Chiral crystal as well as preparation method and application thereof
By preparing the chiral crystal C5H14N2I4, the problems of high processing difficulty and insufficient performance of existing crystal materials have been solved, and high-performance birefringence and nonlinear optical effects have been achieved, which are suitable for the preparation of polarization devices and nonlinear optical devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
- Filing Date
- 2024-10-17
- Publication Date
- 2026-04-17
Smart Images
Figure CN121874933A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of nonlinear optical crystal applications and laser technology. More specifically, it relates to a chiral crystal, its preparation method, and its applications. Background Technology
[0002] Birefringent crystals are a class of natural or synthetic crystalline materials with unique optical properties, playing a crucial role not only in basic scientific research but also in numerous practical applications. They are widely used in optical instruments, laser technology, optical communication, display technology, and biomedical imaging. For example, by precisely controlling the birefringence effect, important optical components such as polarizers, waveplates, and laser Q-switching elements can be manufactured. Currently, commercially available birefringent crystals include TiO2, CaCO3, α-BaB2O4, MgF2, LiNbO3, and YVO4. However, these birefringent materials all have some drawbacks. For example, TiO2 mainly exists in natural form, making artificial synthesis difficult, and its small size and high hardness hinder processing; MgF2 has too low a birefringence, which is unfavorable for the manufacture of Glan prisms; YVO4 has a complex growth method, which is not conducive to obtaining high-quality crystals, and its ultraviolet transmittance is weak. In view of this, exploring new and excellent birefringent crystals has become a potential research direction in the field of optical materials.
[0003] Nonlinear optical crystals, through frequency conversion, can cover a broad spectral range of laser output from deep ultraviolet to mid-infrared, making them crucial components of all-solid-state laser technology. Due to their high conversion efficiency and good beam quality, nonlinear optical crystals are widely used in precision manufacturing, bioimaging, communications, and spectroscopy. In particular, mid-infrared lasers covering the 3-5 μm and 8-12 μm atmospheric windows play a vital role in many military and civilian applications, including remote sensing, biological tissue visualization, and communications. Currently, the mainstream mid-infrared nonlinear optical crystals on the market are AgGaS2, AgGaSe2, and ZnGeP2. However, these materials also have internal limitations, such as the low laser damage threshold of AgGaS2 and AgGaSe2, and the heavy two-photon absorption of ZnGeP2 in ~1 μm laser pumping, which cannot fully meet the high-performance standards of developing mid-infrared laser technology. Therefore, exploring promising mid-infrared nonlinear optical crystal materials has become a cutting-edge research hotspot in the field of nonlinear materials. Summary of the Invention
[0004] Based on the above facts, the purpose of this invention is to provide a chiral crystal, its preparation method, and its applications. This chiral crystal possesses both excellent birefringence and superior nonlinear optical effects, and can be used to fabricate polarization devices and nonlinear optical devices.
[0005] To achieve the above objectives, the present invention adopts the following technical solution:
[0006] On one hand, the present invention provides a chiral crystal with the molecular formula C5H. 14 N2I4 belongs to the monoclinic crystal system and has the space group P21.
[0007] The unit cell parameters of the chiral crystal are: α=90°, β=94.75°, γ=90°, Z = 2; or
[0008] The cell parameters of the chiral crystal are as follows: α=90°, β=94.95°, γ=90°, Z = 2.
[0009] In this invention, the chiral crystal has an R-type or S-type configuration. When the chiral crystal has an R-type configuration, the cell parameters of the chiral crystal are: α=90°, β=94.75°, γ=90°, Z = 2; when the chiral crystal has an S-type configuration, the cell parameters of the chiral crystal are: b = 7.60 α=90°, β=94.95°, γ=90°, Z = 2.
[0010] Further, the chemical formula of the crystal is (R)-(MPz)I2(I2) or (S)-(MPz)I2(I2), wherein R-MPz is (R)-(-)-2-methylpiperazinyl cation, and S-MPz is (S)-(+)-2-methylpiperazinyl cation, both with the chemical formula (C5H 14 N2)2+.
[0012] Furthermore, the structural formula of the (R)-(-)-2-methylpiperazinyl cation is as follows:
[0013] Furthermore, the structural formula of the (S)-(+)-2-methylpiperazinyl cation is as follows:
[0014] In the technical solution of this invention, when the chemical formula of the crystal is (R)-(MPz)I2(I2), the corresponding unit cell parameters are: α=90°, β=94.75°, γ=90°, Z = 2.
[0015] When the chemical formula of the crystal is (S)-(MPz)I2(I2), the corresponding unit cell parameters are: α=90°, β=94.95°, γ=90°, Z = 2.
[0016] In another aspect, the present invention provides a method for preparing chiral crystals as described above, comprising the following steps:
[0017] Dissolve (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine in a solution containing hydroiodic acid, stir until a clear brown solution is obtained, and then allow it to cool naturally. The precipitate is the chiral crystal.
[0018] Furthermore, the stirring temperature is between room temperature and 100°C. It can be understood that "room temperature" here refers to 25-30°C.
[0019] Furthermore, the stirring temperature includes, but is not limited to, 40–90°C, 40–60°C, 60–90°C, 40°C, 60°C, and 90°C.
[0020] Furthermore, the process of naturally cooling and precipitating chiral crystals involves allowing the brown, clear solution to stand at room temperature to crystallize, then filtering it with filter paper to obtain the chiral crystals.
[0021] Further, the molar ratio of (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine to hydroiodic acid is 1:(3-100).
[0022] Preferably, the molar ratio of (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine to hydroiodic acid is 1:(14-100), 1:(14-43), 1:(14-29), 1:(29-100), 1:(29-43), 1:(43-100), 1:14, 1:29, 1:43, 1:100, etc.
[0023] Furthermore, the solvent of the hydroiodic acid-containing solution is one or more of water, ethanol, and methanol.
[0024] Furthermore, in the solution containing hydroiodic acid, the mass fraction of hydroiodic acid is 45% to 50%.
[0025] Furthermore, the hydroiodic acid-containing solution contains less than 1.5 wt% H3PO2.
[0026] In another aspect, the present invention provides a method for preparing chiral crystals as described above, comprising the following steps:
[0027] Mix (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine with hydroiodic acid and place it in the lining of a hydrothermal reactor. Seal the reactor and heat it to 50-120°C. Hold the temperature for 6-48 hours and then cool it to room temperature. Remove the sample to obtain the chiral crystal.
[0028] Furthermore, the temperature after heating is preferably 110°C, and the constant temperature time is 48 hours.
[0029] Furthermore, the time for cooling to room temperature is 60–72 hours, preferably 72 hours.
[0030] Further, the molar ratio of (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine to hydroiodic acid is 1:(3-100).
[0031] In another aspect, the present invention provides the application of chiral crystals as described above in the fabrication of polarization devices or nonlinear optical devices.
[0032] In another aspect, the present invention provides a polarization device, which is prepared from a chiral crystal as described above.
[0033] In another aspect, the present invention provides a nonlinear optical device, which is prepared from a chiral crystal as described above.
[0034] Furthermore, the nonlinear optical device includes, but is not limited to, frequency doubling devices, electro-optic devices, harmonic generators, or optical parametric devices selected from the infrared band.
[0035] The beneficial effects of this invention are as follows:
[0036] The chiral crystal C5H provided in this invention 14 The N2I4 crystal growth method is simple and low-cost. It has great birefringence properties and also exhibits excellent nonlinear optical effects, making it suitable for fabricating polarization devices and nonlinear optical devices. Attached Figure Description
[0037] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
[0038] Figure 1 Chiral crystal C5H is shown 14 Crystal images of N2I4, where (a) is a crystal image of (R)-(MPz)I2(I2) and (b) is a crystal image of (S)-(MPz)I2(I2).
[0039] Figure 2 Chiral crystal C5H is shown 14Theoretical and experimental XRD patterns of N2I4, where (a) is the theoretical and experimental XRD pattern of (R)-(MPz)I2(I2) and (b) is the theoretical and experimental XRD pattern of (S)-(MPz)I2(I2).
[0040] Figure 3 Chiral crystal C5H is shown 14 Schematic diagrams of the crystal structure of N2I4, where (a) is the crystal structure diagram of (R)-(MPz)I2(I2) and (b) is the crystal structure diagram of (S)-(MPz)I2(I2).
[0041] Figure 4 The theoretically calculated chiral crystal C5H is shown. 14 The refractive index and birefringence of N2I4 at different wavelengths are shown, where (a) is the theoretical calculated value of (R)-(MPz)I2(I2) and (b) is the theoretical calculated value of (S)-(MPz)I2(I2).
[0042] Figure 5 The theoretically calculated chiral crystal C5H is shown. 14 The SHG intensity of N2I4 in the direction, where (a) is the theoretical calculated value of (R)-(MPz)I2(I2) and (b) is the theoretical calculated value of (S)-(MPz)I2(I2). Detailed Implementation
[0043] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.
[0044] Chiral crystal C5H 14 Preparation method of N2I4:
[0045] Example 1
[0046] Chiral crystal C5H 14 The method for preparing N2I4 includes the following steps:
[0047] Weigh 0.1 g of (R)-(-)-2-methylpiperazine and place it in a beaker. Then add 4 mL of HI aqueous solution to the beaker, wherein the molar ratio of (R)-(-)-2-methylpiperazine to HI is 1:29, and the mass fraction of HI in the HI aqueous solution is 45% to 50%, containing ≤1.5% H3PO2. Heat to 60°C and stir to obtain a clear brown solution.
[0048] Then, the obtained solution was allowed to stand at room temperature to crystallize, and the crystals were separated by filtration with filter paper to obtain the chiral crystal C5H. 14 N2I4, the chemical formula of this chiral crystal is (R)-(MPz)I2(I2), and its crystal photograph is shown below. Figure 1 As shown in Figure a.
[0049] Example 2
[0050] Chiral crystal C5H 14 The method for preparing N2I4 includes the following steps:
[0051] Weigh 0.1 g of (S)-(+)-2-methylpiperazine into a beaker, then add 6 mL of HI aqueous solution and 1 mL of methanol to the beaker. The molar ratio of (S)-(-)-2-methylpiperazine to HI is 1:43, and the HI aqueous solution contains 45%–50% HI by mass and ≤1.5% H3PO2. Heat to 90°C and stir to obtain a clear brown solution.
[0052] Then, the obtained solution was allowed to stand at room temperature to crystallize, and the crystals were separated by filtration with filter paper to obtain the chiral crystal C5H. 14 N2I4, the chemical formula of this chiral crystal is (S)-(MPz)I2(I2), and its crystal photograph is shown below. Figure 1 As shown in b.
[0053] Example 3
[0054] Chiral crystal C5H 14 The method for preparing N2I4 includes the following steps:
[0055] Weigh 0.1 g of (S)-(+)-2-methylpiperazine and place it in a beaker. Then add 2 mL of HI aqueous solution and 0.5 mL of ethanol to a glass bottle. The molar ratio of (S)-(-)-2-methylpiperazine to HI is 1:14. The HI aqueous solution contains 45% to 50% HI by mass and ≤1.5% H3PO2. Heat to 40°C and stir to obtain a clear brown solution.
[0056] Then, the obtained solution was allowed to stand at room temperature to crystallize, and the crystals were separated by filtration with filter paper to obtain the chiral crystal C5H. 14 N2I4, the chemical formula of this chiral crystal is (S)-(MPz)I2(I2).
[0057] Example 4
[0058] Chiral crystal C5H 14 The method for preparing N2I4 includes the following steps:
[0059] Weigh 0.1 g of (R)-(-)-2-methylpiperazine and place it in a beaker. Then add 14 mL of HI aqueous solution to the beaker. The molar ratio of (R)-(-)-2-methylpiperazine to HI is 1:100. The HI aqueous solution contains 45% to 50% HI by mass and ≤1.5% H3PO2. Heat to 90°C and stir to obtain a clear brown solution.
[0060] Then, the obtained solution was allowed to stand at room temperature to crystallize, and the crystals were separated by filtration with filter paper to obtain the chiral crystal C5H. 14 N2I4, the chemical formula of this chiral crystal is (R)-(MPz)I2(I2).
[0061] Example 5
[0062] Chiral crystal C5H 14 The method for preparing N2I4 includes the following steps:
[0063] Weigh 0.1 g of (R)-(-)-2-methylpiperazine and place it in the lining of a hydrothermal reactor. Then add 4 mL of HI aqueous solution, fill the reactor, seal it, and place it in an oven. Heat the mixture to 110°C for 120 min and maintain the temperature for 48 h. After 72 h, cool the mixture to 30°C, remove the sample, and dry it to obtain the chiral crystal C5H. 14 N2I4, the chemical formula of this chiral crystal is (R)-(MPz)I2(I2).
[0064] In the above embodiments, the theoretical and experimental XRD patterns of the chiral crystal with the chemical formula (R)-(MPz)I2(I2) prepared are shown in the figure. Figure 2 As shown in Figure a; in the above embodiments, the theoretical and experimental XRD patterns of the chiral crystal with the chemical formula (S)-(MPz)I2(I2) prepared are shown in Figure a. Figure 2 As shown in b. The results show that the powder X-ray diffraction pattern obtained in the experiment is consistent with its corresponding theoretical XRD pattern.
[0065] The crystal structure diagram of the chiral crystal with the chemical formula (R)-(MPz)I2(I2) prepared in the above embodiments is shown in the figure below. Figure 3 As shown in Figure a; the schematic diagram of the crystal structure of the prepared chiral crystal with the chemical formula (S)-(MPz)I2(I2) is shown in Figure a. Figure 3 As shown in b. From Figure 3 From this, we can know that chiral crystals C5H 14 The crystal structure of N2I4 consists of organic cations (C5H4O3, C ... 14 N2) 2+It is composed of ((R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine), iodide anions, and iodine molecules. Iodide anions are present at the head and tail of the iodine molecule, forming a one-dimensional iodine chain. Organic cations are intercalated between the chains, alternately forming a three-dimensional "intercalation" structure.
[0066] C5H was analyzed using the commercial first-principles calculation software CASTEP. 14 The birefringence of the N2I4 crystal was evaluated, and the calculation results are as follows: Figure 4 As shown. Among them, Figure 4 In this context, 'a' is the theoretically calculated value of (R)-(MPz)I2(I2). Figure 4 (where b is the theoretically calculated value of (S)-(MPz)I2(I2), it can be seen that its C5H 14 The birefringence of N2I4 crystal reaches 1.26 or higher near 1064 nm.
[0067] First-principles calculations were performed on C5H 14 The nonlinear optical properties of N2I4 crystal were evaluated, and the calculation results are as follows: Figure 5 As shown (where Figure 5 In the equation (where a is the theoretical calculated value of (R)-(MPz)I2(I2) and b is the theoretical calculated value of (S)-(MPz)I2(I2), it can be seen that its C5H 14 The second harmonic generation (SHG) effect of N2I4 crystal in d 112 It reaches its maximum value in the direction, and the frequency doubling effect is comparable to that of commercial AgGaS2 crystals.
[0068] The (R)-(MPz)I₂(I₂) or (S)-(MPz)I₂(I₂) crystals prepared in Examples 1-5 were characterized by X-ray single-crystal diffraction. The instrument used was a Bruker D8 Quest single-crystal diffractometer (Bruker GmbH, Germany), with a Mo target as the X-ray emission source. Diffraction data were collected in the range of angles from 5.782° (5.71°) to 50.05° (55.99°). The diffraction data were subjected to absorption correction using the XPREP program, and then the structure was analyzed and the data were refined using OLEX2 software. The crystallographic data of the obtained (R)-(MPz)I2(I2) and (S)-(MPz)I2(I2) crystals are shown in Table 1.
[0069] Table 1
[0070]
[0071]
[0072] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.
Claims
1. A chiral crystal, characterized in that, The molecular formula of the chiral crystal is C5H. 14 N2I4 belongs to the monoclinic crystal system and has the space group P21. The unit cell parameters of the chiral crystal are: α=90°, β=94.75°, γ=90°, Z = 2; or The cell parameters of the chiral crystal are as follows: α=90°, β=94.95°, γ=90°, Z = 2.
2. The chiral crystal according to claim 1, characterized in that, The crystal has the chemical formula (R)-(MPz)I2(I2) or (S)-(MPz)I2(I2), where R-MPz is (R)-(-)-2-methylpiperazinyl cation and S-MPz is (S)-(+)-2-methylpiperazinyl cation, both with the chemical formula (C5H). 14 N2) 2+ .
3. The method for preparing a chiral crystal as described in claim 1 or 2, characterized in that, Includes the following steps: Dissolve (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine in a solution containing hydroiodic acid, stir until a clear brown solution is obtained, and then allow it to cool naturally. The precipitate is the chiral crystal.
4. The preparation method according to claim 3, characterized in that, The stirring temperature is between room temperature and 100°C.
5. The preparation method according to claim 3, characterized in that, The molar ratio of (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine to hydroiodic acid is 1:(3-100).
6. The preparation method according to claim 3, characterized in that, The solvent for the hydroiodic acid solution is one or more of water, ethanol, and methanol.
7. The method for preparing a chiral crystal as described in claim 1 or 2, characterized in that, Includes the following steps: Mix (R)-(-)-2-methylpiperazine or (S)-(+)-2-methylpiperazine with hydroiodic acid and place it in the lining of a hydrothermal reactor. Seal the reactor and heat it to 50-120°C. Hold the temperature for 6-48 hours and then cool it to room temperature. Remove the sample to obtain the chiral crystal.
8. The application of the chiral crystal as described in claim 1 or 2 in the fabrication of polarization devices or nonlinear optical devices.
9. A polarization device, characterized in that, It is prepared from the chiral crystal as described in claim 1 or 2.
10. A nonlinear optical device, characterized in that, It is prepared from the chiral crystal as described in claim 1 or 2.