Alkynyl Au (I) organic complex containing pyrazinoimidazole carbene ligand and preparation method and application thereof

Abstract

The present invention discloses an alkynyl Au (I) organic complex containing a pyrazinoimidazole carbene ligand, and a preparation method and application thereof. The alkynyl Au (I) organic complex is shown in the following formula I, wherein R1 and R2 are independently selected from one or more of an alkyl group, an alkyl substituted or unsubstituted aromatic group; R1 and R2 are the same or different; and R3 is selected from one or more of a phenyl group, an aromatic amine group, an aromatic ether group or an aromatic boron group. The alkynyl Au complex can exhibit TADF properties, can be used in the preparation of OLED devices or bioimaging materials, and exhibits a high electroluminescent efficiency; #imgabs0#

Description

Technical Field

[0001] The present invention relates to the technical field of luminescent materials, and more specifically to an alkynyl Au (I) organic complex containing a pyrazinoimidazole carbene ligand, and a preparation method and application thereof. Background Art

[0002] Luminescence mainly comes from excited state photons returning to the ground state through radiation transition, accompanied by fluorescence or phosphorescence. In organometallic complexes, luminescence is usually generated by charge transfer induced luminescence (ICT) between ligands within the molecule, or charge transfer induced luminescence (LLCT) between different ligands between molecules, and charge transfer transitions involving metals within or between molecules, such as metal-ligand charge transfer (MLCT), metal-metal-ligand charge transfer (MMLCT), and metal-metal charge transfer (MMCT). It is well known that the formation of excitons under electrical excitation usually produces 25% singlet excitons and 75% triplet excitons. Fluorescent materials are the first generation of OLED emitters. According to the spin coupling law, in fluorescent OLEDs, theoretically only 25% of singlet excitons can be used to generate light, and 75% of excitons in fluorescent materials are dissipated in the form of heat energy. Considering the 20% optical coupling effect of the device, the theoretical maximum external quantum efficiency is only 5%. These factors make the device efficiency of fluorescent OLEDs generally low. In order to increase the luminous efficiency of OLED, one of the important methods is to use the luminescence of triplet excitons to increase the luminous efficiency. By introducing heavy metals into organic luminescent materials to obtain complexes, the spin-orbit coupling effect is increased, so that the triplet excitons can successfully emit phosphorescence from the excited state. This method allows both triplet excitons and singlet excitons to be utilized to emit light, greatly increasing the luminous efficiency of the device. However, all these luminophores basically require the use of precious metals iridium or platinum. Since the reserves of these precious metals on the earth are limited and expensive, this greatly limits the large-scale production of OLEDs. Therefore, the third generation of OLED devices came into being, mainly through a new luminescence mechanism-thermally activated delayed fluorescence (TADF) to effectively utilize triplet excitons. TADF mainly reduces the energy difference between the triplet state and the singlet state, so that the triplet exciton can return to the singlet state through reverse intersystem crossing (RISC), and then return to the ground state from the singlet state through radiation transition accompanied by delayed fluorescence emission. At present, most organic molecules use the DA molecular system, which is conducive to the formation of charge transfer excited states, thereby achieving the purpose of small overlap between the molecular frontier orbitals HOMO-LUMO. In this way, the exchange energy of the molecule will become very small, and the energy difference between the lowest excited triplet state and the singlet state will also be small, which is conducive to the realization of TADF by the molecule. However, organic molecules have the problem of long emission lifetime, and are prone to deactivation of excited states, which reduces the luminescence efficiency. Summary of the invention

[0003] Based on the above problems, the first object of the present invention is to provide an alkynyl Au (I) organic complex containing a pyrazinoimidazole carbene ligand. The alkynyl Au (I) organic complex can exhibit TADF properties, and the spin-orbit coupling effect is enhanced, which increases the possibility of its triplet state decaying to ground state radiative phosphorescence, reduces the possibility of non-radiative transitions, and increases the luminous efficiency.

[0004] The second object of the present invention is to provide a method for preparing the above alkynyl Au(I) organic complex.

[0005] The third object of the present invention is to provide a use of the above alkynyl Au (I) organic complex in the preparation of OLED devices or bio-imaging materials.

[0006] In order to achieve the above first object, the present invention adopts the following technical scheme:

[0007] The present invention discloses an alkynyl Au (I) organic complex containing a pyrazinoimidazole carbene ligand, wherein the alkynyl Au (I) organic complex is shown in the following formula I:

[0008]

[0009] Wherein, R1 and R2 are each independently selected from one or more of alkyl, alkyl-substituted or unsubstituted aryl; R1 and R2 are the same or different;

[0010] R3 is selected from one or more of a phenyl group, an aromatic amine group, an aromatic ether group or an aromatic boron group.

[0011] The alkynyl Au(I) organic complex containing a pyrazinoimidazole carbene ligand provided by the present invention can exhibit TADF properties, and the spin-orbit coupling effect is enhanced, thereby increasing the possibility of its triplet state decaying to ground state radiative phosphorescence, reducing the possibility of non-radiative transitions, and increasing the luminescence efficiency. At the same time, by changing the steric hindrance of the acceptor part in the compound of formula I, different stacking modes can be obtained, and the luminescence properties of the compound of formula I can be regulated thereby.

[0012] The compound of formula I of the present invention can be regulated in the whole visible light region by changing the donor and the substituent of the donor itself while maintaining the carbene ligand, and the emission spectrum is red-shifted as the electron-donating performance of the donor or the substituent thereon is enhanced, which meets the requirements of the electronic effect. By increasing the electron-donating performance of the donor, the energy difference between HOMO-LUMO can be effectively reduced, thereby enhancing the luminescent wavelength and showing a red shift in the emission spectrum. At the same time, the system has a solvent color effect, showing a positive solvent effect in the emission spectrum and a negative solvent effect in the absorption spectrum. Since the ground state and the excited state dipoles are in opposite directions, the stabilizing effect of the polar solvent on the ground state is shown in the absorption spectrum, but the opposite effect is shown in the emission spectrum.

[0013] Furthermore, the alkyl group is a straight-chain alkyl group or a branched-chain alkyl group having 1 to 6 carbon atoms; preferably, the aryl group is an aryl group having 6 to 12 carbon atoms.

[0014] Furthermore, the alkyl group is a straight-chain alkyl group or a branched-chain alkyl group having 1 to 3 carbon atoms.

[0015] Furthermore, R1 and R2 are each independently selected from methyl, ethyl, propyl, isopropyl, n-butyl, 1,3-dimethylphenyl or in The connection key.

[0016] Further, R3 is selected from phenyl, triphenylamine, phenylphenoxazine,

[0017] Further, the compound of formula I is selected from the following structures:

[0018]

[0019]

[0020] In order to achieve the above second purpose, the present invention adopts the following technical solutions:

[0021] The present invention discloses a method for preparing the above-mentioned alkynyl Au (I) organic complex, comprising the following steps:

[0022]

[0023] a) Compound Ia, compound R1-NH2 and compound R2-NH2 react to obtain compound Ib;

[0024] b) reacting compound Ib with triethyl orthoformate and concentrated hydrochloric acid to obtain compound Ic;

[0025] c) reacting compound Ic with tetrahydrothiophene gold chloride to obtain compound I-1;

[0026] d) reflux the compound I-1 and the compound I-2 under alkaline conditions to obtain the compound of formula I.

[0027] Furthermore, in step a), the molar ratio of compound Ia, R1-NH2 and R2-NH2 is 1:1.2-1.5:1.2-1.5; preferably, the reaction temperature is 120-140°C, and the reaction time is 6-10h.

[0028] Furthermore, in step b), the mass volume ratio of compound Ib to triethyl orthoformate is 0.75-3 g:10 ml; preferably, the reaction temperature is 120-140° C., and the reaction time is 6-10 h.

[0029] Furthermore, in step c), the molar ratio of compound Ic to tetrahydrothiophene gold chloride is 1:1.2-1.5; preferably, the reaction temperature is 25-40° C., and the reaction time is 6-12 h.

[0030] Furthermore, in step d), the molar ratio of compound I-1 to compound I-2 is 1:1; preferably, the reaction time is 6-12 hours.

[0031] In order to achieve the third objective, the present invention discloses a method for using the alkynyl Au (I) organic complex as described above in the preparation of OLED devices or biological imaging materials.

[0032] The beneficial effects of the present invention are as follows:

[0033] The present invention discloses an alkynyl Au (I) organic complex containing a pyrazinoimidazole carbene ligand, a preparation method and application thereof. In the present invention, the alkynyl Au (I) organic complex has the following advantages:

[0034] 1) The alkynyl Au(I) organic complex provided by the present invention can exhibit TADF properties, increase the possibility of its triplet state decaying to ground state radiative phosphorescence, reduce the possibility of non-radiative transitions, and increase the luminescence efficiency. It can be used to prepare OLED devices or bio-imaging materials and exhibit high electroluminescence efficiency.

[0035] 2) The alkynyl Au(I) organic complex provided by the present invention can obtain different stacking modes by changing the size of the receptor part steric hindrance in the compound of formula I, and thereby regulate the luminescence properties of the compound of formula I, realizing the room temperature phosphorescence of MLCT and LE involving the metal d orbital and the delayed fluorescence induced by intramolecular charge transfer.

[0036] 3) The alkynyl Au(I) organic complex provided by the present invention can be regulated within the entire visible light region by changing the donor and the substituents of the donor itself while maintaining the carbene ligand, and the emission spectrum red-shifts as the electron donating performance of the donor or the substituents thereon is enhanced, which meets the requirements of the electronic effect. By increasing the electron donating performance of the donor, the energy difference between HOMO-LUMO can be effectively reduced, thereby enhancing the luminescent wavelength and the emission spectrum showing a red shift. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0038] Figure 1 The absorption spectra and emission spectra of the compounds 2, 4, 6, and 8 synthesized in the examples are shown in toluene solution;

[0039] Among them, a is the absorption spectrum and b is the emission spectrum.

[0040] Figure 2 The absorption spectrum and emission spectrum of compound 4 synthesized in Example 7 in different solutions are shown;

[0041] Among them, a is the absorption spectrum and b is the emission spectrum.

[0042] Figure 3 The emission spectra of the powders of compounds 2, 4, 6, and 8 synthesized in the examples and the emission spectra in the state of 5% PMMA films are shown;

[0043] Wherein, a is the emission spectrum of the compound powder, and b is the emission spectrum in the state of 5% PMMA film.

[0044] Figure 4 The lifetime curves of compounds 2, 4, 6, and 8 synthesized in the examples in toluene solution and the lifetime temperature curve of compound 2 are shown;

[0045] Among them, a is the lifetime curve of compounds 2, 4, 6, and 8 in toluene solution; b is the lifetime temperature curve of compound 4 in the state of 5% PMMA film.

[0046] Figure 5 The electroluminescent properties of compounds 4 and 8 synthesized in the examples are shown;

[0047] Among them: a is the electroluminescence spectrum, b is the external quantum efficiency of luminescence, c is the relationship between current density and brightness and voltage, and d is the relationship between current density and power efficiency and brightness. DETAILED DESCRIPTION

[0048] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and drawings. It should be clear that the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0050] In the following examples, "low temperature" refers to 77K.

[0051] Example 1

[0052] Preparation of methyl substituted carbene compound A1, preparation route a is as follows:

[0053]

[0054] 1) 2,3-dichloropyrazine (0.26 g, 4.10 mmol) and methylamine (33% aqueous solution, 14 ml) were stirred and added into a 25 ml reactor. The reactor was then placed in an oven at 140°C for 10 hours and then placed in a refrigerator for crystallization to obtain 2,3-dimethylaminopyrazine as a yellow-green needle-shaped solid (2.51 g, yield: 90%).

[0055] 2) Mix 2,3-dimethylaminopyrazine (2.51 g, 18 mmol), triethyl orthoformate (10 ml) and 37% concentrated hydrochloric acid (1 ml) at 120°C and reflux. The reaction endpoint is detected by TLC. The mixture is cooled to room temperature and 50 ml of ether is added to crystallize. The solid is collected by filtration and decolorized by stirring with 20 ml of ethanol and activated carbon (5 g). The filtrate is dried by rotary evaporation and the solid is recrystallized in methanol / ether (volume ratio 1:10) to obtain a yellow solid 1,3-dimethylpyrazine imidazole chloride (1.56 g, yield: 47%).

[0056] 3) Dichloromethane (40 ml) and ethanol (20 ml) were added to 1,3-dimethylpyrazine imidazole chloride (108 mg, 0.60 mmol) and silver oxide (70 mg, 0.35 mmol), and the mixture was stirred for reaction for 12 h in the dark. After the reaction, the precipitate was filtered, and tetrahydrothiophene gold chloride (0.35 mmol) was added to the filtrate, and the mixture was reacted in the dark at room temperature for 6 h. The mixture was filtered, and the filtrate was dried to obtain a solid which was recrystallized with dichloromethane / ether solvent (volume ratio 1:10) to obtain a white solid A1, i.e. 1,3-dimethylpyrazine imidazole gold chloride (100 mg, yield: 75%).

[0057] Example 2

[0058] Preparation of phenyl substituted carbene compound A2, preparation route b is as follows:

[0059]

[0060] 1) 2,3-Dichloropyrazine (5 ml) and 3,5-dimethylaniline (12 ml) were refluxed at 140°C for 6 h to generate a solid. 50 ml of dichloromethane and 50 ml of distilled water were added to the solid and stirred for 2 h. The solid was then extracted with dichloromethane. After the solvent was dried, n-hexane was added to precipitate a solid (7 g, yield: 60%).

[0061] 2) The above solid (750 mg), 10 ml of triethyl orthoformate and 0.2 ml of concentrated hydrochloric acid were refluxed at 120° C. The reaction endpoint was detected by TLC. The mixture was cooled to room temperature and n-hexane was added to precipitate a solid. The solid was filtered to obtain a solid (550 mg, yield: 60%).

[0062] 3) The above solid (100 mg) was reacted with 40 mg of cuprous chloride in 15 ml of dry tetrahydrofuran solution at 60° C. The reaction endpoint was detected by TLC, and the mixture was filtered. 30 ml of dichloromethane and 30 mg of tetrahydrothiophene gold chloride were added to the filtered solid, and the mixture was refluxed at 40° C. for 6 h. The filtrate was filtered to dryness, 3 ml of dichloromethane was added to dissolve the solid, and the solid was recrystallized with 10 ml of petroleum ether. The white solid A2 was obtained by filtration.

[0063] Example 3

[0064] Benzyne B1 and triphenylamine alkyne B2 are both commercially available products. The preparation of phenoxazine benzyne compound B3, benzophenoxazine benzyne compound B4 and compound B5 is shown in the following route:

[0065]

[0066] The preparation process of B3 is as follows:

[0067] 1) Phenoxazine (10 mmol), p-bromoiodobenzene (15 mmol), cuprous iodide (1 mmol), L-proline (1.1 mmol), and potassium carbonate (10 mmol) were added to 30 ml of DMF solution and reacted at 160° C. The reaction endpoint was monitored by TLC, and the filtrate was filtered to obtain a filtrate. The filtrate was spin-dried and then subjected to column chromatography (developing solvent: CH2Cl2: petroleum ether = 1:10) to obtain a white solid;

[0068] 2) The above solid (2 mmol), Pd(PPh3)2Cl2 (0.08 mmol), cuprous iodide (0.04 mmol), and trimethylsilylacetylene (4 mmol) were added to 40 mL of triethylamine, heated to reflux, and the reaction endpoint was monitored by TLC. The filtrate was filtered to obtain a filtrate, which was then dried and separated by column chromatography (developing solvent: CH2Cl2: petroleum ether = 1:10) to obtain a solid;

[0069] 3) The above solid (1 mmol) and K2CO3 (5 mmol) were added to 40 ml of methanol solution, stirred at room temperature for 3 hours, and then the solvent was removed. The mixture was extracted with dichloromethane and the solvent was dried by spin drying to obtain compound B3.

[0070]

[0071] The preparation process of B4 is as follows:

[0072] 1) Add o-phenyl iodine methyl ether (10 mol), bromodifluoroaniline (5 mmol), potassium carbonate (20 mmol), and copper powder (10 mmol) to 100 ml of o-dichlorobenzene solution, react at 180° C. for 120 hours, filter and concentrate the liquid, and add n-hexane to precipitate a solid;

[0073] 2) The above solid (5 mmol) was dissolved in dichloromethane, and boron tribromide (10.6 mmol) was added at low temperature, and stirred for 3 hours. Then the reaction mixture was poured into water, extracted with dichloromethane, and the solvent was dried to obtain a solid;

[0074] 3) Add the above solid (1 mmol) and potassium carbonate (3 mmol) into 20 ml DMF solution, react at 100° C. for 12 hours, add water to precipitate solid, and filter to obtain the solid;

[0075] 4) The above solid (2 mmol), Pd(PPh3)2Cl2 (0.08 mmol), cuprous iodide (0.04 mmol), and trimethylsilylacetylene (4 mmol) were added to 40 mL of triethylamine, heated to reflux, and the reaction endpoint was monitored by TLC. The filtrate was filtered to obtain a filtrate, which was then dried and separated by column chromatography (developing solvent: CH2Cl2: petroleum ether = 1:10) to obtain a solid.

[0076] 5) The above solid (1 mmol) and K2CO3 (5 mmol) were added to 40 ml of methanol solution, stirred at room temperature for 3 hours, and then the solvent was removed. The mixture was extracted with dichloromethane and the solvent was dried by spin drying to obtain compound B4.

[0077]

[0078] B5 preparation process:

[0079] 1) Add methoxy-isophenylene ether (10 mmol), bromodifluoroaniline (10 mmol), potassium carbonate (20 mmol), and copper powder (10 mmol) to 100 ml of o-dichlorobenzene solution, react at 180° C. for 120 hours, filter and concentrate the liquid, and add n-hexane to precipitate a solid.

[0080] 2) The above solid (1 mmol) and potassium carbonate (3 mmol) were added to 20 ml of DMF solution, and reacted at 100° C. for 12 hours. Water was added to precipitate a solid, which was filtered to obtain a solid.

[0081] 3) The above solid (2 mmol), Pd(PPh3)2Cl2 (0.08 mmol), cuprous iodide (0.04 mmol), and trimethylsilylacetylene (4 mmol) were added to 40 mL of triethylamine, heated to reflux, and the reaction endpoint was monitored by TLC. The filtrate was filtered to obtain a filtrate, which was then dried and separated by column chromatography (developing solvent CH2Cl2: petroleum ether = 1:10) to obtain a solid.

[0082] 4) The above solid (1 mmol) and K2CO3 (5 mmol) were added to 40 ml of methanol solution, stirred at room temperature for 3 hours, and then the solvent was removed. After extraction with dichloromethane, the solvent was dried and compound B5 was obtained.

[0083]

[0084] B6 preparation process:

[0085] 1) Add 2,6-difluoro-4-bromoiodobenzene (12.5 mmol), phenol (37.6 mmol) and K2CO3 (37.6 mmol) to 50 ml N-methylpyrrolidone solution, react at 200°C for 24 hours under nitrogen atmosphere. Pour into ice water and filter to obtain a precipitate, extract the precipitate with toluene, and spin dry to obtain a white solid.

[0086] 2) Under nitrogen atmosphere, n-butyl lithium hexane solution (1.6M, 18.7mmol) was added dropwise to a solution of the above solid (17.0mmol) in o-dichlorobenzene (300mL). Stir at room temperature for 3 hours, and slowly add BBr3 (20.4mmol) under low temperature. Then the reaction mixture was warmed to room temperature and stirred for 2 hours. After adding ultra-dry i-Pr2NEt (34.0mmol), the mixture was further stirred at 180°C for 12 hours. The solvent was removed by distillation under reduced pressure, and CH2Cl2 was extracted. After being spin-dried, it was purified by silica gel column chromatography (eluent dichloromethane: petroleum ether = 1:10) to obtain a white solid.

[0087] 3) The above solid (2 mmol), Pd(PPh3)2Cl2 (0.08 mmol), cuprous iodide (0.04 mmol), and trimethylsilylacetylene (4 mmol) were added to 40 mL of triethylamine, heated to reflux, and the reaction endpoint was monitored by TLC. The filtrate was filtered to obtain a filtrate, which was then spin-dried and separated by column chromatography (developing solvent CH2Cl2: petroleum ether = 1:10) to obtain a solid.

[0088] 4) The above solid (1 mmol) and K2CO3 (5 mmol) were added to 40 ml of methanol solution, stirred at room temperature for 3 hours, and then the solvent was removed. The mixture was extracted with dichloromethane and the solvent was dried by spin drying to obtain compound B4.

[0089] Example 4

[0090] This example prepares compound 1

[0091]

[0092] The preparation process is as follows: phenylacetylene (1 mmol), carbene gold chloride (1 mmol) and sodium hydroxide (7 mmol) are added to a methanol solution and heated under reflux for 12 hours. After the reaction is completed, the solution is cooled to room temperature, the solvent is removed by vacuum distillation, and the solid is extracted with dichloromethane and concentrated to obtain a solid. Compound 1 is obtained by recrystallization with dichloromethane / methanol (volume ratio 1:8).

[0093] 1 H NMR (400MHz, CDCl3) δ8.54(s,2H),7.25–7.08(m,5H),4.06(s,6H).

[0094] Example 5

[0095] This example prepares compound 2

[0096]

[0097] The method of Reference Example 4 was followed, except that Compound A1 was replaced by Compound A2.

[0098] 1 H NMR (400MHz, CDCl3) δ8.54(s,2H),7.40(s,6H),7.25–7.08(m,5H),2.46(s,12H).

[0099] Example 6

[0100] This example prepares compound 3

[0101]

[0102] The method of Reference Example 4 was followed, except that Compound B1 was replaced by Compound B2.

[0103] Example 7

[0104] This example prepares compound 4

[0105]

[0106] The method of Reference Example 5 was followed, except that Compound B1 was replaced by Compound B2.

[0107] 1 H NMR(400MHz,Chloroform-d)δ8.54(s,2H),7.40(s,4H),7.27(s,2H),7.24–7.17(m ,6H),7.04(d,J=8.1Hz,4H),6.98(t,J=7.2Hz,2H),6.92–6.85(m,2H),2.46(s,12H)

[0108] Example 8

[0109] This example prepares compound 5

[0110]

[0111] The method of Reference Example 4 was followed, except that Compound B1 was replaced by Compound B3.

[0112] Example 9

[0113] This example prepares compound 6

[0114]

[0115] The method of Reference Example 5 was followed, except that Compound B1 was replaced by Compound B3.

[0116] 1 H NMR(400MHz,Chloroform-d)δ8.56(s,2H),7.59(d,J=7.9Hz,2H),7.42(s,4H),7.23(s,2H),7.14(d ,J=7.5Hz,2H),6.63(t,J=10.7Hz,4H),6.56(t,J=8.3Hz,2H),5.89(d,J=7.7Hz,2H),2.48(s,12H).

[0117] Example 10

[0118] This example prepares compound 7

[0119]

[0120] The method of Reference Example 4 was followed, except that Compound B1 was replaced by Compound B4.

[0121] Embodiment 11

[0122] This example prepares compound 8

[0123]

[0124] The method of Reference Example 5 was followed, except that Compound B1 was replaced by Compound B4.

[0125] 1 H NMR (400MHz, Chloroform-d) δ8.58(s,2H),7.43(s,4H),7.31(d,J=13.6Hz,4H),6.92(d,J=14.9Hz,6H),6.59(s,2H),2.50(s,12H).

[0126] Example 12

[0127] This example prepares compound 11

[0128]

[0129] The method of Reference Example 4 was followed, except that Compound B1 was replaced by Compound B6.

[0130] Example 13

[0131] This example prepares compound 12

[0132]

[0133] The method of Reference Example 5 was followed, except that Compound B1 was replaced by Compound B6.

[0134] 1 H NMR (400MHz, Chloroform-d) δ8.58 (d, J = 7.7Hz 2H), 8.47 (d, J = 2.6Hz 2H), 7.62 (t, J = 8.0Hz, 2H), 7.48-7.21 (m, 10H), 7.06 (s, 2H), 2.43 (s, 12H).

[0135] With reference to the above method, the present invention also prepared the following compounds:

[0136]

[0137] Embodiment 14

[0138] In order to compare how the stacking mode can be changed by changing the substituents of different acceptors under the same donor to achieve the regulation of luminescence properties, compounds 3 and 4 are compared. Since the methyl-substituted carbene compound 4 has less steric hindrance than the phenyl-substituted carbene compound 3, its stacking is more serious, which is manifested as a decrease in solubility. The enhanced stacking will lead to enhanced interactions between the molecules of compound 3. At the same time, the stacking will change through external forces, reducing the distance between the metals, thereby enhancing the interaction between the metals to achieve the regulation of luminescence properties. Figure 2 In b, we can see that as the polarity of the solvent increases, the luminescence red-shifts, which manifests as delayed fluorescence of LLCT (ligand-to-ligand charge transfer). The luminescence performance data indicate that the two compounds can be used to prepare OLED devices.

[0139] Embodiment 15

[0140] Compounds 1-14 prepared in the examples realize the construction of a donor-acceptor structure, so that the energy difference between the singlet state and the triplet state of such compounds is less than 0.1 eV, thereby realizing that the triplet exciton returns to the singlet exciton through reverse intersystem crossing, and then returns to the ground state through the singlet state through radiative transition, accompanied by delayed fluorescence emission, making good use of the triplet exciton, and the short lifetime can effectively reduce the roll-off efficiency. Therefore, compounds 3-14 have TADF properties, and their properties are manifested in a significant increase in the luminescence lifetime at low temperatures, such as Figure 4 shown. Figure 4 b is the data of the lifetime variation with temperature of compound 4, which can be well fitted to satisfy the formula It can be well proved that the obtained compound 3-14 does have TADF, so it can be used to prepare OLED devices. At the same time, by modifying the donor part of the molecule, it can also achieve emission in the full wavelength range of the visible light region. If the electron donating ability of the donor part is increased, its emission spectrum can be red-shifted. Different luminescent positions can obtain OLED devices with different chromaticities. However, since the electron donating ability of the donor of compounds 1 and 2 is not strong, the excited state is mainly phosphorescent with LE (local excited state) and MLCT (metal to ligand charge transfer), which can be reflected from the absorption spectrum and emission spectrum (emission peak of vibration structure).

[0141] Table 1 Photophysical data of compounds 2, 4, 6, 8 in solid films and solutions

[0142]

[0143] Example 16

[0144] The compound 4 synthesized in Example 7 and the compound 8 synthesized in Example 11 were used as the luminescent host materials to prepare an electroluminescent device, which includes an anode layer, a hole transport layer, a luminescent layer, an electron transport layer and a cathode layer sequentially arranged on a glass substrate from bottom to top;

[0145] The structure of the device is: ITO / PEDOT:PSS (40nm) / 10wt% Compound 4:90wt% TCTA (40nm) / TmPyPB (45nm) / LiF (1nm) / Al (100nm). The maximum external quantum efficiency is 20.4%.

[0146] Electroluminescent properties such as Figure 5 As shown, the data are summarized in Table 2. The maximum emission peak of the bright green light emitted by the device is at 520-550 nm, which is consistent with the photoluminescence spectrum of the luminescent host material. The International Commission on Illumination (CIE) coordinates are (0.32, 0.54) and (0.40, 0.56). The maximum EQE, current efficiency (CE) and power efficiency (PE) of device A were recorded as 20%, 62.8 cd / A and 52.9 lm / W, respectively. It is worth noting that it is compared with the best Au(III) OLEDs among solution-processed OLEDs, and the performance of this device is at a high level. The EQE of device B max The CE and PE values ​​are also relatively low at 14.9%. In addition, both devices have a 1000cd / m 2 The EQE at high brightness decreases to 9.7% and 8.5%, respectively, corresponding to an efficiency roll-off of 6.4%-10.3%.

[0147] Table 2 Electroluminescent performance data of compound 4 and compound 8

[0148]

[0149]

[0150] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. An alkynyl Au(I) organic complex comprising a pyrazinoimidazole carbene ligand, characterized in that: The alkynyl Au (I) organic complex is shown in the following formula I: Wherein, R1 and R2 are each independently selected from methyl, ethyl, propyl, isopropyl, n-butyl, 1,3-dimethylphenyl or in is a connecting bond; R1 and R2 are the same or different; R3 is selected from triphenylamine, phenylphenoxazine, 2. The alkynyl Au (I) organic complex according to claim 1, characterized in that The compound of formula I is selected from the following structures:

3. A method for preparing an alkynyl Au (I) organic complex as claimed in any one of claims 1 to 2, characterized in that: The steps include: a) Compound Ia, compound R1-NH2 and compound R2-NH2 react to obtain compound Ib; b) reacting compound Ib with triethyl orthoformate and concentrated hydrochloric acid to obtain compound Ic; c) reacting compound Ic with tetrahydrothiophene gold chloride to obtain compound I-1; d) reflux the compound I-1 and the compound I-2 under alkaline conditions to obtain the compound of formula I.

4. The preparation method according to claim 3, characterized in that: The molar ratio of compound Ia, R1-NH2 and R2-NH2 in step a) is 1:1.2-1.5:1.2-1.

5.

5. The preparation method according to claim 3, characterized in that: The reaction temperature is 120-140°C and the reaction time is 6-10h.

6. The preparation method according to claim 3, characterized in that: The mass volume ratio of compound Ib and triethyl orthoformate in step b) is 0.75-3g:10ml.

7. The preparation method according to claim 3, characterized in that: The reaction temperature is 120-140°C and the reaction time is 6-10h.

8. The preparation method according to claim 3, characterized in that: In step c), the molar ratio of compound Ic to tetrahydrothiophene gold chloride is 1:1.2-1.

5.

9. The preparation method according to claim 3, characterized in that: The reaction temperature is 25-40°C and the reaction time is 6-12h.

10. The preparation method according to claim 3, characterized in that: In step d), the molar ratio of compound I-1 to compound I-2 is 1:

1.

11. The preparation method according to claim 3, characterized in that: The reaction time is 6-12h.

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