Ion conduction type CO2 sensing material based on chiral hydrogen bond network and preparation method and device thereof

Abstract

The invention belongs to the technical field of gas sensing materials, and particularly relates to an ion conduction type CO2 sensing material based on a chiral hydrogen bond network and a preparation method and device thereof. The metal organic framework subject and the chiral small molecule object are compounded through interaction of the subject and the object, and the room-temperature CO2 sensing function is achieved. Wherein the metal organic framework main body has extremely strong CO2 adsorption capacity, and the chiral transfer phenomenon of the chiral small molecule object can promote the formation of an ordered and wide hydrogen bond network, so that the CO2 room temperature detection effect of the composite material is improved, and the composite material has the characteristics of low cost, high sensitivity, high stability and the like. Through dual mechanisms of adsorption capacity strengthening and chiral structure regulation, the high adsorption performance of the MOF subject and the ordered network construction capacity of the chiral object are combined, the bottleneck that a traditional CO2 sensing material is insufficient in sensitivity or high in cost at the room temperature is broken through, and the method has technical innovation and industrial application potential.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas sensing materials, and in particular relates to an ion-conducting CO2 sensing material based on a chiral hydrogen bond network, a preparation method thereof, and a device. Background Art

[0002] Specific gases in human exhaled breath are closely associated with certain diseases. For example, ammonia (NH3) in human exhaled breath is a marker for kidney disease, acetone (C3H6O) is a biomarker for blood sugar control in diabetes, hydrogen sulfide (H2S) is a specific marker for oral diseases, nitric oxide (NO) is a disease marker for asthma, and carbon dioxide (CO2) is a biomarker for chronic obstructive pulmonary disease (COPD). Unlike other components, human exhaled breath contains large amounts of CO2, and even slight changes in its concentration have extremely important clinical significance. In addition, metal-organic frameworks (MOFs) have attracted much attention in the field of sensing due to their unique porous structure, high specific surface area, and adjustable pores within the framework, which provide numerous possibilities for the loading and surface anchoring of functionalized objects.

[0003] Previous research by our research group has revealed that assembling ion-source guest molecules can enhance the ion conductivity of materials, resulting in excellent CO2 sensing capabilities. Building on this foundation, we proposed a novel concept: introducing chiral structures and leveraging chiral transfer to construct an ordered hydrogen-bonding network to enhance ion conductivity. Specifically, we selected chiral ion-source guest molecules and enabled them to interact with the cyclodextrin-MOF cavity, thereby fabricating an ion-conducting metal-organic framework (MOF) with an ordered hydrogen-bonding network, enabling room-temperature CO2 gas sensing. This invention is hereby proposed to provide a new technical solution for the field of CO2 gas sensing. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention proposes a method for preparing an ion-conducting metal-organic framework room-temperature CO2 gas sensor material in which an ordered hydrogen bond network is constructed by chiral molecules. The metal-organic framework host with strong CO2 adsorption ability is compounded with a chiral small molecule guest, and the chiral transfer characteristics of the chiral small molecules are utilized to promote the formation of an ordered and extensive hydrogen bond network in the system, thereby achieving efficient detection of CO2.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] The first aspect of the present invention provides an ion-conducting CO2 sensing material based on a chiral hydrogen bond network, wherein the sensing material comprises a metal-organic framework (MOF) host and a chiral guest molecule, wherein the chiral guest molecule is encapsulated into the metal-organic framework host through electrostatic interaction between the host and the guest;

[0007] The metal organic framework main body is one or more of α-cyclodextrin-MOF, β-cyclodextrin-MOF, and γ-cyclodextrin-MOF, and the chiral guest molecules include chiral guest molecules with different rigidity and flexibility, selected from one or more of tryptophan (Trp), lysine (Lys), serine (Ser), tyrosine (Tyr), and 2-aminoadipic acid (2-Amin); the chiral guest molecules are encapsulated inside the cyclodextrin-MOF by utilizing the chiral transfer phenomenon, thereby constructing an orderly and extensive hydrogen bond network.

[0008] Preferably, the chiral guest molecules include right-handed (D-type) or left-handed (L-type) chiral guest molecules of different rigidity and flexibility, selected from one or more of D-Trp, L-Trp, D-Lys, L-Lys, D-Ser, L-Ser, D-Tyr, L-Tyr, D-2-Amin, and L-2-Amin.

[0009] Preferably, the metal ion in the metal organic framework host is selected from one or more of potassium, magnesium, aluminum, copper, and zinc. More preferably, the metal ion in the metal organic framework host is potassium.

[0010] The second aspect of the present invention provides a method for preparing the ion-conducting CO2 sensing material based on the chiral hydrogen bond network described in the first aspect, specifically: dissolving the metal salt, cyclodextrin and chiral guest molecules in water, filtering, placing the resulting solution openly into a container containing a methanol solution, sealing it, and letting it stand for several days, then filtering and collecting the solid particles, and then washing, sonicating, filtering, and drying them to obtain the ion-conducting CO2 sensing material based on the chiral hydrogen bond network.

[0011] Preferably, the mass ratio of the metal-organic framework host to the chiral guest molecule is 1-50:1. More preferably, the mass ratio of the metal-organic framework host to the chiral guest molecule is 1-20:1. Furthermore, the mass ratio of the metal-organic framework host to the chiral guest molecule is 1-5:1.

[0012] Preferably, the cyclodextrin is at least one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0013] Preferably, the step of standing still for several days is 1 to 30 days. More preferably, the step of standing still for several days is 10 to 20 days.

[0014] Preferably, the washing, ultrasonication and filtration are repeated 3-5 times before drying. The washing is performed with methanol.

[0015] Preferably, the metal salt is selected from potassium hydroxide.

[0016] Preferably, the drying is vacuum drying, the drying temperature is 40-65° C., and the drying time is 12-24 hours.

[0017] Preferably, the cyclodextrin is 0.1-2.0 mmol, and the methanol solution is 10-100 mL. More preferably, the cyclodextrin is 0.2-1.0 mmol, and the methanol solution is 20-50 mL.

[0018] The third aspect of the present invention provides a CO2 sensor device, which is obtained by dispersing the ion-conducting CO2 sensor material based on the chiral hydrogen bond network described in the first aspect in an ethanol solution, and then coating the obtained dispersion on a gas-sensitive electrode.

[0019] Preferably, the gas-sensing electrode comprises a silver / palladium (Ag / Pd) interdigital electrode or a MEMS electrode. More preferably, the gas-sensing electrode is an interdigital electrode.

[0020] The fourth aspect of the present invention provides the use of the ion-conducting CO2 sensing material based on the chiral hydrogen bond network described in the first aspect, or the CO2 sensing device described in the third aspect in the detection of CO2 exhaled by the human body.

[0021] The present invention proposes a method for preparing an ion-conducting metal-organic framework room-temperature CO2 gas sensor material that constructs an ordered hydrogen bond network through chiral molecules. The method combines a metal-organic framework host with strong CO2 adsorption capacity with a chiral small molecule guest, and utilizes the chiral transfer phenomenon of the chiral guest to induce the formation of an ordered hydrogen bond network, thereby optimizing the ion conduction path and enhancing the molecular recognition ability. The prepared gas sensing material combines the advantages of high porosity adsorption with the function of hydrogen bond network regulation. It exhibits high sensitivity and high stability sensing performance for CO2 at room temperature, and the detection accuracy is close to that of commercial infrared detectors. In addition, the preparation process is simple, the raw material cost is low (using green edible cyclodextrin), and it is suitable for large-scale industrial production. The present invention provides a low-cost, high-performance sensing solution for non-invasive diagnosis of diseases such as chronic obstructive pulmonary disease (COPD), and has significant application potential in the field of medical testing.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention proposes a method for preparing an ion-conducting metal-organic framework room-temperature CO2 gas sensor material that constructs an ordered hydrogen bond network through chiral molecules. The chiral guest molecules are encapsulated into cyclodextrin-MOF by utilizing the chiral transfer phenomenon, thereby constructing a more ordered hydrogen bond network, giving it enhanced ion conduction ability and improving its CO2 sensing ability.

[0024] (2) The present invention proposes a method for preparing an ion-conducting metal-organic framework room-temperature CO2 gas sensor material in which an ordered hydrogen bond network is constructed by chiral molecules. In the prepared sensing material, the amino, carboxyl, hydroxyl, sulfonate and other groups on the chiral guest molecules are conducive to forming a stable hydrogen bond network with the metal-organic framework main body, which is conducive to ion conduction, thereby improving the gas sensing performance and chemical stability.

[0025] (3) The CO₂ sensing material proposed in the present invention, based on chiral molecules modulating the hydrogen bond network of a metal-organic framework, is used to detect CO₂ exhaled by the human body. It is cost-effective and highly stable, demonstrating potential for large-scale commercial applications. Therefore, the chiral molecule-modified metal-organic framework gas sensing material provided by the present invention can be applied to the detection of CO₂ in human exhaled breath.

[0026] (4) The human exhaled CO2 sensing material based on chiral molecule-regulated metal-organic framework ion conduction provided by the present invention has a simple preparation method, and the cyclodextrin used is a safe and edible green raw material, which is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The preparation and testing process of γ-CD-MOF@D-Trp based CO2 gas sensor;

[0028] Figure 2 The preparation flow chart of γ-CD-MOF@D-Trp gas sensing material;

[0029] Figure 3 The preparation flow chart of γ-CD-MOF@D-Trp based CO2 gas sensor;

[0030] Figure 4 Scanning electron microscope (SEM) images of γ-CD-MOF and γ-CD-MOF@D-Trp gas sensing materials;

[0031] Figure 5 This is the transmission electron microscopy (TEM) image of γ-CD-MOF@D-Trp gas sensing material;

[0032] Figure 6 Circular dichroism (CD) spectrum of γ-CD-MOF@D-Trp gas sensing material;

[0033] Figure 7 The resistance curve of the γ-CD-MOF@D-Trp based sensor to 1000 ppm CO2 at room temperature;

[0034] Figure 8The response curve of the γ-CD-MOF@D-Trp based sensor to 10-1000 ppm CO2 at room temperature;

[0035] Figure 9 Three cyclic response curves of γ-CD-MOF@D-Trp based sensor to 50, 800, and 1000 ppm CO2 at room temperature;

[0036] Figure 10 This is a comparison of the response values ​​of γ-CD-MOF and γ-CD-MOF@D-Trp based sensors to 1000 ppm CO2 at room temperature. DETAILED DESCRIPTION

[0037] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0038] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used in the following examples are commercially available unless otherwise specified.

[0039] The following examples illustrate a method for preparing an ion-conducting metal-organic framework room-temperature CO2 gas sensing material (γ-CD-MOF@D-Trp) by constructing an ordered hydrogen bond network through chiral molecules. Figure 1 As shown, KOH, γ-cyclodextrin, and D-tryptophan were first dissolved and ultrasonically filtered, then sealed with methanol solution, allowed to stand, washed, and dried to obtain CD-MOF@D-Trp solid particles; then they were dispersed in ethanol and ultrasonically coated with interdigital electrodes to make a sensor; finally, a digital source meter was connected, and gas sensing tests were carried out with a bias voltage at room temperature, and the sensing response performance was presented through the curve.

[0040] In order to comprehensively and clearly present the technical solutions and significant advantages of the present invention, the present invention is described in detail below in conjunction with specific embodiments.

[0041] Example 1:

[0042] This embodiment provides a method for synthesizing a hydrogen bond network-gained ion-conducting gas sensing material based on γ-CD-MOF@D-Trp. The specific steps are as follows:

[0043] (1) 2.3 mmol KOH, 0.22 mmol γ-cyclodextrin and 0.33 mmol D-tryptophan were fully dissolved in 5 mL water. After ultrasonic filtration (0.22 μm nylon filter membrane), the resulting solution was placed in a 25 mL glass bottle. The solution was then opened and placed in a glass bottle containing 20 mL methanol solution (analytical grade). The glass bottle was sealed and allowed to stand for 14 days. After filtration, the resulting solid particles were washed with methanol, ultrasonically dispersed, and filtered. This operation was repeated 3 times and then dried (60 ° C, 20 h). Finally, cyclodextrin-MOF solid particles encapsulating chiral guests (γ-CD-MOF@D-Trp) were obtained ( Figure 2 ).

[0044] The morphology of the prepared γ-CD-MOF@D-Trp was studied by SEM ( Figure 4 ) and TEM( Figure 5 ) characterization, the results showed that the prepared γ-CD-MOF@D-Trp has a cubic structure. Then the circular dichroism (CD) spectrum was analyzed ( Figure 6 ), indicating that γ-CD-MOF@D-Trp is chiral and right-handed as a whole, and there is a chiral transfer phenomenon, which also confirms the successful synthesis of the composite material.

[0045] (2) The obtained γ-CD-MOF@D-Trp solid particles were dispersed in anhydrous ethanol and ultrasonicated for 30 min (0.1 mg / mL), and then 10 μL was taken and coated on the Ag / Pd interdigital electrode (13.4×7 mm), thus obtaining the γ-CD-MOF@D-Trp-based CO2 gas sensor ( Figure 3 ).

[0046] (3) Application of γ-CD-MOF@D-Trp sensing material in gas sensitive monitoring:

[0047] The electrode sheet coated with γ-CD-MOF@D-Trp was connected to a digital source meter (Keithley 2450) with a bias voltage of 20 V, and the gas sensing test was performed at room temperature (25 ± 3 °C).

[0048] The results showed that the response value of the γ-CD-MOF@D-Trp based sensor to 1000ppm CO2 was 2.10 at room temperature, and the response (T res ) / Restore(T rec ) time is 161s / 513s( Figure 7 ), showing a good linear relationship for CO2 concentrations of 10-1000ppm ( Figure 8At the same time, the sensor's response curves to three CO2 gas concentrations of 50ppm, 800ppm and 1000ppm showed regular and stable changes in multiple cycle tests. At different concentrations, the response value (R g / R o ) with time (Time) and the recovery process are highly repeatable, indicating that the sensor has good cyclic stability for three concentrations of CO2 gas: 50ppm, 800ppm and 1000ppm ( Figure 9 ), providing performance support for reliable detection of different concentrations of CO2. It can be seen that the sensor prepared in this example has excellent and stable sensing performance for CO2, indicating that the introduction of chiral molecules improves the CO2 response performance of the composite material.

[0049] Comparative Example 1:

[0050] This example provides a synthesis method based on unmodified γ-CD-MOF, and the specific steps are as follows:

[0051] (1) A certain amount of KHCO3 and γ-cyclodextrin were fully dissolved in an appropriate amount of water. After ultrasonic filtration, the resulting solution was placed in a glass bottle of appropriate size. The open bottle was then placed in a glass bottle containing 20 mL of methanol solution. The glass bottle was sealed and allowed to stand for 14 days. After filtration, the resulting solid particles were washed with methanol, ultrasonicated, and filtered. This operation was repeated three times and then dried to finally obtain cyclodextrin-MOF solid particles (γ-CD-MOF).

[0052] (2) The obtained γ-CD-MOF solid particles were dispersed in an ethanol solution and ultrasonicated for 30 min, and then coated on an interdigital electrode to obtain a γ-CD-MOF-based CO2 gas sensor.

[0053] (3) Application of γ-CD-MOF sensing materials in gas sensitive monitoring:

[0054] The electrode sheet coated with γ-CD-MOF was connected to a gas detection workstation, a bias voltage of 20 V was provided, and gas sensing tests were performed at room temperature (25±3°C).

[0055] The test results show that ( Figure 10 ), the response value of the γ-CD-MOF sensing material to 1000 ppm of CO2 is 1.13, which is much lower than the response value in Example 1.

[0056] In summary, the present invention compounds the cyclodextrin-MOF host with the chiral guest molecule through host-guest interaction, utilizes the high porosity of the metal organic framework host itself to improve the adsorption capacity of CO2, and at the same time constructs an ordered hydrogen bond network structure with the help of the chiral transfer phenomenon of chiral molecules, thereby achieving effective regulation of ion conduction ability, and enhancing the chemical stability of the metal organic framework host through the functional groups on the chiral molecules, thereby improving its CO2 detection effect, making it have the characteristics of low cost, high sensitivity, and high stability.

[0057] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. An ion-conducting CO2 sensing material based on a chiral hydrogen bond network, characterized in that: The sensing material includes a metal organic framework main body and a chiral guest molecule, wherein the chiral guest molecule is encapsulated into the metal organic framework main body through electrostatic interaction between the host and the guest; The metal organic framework main body is one or more of α-cyclodextrin-MOF, β-cyclodextrin-MOF, and γ-cyclodextrin-MOF, and the chiral guest molecule includes chiral guest molecules with different rigidity and flexibility, selected from one or more of Trp, Lys, Ser, Tyr, and 2-Amin.

2. The ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to claim 1, characterized in that: The chiral guest molecules include right-handed or left-handed chiral guest molecules of different rigidity and flexibility, and are selected from one or more of D-Trp, L-Trp, D-Lys, L-Lys, D-Ser, L-Ser, D-Tyr, L-Tyr, D-2-Amin, and L-2-Amin.

3. The ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to claim 1, characterized in that: The metal ions in the metal organic framework are selected from one or more of potassium, magnesium, aluminum, copper and zinc.

4. The method for preparing the ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to any one of claims 1 to 3, characterized in that: The metal salt, cyclodextrin and chiral guest molecules are dissolved in water. After filtering, the resulting solution is opened and placed in a container containing methanol solution, sealed and left to stand for several days. The solid particles are then filtered and collected. After washing, ultrasonication, filtration and drying, an ion-conducting CO2 sensing material based on a chiral hydrogen bond network is obtained.

5. The method for preparing an ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to claim 4, characterized in that: The mass ratio of the metal organic framework host to the chiral guest molecule is 1-50:

1.

6. The method for preparing an ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to claim 4, characterized in that: The said standing for several days is 2-30 days.

7. The method for preparing an ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to claim 4, characterized in that: The washing, ultrasonication and filtration are repeated 3-5 times, and then drying is performed.

8. A CO2 sensor device, characterized in that: The ion-conducting CO2 sensing material based on the chiral hydrogen bond network according to any one of claims 1 to 3 is dispersed in an ethanol solution, and the obtained dispersion is then coated on a gas-sensitive electrode to obtain a CO2 sensor device.

9. A CO2 sensor device according to claim 8, characterized in that: The gas-sensitive electrode includes a silver / palladium interdigital electrode or a MEMS electrode.

10. Use of the ion-conducting CO2 sensing material based on a chiral hydrogen bond network according to any one of claims 1 to 3, or the CO2 sensing device according to claim 8 or 9 in detecting CO2 exhaled by a human body.

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