Purple light chiral main body material based on paracyclophane and application of purple light chiral main body material

Abstract

The invention belongs to the technical field of organic electroluminescent materials, and particularly discloses a paracyclophane-based purple light chiral host material and application thereof. Paracyclophane is used as a molecular structure center, two paracyclophane derivatives are constructed, and the novel purple light chiral main body material is synthesized by combining indole carbazole groups on the periphery. Because the periphery is combined with an indolocarbazole group, the excellent photophysical property of indolocarbazole can be fully utilized, and through separation of cycloarane, intermolecular conjugation is broken, a novel purple light material is constructed, emission of 372 nm is realized, relatively high S1 and T1 energy levels are obtained, a chiral signal is provided for participation of cycloarane, and the material has a wide application prospect. The important significance is provided for constructing a novel chiral main body material.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and specifically discloses a violet chiral host material based on p-cyclophane and application thereof. Background Art

[0002] Cyclic polarized organic light-emitting diodes (CP-OLEDs) are advantageous for the direct emission of cyclically polarized light and have found potential applications in optical data storage, optical recognition sensors, quantum computing, rotation-dependent optical communications, and 3D displays. The most direct and effective strategy for realizing CP-OLEDs is to incorporate chiral fluorophores as emitters in the device. This approach involves introducing materials with high brightness and large asymmetry factor (g) into CPL emitters. Consequently, a large number of chiral chromophores have been developed, including fluorescence, phosphorescence, and thermally activated delayed fluorescence (TADF).

[0003] Generally, there are two ways to achieve chiral properties.

[0004] The first strategy is chiral perturbation, where cyclic polarized luminescence (CPL) signals are induced from chiral units modified directly on the molecular structure. The second is designed with intrinsic chiral optics, one of which is constructed by the 3D rotation of chiral intrinsic chiral elements. The emitter is achieved by introducing chiral alkyl chains into the platinum complex backbone. This solution-processable CP-OLED based on chiral platinum complexes achieved a maximum external quantum efficiency (EQE) higher than 12%. max ), |glum| value 10 -2 Pieters et al. first reported a TADF emitter that achieved circularly polarized light emission through dithiol chiral perturbation. Unfortunately, the device performance (EQE max : 9.1%) and |glum| value (1.3×10 -3 ) is not very satisfactory. In subsequent studies, in the same way, several research groups have realized CP-OLEDS based on chiral TADF emitters, and recently EQE max It can reach over 30%. However, its chiral emitters are difficult to synthesize and purify, which greatly increases costs. Furthermore, as chiral emitters, they can only be used in specialized equipment, which limits their application in many applications. Furthermore, CP-OLEDs can be realized by using chirality as a host material to generate chiral energy transfer. However, research in this area is limited, and has mostly focused on axially chiral octahydrobinaphthol molecules, with little exploration of other chiralities, such as spiral and planar chirality. Summary of the Invention

[0005] In order to develop new chiral host materials, the present invention uses a chiral paracyclophane as the molecular structure center and combines it with indolecarbazole with excellent physical properties to construct the R / S configuration of the purple light chiral host material MSX-tBuICz. The preparation steps are as follows:

[0006] (1) (R / S)4,16-dibromo[2.2]-cyclophane, 2-ethoxycarbonylphenylboronic acid neopentyl glycol ester, potassium carbonate, palladium acetate, S-Phos, methyltrioctylammonium chloride, and a toluene / water mixture were reacted at 100°C for 16 h. After the reaction was completed and cooled to room temperature, the mixture was extracted with dichloroethane. The organic layer was collected, washed with water, dried over anhydrous MgSO4, and evaporated to remove the solvent. Ethyl acetate and petroleum ether were then used as eluents to obtain M1.

[0007] (2) (R / S)M1 was added to polyphosphoric acid and stirred at 160°C for 12 hours. After the reaction was completed, the mixture was extracted with dichloroethane, the organic layer was collected and washed with water, dried over anhydrous MgSO4, and the solvent was removed by evaporation. After the reaction was completed, the reaction solution was poured into an ice-water bath and stirred, then extracted with ethyl acetate, the organic layer was collected and washed with water, dried over anhydrous MgSO4, and the solvent was removed by evaporation. Then, dichloroethane and petroleum ether were used as eluents, and after precipitation with methanol, the mixture was filtered to obtain (R / S)M2.

[0008] (3) 3,6-di-tert-butylcarbazole, 1-bromo-2-fluorobenzene, and cesium carbonate were dissolved in N,N-dimethylformamide, and the mixture was stirred at 150°C for 24 h. After the reaction was completed and cooled to room temperature, the mixture was extracted with dichloroethane. The organic layer was collected, washed with water, dried over anhydrous MgSO4, and evaporated to remove the solvent. Then, dichloroethane and petroleum ether were used as eluents, and after precipitation with methanol, the mixture was filtered to obtain M3.

[0009] (4) M3 was dissolved in anhydrous tetrahydrofuran solution and reacted at -78°C. After stirring for 15 minutes, n-BuLi was slowly added dropwise. After reacting for 2 hours, (R / S)M2 was dissolved in anhydrous tetrahydrofuran and injected into a flask. Stirring was continued at -78°C for 3 hours, and then the mixture was moved to room temperature and reacted for 12 hours. After the reaction was completed, methanol was added to quench the reaction. The mixture was extracted with ethyl acetate, and the organic layer was collected and washed with water, dried over anhydrous MgSO4, and evaporated to remove the solvent. Then, dichloroethane and petroleum ether were used as eluents, and after precipitation with methanol, (R / S)MSX-tBuICz was obtained.

[0010] Two R / S violet chiral host materials with different chiral configurations were synthesized through the above experimental steps. These materials have the following structures:

[0011]

[0012] The raw materials for p-cyclophane derivatives are readily available and inexpensive, the synthesis method is simple and easy to operate, and the products are easily separated with high yields. The fluorenone structure, obtained through a few steps of synthesis, is easily modifiable peripherally. The p-cyclophane is chirally stable and not susceptible to racemization, making it a promising candidate for application in chiral optoelectronic materials. The inclusion of a peripheral indolecarbazole group enables the construction of narrow-band violet emission, facilitating the construction of host materials with excellent physicochemical properties.

[0013] On the other hand, by modifying the structure of cyclophanes, two new chiral host materials with different chiral configurations were constructed. The relationship between molecular structure and performance was explored in detail, and the photophysical properties of the materials were studied in depth. The construction of new chiral host materials is of great significance to the development of CPL.

[0014] Another object of the present invention is to provide a novel violet chiral host material as a host material of the light-emitting layer for preparing an organic electroluminescent device, and to realize a solution-processed organic electroluminescent device with chirality participation by host doping.

[0015] In the light-emitting layer, the novel violet chiral material of the present invention serves as a host material, and the doping concentration of the guest material Ir(mppy)3 is 10 wt%-30 wt%.

[0016] The present invention has the following technical advantages:

[0017] 1. By utilizing the chiral characteristics of paracyclophane and combining it with the excellent physical and chemical properties of indolecarbazole, a new type of violet light chiral host material was constructed;

[0018] 2. The excellent physicochemical properties of indolecarbazole facilitate excellent photophysical performance. The smaller N / CH backbone molecular structure enables the production of short-wavelength materials, and the larger triplet energy level facilitates the development of this material as a host material. Using para-cyclophane as a chiral factor-providing unit expands the range of new chiral host materials and plays a significant role in the development of CPLs.

[0019] 3. This invention utilizes a para-cyclophane as the conjugated backbone center and constructs a chiral host material by introducing planar chirality (para-cyclophane). This allows for the construction of CP-OLEDs through chiral transfer, expanding their applications and significantly reducing costs. The application of materials exhibiting chiral circularly polarized luminescence in display devices can avoid the need for polarizers, reducing costs and providing a viable solution for even thinner displays. Furthermore, by using the polarization direction as an encryption dimension, high-security anti-counterfeiting labels (such as those for high-end products) can be developed, enhancing information encryption capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1The compound (R / S)MSX-tBuICz prepared in Example 1 was dissolved in toluene (10 -5 M) and the photoluminescence spectrum of the pure film.

[0021] Figure 2 The fluorescence (Fl) and phosphorescence (Ph) of the compound (R / S)MSX-tBuICz in Example 1 were measured at 77K.

[0022] Figure 3 This is the CV diagram of the compound (R / S)MSX-tBuICz prepared in Example 1 measured on an electrochemical workstation.

[0023] Figure 4 The compound (R / S)MSX-tBuICz prepared in Example 1 serves as the host material of the device, and the guest of the device is Ir(mppy)3. When the compound (R / S)MSX-tBuICz is used as the host material, the electroluminescence spectrum (EL) of the guest Ir(mppy)3 is shown in (a); the relationship between brightness and maximum external quantum efficiency is shown in (b); and the molecular structure of the guest compound Ir(mppy)3 in its light-emitting layer is shown in (c).

[0024] Figure 5 is the H NMR spectrum of the intermediate compound (R / S)MSX-tBuICz obtained in Example 1 ( 1 H NMR) (ac).

[0025] Figure 6 The H NMR spectrum of the compound (R / S)MSX-tBuICz prepared in Example 1 is ( 1 1H NMR). DETAILED DESCRIPTION

[0026] The following specific implementation cases are intended to further illustrate the present invention, but these specific implementation cases do not limit the scope of protection of the present invention in any way.

[0027] Example 1

[0028] The synthesis scheme of the violet chiral host material based on the present invention is as follows:

[0029]

[0030] Synthesis of compound (R / S)M1:

[0031] A 100 mL two-necked flask was charged with (1.0 g, 2.73 mmol) (R / S)-4,16-dibromo[2.2]-cyclophane, neopentyl glycol 2-ethoxycarbonylphenylboronate (2.86 g, 10.92 mmol), potassium carbonate (1.73 g, 16.38 mmol), palladium acetate (30.66 mg, 0.136 mmol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-Phos) (112.13 mg, 0.27 mmol), methyltrioctylammonium chloride (5 mg, 0.012 mmol), and a magnet. Toluene and water (30 ml:6 ml) were then added to the 100 mL two-necked flask. The pale yellow reaction solution was reacted at 100°C for 16 h under a nitrogen atmosphere. After the reaction was complete, the reaction mixture was extracted three times with CH2Cl2 (3×100 mL), washed three times with water (3×100 mL), dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure to obtain a gray oil. Column chromatography was performed using 10:1 PE:EA as the eluent to obtain 612 mg of the pure product (R / S)M1 as a light yellow oil, with a yield of 44.5%. 1 H NMR (400MHz, CDCl3) δ7.70 (dd, J=7.7, 1.5Hz, 2H), 7.61 (dd, J=7.7, 1.3Hz, 2H ),7.50(td,J=7.6,1.5Hz,2H),7.40(td,J=7.6,1.3Hz,2H),6.73–6.64(m,4H) ,6.58(d,J=1.8Hz,2H),3.89–3.78(m,4H),3.10(dtd,J=12.7,10.7,5.0Hz,4 H), 2.87 (ddd, J=13.6, 10.4, 6.3Hz, 2H), 2.62 (ddd, J=13.2, 10.2, 6.3Hz, 2H).

[0032] Synthesis of compound (R / S)M2:

[0033] Take a clean and dry 100mL single-necked flask, add 612mg of (R / S)M1 (4.72mmol), then add 30ml of polyphosphoric acid, and stir at 160°C for 12 hours. After the reaction is completed, the reaction solution is poured into an ice-water bath and stirred, then extracted three times with ethyl acetate (EA) (3×100mL), washed three times with water (3×100mL), dried over anhydrous magnesium sulfate, and distilled under reduced pressure to remove the solvent to obtain an orange powdery solid. The solid was purified by beating with methanol solvent, filtered after beating, and the upper filter residue was taken to finally obtain 87mg of orange powdery solid (R / S)M2 with a yield of 17.4%. 1H NMR(400MHz, CDCl3)δ7.50(d,J=7.6Hz,2H),7.39(td,J=7.5,1.3Hz,2H),7.07(t d,J=7.4,0.9Hz,2H),6.90(dd,J=7.3,1.1Hz,2H),6.72(d,J=7.9Hz,2H),6.56(d, J=7.9Hz,2H),4.38(ddd,J=13.1,9.9,4.5Hz,2H),3.88(ddd,J=13.9,10.0,4.1H z, 2H), 3.17 (ddd, J = 14.2, 10.2, 4.5 Hz, 2H), 2.99 ( ddd, J = 13.9, 10.1, 4.1 Hz, 2H).

[0034] Synthesis of compound M3:

[0035] A 100 mL two-necked flask was charged with 1 g of 3,6-di-tert-butylcarbazole (1 g, 3.57 mmol), 1-bromo-2-fluorobenzene (521.89 mg, 2.98 mmol), and cesium carbonate (2.91 g, 8.94 mmol). The mixture was dissolved in 40 mL of N,N-dimethylformamide and vacuum-treated. The mixture was placed in a thermostatic magnetic stirrer and stirred at 150°C under nitrogen for 24 h. After the reaction was completed, the mixture was cooled to room temperature and the reaction mixture was extracted three times with CH2Cl2 (3 × 100 mL) and washed three times with water (3 × 100 mL). The mixture was dried over anhydrous magnesium sulfate and the solvent was removed by distillation under reduced pressure. The mixture was then directly slurried with methanol for purification. After slurrying, the residue was filtered and the upper layer was filtered to obtain 943 mg of a white powdery solid M3 with a yield of 75%. 1 H NMR (300MHz, CDCl3) δ8.14 (d, J = 1.9 Hz, 2H), 7.85 (dd, J = 7.9, 1.5 Hz, 1H), 7.51–7.38 (m, 5H), 6.99 (d, J = 8.6 Hz, 2H), 1.46 (s, 18H).

[0036] Synthesis of compound (S)MSX-tBuICz:

[0037] M3 (514.2 mg, 1.45 mmol) was added to a 100 mL two-necked flask and dissolved in anhydrous tetrahydrofuran. The mixture was reacted at -78°C and stirred for 15 minutes. After that, 0.7 mL of n-BuLi was slowly added dropwise. After a 2-hour reaction, (S)M2 (200 mg, 0.48 mmol) was dissolved in anhydrous tetrahydrofuran and injected into the 100 mL two-necked flask. Stirring was continued at -78°C for 3 hours before the mixture was allowed to react at room temperature for 12 hours. After completion of the reaction, methanol was added to quench the reaction. The mixture was extracted three times with ethyl acetate (3 × 100 mL) and washed three times with water (3 × 100 mL). The mixture was dried over anhydrous magnesium sulfate and the solvent was removed by distillation under reduced pressure. The mixture was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 2:1) to afford a white solid. This solid was further recrystallized from CH2Cl2 and CH3OH to yield 94 mg of (S)MSX-tBuICz as a white powder in an 18% yield. 1 H NMR(400MHz, CDCl3) δ8.16(dd,J=8.9,3.2Hz,4H),8.04(d,J=2.0Hz,2H),7.60(dd,J =7.2,1.8Hz,4H),7.30–7.15(m,8H),7.00–6.94(m,2H),6.84–6.74(m,4H),6.58(d, J=7.1Hz,2H),6.45(d,J=7.1Hz,2H),6.12(t,J=7.5Hz,2H),3.04(dt,J=14.6,7.6Hz ,4H),2.76–2.66(m,2H),2.39(dt,J=13.0,8.7Hz,2H),1.44(s,19H),0.85(s,17H).

[0038] M3 (514.2 mg, 1.45 mmol) was added to a 100 mL two-necked flask and dissolved in anhydrous tetrahydrofuran. The mixture was reacted at -78°C and stirred for 15 minutes. After that, 0.7 mL of n-BuLi was slowly added dropwise. After a 2-hour reaction, (R)M2 (200 mg, 0.48 mmol) was dissolved in anhydrous tetrahydrofuran and injected into the 100 mL two-necked flask. Stirring was continued at -78°C for 3 hours before the mixture was allowed to react at room temperature for 12 hours. After completion of the reaction, methanol was added to quench the reaction. The mixture was extracted three times with ethyl acetate (3 × 100 mL) and washed three times with water (3 × 100 mL). The mixture was dried over anhydrous magnesium sulfate and the solvent was removed by distillation under reduced pressure. The residue was separated by column chromatography using PE and CH2Cl2 as eluents (volume ratio = 2:1) to afford a light yellow solid. This was further recrystallized from CH2Cl2 and CH3OH to obtain 94 mg of (R)MSX-tBuICz as a light yellow powder in an 18% yield. 1H NMR(400MHz, CDCl3) δ8.16(dd,J=8.9,3.2Hz,4H),8.04(d,J=2.0Hz,2H),7.60(dd,J =7.2,1.8Hz,4H),7.30–7.15(m,8H),7.00–6.94(m,2H),6.84–6.74(m,4H),6.58(d, J=7.1Hz,2H),6.45(d,J=7.1Hz,2H),6.12(t,J=7.5Hz,2H),3.04(dt,J=14.6,7.6Hz ,4H),2.76–2.66(m,2H),2.39(dt,J=13.0,8.7Hz,2H),1.44(s,19H),0.85(s,17H).

[0039] Example 2

[0040] The compound (R / S)MSX-tBuICz in Example 1 was dissolved in chlorobenzene and heated to 100° C. Its solubility was 10 mg / mL.

[0041] The compound (R / S)MSX-tBuICz in Example 1 was dissolved in toluene to prepare 10 -5 M solution, and tested its UV-visible absorption (UV), photoluminescence spectrum (PL) and photoluminescence spectrum (PL) of pure film. Figure 1 It can be seen that the UV-visible absorption spectrum of the compound (R / S)MSX-tBuICz in solution has roughly two absorption peaks of different intensities: the absorption peak at short wavelength (280-325nm) is mainly attributed to the π-π* transition absorption of the molecule; the absorption peak at long wavelength (365nm) is attributed to the intramolecular charge transfer (ICT) transition absorption peak. Figure 1 As shown in the figure, the maximum emission peak of the compound (R / S)MSX-tBuICz is 372nm, in the violet region. In the pure film, the maximum emission peak of the compound (R / S)MSX-tBuICz is at 552nm, which is red-shifted by 180nm. This red-shift is caused by aggregation in the pure film.

[0042] Example 3

[0043] The fluorescence (Fl) and phosphorescence (Ph) of the compound (R / S)MSX-tBuICz in Example 1 were measured at low temperature. Figure 2 As shown, based on the emission starting points of the Fl and Ph spectra, the S1 / T1 energy levels of (R / S)MSX-tBuICz can be calculated to be 3.41 / 2.61 eV.

[0044] Example 4

[0045] The CV data of the compound (R / S)MSX-tBuICz in Example 1 were tested in a nitrogen atmosphere on an electrochemical workstation. Figure 3 As shown, the HOMO of (R / S)MSX-tBuICz is -5.51 eV and the LUMO is -2.18 eV.

[0046] Example 5

[0047] The application of the compound (R / S)MSX-tBuICz in Example 1 in an organic electroluminescent device. The compound is used as a dopant in the light-emitting layer of the device, and the device structure is an organic electroluminescent diode of ITO / PEDOT:PSS (35nm) / PVK (60nm) / EML ((R / S)MSX-tBuICz:Ir(mppy)3 (10wt%, 20wt%, 30wt%) / DPEPO (10nm) / TmPyPB (50nm) / LiF (1nm) / Al (120nm). Among them, PEDOT:PSS is a hole injection layer; PVK is a hole transport layer; DPEPO is a hole blocking layer; TmPyPB is an electron transport layer; LiF / Al is a cathode. EML is a light-emitting layer, including (R / S)MSX-tBuICz and Ir(mppy)3, and the doping concentration of Ir(mppy)3 in the light-emitting layer is 10, 20, and 30wt%, respectively. Figure 4 As shown in (a), (R / S)MSX-tBuICz is used as the host material, showing the electroluminescence spectrum of the Ir(mppy)3 device after doping with the host material. The emission is at 512-516nm, which has little effect on the spectrum of the guest material, making it an ideal host material. The devices with 10, 20, and 30 wt% doping of the guest material Ir(mppy)3 achieve maximum external quantum efficiencies of 1.0%, 1.6%, and 1.3%, respectively. Figure 4 (b) shown; wherein the molecular structure of compound Ir(mppy)3 is as shown Figure 4 (c) shown.

[0048] The device solution processing preparation method: The substrate is pretreated with oxygen plasma to enhance the functionality of the ITO thin film. Then, PEDOT:PSS is spin-coated onto the ITO substrate at 3200 rpm for 30 seconds and annealed at 150°C for 15 minutes to form a 35 nm thick hole injection layer. A prepared host-guest mixed solution (with the luminescent layer Ir(mppy)3 doped at 10, 20, and 30 wt% in chlorobenzene (10 mg / ml)) is spin-coated onto the hole transport layer at 80°C and annealed for 30 minutes. DPEPO, TmPyPB, and a LiF / Al cathode are then sequentially evaporated onto the luminescent layer, hole blocking layer, and electron transport layer to produce a device containing the luminescent molecule of the present invention.

[0049] Example 6

[0050] The intermediate H NMR spectrum of the compound (R / S)MSX-tBuICz prepared in Example 1 is as follows: Figure 4 ( 1 HNMR) (ac).

[0051] Example 7

[0052] The H NMR spectrum of the compound (R / S)MSX-tBuICz prepared in Example 1 is shown in FIG5 ( 1 1H NMR).

[0053] Although the present invention has been described in conjunction with the preferred embodiments, the present invention is not limited to the above embodiments, and it should be understood that the appended claims summarize the scope of the present invention. Under the guidance of the inventive concept, those skilled in the art should realize that certain changes made to the various embodiments of the present invention will be covered by the spirit and scope of the claims of the present invention.

Claims

1. A violet chiral host material based on paracyclophane, characterized by: The molecular structure of the violet chiral host material is shown below:

2. The violet chiral host material based on paracyclophane according to claim 1, characterized in that: The synthesis method of the violet chiral host material is as follows: using 4,16-dibromo[2.2]-p-cyclophane as the intermediate core, then combining the indolecarbazole group through the periphery, and synthesizing the violet chiral host material based on p-cyclophane through Suzuki coupling, cyclization and dehalogenation cyclization reaction.

3. An application of the violet chiral host material based on paracyclophane as claimed in claim 1, characterized in that: The violet chiral host material is used for preparing an organic electroluminescent device.

4. The use of the violet chiral host material based on paracyclophane as claimed in claim 3, characterized in that: The violet chiral host material is used as a host material of a light-emitting layer of an organic electroluminescent device.

5. The use of the violet chiral host material based on paracyclophane as claimed in claim 4, characterized in that: The guest material of the light-emitting layer is Ir(mppy)3.

6. The use of the violet chiral host material based on paracyclophane as claimed in claim 5, characterized in that: The doping concentration of the guest material in the light-emitting layer is 10 wt%-30 wt%.

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