Azazulene-containing large conjugated heteroaryl complex as well as preparation method and application thereof

Abstract

The invention relates to an azaazulene-containing large conjugated heteroaryl complex and a preparation method and application thereof, and the method comprises the following steps: mixing an azaazulene precursor and a benzene precursor, carrying out a coupling reaction, mixing an azaazulene intermediate obtained by the coupling reaction with a coordination center, and carrying out a coordination reaction to obtain the azaazulene-containing large conjugated heteroaryl complex. The azaazulene-containing large conjugate heteroaryl complex is obtained. Compared with the prior art, the invention has the characteristics of large molar absorption coefficient, large Stokes shift and large red shift of absorption emission peak, and shows bright fluorescence characteristic.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic technology, and relates to a large-conjugated heteroaryl complex containing nitrogen heteroazulene, a preparation method thereof, and an application thereof. Background Art

[0002] Azulene is a blue-colored, non-alternant conjugated non-benzenoid aromatic compound, which is an isomer of naphthalene. Azulene is formed by the fusion of a five-membered ring cyclopentadiene and a seven-membered ring cycloheptatriene. Through intramolecular resonance, azulene forms a structure with a formally negatively charged five-membered ring and a positively charged seven-membered ring, so it has a relatively large intramolecular dipole moment (1.08 D). As a typical non-alternant fused-ring aromatic hydrocarbon, due to its unique physical and chemical properties, azulene and its derivatives exhibit different electronic structures and properties, and are promising candidates for constructing advanced organic materials, and have received more and more extensive attention. In recent years, azulene-based materials have been widely studied in organic field effect transistors (OFETs), solar cells and other related fields. However, there are relatively few studies on the luminescence properties of azulene. The asymmetry of the frontier molecular orbitals (FMOs) of azulene reduces the repulsion between unpaired electrons, resulting in a narrow energy gap between its ground state (S0) and the first excited state (S1). This narrow energy gap causes an S0→S1 transition absorption band in the visible light region, showing a characteristic blue color. In addition, the significant energy difference between S1 and S2 (ΔE(S2 - S1)>10000 cm -1 ) and orbital asymmetry slow down the non-radiative S2→S1 transition, while enhancing the radiative S2→S0 transition, thus showing anti-Kasha fluorescence behavior. However, this unique photophysical property also confines the fluorescence of azulene and its derivatives to the short-wavelength region, and the oscillation intensity of the radiative transition from S2 to S0 is relatively low, resulting in a very weak spectrum of azulene. In order to explore the luminescence properties of azulene, scientists have found that protonation and doping can significantly enhance the fluorescence intensity of azulene. Although protonated azulene exhibits appreciable fluorescence, the protonation behavior also changes the planar structure and impairs the electron transport performance. In terms of doping, previous studies (Xin, H., et al., Azulene-Based BN-Heteroaromatics. The Journal of Organic Chemistry, 2019. 85(1): p.70 - 78.) introduced boron and nitrogen into the extended structure of azulene, thereby improving the fluorescence performance, but the improvement ability is limited, and the photoluminescence quantum yield (PLQY) is increased to 0.5%.

[0003] Patent CN107011213A provides a multi-channel luminescent fluorescent probe of an azulenyl group-containing α-cyanostyrene derivative, its preparation method and application. It provides derivatives containing azulene-cyanostyrene. The compound has various luminescent properties. After the action of acid or light, the fluorescence is significantly enhanced. It has three luminescent states: upconversion, near-infrared, and visible, and can be used as an excellent multi-channel detection fluorescent probe for fluorescence labeling or fluorescence detection in water, soil, and organisms. However, in this patent, the fluorescence based on azulene is generated after protonation with an acid solution, rather than the direct luminescence of its azulene derivatives.

[0004] Patent US6885026B1 discloses an electroluminescent device, which includes a light-emitting layer containing a boron complex, where boron is connected to the nitrogen atoms of a 6-membered heteroaromatic ring group and a 5-membered heteroaromatic ring group, and the 5- and 6-membered heteroaromatic ring groups are further connected through a methylene bridge. In addition, the 5-membered heteroaromatic ring contains at least one divalent or trivalent heteroatom; the Inv-2 structure is a complex formed by coupling 2-bromo-quinoline and benzothiazole acetonitrile and then coordinating and complexing with boron trifluoride diethyl ether. However, this patent uses quinoline as a precursor, and the absorption peak and emission peak are shifted to the blue. Summary of the Invention

[0005] The purpose of the present invention is to overcome at least one defect of the above-mentioned existing technologies and provide a nitrogen-containing heteroazulene large-conjugated heteroaryl complex, its preparation method and application. The present invention has the characteristics of large molar extinction coefficient, large Stokes shift, and significant red shift of absorption and emission peaks, showing bright fluorescence characteristics.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a nitrogen-containing heteroazulene large-conjugated heteroaryl complex, and the structural formula of the complex is selected from formula (Ⅰ), formula (Ⅱ) or formula (Ⅲ),

[0008]

[0009] wherein, M is selected from a beryllium atom, a zinc atom, a copper atom or an iridium atom, R1 is selected from a hydrogen atom, a deuterium atom, a methyl group, a methoxy group or a tert-butyl group, and R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a hydroxyl group, a cyano group, a methyl group, a methoxy group, a tert-butyl group or a halogen atom.

[0010] As a preferred technical solution, M is selected from a beryllium atom or a zinc atom, R1 is selected from a hydrogen atom, a deuterium atom, a methoxy group or a tert-butyl group, and R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a methyl group, a methoxy group or a bromine atom.

[0011] In the present invention, a carbon atom in the azulene five-membered ring is replaced by a nitrogen atom to form 1-azaazulene, which leads to significant changes in various properties. Due to the relatively high electronegativity of nitrogen, the nitrogen atom attracts the surrounding electrons, resulting in the rearrangement of the π electron cloud density and the enhancement of the conjugation effect. Although 1-azaazulene retains the asymmetry of the frontier orbitals, its S0-S1 energy gap is significantly larger than that of azulene. Notably, the decrease in the S2-S1 energy difference accelerates the non-radiative S2→S1 transition, thereby effectively suppressing the anti-Kasha S2→S0 radiative transition. These changes in the electronic structure and frontier orbital energy levels make 1-azaazulene an ideal framework for designing fluorescent materials that comply with Kasha's rule and exhibit red-shifted emission. This modification promotes electronic transitions and enhances the luminescence efficiency.

[0012] Metal complexes and boron difluoride complexes are important luminescent materials nowadays. At the same time, the lone pair electrons of the nitrogen atom in 1-azaazulene can participate in effective coordination, making it an ideal ligand for constructing complexes. Therefore, in the present invention, a series of large-conjugated fused heteroaryl complexes containing azaazulene were synthesized. Through the coupling reaction of azaazulene precursor 1 with different benzene precursors 2, 3, and 4, azaazulene intermediates I-1, II-1, and III-1 were generated, and then, through the participation of the lone pair electrons of nitrogen in coordination, the final products, large-conjugated heteroaryl complexes I, II, and III containing azaazulene, were synthesized. Among them, complex I is a metal complex containing azaazulene; complexes II and III have a BODIPY-like structure containing azaazulene. Among them, complex III is a BODIPY-like compound containing bilateral azaazulene synthesized through the bilateral thiophene of the precursor. All three types of complexes are fused heteroaryl complexes with large conjugation, and at the same time, they have varying degrees of fluorescence enhancement compared to traditional azulene derivatives.

[0013] In the present invention, benzene precursors 2, 3, and 4 can all undergo coupling reactions with azaazulene precursor 1 to form azaazulene intermediates that can undergo keto-enol tautomerism, and then the subsequent synthesis of large-conjugated heteroaryl complexes can be carried out. Among them, the oxygen atom in the hydroxyl group of benzene precursor 2 can improve the stability and optoelectronic properties of the subsequent complexes through strong coordination effects, electronic regulation, and functional design; the five-membered ring in benzene precursor 3 can obtain a molecule with a BODIPY-like structure after coupling and subsequent coordination, and the strong electron-withdrawing effect of the cyano group elongates the π-π * transition wavelength through conjugation, realizing the red shift of the absorption and emission spectra; benzene precursor 4 is a bilateral thiazole system, which improves the molecular symmetry compared to the asymmetric structure of benzene precursor 3, realizes a further red shift of the absorption and emission spectra, and further improves the conjugation degree of the molecule.

[0014] One of the technical solutions of the present invention is to provide a preparation method of the large-conjugated heteroaryl complex containing azaazulene, and this method includes the following steps:

[0015] Mix an azepine precursor and a benzene precursor, carry out a coupling reaction, mix the azepine intermediate obtained from the coupling reaction and a coordination center, and carry out a coordination reaction to obtain a large conjugated heteroaryl complex containing azepine.

[0016] Furthermore, the structural formula of the azepine precursor is formula (1),

[0017]

[0018] wherein, R1 is selected from a hydrogen atom, a deuterium atom, a methyl group, a methoxy group or a tert-butyl group, and X is a halogen atom;

[0019] The structural formula of the benzene precursor is selected from formula (2), formula (3) or formula (4),

[0020]

[0021] wherein, R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a hydroxyl group, a cyano group, a methyl group, a methoxy group, a tert-butyl group or a halogen atom, and R5 is selected from a boronic acid group or a borate group;

[0022] The structural formula of the azepine intermediate is selected from formula (Ⅰ-1), formula (Ⅱ-1) or formula (Ⅲ-1),

[0023]

[0024] wherein, R1 is selected from a hydrogen atom, a deuterium atom, a methyl group, a methoxy group or a tert-butyl group, and R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a hydroxyl group, a cyano group, a methyl group, a methoxy group, a tert-butyl group or a halogen atom;

[0025] The coordination center is selected from a metal coordination center or a disubstituted boron coordination center.

[0026] As a preferred technical solution, R1 is selected from a hydrogen atom, a deuterium atom, a methoxy group or a tert-butyl group, and R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a methyl group, a methoxy group or a bromine atom.

[0027] The reaction equation of the coupling reaction is selected from one of the following formulas:

[0028]

[0029]

[0030] The reaction equation of the coordination reaction is selected from one of the following formulas:

[0031]

[0032] When the structural formula of the benzene precursor adopts Formula (2), the structural formula of the azapentalene intermediate adopts Formula (I-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene adopts the metal complex formula (I) of azapentalene, the coordination center adopts a metal coordination center.

[0033] When the structural formula of the benzene precursor is selected from Formula (3) or Formula (4), the structural formula of the azapentalene intermediate is selected from Formula (II-1) or Formula (III-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is selected from the BODIPY-like structural formula (II) or Formula (III) of azapentalene, the coordination center adopts a disubstituted boron coordination center.

[0034] Furthermore, when the structural formula of the benzene precursor adopts Formula (2), the structural formula of the azapentalene intermediate adopts Formula (I-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene adopts the metal complex formula (I) of azapentalene, the preparation method of the structural formula of the large conjugated heteroaryl complex containing azapentalene includes the following steps:

[0035] Mix the azapentalene precursor, benzene precursor, inorganic base, and palladium catalyst, add the first organic solvent, the second organic solvent, and the inorganic solvent under a protective gas atmosphere, perform a coupling reaction, after the reaction ends, extract, dry the organic phase, evaporate the solvent under reduced pressure, and purify the crude product.

[0036] Mix the azapentalene intermediate obtained from the coupling reaction, the inorganic base, and the second organic solvent, dissolve the metal coordination center in the inorganic solvent, and add the inorganic solvent solution of the metal coordination center to the mixture containing the azapentalene intermediate under a protective gas atmosphere for a coordination reaction. After the reaction ends, extract, dry the organic phase, evaporate the solvent under reduced pressure, and purify the crude product to obtain a large conjugated heteroaryl complex containing azapentalene.

[0037] Further, the inorganic base is selected from one or more of potassium carbonate (K2CO3), sodium carbonate (Na2CO3), potassium hydroxide (KOH), and sodium hydroxide (NaOH); the palladium catalyst is selected from one or more of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4), palladium acetate (Pd(OAc)2), and palladium dichloride (PdCl2); the first organic solvent is selected from one or more of toluene, dichloromethane (DCM), tetrahydrofuran (THF), chlorobenzene, and N,N-dimethylformamide (DMF); the second organic solvent is selected from one or more of ethanol and methanol; the inorganic solvent is water; and the molar / volume ratio of the azepine precursor, benzene precursor, inorganic base, palladium catalyst, first organic solvent, second organic solvent, and inorganic solvent required for the coupling reaction is 1 mol:(0.8 - 1.4 mol):(1.5 - 2.5 mol):(0.01 - 0.1 mol):(2 - 6 L):(0.5 - 2 L):(0.5 - 2 L).

[0038] The temperature of the coupling reaction is 60 - 120 °C, and the time is 10 - 16 h.

[0039] The metal coordination center is selected from one or more of beryllium sulfate (BeSO4), zinc acetate (Zn(OAc)2), copper sulfate (CuSO4), and iridium trichloride (IrCl3); and the molar / volume ratio of the azepine intermediate, inorganic base, second organic solvent, metal coordination center, and inorganic solvent required for the coordination reaction is 1 mol:(0.6 - 2 mol):(2 - 4 L):(0.4 - 0.7 mol):(0.5 - 1 L).

[0040] The temperature of the coordination reaction is 30 - 60 °C, and the time is 20 - 32 h.

[0041] As a preferred technical solution, the protective gas is selected from one or more of nitrogen, helium, and argon.

[0042] As a preferred technical solution, the solvent for extraction is selected from one or more of ethyl acetate (Ea) and dichloromethane.

[0043] As a preferred technical solution, the reagent for drying is selected from one or more of anhydrous magnesium sulfate (MgSO4) and anhydrous sodium sulfate (Na2SO4).

[0044] As a preferred technical solution, column chromatography is used for purification.

[0045] As a preferred technical solution, the eluent for column chromatography is petroleum ether (Pe) / ethyl acetate, the volume ratio of the eluent for column chromatography after the coupling reaction is (2-4):1, and the volume ratio of the eluent for column chromatography after the coordination reaction is (4-6):1.

[0046] Further, when the structural formula of the benzene precursor is selected from Formula (3) or Formula (4), the structural formula of the azapentalene intermediate is selected from Formula (Ⅱ-1) or Formula (Ⅲ-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is selected from the BODIPY-like structural formula (Ⅱ) or Formula (Ⅲ) containing azapentalene, the preparation method of the structural formula of the large conjugated heteroaryl complex containing azapentalene includes the following steps:

[0047] Mix a metal hydride, a first organic solvent and a benzene precursor, dissolve the azapentalene precursor in the first organic solvent, add the first organic solvent solution of the azapentalene precursor to the mixture containing the benzene precursor, carry out a coupling reaction, cool to room temperature, neutralize, extract, evaporate the solvent, rinse and filter, and purify the filter cake.

[0048] Under an inert gas atmosphere, mix the azapentalene intermediate obtained from the coupling reaction with the first organic solvent, add an organic base and a disubstituted boron coordination center, carry out a coordination reaction, quench the reaction, extract, wash the organic phase, dry, concentrate the solvent, and purify the residue to obtain a large conjugated heteroaryl complex containing azapentalene.

[0049] Further, when the structural formula of the benzene precursor is Formula (3), the structural formula of the azapentalene intermediate is Formula (Ⅱ-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is the BODIPY-like structural formula (Ⅱ) containing azapentalene on one side, the molar ratio of the benzene precursor to the azapentalene precursor is (0.8-1.4):1.

[0050] Further, when the structural formula of the benzene precursor is Formula (4), the structural formula of the azapentalene intermediate is Formula (Ⅲ-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is the BODIPY-like structural formula (Ⅲ) containing azapentalene on both sides, the molar ratio of the benzene precursor to the azapentalene precursor is (0.8-1.4):2.

[0051] Further, the metal hydride is selected from one or more of sodium hydride (NaH), potassium hydride (KH), and lithium hydride (LiH), the first organic solvent is selected from one or more of toluene, dichloromethane, tetrahydrofuran, chlorobenzene, and N,N-dimethylformamide, the molar / volume ratio of the metal hydride, the benzene precursor, and the required first organic solvent is (2 - 6 mol):(0.8 - 1.4 mol):(30 - 70 L), and the molar / volume ratio of the azepine precursor and the required first organic solvent is 1 mol:(2 - 4 L).

[0052] The temperature of the coupling reaction is 40 - 90 °C, and the time is 10 - 16 h.

[0053] The organic base is selected from one or more of triethylamine and N,N-diisopropylethylamine (DIPEA), the disubstituted boron coordination center uses boron trifluoride diethyl ether complex, and the molar / volume ratio of the azepine intermediate, the required first organic solvent, the organic base, and the disubstituted boron coordination center is 1 mol:(10 - 50 L):(3 - 4.2 mol):(2 - 6 mol).

[0054] The temperature of the coordination reaction is 40 - 100 °C, and the time is 10 - 16 h.

[0055] As a preferred technical solution, the neutralizing reagent is hydrochloric acid, and the concentration of the reagent is 0.5 - 1.5 mol / L.

[0056] As a preferred technical solution, the solvent for extraction after the coupling reaction is selected from one or more of ethyl acetate and dichloromethane.

[0057] As a preferred technical solution, the reagent for rinsing and filtering is petroleum ether / ethyl acetate, and the volume ratio of the reagent is (8 - 12):1.

[0058] As a preferred technical solution, recrystallization is used for purification.

[0059] As a preferred technical solution, the protective gas is selected from one or more of nitrogen, argon, and helium.

[0060] As a preferred technical solution, the quenching reagent is water.

[0061] As a preferred technical solution, the solvent for extraction after the coordination reaction is selected from one or more of ethyl acetate and dichloromethane.

[0062] As a preferred technical solution, the washing reagent is water.

[0063] As a preferred technical solution, the drying reagent is selected from one or more of anhydrous magnesium sulfate and anhydrous sodium sulfate.

[0064] As a preferred technical solution, column chromatography is used for the purification.

[0065] As a preferred technical solution, the eluent for the column chromatography is petroleum ether / ethyl acetate, and the volume ratio of the eluent is (8 - 12):1.

[0066] One of the technical solutions of the present invention is to provide an application of the nitrogen - containing azulene - based large - conjugated heteroaryl complex in organic light - emitting materials.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] (1) The present invention is based on the improvement of the azulene structure. A nitrogen unit is introduced into azulene, and a series of large - conjugated heteroaryl complexes are synthesized based on 1 - azanaphthalene. They have the characteristics of stable chemical properties, strong thermal stability, large molar extinction coefficient, large Stokes shift, and significant red - shift of absorption and emission peaks. Among these three types of luminescent materials, the metal complexes containing nitrogen - containing azulene have a relatively high lifetime, a large Stokes shift, and a relatively high thermal decomposition temperature. The BODIPY - like structure with nitrogen - containing azulene on one side has a relatively high photoluminescence quantum efficiency. The BODIPY - like structure with nitrogen - containing azulene on both sides has a large molar extinction coefficient, absorption peaks, and emission peaks at longer wavelengths. And compared with the conjugated derivatives of traditional polycyclic aromatic - structured azulene, these conjugated derivatives of nitrogen - containing azulene exhibit bright fluorescence characteristics to varying degrees;

[0069] (2) The present invention has not only made innovative progress in the research of luminescent materials with azulenyl structures. In view of the unique molecular properties of azulenyl, appropriate structural modification of azulenyl can enhance the performance of azulenyl - based fluorescent molecules, opening up new ways and developing new alternative materials for applications such as organic light - emitting diodes (OLEDs), luminescent materials, fluorescent probes, fluorescent tracers, fluorescent sensors, and biological imaging;

[0070] (3) The preparation method of the present invention has mild conditions, short reaction time, high yield, and simple product separation and purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 1H NMR spectrum of the azulenyl - based intermediate in Example 1 of the present invention 1 1H NMR

[0072] Figure 2 1H NMR spectrum of the nitrogen - containing azulene - based large - conjugated heteroaryl complex in Example 1 of the present invention

[0073] Figure 3 1H NMR spectrum of the azulenyl - based intermediate in Example 2 of the present invention

[0074] Figure 4 1H NMR spectrum of the large conjugated heteroaryl complex of nitrogen-containing azulene in Example 2 of the present invention;

[0075] Figure 5 UV absorption and fluorescence emission spectra of the large conjugated heteroaryl complex of nitrogen-containing azulene in Example 2 of the present invention;

[0076] Figure 6 Thermogravimetric analysis diagram of the large conjugated heteroaryl complex of nitrogen-containing azulene in Example 1 of the present invention. Detailed implementation manners

[0077] The present invention will be described in detail below in conjunction with specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0078] Unless otherwise specified, the equipment used in the following embodiments are all conventional equipment in the art; unless otherwise specified, the reagents used are all commercially available products or prepared by conventional methods in the art. Those not described in detail in the following embodiments can all be achieved by conventional experimental means in the art.

[0079] The metal complexes of nitrogen-containing azulene and their preparation methods will be described below.

[0080] Example 1.1:

[0081] A large conjugated heteroaryl complex of nitrogen-containing azulene and its preparation method, the reaction equation is as follows:

[0082]

[0083] The specific steps are as follows:

[0084] S1.1. Preparation of compound A-1

[0085] Add 2-chloro-1-azulene (Compound 1-1, 0.82 g, 5 mmol), 2-hydroxybenzeneboronic acid (0.83 g, 6 mmol), potassium carbonate (K2CO3, 1.38 g, 10 mmol) and tetrakis(triphenylphosphine)palladium (Pd(PPh3)4, 0.28 g, 0.25 mmol) into a 50 mL reaction tube. After purging three times under a nitrogen atmosphere, successively add 20 mL of toluene, 5 mL of ethanol and 5 mL of water under nitrogen protection. Then heat the mixture to 110 °C and stir overnight for 12 h. After the reaction is completed, extract three times with ethyl acetate (Ea), combine the organic phases, and dry with anhydrous sodium sulfate (Na2SO4). After evaporating the solvent under reduced pressure, purify the crude product by column chromatography with petroleum ether (Pe):ethyl acetate = 3:1 to obtain intermediate compound A-1 (0.91 g) with a yield of 82%. The 1H NMR spectrum is shown in Figure 1 ;

[0086] S1.2. Preparation of Compound A

[0087] Add 8 mL of methanol to Compound A-1 (663.6 mg, 3 mmol) and sodium hydroxide (NaOH, 156 mg, 3.9 mmol) in a 25 mL reaction tube. At the same time, dissolve beryllium sulfate tetrahydrate (BeSO4·4H2O, 248 mg, 1.4 mmol) in 2 mL of water in another 10 mL reaction tube. After purging three times under a nitrogen atmosphere, dropwise add the aqueous solution of beryllium sulfate tetrahydrate under nitrogen protection. Then heat the mixture to 40 °C and stir for 24 h. After the reaction is completed, extract three times with ethyl acetate, combine the organic phases, and dry with anhydrous sodium sulfate. After evaporating the solvent under reduced pressure, purify the crude product by column chromatography with petroleum ether:ethyl acetate = 5:1 to obtain product Compound A (1.12 g) with a yield of 84%. The 1H NMR spectrum is shown in Figure 2 。

[0088] The following describes a class of BODIPY compounds containing nitrogen heterocyclic azulene on one side and their preparation methods.

[0089] Example 2:

[0090] A nitrogen heterocyclic azulene-containing large conjugated heteroaryl complex and its preparation method. The reaction equation is as follows:

[0091]

[0092] The specific steps are as follows:

[0093] S2.1. Preparation of Compound B-1

[0094] In a 100 mL reaction tube, 60% sodium hydride (NaH, 160.0 mg, 4 mmol) was added to 50 mL of tetrahydrofuran (THF), and benzothiazole-2-acetonitrile (209.4 mg, 1.2 mmol) was added. The mixture was stirred at room temperature for 1 h. Meanwhile, in another 100 mL reaction tube, 2-bromo-1-azepine (Compound 1-2, 208.0 mg, 1 mmol) was added to 3 mL of tetrahydrofuran to completely dissolve it. The tetrahydrofuran solution of 2-bromo-1-azepine was added, and then the mixture was heated to 70 °C and refluxed overnight for 12 h. After cooling to room temperature, 0.1 mol / L hydrochloric acid was added for neutralization, and extraction was carried out using dichloromethane (DCM). Due to solubility problems, column chromatography could not be performed. Therefore, the mixture was filtered by rinsing with petroleum ether:ethyl acetate = 10:1, and the collected filter cake was recrystallized and purified to obtain intermediate Compound B-1 (230.4 mg) with a yield of 76%. The 1H NMR spectrum is shown in Figure 3 ;

[0095] S2.2. Preparation of Compound B

[0096] After purging a 50 mL reaction tube three times under a nitrogen atmosphere, under nitrogen protection, 30 mL of anhydrous toluene was added to Compound B-1 (301.4 mg, 1 mmol). The mixture was stirred at room temperature for 10 min, triethylamine (0.5 mL, 3.6 mmol) and boron trifluoride diethyl ether complex (0.5 mL, 4 mmol) were added, and then the mixture was heated to 80 °C and stirred overnight for 12 h. The reaction mixture was quenched with water, extracted with ethyl acetate, the organic layer was washed with water, and dried over anhydrous magnesium sulfate (MgSO4). After concentration of the solvent, the residue was purified by column chromatography with petroleum ether:ethyl acetate = 10:1 to obtain product Compound B (168.6 mg) with a yield of 48%. The 1H NMR spectrum is shown in Figure 4 .

[0097] The following describes a BODIPY-like compound containing nitrogen azepine on both sides and its preparation method.

[0098] Example 3:

[0099] A large conjugated heteroaryl complex containing nitrogen azepine and its preparation method. The reaction equation is as follows:

[0100]

[0101] The specific steps are as follows:

[0102] S3.1. Preparation of Compound C-1

[0103] In a 100 mL reaction tube, 60% sodium hydride (160.0 mg, 4 mmol) was added to 50 mL of tetrahydrofuran, and 2,6-dicyano-benzo[1,2-d:4,5-d']bisthiazole (270.3 mg, 1 mmol) was added. The mixture was stirred at room temperature for 1 h. Meanwhile, in another 100 mL reaction tube, 2-bromo-1-azulene (Compound 1-2, 458.9 mg, 2.2 mmol) was added to 6.6 mL of tetrahydrofuran to completely dissolve it. The tetrahydrofuran solution of 2-bromo-1-azulene was added, and then the mixture was heated to 60 °C and refluxed overnight for 12 h. After cooling to room temperature, 0.1 mol / L hydrochloric acid was added for neutralization, and extraction was carried out with dichloromethane. Due to solubility problems, column chromatography could not be carried out, so the mixture was washed with petroleum ether:ethyl acetate = 10:1 and filtered. The filter cake was collected and purified by recrystallization to obtain Compound C-1 (412.8 mg) with a yield of 79%;

[0104] S3.2 Preparation of Compound C

[0105] After purging a 50 mL reaction tube three times under a nitrogen atmosphere, under nitrogen protection, 30 mL of anhydrous toluene was added to Compound C-1 (524.6 mg, 1 mmol). The mixture was stirred at room temperature for 10 min, triethylamine (0.5 mL, 3.6 mmol) and boron trifluoride diethyl ether complex (0.5 mL, 4 mmol) were added, and then the mixture was heated to 80 °C and stirred overnight for 12 h. The reaction mixture was quenched with water, extracted with ethyl acetate, the organic layer was washed with water, and dried over anhydrous magnesium sulfate. After concentration of the solvent, the residue was purified by column chromatography with petroleum ether:ethyl acetate = 10:1 to obtain Compound C (314.4 mg) with a yield of 51%.

[0106] The above complexes were subjected to the following detections or tests, and then the detection or test results were analyzed.

[0107] Test Example

[0108] The fluorescence properties and thermal stability of the above complexes were tested.

[0109] The fluorescence property data of the complexes in Examples 1 to 3 are shown in Table 1.

[0110] Table 1 Fluorescence Property Data of the Complexes in Examples 1 to 3

[0111] Complex <![CDATA[λ abs [nm]]]> <![CDATA[λ em [nm]]]> <![CDATA[ε abs [M -1 cm -1 > <![CDATA[Φ PL [%]]]> τ [ns] <![CDATA[Stokes shift [cm -1 > A 508 596 7400 0.6 5.86 2906 B 530 607 23500 2.5 0.95 2395 C 552 642 26800 1.9 1.21 2540

[0112] As shown in Table 1 and Figure 5 and Figure 6As shown, the absorption and emission peaks of the complexes in Examples 1 to 3 are all in the visible light region. Due to the introduction of azapentalene and the synthesis of a large conjugated system in these three types of luminescent materials, all three have red-shifted absorption and emission peaks, a large Stokes shift, and a high photoluminescence quantum efficiency Φ PL showing different degrees of bright luminescence; among them, in Example 1, due to the tight metal coordination complex in Complex A and the increase in the overall conjugation degree of the material, Complex A exhibits good thermal stability (higher lifetime τ, larger Stokes shift, and higher thermal decomposition temperature of 445 °C); in contrast, in Examples 2 and 3, due to the introduction of the electron-withdrawing group cyano in Complexes B and C, the overall absorption and emission peaks are further red-shifted, and due to the effective coordination of the boron trifluoride complex, they have a high photoluminescence quantum efficiency Φ PL , Complex C exhibits a larger molar extinction coefficient ε due to a larger conjugation degree and better symmetry compared to Complex B abs and an absorption peak λ at a longer wavelength abs and an emission peak λ em .

[0113] Comparative example:

[0114] The structure of Inv-2 in Patent US6885026B1 is a complex formed by coupling 2-bromo-quinoline and benzothiazole acetonitrile followed by coordination complexation with boron trifluoride diethyl ether. The patent states that the emission peak of the Inv-2 structure is at 470 nm, while the emission peak of the complex in Example 2, which is an isomer of the Inv-2 structure, is red-shifted to 607 nm. The absorption and emission peaks of the conjugated derivatives of azapentalene in the present invention have an obvious red shift relative to the quinoline derivatives, laying a fundamental work for the subsequent research on red and near-infrared fluorescent materials.

[0115] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. Persons familiar with the art can obviously make various modifications to these embodiments easily and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention as disclosed should be within the protection scope of the present invention.

Claims

1. A large conjugated heteroaryl complex containing a nitrogen heterazulene, characterized in that, The structural formula of the complex is selected from Formula (I), Formula (II) or Formula (III), wherein, M is selected from a beryllium atom, a zinc atom, a copper atom or an iridium atom, R1 is selected from a hydrogen atom, a deuterium atom, a methyl group, a methoxy group or a tert-butyl group, and R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a hydroxyl group, a cyano group, a methyl group, a methoxy group, a tert-butyl group or a halogen atom.

2. A method for preparing a large-conjugated heteroaryl complex containing a nitrogen heteroazulene as described in claim 1, characterized in that, The method comprises the following steps: Mixing an azacarbazole precursor and a benzene precursor, performing a coupling reaction, mixing the azacarbazole intermediate obtained from the coupling reaction and a coordination center, and performing a coordination reaction to obtain a large conjugated heteroaryl complex containing azacarbazole.

3. The preparation method of a large-conjugated heteroaryl complex containing nitrogen heterazulene according to claim 2, characterized in that, The structural formula of the azacarbazole precursor is Formula (1), wherein, R1 is selected from a hydrogen atom, a deuterium atom, a methyl group, a methoxy group or a tert-butyl group, and X is a halogen atom; The structural formula of the benzene precursor is selected from Formula (2), Formula (3) or Formula (4), wherein, R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a hydroxyl group, a cyano group, a methyl group, a methoxy group, a tert-butyl group or a halogen atom, and R5 is selected from a boronic acid group or a borate group; The structural formula of the azacarbazole intermediate is selected from Formula (I-1), Formula (II-1) or Formula (III-1), wherein, R1 is selected from a hydrogen atom, a deuterium atom, a methyl group, a methoxy group or a tert-butyl group, and R2, R3 and R4 are independently selected from a hydrogen atom, a deuterium atom, a nitro group, a hydroxyl group, a cyano group, a methyl group, a methoxy group, a tert-butyl group or a halogen atom; The coordination center is selected from a metal coordination center or a disubstituted boron coordination center.

4. The preparation method of a large-conjugated heteroaryl complex containing nitrogen heteroaubepine according to claim 3, characterized in that, When the structural formula of the benzene precursor is Formula (2), the structural formula of the azacarbazole intermediate is Formula (I-1), and the structural formula of the large conjugated heteroaryl complex containing azacarbazole is the metal complex formula (I) containing azacarbazole, the preparation method of the structural formula of the large conjugated heteroaryl complex containing azacarbazole comprises the following steps: Mixing an azacarbazole precursor, a benzene precursor, an inorganic base and a palladium catalyst, adding a first organic solvent, a second organic solvent and an inorganic solvent, performing a coupling reaction, mixing the azacarbazole intermediate obtained from the coupling reaction, the inorganic base and the second organic solvent, dissolving the metal coordination center in the inorganic solvent, adding the inorganic solvent solution of the metal coordination center to the mixture containing the azacarbazole intermediate, and performing a coordination reaction to obtain a large conjugated heteroaryl complex containing azacarbazole.

5. The preparation method of a large conjugated heteroaryl complex containing nitrogen heterazulene according to claim 4, characterized in that, The inorganic base is selected from one or more of potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, the palladium catalyst is selected from one or more of tetrakis(triphenylphosphine)palladium, palladium acetate, palladium dichloride, the first organic solvent is selected from one or more of toluene, dichloromethane, tetrahydrofuran, chlorobenzene, N,N-dimethylformamide, the second organic solvent is selected from one or more of ethanol, methanol, the inorganic solvent is water, and the molar / volume ratio of the azacarbazole precursor, the benzene precursor, the inorganic base, the palladium catalyst, the first organic solvent, the second organic solvent and the inorganic solvent required for the coupling reaction is 1mol:(0.8 - 1.4mol):(1.5 - 2.5mol):(0.01 - 0.1mol):(2 - 6L):(0.5 - 2L):(0.5 - 2L), The temperature of the coupling reaction is 60 to 120 °C, and the time is 10 to 16 h. The metal coordination center is selected from one or more of beryllium sulfate, zinc acetate, copper sulfate, and iridium trichloride. The molar / volume ratio of the azapentalene intermediate, inorganic base, second organic solvent, metal coordination center to the inorganic solvent required for the coordination reaction is 1 mol:(0.6 - 2 mol):(2 - 4 L):(0.4 - 0.7 mol):(0.5 - 1 L). The temperature of the coordination reaction is 30 to 60 °C, and the time is 20 to 32 h.

6. The preparation method of a large conjugated heteroaryl complex containing nitrogen heteroazulene according to claim 3, characterized in that, When the structural formula of the benzene precursor is selected from Formula (3) or Formula (4), the structural formula of the azapentalene intermediate is selected from Formula (Ⅱ-1) or Formula (Ⅲ-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is selected from the azapentalene-containing BODIPY-like structural formula (Ⅱ) or Formula (Ⅲ), the preparation method of the structural formula of the large conjugated heteroaryl complex containing azapentalene includes the following steps: Mix a metal hydride, a first organic solvent, and a benzene precursor. Dissolve the azapentalene precursor in the first organic solvent. Add the first organic solvent solution of the azapentalene precursor to the mixture containing the benzene precursor, and perform a coupling reaction. Mix the azapentalene intermediate obtained from the coupling reaction and the first organic solvent, add an organic base and a disubstituted boron coordination center, and perform a coordination reaction to obtain a large conjugated heteroaryl complex containing azapentalene.

7. The preparation method of a large-conjugated heteroaryl complex containing nitrogen heteroazulene according to claim 6, characterized in that, When the structural formula of the benzene precursor is Formula (3), the structural formula of the azapentalene intermediate is Formula (Ⅱ-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is the BODIPY-like structural formula (Ⅱ) with azapentalene on one side, the molar ratio of the benzene precursor to the azapentalene precursor is (0.8 - 1.4):

1.

8. The preparation method of a large conjugated heteroaryl complex containing nitrogen heteroazulene according to claim 6, characterized in that, When the structural formula of the benzene precursor is Formula (4), the structural formula of the azapentalene intermediate is Formula (Ⅲ-1), and the structural formula of the large conjugated heteroaryl complex containing azapentalene is the BODIPY-like structural formula (Ⅲ) with azapentalene on both sides, the molar ratio of the benzene precursor to the azapentalene precursor is (0.8 - 1.4):

2.

9. The preparation method of a large-conjugated heteroaryl complex containing nitrogen heterocyclic azulene according to claim 6, characterized in that, The metal hydride is selected from one or more of sodium hydride, potassium hydride, and lithium hydride. The first organic solvent is selected from one or more of toluene, dichloromethane, tetrahydrofuran, chlorobenzene, and N,N-dimethylformamide. The molar / volume ratio of the metal hydride, benzene precursor to the first organic solvent required for them is (2 - 6 mol):(0.8 - 1.4 mol):(30 - 70 L). The molar / volume ratio of the azapentalene precursor to the first organic solvent required for it is 1 mol:(2 - 4 L). The temperature of the coupling reaction is 40 to 90 °C, and the time is 10 to 16 h. The organic base is selected from one or more of triethylamine and N,N-diisopropylethylamine, the disubstituted boron coordination center adopts boron trifluoride diethyl ether complex, and the molar / volume ratio of the azulene intermediate to the first organic solvent, organic base, and disubstituted boron coordination center required by it is 1 mol:(10-50 L):(3-4.2 mol):(2-6 mol). The temperature of the coordination reaction is 40-100 °C, and the time is 10-16 h.

10. Application of a large conjugated heteroaryl complex containing azulene as described in claim 1 in an organic light-emitting material.

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