CN112142979A

CN112142979A - Pyramid type polyoxometallate-cage type silsesquioxane hybrid molecule and preparation method and application thereof

Info

Publication number: CN112142979A
Application number: CN202010991151.3A
Authority: CN
Inventors: 王维; 王晓静; 于成彬
Original assignee: Nankai University
Current assignee: Nankai University
Priority date: 2020-09-20
Filing date: 2020-09-20
Publication date: 2020-12-29

Abstract

A pyramid polyoxometallate-cage silsesquioxane hybrid molecule, a preparation method and application thereof. Through reasonable molecular design and multi-step organic reaction, one polyoxometallate and four cage-type silsesquioxane are connected together, and the pyramid-type polyoxometallate-cage-type silsesquioxane hybrid molecule is successfully synthesized. The hybrid is formed by covalent bond connection, so the hybrid has a fixed molecular shape, and can determine the accurate molecular weight by matrix-assisted laser desorption ionization source-time of flight mass spectrometry (MALDI-TOF-MS). in the research process of solution self-assembly, we pay more attention to the assembly process and structure change, and through a high-power transmission electron microscope, it can be observed that when the concentration is lower, the molecules self-assemble into colloidal particles, the concentration is further increased, and the colloidal particles form colloidal crystals. The structure has higher stability, and can be directly characterized by using a Transmission Electron Microscope (TEM), a Scanning Electron Microscope (SEM) and small-angle X-ray scattering (SAXS).

Description

Pyramid type polyoxometallate-cage type silsesquioxane hybrid molecule and preparation method and application thereof

Technical Field

The invention belongs to the field of synthesis of organic-inorganic hybrid molecules, and particularly relates to synthesis of a pyramid polyoxometallate-cage silsesquioxane hybrid molecule and a preparation method for constructing a colloidal crystal by the molecule.

Technical Field

Nanoparticles are quasi-zero-dimensional (0D) nanomaterials, are less than 10nm in size, and have a high surface-to-volume ratio. They are usually made of metals, inorganic oxides, semiconductors, carbon, etc. by different nanotechnology or synthetic strategies. Importantly, they have novel properties and function with size dependent properties due to quantum confinement effects. Therefore, the compounds are different from bulk solids and discrete atoms or molecules, so that the compounds become key components of electronic, photonic and biochemical sensing equipment and have wide application prospects. At the same time, nanoparticles (e.g., atoms) can form superlattices with ordered nanostructures through self-assembly, further providing opportunities for creating new advanced materials. To obtain colloidal crystals, usually by modifying ligands to the surface of the nanometal particles and then manipulating the assembly of the metal particles into a crystalline structure, it has been a challenge to assemble colloidal crystals directly from molecules in solution.

The Polyoxometalates are also called Polyoxometalates or polyacids (POM for short), and are metal oxygen cluster compounds formed by connecting early transition metal atoms in an oxygen atom coordination bridging mode, wherein the metal atoms can be molybdenum (Mo), tungsten (W), vanadium (V), titanium (Ti) and the like, the metal atoms and the oxygen atoms form MO4 tetrahedra and MO6 octahedra, and different polyhedrons are further connected in a corner-sharing, edge-sharing or coplanar mode to form a colorful Polyoxometalates structure. The metal elements and elements other than oxygen are classified into isopoly acids and heteropoly acids according to the existence of the elements, and the change of the types and the numbers of the metal atoms and the heteroatoms generates a large number of different types of multi-metal oxygen cluster structures. The polyoxometallate is simple to synthesize, can be synthesized in a large amount, and can be used as a corrosion-resistant film, a treating agent for radioactive substances, an inductor, catalysis and the like, so that the polyoxometallate has a huge development prospect. But it still has some disadvantages in itself: the difficulty of processing and the poor solubility greatly limit their use, so the development of organic modifications thereof, increasing their solubility, is a primary task.

Polyhedral oligomeric silsesquioxane (POSS) is a class of silicon oxygen cluster compounds with the general structural formula (RSiO)_3/2)_nWherein n is 6,8,10,12, R is hydrogen or an organic group such as alkyl, aryl, alkene, ester group or other functional group, etc., which are respectively called T₆，T₈，T₁₀And T₁₂Form of a cage silsesquioxane in which T₈Type cage silsesquioxane (T)₈POSS) which are the most widely used ones in the research work carried out by the man, are inorganic frameworks linked by a silicon-oxygen colloid and containing the same or different modifications of the R group on the eight apical silicon atoms, and T can be varied by varying the difference in the R groups₈Type cage silsesquioxane (T)₈POSS) physical and chemical properties.

In the field of material application, the organic construction element and the inorganic construction element are connected by a covalent bond mode, which is always a hotspot and a difficulty of research, and the organic-inorganic hybrid material obtained by the mode has the characteristics of organic property and inorganic component, and is endowed with new application performance of conventional materials.

Disclosure of Invention

The invention aims to synthesize a pyramid polyoxometallate-cage silsesquioxane hybrid molecule through reasonable molecular design according to the technical background analysis. Under specific conditions, the molecules can obtain colloidal crystals through solution self-assembly.

The technical scheme of the invention is as follows:

a pyramid-type polyoxometallate-cage-type silsesquioxane hybrid molecule has a fixed molecular shape and a determined molecular weight, and is chemically abbreviated as 4POSS-DL-POM, wherein the molecular formula of the POM is (Bu)₄N)₆H₃(P₂W₁₅V₃O₆₂) And represents a Dawson type polyoxometalate cluster, POSS represents an isobutyl-functionalized silsesquioxane type T8, and the structure of 4POSS-DL-POM is shown as follows:

the synthetic route of the preparation method of the pyramid-shaped polyoxometallate-cage-shaped silsesquioxane hybrid molecule is shown in figure 1. The peripheral counter ions of the polyoxometalate are six tetrabutylammonium positive ions and the molecular formula is (Bu)₄N)₆H₃(P₂W₁₅V₃O₆₂) Molecular weight is 5422.5; the cage type silsesquioxane is seven isobutyl functionalized T8 type silsesquioxane clusters with the molecular formula of C₃₁H₇₁NO₁₂Si₈And the molecular weight is 874.6.

The synthesis steps of the pyramid polyoxometallate-cage silsesquioxane hybrid molecule are as follows:

1) 2, will^tBu-NH₂And Fmoc-OSu substance at a ratio of 1:1.1, dissolved in THF (100mL) and stirred at room temperature for 24 h. And (5) monitoring by a point plate, and removing the solvent by spinning when the reaction is complete. Purifying by silica gel column chromatography (200-300 meshes), wherein the eluent is petroleum ether: ethyl acetate ═ 3: 1 (volume ratio), and drying to obtain a white solid 2^tBu-Fmoc (yield: 98%).

2) Selecting 2 obtained in the step 1)^tBu-Fmoc dissolved in anhydrous formic acid (100mL), stirred at room temperature for 24h until the reaction is complete, the formic acid removed, the product dispersed in ether, sonicated to disperse uniformly, a large amount of white solid precipitated, and filtered to give 2COOH-Fmoc as a white solid (yield: 85%). Selecting dried 2COOH-Fmoc and POSS-NH₂And HATU substance at a ratio of 1:3.0:3.0, dissolved in (10mL) N, N-diisopropylethylamine, stirred at room temperature for 24-72h, monitored by spotting, and washed with (50mL 10% aqueous hydrochloric acid) twice and (50mL) distilled water twice, respectively, until the reaction is complete. Drying with anhydrous sodium sulfate, removing solvent, purifying with silica gel column chromatography, eluting with dichloromethane: methanol volume ratio of 50: 1, dried to obtain 2POSS-DL-Fmoc as a white solid (yield: 90%).

3) Dissolving 2POSS-DL-Fmoc in (A), (B), (C)About 50mL) of chloroform, the diethylamine substance was slowly injected in a ratio of 1:30, the reaction was stirred at room temperature, and the solvent was removed by rotation until the reaction was complete, as monitored by dot-plate. Purifying by silica gel column chromatography, wherein the eluent is dichloromethane: methanol 15: 1 (volume ratio) to obtain white solid 2POSS-DL-NH₂(yield: 85%).

4) 2COOH-Fmoc obtained in the step 2) and 2POSS-DL-NH obtained in the step 3)₂And HATU material at a ratio of 1:2.5:2.5, dry DMF (about 10mL) and dry CHCl (about 100mL) were added sequentially₃And stirring the mixed solvent until the mixed solvent is completely dissolved. Then, N-diisopropylethylamine was slowly injected, the reaction was continuously stirred at room temperature, and the reaction was monitored by spotting, and when the reaction was completed, the reaction was sequentially washed twice with (30mL) 10% aqueous hydrochloric acid and twice with (30mL) distilled water. Drying with anhydrous sodium sulfate, removing the solvent by rotation, purifying by silica gel column chromatography (200-300 meshes), eluting with dichloromethane: methanol 50: 1 (volume ratio) and dried to obtain 4POSS-DL-Fmoc as a white solid (yield: 80%).

5) 4POSS-DL-Fmoc and diethylamine in a mass ratio of 1:30 were dissolved in chloroform (about 50mL), the reaction was stirred at room temperature, the reaction was monitored by dot-plate, and the solvent was removed by spinning off until the reaction was complete. Silica gel column chromatography (200-300 mesh), eluting with dichloromethane: methanol 15: 1 (volume ratio) to obtain white solid 4POSS-DL-NH₂(yield: 77%).

6) The 4POSS-DL-NH obtained in the step 5) is used₂Succinic anhydride and triethylamine in a mass ratio of 1:1.2:1.2, dissolved in (about 150mL) chloroform, stirred at room temperature, monitored by a dot-plate method, and extracted and washed twice with (50mL) 10% aqueous hydrochloric acid and twice with (50mL) distilled water until the reaction is completed. Drying with anhydrous sodium sulfate, removing the solvent by rotation, purifying by silica gel column chromatography (200-300 meshes), eluting with dichloromethane: methanol 15: 1 (volume ratio) to give 4POSS-DL-COOH as a white solid (yield: 80%).

7) Selecting 4POSS-DL-COOH, trihydroxymethyl aminomethane and EEDQ obtained in the step 6), dissolving the materials in trichloromethane according to the mass ratio of 1:1.5:1.5, stirring at room temperature, monitoring by using a dot plate, drying by using anhydrous sodium sulfate after complete reaction, removing the solvent by spinning, purifying by using silica gel column chromatography, wherein an eluent is dichloromethane: methanol volume ratio 15: 1, obtaining white solid 4POSS-DL-Tris (yield: 83%)

8) And synthesis of cage type silsesquioxane-polyoxometalate (4 POSS-DL-POM): step 7) obtaining 4POSS-DL-Tris and V₃The POM substance is dissolved in DMF (50mL) at a ratio of 1:1.3, and the temperature is controlled at 70-80 ℃ for reaction for 5 days to a week. And (3) removing the solvent by spinning, dissolving the residue in a small amount of tetrahydrofuran, filtering out excessive raw materials, drying by spinning, adding a large amount of acetonitrile solvent while adding a small amount of tetrahydrofuran again, centrifuging to obtain a solid precipitate, adding a large amount of diethyl ether solvent while adding a small amount of tetrahydrofuran, and centrifuging to obtain a solid precipitate. The operation was repeated 3 to 4 times to obtain 4POSS-DL-POM as a yellow solid (yield: 80%).

The invention also provides application of the pyramid polyoxometallate-cage silsesquioxane hybrid molecule for constructing colloidal crystals, and the specific preparation method comprises the following steps:

1) and preparing a precursor solution:

taking 4POSS-DL-POM hybrid molecular cluster compound as a substrate material, adding an acetone solvent and a n-decane solvent in a volume ratio of 3:2 to obtain a precursor solution sample with the concentration of 6.0 mg/mL;

2) and preparing colloidal crystals:

and (3) placing the precursor solution into a container, and volatilizing the precursor solution for 12-24 hours at 25 ℃ in an open manner to obtain a nano particle suspension solution. And dripping the solution on a carbon film, slowly volatilizing, and drying in vacuum to obtain colloidal crystals.

The advantages and the beneficial effects of the invention are as follows:

the pyramid-type cage-type silsesquioxane-polyoxometallate is obtained by taking cage-type silsesquioxane, an organic connecting chain and polyoxometallate as initial raw materials through multi-step reaction, mainly relating to amidation and polyoxometallate esterification, and finally connecting three nano-construction elements of the cage-type silsesquioxane, the connecting chain and the polyoxometallate through covalent bonds to form the hybrid molecule of the pyramid-type cage-type silsesquioxane-polyoxometallate, wherein the molecule has determined molecular weight and fixed molecular shape. The nano particles are assembled for the second time under the same condition to form colloidal crystals.

Drawings

FIG. 1 is a synthetic route diagram of a pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule.

FIG. 2 is a nuclear magnetic hydrogen spectrum of a pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule.

FIG. 3 is a time-of-flight mass spectrum of a pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule.

FIG. 4 is an ESI mass spectrum of a pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule with six negative charges.

FIG. 5 is an ESI mass spectrum of five negatively charged 4 POSS-DL-POM.

FIG. 6 is an ESI mass spectrum of a 4POSS-DL-POM with four negative charges.

FIG. 7 is a nuclear magnetic phosphorus spectrum comparison of a pyramid-shaped cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule.

FIG. 8 is a transmission electron microscope image of self-assembly of pyramid-shaped cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecules into nanoparticles.

FIG. 9 is a transmission electron microscope image of self-assembly of pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecules into colloidal crystals.

FIG. 10 is a scanning electron microscope image of the self-assembly of pyramidal polyhedral oligomeric silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecules into colloidal crystals.

FIG. 11 is a SAXS diagram of the self-assembly of pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecules into colloidal crystals.

Detailed Description

Example 1:

taking a synthesis example of a pyramid-shaped polyoxometallate-cage-shaped silsesquioxane hybrid molecule, the synthetic route is shown as figure 1, and the specific implementation steps are as follows:

step

1, 2^tSynthesis of Bu-Fmoc

2^tBu-NH₂(4.16g,10.0mmol) was dissolved in about 100mL THF, Fmoc-OSu (3.71g,11.0 mmol) was added and stirred at room temperature for 24 h. And (5) monitoring by a point plate, and removing the solvent by spinning when the reaction is complete. Purifying by silica gel column chromatography (200-300 meshes), wherein the eluent is petroleum ether: ethyl acetate ═ 3: 1 (volume ratio), dried to give 6.25g of white solid 2^tBu-Fmoc (yield: 98%).

Step 2, synthesis of POSS-DL-Fmoc

Selecting 2 obtained in the step 1)^tBu-Fmoc (2.62g, 5.0mmol), dissolved in 100mL of anhydrous formic acid, stirred at room temperature for 24h until the reaction is complete, and the formic acid removed. About 30mL of toluene was then added to the residue, followed by spin-drying, which was repeated twice to strip out residual formic acid. The crude product obtained is dispersed in about 30mL of diethyl ether, and is dispersed uniformly by ultrasonic treatment, and a large amount of white solid is separated out. The Buchner funnel was suction-filtered and vacuum-dried to obtain 1.75g of a white solid, 2COOH-Fmoc (yield: 85%).

Dried 2COOH-Fmoc (1.75g,4.3mmol), POSS-NH was selected₂(11.28g,12.9mmol), HATU (4.90g,12.9mmol) and N, N-diisopropylethylamine (7.11mL), about 25mL dry DMF and about 150mL dry CHCl were added₃And stirring the mixed solvent until the mixed solvent is completely dissolved. The reaction was stirred for an additional 36h at room temperature. And (5) monitoring by using a point plate, and sequentially carrying out extraction washing twice by using 50mL of 10% hydrochloric acid aqueous solution and extraction washing twice by using 50mL of distilled water when the reaction is complete. Drying with anhydrous sodium sulfate, removing the solvent by rotation, purifying by silica gel column chromatography (200-300 meshes), eluting with dichloromethane: methanol 50: 1 (volume ratio) to yield 8.22g of 2POSS-DL-Fmoc as a white solid (yield: 90%).

Step 3), 2POSS-DL-NH₂Synthesis of (2)

2POSS-DL-Fmoc (8.22g,3.9mmol) obtained in step 2) was dissolved in about 50mL of chloroform, and diethylamine (8.56g,117.0mmol) was slowly injected and the reaction was stirred at room temperature for 5 h. And (5) monitoring by a point plate, and removing the solvent by spinning when the reaction is complete. Silica gel column chromatography (200-300 mesh), eluting with dichloromethane: methanol 15: 1 (volume ratio) to give 6.31g of 2POSS-DL-NH as a white solid₂(yield: 85%).

Step 4), synthesis of 4POSS-DL-Fmoc

2COOH-Fmoc (0.41g,1.0mmol) obtained in the step 2) and 2POSS-DL-NH obtained in the step 3)₂(4.76g,2.5mmol) and HATU (0.95g,2.5mmol) were added sequentially about 10mL of dried DMF and about 100mL of dried CHCl₃And stirring the mixed solvent until the mixed solvent is completely dissolved. N, N-diisopropylethylamine (1.65mL) was then slowly injected and the reaction was stirred at room temperature for an additional 36 h. And (5) monitoring by using a point plate, and sequentially carrying out extraction washing twice by using 30mL of 10% hydrochloric acid aqueous solution and extraction washing twice by using 30mL of distilled water when the reaction is complete. Drying with anhydrous sodium sulfate, removing the solvent by rotation, purifying by silica gel column chromatography (200-300 meshes), eluting with dichloromethane: methanol 50: 1 (volume ratio), dried to yield 3.34g of 4POSS-DL-Fmoc as a white solid (yield: 80%).

Step 5), 4POSS-DL-NH₂Synthesis of (2)

Using 4POSS-DL-Fmoc (3.34g,0.8mmol) obtained in step 4), dissolved in about 50mL of chloroform, and diethylamine (1.75g,24.0mmol), the reaction was stirred at room temperature for 5 h. And (5) monitoring by a point plate, and removing the solvent by spinning when the reaction is complete. Silica gel column chromatography (200-300 mesh), eluting with dichloromethane: methanol 15: 1 (volume ratio) to yield 2.44g of 4POSS-DL-NH as a white solid₂(yield: 77%).

Step 6) synthesis of 4POSS-DL-COOH

With the 4POSS-DL-NH obtained in step 5)₂(1.98g,0.5mmol) was dissolved in about 150mL of chloroform, succinic anhydride (0.06g,0.6mmol) and triethylamine (0.06g,0.6mmol) were added, and the reaction was stirred at room temperature for 36 h. And (5) monitoring by using a point plate, and sequentially carrying out extraction washing twice by using 50mL of 10% hydrochloric acid aqueous solution and extraction washing twice by using 50mL of distilled water when the reaction is complete. Drying with anhydrous sodium sulfate, removing the solvent by rotation, purifying by silica gel column chromatography (200-300 meshes), eluting with dichloromethane: methanol 15: 1 (volume ratio), 1.63g of 4POSS-DL-COOH was obtained as a white solid (yield: 80%).

Step 7), synthesis of 4POSS-DL-Tris

4POSS-DL-COOH (2.02g,0.5mmol) obtained in the step 6), tris (hydroxymethyl) aminomethane (0.091 g,0.75mmol) and EEDQ (0.19g,0.75mmol) were selected and reacted for 36 hours under reflux. After completion of the reaction, the solvent was removed by rotation, and the residue was washed twice with dichloromethane (150 mL) and saturated brine (50mL), separated, and dried over anhydrous sodium sulfate. Removing the solvent by spinning, purifying by silica gel column chromatography (100-200 meshes), wherein the eluent is dichloromethane: methanol 15: 1 (volume ratio), to give 1.72g of 4POSS-DL-Tris as a white solid (yield: 83%)

Step 8), synthesis of 4POSS-DL-POM

Synthesis of cage type silsesquioxane-polyoxometalate (4 POSS-DL-POM): 4POSS-DL-Tris (1.24g,0.3mmol) obtained in step 7), V₃POM (2.11g,0.39mmol) was dissolved in 50mL of DMF and reacted at 80 ℃ for 5 days. And (3) removing the solvent by spinning, dissolving the residue in a small amount of tetrahydrofuran, filtering out excessive raw materials, drying by spinning, adding a large amount of acetonitrile solvent while adding a small amount of tetrahydrofuran again, centrifuging to obtain a solid precipitate, adding a large amount of diethyl ether solvent while adding a small amount of tetrahydrofuran, and centrifuging to obtain a solid precipitate. The operation was repeated 3 to 4 times to obtain 2.58g of 4POSS-DL-POM as a yellow solid (yield: 80%).

Fig. 2 is a nuclear magnetic hydrogen spectrum of a pyramid type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule, from which we can determine the number of hydrogens on the hybrid molecule corresponding to each peak and assign each peak, which is the first evidence we determined successful synthesis of the hybrid molecule.

FIG. 3 is a time-of-flight mass spectrum of a pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecule. In this spectrum we obtained several peaks, 9530.07 (the molecule gave a proton hydrogen) and 9771.63 (the molecule gave a tetrabutylammonium), calculated as 9530.20 and 9771.66, respectively, which match the calculated values, which is the second evidence we determined to successfully synthesize the hybrid molecule.

FIG. 4 is the ESI of the six negatively charged 4POSS-DL-POM molecular ion peaks. FIG. 5 is the ESI of the five negatively charged 4POSS-DL-POM molecular ion peaks and FIG. 6 is the ESI of the four negatively charged 4POSS-DL-POM molecular ion peaks, which are all matched by the calculated values, which is the third evidence we have determined to be successful in synthesizing the hybrid molecule.

FIG. 7 is a comparison of nuclear magnetic phosphorus spectra of pyramid-type cage silsesquioxane-polyoxometalate (4POSS-DL-POM) hybrid molecules, from which we found a peak shift of 0.33ppm and no other impurity peaks, indicating that the polyoxometalate has reacted to completion, which is the fourth evidence we determined to successfully synthesize the hybrid molecules.

Example 2:

and (3) preparing a colloidal crystal of the pyramid type cage silsesquioxane-polyoxometalate hybrid molecule.

1) Preparing a precursor solution:

weighing 6mg of 4POSS-DL-POM hybrid molecules serving as substrate materials, adding 600 mu L of acetone solvent and 400 mu L of n-decane solvent to obtain a precursor solution with the total volume of 1.0mL and the sample concentration of 6.0 mg/mL;

2) preparation of colloidal crystals:

and (3) placing the precursor solution into a 2.0mL sample bottle, and volatilizing the solution for 12 hours at 25 ℃ in an open manner to obtain a nano particle suspension solution. And dripping the solution on a carbon film, slowly volatilizing, and drying in vacuum to obtain colloidal crystals.

The invention focuses on the assembly process and structural change, the opening is placed in the mixed solution of acetone and n-decane, acetone volatilizes, the assembly is slowly carried out, when the concentration is lower, the molecules are self-assembled into colloid particles through a high-power transmission electron microscope, when the concentration is increased, the colloid particles are gathered into a small crystal domain structure, the concentration is further increased, the colloid particles are observed to grow until crystal domains are mutually connected to form polycrystal, and then the crystal domains enter a curing (ripening) stage, namely the small crystal domains gradually return to the large crystal domains, so that the crystal domain interface can be reduced to form colloid crystals. The structure has higher stability, and can be directly characterized by using a Transmission Electron Microscope (TEM), a Scanning Electron Microscope (SEM) and small-angle X-ray scattering (SAXS). Compared with the common crystal, the colloidal crystal can be used as a photonic crystal, presents rich colors, can be used for the fields of manufacturing sensors and the like, and can also be used as a template of a macroporous material to prepare various macroporous materials.

Claims

1. A pyramid-type polyoxometallate-cage-type silsesquioxane hybrid molecule has precise molecular weight and fixed molecular shape, and is chemically abbreviated as 4POSS-DL-POM, wherein the molecular formula of the POM is (Bu)₄N)₆H₃(P₂W₁₅V₃O₆₂) And represents a Dawson type polyoxometalate cluster, POSS represents isobutyl-functionalized T8 type silsesquioxane, and the structural formula of 4POSS-DL-POM is as follows:

2. the preparation method of the pyramid polyoxometallate-cage silsesquioxane hybrid molecule as claimed in claim 1, wherein the starting materials are Dawson polyoxometallate, di-tert-butylfluorenylmethoxycarbonyl and monoamino modified isobutyl T8 silsesquioxane,

1) will 2^tBu-NH₂And Fmoc-OSu, the mass ratio of the substances is 1:1.1, the mixture is dissolved in THF, stirred at room temperature, monitored by a dot-plate mode, and subjected to rotary removal of a solvent after complete reaction and silica gel column chromatography purification, wherein an eluent is petroleum ether: ethyl acetate volume ratio 3: 1, drying to obtain a white solid 2^tBu-Fmoc；

2) Option 2^tDissolving Bu-Fmoc in anhydrous formic acid, stirring at room temperature, removing formic acid, dispersing the obtained product in diethyl ether, performing ultrasonic treatment to uniformly disperse the product, separating out a large amount of white solid, filtering to obtain white solid 2COOH-Fmoc, and mixing 2COOH-Fmoc and POSS-NH₂And HATU, the mass ratio of the substances is 1:3.0:3.0, the substances are dissolved in N, N-diisopropylethylamine and stirred for 24-72h at room temperature to obtain white solid 2 POSS-DL-Fmoc;

3)2POSS-DL-Fmoc is dissolved in trichloromethane, diethylamine is slowly injected, the mixture is stirred at room temperature, the mixture is subjected to plate spotting monitoring, and after the reaction is completed, the solvent is removed by rotation; purifying by silica gel column chromatography, wherein the eluent is dichloromethane: methanol volume ratio 15: 1, obtaining white solid 2POSS-DL-NH₂；

4) 2COOH-Fmoc obtained in the step 2) and 2POSS-DL-NH obtained in the step 3)₂And HATU in a ratio of 1:2.5:2.5, adding dried DMF and dried CHCl sequentially₃Stirring the mixed solvent until the mixed solvent is completely dissolved; then slowly injecting N, N-diisopropylethylamine, continuously stirring at room temperature for reaction, performing point-plate monitoring, sequentially performing extraction washing twice with 10% hydrochloric acid aqueous solution and extraction washing twice with distilled water after the reaction is complete, drying with anhydrous sodium sulfate, removing the solvent by rotation, and purifying by silica gel column chromatography, wherein the eluent is dichloromethane: methanol volume ratio of 50: 1, drying to obtain white solid 4 POSS-DL-Fmoc;

5) dissolving 4POSS-DL-Fmoc and diethylamine in chloroform at a mass ratio of 1:30, stirring at room temperature, monitoring by using a dot-plate, removing the solvent by rotation when the reaction is complete, purifying by using silica gel column chromatography, wherein the eluent is dichloromethane: methanol volume ratio 15: 1, obtaining white solid 4POSS-DL-NH₂；

6) 4POSS-DL-NH obtained in the step 5)₂Succinic anhydride and triethylamine with the mass ratio of 1:1.2:1.2 are dissolved in chloroform, stirred at room temperature, monitored by a dot-plate mode, and after the reaction is completed, sequentially washed twice by 10% hydrochloric acid aqueous solution and twice by distilled water, dried by anhydrous sodium sulfate, removed with solvent by spinning, purified by silica gel column chromatography, and the eluent is dichloromethane: methanol volume ratio 15: 1, obtaining white solid 4 POSS-DL-COOH;

7) dissolving the 4POSS-DL-COOH, the tris (hydroxymethyl) aminomethane and the EEDQ obtained in the step 6) in chloroform at a mass ratio of 1:1.5:1.5, stirring at room temperature, monitoring by a dot plate, drying with anhydrous sodium sulfate after complete reaction, removing the solvent by rotation, purifying by silica gel column chromatography, wherein an eluent is dichloromethane: methanol volume ratio 15: 1, obtaining white solid 4 POSS-DL-Tris;

8) synthesis of cage type silsesquioxane-polyoxometalate (4 POSS-DL-POM): step 7) obtaining 4POSS-DL-Tris and V₃POM, the mass ratio of substances is 1:1.3, the POM is dissolved in DMF, the temperature is controlled at 70-80 ℃, the reaction lasts for 5 days to a week, the solvent is removed by rotation, the residue is dissolved in a small amount of tetrahydrofuran, the excessive raw materials are filtered, the solvent is dried by rotation, the tetrahydrofuran and the acetonitrile solvent are added again, the solid precipitate is obtained by centrifugation, then a large amount of ether solvent is added while a small amount of tetrahydrofuran is added, the solid precipitate is obtained by centrifugation, and the operation is repeated for 3-4 times to obtain yellow solid 4 POSS-DL-POM.

3. The application of the pyramid polyoxometallate-cage silsesquioxane hybrid molecule of claim 1 in constructing colloidal crystals, which is prepared by the following steps:

1) preparation of precursor solution

Taking 4POSS-DL-POM hybrid molecules as a substrate material, adding an acetone solvent and a n-decane solvent in a volume ratio of 3:2 to obtain a precursor solution sample with the concentration of 6.0 mg/mL;

2) preparation of colloidal crystals

And placing the precursor solution in a container, volatilizing the precursor solution for 12-24 hours at room temperature in an open manner, dripping the solution onto a carbon film, slowly volatilizing, and drying in vacuum to obtain the colloidal crystal.