Single-molecule device for detecting small-molecule gas based on supramolecules and preparation method of single-molecule device

Abstract

The invention relates to the technical field of single-molecule devices, in particular to a single-molecule device for detecting small-molecule gas based on supramolecules and a preparation method of the single-molecule device. The monomolecular device comprises a functional molecule and a graphene electrode pair, wherein the functional molecule is connected between the graphene electrode pair through an amido bond. A cucurbituril hydrophobic cavity structure in the functional molecular structural formula can contain and capture target small molecular gas, gas molecules of different volumes are selectively included through multiple weak interaction, a dynamically-adjustable subject-object compound structure is formed, and then switching type sensing detection on the small molecular gas is achieved. The amino terminal of the end part of the main bridging unit in the functional molecule can be connected with the carboxyl terminal of the graphene point electrode in a covalent bond manner, and amide condensation molecular chain connection is formed at the two ends of the graphene point electrode, so that the stability of a monomolecular device is improved. The preparation method provided by the invention is simple in process, mild and controllable in reaction condition and beneficial to large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of single-molecule devices, and particularly to a single-molecule device for detecting small-molecule gas based on supramolecules and a preparation method thereof. BACKGROUND

[0002] The detection of small-molecule gases such as hydrogen, oxygen, nitrogen, methane, carbon monoxide and carbon dioxide is widely used in the fields of energy, environmental monitoring, catalytic reaction, gas separation and purification, etc. At present, small-molecule gas detection technology is developing in a diversified manner, but still faces many challenges. In traditional detection methods, electrochemical sensors have low cost but are easily affected by environmental humidity and temperature, resulting in fluctuations in detection accuracy. For example, the detection error of carbon dioxide in a high-humidity environment can exceed 15%. Optical sensing technology (such as infrared spectroscopy) has high selectivity, but has limitations such as large equipment size and difficulty in achieving portable detection. Gas chromatography can analyze multiple components of gas simultaneously, but has a long detection period and cannot meet the demand for real-time monitoring. With the upgrading of demand in the fields of energy security and environmental governance, higher requirements are put forward for the sensitivity, response speed and anti-interference ability of small-molecule gas detection, and traditional technology has been difficult to fully adapt.

[0003] A single-molecule device refers to a nanoscale device that takes a single molecule as a core functional unit and realizes a specific function through the electronic, optical, mechanical or chemical properties of the molecule. It is a frontier field of nanotechnology and molecular electronics. As an ultraminiature device with specific functions at the molecular level, a single-molecule device not only has important technical significance, but also plays a key role in scientific exploration and future industrial development. As a core research direction of molecular electronics, single-molecule devices have made some progress in preparation technology and functional exploration in recent years. Through mechanical controllable break junction technology, electromigration and other means, precise connection of a single molecule with an electrode can be achieved, and single-molecule devices with rectification, switching and other functions can be constructed. For example, a photo-controlled single-molecule switch based on diaryene molecules has a switching ratio of more than 10². In the field of gas detection, single-molecule devices have the advantage of single-molecule level size and can theoretically realize single-molecule recognition of gas molecules, with much higher sensitivity than traditional devices. However, there are still outstanding problems in this field: first, the device stability is poor, and the interface interaction between the molecule and the electrode is easily affected by environmental factors (such as temperature, humidity and gas atmosphere), resulting in a short device life and a short continuous working time of most devices; second, signal reading is difficult, and the electrical signal of a single-molecule device is weak (usually in the order of pA), which is easily disturbed by background noise and requires high-precision detection systems; third, it is difficult to mass-produce single-molecule devices, and existing technologies cannot achieve batch and uniform production of single-molecule devices, which restricts their practical application. SUMMARY

[0004] The present application aims to at least solve one of the problems in the related art. To this end, a first object of the present application is to provide a supramolecular-based single-molecule device for detecting small molecule gas, and a second object of the present application is to provide a preparation method of the supramolecular-based single-molecule device for detecting small molecule gas.

[0005] To achieve the first object, the technical solution adopted by the present application is as follows: The supramolecular-based single-molecule device for detecting small molecule gas comprises a pair of graphene electrodes and a functional molecule connected between the pair of graphene electrodes by an amide bond. The functional molecule has the following structure: n1 is any integer from 1 to 4. Among them, as a hydrophobic cavity unit for capturing small molecule gas; as a host bridging unit, the -NH2 at both ends of the host bridging unit is dehydrated and condensed with the -COOH on the pair of graphene electrodes to form an amide bond.

[0006] The single-molecule device of the functional molecule formed by the supramolecular structure has significant advantages over traditional single-molecule devices. Among them, the hydrophobic cavity unit has a cucurbituril cavity structure that can accommodate target small molecule gas such as CH4, CO, etc., selectively encapsulate gas molecules of different volumes through multiple weak interactions, form a dynamic adjustable host-guest complex structure, cause changes in molecular bridge configuration or charge distribution on the single-molecule device before and after, significantly change the conductance signal, and realize a "switching type" sensor for detecting small molecule gas. At the same time, the supramolecular structure with cucurbituril structure is sensitive to temperature, which can be used for small molecule gas adsorption-desorption, which is reflected in the conductance signal, and thus realizes the capture and detection of small molecule gas with good reproducibility. The host bridging unit has a carbazole derivative structure, and the amino terminal at the end thereof can be connected to the carboxyl terminal of the graphene point electrode by a covalent bond, forming an amide condensation molecular chain between the graphene point electrodes, thereby improving the stability of the single-molecule device.

[0007] Preferably, a single functional molecule is connected between the pair of graphene electrodes.

[0008] Preferably, the graphene electrode is an array electrode.

[0009] Preferably, the graphene electrode is a nano-gap electrode.

[0010] To achieve the second object, the technical solution adopted by the present application is as follows: The preparation method of the single-molecule device for detecting small molecule gas based on supramolecule, for preparing the single-molecule device for detecting small molecule gas based on supramolecule, comprises the step of connecting the functional molecule and the graphene electrode pair through an amide bond, and the process is as follows: S100, acylating the graphene electrode pair through a condensation reaction to obtain an acyl-containing graphene electrode pair; S200, placing the acyl-containing graphene electrode pair in an organic solution of the functional molecule compound with a concentration not less than 1 mM, and reacting for 0.5-1 h, so that the functional molecule is connected to the graphene electrode pair through an amide bond to form a molecular link, thereby obtaining the single-molecule device for detecting small molecule gas based on supramolecule.

[0011] Preferably, in step S100, the condensing agent used in the condensation reaction is selected from oxalyl chloride.

[0012] Preferably, in step S100, the catalyst used in the condensation reaction is selected from anhydrous aluminum chloride, and the reaction solvent is selected from dichloromethane.

[0013] Preferably, in step S200, the solvent used for preparing the organic solution of the functional molecule compound is tetrachloroethane.

[0014] Preferably, the preparation method of the functional molecule is as follows: S210, preparing the compound I containing a hydrophobic cavity unit by using cucurbituril . n is selected from any integer between 5 and 8; S220, preparing the intermediate by using as raw materials; ; S230, preparing the compound II by using the intermediate through an azidation reaction; S240, obtaining the functional molecule by reacting the compound I and the compound II to form a supramolecular structure .

[0015] Preferably, in the preparation step S230, the azidation reagent used in the azidation reaction is selected from .

[0016] The one or more technical solutions in the embodiments of the present application have at least one of the following technical effects: The present application provides a single-molecule device for detecting small molecule gas based on supramolecule and a preparation method thereof. The single-molecule device comprises a functional molecule and a graphene electrode pair, the functional molecule is connected between the graphene electrode pair through an amide bond, and the structural formula of the functional molecule is The cucurbituril hydrophobic cavity structure in the structural formula can accommodate and capture target small molecule gas (such as CH4, CO and the like), and through multiple weak interactions, different volumes of gas molecules are selectively encapsulated to form a dynamically adjustable host-guest complex structure. Before and after the gas molecules are combined with the functional molecules, the configuration or charge distribution of the molecular bridge on the single-molecule device will change, thereby significantly changing the conductance signal, and realizing the "on-off type" sensing and detection of the small molecule gas. At the same time, by using the sensitivity of the supramolecule with the cucurbituril structure to temperature, the adsorption and desorption of the small molecule gas can be realized, and the adsorption and desorption process can be reflected by the conductance signal, thereby realizing the capture and detection of the small molecule gas, and the reproducibility is good. The host bridging unit has a carbazole derivative structure, and the amino terminal at the end thereof can be connected with the carboxyl terminal of the graphene dot electrode by a covalent bond, so that the molecular chain connected by amide condensation is formed at both ends of the graphene dot electrode, and the stability of the single-molecule device is improved.

[0017] The preparation method of the single-molecule device for detecting small molecule gas based on supramolecule provided by the application has simple process, mild and controllable reaction conditions, and is beneficial to large-scale production.

[0018] Additional aspects and advantages of the application will be described in part below, some will become apparent from the following description, or will be understood by those skilled in the art through practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of the single-molecule device for detecting small molecule gas based on supramolecule provided by the embodiment of the application.

[0020] Figure 2 is a I-t curve test result graph of the graphene device without connecting functional molecules provided by the embodiment of the application.

[0021] Figure 3 is a I-t curve test result graph of the single-molecule device for detecting small molecule gas based on supramolecule provided by the embodiment of the application.

[0022] Figure 4 is a I-t curve test result graph of the single-molecule device for detecting small molecule gas based on supramolecule under H2 gas atmosphere provided by the embodiment of the application.

[0023] Figure 5 is a I-t curve test result graph of the single-molecule device for detecting small molecule gas based on supramolecule under CH4 gas atmosphere provided by the embodiment of the application.

[0024] REFERENCE NUMERALS 1, functional molecule; 2, graphene electrode pair. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in connection with specific embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application. The following embodiments are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0026] In the following examples, the experimental methods used are conventional methods, and the materials, reagents and the like used are obtained from commercial channels, unless otherwise specified, according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0027] As shown in Figure 1 , the supramolecular-based single-molecule device for detecting small-molecule gas includes a functional molecule 1 and a pair of graphene electrodes 2, and the functional molecule 1 is connected between the pair of graphene electrodes 2 through an amide bond. The structural formula of the functional molecule is as follows: n1 is any integer from 1 to 4; As a hydrophobic cavity unit, it is used for capturing small-molecule gas. As a host bridging unit, the -NH2 at both ends of the host bridging unit is dehydrated and condensed with the -COOH on the pair of graphene electrodes to form an amide bond connection. In the following examples, the preparation process of the functional molecule and the supramolecular-based single-molecule device for detecting small-molecule gas is described by taking n1 as 1 as an example.

[0028] Example 1

[0029] Preparation of functional molecule The process is as follows: I. Preparation of hydroxylated calix[5]urea .

[0030] Calix[5]urea (1 g, 1.204 mmol) was dissolved in a 12M aqueous HCl solution (125 mL), and under the condition of nitrogen, 30wt% hydrogen peroxide in H2O solution (65 μL, containing hydrogen peroxide 0.62 mmol) was added, and under the irradiation of ultraviolet light (254 nm), after stirring the reaction for 48 h, an aliquot of the reaction mixture was taken, and the reaction was terminated by adding 1 mL of 30wt% hydrogen peroxide in H2O solution. 1 ​The reaction was monitored by H NMR. After the reaction was completed, the solvent was evaporated under reduced pressure to obtain a white solid. The white solid was dissolved in 950 μL of a mixed solvent of H2O and HCOOH (the volume ratio of H2O to HCOOH was 1:1) and loaded onto silica gel 60 (particle size 0.04-0.063 mm). The mixture was eluted with a mixed solvent of H2O / AcOH / HCOOH (the volume ratio of H2O, AcOH and HCOOH was 10:10:1.5). The eluate was collected in sections (the number of collected fractions was not less than 250, each 2 ml) to obtain the hydroxylated cucurbit[5]uril.

[0031] 2. Preparation of Compound Ⅰ .

[0032] The hydroxylated cucurbit[5]uril (20 mg, 23 µmol) prepared by the above method was dissolved in anhydrous dimethylsulfoxide (DMSO) (1.5 mL), and then solid NaH (0.4 mmol) was added. After stirring at 25 °C for 3 h, the mixture was cooled to 0 °C, and propargyl bromide (4.4 mmol) was added. After stirring at 25 °C for 12 h, ether (50 mL) was added to obtain a precipitate. The precipitate was washed three times with MeOH (25 mL) and dried under high vacuum (pressure ≤ 0.1 kPa) to obtain compound I.

[0033] 3. Preparation .

[0034] Under nitrogen atmosphere and 0℃, (3.89 g) was dissolved in H2SO4 (120 mL), and then N-bromosuccinimide (8.0 g, 45 mmol) was added. After stirring for 10 h, deionized water (40 mL) was added to quench the reaction, and the reaction solution was extracted with dichloromethane (3×20 mL). The organic layer was collected and dried over acid anhydride Na2SO4, and then purified by silica gel column chromatography. The elution solvent was a mixed solvent of petroleum ether / dichloromethane (the volume ratio of petroleum ether to dichloromethane was 1:2) to obtain , with a yield of 87%.

[0035] Under argon atmosphere, the (0.335mmol), (0.67mmol), CuI (0.03mmol), L-proline (0.03mmol) and K2CO3 (139mg, 1mmol) were dissolved in DMSO and reacted at 120℃ for 24h. After that, deionized water (40ml) was added to quench the reaction. The reaction solution was extracted with ethyl acetate (3×20mL), and the organic layer was collected and dried over acid anhydride Na2SO4. The organic layer was filtered and the solvent was evaporated in vacuo. Then, the product was purified by silica gel column chromatography with a mixed solvent of n-hexane / ethyl acetate (the volume ratio of n-hexane to ethyl acetate was 3:1) as the eluting solvent to obtain , with a yield of 90%.

[0036] 4. Preparation .

[0037] Will (6.15mmol, 2g) and SnCl2•2H2O (43.07mmol, 9.2g) were added to ethanol (60mL), stirred evenly, and refluxed at 25℃ for 16h. After quenching with ice water, the reaction solution was adjusted to pH 9 with a 0.1 mol / L NaHCO3 aqueous solution, and extracted with dichloromethane (3×30mL). The organic layer was collected, dried over MgSO4 anhydride, concentrated under reduced pressure, and the residue was recrystallized from toluene to obtain , with a yield of 70%.

[0038] 5. Preparation of intermediates .

[0039] Prepared according to the above method (0.5mmol), (0.5 mmol), bipyridine (7.8 mg, 0.05 mmol) and manganese powder (27 mg, 0.5 mmol) were added sequentially to a dried screw-capped test tube with a stirring bar, and the test tube was transferred to a glove box. Nickel(II) dichloride (ethylene glycol dimethyl ether) (NiCl2-DME) (0.025 mmol, 5.5 mg) and potassium tert-butoxide (0.55 mmol, 62 mg) were then added to the test tube using a syringe. Dimethylformamide (DMF) (1.5 mL) was then added, and the test tube was sealed. After stirring at 60 °C for 20 h, concentrated hydrochloric acid and deionized water (40 ml, a volume ratio of 1:1) were poured into the reaction to quench the reaction. The reaction solution was extracted with ethyl acetate, and the organic layer was collected. The collected organic layer was washed with saturated sodium chloride, dried over Na2SO4, and purified by silica gel column chromatography with a mixed solvent of n-hexane and ethyl acetate (a volume ratio of n-hexane to ethyl acetate of 9:1) as the eluting solvent to obtain , with a yield of 98%.

[0040] The obtained (0.5mmol), (0.5mmol), bipyridine (7.8mg, 0.05mmol) and manganese powder (27mg, 0.5mmol) were added in sequence to a dried screw-cap test tube with a stirring bar, and then the test tube was transferred to a glove box. NiCl2-DME (0.025mmol, 5.5mg) and potassium tert-butoxide (0.55mmol, 62mg) were added to the test tube with a syringe, and then DMF (1.5mL) was added. The test tube was sealed and stirred at 60°C for 20h. Concentrated hydrochloric acid and deionized water (40ml, the volume ratio of the two was 1:1) were added to quench the reaction, and the reaction solution was extracted with ethyl acetate. The organic layer was collected, and the collected organic layer was washed with saturated sodium chloride, dried over Na2SO4, and purified by silica gel column chromatography. The elution solvent was a mixed solvent of n-hexane and ethyl acetate (the volume ratio of n-hexane to ethyl acetate was 9:1). , with a yield of 73%.

[0041] VI. Preparation of Compound II .

[0042] The obtained (0.5mmol), (0.5mmol), triphenylphosphine (13mg, 0.5mmol) were added sequentially into a dried screw-capped test tube with a stirring bar, and the test tube was then transferred to a glove box. Subsequently, diethyl azodicarboxylate (3ml) and anhydrous THF (15mL) were added into the test tube with a syringe, and the test tube was sealed. After stirring at 25°C for 2h, the reaction was concentrated under reduced pressure and purified by silica gel column chromatography. The elution solvent was a mixed solvent of n-hexane and ethyl acetate (the volume ratio of n-hexane to ethyl acetate was 9:1), and the product was obtained. .

[0043] 7. Synthesis of functional molecules .

[0044] Under nitrogen atmosphere, the (0.5mmol) and (0.5mmol) was dissolved in an aqueous solution with a mass concentration of 55% DMSO, and then tri[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA) (0.5mmol), CuSO4·5H2O (8mg, 0.05mmol) and sodium ascorbate (NaAsc) (39.62mg, 0.2mmol) were added in sequence. After stirring at 25℃ for 10h, deionized water (40mL) was added to quench the reaction, and the reaction solution was extracted with dichloromethane (3×20mL). The organic layer was collected and dried over Na2SO4. After purification by silica gel column chromatography, the elution solvent was a mixed solvent of n-hexane and ethyl acetate (the volume ratio of n-hexane to ethyl acetate was 3:1) to obtain the functional molecule. ,That 1 The H NMR characterization results are as follows: 1 H NMR (500 MHz, chloroform- d ): δ 8.06(d, J =7.7Hz, 2H), 7.74–7.69(m, 4H), 7.63(d, J =1.9Hz, 2H), 7.63–7.60(m, 4H), 7.56(dd, J =7.7, 2.1Hz, 2H), 7.54–7.50(m, 4H), 6.71–6.66(m, 4H), 5.42(d, J =1.7Hz, 5H), 5.40(d, J =3.7Hz, 1H), 5.37(dd, J =4.6, 3.7Hz, 2H), 5.18(s, 2H), 5.13(s, 2H), 5.07(s, 4H), 5.07(s, 4H), 5.06(d, J =1.1Hz, 3H), 5.03(s, 6H), 4.42(t, J =6.3Hz, 2H), 4.21(d, J =5.7Hz, 2H), 4.13(d, J =5.7Hz, 2H), 2.89(t, J =7.7Hz, 2H), 2.22–2.11(m, 2H).

[0045] Example 2 The process of preparing a single-molecule device based on supramolecular detection of small molecule gases is as follows: 1. Prepare a device with a graphene electrode pair.

[0046] Cut the copper sheet into regular shape with scissors, and wear gloves all the time to avoid direct contact with the copper sheet; immerse the copper sheet into ultrapure water and treat it with ultrasonic for 15 min, then take it out and rinse it with ethanol to obtain clean copper sheet.

[0047] Put the clean copper sheet into a chemical vapor deposition (CVD) furnace, grow graphene film on the copper sheet by growing at 1030℃ for 100 min under the atmosphere of hydrogen and methane, and then take it out after cooling to obtain the graphene film grown on the copper sheet.

[0048] Fix the copper sheet with graphene film on a clean glass slide with transparent tape, spin coat polymethyl methacrylate (950 PMMA) polymer on the copper sheet at a speed of 4000 rpm for 40 s on a spin coater, and then bake it at 180℃ for 2 min on a hot table; after cooling, take off the transparent tape, and turn the copper sheet upside down to etch the back surface with oxygen plasma for 45 s. Take three clean 200 mL petri dishes, respectively marked as ①, ② and ③, and each of them is filled with 150 mL of ultrapure water, and 10 mL of concentrated hydrochloric acid is added to ① and mixed evenly; cut the treated copper sheet into small pieces, and put them into concentrated ferric chloride solution for etching for 4 h, and then take out the graphene film floating on the surface of the ferric chloride solution with a 1×1 cm 2 , and the thickness of the silicon sheet is 675±25 μm; take out the graphene film from ① and place it in ② for 15 min; transfer the graphene film in ① to ② one by one, and process it in the same way.

[0049] Fix the graphene film in ③ on a 1×1 cm 2 , and the thickness of the silicon sheet is 675±25 μm, and place it in a cool and dry place overnight.

[0050] Put the above dried sample into a crystallization dish, add acetone to cover the sample, heat it at 80℃ for 8 min on a hot table to remove PMMA, and then place the sample in ethanol and dry it with a nitrogen gun to obtain a single-layer graphene film.

[0051] Spin coat and photoetch the single-layer graphene film: spin coat the resist on the graphene film at a speed of 4000 rpm for 40 s on a spin coater, and then heat it at 110℃ for 3 min on a hot table; photoetch mark, and set the exposure time to 4 s; after photoetching all the samples, develop them with 1:7 diluted developer (developer is a mixture of methyl isobutyl ketone and ultrapure water in a volume ratio), and obtain the mark.

[0052] After the graphene sample after the label development, the magnetron sputtering film processing is carried out: under the condition of vacuum degree 0.0006 Pa, pre-sputtering chromium (50 W, 30 s), and then formal sputtering chromium (50 W, 100 s); then pre-sputtering gold (50 W, 30 s), and then formal sputtering gold (50 W, 100 s).

[0053] After the film processing, the sample is immersed in acetone and ultrasonically treated for 5 min to remove the gold foil except the label, and a gold-labeled graphene electrode pair array is obtained.

[0054] Photolithography strip processing is carried out: spin coating photoresist on a spin coater at a speed of 4000 rpm for 40 s, and heating at 110°C on a hot table for 3 min after spin coating; the exposure time is set to 4 s during the photolithography strip, and after all the samples are processed by photolithography, the developer diluted at a volume ratio of 1:7 (the developer is mixed by methyl isobutyl ketone and ultrapure water at a volume ratio) is used for development processing, and a strip is obtained; the sample after development is placed in the oxygen plasma etching (Reactive Ion Etching, RIE) for 45 s, and only the part protected by the strip is not etched away.

[0055] The surface of the sample after oxygen plasma etching is washed with acetone, and photolithography electrode processing is carried out: spin coating photoresist on a spin coater at a speed of 4000 rpm for 40 s, and heating at 110°C on a hot table for 3 min after spin coating; the exposure time is set to 4 s during the photolithography electrode, and after all the samples are processed by photolithography, the developer diluted at a volume ratio of 1:7 (the developer is mixed by methyl isobutyl ketone and ultrapure water at a volume ratio) is used for development processing, and a graphene electrode pair array is obtained.

[0056] The graphene electrode pair array is placed on a spin coater and spin coated with PMMA at a speed of 4000 rpm for 40 s, and heated at 180°C on a hot table for 2 min after spin coating, and electron beam exposure processing is carried out; after the processing, the developer diluted at a volume ratio of 1:3 (the developer is mixed with isopropyl alcohol at a volume ratio of 1:3) is used for development for about 18 s, and after fixing with isopropyl alcohol, clear graphene nanostrip gaps are observed under a 100x microscope.

[0057] Take anhydrous aluminum chloride (0.2 g) in a 100 mL two-necked flask, dissolve with tetrachloroethane (40 mL), stir at 500 rpm for 10 h under the condition of 25℃ in anhydrous environment, then inject oxalyl chloride (0.4 mL) into the reaction system; place the treated device in the two-necked flask, connect the condenser tube, and react at 99℃ for 12 h to obtain an array of graphene electrode pairs with terminal amide. Gently take the graphene device out of the two-necked flask, rinse it with dichloromethane, then immerse it in ice acetic acid-containing ultrapure water for 15 min, and blow it dry with a nitrogen gun to obtain a device containing acyl graphene electrode pairs. Test the current of the device at 25℃, and the I-t curve test results are shown in Figure 2 .

[0058] Immerse the device containing acyl graphene electrode pairs in a 1 mM functional molecule dichloromethane solution for 1 h, then take it out with tweezers, rinse it with ultrapure water, repeat the rinsing three times, and blow it dry with a nitrogen gun to obtain a supramolecule-based single-molecule device for detecting small molecule gas. Test the current of the device at 25℃, and the I-t curve test results are shown in Figure 3 .

[0059] Immerse the supramolecule-based single-molecule device for detecting small molecule gas in ultrapure water containing H2 or CH4 for 15 min, take it out with tweezers, and blow it dry with a nitrogen gun. Test the I-t curve of the single-molecule device at 25℃, and the results are shown in Figure 4 and Figure 5 .

[0060] The performance test process of the above device is as follows: place the supramolecule-based single-molecule device for detecting small molecule gas under the probe station at 25℃, and the probe station is connected to a source table; fix the bias at 0.5 V, test the change of current with time, and obtain the I-t curve.

[0061] Heat the supramolecule-based single-molecule device for detecting small molecule gas on the heating table at 50℃ for 3 min, then test the I-t curve under a bias of 0.5 V. The results show that heating can release gas molecules from the supramolecule-based single-molecule device for detecting small molecule gas, thereby indirectly proving that the supramolecular structure can realize the inclusion, detection and release of small molecule gas.

[0062] Test the change of current with time of the supramolecule-based single-molecule device for detecting small molecule gas at 25℃, and the results show that the I-t test results have good reproducibility, proving that the prepared graphene-based single-molecule-gas small molecule detector has good performance.

[0063] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A single-molecule device for detecting small molecule gases based on supramolecular molecules, characterized in that: It comprises a functional molecule and a graphene electrode pair, wherein the functional molecule is connected between the graphene electrode pair via an amide bond; The structural formula of the functional molecule is shown below: , n1 is selected from any integer from 1 to 4; in, As a hydrophobic cavity unit, it is used to capture small molecule gases; As a main bridging unit, -NH2 at both ends of the main bridging unit are respectively dehydrated and condensed with -COOH on the graphene electrode pair to form an amide bond connection.

2. The single-molecule device for detecting small molecule gases based on supramolecules according to claim 1, characterized in that: A single functional molecule is connected between the graphene electrode pairs.

3. The single-molecule device for detecting small molecule gases based on supramolecules according to claim 1, characterized in that: The graphene electrode is an array electrode.

4. The single-molecule device for detecting small molecule gases based on supramolecules according to claim 1, characterized in that: The graphene electrode is a nanogap electrode.

5. A method for preparing a single-molecule device for detecting small molecule gases based on supramolecular devices, characterized in that: The method for preparing a single-molecule device for detecting small molecule gases based on supramolecules according to any one of claims 1 to 4 comprises the steps of connecting a functional molecule to a graphene electrode pair via an amide bond, the process being as follows: S100, acylating the graphene electrode pair by a condensation reaction to obtain a graphene electrode pair containing an acyl group; S200, placing the graphene electrode pair containing acyl groups in an organic solution of a functional molecule compound having a concentration of not less than 1 mM, reacting for 0.5 to 1 hour, wherein the functional molecule and the graphene electrode pair are connected through an amide bond to form a molecular link, thereby obtaining a single-molecule device for detecting small molecule gases based on supramolecules.

6. The method for preparing a single-molecule device for detecting small molecule gases based on supramolecules according to claim 5, characterized in that: In step S100, the condensing agent used in the condensation reaction is selected from oxalyl chloride.

7. The method for preparing a single-molecule device for detecting small molecule gases based on supramolecules according to claim 5, characterized in that: In step S100, the catalyst used in the condensation reaction is selected from anhydrous aluminum chloride, and the reaction solvent is selected from dichloromethane.

8. The method for preparing a single-molecule device for detecting small molecule gases based on supramolecules according to claim 5, characterized in that: In step S200, the solvent used to prepare the organic solution of the functional molecular compound is tetrachloroethane.

9. The method for preparing a single-molecule device for detecting small molecule gases based on supramolecules according to claim 5, characterized in that: The preparation method of the functional molecule is as follows: S210, using cucurbituril , preparation of compound Ⅰ containing a hydrophobic cavity unit , n is selected from any integer between 5 and 8; S220, and As raw materials, prepare intermediates ; S230, using the azidation reaction of the intermediate to prepare compound II ; S240, using compound I and compound II to react to generate a supramolecular structure, to obtain a functional molecule .

10. The method for preparing a single-molecule device for detecting small molecule gases based on supramolecules according to claim 9, wherein: In the preparation step S230, the azidation reagent used in the azidation reaction is selected from .

Images