A liquid room temperature phosphorescent organic compound, and a preparation method and application thereof

Abstract

The application discloses a liquid room-temperature phosphorescent organic compound and a preparation method and application thereof, and a structural formula of the organic compound is shown in the following formula: wherein, ring A is selected from pyridine or furan; ring D is selected from pyrrole, thiophene or benzene; G1 and G2 are independently selected from hydrogen, bromine, iodine, ester group, hydroxyl group, cyano group or alkoxy group; R1 is C y H 2y L, and L is halogen. The organic compound in the application exists in a liquid form at room temperature, realizes organic room-temperature phosphorescence, has excellent processing performance and flexibility. The material has strong fluidity, and the compatibility of the material makes the material easy to be mixed with other materials, and the material is easy to be filled in containers of various shapes and narrow spaces. The synthesis route of the application has the advantages of low price of required raw materials, less influence on environment, easy recycling, short synthesis time, high yield and large amount of synthesis in a short time.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new materials, and particularly relates to a liquid room-temperature phosphorescent organic compound and a preparation method and application thereof. BACKGROUND

[0002] Most of the current organic room-temperature phosphorescent (RTP) materials exist in the form of solid or powder. However, the rigid matrix environment inevitably has problems such as poor processing performance and complex preparation process.

[0003] Liquid room-temperature phosphorescence refers to the phenomenon that an organic compound in a liquid form at room temperature can still emit phosphorescence after the excitation source is removed (i.e. stopping irradiation) after absorbing light energy. Such compounds have excellent processing performance and flexibility, and have broad application prospects in the fields of information anti-counterfeiting, biological imaging and optoelectronic devices. Therefore, liquid materials have always been the research focus of flexible light-emitting materials.

[0004] However, strong molecular non-radiative decay and oxygen easily quench the triplet excitons, making it extremely difficult to achieve liquid RTP emission. For most pi-conjugated chromophores, strong pi-pi interactions lead to compact stacking and elevated melting points, making it extremely difficult to achieve liquid phosphorescence at room temperature. The currently reported single-component RTP liquids mainly exist in the structure of alkylated 1,2-diketones, and are mainly supercooled liquids with high viscosity, which need additional thermal annealing process. SUMMARY

[0005] The technical problem to be solved by the application is to overcome the deficiencies and defects mentioned in the background, and to provide a liquid room-temperature phosphorescent organic compound and a preparation method and application thereof.

[0006] To solve the above technical problems, the technical solution provided by the application is:

[0007] A liquid room-temperature phosphorescent organic compound has the following structural formula:

[0008]

[0009] wherein: ring A is selected from pyridine or furan;

[0010] ring D is selected from pyrrole, thiophene or benzene;

[0011] G1 and G2 are independently selected from hydrogen, bromine, iodine, ester group, hydroxyl group, cyano group or alkoxy group; the ester group is -COOR', wherein R' represents -C n H 2n+1 n is a natural number, 1≤n≤24; the alkoxy group is -OC x H 2x+1 x is a natural number, 1≤x≤24;

[0012] R1 is C y H 2y L, wherein L is halogen, y is a natural number, 1≤y≤24.

[0013] Further, ring A is pyridine, and ring D is pyrrole.

[0014] Further, G1 is -OC2H5.

[0015] Further, G2 is -COOCH3.

[0016] Further, G1 and G2 are connected on the heterocycle.

[0017] Further, L is Br.

[0018] Further, R1 is connected on the heterocycle.

[0019] Further, the liquid room temperature phosphorescent organic compound is selected from the following structural formula:

[0020] .

[0021] The present application also provides a preparation method of the liquid room temperature phosphorescent organic compound, characterized by comprising the following steps:

[0022] (1) reacting 4-bromo-1H-pyrrole-2-carboxylic acid methyl ester and 6-ethoxy-3-pyridine boronic acid in the presence of a palladium catalyst and a base to obtain a compound with the following structural formula:

[0023]

[0024] (2) reacting the compound obtained in step (1) with a bromoalkane in the presence of a catalyst and a base to obtain a liquid room temperature phosphorescent organic compound; the bromoalkane is 1,4-dibromobutane or 1,6-dibromohexane.

[0025] The present application also provides an application of the liquid room temperature phosphorescent organic compound in information encryption technology and flexible optoelectronic devices.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] The present application designs organic molecules based on single ring donor-acceptor structure and different alkyl chain length, single ring donor (such as pyrrole, thiophene, benzene, etc.) and acceptor (such as pyridine, furan, etc.) are connected by single bond, the introduction of donor-acceptor structure and heteroatoms such as N and S etc. is conducive to intersystem crossing of exciton from singlet state to triplet state, thereby promoting the emission of triplet exciton phosphorescence; and the dihedral angle between donor and acceptor can rotate freely, thereby containing multiple conformations, by adjusting D and A structure, and adjusting the related linking group, various excitation state behaviors with adjustable luminous intensity and color are exhibited, thereby inhibiting the nucleation process of phosphorescent molecules and realizing adjustable phosphorescence. Moreover, the intermolecular van der Waals force between alkyl chains can adjust their molecular arrangement, thereby adjusting their aggregation and luminescence behavior. By precisely adjusting the van der Waals force, the phosphorescence emission of room temperature low viscosity liquid can be realized.

[0028] The organic compound of the present application exists in a liquid form at room temperature, realizes organic room temperature phosphorescence, has excellent processing performance and flexibility. The material has strong fluidity, the compatibility of the material makes the material easy to be mixed with other materials, and the material is easy to be filled in containers of various shapes and narrow spaces. The synthesis route of the present application, the required raw materials are cheap, have less impact on the environment and are easy to recycle, and the synthesis time is short, the yield is high, and a large amount of synthesis can be realized in a short time. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0030] Figure 1 is the fluorescence spectrum of the target product 1 in different polar solvents in example 1 of the present application;

[0031] Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the target product 1 in deuterated DMSO solution in example 1 of the present application;

[0032] Figure 3 is the storage modulus, loss modulus and complex viscosity curve of the target product 1 in example 1 of the present application;

[0033] Figure 4 is the fluorescence emission spectrum of the target product 1 in example 1 of the present application;

[0034] Figure 5 is the phosphorescence emission spectrum of the target product 1 in example 1 of the present application;

[0035] Figure 6is a physical photo of the target product 1 in Example 1 of the present application. DETAILED DESCRIPTION

[0036] For the purpose of understanding the present application, the present application will be described in further detail below with reference to the accompanying drawings and preferred embodiments, but the scope of the present application is not limited to the following specific embodiments.

[0037] Unless otherwise defined, all the professional terms used herein have the same meaning as understood by those skilled in the art. The professional terms used herein are only for the purpose of describing the specific embodiments and are not intended to limit the scope of the present application.

[0038] Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0039] The liquid room temperature phosphorescent organic compound of the present application has the following structural formula:

[0040]

[0041] Among them: monocyclic donor D can be selected from pyrrole, thiophene, benzene, preferably pyrrole.

[0042] Monocyclic acceptor A can be selected from pyridine, furan, preferably pyridine.

[0043] G1 and G2 can be independently selected from hydrogen, bromine, iodine, ester group, hydroxyl group, cyano group or alkoxy group. The ester group can be expressed as -COOR', wherein R' represents -C n H 2n+1 , n is a natural number, preferably 1≤n≤24, more preferably 1≤n≤18; the alkoxy group can be expressed as -OC x H 2x+1 , x is a natural number, preferably 1≤x≤24, more preferably 1≤x≤18. G1 is preferably an alkoxy group, more preferably -OC2H5. G2 is preferably an ester group, more preferably -COOCH3. G1 and G2 are preferably connected to the heterocycle.

[0044] Long carbon chain R1 can be expressed as C y H 2y L, L is halogen (L=F, Cl, Br, I), y is a natural number, preferably 1≤y≤24, more preferably 1≤y≤18, more preferably 4≤y≤6. L is preferably Br. R1 is preferably connected to the heterocycle.

[0045] Preferably, the liquid room temperature phosphorescent organic compound is selected from the following structural formula:

[0046] .

[0047] The method for preparing the liquid room temperature phosphorescent organic compound of the present application comprises the following steps:

[0048] (1) reacting 4-bromo-1H-pyrrole-2-carboxylic acid methyl ester and 6-ethoxy-3-pyridineboronic acid in the presence of a palladium catalyst and a base to obtain a compound with the following structural formula.

[0049]

[0050] In some embodiments, the palladium catalyst can be one of tetrakis(triphenylphosphine)palladium, palladium acetate, [1,1'-bis (di-tert-butylphosphino) ferrocene] dichloropalladium, tris(dibenzylideneacetone)dipalladium, [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium, [1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium dichloromethane complex, chloro(2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)[2-(2'-amino-1,1'-biphenyl)]palladium(II).

[0051] In some embodiments, the reaction solvent can be dioxane, toluene, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, acetonitrile, n-hexane.

[0052] In some embodiments, the base can be potassium carbonate, cesium carbonate, potassium phosphate, potassium bicarbonate, triethylamine, sodium hydroxide, potassium hydroxide.

[0053] In some embodiments, the reaction temperature is 80-100°C.

[0054] (2) reacting the compound obtained in step (1) with a bromoalkane in the presence of a catalyst and a base to obtain a liquid room temperature phosphorescent organic compound; the bromoalkane is 1,4-dibromobutane or 1,6-dibromohexane.

[0055] In some embodiments, the catalyst can be tetrabutylammonium bromide, etc.

[0056] In some embodiments, the base can be potassium carbonate, cesium carbonate, potassium phosphate, potassium bicarbonate, triethylamine, sodium hydroxide, potassium hydroxide.

[0057] In some embodiments, the reaction solvent can be dioxane, toluene, dimethyl sulfoxide, N,N-dimethylformamide, tetrahydrofuran, acetonitrile, n-hexane.

[0058] In some embodiments, the reaction temperature is 70-80°C.

[0059] The application designs a kind of liquid organic phosphorescent material containing single aromatic ring donor-acceptor and alkyl chain, and the emission of triplet exciton is promoted by the introduction of donor-acceptor structure and heteroatom, and the molecular arrangement of the alkyl chains can be adjusted by the intermolecular van der Waals force between the alkyl chains, and by accurately adjusting the van der Waals force, the phosphorescent emission of low viscosity liquid can be realized.

[0060] The compound of the application can be applied to the fields of information anti-counterfeiting, biological imaging and optoelectronic devices, etc. For example, in the application of information encryption technology, the liquid room temperature phosphorescent organic compound is uniformly coated on filter paper, a mask plate is placed above the filter paper and ultraviolet irradiation is continuously carried out, so that the information is recorded.

[0061] The synthesis method of the liquid room temperature phosphorescent organic material is illustrated by specific examples below. Specifically, the preparation of intermediates and target products is included, but these examples do not limit the application.

[0062] Example 1:

[0063] A liquid organic phosphorescent compound containing pyridine ring and pyrrole ring, and the specific structural formula is as follows:

[0064]

[0065] The preparation method is as follows:

[0066]

[0067] (1) Synthesis of compound A:

[0068] A certain amount of 4-bromo-1H-pyrrole-2-carboxylate (0.6 g, 2.93 mmol, 1 eq), 6-ethoxy-3-pyridine boronic acid (0.63 g, 3.82 mmol, 1.3 eq), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (0.11 g, 0.15 mmol, 0.05 eq), potassium carbonate (1.22 g, 8.81 mmol, 3 eq) were weighed into a 100 mL three-necked flask and 40 mL of dioxane was added, and the reaction mixture was refluxed at 90°C under argon atmosphere for 2 h. The reaction mixture was extracted with ethyl acetate and washed with deionized water. The obtained crude product was dried with anhydrous magnesium sulfate in ethyl acetate and condensed by rotary evaporation. Then, column chromatography was used for purification with ethyl acetate and petroleum ether as eluent, and 0.39 g of solid was obtained, with a yield of 51.8% (relative to the molar yield of 4-bromo-1H-pyrrole-2-carboxylate).

[0069] NMR of compound A:

[0070] 1H NMR (400 MHz, DMSO-d6, δ ppm) δ 12.07 (s, 1H, N-H), 8.40 (d, 1H,C-H), 7.90 (dd, J = 8.6, 1H, C-H), 7.47 (dd, 1H, C-H), 7.16 (t, 1H, C-H),6.71 (s, 1H, C-H), 4.25 (q, 2H, C-H), 3.75 (s, 3H, C-H), 1.28 (t, 3H, C-H).

[0071] (2) Synthesis of target compound 1:

[0072] Compound A (0.3 g, 1.22 mmol, 1 eq), 1,4-dibromobutane (2.63 g, 12.18 mmol, 10 eq), potassium carbonate (0.51 g, 3.65 mmol, 3 eq), tetrabutylammonium bromide (0.039 mmol, 0.12 mmol, 0.1 eq) and 30 mL of toluene were taken in a 250 mL round bottom flask and refluxed at 75 °C for 24 h. The reaction mixture was extracted with ethyl acetate and washed with deionized water. The crude obtained was dried over anhydrous magnesium sulfate in ethyl acetate and condensed by rotary evaporation. It was then purified by column chromatography using ethyl acetate and petroleum ether as eluents. The obtained material was taken in a rotary evaporator and evaporated at 30-40 °C to remove most of the eluents. The remaining liquid was then dried in a vacuum desiccator by oil pump at 35 °C for 12 h to remove the remaining eluents to obtain 0.34 g of liquid with 72.4% yield (molar yield).

[0073] NMR of target compound 1 Figure 2 is the proton nuclear magnetic resonance spectrum of target product 1 tested in deuterated DMSO solution using AVANCE III HD 400M nuclear magnetic resonance spectrometer:

[0074] 1H NMR (400 MHz, DMSO-d6, δ ppm) δ 8.37 (d, 1H, C-H), 7.86 (dd, 1H,C-H), 7.62 (s, 1H, C-H), 7.22 (s, 1H, C-H), 6.74 (d, 1H, C-H), 4.28 (dt, 4H,C-H), 3.75 (d, 3H, C-H), 3.5–3.46 (m, 2H, C-H), 1.87–1.70 (m, 4H, C-H), 1.33–1.25 (m, 3H, C-H).

[0075] 13C NMR (101 MHz, Chloroform-d) δ 162.53, 161.32, 143.15, 135.91, 124.64, 123.56, 122.44, 121.01, 115.00, 110.90, 61.79, 51.27, 48.42, 32.97, 30.25, 29.76, 14.72. HRMS (EI) (m / z): M calcd for [C17H21BrN2O3], 381.27; found, 381.195.

[0076] Figure 1 is the fluorescence spectrum of the target product 1 in Example 1 of the present application in different polar solvents at room temperature, normal pressure, using F-7000 fluorescence spectrophotometer at an excitation wavelength of 270 nm. As the polarity of the solvent increases, the emission wavelength red shifts, which embodies the typical intramolecular charge transfer characteristics; this characteristic is conducive to promoting the emission of room temperature phosphorescence and enhancing its intensity.

[0077] Figure 3 is the storage modulus G', loss modulus G'' and complex viscosity curve of the target product 1 in Example 1 of the present application. The test was carried out at room temperature, normal pressure, using a cone-plate mold in oscillation / dynamic mode using a German- NETZSCH-Kinexus Prime lab+ rheometer. It can be seen that the loss modulus is always greater than the storage modulus at low frequency (i.e. 100 (rad / s)), indicating that the target product 1 is a liquid substance, and the complex viscosity is always located at 3 Pa·s, indicating that the target product 1 is a low-viscosity liquid substance.

[0078] Figure 4 is the fluorescence emission spectrum of the target product 1 in Example 1 of the present application tested using F-4600 fluorescence spectrophotometer at room temperature, normal pressure, indicating that the fluorescence emission wavelength of the target product 1 is located at 425 nm.

[0079] Figure 5 is the phosphorescence emission spectrum of the target product 1 in Example 1 of the present application tested using F-4600 fluorescence spectrophotometer at room temperature, normal pressure, indicating that the phosphorescence emission wavelength of the target product 1 is located at 485 nm. The upper blue square is the fluorescence image emitted by the substance under the irradiation of a 365 nm ultraviolet lamp, and the upper yellow square refers to the afterglow image emitted after the ultraviolet lamp is turned off.

[0080] Figure 6 is the actual photo of the target product 1 in Example 1 of the present application. It can be coated on an elastic matrix to realize a flexible light source with stable brightness when bending, solving the problem of easy cracking of solid materials when bending.

[0081] Example 2:

[0082] A liquid organic compound containing pyridine ring and pyrrole ring, its specific structural formula is as follows:

[0083]

[0084] The preparation method is as follows:

[0085]

[0086] (1) Synthesis of compound A:

[0087] Weigh 4-bromo-1H-pyrrole-2-carboxylic acid methyl ester (0.6 g, 2.93 mmol, 1 eq), 6-ethoxy-3-pyridine boronic acid (0.63 g, 3.82 mmol, 1.3 eq), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (0.11 g, 0.15 mmol, 0.05 eq), potassium carbonate (1.22 g, 8.81 mmol, 3 eq) in a 100 mL three-necked flask and add 40 mL of dioxane, under argon atmosphere 90 ℃ reflux for 2 h. The reaction mixture is extracted with ethyl acetate, washed with deionized water. The obtained crude product is dried with anhydrous magnesium sulfate in ethyl acetate, rotary evaporation condensation. Then use ethyl acetate and petroleum ether as eluent, purified by column chromatography, 0.39 g solid, yield 51.8%.

[0088] NMR of compound A:

[0089] 1H NMR (400 MHz, DMSO-d6, δ ppm) δ 12.07 (s, 1H, N-H), 8.40 (d, 1H,C-H), 7.90 (dd, J = 8.6, 1H, C-H), 7.47 (dd, 1H, C-H), 7.16 (t, 1H, C-H),6.71 (s, 1H, C-H), 4.25 (q, 2H, C-H), 3.75 (s, 3H, C-H), 1.28 (t, 3H, C-H).

[0090] (2) Synthesis of target product 2:

[0091] Compound A (0.3 g, 1.22 mmol, 1 eq), 1,6-dibromo hexane (2.97 g, 12.18 mmol, 10 eq), potassium carbonate (0.51 g, 3.65 mmol, 3 eq), tetrabutyl ammonium bromide (0.039 mmol, 0.12 mmol, 0.1 eq) and 30 mL of toluene were taken in a 250 mL round bottom flask and refluxed at 75 °C for 24 h. The reaction mixture was extracted with ethyl acetate and washed with DI water. The crude obtained was dried over anhydrous magnesium sulfate and condensed by rotary evaporation. The obtained material was purified by column chromatography using ethyl acetate and petroleum ether as eluents and the obtained liquid was rotary evaporated at 30-40 °C after removing most of the eluents and then dried in a vacuum oven at 35 °C for 12 h by oil pump to remove the remaining eluents to obtain 0.38 g of liquid with 75.3% yield.

[0092] NMR of the target product 2:

[0093] 1H NMR (400 MHz, DMSO-d6) δ 8.35 (d, 1H, C-H), 7.84 (dd, 1H, C-H),7.59 (d, 1H, C-H), 7.20 (d, 1H, C-H), 6.72 (d, 1H, C-H), 4.25 (q, 4H, C-H),3.73 (s, 2H, C-H), 3.46 (t, 2H, C-H), 1.71 (dh, 4H, C-H), 1.37 (t, 1H, C-H),1.38–1.27 (m, 2H, C-H), 1.29–1.16 (m, 3H, C-H), 1.22 (s, 2H, C-H).

[0094] 13C NMR (101 MHz, DMSO-d6) δ 162.10, 161.00, 143.11, 136.16, 126.64,123.96, 122.01, 120.16, 114.66, 110.96, 61.53, 51.49, 48.83, 35.45, 32.59,31.33, 27.54, 25.57, 15.01.HRMS (EI) (m / z): M calcd for [C19H25BrN2O3],409.32; found, 409.206.

[0095] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. Therefore, any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application, without departing from the technical scheme of the present application, shall fall within the protection scope of the technical scheme of the present application.

Claims

1. A liquid room temperature phosphorescent organic compound characterized in that, which is selected from the following structural formula: 。 2. A method of producing the liquid room temperature phosphorescent organic compound according to claim 1, characterized by, comprising the following steps: (1) reacting 4-bromo-1H-pyrrole-2-carboxylic acid methyl ester and 6-ethoxy-3-pyridineboronic acid in the presence of a palladium catalyst and a base to obtain a compound of the following structural formula: (2) reacting the compound obtained in step (1) with a bromoalkane in the presence of a catalyst and a base to obtain the liquid room-temperature phosphorescent organic compound; the bromoalkane is 1,4-dibromobutane or 1,6-dibromohexane.

3. Use of the liquid room-temperature phosphorescent organic compound of claim 1 in information encryption technology, flexible optoelectronic devices.

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