Chiral zinc-based metal halide single crystal material and preparation method and application thereof

Abstract

The present invention discloses a chiral zinc-based metal halide single crystal material, its preparation method and applications, belonging to the field of nonlinear optical crystals. The single crystal material of the present invention is a nonlinear optical crystal, belonging to the orthorhombic system, with the characteristics of being lead-free, low-toxic, wide bandgap and high stability, having second harmonic response, and showing broad application prospects as a nonlinear optical crystal. The preparation method of the present invention constructs crystal materials (3CLTPP)2ZnBr4 and (5CLTPP)2ZnBr4 crystallized in chiral space groups with achiral building blocks cyclopropyltriphenylphosphonium cation or cyclopentyltriphenylphosphonium cation, breaking the traditional mode of constructing chiral crystal materials with chiral templates, and providing a new guiding idea for the design of chiral organic-inorganic hybrid metal halide crystals. The preparation method is simple to operate, the reaction is mild, and it is easy to promote.

Description

Technical Field

[0001] The invention belongs to the technical field of nonlinear optical crystals, and in particular relates to a chiral zinc-based metal halide single crystal material and a preparation method and application thereof. Background Art

[0002] Organic-inorganic hybrid metal halides are a new type of material with rich chemical structures and compositions. They have received extensive attention in the field of nonlinear optical crystal materials. However, nonlinear optical crystal materials must meet strict symmetry requirements to be realized, so the preparation of such materials is a considerable challenge. The existing technology generally uses chiral organic templates to construct chiral organic-inorganic hybrid metal halide crystals. However, chiral organic templates are limited and expensive, which severely restricts the preparation of chiral organic-inorganic hybrid metal halides and their application in the field of nonlinear optics. Therefore, it is necessary to conduct in-depth research on the construction of chiral organic-inorganic hybrid metal halide single crystals with non-chiral templates, so as to open up new ideas for the design and synthesis of new organic-inorganic hybrid metal halide crystals. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a chiral zinc-based metal halide single crystal material having the advantages of lead-free, low toxicity, wide band gap, high stability and nonlinear optical properties, as well as a preparation method and application thereof.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A chiral zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (3CLTPP) 2 ZnBr 4 or (5CLTPP) 2 ZnBr 4 , wherein 3CLTPP is a cyclopropyltriphenylphosphonium cation, 5CLTPP is a cyclopentyltriphenylphosphonium cation, and the single crystal material is a nonlinear optical crystal belonging to the orthorhombic system;

[0006] (3CLTPP) 2 ZnBr 4 The chemical structure is:

[0007]

[0008] (5CLTPP) 2 ZnBr 4 The chemical structure is:

[0009] .

[0010] The chiral zinc-based metal halide single crystal material is preferably (3CLTPP) 2 ZnBr 4 The tetrahedral unit in the crystal structure [ZnBr 4 ] is separated by the cation 3CLTPP to form a zero-dimensional structure, and the space group is a chiral space group P 2 1 2 1 2 1 ; (5CLTPP) 2 ZnBr 4 The tetrahedral unit in the crystal structure [ZnBr 4 ] is separated by the cation 5CLTPP to form a zero-dimensional structure, and the space group is a chiral space group P 2 1 2 1 2 1 .

[0011] The chiral zinc-based metal halide single crystal material is preferably (3CLTPP) 2 ZnBr 4 The unit cell parameters are a=14.836(3) Å, b=16.240(3) Å, c=17.199(3) Å, α=β=γ=90 o ; (5CLTPP) 2 ZnBr 4 The unit cell parameters are a=15.087(3) Å, b=16.777(3) Å, c=17.377(3) Å, α=β=γ=90 o .

[0012] The chiral zinc-based metal halide single crystal material mentioned above, preferably, the nonlinear optical crystal is a colorless transparent crystal, (3CLTPP) 2 ZnBr 4 The powder frequency doubling performance of the crystal is 0.18×KH 2 PO 4 , (5CLTPP) 2 ZnBr 4 The powder frequency doubling performance of the crystal is 0.10×KH 2 PO 4 .

[0013] As a general technical concept, the present invention also provides a method for preparing the above-mentioned chiral zinc-based metal halide single crystal material, comprising the following steps:

[0014] (1) Dissolve the phenylphosphonium cation reagent and zinc bromide in methanol solution in an open container and stir thoroughly at room temperature to form a clear and transparent precursor solution;

[0015] (2) Place the open container containing the precursor solution in a covered container containing ether at room temperature, cover it with a lid and seal it. Allow it to stand until the ether diffuses into the precursor solution to form colorless block crystals.

[0016] (3) washing the colorless block crystals with ether and drying under reduced pressure to obtain a chiral zinc-based metal halide single crystal material;

[0017] When the phenylphosphonium cation reagent is cyclopropyltriphenylphosphonium bromide, the chemical formula of the chiral zinc-based metal halide single crystal material is (3CLTPP) 2 ZnBr 4 ;

[0018] When the phenylphosphonium cation reagent is cyclopentyltriphenylphosphonium bromide, the chemical formula of the chiral zinc-based metal halide single crystal material is (5CLTPP) 2 ZnBr 4 .

[0019] In the above-mentioned method for preparing the chiral zinc-based metal halide single crystal material, preferably, in step (1) and step (2), the molar mass volume ratio of the phenylphosphonium cation reagent, zinc bromide, methanol and diethyl ether is 0.2 mmol to 0.3 mmol: 0.1 mmol to 0.15 mmol: 2 mL to 3 mL: 20 mL to 25 mL.

[0020] In the above-mentioned method for preparing the chiral zinc-based metal halide single crystal material, preferably, in step (1), the stirring speed is 200 r / min to 300 r / min, and the stirring time is 5 min to 10 min.

[0021] In the above method for preparing the chiral zinc-based metal halide single crystal material, preferably, in step (2), the diffusion time is 36 h to 48 h.

[0022] In the above-mentioned method for preparing the chiral zinc-based metal halide single crystal material, preferably, in step (3), the reduced pressure drying is specifically: drying for at least 10 min at a temperature of 50°C to 60°C under a vacuum pressure of 100 Pa to 120 Pa.

[0023] As a general technical concept, the present invention also provides an application of the chiral zinc-based metal halide single crystal material or the chiral zinc-based metal halide single crystal material prepared by the above preparation method in the field of nonlinear optics.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] (1) The chiral zinc-based metal halide single crystal material of the present invention has the chemical formula (3CLTPP)2 ZnBr 4 or (5CLTPP) 2 ZnBr 4 , wherein 3CLTPP is a cyclopropyltriphenylphosphonium cation, and 5CLTPP is a cyclopentyltriphenylphosphonium cation. The present invention adopts specific non-chiral primitive cyclopropyltriphenylphosphonium cation and cyclopentyltriphenylphosphonium cation to obtain a chiral zinc-based metal halide single crystal material, that is, a chiral zinc-based organic-inorganic hybrid metal halide crystal material. The single crystal material is a nonlinear optical crystal, belongs to the orthorhombic system, has the advantages of lead-free, low toxicity, wide band gap and high stability, and also has a second harmonic response (0.18×KH 2 PO 4 and 0.10×KH 2 PO 4 ), has good nonlinear optical properties.

[0026] (2) The preparation method of the chiral zinc-based metal halide single crystal material of the present invention breaks the inherent limitation of using chiral templates to construct chiral organic-inorganic hybrid metal halide single crystal materials. It cleverly uses non-chiral primitives cyclopropyltriphenylphosphonium bromide, cyclopentyltriphenylphosphonium bromide and zinc bromide as raw materials, methanol as a good solvent, and ether as an anti-solvent to synthesize chiral zinc-based organic-inorganic hybrid metal halide crystal compounds (3CLTPP) by an anti-solvent method at room temperature. 2 ZnBr 4 or (5CLTPP) 2 ZnBr 4 The preparation method is simple to operate, mild in reaction, and easy to scale up for production.

[0027] (3) The chiral zinc-based metal halide single crystal material of the present invention has the advantages of being lead-free, low-toxic, having a wide bandgap and high stability, and also has a second harmonic response, and has good application prospects in nonlinear optics. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the crystal structure of the chiral zinc-based metal halide single crystal material of Example 1 and Example 2 of the present invention, wherein (a) is (3CLTPP) 2 ZnBr 4 Schematic diagram of the crystal structure, (b) is (5CLTPP) 2 ZnBr 4 Schematic diagram of the crystal structure.

[0029] Figure 2 The XRD diagrams of the chiral zinc-based metal halide single crystal materials of Examples 1 and 2 of the present invention, wherein (a) is (3CLTPP) 2 ZnBr 4XRD pattern of crystal, (b) is (5CLTPP) 2 ZnBr 4 XRD pattern of the crystal.

[0030] Figure 3 The ultraviolet-visible absorption spectra of the chiral zinc-based metal halide single crystal materials of Examples 1 and 2 of the present invention are shown.

[0031] Figure 4 The chiral zinc-based metal halide single crystal material of Example 1 and Example 2 of the present invention and KH 2 PO 4 Comparison of the second harmonic signal strength. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby. The materials and instruments used in the following examples and comparative examples are all commercially available, and the room temperature referred to is 25°C to 30°C.

[0033] Example 1

[0034] A chiral zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (3CLTPP) 2 ZnBr 4 , wherein 3CLTPP is a cyclopropyltriphenylphosphonium cation, (3CLTPP) 2 ZnBr 4 The chemical structure is:

[0035]

[0036] The single crystal material of this embodiment is a nonlinear optical crystal, which is colorless and transparent, belongs to the orthorhombic system, and the space group is a chiral space group P 2 1 2 1 2 1 , the unit cell parameters are a=14.836(3) Å, b=16.240(3) Å, c=17.199(3) Å, α=β=γ=90 o ; Its powder frequency doubling performance is 0.18×KH 2 PO 4 .

[0037] A method for preparing the chiral zinc-based metal halide single crystal material of the present embodiment comprises the following steps:

[0038] (1) In a 5 mL open glass bottle, dissolve 76.65 mg (0.2 mmol) of cyclopropyltriphenylphosphonium bromide and 22.52 mg (0.1 mmol) of zinc bromide in 2 mL of methanol solution and stir thoroughly at room temperature until a clear and transparent precursor solution is formed;

[0039] (2) Place the glass bottle containing the precursor solution in a 50 mL covered glass bottle containing 20 mL of ether at room temperature, cover the bottle cap, and let it stand, waiting for the ether to diffuse into the precursor solution for 36 hours to form colorless block crystals;

[0040] (3) Wash the colorless block crystals with ether and dry under reduced pressure to obtain a product with the chemical formula (3CLTPP) 2 ZnBr 4 Chiral zinc-based metal halide single crystal materials.

[0041] In step (1), the stirring speed is 200 r / min and the stirring time is 5 min.

[0042] In step (3), the reduced pressure drying is specifically: drying at a temperature of 50° C. for 10 min under a vacuum pressure of 100 Pa.

[0043] Example 2

[0044] A chiral zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (5CLTPP) 2 ZnBr 4 , wherein 5CLTPP is a cyclopentyltriphenylphosphonium cation, (5CLTPP) 2 ZnBr 4 The chemical structure is:

[0045]

[0046] The single crystal material of this embodiment is a nonlinear optical crystal, which is colorless and transparent, belongs to the orthorhombic system, and the space group is a chiral space group P 2 1 2 1 2 1 , the unit cell parameters are a=15.087(3) Å, b=16.777(3) Å, c=17.377(3) Å, α=β=γ=90 o ; Its powder frequency doubling performance is 0.10×KH 2 PO 4 .

[0047] A method for preparing the chiral zinc-based metal halide single crystal material of the present embodiment comprises the following steps:

[0048] (1) In a 5 mL open glass bottle, dissolve 82.26 mg (0.2 mmol) of cyclopentyltriphenylphosphonium bromide and 22.52 mg (0.1 mmol) of zinc bromide in 2 mL of methanol solution and stir thoroughly at room temperature until a clear and transparent precursor solution is formed;

[0049] (2) Place the glass bottle containing the precursor solution in a 50 mL covered glass bottle containing 20 mL of ether at room temperature, cover the bottle cap, and let it stand, waiting for the ether to diffuse into the precursor solution for 36 hours to form colorless block crystals;

[0050] (3) Wash the colorless block crystals with ether and dry under reduced pressure to obtain a product with the chemical formula (5CLTPP) 2 ZnBr 4 Chiral zinc-based metal halide single crystal materials.

[0051] In step (1), the stirring speed is 200 r / min and the stirring time is 5 min.

[0052] In step (3), the reduced pressure drying is specifically: drying at a temperature of 50° C. for 10 min under a vacuum pressure of 100 Pa.

[0053] Performance Testing

[0054] (1) SCXRD test:

[0055] The single crystal diffraction data were measured at 298 K using a Bruker D8 Venture single crystal diffractometer (Mo Ka), and the data were reduced using the Bruker APEX3 program. Subsequently, the Olex2 program based on the SHELXTL software package was used for preliminary structural analysis, and the coordinates of all non-hydrogen atoms were determined by the difference Fourier method. All non-hydrogen atoms were then anisotropically refined using the least squares method based on F2, and the positions of hydrogen atoms were obtained by theoretical hydrogenation.

[0056] Yes (3CLTPP) 2 ZnBr 4 and (5CLTPP) 2 ZnBr 4 The crystal materials were tested by SCXRD and all belonged to the orthorhombic system and the space groups were all chiral space groups. P 2 1 2 1 2 1 , (3CLTPP) 2 ZnBr 4The unit cell parameters are a=14.836(3)Å, b=16.240(3)Å, c=17.199(3)Å, α=β=γ=90 o ; (5CLTPP) 2 ZnBr 4 The unit cell parameters are a=15.087(3)Å, b=16.777(3)Å, c=17.377(3)Å, α=β=γ=90 o The obtained crystal structure is shown in Figure 1 As shown, Figure 1 (a) in (3CLTPP) 2 ZnBr 4 Schematic diagram of the crystal structure of Figure 1 (b) in (5CLTPP) 2 ZnBr 4 Schematic diagram of the crystal structure of Figure 1 (a) in (3CLTPP) 2 ZnBr 4 The tetrahedral unit in the crystal structure [ZnBr 4 ] are separated by the cation 3CLTPP to form a zero-dimensional structure; Figure 1 (b) in (5CLTPP) 2 ZnBr 4 The tetrahedral unit in the crystal structure [ZnBr 4 ] are separated by the cation 5CLTPP to form a zero-dimensional structure.

[0057] (2) PXRD test:

[0058] The powder diffraction data were measured at 298 K using a SmartLab X-ray powder diffractometer (Cu Ka), and the powder diffraction simulation pattern was simulated based on the single crystal structure using Mercury software.

[0059] Yes (3CLTPP) 2 ZnBr 4 and (5CLTPP) 2 ZnBr 4 The crystal material was ball-milled to obtain a powder sample for PXRD testing. The results are as follows: Figure 2 As shown, Figure 2 (a) in (3CLTPP) 2 ZnBr 4 XRD pattern of crystal, Figure 2 (b) in (5CLTPP) 2 ZnBr 4 The XRD pattern of the crystal, Figure 2 (a) in (3CLTPP)2 ZnBr 4 The PXRD pattern measured by the crystal is consistent with the simulated SCXRD pattern. Figure 2 (b) in (5CLTPP) 2 ZnBr 4 The PXRD patterns of the crystals were consistent with the simulated SCXRD patterns, which confirmed that both crystalline materials were pure phases.

[0060] (3) UV-visible absorption test:

[0061] The UV-visible absorption spectrum data were measured using a UV-3600i Plus UV-visible near-infrared spectrophotometer.

[0062] Yes (3CLTPP) 2 ZnBr 4 and (5CLTPP) 2 ZnBr 4 The crystal material was tested for UV-visible absorption, and the results were as follows Figure 3 As described above, the crystalline material (3CLTPP) can be calculated 2 ZnBr 4 The band gap of (5CLTPP) is 4.2 eV. 2 ZnBr 4 The band gap is 4.26 eV.

[0063] (4) Powder frequency doubling test:

[0064] The powder SHG measurements were performed on a modified Kurtz-NLO system using a Nd:YAG laser (1064 nm) with an input pulse of 350 mV.

[0065] Yes (3CLTPP) 2 ZnBr 4 and (5CLTPP) 2 ZnBr 4 The crystal material is subjected to a powder frequency doubling test. The crystal material is sieved through a sample to a particle size of 30 um to 50 um and then subjected to a frequency doubling test. The results are as follows: Figure 4 As shown, all crystal materials have frequency doubling effect, (3CLTPP) 2 ZnBr 4 The frequency doubling performance is 0.18×KH 2 PO 4 , (5CLTPP) 2 ZnBr 4 The frequency doubling performance is 0.10×KH 2 PO 4 .

[0066] In summary, the preparation method of the present invention breaks the limitation of the conventional chiral zinc-based organic-inorganic hybrid metal halide single crystal material constructed with chiral templates, and ingeniously constructs chiral nonlinear optical crystals with non-chiral primitives. The prepared crystal has the advantages of lead-free, low toxicity, wide band gap and high stability (compared with the existing conventional metal halide crystals that decompose in one or two days at room temperature, the single crystal material of the present invention can maintain the crystal form for a long time at room temperature). The powder frequency doubling performance is 0.18×KH 2 PO 4 ((3CLTPP) 2 ZnBr 4 ) and 0.10×KH 2 PO 4 ((5CLTPP) 2 ZnBr 4 ), showing good application potential as a nonlinear optical crystal.

[0067] Comparative Example 1

[0068] A zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (6CLTPP) 2 ZnBr 4 , where 6CLTPP is a cyclohexyltriphenylphosphonium cation.

[0069] A method for preparing the zinc-based metal halide single crystal material of the comparative example comprises the following steps:

[0070] (1) In a 5 mL open glass bottle, dissolve 85.07 mg (0.2 mmol) of cyclohexyltriphenylphosphonium bromide (6CLTPPBr) and 22.52 mg (0.1 mmol) of zinc bromide in 2 mL of methanol solution and stir thoroughly at room temperature until a clear and transparent precursor solution is formed;

[0071] (2) Place the glass bottle containing the precursor solution in a 50 mL covered glass bottle containing 20 mL of ether at room temperature, cover the bottle cap, and let it stand, waiting for the ether to diffuse into the precursor solution for 36 hours to form colorless block crystals;

[0072] (3) Wash the colorless block crystals with ether and dry under reduced pressure to obtain a product with the chemical formula (6CLTPP) 2 ZnBr 4 Zinc-based metal halide single crystal materials.

[0073] In step (1), the stirring speed is 200 r / min and the stirring time is 5 min.

[0074] In step (3), the reduced pressure drying is specifically: drying at a temperature of 50° C. for 10 min under a vacuum pressure of 100 Pa.

[0075] The performance of the crystalline material obtained in this comparative example was tested according to the test methods in Examples 1 and 2, and (6CLTPP) was obtained. 2 ZnBr 4 The space group is C 2 / c , the unit cell parameters are a=23.497(3) Å, b=13.5622(14) Å, c=19.439(2) Å, β=125.262(3) o .

[0076] The crystal belongs to a centrosymmetric monoclinic space group and has a centrosymmetric structure, so it has no nonlinear optical properties.

[0077] Comparative Example 2

[0078] A zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (AETPP) 2 ZnBr 4 , where AETPP is an allyltriphenylphosphonium cation.

[0079] A method for preparing the zinc-based metal halide single crystal material of the comparative example comprises the following steps:

[0080] (1) In a 5 mL open glass bottle, dissolve 76.65 mg (0.2 mmol) of allyltriphenylphosphonium bromide (AETPPBr) and 22.52 mg (0.1 mmol) of zinc bromide in 2 mL of methanol solution and stir thoroughly at room temperature until a clear and transparent precursor solution is formed;

[0081] (2) Place the glass bottle containing the precursor solution in a 50 mL covered glass bottle containing 20 mL of ether at room temperature, cover the bottle cap, and let it stand, waiting for the ether to diffuse into the precursor solution for 36 hours to form colorless block crystals;

[0082] (3) Wash the colorless block crystals with ether and dry under reduced pressure to obtain a product with the chemical formula (AETPP) 2 ZnBr 4 Zinc-based metal halide single crystal materials.

[0083] In step (1), the stirring speed is 200 r / min and the stirring time is 5 min.

[0084] In step (3), the reduced pressure drying is specifically: drying at a temperature of 50° C. for 10 min under a vacuum pressure of 100 Pa.

[0085] The performance of the crystalline material obtained in this comparative example was tested according to the test methods in Examples 1 and 2 to obtain (AETPP) 2 ZnBr 4 The space group is C 2 / c , the unit cell parameters are a=20.1139(10) Å, b=12.8172(7) Å, c=18.6643(9) Å, β=119.872(2) o .

[0086] The crystal belongs to a centrosymmetric monoclinic space group and has a centrosymmetric structure, so it has no nonlinear optical properties.

[0087] Comparative Example 3

[0088] A zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (BETPP) 2 ZnBr 4 , where BETPP is an isopropyltriphenylphosphonium cation.

[0089] A method for preparing the zinc-based metal halide single crystal material of the comparative example comprises the following steps:

[0090] (1) In a 5 mL open glass bottle, dissolve 86.46 mg (0.2 mmol) of isopropyltriphenylphosphonium iodide (BETPPI) and 22.52 mg (0.1 mmol) of zinc bromide in 2 mL of methanol solution and stir thoroughly at room temperature until a clear and transparent precursor solution is formed;

[0091] (2) Place the glass bottle containing the precursor solution in a 50 mL covered glass bottle containing 20 mL of ether at room temperature, cover the bottle cap, and let it stand, waiting for the ether to diffuse into the precursor solution for 36 hours to form colorless block crystals;

[0092] (3) Wash the colorless block crystals with ether and dry under reduced pressure to obtain a product with the chemical formula (BETPP) 2 ZnBr 4 Zinc-based metal halide single crystal materials.

[0093] In step (1), the stirring speed is 200 r / min and the stirring time is 5 min.

[0094] In step (3), the reduced pressure drying is specifically: drying at a temperature of 50° C. for 10 min under a vacuum pressure of 100 Pa.

[0095] The performance of the crystalline material obtained in this comparative example was tested according to the test methods in Examples 1 and 2 to obtain (BETPP) 2 ZnBr 4 The space group is P 2 1 / c , the unit cell parameters are a=19.791(3) Å, b=12.487(3) Å, c=19.428(4)Å, β=98.817(4) o .

[0096] The crystal belongs to a centrosymmetric monoclinic space group and has a centrosymmetric structure, so it has no nonlinear optical properties.

[0097] Comparative Example 4

[0098] A zinc-based metal halide single crystal material, the chemical formula of the single crystal material is (DOTPP) 2 ZnBr 4 , where DOTPP is triphenylphosphonium acetal cation.

[0099] A method for preparing the zinc-based metal halide single crystal material of the comparative example comprises the following steps:

[0100] (1) In a 5 mL open glass bottle, dissolve 85.86 mg (0.2 mmol) of acetaldehyde glycol triphenylphosphonium bromide (DOTPPBr) and 22.52 mg (0.1 mmol) of zinc bromide in 2 mL of methanol solution and stir thoroughly at room temperature until a clear and transparent precursor solution is formed;

[0101] (2) Place the glass bottle containing the precursor solution in a 50 mL covered glass bottle containing 20 mL of ether at room temperature, cover the bottle cap, and let it stand, waiting for the ether to diffuse into the precursor solution for 36 hours to form colorless block crystals;

[0102] (3) Wash the colorless block crystals with ether and dry under reduced pressure to obtain a product with the chemical formula (DOTPP) 2 ZnBr 4 Zinc-based metal halide single crystals.

[0103] In step (1), the stirring speed is 200 r / min and the stirring time is 5 min.

[0104] In step (3), the reduced pressure drying is specifically: drying at a temperature of 50° C. for 10 min under a vacuum pressure of 100 Pa.

[0105] The performance of the crystalline material obtained in this comparative example was tested according to the test methods in Examples 1 and 2, and (DOTPP) was obtained.2 ZnBr 4 The space group is P 2 1 / n , the unit cell parameters are a=12.081(4) Å, b=18.119(5) Å, c=20.151(6)Å, β=91.242(10) o .

[0106] The crystal belongs to a centrosymmetric monoclinic space group and has a centrosymmetric structure, so it has no nonlinear optical properties.

[0107] In summary, although the phenylphosphonium cations used in Examples 1 to 2 and Comparative Examples 1 to 4 are all achiral units and the experimental conditions are the same, the specific phenylphosphonium cations selected in Comparative Examples 1 to 4 are different from those in Examples 1 and 2, and the chiral zinc-based metal halide single crystal material of the present invention cannot be prepared.

[0108] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solutions of the present invention without departing from the spirit and technical solutions of the present invention, or modify them into equivalent embodiments of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for preparing a chiral zinc-based metal halide single crystal material, characterized in that: The following steps are involved: (1) Dissolve the phenylphosphonium cation reagent and zinc bromide in methanol solution in an open container and stir thoroughly at room temperature to form a clear and transparent precursor solution; (2) Place the open container containing the precursor solution in a covered container containing ether at room temperature, cover it with a lid and seal it, and let it stand until the ether diffuses into the precursor solution to form colorless block crystals; (3) washing the colorless block crystals with ether and drying under reduced pressure to obtain a chiral zinc-based metal halide single crystal material; The phenylphosphonium cation reagent is cyclopropyltriphenylphosphonium bromide or cyclopentyltriphenylphosphonium bromide. When the phenylphosphonium cation reagent is cyclopropyltriphenylphosphonium bromide, the chemical formula of the chiral zinc-based metal halide single crystal material is (3CLTPP)2ZnBr4; when the phenylphosphonium cation reagent is cyclopentyltriphenylphosphonium bromide, the chemical formula of the chiral zinc-based metal halide single crystal material is (5CLTPP)2ZnBr4; in the chemical formulas (3CLTPP)2ZnBr4 and (5CLTPP)2ZnBr4 of the single crystal material, 3CLTPP is a cyclopropyltriphenylphosphonium cation, 5CLTPP is a cyclopentyltriphenylphosphonium cation, and the single crystal material is a nonlinear optical crystal belonging to the orthorhombic system; The chemical structure of (3CLTPP)2ZnBr4 is: The chemical structure of (5CLTPP)2ZnBr4 is: ； In step (1) and step (2), the molar mass volume ratio of the phenylphosphonium cation reagent, zinc bromide, methanol and diethyl ether is 0.2 mmol to 0.3 mmol: 0.1 mmol to 0.15 mmol: 2 mL to 3 mL: 20 mL to 25 mL; In step (1), the stirring speed is 200 r / min to 300 r / min, and the stirring time is 5 min to 10 min; In step (2), the diffusion time is 36 h to 48 h.

2. The method for preparing a chiral zinc-based metal halide single crystal material according to claim 1, characterized in that: In step (3), the reduced pressure drying specifically comprises: drying for at least 10 min at a temperature of 50° C. to 60° C. under a vacuum pressure of 100 Pa to 120 Pa.

3. The method for preparing a chiral zinc-based metal halide single crystal material according to claim 1, characterized in that: The tetrahedral unit [ZnBr4] in the (3CLTPP)2ZnBr4 crystal structure is separated by the cation 3CLTPP to form a zero-dimensional structure with a chiral space group. P 212121; The tetrahedral unit [ZnBr4] in the (5CLTPP)2ZnBr4 crystal structure is separated by the cation 5CLTPP to form a zero-dimensional structure, and the space group is a chiral space group P 212121.

4. The method for preparing a chiral zinc-based metal halide single crystal material according to claim 3, characterized in that: The unit cell parameters of (3CLTPP)2ZnBr4 are a=14.836(3) Å, b=16.240(3) Å, c=17.199(3) Å, α=β=γ=90 o ; The unit cell parameters of (5CLTPP)2ZnBr4 are a=15.087(3) Å, b=16.777(3) Å, c=17.377(3) Å, α=β=γ=90 o .

5. The method for preparing a chiral zinc-based metal halide single crystal material according to any one of claims 1 to 4, characterized in that: The nonlinear optical crystal is a colorless and transparent crystal. The powder frequency doubling performance of the (3CLTPP)2ZnBr4 crystal is 0.18×KH2PO4, and the powder frequency doubling performance of the (5CLTPP)2ZnBr4 crystal is 0.10×KH2PO4.

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