A chiral metal coordination-based tetraphenyl ethylene chiral metal cage complex and a preparation method and application thereof

Abstract

This invention discloses a chiral Pt metal-organic complex based on chiral Pt metal coordination, its preparation method, and its applications, belonging to the field of supramolecular chemistry. This method transfers chirality from the metal node to the tetraphenylethylene plane through metal coordination, forming a helical structure during crystallization to obtain a high-performance circularly polarized luminescent material. The introduction of a chiral binaphthyl group solves the problem of excessive distance between the chirality and the luminescent unit. Rigid coordination and steric effects are used to directionally induce a helical conformation in tetraphenylethylene, obtaining a single chiral molecule. Furthermore, this method connects the chiral group via covalent bonds and uses aggregation-induced emission molecules instead of traditional dyes to prepare materials with both a large luminescence asymmetry factor and high fluorescence quantum yield, expanding the application range of metal-organic cages.

Description

Technical Field

[0001] This invention belongs to the field of supramolecular chemistry, specifically relating to a chiral Pt metal coordination-based tetraphenylethylene chiral metal cage complex, its preparation method, and its application. Background Technology

[0002] Chiral circularly polarized luminescent (CPL) materials, as carrier materials for next-generation optical technology platforms, have wide applications in information storage, 3D display, and chiral optoelectronics. Organic CPL materials have attracted much attention due to their tunable emission wavelength, good solution processability, and flexibility. However, the weak spin-orbit coupling and electrically transition-dominated luminescence of organic materials significantly limit their performance as CPL materials, including their asymmetry factor (…). g lum ) and fluorescence quantum yield ( Φ Therefore, the development of large-scale... g lum and high Φ The availability of CPL materials has become an urgent problem to be solved.

[0003] Currently, the main types of organic CPL materials prepared are: chiral organic small molecules, chiral polymers, chiral lanthanide metal complexes, chiral organic liquid crystals, and chiral metal-organic cages. To obtain CPL luminescent materials with good performance, their structure must meet the following three requirements: first, a stable chiral conformation to ensure stability at the molecular scale without racemization; second, good luminescence in the solid state; and third, molecular stacking to form a helical superstructure adapted to visible light wavelengths (400-800 nm). Among these, metal-organic cages, with their advantages of multi-component synergy, precise structural tunability, and simple synthesis, are strong candidates for CPL materials.

[0004] Previously, the main strategy for chiral metal-organic cages was to separate the chiral units from the emitting units and connect them via coordination bonds through metal nodes. For example, chiral ligands and achiral dye ligands self-assembled into a chiral cage, and the light emitted by the achiral dye could be circularly polarized through the chiral transfer effect. However, because the ligands were relatively far apart due to the metal nodes separating them, the chiral transfer efficiency was low, resulting in chiral metal-organic cages with low efficiency. g lum The emission is relatively small. Furthermore, the weak luminescence in the aggregated state due to the severe aggregation-induced quenching effect of common organic dyes is another drawback. Therefore, solving these problems makes chiral metal-organic cages a valuable scientific research material for CPL luminescence. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex, its preparation method, and its application, thereby solving the problem of metal cages in the prior art. g lum Smaller and Φ Lower-level issues.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a chiral Pt metal cage-like complex based on chiral Pt metal coordination, wherein the chiral Pt metal cage-like complex is obtained by self-assembly of a tetradentate sodium carboxylate ligand, a chiral Pt metal ion, and a tetrapyridyl tetraphenylethylene ligand. During the self-assembly process, the chiral Pt metal ion removes two trifluoromethanesulfonate groups and then binds to a pyridine coordination site and a carboxylic acid coordination site. The tetradentate sodium carboxylate ligand has the following structural formula:

[0007] (I) The structural formula of the tetrapyridyltetraphenylethylene ligand is:

[0008] (II) The structural formula of the chiral Pt metal ion is:

[0009] (III).

[0010] A further improvement of the present invention is that: Preferably, the molar ratio of the tetradentate sodium carboxylate organic ligand, the chiral Pt metal ion, and the tetrapyridyltetraphenylethylene ligand is 1:4:1.

[0011] Preferably, the chiral Pt metal ion is a (R)-BINAP-based Pt metal ion with the following structural formula:

[0012] (IV).

[0013] Preferably, the chiral Pt metal ion is a (S)-BINAP-based Pt metal ion with the following structural formula:

[0014] (V).

[0015] Preferably, the specific process of self-assembly is as follows: the tetradentate sodium carboxylate organic ligand is mixed with chiral Pt metal ions and tetrapyridyltetraphenylethylene ligand in a container, a solvent is added, and the mixture is stirred for a set time to carry out self-assembly.

[0016] Preferably, the stirring temperature is 50°C and the stirring time is 14 hours.

[0017] Preferably, the solvent is a mixture of acetone and water.

[0018] Preferably, the self-assembled chiral metal cage complex further includes a post-processing step: removing the byproduct sodium trifluoromethanesulfonate, recrystallizing in diethyl ether, centrifuging and drying to obtain a precipitate, which is a powdered chiral metal cage complex.

[0019] A chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex prepared by any of the above preparation methods.

[0020] An application of the above-mentioned chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex, wherein the chiral metal cage complex is prepared as a chiral circularly polarized luminescent material.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a tetraphenylethylene supramolecular metal cage complex based on metal coordination. This method utilizes steric hindrance to transfer the chirality of the metal nodes to the tetraphenylethylene plane, and forms a helical structure on a larger scale through crystallization, thereby obtaining a high-performance circularly polarized luminescent material. By introducing a chiral binaphthyl group, the problem of excessive distance between the chiral unit and the luminescent unit is effectively solved. With the help of rigid metal coordination and steric effects, tetraphenylethylene is directionally induced to form a helical conformation, successfully preparing a single-chiral tetraphenylethylene molecule. Furthermore, the introduction of a sterically hindered chiral binaphthyl group into the metal cage improves the crystallization performance of the material, making single-crystal preparation simpler and more reliable. This method directly connects the chiral group to the metal node through covalent bonds and uses aggregation-induced emission molecules instead of traditional aggregation-induced quenching dyes to prepare a circularly polarized luminescent material with both a large luminescence asymmetry factor and high fluorescence quantum yield, expanding the application range of metal-organic cages.

[0022] This invention also discloses a chiral platinum-tetraphenylethylene supramolecular metal cage complex based on metal coordination. This complex covalently links chiral binaphthylene to platinum atoms and utilizes steric effects to achieve efficient chiral transfer to tetraphenylethylene, thereby obtaining a single-conformation tetraphenylethylene molecule. Benefiting from the aggregation-induced emission properties of tetraphenylethylene, this chiral metal cage forms a helical superstructure in the crystalline state, possessing both high fluorescence quantum yield and emission asymmetry factor, thus optimizing the performance of existing organic circularly polarized light-emitting materials. Attached Figure Description

[0023] Figure 1 This is a reaction route diagram of the present invention; Figure 2 The supramolecular metal cage-like complex obtained in Example 1 is a pure product. 1 H NMR spectrum; Figure 3 The supramolecular metal cage-like complex obtained in Example 1 is a pure product. 31 P NMR spectrum; Figure 4 The image shows the circularly polarized emission of the pure supramolecular metal cage complex obtained in Example 1. Figure 5 The image shows the circularly polarized emission of a microcrystalline suspension of the pure supramolecular metal cage complex obtained in Example 1. Figure 6 The single-crystal fluorescence quantum yield diagram of the supramolecular metal cage-like complex obtained in Example 1 is shown. Figure 7 The images show the circularly polarized emission patterns at different angles of the single-crystal wafer of the supramolecular metal cage complex obtained in Example 1. Figure 8 This is a single-crystal structure diagram of the supramolecular metal cage-like complex obtained in Example 1; Figure 9 The supramolecular metal cage-like complex obtained in Example 2 is a pure product. 1 H NMR spectrum; Figure 10 The supramolecular metal cage-like complex obtained in Example 2 is a pure product. 31 P NMR spectrum; Figure 11 The image shows the circularly polarized emission of the pure supramolecular metal cage complex obtained in Example 2. Figure 12 The image shows the circularly polarized emission of the microcrystalline suspension of the pure supramolecular metal cage complex obtained in Example 2. Figure 13 This is a single-crystal structure diagram of the supramolecular metal cage-like complex obtained in Example 2. Detailed Implementation

[0024] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0025] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0026] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0027] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0028] This embodiment discloses a chiral Pt metal-coordinated tetraphenylethylene supramolecular metal cage complex and its preparation method. The complex is obtained by self-assembly of a tetradentate sodium carboxylate ligand with a chiral Pt metal ion and a tetrapyridyltetraphenylethylene ligand. The structure of the tetradentate sodium carboxylate ligand used is as follows:

[0029] (I) The structural formula of the tetrapyridyltetraphenylethylene ligand is:

[0030] (II) The structural formula of the organoplatinum metal ion is:

[0031] (III) This invention discloses a method for preparing chiral supramolecular metal cage-like complexes based on metal coordination structures, as illustrated in the cartoon diagram below. Figure 1 As shown. The preparation method includes the following steps: 1) The tetradentate sodium carboxylate organic ligand, chiral Pt metal ions, and tetrapyridyltetraphenylethylene ligand were weighed and mixed in a strictly equivalent 1:4:1 molar ratio into a container. A mixed solvent of acetone and water (acetone:water = 4:1 v / v) was added, and the mixture was stirred at 50°C for 14 h. Due to the reversible dynamics of supramolecular chemistry, metal cages will form in the solution according to their content in a 1:4:1 ratio. After the removal of two trifluoromethanesulfonate ions, the organometallic platinum ions will self-assemble with one pyridine coordination site and one carboxylic acid coordination site through metal coordination bonds. Under the influence of the supramolecular compound's self-correcting properties (forming a minimal high-symmetry structure under the influence of the size effect), the target product will ultimately be formed.

[0032] 2) The solvent is evaporated under reduced pressure. The target metal cage complex is dissolved in acetonitrile and the insoluble byproduct sodium trifluoromethanesulfonate is filtered out. Then, an appropriate amount of diethyl ether is added to the solution for recrystallization to improve the purity of the product. The precipitate obtained after centrifugation and drying is the target chiral metal organic cage, which is easy to store.

[0033] In this process, a chiral organic binaphthyl ligand BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) is introduced via chiral Pt metal ions. Due to the presence of the organic binaphthyl ligand, the chiral Pt metal ion exhibits significant steric hindrance, making its molecular conformation less prone to rotation. Furthermore, its fully aromatic ring structure provides strong structural rigidity. Then, tetraphenylethylene and terphenyl ligands are linked into a metal-organic cage-like complex via O-Pt and N-Pt coordination bonds. The steric hindrance of the chiral binaphthyl ligand affects tetraphenylethylene, creating a chiral environment that directionally induces its conformation, resulting in the emission of circularly polarized light. Moreover, during recrystallization, the metal cage forms a helical structure on a larger scale, achieving a size effect in the chiral luminescence domain, thus yielding a high-performance circularly polarized luminescent material.

[0034] A second aspect of the present invention discloses a chiral supramolecular metal cage-like complex based on metal coordination structure, prepared by the above method. This complex is obtained by self-assembly of a tetradentate sodium carboxylate ligand with a chiral Pt metal ion and a tetrapyridyltetraphenylethylene ligand. The chiral Pt metal ion is bound to one pyridine coordination site and one carboxylic acid coordination site, respectively.

[0035] A third aspect of the present invention discloses an application of a chiral supramolecular metal cage complex based on metal coordination structure, wherein the chiral supramolecular metal cage complex based on metal coordination structure is used to prepare chiral circularly polarized luminescent materials.

[0036] 3) Dissolve 4 mg of chiral metal-organic cage in 1 mL of DMF solution, add 3 mL of 1,4-dioxane solution, and let stand for 8 h to obtain the corresponding microcrystalline suspension. Then, remove the supernatant by centrifugation multiple times and add 1,4-dioxane to finally obtain the chiral metal-organic cage microcrystalline suspension.

[0037] 4) Dissolve 3 mg of chiral metal-organic cage in 0.3 mL of DMF solution, and slowly diffuse 1,4-dioxane into the DMF solution by diffusion. After a set time (e.g., three weeks), large-size single crystals can be obtained.

[0038] The following analysis, combined with specific embodiments, provides further insights. Example 1: One-pot preparation of tetraphenylethylene supramolecular metal cage complex based on (R)-BINAP Pt metal coordination structure.

[0039] The chiral Pt nodes used are shown in the figure:

[0040] (IV) Weigh 1,4-bis(5-isophthaloyl)benzene (10.0 mg, 0.020 mmol, 1.0 equiv), (R)-BINAP bis(trifluoromethanesulfonic acid)platinum(II) (89.0 mg, 0.081 mmol, 4.0 equiv), and 1,1,2,2-tetratetra[4-(pyridin-4-yl)phenyl]ethylene (12.9 mg, 0.020 mmol, 1.0 equiv) all at once into a 20 mL glass bottle. Add water (1.5 mL) and acetone (6 mL) to the glass bottle, and stir overnight at 50 °C. The solvent was then removed by vacuum distillation, and the product was dissolved in acetonitrile (2 mL) and filtered. The filtrate was recrystallized in diethyl ether (8 mL), centrifuged, and the resulting product, a metallic cage, was dried to obtain a yellow solid. Yield: 87.3 mg (87%).

[0041] like Figure 2 , Figure 3 As shown, by 1 H NMR and 31 P NMR data jointly confirmed the acquisition of the pure metal cage product. 1 The integration ratio in H NMR is correct. 31The ddd peaks in the P NMR splitting indicate that the two P atoms on the organometallic platinum ligand are in different chemical environments, consistent with the expected configuration of the metal cage. Figure 4 As shown, the metal cage is in methanol:glycerol = 3:2 (v / v, c = 10 µM, λ) ex The test results of circularly polarized light in a mixed solvent (340 nm) showed a clear right-handed circularly polarized light signal.

[0042] Dissolve 4 mg of the above-mentioned metal cage in 1 mL of DMF solution in a 4 mL glass bottle, and add 3 mL of 1,4-dioxane solution to the 4 mL glass bottle. Let it stand for 8 h, pour the suspension into a 10 mL centrifuge tube, centrifuge at 8000 rpm for 30 s, discard the supernatant, and add 1,4-dioxane again to the 10 mL centrifuge tube to finally obtain a chiral metal-organic cage microcrystal suspension. Figure 5 As shown, metal cage microcrystals in a suspension of 1,4-dioxane (λ) ex The circularly polarized light test results at 340 nm showed a significant right-handed circularly polarized light signal, which was amplified by approximately 16 times compared to the solution system. 3 mg of the aforementioned metal cage was added to a 4 mL glass vial, followed by 0.3 mL of DMF solution. 8 mL of 1,4-dioxane was added to a 20 mL glass vial. The 4 mL vial cap was loosely closed, and the 20 mL vial cap was tightened. Large-size single crystals were obtained by allowing the solution to slowly evaporate. Figure 7 As shown, a large single crystal was encapsulated onto a quartz plate using single crystal protective oil. Its circularly polarized luminescence was measured every 30°. The average luminescence was... g lum The value is 0.12, and the resulting single-crystal structure is shown in the figure. Figure 8 As shown, the green structure is a tetrapyridyltetraphenylethylene ligand, the blue structure is a tetradentate sodium carboxylate ligand, the white structure is a chiral binaphthalene and phenylphosphine ligand, and the red structure is a chiral Pt metal ion.

[0043] Example 2: One-pot preparation of tetraphenylethylene supramolecular metal cage complexes based on Pt metal coordination of (S)-BINAP The chiral Pt nodes used are shown in the figure:

[0044] (V) Weigh 1,4-bis(5-isophthaloyl)benzene (10.0 mg, 0.020 mmol, 1.0 equiv), (S)-BINAP bis(trifluoromethanesulfonic acid)platinum(II) (89.0 mg, 0.081 mmol, 4.0 equiv), and 1,1,2,2-tetratetra[4-(pyridin-4-yl)phenyl]ethylene (12.9 mg, 0.020 mmol, 1.0 equiv) all at once into a 20 mL glass bottle. Add water (1.5 mL) and acetone (6 mL) to the glass bottle, and stir overnight at 50 °C. The solvent was then removed by vacuum distillation, and the product was dissolved in acetonitrile (2 mL) and filtered. The filtrate was recrystallized in diethyl ether (8 mL), centrifuged, and the resulting product, a metallic cage, was dried to obtain a yellow solid. Yield: 88.4 mg (89%).

[0045] like Figure 9 , Figure 10 As shown, by 1 H NMR and 31 P NMR data jointly confirmed the acquisition of the pure metal cage product. 1 The integration ratio in H NMR is correct. 31 The ddd peaks in the P NMR splitting indicate that the two P atoms on the organometallic platinum ligand are in different chemical environments, consistent with the expected configuration of the metal cage. Figure 11 As shown, the metal cage is in methanol:glycerol = 3:2 (v / v, c = 10 µM, λ) ex The test results of circularly polarized light in a mixed solvent (340 nm) showed a clear right-handed circularly polarized light signal.

[0046] Dissolve 4 mg of the above-mentioned metal cage in 1 mL of DMF solution in a 4 mL glass bottle, and add 3 mL of 1,4-dioxane solution to the 4 mL glass bottle. Let it stand for 8 hours, pour the suspension into a 10 mL centrifuge tube, centrifuge at 8000 rpm for 30 seconds, discard the supernatant, and add 1,4-dioxane to the 10 mL centrifuge tube again. Repeat the above process 3 times to finally obtain a chiral metal-organic cage microcrystal suspension. Figure 12 As shown, metal cage microcrystals in a suspension of 1,4-dioxane (λ) ex The circularly polarized light test results at 340 nm showed a significant right-handed circularly polarized light signal, which was amplified by approximately 16 times compared to the solution system. 3 mg of the aforementioned metal cage was added to a 4 mL glass vial, followed by 0.3 mL of DMF solution. 8 mL of 1,4-dioxane was added to a 20 mL glass vial. The 4 mL vial cap was loosely closed, and the 20 mL vial cap was tightened. Large-size single crystals were obtained by allowing slow evaporation. Figure 13The structure represents the single crystal structure of the metal cage described above. The green structure is a tetrapyridyltetraphenylethylene ligand, the blue structure is a tetradentate sodium carboxylate ligand, the white structure is a chiral binaphthalene and phenylphosphine ligand, and the red structure is a chiral Pt metal ion.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex, characterized in that, The tetraphenylethylene chiral metal cage complex is obtained by self-assembly of a tetradentate sodium carboxylate ligand, a chiral Pt metal ion, and a tetrapyridyl tetraphenylethylene ligand. During the self-assembly process, the chiral Pt metal ion removes two trifluoromethanesulfonate groups and then binds to a pyridine coordination site and a carboxylic acid coordination site. The tetradentate sodium carboxylate ligand has the following structural formula: （I） The structural formula of the tetrapyridyltetraphenylethylene ligand is: (II) The structural formula of the chiral Pt metal ion is: (III).

2. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 1, characterized in that, The molar ratio of the tetradentate sodium carboxylate organic ligand, the chiral Pt metal ion, and the tetrapyridyltetraphenylethylene ligand is 1:4:

1.

3. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 1, characterized in that, The chiral Pt metal ion is a Pt metal ion based on (R)-BINAP, with the following structural formula: (IV).

4. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 1, characterized in that, The chiral Pt metal ion is a (S)-BINAP-based Pt metal ion with the following structural formula: （V）。 5. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 1, characterized in that, The specific process of self-assembly is as follows: the tetradentate sodium carboxylate organic ligand is mixed with chiral Pt metal ions and tetrapyridyltetraphenylethylene ligand in a container, a solvent is added, and the mixture is stirred for a set time to carry out self-assembly.

6. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 5, characterized in that, The stirring temperature is 50℃ and the stirring time is 14h.

7. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 5, characterized in that, The solvent is a mixture of acetone and water.

8. The method for preparing a chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex according to claim 1, characterized in that, The self-assembled chiral metal cage complex also includes a post-processing procedure: removing the byproduct sodium trifluoromethanesulfonate, recrystallizing in diethyl ether, centrifuging and drying to obtain a precipitate, which is a powdered chiral metal cage complex.

9. A chiral Pt metal-coordinated tetraphenylethylene chiral metal cage complex prepared by any one of the preparation methods of claims 1-8.

10. An application of the tetraphenylethylene chiral metal cage complex based on chiral Pt metal coordination as described in claim 9, characterized in that, The chiral metal cage complex was prepared into a chiral circularly polarized luminescent material.

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