A circularly polarized room-temperature phosphorescent organic eutectic, its preparation method and application

Abstract

This invention discloses a circularly polarized room-temperature phosphorescent organic cocrystal, its preparation method, and its applications. The organic cocrystal is formed by the self-assembly of chiral donor and acceptor molecules. The chiral donor molecule is S / R-1-(1-naphthyl)ethanol, and the acceptor molecule is 1,2,4,5-benzenetetracarbonyl nitrile. The levorotatory or dextrorotatory chiral donor and acceptor molecules are dissolved in a good solvent, then a poor solvent is added. The mixture is sonicated until completely dissolved and allowed to stand until the solvent completely evaporates, yielding the organic cocrystal. Both the levorotatory and dextrorotatory chiral cocrystals exhibit green phosphorescence emission upon excitation. The lifetime of the levorotatory chiral cocrystal is 24.91 ms, and that of the dextrorotatory chiral cocrystal is 28.48 ms. The cocrystals exhibit excellent circularly polarized room-temperature phosphorescence performance, with the levorotatory chiral cocrystal achieving a phosphorescence efficiency of 22.43% per g. lum | is 0.03. The phosphorescence efficiency of the dextrorotatory chiral eutectic is 30.97%, | g lum | is 0.065.

Description

Technical Field

[0001] This invention relates to the field of organic eutectic growth and preparation technology, and in particular to a circularly polarized room temperature phosphorescent organic eutectic, its preparation method, and its application. Background Technology

[0002] In recent years, circularly polarized light has attracted widespread attention due to its applications in 3D displays, optical sensors, anti-counterfeiting encryption, and asymmetric catalysis. Traditionally, circularly polarized light can be generated from unpolarized light using physical methods. The emitted unpolarized light is first converted into linearly polarized light by a linear polarizer, and then further decomposed into left- or right-handed polarized light by a quarter-wave plate. However, in this physical process, the light wave loses at least 50% of its energy. Chiral molecules, due to their non-mirror-overlapping geometry, often exhibit unique photophysical properties, such as circular dichroism (CD) and circularly polarized luminescence (CPL). Chiral luminescent molecules can directly generate circularly polarized light through excitation without relying on a polarizer. Compared to traditional methods, this significantly reduces energy loss and has greater application potential.

[0003] Organic room-temperature phosphorescent materials have wide applications in anti-counterfeiting encryption, biophysical therapy, and other fields due to their long luminescence lifetime and ease of modification. Compared with circularly polarized fluorescent materials, research on circularly polarized room-temperature phosphorescent materials is relatively limited. This is mainly because the current main method for synthesizing circularly polarized room-temperature phosphorescent materials is to link chiral molecules and room-temperature phosphorescent molecules through covalent bonds. However, this method often alters the structure and interactions of room-temperature phosphorescent molecules, causing the highly sensitive triplet excitons to become inactive, thus preventing the generation of circularly polarized room-temperature phosphorescence.

[0004] Organic eutectic is a crystalline solid composed of two or more molecules in a stoichiometric ratio, formed through non-covalent bonding. In recent years, eutectic engineering, as a novel material preparation strategy, has gained widespread attention in the field of optoelectronics due to its simplicity and tunable properties. Specifically, by flexibly selecting suitable chiral donor and acceptor materials, circularly polarized luminescent materials with various properties can be prepared. Furthermore, the ordered molecular stacking and strong intermolecular interactions in organic eutectic restrict molecular rotation and vibration, suppressing nonradiative transitions of triplet excitons, which is beneficial for achieving circularly polarized room-temperature phosphorescence. Summary of the Invention

[0005] The purpose of this invention is to address the technical shortcomings of existing technologies, such as the difficulty in preparing circularly polarized room-temperature phosphorescent materials, by providing a circularly polarized room-temperature phosphorescent organic eutectic and its preparation method.

[0006] Another object of the present invention is to provide the application of the circularly polarized room temperature phosphorescent organic eutectic.

[0007] The technical solution adopted to achieve the purpose of this invention is:

[0008] A circularly polarized room-temperature phosphorescent organic eutectic is formed by the self-assembly of a chiral donor molecule and an acceptor molecule, wherein the chiral donor molecule is S-1-(1-naphthyl)ethanol or R-1-(1-naphthyl)ethanol, and the acceptor molecule is 1,2,4,5-benzenetetracarbonitrile.

[0009] The structural formula of the chiral donor molecule is:

[0010]

[0011] The molecular structure of the receptor molecule is as follows:

[0012]

[0013] In the above technical solution, the molar ratio of S-1-(1-naphthyl)ethanol or R-1-(1-naphthyl)ethanol to 1,2,4,5-benzenetetracarbonyl nitrile is 1:1.

[0014] In the above technical solution, when the chiral donor is S-1-(1-naphthyl)ethanol, the circularly polarized room temperature phosphorescent organic eutectic is a left-handed chiral eutectic, which is a monoclinic crystal system with space group P21.

[0015] In the above technical solution, the cell parameters of the left-handed chiral eutectic are: α=90°, β=98.262°, γ=90°.

[0016] In the above technical solution, when the chiral donor is R-1-(1-naphthyl)ethanol, the circularly polarized room temperature phosphorescent organic eutectic is a dextrorotatory chiral eutectic, which is an orthorhombic crystal system with space group P212121.

[0017] In the above technical solution, the cell parameters of the right-handed chiral eutectic are: α = β = γ = 90°.

[0018] In the above technical solution, the preparation method of the circularly polarized room temperature phosphorescent organic eutectic includes the following steps:

[0019] The levorotatory or dextrorotatory chiral donor and acceptor molecules are dissolved in a good solvent, then a poor solvent is added. The mixture is sonicated until completely dissolved and allowed to stand until the solvent has completely evaporated, yielding the organic cocrystal. The circularly polarized room-temperature phosphorescent organic cocrystal is primarily formed through self-assembly driven by charge transfer interactions and hydrogen bonding between the donor and acceptor molecules. The introduction of 1,2,4,5-benzenetetracarbonyl nitrile alters the interactions between chiral molecules, stabilizing the triplet exciton. Simultaneously, the chiral donor material imparts supramolecular chirality to the organic cocrystal through chiral induction, resulting in its circularly polarized room-temperature phosphorescent properties.

[0020] In the above technical solution, the good solvent is dichloromethane, trichloromethane or tetrahydrofuran, the bad solvent is n-hexane or cyclohexane, and the volume ratio of the good solvent to the bad solvent is 4:1 to 2:1.

[0021] In the above technical solution, the solvent evaporation temperature is 25-35℃.

[0022] Another aspect of the present invention includes the potential application of the circularly polarized room-temperature phosphorescent organic eutectic in fields such as anti-counterfeiting and encryption. By filtering the corresponding circularly polarized light with left-handed or right-handed filters, selective display of the organic eutectic luminescence can be achieved, thereby enabling its application in anti-counterfeiting and encryption.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. Both the left-handed and right-handed chiral eutectic of this invention exhibit green phosphorescence emission under excitation, with a lifetime of 24.91 ms for the left-handed chiral eutectic and 28.48 ms for the right-handed chiral eutectic. Both exhibit excellent circularly polarized room-temperature phosphorescence performance, with the left-handed chiral eutectic achieving a phosphorescence efficiency of 22.43% |g lum | is 0.03. The phosphorescence efficiency of the dextrorotatory chiral eutectic is 30.97%, | g lum The value is 0.065, which is a significant improvement compared to chiral donor molecules.

[0025] 2. The organic eutectic of the present invention has a well-defined crystal structure, providing a good platform for revealing the relationship between structure and performance, and paving the way for the further preparation of high-performance circularly polarized room temperature phosphorescent materials. Attached Figure Description

[0026] Figure 1 This is an optical microscope image of the left-handed chiral eutectic obtained in Example 1.

[0027] Figure 2 This is a fluorescence microscope image of the left-handed chiral eutectic obtained in Example 1.

[0028] Figure 3The crystal structure of the left-handed chiral eutectic obtained in Example 1 is shown.

[0029] Figure 4 This is an optical microscope image of the right-handed chiral eutectic obtained in Example 2.

[0030] Figure 5 This is a fluorescence microscope image of the dextrorotatory chiral eutectic obtained in Example 2.

[0031] Figure 6 The crystal structure of the right-handed chiral eutectic obtained in Example 2 is shown.

[0032] Figure 7 The fluorescence spectrum of the left-handed chiral eutectic obtained in Example 1 is shown.

[0033] Figure 8 The image shows the luminescence lifetime of the left-handed chiral eutectic obtained in Example 1.

[0034] Figure 9 The fluorescence spectrum of the dextrorotatory chiral eutectic obtained in Example 2 is shown.

[0035] Figure 10 The image shows the luminescence lifetime of the right-handed chiral eutectic obtained in Example 2.

[0036] Figure 11 The CD spectra of the left-handed and right-handed chiral eutectics and the corresponding chiral donor crystals obtained in Examples 1 and 2 are shown.

[0037] Figure 12 The CPL spectra of the left-handed and right-handed chiral eutectics and the corresponding chiral donor crystals obtained in Examples 1 and 2 are shown.

[0038] Figure 13 The phosphorescence efficiency and |g of the left-handed and right-handed chiral eutectics obtained in Examples 1 and 2 with the corresponding chiral donor crystals are shown. lum | Comparison chart. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0040] Example 1

[0041] A circularly polarized room-temperature phosphorescent organic eutectic (left-handed chiral eutectic, denoted as S-Cocrystal) is prepared by the following steps:

[0042] S-1-(1-naphthyl)ethanol and 1,2,4,5-benzenetetracarbonyl nitrile were placed in a 10 mL glass bottle at a molar ratio of 1:1. 3 mL of dichloromethane and 1 mL of n-hexane were added, and the mixture was sonicated until the solutes were completely dissolved. The glass bottle was then placed open on a stable surface and allowed to stand for 3-5 days to evaporate. The resulting yellow-green crystals are the levorotatory chiral eutectic.

[0043] Optical microscope images of the circularly polarized room-temperature phosphorescent organic eutectic prepared in Example 1 are shown below. Figure 1 As shown, Figure 2 The image shows a fluorescence microscope image of the organic eutectic. As can be seen, the levorotatory chiral eutectic exhibits a green luminescence color. The detailed crystal structure and packing configuration of this eutectic are shown below. Figure 3 As shown, the organic eutectic is a monoclinic crystal system, space group P21, with cell parameters a = 7.00690 (10). b = 7.6255(2) c = 16.5935(3) α=90°, β=98.262°, γ=90°.

[0044] Example 2

[0045] A circularly polarized room-temperature phosphorescent organic eutectic (dextral chiral eutectic, denoted as R-Cocrystal) is prepared by the following steps:

[0046] R-1-(1-naphthyl)ethanol and 1,2,4,5-benzenetetracarbonyl nitrile were placed in a 10 mL glass bottle at a molar ratio of 1:1. 3 mL of dichloromethane and 1 mL of n-hexane were added, and the mixture was sonicated until the solutes were completely dissolved. The glass bottle was then placed open on a stable surface and allowed to stand for 3-5 days to evaporate. The resulting yellow-green crystals are the dextrorotatory chiral eutectic.

[0047] Optical microscope images of the circularly polarized room-temperature phosphorescent organic eutectic prepared in Example 2 are shown below. Figure 4 As shown, Figure 5 The fluorescence micrograph of this organic eutectic shows that the levorotatory chiral eutectic exhibits a green luminescence. The detailed crystal structure and packing configuration of this eutectic are shown below. Figure 6 As shown, the organic eutectic is a monoclinic crystal system, space group P212121, with a cell parameter of a = 7.07250 (10). b = 7.60540(10) c = 32.2517(5) α = β = γ = 90°.

[0048] Example 3

[0049] Steady-state and transient fluorescence spectroscopy tests were performed on the left-handed and right-handed chiral eutectics obtained in Examples 1 and 2. Figure 7The fluorescence spectrum of the levorotatory chiral eutectic is shown. Figure 8 The image shows the emission lifetime of the left-handed chiral eutectic at 520 nm, with a lifetime of 24.91 ms. Figure 9 The fluorescence spectrum of the dextrorotatory chiral eutectic is shown. Figure 10 The image shows the emission lifetime of the right-handed chiral eutectic at 508 nm, with a lifetime of 28.48 ms.

[0050] Comparative Example 1

[0051] The steps for preparing chiral donor crystals are as follows:

[0052] S-1-(1-naphthyl)ethanol and 1,2,4,5-benzenetetracarbonyl nitrile were placed in a 10 mL glass bottle at a molar ratio of 1:1. 3 mL of dichloromethane and 1 mL of n-hexane were added, and the mixture was sonicated until the solute was completely dissolved. The bottle was then placed open on a stable surface and allowed to evaporate for 3-5 days. The resulting yellow-green crystals are the levorotatory donor crystals, denoted as S-Cocrystal. Replacing S-1-(1-naphthyl)ethanol with R-1-(1-naphthyl)ethanol under the same conditions yields the dextrorotatory donor crystals, denoted as R-Cocrystal.

[0053] Figure 11 For the comparison of the CD spectra of chiral donor crystals and chiral eutectics, from Figure 11 It can be seen that after the formation of the eutectic, the CD signal shows a significant red shift and the intensity is significantly improved.

[0054] Figure 12 For the comparison of CPL spectra of chiral donor crystals and chiral eutectics, from Figure 12 It can be seen that after the formation of the eutectic, the CPL signal exhibits a significant red shift and the intensity is significantly improved.

[0055] Figure 13 Phosphorescence efficiency and |g of chiral donor crystals and chiral eutectic crystals lum Numerical comparisons show that the performance of chiral eutectic is significantly improved compared to chiral donor crystals. The phosphorescence efficiency of the left-handed chiral eutectic reaches 22.43%, |g lum | is 0.03. The phosphorescence efficiency of the dextrorotatory chiral eutectic is 30.97%, | g lum The value is 0.065.

[0056] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A circularly polarized room-temperature phosphorescent organic eutectic, characterized in that, The organic cocrystal is formed by the self-assembly of a chiral donor molecule and an acceptor molecule, wherein the chiral donor molecule is S-1-(1-naphthyl)ethanol or R-1-(1-naphthyl)ethanol, and the acceptor molecule is 1,2,4,5-benzenetetracarbonitrile. The molar ratio of S-1-(1-naphthyl)ethanol or R-1-(1-naphthyl)ethanol to 1,2,4,5-benzenetetracarbonyl is 1:

1. When the chiral donor molecule is S-1-(1-naphthyl)ethanol, the circularly polarized room-temperature phosphorescent organic eutectic is a levorotatory chiral eutectic, and the levorotatory chiral eutectic is a monoclinic crystal system. P Space group 21, the cell parameters of the left-handed chiral eutectic are: a=7.00690(10)Å, b=7.6255(2)Å, c=16.5935(3)Å, α=90º, β=98.262º, γ=90º; When the chiral donor molecule is R-1-(1-naphthyl)ethanol, the circularly polarized room-temperature phosphorescent organic eutectic is a dextrorotatory chiral eutectic, and the dextrorotatory chiral eutectic is orthorhombic. P Space group 212121, the cell parameters of the right-handed chiral eutectic are: a=7.07250(10)Å, b=7.60540(10)Å, c=32.2517(5)Å, α=β=γ=90º.

2. The method for preparing circularly polarized room-temperature phosphorescent organic eutectic as described in claim 1, characterized in that, Includes the following steps: Chiral donor and acceptor molecules are dissolved in a good solvent, then a poor solvent is added, and the mixture is sonicated until completely dissolved. After standing, the solvent is allowed to evaporate completely to obtain the organic eutectic.

3. The preparation method according to claim 2, characterized in that, The good solvent is dichloromethane, trichloromethane, or tetrahydrofuran, and the bad solvent is n-hexane or cyclohexane. The volume ratio of the good solvent to the bad solvent is 4:1 to 2:

1.

4. The preparation method according to claim 2, characterized in that, The solvent evaporates at a temperature of 25-35℃.

5. The application of circularly polarized room-temperature phosphorescent organic eutectic as described in claim 1 in anti-counterfeiting encryption.

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