR of P5A-COOH, P5A-MOF-1, P5A-MOF-1-AZO and AZO, such as Figure 5 As shown in the figure, it can be seen that: at ~1580cm -1 The characteristic absorption peak of AZO appears at ~690 cm⁻¹. -1 and ~750cm -1 A monosubstituted aromatic CH out-of-plane bending vibration peak appears at this location.

[0117] Figure 4 and Figure 5 The results showed that AZO molecules were encapsulated within bullet-shaped nanochannels during the crystallization process of P5A-MOF-1.

[0118] XRD patterns of MOF-5, MOF-5-AZO, PET-MOF-5, and PET-MOF-5-AZO, such as Figure 6 As shown, this result indicates that MOF-5 crystals were successfully formed within bullet-shaped nanochannels, and the introduction of AZO did not disrupt the crystal structure of MOF-5.

[0119] Ion current was measured on PET film, PET-P5A-MOF-1-AZO and PET-P5A-MOF-1-AZO (bias voltage -2V), and the results are as follows. Figure 7 As shown; ion current tests were performed on PET-P5A-MOF-1-AZO and PET-MOF-5-AZO (bias voltage -2V), and the results are as follows. Figure 8 As shown;

[0120] from Figure 7 and Figure 8 It can be seen that the on / off ratio of P5A-MOF-1-AZO is significantly higher than that of MOF-5-AZO, which indicates that the PET-P5A-MOF-1-AZO nanochannel membrane has superior ion-gating performance.

[0121] The electrochemical switching performance of the PET-P5A-MOF-1-AZO nanochannel was tested under alternating UV irradiation (365 nm, 25 min) and solar recovery (2 h) conditions, and the results are as follows: Figure 9As shown in the figure, it can be seen that after multiple cycles, the current difference between the switching states remains significant and stable, indicating that the PET-P5A-MOF-1-AZO nanochannels possess excellent reversible electrochemical switching performance.

[0122] After four cycles of alternating UV (365nm) irradiation and sunlight (2h) irradiation, the XRD patterns of P5A-MOF-1-AZO nanochannels are as follows: Figure 10 As shown in the figure, it can be seen that the P5A-MOF-1 crystal structure remains intact after UV irradiation and solar radiation cycling.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing photoresponsive MOF-based ion-gated nanochannels based on columnar aromatic hydrocarbons, characterized in that, Includes the following steps: Bullet-shaped PET nanochannels were prepared using a combination of trajectory etching technology and surfactant-controlled etching. The process is as follows: One side of the PET film was placed in an etching solution composed of 6M NaOH aqueous solution and 0.025wt% sodium dodecyl diphenyl ether disulfonate, and the other side was placed in 6M NaOH aqueous solution. The etching temperature was set to 60℃. During the etching process, a transmembrane voltage of 1V was applied to monitor the ion current. When the current reached 65nA and the time was 200s, the etching solution was removed and a mixed stop solution composed of 1M potassium chloride and 1M formic acid was added to terminate the etching, resulting in bullet-shaped nanochannels distributed on the PET film. Bullet-shaped nanochannels modified with P5A-MOF-1-AZO were prepared using a reverse diffusion interface synthesis method, denoted as PET-P5A-MOF-1-AZO. The preparation process is described below: A PET membrane with bullet-shaped nanochannels was immersed in a polytetrafluoroethylene reaction chamber. The PET membrane divided the reaction chamber into two chambers. P5A-MOF-1-AZO precursor solution was added to each chamber and reacted. The chamber was then rinsed three times with ethanol and dried at room temperature overnight to obtain the modified bullet-shaped nanochannels. The process parameters for the PET-P5A-MOF-1-AZO bullet-shaped nanochannels are as follows: P5A-MOF-1-AZO precursor solution: P5A-COOH on the tip side. A mixed solution consisting of 20 mg Zn(NO3)2·6H2O, 3.87 mg AZO, and 5.0 mL DMF, with the base side being Zn(NO3)2·6H2O. Reaction conditions and time: Reaction at 100℃ for 24 hours; AZO stands for azobenzene.

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