A chiral zinc complex crystal with second-order nonlinear and birefringence properties and a preparation method thereof

Abstract

The application provides a chiral zinc complex crystal with second-order nonlinearity and birefringence performance, characterized by a molecular formula; the chiral zinc complex crystal belongs to an orthorhombic system, a space group is Pca21, and is a non-central symmetric structure; the chiral zinc complex crystal has second-order nonlinearity and birefringence performance. The application also provides a preparation method of the chiral zinc complex crystal, and solves the problem that the crystal is easy to form a central symmetric structure in the prior art; the method is characterized by inducing a chiral small molecule with intrinsic non-central symmetry, and combining the advantages of non-d-d electron transition absorption, so that the crystal forms a non-central symmetric orthorhombic system structure, the crystal is ensured to have stable second-order nonlinearity, and meanwhile, a suitable birefringence is obtained, so that the core requirements of laser frequency conversion and phase matching are met.

Description

Technical Field

[0001] This invention relates to the field of optical materials technology, specifically to a chiral zinc complex crystal and its preparation method. Background Technology

[0002] Second-order nonlinear optical crystals are core materials for laser frequency conversion, effectively extending the output wavelength of solid-state lasers and playing a crucial role in optical communication, spectral analysis, and terahertz wave generation. The performance of these crystals depends on their non-centrosymmetric structure and optical anisotropy. However, during growth, these crystals tend to gravitate towards a thermodynamically stable centrosymmetric structure, leading to a lack of second-order nonlinear effects; furthermore, achieving synergistic optimization of large frequency doubling coefficients and high birefringence remains challenging.

[0003] Zinc complexes are composed of divalent zinc ions ( ) is the central atom, because With stable The electronic configuration prevents dd transitions in its complexes, resulting in a wide optical transmission window that effectively avoids the impact of dd absorption on the crystal's optical properties; simultaneously, Zinc complexes can form structurally diverse and stable complexes with various organic or inorganic ligands, significantly enhancing second-order nonlinear optical effects. Although zinc complexes have made significant progress in second-order nonlinear optics research, how to fully utilize the intrinsic noncentrosymmetry of chiral molecules and... of The ability to optimize the configuration, directionally control the arrangement of molecules in a crystal, break the centrosymmetric structure, and thus prepare crystals with both excellent second-order nonlinearity and birefringence remains a key scientific problem that urgently needs to be solved in this field.

[0004] Therefore, this patent application provides a chiral stacking method that utilizes chiral small molecules to induce crystal structures, thereby preparing chiral zinc complex optical crystal materials with excellent optical properties.

[0005] Currently, the main methods for preparing zinc complex nonlinear optical crystals in existing technologies are conventional coordination reactions combined with crystal growth. Common ligands are typically selected to coordinate with zinc salts, and crystals are grown via solution or melt methods. The core idea of ​​these methods is to utilize the coordination between ligands and zinc ions to form a complex, and then obtain the crystal by controlling the growth conditions.

[0006] Currently, most of the related technologies in this field are general coordination crystal preparation methods, widely used in the synthesis of zinc complex crystals. Related research results can be found in journals such as the *Journal of Inorganic Chemistry* and *Coordination Chemistry*, as well as in relevant patent literature. Specifically, in patents CN119061482A and CN119065174A, the synthesis of zinc complex single crystals mainly uses the conventional ligand thiocyanate.

[0007] The core drawback of this existing technical solution is that conventional ligands lack chiral structures and intrinsic noncentrosymmetry. This prevents the method from effectively controlling molecular packing through chiral induction, leading to the formation of centrosymmetric structures in the crystals. Consequently, the crystals lose their optical anisotropy, resulting in the absence of second-order nonlinearity and birefringence. Furthermore, the existing technology does not fully utilize... of While optimizing the advantages of electronic structure configuration, it is difficult to achieve a synergistic improvement in crystal optical transparency and core optical performance. As a result, the crystal's optical performance is limited, and its application scenarios are relatively narrow. Summary of the Invention

[0008] The purpose of this invention is to provide a chiral zinc complex crystal with both second-order nonlinearity and birefringence properties and its preparation method, effectively solving the problems in the background art.

[0009] The first aspect of this invention provides a chiral zinc complex crystal with the molecular formula: The chiral zinc complex crystal belongs to the orthorhombic crystal system, with space group [missing information]. It is a non-centrosymmetric structure; it possesses second-order nonlinear effects and birefringence properties.

[0010] According to a second aspect of the present invention, a method for preparing chiral zinc complex crystals is provided, comprising the following steps: (1) Mix the chiral ligand and zinc salt, grind them thoroughly in a mortar until they are evenly mixed, and obtain a white powder; (2) Add a polar organic solvent to step one and stir until it is completely dissolved to provide a homogeneous reaction system for the coordination reaction; (3) Continue to add non-polar solvent to step two and stir the reaction for the preset time, then filter into a beaker; (4) Seal the opening with plastic wrap, punch holes and let it stand for 3 to 6 days to allow natural evaporation and crystal growth to obtain chiral zinc complex crystals.

[0011] Preferably, the chiral ligand is chiral diphenylethylenediamine; the zinc salt has electronic configuration The chiral diphenylethylenediamine is (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine; its structural formula is: .

[0012] Preferably, the zinc salt is one or a combination of zinc chloride, zinc perchlorate hexahydrate, and zinc nitrate hexahydrate.

[0013] Preferably, the polar organic solvent is acetone; The nonpolar solvent is n-hexane.

[0014] Preferably, the polar organic solvent is methanol; The nonpolar solvent is dichloromethane.

[0015] Preferably, the polar organic solvent is methanol; The nonpolar solvent is acetone.

[0016] Preferably, the grinding time in the mortar is at least 1 hour; Add a polar organic solvent and stir for at least 10 minutes; Add a non-polar solvent and stir for at least 10 minutes.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This method primarily introduces a chiral source into the molecular framework, utilizing the inherent noncentrosymmetry of chiral molecules and the synergistic effect of weak intermolecular interactions to induce the crystal to form a stable noncentrosymmetric space group, thereby ensuring the realization of macroscopic second-order nonlinear effects from the source. Simultaneously, by introducing [a chiral source] into the molecular framework... Conjugated systems can significantly enhance intramolecular charge transfer efficiency, improve the microscopic second-order polarizability of molecules, and enhance the anisotropy of polarizability in molecular arrangement, thereby synergistically improving the nonlinear optical response and birefringence properties of materials, laying the foundation for achieving efficient optical frequency conversion and polarization control. Based on this, utilizing the diversity of metal coordination geometries (tetrahedral, octahedral, etc.) and good optical transparency windows, chiral metal complexes with tunable structures and excellent performance can be constructed, potentially yielding novel second-order nonlinear optical crystal materials that combine large nonlinear coefficients, suitable birefringence, high thermal stability, and good crystal growth capabilities.

[0018] 2. By utilizing the chiral amine group in the diphenylethylenediamine molecule to coordinate with zinc ions, a metal-organic hybrid unit with a defined coordination configuration is formed. This can be achieved by altering the type of anion in the zinc salt (e.g., ...). , , By regulating the coordination environment and geometric configuration of the zinc center, crystal structures of various coordination polyhedra, such as tetrahedrons, square pyramids, and octahedrons, can be obtained.

[0019] 3. The single configuration of the chiral ligand (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine induces directional molecular stacking, binding... The coordination with N atoms in the ligands forms an orthorhombic crystal structure without a center of symmetry, providing structural protection for second-order nonlinear effects and birefringence properties; specific cell parameters determine the optical anisotropy of the crystal, which in turn affects the birefringence and phase matching ability.

[0020] 4. The chiral center of diphenylethylenediamine is transferred to the entire metal-organic framework through coordination bonds, guiding the molecule to arrange itself in a non-centrosymmetric manner, thereby effectively preventing dipole cancellation and providing structural assurance for achieving second-order nonlinear optical effects and birefringence. (This point (point 4) is redundant with point 3 and should be deleted.)

[0021] 5. Zinc salts Its electronic configuration has a stable A full-shell electron configuration can avoid dd transitions, which is beneficial for widening the optical bandgap. It is transparent in the ultraviolet-visible region and is conducive to the design of wide bandgap and high transmittance materials. Attached Figure Description

[0022] Figure 1 Optical photograph of the chiral zinc complex crystal prepared in Example 1; Figure 2 Asymmetric units of the chiral zinc complex crystals prepared in Example 1; Figure 3 Simulated XRD pattern and XRD pattern after grinding into powder, showing the chiral zinc complex crystals prepared in Example 1; Figure 4 The infrared spectrum of the chiral zinc complex crystal prepared in Example 1; Figure 5 The ultraviolet-visible-near-infrared spectrum of the chiral zinc complex crystals prepared in Example 1; Figure 6 Tauc method fitting diagram of the chiral zinc complex crystals prepared in Example 1; Figure 7 The TG-DSC analysis result of the chiral zinc complex crystals prepared in Example 1; Figure 8 The second harmonic intensity of the chiral zinc complex crystal prepared in Example 1 under a 1064 nm incident laser. Figure 9 The second harmonic phase-matching curve data of the chiral zinc complex crystal prepared in Example 1 under 1064 nm incident laser light; Figure 10 The extinction pattern was obtained by rotating the chiral zinc complex crystals prepared in Example 1 along the positive rotation axis. Figure 11 The extinction pattern was achieved by the negative rotation axis of the chiral zinc complex crystals prepared in Example 1; Figure 12 Thickness diagram of the chiral zinc complex crystals prepared in Example 1; Figure 13 The birefringence diagram of the chiral zinc complex crystal prepared in Example 1 is calculated based on theoretical calculations. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The present invention will be further explained below with reference to specific embodiments.

[0025] Example 1: The chiral zinc complex provided by this invention has the following molecular formula: This crystal belongs to the orthorhombic crystal system, with space group . Its unit cell parameters are , , , , , This orthorhombic crystal system is a non-centrosymmetric structure, which is the structural basis for the crystal's second-order nonlinear effect and birefringence. Its structural advantages mainly stem from the intrinsic non-centrosymmetry of the chiral ligands and... The coordination regulation effect.

[0026] A method for preparing chiral zinc complexes, comprising the following steps: (1) Chiral diphenylethylenediamine and zinc chloride are mixed in a molar ratio of 1:1 and ground thoroughly in an agate mortar to obtain a white powder.

[0027] In practice, the purpose of grinding is to ensure that the chiral ligands are in full contact with the zinc salt, laying the foundation for subsequent coordination reactions and ensuring that the crystal can form a stable non-centrosymmetric structure.

[0028] (2) Add acetone to step one and stir for 10 min to dissolve it completely.

[0029] In practice, acetone, as a polar organic solvent, can effectively dissolve chiral diphenylethylenediamine and zinc chloride, providing a homogeneous reaction system for the coordination reaction.

[0030] (3) Continue adding n-hexane to the mixture from step two and stir for 10 min. Filter the mixture into a beaker, seal it with plastic wrap, poke holes in the wrap, and let it stand to allow natural evaporation for 3-4 days. Crystal growth will then occur, yielding chiral zinc complex crystals, denoted as […]. Crystal.

[0031] In practice, hexane, as a non-polar solvent, can be added to adjust the polarity of the mixed solvent, promote the crystallization of the complex, and the perforation of the plastic wrap can control the solvent evaporation rate, ensure slow crystal growth, and improve the purity and integrity of the crystal.

[0032] Specifically, the chiral diphenylethylenediamine is (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine. As an optically pure chiral ligand, it has a clear intrinsic non-centrosymmetry (no inversion center), which is the core key to achieving chiral induction and breaking the centrosymmetric structure of the crystal. It can directionally regulate the molecular stacking mode through chiral induction, ensuring that the crystal has stable second-order nonlinear effects and birefringence properties.

[0033] Specifically, the structural formula of (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine is: .

[0034] The reaction process equation is as follows: .

[0035] According to the embodiments of the present invention, the (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine is 99% analytical grade (Shanghai Haohong Biomedical Technology Co., Ltd.).

[0036] According to an embodiment of the present invention, the zinc chloride is 99% analytical grade (Shanghai Maclean Biochemical Technology Co., Ltd.).

[0037] Example 2: (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine and zinc perchlorate hexahydrate were ground in a mortar at a stoichiometric ratio of 1:1 for 1 h to obtain a uniform white powder. 0.065 g of the powder was dissolved in 4 mL of methanol and stirred for 20 min, followed by the addition of 6 mL of dichloromethane and stirring for 10 min. After the reaction, the mixture was filtered into a 25 mL beaker, sealed with plastic wrap, punctured, and allowed to stand naturally for 5–6 days to evaporate, yielding transparent rectangular or irregular flaky crystals Z2. The chemical reaction formula is as follows: .

[0038] Example 3: (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine and zinc nitrate hexahydrate were ground in a mortar at a stoichiometric ratio of 1:1 for 1 h to obtain a uniformly mixed white powder. 0.055 g of the powder was placed in a 25 mL beaker, along with 2 mL of methanol and 2 mL of acetone. After stirring for 10 min until completely dissolved, 8 mL of the poor solvent dichloromethane was added and stirred for another 10 min. The mixture was then filtered into a new beaker, sealed with plastic wrap, punctured, and allowed to stand naturally for 5–6 days to evaporate, yielding transparent rectangular or irregularly shaped flaky crystals Z3. The chemical reaction is as follows: .

[0039] Crystal performance testing methods: (1) X-ray single crystal diffraction test: The Smart-Apex-II X-ray single crystal diffractometer of Bruker, Germany was used. The radiation source was a molybdenum target, Mo-Kα rays (λ=0.71073 A), the data collection current was 30 mA, the voltage was 50 KV, and the temperature was 293 K. The crystal structure was analyzed by a dual method using ShelXT 2018 software, and the least squares method F2 was used for refinement. The data was restored and the absorption correction was completed by SAINT software.

[0040] (2) X-ray powder diffraction test: A SmartLab SE X-ray powder diffractometer from Rigaku Corporation of Japan was used, with a Cu target, Ka spectral line, Ni filter, voltage of 40 kV, current of 20 mA, and scanning speed of 0.02 ° / min. The theoretical XRD value was calculated using VESTA software.

[0041] (3) Infrared spectroscopy test: A PerkinElmer Frontier Fourier transform infrared spectrometer was used, with a test range of 4000~500 cm⁻¹. -1 .

[0042] (4) Ultraviolet-visible-near-infrared spectroscopy test: The Shimadzu UV-2700 spectrometer was used for the test based on the diffuse reflectance method.

[0043] (5) Thermal stability test: Thermogravimetric-differential scanning calorimetry (TG-DSC) was performed using a NETZSCH STA 449F3 simultaneous thermal analyzer from Germany in a nitrogen atmosphere. The temperature range was 30~600 ℃ and the heating rate was 10 ℃ / min.

[0044] (6) Second harmonic effect test: Referring to the Kurtz-Perry powder technology, an Nd:YAG solid-state laser (1064nm fundamental frequency light) was used to test the SHG response in the particle size range of 50~300 μm, with particle size ranges of 0~100 μm, 100~150 μm, 150~200 μm, 200~250 μm and 250~300 μm.

[0045] (7) Birefringence test: The birefringence of the sample crystal was accurately measured using a Zeiss Axio Scope A1 polarizing microscope equipped with a Berek compensator.

[0046] Test results: The X-ray single-crystal diffraction test results of Example 1 are shown in Figure 2. The crystal structure of the sample is as follows: It belongs to the orthorhombic crystal system, and its space group is The unit cell parameters are , , , , , , , F(000) = 888.0. Figure 1 An optical photograph of the chiral zinc complex crystal prepared in Example 1.

[0047] The X-ray powder diffraction test results of Example 1 are shown in Figure 3. The peak positions of the XRD pattern of the sample crystal are the same as those of the theoretical peaks. The signal baseline is stable and the diffraction characteristic peaks are obvious, indicating that the synthesized organic ionic crystal has high purity, which proves the correctness of the crystal structure obtained by single crystal diffraction analysis.

[0048] The infrared spectral test results of Example 1 are shown in Figure 4, 3062 The absorption peak at 1648 originates from the stretching vibration of unsaturated CH in the ligand; The strong absorption at this point is a characteristic stretching vibration of C=N, confirming that ethylamine and acetone underwent a condensation reaction to form an imine structure. The disappearance of the characteristic peaks of the functional groups proves that the two have not completely condensed into bis-Schiff base ligands; 1450 The absorption peak at 1378 corresponds to the aromatic vibration on the benzene ring. The characteristic absorption peak for the deformation vibration of methyl groups is at 1253. The peak at 1031 is the characteristic absorption peak for the stretching vibration of the CN single bond. The nearby characteristic peak is the absorption peak of the in-plane bending vibration of the CH group of the benzene ring, 715. The characteristic peaks that appear nearby are absorption peaks of the out-of-plane bending vibration of the CH group of the benzene ring.

[0049] The UV-Vis-NIR absorption spectroscopy results of Example 1 are shown in Figure 5. The sample crystal exhibits significant absorption characteristics in the UV region (200–340 nm), with a maximum cutoff wavelength of 242 nm. In the visible to near-infrared region, it exhibits extremely high transmittance, with the transmittance exceeding 90% in the 300–800 nm range. The optical bandgap value of the sample crystal, calculated using the Tauc method, is 4.49 eV, as shown in Figure 6. These data demonstrate the crystal's strong absorption in the UV region and high transmittance in the visible-near-infrared region, proving its excellent broad spectral response characteristics and significant application potential in optoelectronics and terahertz optical devices.

[0050] The TG-DSC test results of Example 1 are shown in Figure 7. The crystal decomposition temperature was 290 °C. The crystal mass showed a continuous decrease from about 290 °C, and the residual mass of the sample was 24.2% at 600 °C. These data indicate that the decomposition temperature of the sample crystal is at a relatively high level, and it has good thermal stability.

[0051] The test results of the second harmonic effect in Example 1 are as follows: Figures 8 to 9 As shown, the sample crystals are in the range of 200–250 °C. Within the particle size range, the SHG signal intensity is 0.49 times that of KDP, confirming the feasibility of this material as a potential second-order nonlinear optical material. Furthermore, the SHG signal increases with increasing particle size, satisfying the Kurtz-Perry phase matching condition, and the fundamental and harmonic light can effectively accumulate macroscopic polarization within the coherence length.

[0052] Example 1 shows the wavelength-dependent refractive index and birefringence of the sample crystal along each crystal axis using DFT simulation, as shown in Figure 10. Figure 12 The actual measured birefringence of the sample crystal is 0.047@1064 nm. Figure 10 The calculation results show that the birefringence of the sample crystal is 0.037@1064 nm. The birefringence obtained by experiments and calculations (0.047 and 0.037) are both moderate and have suitable birefringence characteristics, which makes it a potential nonlinear optical crystal in the ultraviolet or visible light band. Through an effective frequency conversion process, it can be applied to the field of laser technology.

[0053] In addition to the tests performed on Example 1, partial tests were also conducted on Examples 2 and 3. A series of performance characterizations were performed on the zinc complex, and the optical performance and thermal stability of the crystal device were tested. The performance characterization results show that: , All exhibit a wide transmittance range (300–800 nm and 350–800 nm), high near-infrared transmittance (>90%), optical band gap values ​​(4.48 eV and 4.46 eV), good thermal stability (decomposition temperatures of 271.2℃ and 255℃, respectively), and second harmonic generation effect (0.75×KDP and 0.60×KDP, respectively), with the harmonic intensity being related to the crystal size.

[0054] Based on the above, this application selects (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine as the chiral ligand, making full use of its intrinsic non-centrosymmetry (no inversion center) core characteristic, combined with of The advantages of the electronic configuration (no dd absorption and excellent optical transparency) are achieved by breaking the crystal's central symmetry through chiral induction, ensuring that the crystal simultaneously possesses second-order nonlinear effects and birefringence properties, thus realizing the synergistic optimization of the two optical properties.

[0055] The chiral zinc complex crystal prepared in this application has the following chemical formula: It belongs to the orthorhombic crystal system. The space group possesses specific cell parameters and excellent optical and thermal stability, as well as well-defined second-order nonlinearity and birefringence.

[0056] Induction is achieved through chiral small molecules with intrinsic noncentrosymmetry, and combined with... of The advantageous electronic configuration enables the crystal to form a non-centrosymmetric orthorhombic crystal system, ensuring stable second-order nonlinear effects (0.49×KDP) and achieving a suitable birefringence (0.047@1064 nm), meeting the core requirements of laser frequency conversion and phase matching. This achieves synergistic optimization of the frequency doubling coefficient and birefringence: the crystal simultaneously possesses significant second-harmonic effects and a suitable birefringence (0.047@1064 nm), resulting in more comprehensive optical performance and a wider range of applications.

[0057] This application employs a simple solvent evaporation method, which eliminates the need for complex equipment and high-temperature, high-pressure conditions. It enables the large-scale, high-purity preparation of crystals and allows for the stable production of chiral zinc complex crystals that possess both second-order nonlinear properties and birefringence, thereby reducing the difficulty of industrial production.

[0058] The chiral zinc complex crystals described in this application can be used in optical fields such as ultraviolet-visible laser frequency doubling output, optical parametric amplifiers, and laser frequency converters. Their core advantages mainly stem from the chiral ligands and... The synergistic effect endows the non-centrosymmetric structure, second-order nonlinearity, and birefringence properties with the ability to meet the application requirements of multiple fields.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chiral zinc complex crystal possessing both second-order nonlinearity and birefringence, characterized in that, The molecular formula is The chiral zinc complex crystal belongs to the orthorhombic crystal system, with space group [missing information]. It is a non-centrosymmetric structure; it possesses second-order nonlinear effects and birefringence properties.

2. A method for preparing chiral zinc complex crystals, characterized in that, Used to prepare chiral zinc complex crystals as described in claim 1; through intrinsically non-centrosymmetric chiral ligands, with d 10 Zn without dd electron transition absorption 2+ Through synergistic effects, the arrangement of molecules in crystals or thin films can be effectively controlled by chiral induction, breaking the centrosymmetry of crystals, widening the optical transmission window of crystals, and directionally preparing chiral zinc complex crystals that simultaneously possess second-order nonlinear effects and suitable birefringence properties.

3. The method for preparing chiral zinc complex crystals according to claim 2, characterized in that, Specifically, the following steps are included: (1) Mix the chiral ligand and zinc salt, grind them thoroughly in a mortar until they are evenly mixed, and obtain a white powder; (2) Add a polar organic solvent to step one and stir until it is completely dissolved to provide a homogeneous reaction system for the coordination reaction; (3) Continue to add non-polar solvent to step two and stir the reaction for the preset time, then filter into a beaker; (4) Seal the opening with plastic wrap, punch holes and let it stand for 3 to 6 days to allow natural evaporation and crystal growth to obtain chiral zinc complex crystals.

4. The method for preparing chiral zinc complex crystals according to claim 3, characterized in that: The chiral ligand is chiral diphenylethylenediamine; the zinc salt has... electronic configuration The chiral diphenylethylenediamine is (1R,2R)-(+)-1,2-diphenyl-1,2-ethylenediamine; its structural formula is: 。 5. The method for preparing chiral zinc complex crystals according to claim 4, characterized in that, The zinc salt is one or a combination of zinc chloride, zinc perchlorate hexahydrate, and zinc nitrate hexahydrate.

6. The method for preparing chiral zinc complex crystals according to claim 3, characterized in that: The polar organic solvent is acetone; The nonpolar solvent is n-hexane.

7. The method for preparing chiral zinc complex crystals according to claim 3, characterized in that: The polar organic solvent is methanol; The nonpolar solvent is dichloromethane.

8. The method for preparing chiral zinc complex crystals according to claim 3, characterized in that: The polar organic solvent is methanol; The nonpolar solvent is acetone.

9. The method for preparing chiral zinc complex crystals according to claim 3, characterized in that: The grinding time in the mortar should be at least 1 hour; Add a polar organic solvent and stir for at least 10 minutes; Add a non-polar solvent and stir for at least 10 minutes.

10. An application of a chiral zinc complex crystal with both second-order nonlinearity and birefringence in the field of nonlinear optics.

Images