Synthesis method of hybrid organic-inorganic metal halide piezoelectric material and crystal based on chiral regulation

Abstract

The application relates to a synthesis method of a chiral-regulation-based hybrid organic-inorganic metal halide piezoelectric material and a crystal. A pair of chiral organic amines and CoCl2.6H2O are respectively dissolved in acetonitrile in a 2:1 substance amount ratio, and are stirred by ultrasonic stirring for 20 min; after the solution is completely clarified, volatilization is carried out at room temperature; block crystals are obtained after several days; and the chiral hybrid organic-inorganic hybrid metal halide crystals are obtained after being fished out S, S -(PHA)2CoCl4 and R, R -(PHA)2CoCl4. The chiral-synthesized hybrid organic-inorganic metal halide crystal has a stable structure. The synthesized hybrid organic-inorganic crystal has piezoelectric properties, the preparation method is simple and efficient, the product has high thermal stability and small environmental pollution, and the application lays a foundation for the development and application of a new type of hybrid organic-inorganic material in the sensing field.

Description

Technical Field

[0001] This invention belongs to the field of functional hybrid materials technology, and relates to a method for synthesizing a class of chiral-controlled hybrid organic-inorganic metal halide piezoelectric materials and crystals. Background Technology

[0002] The piezoelectric effect is a characteristic of asymmetric center (excluding the 432-point group) crystalline materials. It refers to the phenomenon where an external force applied to the crystal surface generates an electric charge, and the crystal returns to its uncharged state when the force is removed. When an alternating electric field is applied to a piezoelectric crystal, mechanical stress or deformation is generated in a certain direction. This stress or deformation disappears when the applied electric field is removed; this conversion of electrical energy into mechanical energy is called the inverse piezoelectric effect. Piezoelectric materials are widely used in piezoelectric sensing, energy harvesting, and filtering transducers. Most importantly, piezoelectric materials exhibit both direct and inverse piezoelectric effects. The inverse piezoelectric effect is central to many electronic technologies and has potential applications in television circuits, mobile phone RF front-end modules, and computer motherboards.

[0003] Piezoelectric materials are mainly classified into three categories: inorganic materials, polymeric materials, and hybrid organic-inorganic materials. Inorganic piezoelectric materials primarily include perovskite oxides such as quartz, lithium tantalate, barium titanate, and lead zirconate titanate. They possess superior and stable piezoelectric properties and high dielectric constants, making them widely used in filters, ultrasonic transducers, and piezoelectric sensors. Polymer piezoelectric materials mainly include polyvinylidene chloride (PVDF) and its copolymers. These piezoelectric materials offer advantages such as easy processing, low density, low acoustic impedance, and relatively high piezoelectric voltage constants, leading to their widespread application in underwater acoustic transducers, ultrasonic transducers, and pressure sensors. Hybrid organic-inorganic piezoelectric materials mainly include hybrid organic-inorganic perovskites and metal-organic frameworks, offering advantages such as simple synthesis, light weight, low acoustic impedance, and good biocompatibility. Some hybrid organic-inorganic piezoelectric materials exhibit piezoelectric properties comparable to piezoelectric ceramics, thus showing great application potential in nano-energy conversion and flexible wearable devices.

[0004] Hybrid organic-inorganic piezoelectric materials have attracted widespread attention due to their enormous application potential in fields such as electromechanical conversion, acoustic wave detection, and acoustic sensing. In 2019, researchers Xiong et al. discovered molecular solid solutions (TMFM). x (TMCM) 1-x -CdCl3 has a large d 33 The value is 1540 pC / N. Furthermore, researchers also discovered that the two-dimensional perovskite material (ATHP)₂PbBr₄ has a large g⁻¹. 33 The value is 660.3 × 10 -3These values, Vm / N, are far higher than those of existing commercial piezoelectric materials, such as PZT-5H(d 33 =593pC / N) and PVDF(g 33 =286.7×10 -3 (Vm / N). Currently, the piezoelectric properties of hybrid organic-inorganic piezoelectric materials-polymer composite films have great potential for development in the field of flexible batteries, and this property is often accompanied by other important properties, such as excellent mechanical properties, good stability, strong plasticity and high elasticity.

[0005] Therefore, how to select organic amine ligands as raw materials to synthesize a novel non-centrosymmetric hybrid organic-inorganic piezoelectric material and expand its application in the piezoelectric field is one of the major challenges facing the field of new functional materials. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned problems in existing technologies and to provide two chiral hybrid organic-inorganic metal halide piezoelectric materials and their synthesis methods. This invention utilizes chiral organic amine ligands as raw materials to synthesize crystals with piezoelectric signals. The reaction does not require high temperature and high pressure, has low requirements for experimental equipment, and crystals can grow at room temperature after solvent evaporation. It is a green, environmentally friendly, and simple preparation method.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention provides two hybrid organic-inorganic metal halide piezoelectric materials with different chiralities. The hybrid organic-inorganic metal halide piezoelectric materials are two hybrid organic-inorganic metal halide crystals with piezoelectric signals synthesized using chiral organic amine ligands as raw materials. Crystal I is named S,S-bis(α-methylbenzyl)cobalt tetrachloride with the chemical formula S,S-(PHA)2CoCl4, and crystal II is named R,R-bis(α-methylbenzyl)cobalt tetrachloride with the chemical formula R,R-(PHA)2CoCl4.

[0009] Furthermore, the two examples of hybrid organic-inorganic metal halide piezoelectric materials are non-centrosymmetric, zero-dimensional bulk crystals with space group P21.

[0010] The unit cell parameters of crystal I (P21) are: a=7.71150(10) Å b=22.0916(2) Å c=9.95360(10) Å, α=90°, β=105.3700(10)°, γ=90°.

[0011] The unit cell parameters of crystal II (P21) are: a = 7.70700(10) Å, b = 22.1249(2) Å, c = 9.94500(10) Å, α = 90o , β=105.3540(2)°, γ= 90 o .

[0012] Furthermore, the structural formula of the organic amine ligand is as follows:

[0013] and

[0014] (S,S) (R,R)

[0015] Furthermore, the two chiral hybrid organic-inorganic metal halide piezoelectric materials are blue bulk crystals and both possess piezoelectric properties.

[0016] Furthermore, the two chiral hybrid organic-inorganic metal halide piezoelectric materials exhibit excellent thermal stability, with decomposition temperatures of 244℃ (S,S) and 231℃ (R,R), respectively.

[0017] Furthermore, the hybrid organic-inorganic metal halide piezoelectric material exhibits a strong piezoelectric signal under the action of the clicker.

[0018] Furthermore, the chiral-controlled hybrid organic-inorganic metal halide crystal, after being electrospun into nanofiber cloth by electrospinning with polyvinylidene fluoride-trifluoroethylene copolymer (P(VDF-TrFE)) and fabricated into a device using a sandwich structure, exhibits a certain degree of improvement in piezoelectric performance compared to pure PVDF-TrFE devices.

[0019] This invention also provides two methods for synthesizing hybrid organic-inorganic metal halide crystals based on chiral regulation. Acetonitrile is used as a benign solvent, and S,S-bis(α-methylbenzyl)amine hydrochloride and R,R-bis(α-methylbenzyl)amine hydrochloride are used as raw materials. The crystals are prepared by a room-temperature solvent evaporation method, and the specific steps are as follows:

[0020] Step 1: Slowly dissolve cobalt chloride hexahydrate (CoCl2·6H2O) in acetonitrile, and sonicate at room temperature to dissolve the cobalt chloride hexahydrate, to obtain solution A;

[0021] Step 2: Add the organic amine ligands S,S-bis(α-methylbenzyl)amine hydrochloride and R,R-bis(α-methylbenzyl)amine hydrochloride to two bottles of solution A respectively, add acetonitrile solution to each bottle and sonicate at room temperature to obtain blue transparent clear solutions B and C; wherein the molar ratio of cobalt chloride hexahydrate to S,S-bis(α-methylbenzyl)amine hydrochloride and R,R-bis(α-methylbenzyl)amine hydrochloride is 1:2.

[0022] Step 3: Place the clear solutions B and C at room temperature and let them stand for 2-3 days to obtain two kinds of blue blocky crystals.

[0023] Step 4: After filtering the two types of block crystals from Step 3, place them in an oven and dry them to obtain two types of hybrid organic-inorganic metal halide crystals.

[0024] Furthermore, the molar ratio of cobalt chloride hexahydrate and S,S-bis(α-methylbenzyl)amine hydrochloride used is 1:2; the molar ratio of cobalt chloride hexahydrate and R,R-bis(α-methylbenzyl)amine hydrochloride is 1:2.

[0025] This invention also provides the application of the hybrid organic-inorganic metal halide piezoelectric material in the field of sensors, and studies the process of mutual conversion between mechanical energy and electrical energy of matter.

[0026] The present invention discloses the following technical effects:

[0027] This invention utilizes chiral organic amine ligands as raw materials to prepare novel chiral non-centrosymmetric piezoelectric materials. When a clicker is applied to the surface of the non-centrosymmetric hybrid organic-inorganic crystal synthesized in this invention, polarization occurs inside the crystal, and opposite charges appear on the two opposite surfaces of the crystal. The magnitude of the generated voltage signal can be observed by connecting an oscilloscope. When the positive and negative electrodes of the input terminal are swapped, the voltage signal reading on the oscilloscope changes to the opposite of the previous value. When the external force is removed, the crystal returns to an uncharged state, and the oscilloscope reading is zero. This invention demonstrates that the synthesized hybrid organic-inorganic crystal possesses piezoelectric properties. The synthesized hybrid organic-inorganic metal halide piezoelectric material exhibits high thermal stability primarily due to the cobalt ion serving as the central ion, which is connected to the chloride ion via a coordinate bond. To decompose it, the coordinate bond between the central ion and the chloride ion must first be broken, a process requiring significant heat. Furthermore, the ligands used in the synthesis are S,S-bis(α-methylbenzyl)amine hydrochloride and R,R-bis(α-methylbenzyl)amine hydrochloride, which possess substantial steric hindrance. Combining these two factors, the synthesized hybrid organic-inorganic metal halide piezoelectric material exhibits high thermal stability and displays a strong piezoelectric signal.

[0028] This invention involves dissolving a mixture of CoCl2·6H2O and an organic amine in acetonitrile, sonicating at room temperature until the solution gradually becomes clear, and then allowing it to stand at room temperature to evaporate the solvent. After several days, blue blocky crystals are obtained, which are then filtered and dried to obtain hybrid organic-inorganic crystals. This invention employs a room-temperature evaporation method, and the proposed preparation method is simple, efficient, and cost-effective. The target product has high purity, high thermal stability, and minimal environmental pollution, laying the foundation for the development and application of novel hybrid organic-inorganic materials in the field of sensing. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 The XRD patterns of two hybrid organic-inorganic metal halide piezoelectric materials in Embodiment 1 of the present invention are shown; where Obs = true value, Calc = calculated value, and Diff = the difference between the true value and the calculated value.

[0031] Figure 2 This is a structural diagram of two hybrid organic-inorganic metal halide piezoelectric materials from Embodiment 1 of the present invention;

[0032] Figure 3 Thermogravimetric diagrams of two hybrid organic-inorganic metal halide piezoelectric materials in Embodiment 1 of the present invention;

[0033] Figure 4 The images show the UV spectra of two hybrid organic-inorganic metal halide piezoelectric materials from Example 1 of this invention.

[0034] Figure 5 The following are circular dichroism chromatograms of two hybrid organic-inorganic metal halide piezoelectric materials from Example 1 of this invention;

[0035] Figure 6 This is a test diagram of the piezoelectric output performance of the hybrid organic-inorganic metal halide piezoelectric I powder of Example 1 of the present invention;

[0036] Figure 7 This is a test diagram of the piezoelectric output performance of the hybrid organic-inorganic metal halide piezoelectric material I-PVDF-TrFE composite nanofiber cloth of Example 1 of the present invention;

[0037] Figure 8 This is a test diagram of the piezoelectric output performance of the pure PVDF-TrFE nanofiber cloth in Example 1 of the present invention; Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0042] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0043] The hybrid organic-inorganic metal halide piezoelectric material prepared in this invention does not require expensive reaction equipment; the target product can be prepared in a regular laboratory using a small amount of raw materials. The method employed is a room-temperature solvent evaporation method, using acetonitrile as a benign solvent. This method has advantages such as simple operation, low cost, and no pollution.

[0044] This invention provides two hybrid organic-inorganic metal halide piezoelectric materials based on chiral regulation. These materials are synthesized using chiral organic amine ligands as raw materials, resulting in two hybrid organic-inorganic metal halide crystals exhibiting piezoelectric signals. Crystal I: S,S-bis(α-methylbenzyl)cobalt tetrachloride, chemical formula S,S-(PHA)₂CoCl₄; Crystal II: R,R-bis(α-methylbenzyl)cobalt tetrachloride, chemical formula R,R-(PHA)₂CoCl₄. Both hybrid organic-inorganic metal halide crystals are non-centrosymmetric, zero-dimensional bulk crystals with space group P21.

[0045] Crystal I: a=7.71150(10)Å b=22.0916(2)Å c=9.95360(10)Å, α=90°, β=105.3700(10)°, γ=90°;

[0046] Crystal II: a=7.70700(10) Å b=22.1249(2) Å c=9.94500(10) Å , α= 90 o , β=105.3540(2)°, γ= 90 o .

[0047] In this embodiment of the invention, the structure of the organic amine ligand is as follows:

[0048] and .

[0049] The technical solution of the present invention will be further explained below with reference to specific examples and accompanying drawings.

[0050] Example 1

[0051] Preparation of hybrid organic-inorganic metal halide piezoelectric materials: 10 mmol (2379.3 mg) of cobalt chloride hexahydrate was weighed and placed in a 25 mL beaker. 20 mL of acetonitrile was slowly added to the beaker using a pipette. The beaker was sealed and sonicated at room temperature for 2 min to completely dissolve the cobalt chloride hexahydrate. 20 mmol (5235.8 mg) of S,S-bis(α-methylbenzyl)amine hydrochloride was added, with a molar ratio of organic amine to cobalt chloride hexahydrate of 2:1. The mixture was sonicated at room temperature to dissolve the cobalt chloride, and then allowed to stand at room temperature for 2-3 days to obtain blue crystals. The crystals were dried in an oven at 55 °C for 6 h. The resulting product was the hybrid organic-inorganic metal halide piezoelectric material I.

[0052] Weigh 10 mmol (2379.3 mg) of cobalt chloride hexahydrate into a 25 mL beaker. Using a pipette, slowly add 20 mL of acetonitrile to the beaker, seal the container, and sonicate at room temperature for 2 min to completely dissolve the cobalt chloride hexahydrate. Add 20 mmol (5235.8 mg) of R,R-bis(α-methylbenzyl)amine hydrochloride, maintaining a molar ratio of organic amine to cobalt chloride hexahydrate of 2:1. Sonicate at room temperature to dissolve the solution, then allow it to stand at room temperature for 2-3 days to obtain blue crystals II. Dry the crystals in an oven at 55 °C for 6 h to obtain the target product, which is the hybrid organic-inorganic metal halide piezoelectric material II.

[0053] Two chiral hybrid organic-inorganic metal halide piezoelectric materials prepared in Example 1 were characterized by XRD powder diffraction, with a maximum voltage of 40 kV. The instrument was turned on, followed by the MiniFlex Guidance software for aging. The sample was placed on a clean silicon wafer, flattened with a scraper, and the "Door Lock" button was pressed. After two beeps, the chamber door was opened, the silicon wafer containing the sample was placed, and the chamber door was closed. The test conditions were set: scan speed of 5 deg / min, 2¢ for 5-30°, and the experimental values ​​were then refined using Topas. The results are as follows: Figure 1 As shown, Obs = actual value, Calc = calculated value, and Diff = the difference between the actual value and the calculated value. Figure 1 It is evident that the XRD patterns of the two crystals are almost identical to the theoretical calculations, indicating that the two crystals obtained have high purity. The structural diagrams of the two chiral hybrid organic-inorganic metal halide piezoelectric materials from Example 1 are shown below. Figure 2 .

[0054] The thermal stability of the two hybrid organic-inorganic metal halide piezoelectric materials prepared in Example 1 was tested using a thermogravimetric analyzer. 8 mg of each sample was weighed and the analysis was performed in air. The scan range was 28.7–800 °C, and the scan rate was 10 °C / min. The results are as follows: Figure 3 As shown, from Figure 3 It is evident from the results that the two crystals produced have excellent thermal stability, with decomposition temperatures of 244°C and 231°C.

[0055] The target product crystal I obtained in Example 1 was ground into small powder particles. Two 1.2g portions of (PVDF-TrFE) powder were weighed and placed in two 25mL beakers. 5mL of acetone and 5mL of N,N-dimethylformamide (DMF) were slowly added to the beakers using a pipette. The beakers were sealed with aluminum foil and stirred at room temperature until the PVDF-TrFE was completely dissolved in the acetone and DMF mixture. 60mg of S,S-bis(α-methylbenzyl)cobalt tetrachloride powder was added to one of the beakers, and the beakers were sealed with aluminum foil and stirred at room temperature until fully dispersed. After observing that the powder was fully dispersed in the solution, hybrid organic-inorganic metal halide piezoelectric-PVDF-TrFE composite nanofiber felt and pure PVDF-TrFE nanofiber felt were obtained using electrospinning technology. These were dried and ready for use.

[0056] Take 0.4 g of a powder sample of hybrid organic-inorganic metal halide piezoelectric material I, adhere conductive tape to both sides, and encapsulate it with PDMS / Kapton tape to create a simple sandwich piezoelectric device. Apply a mechanical stress of 10 Hz and 2 N to it using a clicker, and record the generated voltage signal using an oscilloscope. Figure 6 As shown, the complex exhibits a strong piezoelectric signal.

[0057] A hybrid organic-inorganic metal halide piezoelectric material-PVDF-TrFE composite fiber cloth was cut to a standard size of 2.5 cm * 2.5 cm. Nickel-copper-carbon cloth was adhered to the top and bottom surfaces of the fiber cloth as the top and bottom electrodes, respectively. The device was then encapsulated in PET film to obtain the test device. A 10 Hz clicker with a force of 5 N was used to mechanically excite the piezoelectric film, and its open-circuit voltage was measured using an oscilloscope. Figure 7 As shown, the hybrid organic-inorganic metal halide piezoelectric material-PVDF-TrFE composite fiber cloth exhibits a strong piezoelectric signal.

[0058] Pure PVDF-TrFE fiber cloth was cut to a standard size of 2.5 cm * 2.5 cm using an actuator. Nickel-copper carbon cloth was adhered to the top and bottom surfaces of the fiber cloth, and the device was encapsulated in PET film to obtain the test device. The piezoelectric film was mechanically excited using an actuator with a frequency of 10 Hz and a force of 5 N. The open-circuit voltage was measured using an oscilloscope. The triboelectric output performance test graph of the pure PVDF-TrFE fiber cloth is shown below. Figure 8 As shown, pure PVDF-TrFE fiber cloth has low piezoelectric properties.

[0059] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A hybrid organic-inorganic metal halide-like piezoelectric material based on chiral modulation, characterized in that, The material is a hybrid organic-inorganic metal halide crystal with piezoelectric signal synthesized using chiral organic amine ligands as raw materials. Crystal I: S,S-bis(α-methylbenzyl)cobalt tetrachloride, with the chemical formula S,S-(PHA)2CoCl4; Crystal II: R,R-bis(α-methylbenzyl)cobalt tetrachloride, with the chemical formula R,R-(PHA)2CoCl4. Both hybrid organic-inorganic metal halide crystals are non-centrosymmetric, zero-dimensional bulk crystals with space group P21. Crystal I: a=7.71150(10)Å b=22.0916(2)Å c=9.95360(10)Å, α=90°, β=105.3700(10)°, γ=90°; CrystalⅡ:a=7.70700(10) Å b=22.1249(2) Å c=9.94500(10) Å,α= 90 o , β=105.3540(2)°, γ= 90 o 。 2. The chiral-controlled hybrid organic-inorganic metal halide piezoelectric material according to claim 1, characterized in that, The structure of the organic amine ligand is as follows: and .

3. The chiral-controlled hybrid organic-inorganic metal halide piezoelectric material according to claim 1, characterized in that, The chiral-controlled organic-inorganic metal halide crystals are all blue transparent bulk crystals and all have piezoelectric properties.

4. The chiral-controlled hybrid organic-inorganic metal halide piezoelectric material according to claim 1, characterized in that, The decomposition temperature of metal halide crystal I is 244 ℃, and the decomposition temperature of perovskite crystal II is 231 ℃.

5. The chiral-controlled hybrid organic-inorganic metal halide piezoelectric material according to claim 1, wherein the chiral-controlled hybrid organic-inorganic metal halide piezoelectric material has a piezoelectric signal under the action of an clicker; the nanofiber cloth made by electrospinning the hybrid organic-inorganic metal halide piezoelectric material and PVDF-TrFE has a piezoelectric signal under the action of an clicker.

6. A method for synthesizing hybrid organic-inorganic metal halide crystals based on chiral regulation, characterized in that, Using acetonitrile as a solvent, and S,S-bis(α-methylbenzyl)amine hydrochloride and R,R-bis(α-methylbenzyl)amine hydrochloride as raw materials, two hybrid organic-inorganic metal halide crystals were obtained by dissolution, volatilization, and crystallization. The specific steps are as follows: Step 1: Dissolve cobalt chloride hexahydrate in acetonitrile and sonicate at room temperature to dissolve the cobalt chloride hexahydrate, obtaining solution A; Step 2: Add S,S-bis(α-methylbenzyl)amine hydrochloride and R,R-bis(α-methylbenzyl)amine hydrochloride to two bottles of solution A respectively to obtain solutions B and C. Stir ultrasonically for 20 minutes until completely dissolved to obtain clear blue solutions. Step 3: After solutions B and C are left to stand at room temperature for several days, the blue blocky crystals I and II described in claim 1 will precipitate. Step 4: Filter the bulk crystals I and II from Step 3 and place them in an oven to dry, thus obtaining two hybrid organic-inorganic metal halide crystals.

7. The method for synthesizing hybrid organic-inorganic metal halide crystals based on chiral regulation as described in claim 6, characterized in that, The molar ratio of organic amine and cobalt chloride hexahydrate used in the synthesis process is 2:

1.

8. The application of the hybrid organic-inorganic metal halide crystal obtained by the method of claim 6 or 7 in the field of sensors, characterized in that, Used for energy harvesting and ultrasonic detection.

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