An exciplex type circularly polarized luminescent material and a preparation method thereof

Abstract

The application discloses an excimer type circularly polarized luminescent material and a preparation method thereof. The excimer type circularly polarized luminescent material is composed of a pair of chiral excimer donor and acceptor molecules. The donor is a molecule DMG prepared by covalently connecting N, N-dimethylaniline as a head group with a chiral glutamine derivative through an amide bond. The acceptor is a molecule PG prepared by covalently connecting pyrene as a head group with a chiral glutamine derivative through an amide bond. The application covalently connects a pair of classic excimer N, N-dimethylaniline and pyrene with a long-chain chiral glutamine derivative respectively to design an excimer donor-acceptor pair. With the aid of a supramolecular co-assembly strategy, the material with the excimer type circularly polarized luminescent property is obtained.

Description

Technical Field

[0001] This invention specifically relates to an excimer complex type circularly polarized luminescent material and its preparation method, belonging to the field of circularly polarized luminescence. Background Technology

[0002] Circularly polarized luminescence (CPL) refers to the phenomenon where chiral luminescent systems emit differentially polarized light, exhibiting left-handed and right-handed circular polarization. It cleverly overcomes the energy loss inherent in traditional methods of obtaining circularly polarized light from linearly polarized light using optical elements. Furthermore, it holds significant application value in fields such as 3D display, bioimaging, information storage, and asymmetric synthesis, and has become a research hotspot in this field. Circularly polarized light reflects the chiral information of excited molecular states, involving the dipole arrangement of excited-state molecules, and plays a unique role in exploring the conformation and packing patterns of excited-state molecules. Currently, various methods for constructing circularly polarized luminescent materials have been developed using different types of systems, including small organic molecules, polymers, supramolecular assemblies, and metal complexes. However, many unresolved issues remain, such as endowing the system with a high asymmetry factor, excellent designability of emission color, and intelligent tunability, including controlling the emission wavelength, intensity, and signal direction of circularly polarized luminescence.

[0003] On the other hand, exciplexes, also known as excited-state charge-transfer complexes, are similar to excimers in that their formation and emission follow classic photophysical processes. They form between two different luminescent groups, D and A. Under illumination, the excited-state D* interacts strongly with the ground-state A, or the excited-state A* interacts strongly with the ground-state D, forming a new species at a new energy level. When this species is deactivated via radiative transition, exciplex emission occurs. The energy level of the exciplex is often low, causing a redshift in the emission wavelength. However, since this species exists only in the excited state, it does not affect the position of the absorption peak. In other words, the exciplex system has a large Stokes shift, which avoids phenomena such as self-absorption. Furthermore, the formation and emission processes of exciplexes are sensitive to the external environment. By changing the external environment (such as the type of solvent), the ratio of exciplex emission to localized emission (LE), the exciplex emission wavelength, and the intensity can be effectively adjusted, giving the system excellent responsiveness to external stimuli and controllability. Therefore, leveraging the advantages of the Exciplex system, such as large Stokes shift, dual emission, and stimulus-responsiveness, the preparation of exciplex-based circularly polarized luminescent materials by coupling chirality with Exciplex photophysical processes is of great significance for the development of the field of circularly polarized luminescence. However, to date, there are very few reports on exciplex-based circularly polarized luminescent materials and their preparation methods. Summary of the Invention

[0004] The purpose of this invention is to provide an excitocomplex-type circularly polarized luminescent material and its preparation method.

[0005] The exciton complex-type circularly polarized luminescent material provided by this invention consists of a pair of identical chiral exciton complex donor and acceptor molecules.

[0006] The donor is a molecular DMG prepared by covalently linking an amide bond to a chiral glutamine derivative with N,N-dimethylaniline as the head group, as shown in Formula I.

[0007]

[0008] In Equation I, R1 is C 12 -C 20 (Specifically, it can be C) 16 -C 20 More specifically, it can be C 18 Straight-chain or branched alkyl groups,

[0009] The receptor is a PG molecule prepared by covalently linking a chiral glutamine derivative with a pyrene head group via an amide bond, and its structural formula is shown in Formula II.

[0010]

[0011] In Equation II, R2 is C 12 -C 20 (Specifically, it can be C) 16 -C 20 More specifically, it can be C 18 Straight-chain or branched alkyl groups.

[0012] Specifically, the material is composed of S-DMG and S-PG, or of R-DMG and R-PG.

[0013] The present invention also provides a method for preparing the above-mentioned excitocomplex-type circularly polarized luminescent material.

[0014] The method for preparing excitocomplex-type circularly polarized luminescent materials provided by this invention includes the following steps:

[0015] Mix the chiral donor DMG and acceptor PG, add a solvent, heat until completely dissolved, cool, and let stand until a gel forms.

[0016] In the above method, the molar ratio of donor DMG to receptor PG is 1:4-4:1, specifically 1:1, and the ratio of receptor PG to organic solvent is 2mg / mL-8mg / mL.

[0017] The solvent may be selected from at least one of the following: ethyl acetate, N,N-dimethylformamide, ethanol, methylcyclohexane, and toluene;

[0018] The cooling time can be 5-15 minutes.

[0019] The above method may further include the following steps: after the obtained gel has been left to stand for 1-2 hours, it is cast onto a substrate and allowed to evaporate naturally to obtain the sample.

[0020] The applications of the above-mentioned excitocomplex-type circularly polarized luminescent materials in three-dimensional display, bioimaging, information storage, asymmetric synthesis, and asymmetric catalysis are also within the scope of protection of this invention.

[0021] Fluorescence spectroscopy of the obtained samples revealed that the fluorescence emission peak of the excitocomplex was around 460-480 nm. Fluorescence lifetime testing confirmed that the emission was excitocomplex emission.

[0022] The obtained sample was tested on a circular polarization spectrometer, and a clear CPL signal was observed. The emission position was consistent with the fluorescence spectroscopy test results, indicating the successful preparation of excitocomplex-type circularly polarized luminescent materials.

[0023] In addition, using two pairs of enantiomers, namely S-DMG+S-PG and R-DMG+R-PG, a mirrored CPL signal can be obtained.

[0024] This invention utilizes a two-component co-assembly strategy of small organic molecules to prepare materials exhibiting exciton complex-type circularly polarized luminescence properties. The invention designs exciton complex donor-acceptor pairs by covalently linking the classic exciton complex pair of N,N-dimethylaniline and pyrene to long-chain chiral glutamine derivatives. Using a supramolecular co-assembly strategy, materials exhibiting exciton complex-type circularly polarized luminescence properties are obtained. Attached Figure Description

[0025] Figure 1 The fluorescence emission spectrum is that of the DMG+PG two-component dry gel prepared in ethyl acetate in Example 1 of this invention.

[0026] Figure 2 The lifetime decay curve of fluorescence emission at 464 nm is shown for the DMG+PG two-component dry gel prepared in ethyl acetate in Example 1 of this invention.

[0027] Figure 3 The circularly polarized emission spectrum of the DMG+PG two-component dry gel prepared in ethyl acetate in Example 1 of this invention is shown.

[0028] Figure 4The fluorescence emission spectrum of the DMG+PG two-component dry gel prepared in N,N-dimethylformamide in Example 2 of this invention is shown.

[0029] Figure 5 The lifetime decay curve of fluorescence emission at 476 nm is shown for the DMG+PG two-component dry gel prepared in N,N-dimethylformamide in Example 2 of this invention.

[0030] Figure 6 The circularly polarized emission spectrum of the DMG+PG two-component dry gel prepared in N,N-dimethylformamide in Example 2 of this invention is shown. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0033] Example 1: Preparation of exciton complex donor (Formula I) and acceptor (Formula II) and materials with exciton complex-type circularly polarized luminescence properties.

[0034] (1) Synthesis of chiral long-chain chiral glutamine derivatives SG / RG:

[0035] Refer to Yuangang Li, Tianyu Wang et al., Gelating-induced supramolecular chirality of achiral porphyrins:chiroptical switch between achiral molecules and chiral assemblies, SoftMatter, 2007, 3, 1312–1317 and Xuefeng Zhu, Yuangang Li et al., Self-Assembled Ultralong Chiral Nanotubes and Tuning of Their ChiralityThrough the Mixing of Enantiomeric Component, Chem. Eur. J. 2010, 16, 8034-8040 was synthesized by the method described.

[0036] The specific steps are as follows:

[0037]

[0038] Boc-glutamic acid (2.47 g, 0.01 mol, purchased from TCI) and octadecylamine (5.39 g, 0.02 mol, purchased from Alfa) were mixed in a 250 mL round-bottom flask, and dichloromethane (200 mL, purchased from Concord Technology (Tianjin) Co., Ltd.) was added. Then, 1-ethyl-(3-dimethylamino)carbodiimide hydrochloride (EDC·HCl, 4.02 g, 0.022 mol, purchased from Inokai) and 1-hydroxybenzotriazole (HOBt, 2.97 g, 0.022 mol, purchased from Bailingwei) were added to the mixture. The resulting mixture was stirred at room temperature for 72 hours. The resulting white solid was separated by filtration and washed three times with dichloromethane (purchased from Concord Technology (Tianjin) Co., Ltd.). The crude product was dissolved in tetrahydrofuran (purchased from Concord Technology (Tianjin) Co., Ltd.) and precipitated with water. A white solid S / R-BG was obtained (6.5 g, 87% yield).

[0039] 3.575 g of S / R-BG was dispersed in 50 mL of TCM (purchased from Concord Technology (Tianjin) Co., Ltd.), and trifluoroacetic acid (TFA; 8 mL, purchased from Maclean's) was added. After stirring at room temperature for 3 hours, a white solid suspension was obtained. Excess TFA was removed by rotary evaporation, and the remaining solid was dissolved in tetrahydrofuran (THF, purchased from Concord Technology (Tianjin) Co., Ltd.), and then poured into a prepared saturated NaHCO3 (purchased from Sinopharm Group) aqueous solution. The solution was then filtered and vacuum dried to obtain a crude product (2.990 g). Recrystallization three times in 380 mL of tetrahydrofuran (purchased from Concord Technology (Tianjin) Co., Ltd.) yielded a white pure product (2.600 g, 83.95%).

[0040] The synthetic steps of the excitocomplex donor molecule DMG are as follows:

[0041]

[0042] Synthesis of S-DMG / R-DMG: 0.40 g of SG / RG (0.62 mmol) was dispersed in 50 mL of ultra-dry dichloromethane (DCM, purchased from Energie Chemicals), and 0.19 g of ultra-dry triethylamine (purchased from Bailingwei) was added. The mixture was stirred for 30 minutes. Subsequently, under ice bath conditions, 0.17 g of 4-dimethylaminobenzoyl chloride (0.93 mmol, purchased from Inocare) dissolved in 50 mL of ultra-dry DCM (purchased from Energie Chemicals) was slowly added dropwise to the above mixture using a constant pressure funnel. After stirring for 30 minutes, the ice bath was removed. The mixture was then stirred at room temperature for 24 hours. After the reaction was complete, the DCM solvent was removed by rotary evaporation. The resulting white solid was heated and dissolved in 15 mL of THF (purchased from Concord Technology (Tianjin) Co., Ltd.). After the solution was clarified, it was slowly poured into 600 mL of saturated NaHCO3 (purchased from Sinopharm Group) aqueous solution, resulting in the precipitation of a large amount of white precipitate. After standing for 8 hours, the initial product was collected by vacuum filtration and freeze-dried. Subsequently, the crude product was recrystallized three times with ethanol (purchased from Concord Technology (Tianjin) Co., Ltd.) to obtain a white solid. After vacuum drying, pure S-DMG / R-DMG products were obtained, with yields of 76.9% and 72.1%, respectively.

[0043] The structural characterization of S-DMG is as follows:

[0044] 1 H NMR (400MHz, CDCl3): δ8.77(d,J=6.1Hz,1H),8.11(d,J=8.4Hz,2H),7.78(d,J=8.4Hz,2H),4.57-4.61(m,1H),3.26-3.31(m,4H),3 .19(s,6H),2.70-2.73(m,1H),2.43-2.47(m,1H),2.14-2.21(m,2H),1.49-1.52(m,4H),1.25-1.30(m,60H),0.88(t,J=7.1Hz,6H).

[0045] MALDI-TOF-MS:C 50 H 93 N4O3, theoretical value [M+H] + m / z = 797.7242; Test result [M+H] + :m / z=797.7244.

[0046] The structural characterization of R-DMG is as follows:

[0047] 1H NMR (400MHz, CDCl3): δ8.93(d,J=6.1Hz,1H),8.18(d,J=8.4Hz,2H),7.83(d,J=8.4Hz,2H),4.67-4.71(m,1H),3.28-3.35(m,4H),3 .20(s,6H),2.89-2.93(m,1H),2.51-2.56(m,1H),2.19-2.24(m,2H),1.54-1.57(m,4H),1.26-1.31(m,60H),0.88(t,J=7.1Hz,6H).

[0048] MALDI-TOF-MS:C 50 H 93 N4O3, theoretical value [M+H] + m / z = 797.7242; Test result [M+H] + :m / z=797.7240.

[0049] The steps involved in the synthesis of the PG molecule, the excitokinin receptor:

[0050]

[0051] Synthesis of S-PG / R-PG: 0.60 g SG / RG (0.92 mmol) was dispersed in 60 mL of chloroform (TCM, purchased from Concord Technology (Tianjin) Co., Ltd.) and stirred for 30 minutes. Then, 0.34 g 1-pyrene carboxylic acid (1.38 mmol, purchased from Acros) was added, followed by 0.26 g 1-ethyl-(3-dimethylamino)carbodiimide hydrochloride (EDC·HCl, 1.38 mmol, purchased from Inokai) and 0.19 g 1-hydroxybenzotriazole (HOBt, 1.38 mmol, purchased from Bailingwei) dissolved in 10 mL TCM, which were then added to the mixture. The mixture was stirred at room temperature for 96 hours. After the reaction was complete, the solvent was removed by rotary evaporation. The resulting yellow solid was heated and dissolved in 10 mL of DMF (purchased from Concord Technology (Tianjin) Co., Ltd.). After dissolution and clarification, the solution was slowly poured into 500 mL of saturated NaHCO3 (purchased from Sinopharm Group) aqueous solution, resulting in the precipitation of a large amount of yellowish-brown precipitate. After standing for 8 hours, the initial product was collected by vacuum filtration and freeze-dried. Subsequently, the crude product was recrystallized sequentially from dimethyl sulfoxide (DMSO, purchased from Concord Technology (Tianjin) Co., Ltd.), ethanol (purchased from Concord Technology (Tianjin) Co., Ltd.), and acetone (purchased from Concord Technology (Tianjin) Co., Ltd.) to obtain a brown solid. After vacuum drying, pure S-PG / R-PG products were obtained, with yields of 67.9% and 60.5%, respectively.

[0052] The structural characterization of S / R-PG is as follows:

[0053] 1 H NMR (300MHz, CDCl3): δ8.62 (d, J = 9.0Hz, 2H), 8.02-8.24 (m, 9H), 4.86-4.89 (m, 1H), 3.25-3.35 (m, 4H) ,2.70-2.83(m,2H),2.26-2.44(m,2H),1.47-1.57(m,4H),1.21-1.25(m,60H),0.87(t,J=6.4Hz,6H).

[0054] MALDI-TOF-MS:C 58 H 92 N3O3, theoretical value [M+H] + m / z = 878.7133; Test result [M+H] + :m / z=878.7128.

[0055] The structural characterization of R-PG is as follows:

[0056] 1 H NMR (400MHz, CDCl3): δ8.65 (d, J = 8.7Hz, 1H), 8.03-8.24 (m, 9H), 4.79-4.83 (m, 1H), 3.26-3.36 (m, 4H) ,2.67-2.72(m,2H),2.22-2.44(m,2H),1.47-1.57(m,4H),1.21-1.26(m,60H),0.87(t,J=6.8Hz,6H).

[0057] MALDI-TOF-MS:C 58 H 92 N3O3, theoretical value [M+H] + m / z = 878.7133; Test result [M+H] + :m / z=878.7131.

[0058] Accurately weigh 3.64 mg of the same chiral excimer complex donor DMG and 4 mg of the excimer complex acceptor into a 5 mL screw-top sample vial. Add 1 mL of ethyl acetate, heat to completely dissolve the molecules in the solvent, and cool and stand at room temperature until gel forms.

[0059] After the obtained gel was left to stand for 2 hours, it was cast onto a quartz substrate and allowed to evaporate naturally to obtain a dry gel sample.

[0060] The obtained dry gel was subjected to fluorescence spectroscopy testing, such as... Figure 1As shown, a fluorescence emission peak is observed at 464 nm, and its fluorescence lifetime is measured to be 53.3 ns. Figure 2 The fluorescence emission can be attributed to the excitocomplex.

[0061] The obtained dry gel was subjected to circular polarization luminescence spectroscopy, as shown in the figure. Figure 3 S-DMG+S-PG two-component dry gel ( Figure 3 The solid line (glume) shows negative CPL emission at 464 nm, indicating right-handed biased CPL luminescence. The calculated luminescence asymmetry factor |glum| is -1.3 × 10⁻⁶. -3 When its enantiomer, namely R-DMG+R-PG two-component dry gel, is used, a mirror-image CPL signal is obtained ( Figure 3 ,dotted line).

[0062] Example 2: Preparation of materials with exciton complex-type circularly polarized luminescence properties in N,N-dimethylformamide

[0063] Accurately weigh 3.64 mg of the same chiral excimer complex donor DMG and 4 mg of the excimer complex acceptor into a 5 mL screw-top sample vial. Add 1 mL of N,N-dimethylformamide, heat to completely dissolve the molecules in the solvent, and cool and stand at room temperature until gel formation.

[0064] After the obtained gel was left to stand for 2 hours, it was cast onto a quartz substrate and allowed to evaporate naturally to obtain a dry gel sample.

[0065] The obtained dry gel was subjected to fluorescence spectroscopy testing, such as... Figure 4 As shown, a fluorescence emission peak is observed at 476 nm, and its fluorescence lifetime is measured to be 55.3 ns. Figure 5 The fluorescence emission can be attributed to the excitocomplex.

[0066] The obtained dry gel was subjected to circular polarization luminescence spectroscopy, as shown in the figure. (S-DMG+S-PG two-component dry gel) Figure 6 The solid line (glume) shows negative CPL emission at 476 nm, indicating right-handed biased CPL luminescence. The calculated luminescence asymmetry factor |glum| is -4.8 × 10⁻⁶. -3 When using its enantiomers, namely R-DMG+R-PG two-component dry gels ( Figure 6 (dashed line), to obtain the mirrored CPL signal.

[0067] The inventors of this invention also prepared S-DMG+S-PG two-component gels by sequentially using ethanol, methylcyclohexane, and toluene as solvents (other parameters remained unchanged), and the resulting samples also exhibited circularly polarized luminescence characteristics.

[0068] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. An exciton complex-type circularly polarized luminescent material, comprising a pair of identical chiral exciton complex donor and acceptor molecules, The donor is a molecular DMG prepared by covalently linking an amide bond to a chiral glutamine derivative with N,N-dimethylaniline as the head group, as shown in Formula I. In Equation I, R1 is C 12 -C 20 Straight-chain or branched alkyl groups The receptor is a PG molecule prepared by covalently linking a chiral glutamine derivative with a pyrene head group via an amide bond, and its structural formula is shown in Formula II. In Equation II, R2 is C 12 -C 20 Straight-chain or branched alkyl groups; The method for producing the excitocomplex-type circularly polarized luminescent material includes the following steps: Mix the chiral donor DMG and acceptor PG, add a solvent, heat until completely dissolved, cool, and let stand until a gel forms.

2. The excimer compound type circularly polarized light-emitting material according to claim 1, characterized in that: The material is composed of S-DMG and S-PG, or of R-DMG and R-PG. Where R1 is C 12 -C 20 Straight-chain or branched alkyl groups, where R2 is C 12 -C 20 Straight-chain or branched alkyl groups.

3. A method for preparing the excitocomplex-type circularly polarized luminescent material according to claim 1 or 2, comprising the following steps: Mix the chiral donor DMG and acceptor PG, add a solvent, heat until completely dissolved, cool, and let stand until a gel forms.

4. The method according to claim 3, characterized in that: In the method, the molar ratio of donor DMG to acceptor PG is 1:4-4:1; The ratio of receptor PG to organic solvent is 2 mg / mL to 8 mg / mL.

5. The method according to claim 3 or 4, characterized in that: The solvent is selected from at least one of ethyl acetate, N,N-dimethylformamide, ethanol, methylcyclohexane, and toluene.

6. The method according to claim 3 or 4, characterized in that: The cooling time is 5-15 minutes.

7. The method according to claim 3 or 4, characterized in that: The method further includes the following steps: after the obtained gel has been left to stand for 1-2 hours, it is cast onto a substrate and the organic solvent is allowed to evaporate naturally to obtain the sample.

8. The application of the excitocomplex-type circularly polarized luminescent material as described in claim 1 or 2 in the fields of three-dimensional display, information storage, asymmetric synthesis, and asymmetric catalysis.

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