A polar p-hydroxybenzoic acid single crystal, its preparation method and application

Abstract

The present invention relates to the technical field of benzoic acid single crystal cultivation, and particularly relates to a polar p-hydroxybenzoic acid single crystal, a preparation method thereof and an application thereof. Dissolve p-aminobenzamide in a solvent to obtain a saturated p-aminobenzamide solution; dissolve p-hydroxybenzoic acid in a solvent to obtain a saturated p-hydroxybenzoic acid solution; mix the saturated p-aminobenzamide solution and the saturated p-hydroxybenzoic acid solution, and let it stand to obtain a polar p-hydroxybenzoic acid single crystal. The preparation method of the present invention not only overcomes the structural limitations of the single solvent direct dissolution and recrystallization method, successfully obtains a p-hydroxybenzoic acid single crystal with a polar space group P21 structure, but also realizes the emergence of ferroelectricity in the p-hydroxybenzoic acid single crystal, opening up a new path for the development of the ferroelectric material field.

Description

Technical Field

[0001] The present invention relates to the technical field of benzoic acid single crystal cultivation, and particularly relates to a polar p-hydroxybenzoic acid single crystal, a preparation method thereof and an application thereof. Background Art

[0002] Ferroelectric materials have been widely applied in many fields due to their excellent optoelectronic properties. Designing and synthesizing complexes with polar space groups is a key prerequisite for improving the performance of ferroelectric materials. By carefully designing ligands with different structures and adopting ingenious complex assembly strategies, numerous ferroelectric compounds can be synthesized, such as various organic-inorganic hybrid ferroelectric materials.

[0003] In recent years, with the continuous exploration and in-depth study in the field of ferroelectric chemistry, pure organic ferroelectric materials have gradually become a research hotspot. In the existing preparation technologies, organic ferroelectric materials are usually prepared by directly dissolving them in a single solvent and then recrystallizing. For example, p-hydroxybenzoic acid is dissolved in ethanol, and then reacted at 150 °C under high pressure for 4 days, followed by the process of solvent evaporation and recrystallization. However, this method has the following defects: First, there is a structural limitation. By using the method of dissolving in a single solvent, reacting under high pressure and then recrystallizing, it is difficult to obtain organic ferroelectric materials with a polar space group structure, and only a non-polar P2 1 / n structure can be obtained. Second, the preparation conditions are harsh. High-pressure reactions have high requirements for experimental conditions, and precise control of temperature and pressure parameters is needed, which increases the complexity and cost of the experiment and is not conducive to large-scale production. Third, the performance of organic ferroelectric materials is unstable. Since a single solvent system cannot effectively control the crystal growth environment, it leads to defects and non-uniformity in the crystal structure, making the performance of ferroelectric materials unstable. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides a polar p-hydroxybenzoic acid single crystal, a preparation method thereof and an application thereof. The present invention introduces a saturated p-aminobenzamide solution into a saturated p-hydroxybenzoic acid solution, uses p-aminobenzamide as a regulator, significantly changes the chemical environment of the saturated p-hydroxybenzoic acid solution, and then controls the crystal growth process, and finally successfully prepares a polar p-hydroxybenzoic acid single crystal. The preparation method of the present invention not only overcomes the defect that is not conducive to large-scale production existing in the method of directly dissolving in a single solvent and then recrystallizing; moreover, the p-hydroxybenzoic acid single crystal obtained by the method of the present invention overcomes the structural limitation, successfully obtains a p-hydroxybenzoic acid single crystal with a polar space group P21 structure, reduces the defects and non-uniformity of the crystal structure, and also realizes the emergence of ferroelectricity in the p-hydroxybenzoic acid single crystal, opening up a new path for the development of the ferroelectric material field.

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

[0006] The first object of the present invention is to provide a method for preparing the above-mentioned polar p-hydroxybenzoic acid single crystal, which includes the following steps:

[0007] S1. Dissolve p-aminobenzamide in a solvent to obtain a saturated p-aminobenzamide solution.

[0008] S2. Dissolve p-hydroxybenzoic acid in a solvent to obtain a saturated p-hydroxybenzoic acid solution.

[0009] S3. Mix the saturated p-aminobenzamide solution and the saturated p-hydroxybenzoic acid solution, and let it stand at room temperature. During the standing process, the basic group in p-aminobenzamide and the acidic group in p-hydroxybenzoic acid form a complex through hydrogen bonding and electrostatic interaction. This interaction reduces the solubility of the saturated p-hydroxybenzoic acid and induces the p-hydroxybenzoic acid molecules to be oriented, obtaining the polar p-hydroxybenzoic acid single crystal.

[0010] Preferably, the molar ratio of p-aminobenzamide to p-hydroxybenzoic acid is 1:1 to 1.5.

[0011] Preferably, the solvents for dissolving p-aminobenzamide and p-hydroxybenzoic acid are the same.

[0012] Preferably, the standing condition is: standing at room temperature for 14 days to 20 days.

[0013] Preferably, the mass-volume ratio of p-aminobenzamide to methanol is 1.36 g to 1.38 g: 100 mL; among them, when the mass-volume ratio of p-aminobenzamide to methanol is 1.36 g: 100 mL, only a small amount of p-aminobenzamide in the saturated p-aminobenzamide solution is not dissolved; while when the mass-volume ratio of p-aminobenzamide to methanol is 1.38 g: 100 mL, it is observed that more p-aminobenzamide fails to dissolve completely.

[0014] Preferably, the solvent is selected from methanol, ethanol or acetonitrile.

[0015] The second object of the present invention is to provide the polar p-hydroxybenzoic acid single crystal prepared by the above-mentioned preparation method.

[0016] Preferably, the polar p-hydroxybenzoic acid single crystal is a colorless and transparent flaky crystal.

[0017] Preferably, the polar p-hydroxybenzoic acid single crystal has ferroelectricity.

[0018] The third object of the present invention is to provide the application of the above-mentioned polar p-hydroxybenzoic acid single crystal in the preparation of organic ferroelectric materials.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. The present invention provides a method for preparing a polar p-hydroxybenzoic acid single crystal. Dissolve p-aminobenzamide in a solvent to obtain a saturated p-aminobenzamide solution; dissolve p-hydroxybenzoic acid in a solvent to obtain a saturated p-hydroxybenzoic acid solution; mix the saturated p-aminobenzamide solution and the saturated p-hydroxybenzoic acid solution, and let it stand at room temperature. During the standing process, the basic group in p-aminobenzamide and the acidic group in p-hydroxybenzoic acid form a complex through hydrogen bonding and electrostatic interaction. This interaction reduces the solubility of the saturated p-hydroxybenzoic acid and induces the directional arrangement of p-hydroxybenzoic acid molecules, resulting in the formation of polar p-hydroxybenzoic acid single crystals. The present invention adopts an induced crystallization strategy. By introducing p-aminobenzamide as a regulator into the saturated p-hydroxybenzoic acid solution, it significantly changes the chemical environment of the saturated p-hydroxybenzoic acid solution, induces the formation of a polar lattice and reduces defects, while providing more crystallization driving force, thereby controlling the growth process of polar p-hydroxybenzoic acid single crystals and effectively improving the structural stability and performance uniformity of organic ferroelectric materials. The preparation method of the present invention not only overcomes the structural limitations of direct recrystallization after single solvent dissolution, successfully obtains p-hydroxybenzoic acid single crystals with a polar space group P21 structure, but also realizes the emergence of ferroelectricity in p-hydroxybenzoic acid single crystals, opening up a new path for the development of the ferroelectric material field.

[0021] 2. The polar p-hydroxybenzoic acid single crystal provided by the present invention has a polar space group P21 structure. This structural characteristic endows the polar p-hydroxybenzoic acid single crystal with ferroelectric properties. Specifically, the hydroxyl group and carboxyl group in the polar p-hydroxybenzoic acid single crystal molecule act together to form a distinct polar characteristic, prompting the molecules to be orderly arranged inside the crystal, and thus generating a spontaneous polarization phenomenon. Under the action of an external electric field, the electric dipole moments of these polar molecules are directionally arranged, thereby generating a macroscopic polarization effect and exhibiting good ferroelectric properties. In addition, the polar structure of the polar p-hydroxybenzoic acid single crystal also endows the polar p-hydroxybenzoic acid single crystal with good domain reversibility, providing a basis for the application of ferroelectric storage, such as room temperature ferroelectricity, making it have a broader application prospect in the fields of information storage, sensors, and optoelectronics.

[0022] 3. The preparation method of the present invention is simple to operate, does not require complex equipment and harsh experimental conditions, reduces the experimental cost, and improves the repeatability of the experiment and the feasibility of large-scale application. In addition, the method of the present invention is not only applicable to the p-hydroxybenzoic acid and p-aminobenzamide system, but also can be extended to the preparation of other organic, inorganic, and hybrid ferroelectric materials, and has wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is an ellipsoid diagram of the asymmetric unit of the polar p-hydroxybenzoic acid single crystal prepared in Example 1 of the present invention.

[0024] Figure 2 XRD pattern of the polar p-hydroxybenzoic acid single crystal prepared in Example 1 of the present invention.

[0025] Figure 3 Infrared spectrum of the polar p-hydroxybenzoic acid single crystal prepared in Example 1 of the present invention.

[0026] Figure 4 P-E curve of the polar p-hydroxybenzoic acid single crystal prepared in Example 1 of the present invention. Detailed implementation manners

[0027] The technical solutions of the present invention will be clearly and completely described below in combination with the data in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0028] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be obtained through market purchase or prepared by existing methods.

[0029] In the prior art, the preparation of organic ferroelectric materials such as p-hydroxybenzoic acid mainly relies on direct recrystallization after dissolving in a single solvent. There are many limitations in this method. First, due to the single nature of the solvent system, it is difficult to effectively control the crystal growth environment, resulting in the crystal structure often being limited to non-polar space groups and the ferroelectric properties being unsatisfactory. Second, direct recrystallization after dissolving in a single solvent has high requirements for experimental conditions and requires precise control of parameters such as temperature and pressure. This not only increases the complexity and cost of the experiment, but also limits the large-scale application of this method. In addition, due to the insufficient control ability of the single solvent system for crystal growth, defects and inhomogeneities often exist in the obtained crystals, resulting in unstable properties of the ferroelectric material and being difficult to meet the requirements of practical applications.

[0030] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for preparing polar p-hydroxybenzoic acid single crystals, which includes the following steps: Dissolve p-aminobenzamide in a solvent to obtain a saturated p-aminobenzamide solution; dissolve p-hydroxybenzoic acid in a solvent to obtain a saturated p-hydroxybenzoic acid solution; mix the saturated p-aminobenzamide solution and the saturated p-hydroxybenzoic acid solution, and let it stand at room temperature. During the standing process, the basic group in p-aminobenzamide and the acidic group in p-hydroxybenzoic acid form a complex through hydrogen bonding and electrostatic interaction. This interaction reduces the solubility of the saturated p-hydroxybenzoic acid and induces the p-hydroxybenzoic acid molecules to be arranged directionally, thereby obtaining polar p-hydroxybenzoic acid single crystals.

[0031] In view of the problem that it is difficult to obtain a polar space group structure by directly dissolving and recrystallizing with a single solvent, the present invention introduces p-aminobenzamide as a regulator into the solvent system, significantly changing the chemical environment of the solvent system, and then controlling the crystal growth process, and successfully obtaining p-hydroxybenzoic acid single crystals with a polar space group P21 structure.

[0032] In view of the problem that the traditional preparation method has high requirements for experimental conditions, resulting in increased experimental complexity and cost, the preparation method provided by the present invention is simple to operate, does not require complex equipment and harsh experimental conditions, and can obtain the required polar p-hydroxybenzoic acid single crystals only by standing at room temperature.

[0033] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with specific embodiments.

[0034] Example 1

[0035] A method for preparing polar p-hydroxybenzoic acid single crystals specifically includes the following steps:

[0036] S1. Dissolve 138.53 g (1.01 mol) of p-hydroxybenzoic acid in methanol to obtain a saturated methanol solution of p-hydroxybenzoic acid for standby; dissolve 137.82 g (1.01 mol) of p-aminobenzamide in methanol to obtain a saturated methanol solution of p-aminobenzamide for standby.

[0037] S2. Mix 50 mL of the saturated methanol solution of p-aminobenzamide and the saturated methanol solution of p-hydroxybenzoic acid according to a volume ratio of 1:1, filter, and let it stand for 14 days. After obvious crystals are formed, filter and wash to obtain polar p-hydroxybenzoic acid single crystals. The ellipsoid diagram of its asymmetric unit is as Figure 1 shown.

[0038] Example 2

[0039] A method for preparing a polar p-hydroxybenzoic acid single crystal, specifically comprising the following steps:

[0040] S1. Dissolve 138.53 g (1.01 mol) of p-hydroxybenzoic acid in methanol to obtain a saturated methanol solution of p-hydroxybenzoic acid for standby; dissolve 137.82 g (1.01 mol) of p-aminobenzamide in methanol to obtain a saturated methanol solution of p-aminobenzamide for standby.

[0041] S2. Mix 50 mL of the saturated methanol solution of p-aminobenzamide and the saturated methanol solution of p-hydroxybenzoic acid according to a volume ratio of 1:1, filter, and then let it stand for 20 days. After obvious crystals are formed, filter and wash to obtain the polar p-hydroxybenzoic acid single crystal.

[0042] Example 3

[0043] A method for preparing a polar p-hydroxybenzoic acid single crystal, specifically comprising the following steps:

[0044] S1. Dissolve 138.53 g (1.01 mol) of p-hydroxybenzoic acid in ethanol to obtain a saturated ethanol solution of p-hydroxybenzoic acid for standby; dissolve 137.82 g (1.01 mol) of p-aminobenzamide in ethanol to obtain a saturated ethanol solution of p-aminobenzamide for standby.

[0045] S2. Mix 50 mL of the saturated ethanol solution of p-aminobenzamide and the saturated ethanol solution of p-hydroxybenzoic acid according to a volume ratio of 1:1.5, filter, and then let it stand for 14 days. After obvious crystals are formed, filter and wash to obtain the polar p-hydroxybenzoic acid single crystal.

[0046] Example 4

[0047] A method for preparing a polar p-hydroxybenzoic acid single crystal, specifically comprising the following steps:

[0048] S1. Dissolve 138.53 g (1.01 mol) of p-hydroxybenzoic acid in acetonitrile to obtain a saturated acetonitrile solution of p-hydroxybenzoic acid for standby; dissolve 137.82 g (1.01 mol) of p-aminobenzamide in acetonitrile to obtain a saturated acetonitrile solution of p-aminobenzamide for standby.

[0049] S2. Mix 50 mL of the saturated acetonitrile solution of p-aminobenzamide and the saturated acetonitrile solution of p-hydroxybenzoic acid according to a volume ratio of 1:1, filter, and then let it stand for 14 days. After obvious crystals are formed, filter and wash to obtain the polar p-hydroxybenzoic acid single crystal.

[0050] Example 5

[0051] A method for preparing a polar p-hydroxybenzoic acid single crystal, specifically comprising the following steps:

[0052] S1. Dissolve 207.18 g of 1.5 mol of p-hydroxybenzoic acid in methanol to obtain a saturated methanol solution of p-hydroxybenzoic acid for standby; dissolve 137.82 g of 1.00 mol of p-aminobenzamide in methanol to obtain a saturated methanol solution of p-aminobenzamide for standby.

[0053] S2. Mix 50 mL of the saturated methanol solution of p-aminobenzamide and the saturated methanol solution of p-hydroxybenzoic acid according to a volume ratio of 1:1, filter, and then let it stand for 14 days. After obvious crystals are formed, filter and wash to obtain a polar p-hydroxybenzoic acid single crystal.

[0054] Comparative Example 1

[0055] A method for preparing a non-polar p-hydroxybenzoic acid single crystal, specifically comprising the following steps:

[0056] S1. Dissolve 138.53 g of 1.01 mol of p-hydroxybenzoic acid in methanol to obtain a saturated methanol solution of p-hydroxybenzoic acid.

[0057] S2. Slowly volatilize the solvent of the above-mentioned saturated methanol solution of p-hydroxybenzoic acid at room temperature. After standing for 14 days, when obvious crystals are formed, filter and wash to obtain a non-polar p-hydroxybenzoic acid single crystal.

[0058] Table 1 Data and Structure Refinement Parameters of the Polar p-Hydroxybenzoic Acid Single Crystal Prepared in Example 1

[0059]

[0060] The results in Table 1 show that the polar p-hydroxybenzoic acid single crystal prepared by the present invention belongs to the monoclinic system, space group P21, indicating that the symmetry of the polar p-hydroxybenzoic acid single crystal of the present invention is relatively low, a = 7.9359(4) Å, b = 5.2893(3) Å, c = 8.4552(4) Å, α = γ = 90°, β = 108.774(3)°, Z = 2.

[0061] From Figure 2 It can be obtained that the XRD pattern of the polar p-hydroxybenzoic acid single crystal of the present invention, presented as a black curve, is basically consistent with the simulated XRD pattern, presented as a red curve, in terms of the position and relative intensity of the diffraction peaks, indicating the high purity and correct crystal structure of the polar p-hydroxybenzoic acid single crystal prepared in Example 1 of the present invention.

[0062] From Figure 3 It can be obtained that through infrared spectroscopy analysis, 3465 cm -1 、3323 cm -1and 3209 cm -1 The absorption peak at -1 belongs to the O-H stretching vibration, revealing the presence of hydroxyl groups (-OH) in the polar p-hydroxybenzoic acid single crystal molecules of the present invention. The absorption peaks at 1660 cm -1 and 1615 cm -1 are attributed to the C=O stretching vibration, further confirming the presence of carboxyl groups (-COOH). The absorption peaks at 1598 cm -1 and 1563 cm -1 are related to the C=C stretching vibration of the benzene ring, reflecting the structural characteristics of the aromatic ring. The absorption peaks at 1434 cm -1 and 1394 cm -1 correspond to the bending vibration of C-H, further supporting the presence of the benzene ring. The absorption peaks at 1290 cm -1 and 1153 cm -1 are related to the C-O stretching vibration, consistent with the C-O bond in the carboxyl group. The absorption peaks at 851 cm -1 and 784 cm -1 are related to the out-of-plane bending vibration of C-H. These characteristic peaks are in agreement with the molecular structure of p-hydroxybenzoic acid, verifying its chemical composition.

[0063] It is obtained from Figure 4 that it exhibits obvious non-linear characteristics, indicating that the polar p-hydroxybenzoic acid single crystal prepared by the present invention has significant ferroelectricity. As the electric field strength increases, the polarization intensity gradually increases and saturates at high electric field strengths, further verifying the polarization response characteristics of the polar p-hydroxybenzoic acid single crystal molecules under the action of an electric field. Specifically, the saturation polarization intensity (P s ) of this sample is 1.61 μC / cm 2 , the remanent polarization intensity (P r ) is 0.20 μC / cm 2 , and the coercive field (E c ) is 0.46 kV / cm. These parameters are all in line with the typical characteristics of ferroelectric materials.

[0064] It should be noted that when numerical ranges are involved in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods adopted are the same as those in the embodiments, to avoid redundancy, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0065] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for preparing a polar p-hydroxybenzoic acid single crystal, characterized in that, It includes the following steps: Dissolve p-aminobenzamide in a solvent to obtain a saturated p-aminobenzamide solution; Dissolve p-hydroxybenzoic acid in a solvent to obtain a saturated p-hydroxybenzoic acid solution; Mix the saturated p-aminobenzamide solution and the saturated p-hydroxybenzoic acid solution, and let it stand at room temperature. During the standing process, the basic group in p-aminobenzamide and the acidic group in p-hydroxybenzoic acid form a complex through hydrogen bonding and electrostatic interaction, inducing the p-hydroxybenzoic acid molecules to be oriented, and obtaining polar p-hydroxybenzoic acid single crystals.

2. The preparation method of the polar p-hydroxybenzoic acid single crystal according to claim 1, characterized in that, The molar ratio of p-aminobenzamide to p-hydroxybenzoic acid is 1:1 to 1.

5.

3. The preparation method of the polar p-hydroxybenzoic acid single crystal according to claim 1, characterized in that, The solvents for dissolving p-aminobenzamide and p-hydroxybenzoic acid are the same.

4. The method for preparing a polar p-hydroxybenzoic acid single crystal according to claim 3, characterized in that, The solvent is selected from methanol, ethanol or acetonitrile.

5. A polar p-hydroxybenzoic acid single crystal, characterized in that, The polar p-hydroxybenzoic acid single crystal is prepared by the preparation method described in any one of claims 1 to 4.

6. The p-hydroxybenzoic acid single crystal according to claim 5, characterized in that, The polar p-hydroxybenzoic acid single crystal is a colorless transparent flaky crystal.

7. The p-hydroxybenzoic acid single crystal according to claim 5, characterized in that The polar p-hydroxybenzoic acid single crystal has ferroelectricity.

8. Use of the polar p-hydroxybenzoic acid single crystal according to claim 5 in the preparation of organic ferroelectric materials.

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