CN115417384B - Preparation method of chiral tellurium (Te) nanocrystalline material - Google Patents

Abstract

The invention provides a preparation method of chiral tellurium (Te) nano crystal material. It uses the chiral ligand cysteine (L-cys/D-cys) as an inducer, at a temperature of 180 ° C, in the presence of hydrazine hydrate (N ₂ H ₄ ) and polyvinylpyrrolidone (PVP) Sodium tellurite (Na ₂ TeO ₃ ) is reduced in an alkaline solution, and under the action of chiral ligands, a chiral morphology is generated to produce a chiral characteristic L‑cys+Te/D‑cys+Te double cone Body-shaped nanocrystals. The chiral Te nanocrystal of the present invention has obvious chiral characteristics and good stability, and is different from other chiral induction methods in terms of convenience and quickness. The method of the invention has simple raw materials, good stability, simple operation, is suitable for large-scale production, and has broad application prospects.

Description

A kind of preparation method of chiral tellurium (Te) nanocrystal material

technical field

The invention relates to the technical field of inorganic chemistry, in particular to a chiral tellurium (Te) nano crystal material and a preparation method thereof.

Background technique

In recent years, chiral inorganic materials have been developed rapidly as an important branch of chiral materials. Due to their special properties, inorganic nanomaterials such as quantum dots, transition metal oxides, and metal nanoparticles have been widely used in chiral sensors, cell imaging, and circularly polarized light-emitting devices. Group VI tellurium (Te) is a member of the chalcogen group. Each tellurium atom is covalently bonded to the two nearest neighbor tellurium atoms, and based on this, a unique chiral chain structure is formed, and then a triangular helix is formed. structure crystal. Under the action of van der Waals forces, the helical chains of tellurium atoms are stacked together in a hexagonal array, forming a layered structure, and rotate around an axis parallel to the [0001] direction at the center and corners of the hexagonal unit cell. A chiral molecule is one whose configuration and its mirror image do not completely overlap in three dimensions, so the mirror image forms of chiral molecules are classified as enantiomers. Chirality is one of the key factors for molecular recognition. Because nanocrystals typically have low symmetry due to chiral defects in the bulk and surface, potentially any nanocrystal can be chiral. But in solution, because the chirality of nanocrystals is random, nanocrystals usually do not exhibit circular dichroism macroscopically. Cysteine (Cys) and its derivatives are widely used as ligands for the synthesis of chiral inorganic nanocrystals. By systematically exploring the synthesis factors, chiral inorganic nanocrystals can be easily designed and fabricated. In spectroscopy, circular dichroism (CD) and rotational dispersion methods are used to detect subtle structural changes in chiral molecules. The nature of the different chirality responses to left-handed and right-handed circularly polarized photons of a mirror-image chiral molecule provides us with the opportunity to measure molecular chirality using optical CD methods. The chirality of inorganic nanocrystals is mainly obtained from the following three mechanisms: (i) shape chirality and lattice chirality in chiral crystals; (ii) interaction between achiral nanocrystals and chiral molecules; (iii) Chiral assembled structures of achiral nanocrystals.

Hydrothermal method is an efficient and fast synthetic method to prepare traditional Te nanostructures. Sodium tellurite (Na ₂ TeO ₃ ) was reduced by hydrazine hydrate (N ₂ H ₄ ) in alkaline solution at 180°C and growth of tellurium nanostructures in the presence of the facet-blocking ligand polyvinylpyrrolidone (PVP) . On this basis, by adding chiral molecules at an appropriate time point and fine-tuning the alkalinity of the solution and the concentration of hydrazine hydrate, a large number of tellurium nanocrystals with chiral properties can be prepared conveniently and quickly. Due to the influence of chiral molecules, tellurium nanowires or nanosheets will no longer be produced, but bipyramidal tellurium nanocrystals with chiral properties will be produced. The crystal size is about 200-300nm, the property is relatively stable, and it is not easy to be oxidized.

At present, the existing chiral induction schemes can be divided into three types. (i) Chiral self-assembly/configuration. That is, rod-helical self-assembly is performed by template-assisted various points. For example, using the nano-silica helical structure as a template to synthesize a 3D chiral helical superstructure of gold nanoparticles, the structure exhibits strong plasmonic chiral activity. In the co-self-assembly system, the chiral template interacts with the nanoparticles, the chiral template can endow the nanoparticles with chirality, and the nanoparticles can also affect the chiral structure of the template. (ii) Achiral nanoparticles coated with chiral molecules on the surface. That is, a weak chiral transfer effect is generated through the interaction of chiral molecules with achiral metals or semiconductors. For example, L-cysteine/D-cysteine is used to construct wurtzite crystal CdSe quantum rods, so that the quantum rods have unique optical anisotropy and stronger CD response. (iii) Shape chirality and lattice chirality in chiral crystals. That is, the enantioselective control of lattice and shape chirality in inorganic nanostructures by chiral biomolecules is used to synthesize nanostructures with chiral shape and optical activity. The present invention formally uses chiral molecules (cysteine) to grow into crystals with chiral shapes during the synthesis process of Te nanocrystals, thereby having chiral optical activity and CD response.

Contents of the invention

The technical problem to be solved by the present invention is to make the tellurium (Te) nanostructures without chiral properties have chiral properties, and compared with the existing chiral induction method, the operation is simpler and the yield is higher.

In order to solve the above technical problems, the present invention provides a chiral Te nanocrystal material and a preparation method thereof. Using the chiral ligand cysteine as _an inducer, the reduction of sodium _tellurite ( Na ₂ TeO ₃ ), under the action of chiral ligands, generate Te nano-bipyramidal crystals with chiral morphology and chiral characteristics.

The invention provides a preparation method of a chiral Te nanocrystal material, comprising the following steps;

A. Preparation of L-cys+Te nanocrystal material with chiral characteristics:

A-1. Dissolve 0.125~1.5g of polyvinylpyrrolidone (PVP) with a molecular weight of 8K~1300K in 25~40ml of deionized water and stir for 3-5min to fully dissolve the PVP. Sodium tellurite (Na ₂ TeO ₃ ) The mass ratio of polyvinylpyrrolidone (PVP) is Na ₂ TeO ₃ : PVP=1:1.25~30;

A-2. Add 0.05~0.1g of sodium tellurite into the solution in step A-1, stir for 3-5min to fully dissolve;

A-3. Add 0.1~0.8g of cysteine (L-cys) into the solution in step A-2, stir for 3-5min to fully dissolve;

A-4. Take 1.5~5ml of ammonia water and add it to the solution in step A-3;

A-5. Add 0.5~3ml of hydrazine hydrate to step A-4;

A-6. Stir the solution in step A-5 for 10mim and put it in the reactor at 150~210°C for 3~21h, then cool to room temperature and take it out;

A-7. Centrifuge the solution in step A-6 three times with deionized water and twice with ethanol at a centrifugal speed of 4000~8000rpm/min for 5 minutes, and finally redisperse it in 3mL of deionized water. The obtained crystal is named hand Sexual L-cys+Te nanocrystals.

B. Preparation of D-cys+Te nanocrystal materials with chiral properties:

Steps B-1, B-2, B-4, B-5, B-6, B-7 and said steps A-1, A-2, A-4, A-5, A-6, A- 7 are exactly the same;

The step B-3 is to add 0.1-0.8 g of cysteine (D-cys) into the solution in step B-2, and stir for 3-5 minutes to fully dissolve;

The crystals obtained in the step B-7 are named as chiral D-cys+Te nanocrystals;

The chiral L-cys+Te nanocrystal and the chiral D-cys+Te nanocrystal are a pair of chiral crystal materials.

A preparation method of a further optimized chiral Te nanocrystal material, specifically comprising the following steps:

A. Preparation of L-cys+Te nanocrystal material with chiral characteristics:

A-1. Dissolve 1.0000g of polyvinylpyrrolidone (PVP) with a molecular weight of 58k in 33ml of deionized water and stir for 3-5min to fully dissolve the PVP. Sodium tellurite (Na ₂ TeO ₃ ) and polyvinylpyrrolidone (PVP) ) The mass ratio is Na ₂ TeO ₃ :PVP=1:10.8;

A-2. Add 0.0922g of sodium tellurite into the solution in step A-1, stir for 3-5min to fully dissolve;

A-3. Add 0.2272g of cysteine (L-cys) to the solution in step A-2, stir for 3-5 minutes to fully dissolve;

A-4, take 3.33ml of ammonia water and add it to the solution in step A-3;

A-5, take 1.67ml of hydrazine hydrate and add it to the solution in step A-4;

A-6, A-5 was stirred for 10mim and put into the reactor at 180°C for 18h, then cooled to room temperature and taken out;

A-7. Centrifuge the solution of A-6 three times with deionized water and twice with ethanol at a centrifugation speed of 6000rpm/min for 5 minutes, and finally redisperse it in 3mL deionized water. The crystal obtained is named chiral L- cys+ nanocrystals.

B. Preparation of D-cys+Te nanocrystal materials with chiral properties:

Steps B-1, B-2, B-4, B-5, B-6, B-7 and steps A-1, A-2, A-4, A-5, A-6, A-7 is exactly the same;

Step B-3 is to add 0.2272g of cysteine (D-cys) into the solution in step B-2, and stir for 3-5 minutes to fully dissolve;

The obtained crystal in step B-7 is named chiral D-cys+Te nanocrystal;

The chiral L-cys+Te nanocrystal and the chiral D-cys+Te nanocrystal are a pair of chiral crystal materials.

Compared with the prior art, the technical solution of the present invention has the following advantages:

(1) Compared with the preparation of Te nanostructures by the traditional hydrothermal method, Te nanocrystals with chiral properties are induced from Te without chiral properties through chiral ligands;

(2) Transform the Te nanowire or nanosheet structure prepared by the traditional hydrothermal method into a nanocrystalline structure;

(3) Compared with the existing chiral induction scheme, it is simpler and more convenient, and the chirality of Te is induced from the steps of Te synthesis and preparation;

(4) The chiral ligands of the chiral Te nanocrystal material described in the present invention are cysteine (L-cys) and cysteine (D-cys), and the chiral ligands can form Two different growth directions, resulting in two configurations of materials;

(5) The method of the present invention has simple raw materials, good stability, simple operation, is suitable for large-scale production, and has broad application prospects.

Description of drawings

Fig. 1 is the SEM figure of the chiral L-cys+Te nanocrystal and D-cys+Te nanocrystal that the embodiment of the present invention 1,2 makes;

Wherein A is the SEM figure of the morphology of L in the L-cys+Te nanocrystal material of chiral shape, B is the SEM figure of the morphology of D in the D-cys+Te nanocrystal material of chiral shape, the two By comparison, it can be clearly seen that the Te nanocrystals have a bipyramidal morphology with obvious chiral symmetry.

Fig. 2 is CD, UV diagram and g-factor diagram of chiral L-cys+Te nanocrystal and D-cys+Te nanocrystal prepared in Examples 1 and 2 of the present invention;

Among them, A, B, and C are the chiral L-cys+Te nanocrystals and D-cys+Te nanocrystals CD, UV and g-factor maps that were reacted for 18 hours in the implementation case 1; D, E, and F are the implementation case 2 CD, UV and g-factor diagrams of chiral L-cys+Te nanocrystals and D-cys+Te nanocrystals of polyvinylpyrrolidone (PVP 58000).

Detailed ways:

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

Experimental material

Polyvinylpyrrolidone (PVP), sodium tellurite (Na ₂ TeO ₃ , 99.9%), ammonia water (25%, w/w%), hydrazine hydrate (85%, w/w%), L-cysteine (L-cysteine, 98.5%) and D-cysteine (D-cysteine, 99%) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

Example 1

Chiral Te nanocrystals prepared with different reaction times:

1) Weigh 1.000g of PVP (molecular weight 58K), then add 33mL of deionized aqueous solution, stir well, add 0.0922g of Na ₂ TeO ₃ and stir well, then add 0.2272g of cysteine (L-cys or D -cys) Stir evenly, then take 3.33ml of ammonia water and 1.67ml of hydrazine hydrate and add it, stir for 10 minutes, put it into the liner and put it into the reaction kettle, and react in the oven at 180°C for 3h, 7h, 11h, 15h, 18h, 21h, Take out after cooling;

2) After the reaction, first centrifuge at 6000rpm/min for 5min, centrifuge three times with deionized water, centrifuge twice with ethanol, and finally redisperse in 3mL deionized water. That is, L-cys+Te and D-cys+Te nanocrystal materials with obvious configuration are obtained. The prepared chiral Te nanocrystal material was characterized by scanning electron microscopy, and the test results are shown in Figure 1. The prepared chiral Te nanocrystal material was tested by circular dichroism spectrometer and the g-factor calculation results were shown in Figure 2. A , B, C shown.

Example 2

Weigh 1.000g of PVP (molecular weights are 8000, 10000, 24000, 40000, 58000, 1300000), then add 33mL of deionized aqueous solution for each part, stir well, add 0.0922g of Na ₂ TeO ₃ and stir well, then add 0.2272 g of cysteine (L-cys or D-cys) and stir evenly, then take 3.33ml of ammonia water and 1.67ml of hydrazine hydrate and add, stir for 10min, put it into the liner and put it into the reaction kettle, and react in the oven at 180°C 18h, take out after cooling;

After the reaction, centrifuge at a speed of 6000rpm/min for 5min, centrifuge three times with deionized water, centrifuge twice with ethanol, and finally redisperse in 3mL water for later use. That is, L-cys+Te and D-cys+Te nanocrystal materials with obvious configuration are obtained. The prepared chiral Te nanocrystal material was characterized by scanning electron microscopy and the test results are shown in Figure 1. The chiral Te nanocrystal material prepared under the condition of 58000 was tested by circular dichroism spectrometer and the g-factor calculation results were shown in Figure 2 Shown in D, E, F.

Claims (2)

1. A preparation method of chiral tellurium Te nanocrystal material, is characterized in that specifically comprising the following steps; A. Preparation of L-cys+Te nanocrystal material with chiral characteristics: A-1. Dissolve 0.125~1.5g of polyvinylpyrrolidone PVP with a molecular weight of 8K~1300K in 25~40ml of deionized water and stir for 3-5min to fully dissolve the PVP. Sodium tellurite Na ₂ TeO ₃ and polyethylene The mass ratio of pyrrolidone to PVP is Na ₂ TeO ₃ : PVP=1:1.25~30; A-2. Add 0.05~0.1g of sodium tellurite into the solution in step A-1, stir for 3-5min to fully dissolve; A-3. Add 0.1~0.8g of cysteine L-cys into the solution in step A-2, stir for 3-5min to fully dissolve; A-4. Take 1.5~5ml of ammonia water and add it to the solution in step A-3; A-5. Add 0.5~3ml of hydrazine hydrate to step A-4; A-6. Stir the solution in step A-5 for 10mim and put it in the reactor at 150~210°C for 3~21h, then cool to room temperature and take it out; A-7. Centrifuge the solution in step A-6 three times with deionized water and twice with ethanol at a centrifugal speed of 4000~8000rpm/min for 5 minutes, and finally redisperse it in 3mL of deionized water. The obtained crystal is named hand Sexual L-cys+Te nanocrystals; B. Preparation of D-cys+Te nanocrystal materials with chiral properties: Steps B-1, B-2, B-4, B-5, B-6, B-7 and the above steps A-1, A-2, A-4, A-5, A-6, A -7 is exactly the same; Step B-3 is to add 0.1~0.8g of cysteine D-cys into the solution in step B-2, and stir for 3-5min to fully dissolve; The crystals obtained in the step B-7 are named as chiral D-cys+Te nanocrystals; The chiral L-cys+Te nanocrystal and the chiral D-cys+Te nanocrystal are a pair of chiral crystal materials. 2. the preparation method of a kind of chiral tellurium Te nanocrystal material according to claim 1, is characterized in that specifically comprising the following steps: A. Preparation of L-cys+Te nanocrystal material with chiral characteristics: A-1. Dissolve 1.0000g of polyvinylpyrrolidone PVP with a molecular weight of 58K in 33ml of deionized water, and stir for 3-5min to fully dissolve the PVP; A-2. Add 0.0922g of sodium tellurite into the solution in step A-1, stir for 3-5min to fully dissolve; A-3. Add 0.2272g of cysteine L-cys to the solution in step A-2, and stir for 3-5 minutes to fully dissolve; A-4, take 3.33ml of ammonia water and add it to the solution in step A-3; A-5, take 1.67ml of hydrazine hydrate and add it to the solution in step A-4; A-6. Stir A-5 for 10mim and put it in the reactor at 180°C for 11-18h, then cool to room temperature and take it out; A-7. Centrifuge the solution of A-6 three times with deionized water and twice with ethanol at a centrifugation speed of 6000rpm/min for 5 minutes, and finally redisperse it in 3mL deionized water. The crystal obtained is named chiral L- cys+Te nanocrystals; B. Preparation of D-cys+Te nanocrystal materials with chiral properties: Steps B-1, B-2, B-4, B-5, B-6, B-7 and steps A-1, A-2, A-4, A-5, A-6 described in this claim , A-7 are exactly the same; Step B-3 is to add 0.2272g of cysteine D-cys into the solution in step B-2, and stir for 3-5 minutes to fully dissolve; The obtained crystal in step B-7 is named chiral D-cys+Te nanocrystal; The chiral L-cys+Te nanocrystal and the chiral D-cys+Te nanocrystal are a pair of chiral crystal materials.

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