Organic-inorganic hybrid malonate polar crystal material as well as preparation method and application thereof

Abstract

The invention discloses an organic-inorganic hybrid malonate polar crystal material as well as a preparation method and application thereof, and belongs to the technical field of optical crystal materials. The chemical formula of the organic and inorganic hybrid malonate polar crystal material is RbLi (C3H2O4). H2O. The invention further discloses a preparation method of the organic and inorganic hybrid malonate polar crystal material. The invention also discloses a preparation method and application of the organic-inorganic hybrid malonate polar crystal material. According to the crystal material, flexible malonic acid radical anions are used as polar functional elements, the malonic acid radical is effectively induced to generate moderate structural distortion by utilizing a synergistic cation regulation strategy of Rb < + > and Li < + >, so that the crystal is stably crystallized in a polar space group, and meanwhile, the crystal material shows excellent nonlinear optical performance and is wide in application prospect.

Description

Technical Field

[0001] This invention belongs to the field of optical crystal materials technology, specifically relating to organic-inorganic hybrid malonate polar crystal materials, their preparation methods, and applications. Background Technology

[0002] Polar crystal materials are characterized by the alignment of positive and negative ions along a specific direction to form a polar axis, exhibiting unique optical properties. When subjected to an external field, polar crystal materials display piezoelectricity, pyroelectricity, ferroelectricity, and nonlinear optical (NLO) effects. Therefore, polar crystal materials are an indispensable part of core technology fields such as sensor technology, optoelectronics, data storage, and energy conversion. However, due to the strict symmetry requirements of polar crystals, target crystals exhibiting excellent optical performance remain extremely rare. Specifically, only 29.6% of the 230 space groups allow for polarity, which inherently limits the number of candidate structures. Furthermore, among these limited polar crystals, those that simultaneously meet the performance and stability requirements for commercial applications are even fewer. Therefore, designing and synthesizing novel polar crystals with superior performance is particularly crucial.

[0003] In recent years, those skilled in the art have commonly used polar functional basic modules to guide the assembly of polar crystals. In this strategy, π-conjugated planar groups and non-π-conjugated polyhedral groups are often used as ideal functional basic modules. Benefiting from their high hyperpolarizability and significant polarizability anisotropy, π-conjugated planar groups can derive crystal materials with excellent nonlinear optical properties such as strong second harmonic response (SHG) and large birefringence (Δn). However, due to their inherent high symmetry and strong intramolecular interactions, rigid π-conjugated planar groups often lead to crystallization in nonpolar space groups, thus limiting their potential application as polar devices. On the other hand, while some polar compounds containing non-π-conjugated polyhedral groups can break symmetry constraints and exhibit good polar characteristics, their crystals are usually small in size and have poor growth habits, making it difficult to prepare large-size, high-quality single crystals using conventional methods, severely restricting their practical application in commercial devices. Therefore, exploring the synthesis of high-performance polar crystals is of great significance. Summary of the Invention

[0004] The problem to be solved by this invention is to provide an organic-inorganic hybrid malonate polar crystal material, its preparation method and application. The crystal material can be stably crystallized in the polar space group, has excellent nonlinear optical properties, and has a convenient synthesis route and good crystal quality.

[0005] The technical solution adopted to solve its technical problem is to provide an organic-inorganic hybrid malonate polar crystal material, the chemical formula of which is RbLi(C3H2O4)·H2O.

[0006] Preferably, the organic-inorganic hybrid malonate polar crystal material is a nonlinear optical crystal, belonging to the orthorhombic crystal system, with space group Pna21, and cell parameters a = 8.7610(5) Å, b = 7.5982(5) Å, c = 9.4710(7) Å, α = 90°, β = 90°, γ = 90°.

[0007] This invention also provides a method for preparing the above-mentioned organic-inorganic hybrid malonate polar crystal material, comprising the following steps: Lithium hydroxide monohydrate, rubidium chloride, and malonic acid are mixed to obtain a mixture. The mixture is then added to water and subjected to a water bath reaction. After cooling to room temperature, the precipitated solid is the organic-inorganic hybrid malonate polar crystal material.

[0008] Preferably, the molar ratio of lithium hydroxide monohydrate, rubidium chloride, and malonic acid is 2:1:1.

[0009] Preferably, the mass ratio of the mixture to water is (2000~2200):1600.

[0010] More preferably, the mass ratio of the mixture to water is 2162.86:1600.

[0011] Preferably, the pH of the water bath reaction is 7~7.5, the temperature is 35~45℃, and the time is 5~7h.

[0012] More preferably, the pH of the water bath reaction is 7.02, the temperature is 40°C, and the time is 6 hours.

[0013] Preferably, the cooling rate is 15~25℃ / h.

[0014] More preferably, the cooling rate is 20°C / h.

[0015] This invention also provides the application of the above-mentioned organic-inorganic hybrid malonate polar crystal material in the preparation of optical polarization elements.

[0016] The present invention has the following beneficial effects: This invention successfully prepared polar malonate crystals RbLi(C3H2O4)·H2O using an aqueous solution method; the crystals contain flexible malonate anions (C3H2O4). 2- ) as a polar functional unit, and utilizing Rb + With Li +The synergistic cation regulation strategy effectively induces moderate structural distortion of the malonate anion, thereby enabling the crystal to crystallize stably in the polar space group and exhibiting excellent nonlinear optical properties. RbLi(C3H2O4)·H2O has a short ultraviolet absorption cutoff edge, a large birefringence, and a strong frequency doubling effect; this compound not only expands the structural diversity of polar malonate systems, but also provides a potential candidate for the development of polar crystal materials that can be used in laser frequency conversion, optoelectronic modulation, and other fields. Attached Figure Description

[0017] Figure 1 A schematic diagram of the crystal structure of RbLi(C3H2O4)·H2O; Figure 2 The X-ray powder diffraction pattern of RbLi(C3H2O4)·H2O crystal in Example 1 is shown below. Figure 3 Thermogravimetric analysis curve of RbLi(C3H2O4)·H2O crystal in Example 1; Figure 4 The infrared spectrum of RbLi(C3H2O4)·H2O crystal in Example 1 is shown below. Figure 5 The UV-vis diffuse reflectance spectrum of the RbLi(C3H2O4)·H2O crystal in Example 1 is shown. Figure 6 The figure shows the theoretically calculated birefringence values ​​of the RbLi(C3H2O4)·H2O crystal in Example 1. Figure 7 The image shows the birefringence test results of the RbLi(C3H2O4)·H2O crystal in Example 1; where (a) is the interference color diagram of the crystal under a polarizing microscope; (b) is the crystal thickness measurement result; (c) is the extinction diagram of the crystal when the compensator is rotated clockwise; and (d) is the extinction diagram of the crystal when the compensator is rotated counterclockwise. Figure 8 The diagrams show the frequency doubling effect and phase matching results of the RbLi(C3H2O4)·H2O crystal in Example 1; where (a) is the frequency doubling effect diagram and (b) is the phase matching result diagram. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments.

[0019] Example 1 The organic-inorganic hybrid malonate polar crystal material has the chemical formula RbLi(C3H2O4)·H2O. It is a nonlinear optical crystal, belonging to the orthorhombic crystal system, with space group Pna21 and cell parameters a = 8.7610(5) Å, b = 7.5982(5) Å, c = 9.4710(7) Å, α = 90°, β = 90°, γ = 90°.

[0020] This embodiment also includes a method for preparing the above-mentioned organic-inorganic hybrid malonate polar crystal material, comprising the following steps: Lithium hydroxide monohydrate, rubidium chloride, and malonic acid were mixed in a molar ratio of 2:1:1 to obtain a mixture. 2162.86g of the mixture was added to 1600g of high-purity water and reacted in a water bath at pH 7.02 and 40℃ for 6h. After cooling to room temperature at a rate of 20℃ / h, the precipitated transparent and colorless blocky product was washed with acetone and dried to obtain blocky and colorless RbLi(C3H2O4)·H2O crystals.

[0021] Example 2 In this embodiment, the organic-inorganic hybrid malonate polar crystal material is the same as that in Example 1.

[0022] This embodiment also includes a method for preparing the above-mentioned organic-inorganic hybrid malonate polar crystal material, comprising the following steps: Lithium hydroxide monohydrate, rubidium chloride, and malonic acid were mixed in a molar ratio of 2:1:1 to obtain a mixture. 2000g of the mixture was added to 1600g of high-purity water and reacted in a water bath at pH 7 and 35℃ for 7h. After cooling to room temperature at a rate of 15℃ / h, the precipitated transparent and colorless blocky product was washed with acetone and dried to obtain blocky and colorless RbLi(C3H2O4)·H2O crystals.

[0023] Example 3 In this embodiment, the organic-inorganic hybrid malonate polar crystal material is the same as that in Example 1.

[0024] This embodiment also includes a method for preparing the above-mentioned organic-inorganic hybrid malonate polar crystal material, comprising the following steps: Lithium hydroxide monohydrate, rubidium chloride, and malonic acid were mixed in a molar ratio of 2:1:1 to obtain a mixture. 2200g of the mixture was added to 1600g of high-purity water and reacted in a water bath at pH 7.5 and 45℃ for 5h. After cooling to room temperature at a rate of 25℃ / h, the precipitated transparent and colorless blocky product was washed with acetone and dried to obtain blocky and colorless RbLi(C3H2O4)·H2O crystals.

[0025] Experimental Example 1. Crystal structure of RbLi(C3H2O4)·H2O The crystal structure of RbLi(C3H2O4)·H2O was analyzed, and the results are as follows: Figure 1 As shown.

[0026] The RbLi(C3H2O4)·H2O crystal obtained in Example 1 of this invention belongs to the orthorhombic crystal system with polar space group Pna21. Figure 1 As can be seen from this, its structural framework consists of [C3H2O4]. 2- Flexible group, [LiO4] 7- Polyhedra and Rb + It is composed of interconnected cations; C3H4O4 is formed by double deprotonation to form [C3H2O4]. 2- Groups, via Rb + With Li + The synergistic cation regulation induced a moderate structural distortion of the malonate ion, resulting in rotation angles α and dihedral angles β of 109.93° and 76.54°, respectively. Furthermore, [LiO4] 7- The polyhedron is obtained through interaction with [C3H2O4]. 2- The groups share O atoms to form a three-dimensional framework structure, and Rb atoms are neatly located in the gaps of the framework structure as charge compensators.

[0027] 2. X-ray diffraction analysis X-ray diffraction analysis of RbLi(C3H2O4)·H2O in Example 1 was performed using a Miniflex-600 powder X-ray diffractometer. The scanning step size was 0.08°, the 2θ angle range was 5~70°, and the step size was 0.2s. The results are as follows: Figure 2 As shown.

[0028] Through the Figure 2 The comparison of each diffraction peak in the experimental test (red line) and the software fitting (black line) revealed that the peak positions of the experimental spectrum and the fitted spectrum of compound RbLi(C3H2O4)·H2O were in good agreement, indicating that the synthesized crystal was a pure phase.

[0029] 3. Thermogravimetric analysis Thermogravimetric analysis of RbLi(C3H2O4)·H2O in Example 1 was performed using a Netzsch STA449F3 thermometer. The sample was heated from room temperature to 700°C at a heating rate of 10°C / min. The results are as follows: Figure 3 As shown.

[0030] from Figure 3 As can be seen, the compound RbLi(C3H2O4)·H2O only begins to lose weight when heated to around 100℃, indicating good thermal stability.

[0031] 4. Infrared spectroscopy analysis The infrared spectrum of RbLi(C3H2O4)·H2O in Example 1 was analyzed using a Vertex 70 Fourier transform infrared (FT-IR) spectrometer with a resolution of 4 cm⁻¹. -1 The spectral range is 400~4000 cm⁻¹ -1 The result is as follows Figure 4 As shown.

[0032] from Figure 4 As can be seen, the strong absorption peak appears at 1591 cm⁻¹. -1 This is attributed to the stretching vibration of the C=O bond; the second strongest absorption peak is located at 1344 cm⁻¹. -1 This corresponds to the stretching vibration of the CO bond; 3303 / 3150 cm⁻¹ -1 The peaks at that location are attributed to the bending vibrations of the OH bonds. These characteristic peaks are related to the malonic acid ligand ([C3H2O4]) in the compound. 2- The vibrational modes of the functional groups of the molecules are consistent with those of water molecules, which verifies the presence of carboxylate and hydroxyl groups in its molecular structure.

[0033] 5. UV-Vis diffuse reflectance spectral analysis The UV-Vis diffuse reflectance spectra of RbLi(C3H2O4)·H2O from Example 1 were analyzed using a PerkinElmer Lamda-950 UV / Vis / NIR spectrophotometer to obtain the compound's UV-Vis diffuse reflectance. The scanning range was 190–800 nm. The reflectance values ​​were converted to absorbance-Munk functions using Kubelka. The results are as follows: Figure 5 As shown.

[0034] Figure 5 The compound exhibits a band gap of 5.29 eV and a corresponding cutoff edge of 219 nm, indicating its potential application in short-wave ultraviolet light.

[0035] 6. Birefringence analysis Density functional theory (DFT) was used to theoretically calculate the birefringence of RbLi(C3H2O4)·H2O in Example 1. The birefringence of RbLi(C3H2O4)·H2O in Example 1 was experimentally measured using a Zeiss polarizing microscope (Axio A5). The results are as follows: Figures 6-7 As shown.

[0036] from Figures 6-7As can be seen, the theoretically calculated birefringence of compound RbLi(C3H2O4)·H2O is 0.168@546 nm; the measured birefringence of RbLi(C3H2O4)·H2O is 0.163@546 nm. This birefringence originates from the [C3H2O4] in the crystal. 2- The conjugated π-electron system of functional groups and [LiO4] 7- The anisotropy of polarizability arises from the ordered arrangement of polyhedra. The theoretical value is close to the experimental value of 0.163@546nm, verifying the reliability of the calculation model and indicating that its birefringence characteristics can be controlled by structural distortion, making it suitable for the design of optical polarization elements.

[0037] 7. Analysis of the second-order harmonic effect The second-order harmonic effect of RbLi(C3H2O4)·H2O in Example 1 was measured using the Kurtz-Perry method under 1064 nm laser irradiation, with KDP as a reference. The results are as follows: Figure 8 As shown.

[0038] like Figure 8 As shown in (a), the SHG signal intensity of RbLi(C3H2O4)·H2O measured in particle sizes of 150–212 μm is approximately 3.0 × KDP; Figure 8 As shown in (b), the compound exhibits type I phase matching. Therefore, RbLi(C3H2O4)·H2O demonstrates excellent nonlinear optical properties and has the potential for application as a polar crystal.

[0039] The present invention has been described according to the above embodiments. It should be understood that the above embodiments do not limit the present invention in any way. All technical solutions obtained by equivalent substitution or equivalent transformation fall within the scope of the present invention.

Claims

1. An organic-inorganic hybrid malonate polar crystalline material characterized in that, The chemical formula of the organic-inorganic hybrid malonate polar crystal material is RbLi(C3H2O4)·H2O.

2. The organic-inorganic hybrid malonate polar crystalline material of claim 1, wherein, The organic-inorganic hybrid malonate polar crystal material is a nonlinear optical crystal, belongs to an orthorhombic system, a space group is Pna21, and cell parameters are a = 8.7610(5) Å, b = 7.5982(5) Å, c = 9.4710(7) Å, α = 90°, β = 90°, and γ = 90°.

3. The method for producing the organic-inorganic hybrid malonate polar crystal material according to any one of claims 1 to 2, characterized by, The method comprises the following steps: Lithium hydroxide monohydrate, rubidium chloride and malonic acid are mixed to obtain a mixture; the mixture is added into water and subjected to a water bath reaction, and after being cooled to room temperature, a solid separated out is the organic-inorganic hybrid malonate polar crystal material.

4. The method for preparing the organic-inorganic hybrid malonate polar crystal material as described in claim 3, characterized in that, The molar ratio of the lithium hydroxide monohydrate, the rubidium chloride and the malonic acid is 2:1:

1.

5. The method of producing an organic-inorganic hybrid malonate polar crystal material according to claim 3, wherein The mass ratio of the mixture to water is (2000-2200):1600.

6. The method of producing an organic-inorganic hybrid malonate polar crystal material according to claim 5, wherein The mass ratio of the mixture to water is 2162.86:1600.

7. The method of producing an organic-inorganic hybrid malonate polar crystal material according to claim 3, wherein The pH of the water bath reaction is 7-7.5, the temperature is 35-45 ℃, and the time is 5-7 h.

8. The method of producing an organic-inorganic hybrid malonate polar crystal material according to claim 7, wherein The pH of the water bath reaction is 7.02, the temperature is 40 ℃, and the time is 6 h.

9. The method of producing an organic-inorganic hybrid malonate polar crystal material according to claim 3, wherein The cooling rate is 15-25 ℃ / h.

10. Use of the organic-inorganic hybrid malonate polar crystal material in any one of claims 1-2 in preparation of an optical polarization element.

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