Circularly-polarized room-temperature phosphorescent organic eutectic and preparation method and application thereof

Abstract

The invention discloses a circularly polarized room temperature phosphorescent organic eutectic and a preparation method and application thereof, the organic eutectic is formed by self-assembling a chiral donor molecule and an acceptor molecule, the chiral donor molecule is S / R-1-(1-naphthyl) ethanol, and the acceptor molecule is 1, 2, 4, 5-benzene tetraformonitrile. The preparation method comprises the following steps: dissolving levorotatory or dextrorotatory chiral donor molecules and acceptor molecules in a good solvent, then adding a poor solvent, carrying out ultrasonic treatment until the molecules are completely dissolved, standing, and after the solvent is completely volatilized, obtaining the organic eutectic crystal. The left-handed chiral eutectic and the right-handed chiral eutectic both present green phosphorescence emission under excitation, the service life of the left-handed chiral eutectic is 24.91 ms, and the service life of the right-handed chiral eutectic is 28.48 ms. The co-crystal shows excellent circular polarization room temperature phosphorescence performance, the phosphorescence efficiency of the L-chiral co-crystal reaches 22.43%, and the glum is 0.03. The phosphorescence efficiency of the right-handed chiral eutectic crystal is 30.97%, and the glum is 0.065.

Description

Technical Field

[0001] The invention relates to the technical field of organic eutectic growth and preparation, and in particular to a circularly polarized room temperature phosphorescent organic eutectic and a preparation method and application thereof. Background Art

[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 by physical methods. The emitted unpolarized light is first converted into linearly polarized light by a linear polarizer, and then further decomposed into left-handed 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 usually exhibit unique photophysical properties such as circular dichroism (CD) and circularly polarized luminescence (CPL) due to their geometric properties that cannot overlap with mirror images. Chiral luminescent molecules can directly generate circularly polarized light through excitation without relying on polarizers. Compared with traditional methods, this significantly reduces energy loss and has greater application potential.

[0003] Organic room temperature phosphorescent materials are widely used in anti-counterfeiting encryption, biotherapy, etc. due to their long luminescence lifetime and easy modification. Compared with circularly polarized fluorescent materials, research on circularly polarized room temperature phosphorescent materials is relatively less, mainly because the main method for synthesizing circularly polarized room temperature phosphorescent materials is to connect chiral molecules and room temperature phosphorescent molecules through covalent bonds, but this method often changes the structure and interaction of room temperature phosphorescent molecules, making the highly sensitive triplet excitons inactive and unable to produce circularly polarized room temperature phosphorescence.

[0004] Organic eutectics are crystalline single solids of a certain stoichiometric ratio formed by two or more molecules through non-covalent bonding. In recent years, eutectic engineering, as a new material preparation strategy, has gained wide attention in the field of optoelectronics due to its simple preparation and adjustable properties. Among them, circularly polarized luminescent materials with various properties can be prepared by flexibly selecting suitable chiral donor and acceptor materials. In addition, the orderly molecular stacking and strong intermolecular interactions of organic eutectics restrict the rotation and vibration of molecules, inhibit the non-radiative transition of triplet excitons, and are conducive to the realization of circularly polarized room temperature phosphorescence. Summary of the invention

[0005] The purpose of the present invention is to provide a circularly polarized room temperature phosphorescent organic eutectic and a preparation method thereof in view of the technical defect that the circularly polarized room temperature phosphorescent material is difficult to prepare in the prior art.

[0006] Another object of the present invention is to provide applications of the circularly polarized room temperature phosphorescent organic co-crystal.

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

[0008] A circularly polarized room temperature phosphorescent organic eutectic is formed by 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 structural formula of the receptor molecule is:

[0012]

[0013] In the above technical solution, the molar ratio of the S-1-(1-naphthyl)ethanol or R-1-(1-naphthyl)ethanol and 1,2,4,5-benzenetetracarbonitrile 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, and the left-handed chiral eutectic is a monoclinic system with a P21 space group.

[0015] In the above technical solution, the unit 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 right-handed chiral eutectic, and the right-handed chiral eutectic is an orthorhombic crystal system with a space group of P212121.

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

[0018] In the above technical solution, the method for preparing the circularly polarized room temperature phosphorescent organic eutectic comprises the following steps:

[0019] The left-handed or right-handed chiral donor molecule and acceptor molecule are dissolved in a good solvent, and then a poor solvent is added. After being completely dissolved by ultrasonic treatment, the organic co-crystal is allowed to stand. After the solvent is completely volatilized, the organic co-crystal is obtained. The circularly polarized room temperature phosphorescent organic co-crystal is mainly driven by the charge transfer interaction and hydrogen bond interaction between the donor and the acceptor, and the co-crystal is prepared by self-assembly. The introduction of 1,2,4,5-benzenetetracarbonitrile changes the interaction between chiral molecules and stabilizes the triplet excitons. At the same time, the chiral donor material imparts supramolecular chirality to the organic co-crystal through chiral induction, so that it exhibits circularly polarized room temperature phosphorescent characteristics.

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

[0021] In the above technical solution, the temperature at which the solvent evaporates is 25-35°C.

[0022] Another aspect of the present invention is that the circularly polarized room temperature phosphorescent organic eutectic has potential applications in the fields of anti-counterfeiting and encryption. The corresponding circularly polarized light is filtered by a left-handed or right-handed filter to achieve selective display of the luminescence of the organic eutectic, so that it can be applied to anti-counterfeiting and encryption.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The left-handed chiral eutectic and the right-handed chiral eutectic of the present invention both exhibit green phosphorescence emission under excitation, the lifetime of the left-handed chiral eutectic is 24.91ms, and the lifetime of the right-handed chiral eutectic is 28.48ms. Both the left-handed chiral eutectic and the right-handed chiral eutectic exhibit excellent circularly polarized room temperature phosphorescence performance, and the phosphorescence efficiency of the left-handed chiral eutectic reaches 22.43%, |g lum | is 0.03. The phosphorescence efficiency of the right-handed chiral eutectic is 30.97%, |g lum | is 0.065. Compared with the chiral donor molecule, it has been significantly improved.

[0025] 2. The organic eutectic of the present invention has a clear crystal structure, which provides a good platform for revealing the relationship between structure and performance, and broadens the way for further preparing high-performance circularly polarized room temperature phosphorescent materials. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

[0030] Figure 5 This is a fluorescence microscope photograph of the right-handed chiral eutectic obtained in Example 2.

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

[0032] Figure 7 This is the fluorescence spectrum of the left-handed chiral co-crystal obtained in Example 1.

[0033] Figure 8 This is the luminescence lifetime diagram of the left-handed chiral eutectic obtained in Example 1.

[0034] Fig. 9 This is the fluorescence spectrum of the right-handed chiral co-crystal obtained in Example 2.

[0035] Fig.10 This is the luminescence lifetime diagram of the right-handed chiral eutectic obtained in Example 2.

[0036] Fig.11 CD spectra of the left-handed and right-handed chiral co-crystals obtained in Example 1 and Example 2 and the corresponding chiral donor crystals.

[0037] Fig.12 CPL spectra of the left-handed and right-handed chiral co-crystals obtained in Example 1 and Example 2 and the corresponding chiral donor crystals.

[0038] Fig.13 The phosphorescence efficiency and g of the left-handed and right-handed chiral co-crystals obtained in Example 1 and Example 2 and the corresponding chiral donor crystals are shown in Table 1. lum |Comparison chart. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] Example 1

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

[0042] Place S-1-(1-naphthyl)ethanol and 1,2,4,5-benzene tetracarbonitrile in a 10 mL glass bottle at a molar ratio of 1:1, add 3 mL of dichloromethane and 1 mL of n-hexane, and sonicate until the solute is completely dissolved. Place the open glass bottle on a stable table and let it stand for 3-5 days to evaporate. The yellow-green crystals obtained are the left-handed chiral eutectic.

[0043] The optical microscope photo of the circularly polarized room temperature phosphorescent organic eutectic prepared in Example 1 is as follows: Figure 1 As shown, Figure 2 This is a fluorescence microscope photo of the organic co-crystal. It can be seen from the figure that the left-handed chiral co-crystal exhibits a green luminescent color. The detailed crystal structure and stacking form of the co-crystal are shown in Figure 3 As shown, the organic eutectic is a monoclinic system, P21 space group, and the unit cell parameter is: 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 cocrystal (right-handed chiral cocrystal, denoted as R-Cocrystal) is prepared by the following steps:

[0046] Place R-1-(1-naphthyl)ethanol and 1,2,4,5-benzene tetracarbonitrile in a 10 mL glass bottle at a molar ratio of 1:1, add 3 mL of dichloromethane and 1 mL of n-hexane, and sonicate until the solute is completely dissolved. Place the open glass bottle on a stable table and let it stand for 3-5 days to evaporate. The yellow-green crystals obtained are right-handed chiral eutectics.

[0047] The optical microscope photo of the circularly polarized room temperature phosphorescent organic eutectic prepared in Example 2 is as follows: Figure 4 As shown, Figure 5 This is a fluorescence microscope photo of the organic co-crystal. It can be seen that the left-handed chiral co-crystal emits green light. The detailed crystal structure and stacking form of the co-crystal are shown in Figure 2. Figure 6 As shown, the organic eutectic is a monoclinic system with a space group of P212121 and a unit cell parameter of a=7.07250(10) b=7.60540(10) c=32.2517(5) α=β=γ=90°.

[0048] Example 3

[0049] The left-handed chiral co-crystal and the right-handed chiral co-crystal obtained in Example 1 and Example 2 were subjected to steady-state / transient fluorescence spectroscopy tests. Figure 7is the fluorescence spectrum of left-handed chiral eutectic. Figure 8 This is the luminescence lifetime diagram of the left-handed chiral eutectic at 520nm, and its lifetime is 24.91ms. Fig. 9 is the fluorescence spectrum of right-handed chiral eutectic. Fig.10 This is the luminescence lifetime diagram of the right-handed chiral eutectic at 508nm, and its lifetime is 28.48ms.

[0050] Comparative Example 1

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

[0052] Place S-1-(1-naphthyl)ethanol and 1,2,4,5-benzene tetracarbonitrile in a 10 mL glass bottle at a molar ratio of 1:1, add 3 mL of dichloromethane and 1 mL of n-hexane, and sonicate until the solute is completely dissolved. Place the open glass bottle on a stable table and let it stand for 3-5 days to evaporate. The yellow-green crystals obtained are left-handed donor crystals, recorded as S-Cocrystal. Replacing S-1-(1-naphthyl)ethanol with R-1-(1-naphthyl)ethanol can prepare right-handed donor crystals under the same conditions, recorded as R-Cocrystal.

[0053] Fig.11 CD spectra comparison of chiral donor crystal and chiral eutectic. Fig.11 It can be seen that after the formation of eutectic, its CD signal shows an obvious red shift and the intensity is significantly increased.

[0054] Fig.12 The CPL spectra of the chiral donor crystal and the chiral eutectic are compared. Fig.12 It can be seen that after the formation of eutectic, its CPL signal shows an obvious red shift and the intensity is significantly increased.

[0055] Fig.13 is the phosphorescence efficiency and |g of the chiral donor crystal and chiral eutectic lum | Numerical comparison shows that the performance of chiral eutectic is significantly improved compared with chiral donor crystal. The phosphorescence efficiency of left-handed chiral eutectic reaches 22.43%, |g lum | is 0.03. The phosphorescence efficiency of the right-handed chiral eutectic is 30.97%, |g lum | is 0.065.

[0056] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A circularly polarized room temperature phosphorescent organic eutectic, characterized in that: The organic co-crystal is formed by 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.

2. The circularly polarized room temperature phosphorescent organic eutectic according to claim 1, characterized in that: The molar ratio of the S-1-(1-naphthyl)ethanol or R-1-(1-naphthyl)ethanol to 1,2,4,5-benzenetetracarbonitrile is 1:

1.

3. The circularly polarized room temperature phosphorescent organic eutectic according to claim 1, characterized in that: When the chiral donor molecule is S-1-(1-naphthyl)ethanol, the circularly polarized room temperature phosphorescent organic cocrystal is a left-handed chiral cocrystal, and the left-handed chiral cocrystal is a monoclinic crystal system with a P21 space group.

4. The circularly polarized room temperature phosphorescent organic eutectic according to claim 3, characterized in that: The unit cell parameters of the left-handed chiral eutectic are: α=90°, β=98.262°, γ=90°.

5. The circularly polarized room temperature phosphorescent organic eutectic according to claim 1, characterized in that: When the chiral donor molecule is R-1-(1-naphthyl)ethanol, the circularly polarized room temperature phosphorescent organic cocrystal is a right-handed chiral cocrystal, and the right-handed chiral cocrystal is an orthorhombic crystal system with a space group of P212121.

6. The circularly polarized room temperature phosphorescent organic eutectic according to claim 5, characterized in that: The unit cell parameters of the right-handed chiral eutectic are: α=β=γ=90°.

7. The method for preparing a circularly polarized room temperature phosphorescent organic eutectic according to claim 1, characterized in that: The following steps are involved: The chiral donor molecule and the acceptor molecule are dissolved in a good solvent, and then a poor solvent is added, and the mixture is ultrasonicated until the mixture is completely dissolved, and then allowed to stand, and after the solvent is completely evaporated, the organic co-crystal is obtained.

8. The preparation method according to claim 7, characterized in that: The good solvent is dichloromethane, chloroform or tetrahydrofuran, the poor solvent is n-hexane or cyclohexane, and the volume ratio of the good solvent to the poor solvent is 4:1 to 2:

1.

9. The preparation method according to claim 7, characterized in that: The temperature at which the solvent evaporates is 25-35°C.

10. Use of the circularly polarized room temperature phosphorescent organic eutectic as claimed in claim 1 in anti-counterfeiting encryption.

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