Fluorenyl dark red luminescent material and preparation method thereof

Abstract

The invention discloses a fluorenyl dark red luminescent material which adopts 9, 9-diphenylfluorene or 9, 9 '-spirobifluorene as a basic skeleton, and 6, 13-bis (triisopropyl silyl ethynyl) pentacene is introduced into a site 2 of a fluorenyl molecular skeleton; the preparation method comprises the following steps: carrying out a coupling reaction on 2-bromo-6, 13-bis (triisopropyl silyl ethynyl) pentacene and 2-(9, 9-diphenyl-9H-fluorene-2-yl)-4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborane or 2-(9, 9 '-spirobis [fluorene]-2-yl)-4, 4, 5, 5-tetramethyl-1, 3, 2-dioxaborane, so as to obtain a compound 2-DTIPSPcDPF or a compound 2-DTIPSPcSBF, and carrying out a coupling reaction on the compound 2-DTIPSPcDPF or the compound 2-DTIPSPcSBF and the compound 2-DTIPSPcSBF, so as to obtain the compound 2- The compound prepared by the invention has excellent luminescent property and good thermal stability; the fluorenyl dark red material has the advantages of low cost of skeleton raw materials and simple synthesis steps, provides a new thought for designing and synthesizing a novel fluorenyl dark red material, and can be applied to the field of organic electroluminescent devices or fluorescence sensors.

Description

Technical Field

[0001] This invention relates to the field of luminescent materials technology, specifically to a fluorene-based deep red luminescent material and its preparation method. Background Technology

[0002] Deep red luminescent materials, due to their long-wavelength emission characteristics, have significant application value in fields such as organic light-emitting diodes (OLEDs), solid-state lighting, fluorescence imaging, and laser displays. Currently reported deep red luminescent materials mainly include small organic molecule fluorescent materials, metal complex materials, and polymer materials. However, metal complex materials are costly and highly toxic, limiting their application in the biological field; polymer materials suffer from low luminescent color purity and complex processing techniques; and most small organic molecule materials exhibit low luminescent efficiency, poor thermal stability, and poor color purity, making it difficult for existing deep red luminescent materials to meet practical application requirements.

[0003] Fluorenyl compounds, represented by 9,9-diphenylfluorene and 9,9'-spirodifluorene, possess wide band gaps and rigid planar (e.g., 9,9-diphenylfluorene) or three-dimensional orthorhombic spirocyclic (e.g., 9,9'-spirodifluorene) structures, providing efficient carrier transport channels and effectively suppressing intermolecular π-π stacking, significantly reducing luminescence quenching and thus improving material stability. Currently, these fluorenyl compounds have demonstrated excellent performance in the blue-green and deep blue light regions. Achieving a redshift of the emission spectrum of fluorenyl materials to the deep red region through molecular design, while maintaining good stability, is a core challenge and important research direction in this field. This invention relates to a deep red luminescent fluorenyl compound, which possesses excellent luminescent properties, good thermal stability, low-cost scaffold raw materials, and a simple synthesis procedure, providing a new approach for designing and synthesizing novel fluorenyl deep red materials. Summary of the Invention

[0004] The purpose of this invention is to provide a fluorene-based deep red luminescent material with excellent deep red luminescence properties and good thermal stability, as well as a simple and economical method for preparing the fluorene-based deep red luminescent material.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a fluorene-based deep red luminescent material, the general structural formula of which is shown in Formula I:

[0007] ;

[0008] Wherein, R is 9,9-diphenylfluorene or 9,9'-spirodifluorene, as shown in the following structural formula:

[0009] or .

[0010] This invention also provides a method for preparing a fluorene-based deep red luminescent material, comprising the following steps:

[0011] (1) 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene and 2-(9,9-diphenyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane were coupled to obtain [(2-(9,9-diphenyl-9H-fluoren-2-yl)pentabenzene-6,13-diyl)bis(ethynyl-2,1-diyl)]bis(triisopropylsilane), abbreviated as 2-DTIPSPcDPF:

[0012] ;

[0013] In step (1), the 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene has the following structural formula:

[0014] ;

[0015] In step (1), the structural formula of 2-(9,9-diphenyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane is as follows:

[0016] ;

[0017] The reaction route for step (1) is shown in equation II-1:

[0018] ;

[0019] (2) 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene and 2-(9,9'-spirobis[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane were coupled to obtain [(2-(9,9'-spirobis[fluorene]-2-yl)pentabenzene-6,13-diyl)bis(ethynyl-2,1-diyl)]bis(triisopropylsilane), abbreviated as 2-DTIPSPcSBF:

[0020] ;

[0021] In step (2), the structural formula of 2-(9,9'-spirobis[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane is as follows:

[0022] ;

[0023] The reaction route for step (2) is shown in equation II-2:

[0024] .

[0025] Preferably, steps (1) and (2) are both Suzuki coupling reactions; the catalyst is 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride; the reaction is carried out in an organic solvent and water under light-protected and alkaline conditions, and then heated to obtain the product.

[0026] Preferably, the alkaline conditions are anhydrous potassium carbonate, the organic solvent is deoxygenated tetrahydrofuran, the heating temperature is 60-64°C, and the reaction time is 20-24 h.

[0027] Preferably, the volume ratio of the organic solvent to water is 4.5 to 5.5:1.

[0028] Preferably, the molar ratio of 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene to 2-(9,9-diphenyl-9H-fluorene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane or 2-(9,9'-spirodi[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride and anhydrous potassium carbonate is 1:1.2~1.25:0.1~0.2:3.5~4.5.

[0029] The design principle of this invention is to connect 9,9-diphenylfluorene, 9,9'-spirodifluorene and pentaphenyl groups to expand the conjugated system and reduce the band gap; the rigidity of the fluorene group and the spirocyclic structure inhibit the π-π stacking of molecules; so that the emission spectrum of the material is red-shifted to the deep red region, while retaining the efficient carrier transport capability of the fluorene group, reducing emission quenching and improving the stability of the material.

[0030] Compared with existing technologies, the advantages of this invention are: the compound possesses excellent photoelectric properties, good thermal stability, and high color purity; the raw materials are readily available, the synthesis route is simple, and it is suitable for large-scale preparation. This strategy of achieving deep red luminescence through structural modulation based on the classic blue-green light framework provides a new direction for developing efficient, stable, and low-cost deep red luminescent materials, which can be applied to organic electroluminescent devices and fluorescence sensors. Attached Figure Description

[0031] Figure 1 UV spectrum of 2-DTIPSPcDPF;

[0032] Figure 2 PL spectrum of 2-DTIPSPcDPF;

[0033] Figure 3 Thermodynamic weight loss curve of 2-DTIPSPcDPF;

[0034] Figure 4For 2-DTIPSPcDPF 1 HNMR spectrum;

[0035] Figure 5 For 2-DTIPSPcDPF 13 CNMR spectrum;

[0036] Figure 6 Time-of-flight mass spectra of 2-DTIPSPcDPF;

[0037] Figure 7 For 2-DTIPSPcSBF 1 HNMR spectrum;

[0038] Figure 8 The time-of-flight mass spectrum of 2-DTIPSPcSBF. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] Preparation of [(2-(9,9-diphenyl-9H-fluorene-2-yl)pentaphenyl-6,13-diyl)bis(acetylene-2,1-diyl)]bis(triisopropylsilane), i.e., 2-DTIPSPcDPF.

[0042] Specific preparation steps: Add 0.50 g of 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene (0.70 mmol), 0.40 g of 2-(9,9-diphenyl-9H-fluorene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (0.85 mmol), 0.05 g of 1,1'-bisdiphenylphosphine ferrocene palladium dichloride (0.07 mmol), and 0.40 g of anhydrous potassium carbonate (2.80 mmol) to a 150 mL round-bottom flask. Then, remove oxygen from the system by purging five times. Add a mixture of deoxygenated tetrahydrofuran and water (THF / water = 5 / 1). The molar ratio of 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene, 2-(9,9-diphenyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and anhydrous potassium carbonate was 1:1.2:0.1:4. The volume ratio of deoxygenated tetrahydrofuran to water was 5:1. The reactants were then heated to 60 °C and reacted for 20 h in the dark. After the reaction was completed, the reaction system was naturally cooled to room temperature and poured into a 500 mL separatory funnel. The mixture was extracted three times with water and CH2Cl2 (2:1, v / v). The organic phase was dried over anhydrous magnesium sulfate and then separated by silica gel column chromatography using petroleum ether-dichloromethane (6:1:1, v / v) as the eluent. The product was a dark green solid. All of the above operations must be performed in the dark.

[0043] The reaction route is shown in equation II-1:

[0044] .

[0045] The qualitative detection data of the dark green solid obtained from reaction route II-1 are as follows:

[0046] 1H NMR (400 MHz, CDCl3):8.09 (d, J = 10.0 Hz, 2H), 8.06 (d, J = 10.0Hz, 2H), 8.04 (s, 1H), 7.99 (d, J = 10.0 Hz, 1H), 7.96 (d, J = 10.0 Hz, 2H),7.94 (d, J = 10.0 Hz, 1H), 7.87 (d, J = 5.0 Hz, 1H), 7.86 (d, J = 5.0 Hz,1H), 7.85 (s, 1H), 7.83 (s, 1H), 7.72 (s, 1H), 7.70 (s, 1H), 7.51 (d, J = 5.0Hz, 1H), 7.49 (t, J = 10.0 Hz, 2H), 7.46 (t, J = 10.0 Hz, 1H), 7.44 (t, J =10.0 Hz, 1H), 7.42 (t, J = 10.0 Hz, 1H), 7.33-7.27 (m, 6H), 1.58 (s, 2H),1.47-1.39 (m, 36H), 1.31 (d, J = 10.0 Hz, 3H), 1.28 (d, J = 10.0 Hz, 3H)。

[0047] 13 C NMR (101 MHz, CDCl3):152.10, 151.57, 145.92, 140.34, 139.88,139.82, 138.41, 132.39, 132.34, 132.30, 131.45, 130.99, 130.77, 130.71,130.63, 129.30, 128.71, 128.37, 128.25, 127.93, 127.67, 126.86, 126.77,126.56, 126.51, 126.34, 126.12, 126.07, 125.89, 125.08, 120.67, 120.38,118.47, 118.26, 107.24, 107.18, 104.74, 104.67, 77.36, 77.04, 76.72, 65.70,53.45, 31.54, 30.17, 29.74, 19.06, 19.04, 11.72, 1.06。

[0048] MS(ESI): The experimental value of m / z was 955.078 (the theoretical value is 954.500).

[0049] The dark green solid obtained from reaction route II-1 above is 2-DTIPSPcDPF, and its structural formula is shown below:

[0050] .

[0051] The UV-Vis absorption spectrum of 2-DTIPSPcDPF in toluene solution is shown below. Figure 1 As shown in the figure, compound 2-DTIPSPcDPF has a strong absorption capacity for short-wavelength light in the ultraviolet and visible regions, with a maximum excitation wavelength of 392 nm.

[0052] The photoluminescence spectrum of 2-DTIPSPcDPF in toluene solution is as follows: Figure 2 As shown in the figure, the maximum emission wavelength of compound 2-DTIPSPcDPF is located at 660 nm, which is a deep red luminescent material.

[0053] The thermodynamic weight loss curve of 2-DTIPSPcDPF is as follows: Figure 3 As shown in the figure, 2-DTIPSPcDPF has good thermal stability, and its thermodynamic decomposition temperature is 385.7 ℃.

[0054] 2-DTIPSPcDPF 1 The H NMR spectrum is as follows: Figure 4 As shown, the peaks at different positions in the spectrum correspond to the hydrogen atoms on the fluorenyl group and pentanebenzene in the molecule, as well as the alkyl hydrogen atoms on the triisopropylsilyl group, verifying that the hydrogen atom structure of 2-DTIPSPcDPF matches the designed molecular structure.

[0055] The ¹³C NMR spectrum of 2-DTIPSPcDPF is as follows: Figure 5 As shown, the spectral peaks correspond to the carbon skeletons of fluorenyl and pentanebenzene, as well as the carbon of triisopropylsilyl, confirming that the carbon skeleton structure of 2-DTIPSPcDPF conforms to the target molecule design.

[0056] The time-of-flight mass spectrum of 2-DTIPSPcDPF is shown below. Figure 6 As shown in the figure, the peak at m / z=955.078 is the molecular ion peak of 2-DTIPSPcDPF, and the peak corresponds to the molecular formula of this material (C). 69 H 70 The molecular weight of Si2 is consistent with the theoretical molecular weight (954.49), proving that the material obtained is the target material.

[0057] In summary Figure 4 , Figure 5 and Figure 6 Together, they confirmed the correctness of the structure of the target product 2-DTIPSPcDPF.

[0058] Example 2

[0059] Example 2, to verify the correctness of reaction formula I, further synthesized a pentane compound, 2-DTIPSPcSBF, with 9,9'-spirodifluorene as the backbone.

[0060] Specific preparation steps: Add 0.50 g of 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene (0.70 mmol), 0.38 g of 2-(9,9'-spirobi[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane (0.85 mmol), 0.05 g of 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride (0.07 mmol), and 0.40 g of anhydrous potassium carbonate (2.80 mmol) to a 150 mL round-bottom flask. Then, remove oxygen from the system by purging five times. Add a mixture of deoxygenated tetrahydrofuran and water (THF / water = 5 / 1). The molar ratio of 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene, 2-(9,9'-spirodi[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride, and anhydrous sodium carbonate was 1:1.2:0.1:4. The volume ratio of deoxygenated tetrahydrofuran to water was 5:1. The reactants were then heated to 64°C and reacted for 24 h in the dark. After the reaction was completed, the reaction system was naturally cooled to room temperature and poured into a 500 mL separatory funnel. The mixture was extracted three times with water and CH2Cl2 (2:1, v / v). The organic phase was dried over anhydrous magnesium sulfate and then separated by silica gel column chromatography using petroleum ether-dichloromethane (6:1:1, v / v). The product was a dark green solid. All of the above operations must be performed in the dark.

[0061] The reaction route is shown in equation II-2:

[0062] .

[0063] The qualitative detection data of the dark green solid obtained from reaction route II-2 are as follows:

[0064] 1H NMR (400 MHz, CDCl3): 9.18 (d, J = 10.0 Hz, 2H), 9.14 (d, J = 10.0Hz, 2H), 7.93 (d, J = 10.0 Hz, 1H), 7.91 (d, J = 10.0 Hz, 1H), 7.85 (s, 1H),7.83 (s, 1H), 7.81 (s, 1H), 7.76 (d, J = 5.0 Hz, 1H), 7.74 (d, J = 5.0 Hz,1H), 7.49 (t, J = 10.0 Hz, 2H), 7.47 (t, J = 10.0 Hz, 1H), 7.33 (s, 1H), 7.18(m, 1H), 7.10 (t, J = 5.0 Hz, 1H), 7.08 (t, J = 5.0 Hz, 1H), 6.77-6.72 (m,4H), 1.47 (m, 18H), 1.27 (d, J = 10.0 Hz, 6H), 1.21 (d, J = 10.0 Hz, 6H),1.18 (d, J = 10.0 Hz, 6H).

[0065] MS(ESI): The experimental value of m / z was 952.848 (the theoretical value is 952.490).

[0066] The dark green solid obtained from step II-2 of the above reaction is 2-DTIPSPcSBF, and its structural formula is shown below:

[0067] .

[0068] Figure 7 and Figure 8 They are 2-DTIPSPcSBF 1 HNMR spectrum and time-of-flight mass spectrum, among which Figure 7 The position, number, and intensity of the NMR peaks verified that the hydrogen atom distribution of 2-DTIPSPcSBF matched the designed structure of the target molecule; Figure 8 The peak at m / z = 952.846 is the molecular ion peak of 2-DTIPSPcSBF, which is highly consistent with the theoretical molecular weight of the target molecule. Together, these peaks confirm the correctness of the structure of the target product 2-DTIPSPcSBF, thus demonstrating the general applicability of reaction formula I. Furthermore, the product 2-DTIPSPcSBF also exhibits excellent deep red luminescence properties, with a maximum emission peak at 655 nm at an excitation wavelength of 392 nm.

Claims

1. A fluorene-based deep red luminescent material, characterized in that, The general formula for the material structure is shown in Formula I: ； Wherein, R is 9,9-diphenylfluorene or 9,9'-spirodifluorene, as shown in the following structural formula: or .

2. The preparation method of the fluorene-based deep red luminescent material as described in claim 1, characterized in that, Includes the following steps: (1) 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene and 2-(9,9-diphenyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane were coupled to obtain [(2-(9,9-diphenyl-9H-fluoren-2-yl)pentabenzene-6,13-diyl)bis(ethynyl-2,1-diyl)]bis(triisopropylsilane), abbreviated as 2-DTIPSPcDPF: ； (2) 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene and 2-(9,9'-spirobis[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane were coupled to obtain [(2-(9,9'-spirobis[fluorene]-2-yl)pentabenzene-6,13-diyl)bis(ethynyl-2,1-diyl)]bis(triisopropylsilane), abbreviated as 2-DTIPSPcSBF: 。 3. The method for preparing the fluorene-based deep red luminescent material according to claim 2, characterized in that, Steps (1) and (2) are both Suzuki coupling reactions; the catalyst is 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride; the reaction is carried out in an organic solvent and water under light-protected and alkaline conditions, and then heated to obtain the product.

4. The method for preparing the fluorene-based deep red luminescent material according to claim 3, characterized in that, The alkaline conditions are anhydrous potassium carbonate, the organic solvent is deoxygenated tetrahydrofuran, the heating temperature is 60-64℃, and the reaction time is 20-24h.

5. The method for preparing the fluorene-based deep red luminescent material according to claim 3, characterized in that, The volume ratio of the organic solvent to water is 4.5~5.5:

1.

6. The method for preparing the fluorene-based deep red luminescent material according to claim 2, characterized in that, The molar ratio of 2-bromo-6,13-bis(triisopropylsilylethynyl)pentabenzene to 2-(9,9-diphenyl-9H-fluorene-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane or 2-(9,9'-spirodi[fluorene]-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborane, 1,1'-bis(diphenylphosphine)ferrocene palladium dichloride and anhydrous potassium carbonate is 1:1.2-1.25:0.1-0.2:3.5-4.5.

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