Quinoxalinyl organic boron dye as well as preparation method and application thereof

Abstract

The invention discloses a quinoxaline-based organic boron dye as well as a preparation method and application thereof. The structural formula of the quinoxaline-based organic boron dye has two spatial isomers, namely a cis (synn-) spatial isomer and a trans (anti-) spatial isomer; the dye is obtained by coordinating a novel N, O-type chelating skeleton constructed based on 2, 3-dihydrazinoquinoxaline and an aromatic aldehyde compound with a boric acid derivative, a one-pot two-step method is adopted, and the dye has the advantages of being simple and convenient in synthesis route, free of complex purification, high in substrate applicability, easy to produce on a large scale and the like. The quinoxalinyl organic boron dye shows excellent photophysical properties, the Stokes shift generally exceeds 100 nm, and fluorescence self-absorption interference is effectively reduced; meanwhile, the fluorescent probe has high molar absorption coefficient, high fluorescence quantum yield and excellent light stability, and has potential application value in the fields of biological imaging, optical sensing, light diagnosis and treatment and the like.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to a quinoxaline-based organoboron dye, its preparation method, and its application. Background Technology

[0002] Organic fluorescent dyes play an irreplaceable role in optical detection, bioimaging, and photomedicine due to their excellent photophysical properties and structural tunability. Among them, BODIPY (fluorinated boron dipyrrole) dyes have attracted widespread attention due to their high molar absorptivity, high fluorescence quantum yield, and excellent photochemical stability (Chem. Soc. Rev., 2014, 43, 4778; Coord. Chem. Rev., 2025, 545, 217030). However, these dyes still face two major bottlenecks in practical applications: (1) severe self-absorption effect: BODIPY dyes generally have a small Stokes shift (usually less than 30 nm), which easily leads to the overlap of emission and absorption spectra, resulting in severe self-absorption; (2) aggregation-induced quenching (ACQ): the traditional planar rigid structure makes them prone to fluorescence quenching in condensed matter systems or high-concentration environments, which significantly limits their application in solid-state luminescent materials and biodetection. Therefore, overcoming this bottleneck through molecular design has become an important research direction in this field in recent years. Existing technologies already include some fluorescent dyes that utilize quinoxalin groups as the core framework, such as the quinoxalin-based difluoroboron fluorescent compound disclosed in CN202410484855.X. Its core structure is a difluoroboron (BF2) compound based on the coordination of quinoxalin nitrogen and oxygen atoms, with two fluorine atoms attached to the boron atom. The molecular spatial configuration tends towards a planar rigid structure. This planar structure is highly susceptible to aggregation-induced quenching (ACQ), limiting its application in solid-state or high-concentration biological environments.

[0003] In recent years, constructing N,O-type chelate ligands and introducing aromatic groups along the boron atom axis has become an effective strategy for suppressing dye aggregation quenching (Coord. Chem. Rev., 2024, 513, 215892). However, such methods typically rely on structurally complex ligand systems, involve cumbersome synthetic steps, and often result in compounds existing in a single configuration, making it difficult to achieve controllable construction and separation of different spatial isomers. Furthermore, the impact of cis / trans configuration differences on photophysical properties lacks systematic research. In addition, existing modification strategies have limited effectiveness in enhancing the Stokes shift, making it difficult to simultaneously achieve a large Stokes shift and excellent solid-state luminescence performance.

[0004] Therefore, developing a novel organic boron fluorescent dye system with a novel structure, a simple synthesis route, and the ability to precisely regulate photophysical properties through spatial configuration control remains a pressing technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a quinoxaline-based organoboron dye, its preparation method, and its applications. The aim is to solve the problems of small Stokes shift and aggregation-induced quenching in existing organoboron dyes by constructing a novel N,O-type polydentate ligand framework based on 2,3-dihydrazinoquinoxaline and utilizing its unique spatial geometric properties.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a quinoxalin-based organoboron dye, BOSQUIs, with the following structural formula:

[0008]

[0009] Among them, Ar 1 Ar 2 Each is independently selected from substituted or unsubstituted C6-C. 30 Aromatic groups or C3-C 30 heteroaryl groups.

[0010] As shown in the following formula, the dye has two spatial isomer configurations: cis (syn-) and trans (anti-). Ar on both sides 2 When the spatial orientations are the same, the compound is a cis isomer; Ar on both sides 2 When the spatial orientations are different, the compound is a trans isomer. 2 The spatial orientation of a compound determines its cis-trans isomerism.

[0011]

[0012] As a preferred option, Ar 1 Each is independently selected from, but not limited to, a benzene ring, a benzothiophene ring, a benzofuran ring, a naphthalene ring, a juulonidin ring, a quinoline ring, a pyrene ring, or a derivative thereof; Ar 2 Each is independently selected from, but not limited to, one of phenyl, thiophene, furanyl, pyridyl, biphenyl, naphthyl, pyrene, or their derivatives.

[0013] Preferably, the substitution is silicon-based.

[0014] Secondly, the present invention provides a method for preparing the above-mentioned organoboron dye, comprising the following steps:

[0015] Step (1): Add 2,3-dihydrazinoquinoxaline to the first solvent, dissolve it, add aromatic aldehyde or its derivative, add acid to react, and obtain intermediate N,O type ligand I;

[0016]

[0017] Step (2): Dissolve intermediate N,O type ligand I in a second solvent, add alkali and organoboronic acid compound to react and obtain the above-mentioned quinoxalin-based organoboronic dye BOSQUIs;

[0018]

[0019] Preferably, the molar ratio of 2,3-dihydrazinoquinoxaline to aromatic aldehyde or its derivative is 1:(2.0~3.0); and the molar ratio of intermediate N,O type ligand I to organoboronic acid compound is 1:(2.0~5.0).

[0020] Preferably, the first solvent and the second solvent are each independently selected from one or more of methanol, ethanol, isopropanol, dichloromethane, chloroform, 1,2-dichloroethane, toluene, xylene, chlorobenzene, tetrahydrofuran, 1,4-dioxane, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide.

[0021] Preferably, the acid comprises an organic acid or an inorganic acid; the organic acid is selected from one or more of acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, or trifluoromethanesulfonic acid; the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid. The base comprises an organic base or an inorganic base; the organic base is selected from one or more of triethylamine, N,N-diisopropylethylamine, pyridine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), or 1,5-diazabicyclo[4.3.0]non-5-ene; the inorganic base is selected from one or more of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, sodium hydroxide, or potassium hydroxide.

[0022] Preferably, the reaction temperature in step (1) is 80°C and the reaction time is 8~10 h; the reaction temperature in step (2) is 110°C and the reaction time is 6~8 h.

[0023] Preferably, the preparation method further includes a purification and separation process, specifically column chromatography and recrystallization, wherein the developing solvent for column chromatography is selected from a mixed solvent of dichloromethane and petroleum ether in a volume ratio of 1:(1~9).

[0024] Thirdly, the present invention provides the application of the above-mentioned quinoxalin-based organoboron dyes BOSQUIs in bioimaging, fluorescence sensing, photodynamic therapy, or photothermal therapy.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention successfully constructed a novel N,O-type ligand platform through the condensation reaction of 2,3-dihydrazinoquinoxaline with salicylaldehyde compounds. Further coordination with boric acid derivatives introduced aromatic groups along the boron atom axis, forming a three-dimensional structure composed of a "ligand plane" and "axial aryl groups." Utilizing the steric hindrance of substituents and the difference in benzene ring orientation, the precise construction and separation of cis (syn-) and anti- isomers were achieved. Studies show that due to the steric hindrance generated by the axial aryl groups and the restricted intramolecular motion mechanism, this series of compounds exhibits excellent photostability and high molar absorbance. Furthermore, the two isomers show significant structure-activity differences in solid-state luminescence performance: the anti-isomer exhibits a significant aggregation-induced emission (AIE) effect and viscosity response, with a significantly enhanced fluorescence signal intensity. Both types achieve Stokes shifts exceeding 100 nm, effectively reducing self-absorption interference. Thanks to its simple synthetic process and easily modifiable structure, this novel organoboron dye shows promising application prospects in imaging complex biological environments.

[0027] This invention employs a one-pot, two-step method, where intermediate ligands can be obtained with high-purity products through in-situ precipitation, greatly improving production efficiency and industrial feasibility. Attached Figure Description

[0028] The accompanying drawings are used to further explain specific embodiments of the present invention and do not constitute a limitation thereof. In the drawings:

[0029] Figure 1 This is a single-crystal structure diagram of product A-4a obtained in the embodiments of the present invention, wherein (a) is the chemical structural formula, (b) is a side view of a single molecule, (c) is the packing analysis of the dimer, and (d) is a one-dimensional packing diagram of the crystal.

[0030] Figure 2 This is a single-crystal structure diagram of product B-4a obtained in the embodiments of the present invention, wherein (a) is the chemical structural formula, (b) is a side view of a single molecule, (c) is the packing analysis of the dimer, and (d) is a one-dimensional packing diagram of the crystal.

[0031] Figure 3 These are the normalized absorption and emission spectra of several representative organoboron dyes prepared in dichloromethane solution in the embodiments of the present invention.

[0032] Figure 4 These are the emission spectra of products A-4a and B-4a obtained in the embodiments of the present invention in H2O / THF mixed systems with different ratios, used to demonstrate their aggregation-induced emission (AIE) properties.

[0033] Figure 5 These are the emission spectra of products A-4a and B-4a obtained in the embodiments of the present invention in different proportions of Glycerol / MeOH mixed systems, used to demonstrate their viscosity response properties. Detailed Implementation

[0034] The present invention will be further described in detail below through specific embodiments.

[0035] As mentioned above, the present invention provides a quinoxalin-based organoboron dye, BOSQUIs, having two spatial isomer configurations, cis (syn-) or trans (anti-), as shown below:

[0036]

[0037] Among them, Ar 1 Ar 2 Each is independently selected from substituted or unsubstituted C6-C. 30 Aromatic groups or C3-C 30 heteroaryl groups; further, Ar 1 Each is independently selected from, but not limited to, a benzene ring, a benzothiophene ring, a benzofuran ring, a naphthalene ring, a juulonidin ring, a quinoline ring, a pyrene ring, or a derivative thereof; Ar 2 Each is independently selected from, but not limited to, one of phenyl, thiophene, furanyl, pyridyl, biphenyl, naphthyl, pyrene, or their derivatives; the substitution is optionally of various types, such as silyl substitution.

[0038] This invention also provides a method for preparing the above-mentioned quinoxalin-based organoboron dyes BOSQUIs, comprising:

[0039] (1) 2,3-Dihydrazinoquinoxaline was added to the first solvent. After it was completely dissolved, aromatic aldehyde or its derivative was added. The mixture was refluxed and stirred until most of the raw materials were dissolved. Then, acid was added and the first contact reaction was carried out at 80°C. After the reaction was carried out for 8-10 h, the precipitate obtained from the reaction was filtered and washed to obtain intermediate N,O type ligand I. The molar ratio of 2,3-dihydrazinoquinoxaline to aromatic aldehyde or its derivative was 1: (2.0-3.0).

[0040]

[0041] (2) Dissolve the ligand described in step (1) in a second solvent. After the ligand is completely dissolved, add the base and organoboronic acid compound in sequence. Carry out the second contact reaction at 110°C. After reacting for 6-8 h, the product is purified and separated by column chromatography and recrystallization to obtain the cis isomer shown in general formula (A) and the trans isomer shown in general formula (B). The molar ratio of intermediate N,O type ligand I to organoboronic acid compound is 1: (2.0-5.0).

[0042]

[0043] In one embodiment of the present invention, the first solvent and the second solvent are each independently selected from one or more of methanol, ethanol, isopropanol, dichloromethane, chloroform, 1,2-dichloroethane, toluene, xylene, chlorobenzene, tetrahydrofuran, 1,4-dioxane, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide. Those skilled in the art can select according to actual needs, and no limitation is made here.

[0044] In one embodiment of the present invention, the acid includes an organic acid or an inorganic acid; the organic acid is selected from one or more of acetic acid, trifluoroacetic acid, p-toluenesulfonic acid or trifluoromethanesulfonic acid; the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid. Those skilled in the art can select according to actual needs, and no limitation is made here.

[0045] In one embodiment of the present invention, the base includes an organic base or an inorganic base; the organic base is selected from one or more of triethylamine, N,N-diisopropylethylamine, pyridine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene; the inorganic base is selected from one or more of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, sodium hydroxide or potassium hydroxide. Those skilled in the art can select according to actual needs, and no limitation is made here.

[0046] The present invention will be further described below.

[0047] Example 1

[0048]

[0049] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-1a (37% yield) and B-1a (33% yield).

[0050] A-1a: 1 H NMR (500 MHz, CDCl3) δ 8.55 (s, 2H), 7.64 (dd, J = 7.0, 1.7Hz, 2H), 7.31 – 7.21 (m, 4H), 7.19 – 7.10 (m, 6H), 7.12 – 7.05 (m, 2H), 7.04– 6.95 (m, 6H), 6.82 (dd, J = 5.5, 3.3 Hz, 2H). 13 C NMR (125 MHz, CDCl3) δ155.13, 151.26, 144.71, 136.91, 133.72, 131.85, 131.80, 130.97, 128.19,127.83, 127.70, 127.62, 124.05, 120.94, 119.66, 118.60, 117.60. HRMS-ESI:calcd [C 34 H 24 B2N6O2+H] + 571.2220; found 571.2247.

[0051] B-1a: 1H NMR (500 MHz, CDCl3) δ 8.52 (s, 2H), 7.61 (dd, J = 7.0, 1.8Hz, 2H), 7.28 – 7.18 (m, 4H), 7.16 – 7.02 (m, 8H), 7.01 – 6.92 (m, 6H), 6.79(dd, J = 5.5, 3.3 Hz, 2H). 13 C NMR (100 MHz, CDCl3) δ 155.15, 151.25, 144.73,144.93,136.81, 133.71, 131.86, 131.81, 130.99, 128.21, 127.85, 127.68,127.61, 124.04, 120.80, 119.65, 118.57, 117.50,117.58,117.60. HRMS-ESI: calcd[C 34 H 24 B2N6O2+H] + 571.2220; found 571.2233.

[0052] Example 2

[0053]

[0054] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C and refluxed. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, pyridine-4-boronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C and refluxed for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-1b (30% yield) and B-1b (29% yield).

[0055] A-1b: 1H NMR (500 MHz, CDCl3) δ 8.40 - 8.35 (m, 2H), 8.05 (s, 1H), 7.58(dd, J = 7.7, 1.4 Hz, 10H), 7.54 (s, 1H), 7.46 - 7.41 (m, 2H), 7.34 - 7.27(m, 1H), 7.27 - 7.18 (m, 2H), 7.11 - 7.02 (m, 2H), 6.78 (s, 1H). 13 C NMR (125MHz, CDCl3) δ 160.50, 160.26, 149.55, 145.95, 144.84, 135.13, 133.44, 132.30,128.53, 128.02, 126.09, 122.82, 122.07, 118.05, 116.61, 114.21, 114.14. HRMS-ESI: calcd [C 32 H 22 B2N8O2+H] + 573.2125; found 573.2157.

[0056] B-1b: 1 H NMR (500 MHz, CDCl3) δ 8.45 - 8.40 (m, 2H), 8.09 (s, 1H), 7.62(dd, J = 7.7, 1.4 Hz, 10H), 7.59 (s, 1H), 7.51 - 7.44 (m, 2H), 7.38 - 7.31(m, 1H), 7.30 - 7.22 (m, 2H), 7.18 - 7.08 (m, 2H), 6.83 (s, 1H). 13 C NMR (125MHz, CDCl3) δ 160.66, 160.26, 149.54, 148.24, 145.98, 144.83, 135.15, 133.44,132.38, 132.30, 128.33, 128.02, 126.07, 122.76, 122.04, 117.01, 116.72,115.62, 115.85. HRMS-ESI: calcd [C 32 H 22 B2N8O2+H] + 573.2125; found 573.2132.

[0057] Example 3

[0058]

[0059] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C and refluxed. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly for the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, 2-thiopheneboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C and refluxed for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-1c (37% yield) and B-1c (33% yield).

[0060] A-1c: 1 H NMR (500 MHz, CDCl3) δ 8.07 (s, 1H), 7.95 (t, J = 7.9 Hz, 2H), 7.58 (m, 10H), 7.36 - 7.27 (m, 2H), 7.27 - 7.22 (m, 1H), 7.25 - 7.18 (m, 2H),7.13 - 7.02 (m, 2H). 13 C NMR (125 MHz, CDCl3) δ 161.44,160.11, 160.02, 144.66,137.78, 133.33, 133.25, 132.30, 129.49, 128.53, 127.93, 127.01, 126.09,122.82, 122.07, 118.09, 116.61, 115.54, 115.51. HRMS-ESI: calcd [C 30 H 20 B2N6O2S2+H] + 583.1348; found 583.1325.

[0061] B-1c: 1H NMR (500 MHz, CDCl3) δ 8.09 (s, 1H), 7.98 (t, J = 7.9 Hz, 2H), 7.58 - 7.62 (m, 10H), 7.38 - 7.25 (m, 2H), 7.29 - 7.24 (m, 1H), 7.28 - 7.20(m, 2H), 7.15 - 7.05(m, 2H). 13 C NMR (126 MHz, CDCl3) δ 161.54,160.01, 159.43,145.66, 137.79, 133.33, 132.35, 132.30, 128.49, 128.47, 127.95, 127.91,127.01, 126.55, 122.82, 122.07, 118.11, 116.61, 115.58. HRMS-ESI: calcd[C 30 H 20 B2N6O2S2+H] + 583.1348; found 583.1342.

[0062] Example 4

[0063]

[0064] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, 2-furanboric acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-1d (39% yield) and B-1d (32% yield).

[0065] A-1d: 1H NMR (500 MHz, CDCl3) δ 8.06 (s, 1H), 7.60 - 7.56 (m, 10H),7.46 (d, J = 1.6 Hz, 1H), 7.34 - 7.27 (m, 1H), 7.26 - 7.18 (m, 2H), 7.11 -7.02 (m, 2H), 6.61 (d, J = 4.9 Hz, 1H), 6.52 (dd, J = 4.9, 1.6 Hz, 1H), 6.27(s, 1H). 13 C NMR (126 MHz, CDCl3) δ 159.47, 159.37, 147.13, 145.08, 137.35,132.80, 132.30, 128.53, 127.62, 126.06, 122.82, 122.07, 118.10, 116.62,112.67. HRMS-ESI: calcd [C 30 H 20 B2N6O4+H] + 551.1805; found 551.1852.

[0066] B-1d: 1 H NMR (500 MHz, CDCl3) δ 8.05 (s, 1H), 7.58 – 7.54 (m, 10H),7.45 (d, J = 1.6 Hz, 1H), 7.32 - 7.28 (m, 1H), 7.25 - 7.16 (m, 2H), 7.10 -7.03 (m, 2H), 6.60 (d, J = 4.9 Hz, 1H), 6.51 (dd, J = 4.9, 1.6 Hz, 1H), 6.25(s, 1H). 13 C NMR (125 MHz, CDCl3) δ 159.42, 159.35, 147.10, 145.06, 138.21,137.34, 132.30, 132.28, 128.55, 127.60, 126.01, 122.78, 122.04, 118.06,116.61, 112.65, 111.34. HRMS-ESI: calcd [C 30 H 20 B2N6O4+H] + 551.1805; found551.1818.

[0067] Example 5

[0068]

[0069] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, 4-biphenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-1e (35% yield) and B-1e (28% yield).

[0070] A-1e: 1 H NMR (500 MHz, CDCl3) δ 8.05 (s, 1H), 7.71 - 7.65 (m, 2H), 7.60- 7.56 (m, 12H), 7.49 - 7.41 (m, 4H), 7.41 - 7.34 (m, 6H), 7.34 - 7.18 (m,4H), 7.11 - 7.02 (m, 2H), 6.96 (s, 1H). 13 C NMR (125 MHz, CDCl3) δ 160.51,160.27, 144.84, 140.22, 138.97, 138.83, 135.11, 134.16, 133.45, 132.30,129.12, 128.53, 128.43, 127.91, 127.18, 126.09, 122.82, 122.07, 118.05,116.61. HRMS-ESI: calcd [C 46 H 32 B2N6O2+H] + 723.2846; found 723.2853.

[0071] B-1e: 1H NMR (500 MHz, CDCl3) δ 8.07 (s, 1H), 7.73 - 7.68 (m, 2H), 7.61- 7.57 (m, 12H), 7.51 - 7.43 (m, 4H), 7.41 - 7.35 (m, 6H), 7.34 - 7.20 (m,4H), 7.14 - 7.05 (m, 2H), 6.98 (s, 1H). 13 C NMR (125MHz, CDCl3) δ 160.53,160.29, 144.88, 140.25, 139.01, 138.85, 135.14, 134.18, 133.48, 132.33,129.14, 128.55, 128.46, 127.93, 127.20, 126.11, 122.84, 122.11, 118.09,116.64. HRMS-ESI: calcd [C 46 H 32 B2N6O2+H] + 723.2846; found 723.2898.

[0072] Example 6

[0073]

[0074] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C and refluxed. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, 2-naphthoboric acid (2.5 mmol) was added, and the mixture was heated to 110 °C and refluxed for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-1f (yield 27%) and B-1f (yield 23%).

[0075] A-1f: 1H NMR (400 MHz, CDCl3) δ 7.97 (t, J = 2.2 Hz, 1H), 7.89 - 7.80(m, 2H), 7.76 (d, J = 8.1 Hz, 2H), 7.63 (dd, J = 7.5, 1.2 Hz, 2H), 7.57 (dd,J = 8.1, 2.1 Hz, 4H), 7.54 - 7.48 (m, 4H), 7.36 - 7.34 (m, 2H), 7.32 - 7.15(m, 3H), 7.14 – 7.10 (m, 8H). 13 C NMR (100 MHz, CDCl3) δ 159.93, 159.86,159.26, 146.01, 135.25, 134.84, 133.95, 133.53,133.55, 132.70, 131.46,130.24, 128.48, 128.45, 128.06, 128.04, 127.36, 126.94, 126.38, 122.55,122.54, 118.86, 116.59. HRMS-ESI: calcd [C 42 H 28 B2N6O2+H] + 671.2533; found671.2531.

[0076] B-1f: 1 H NMR (400 MHz, CDCl3) δ 7.95 (t, J = 2.2 Hz, 1H), 7.84 - 7.85(m, 2H), 7.77 (d, J = 8.1 Hz, 2H), 7.65 (dd, J = 7.5, 1.2 Hz, 2H), 7.55 (dd,J = 8.1, 2.1 Hz, 4H), 7.51 - 7.45 (m, 4H), 7.33 - 7.16 (m, 5H), 7.15 – 7.17(m, 8H). 13C NMR (100 MHz, CDCl3) δ 159.92, 159.84, 159.23, 146.01, 135.26,134.83, 133.93, 133.53, 132.77, 131.44, 130.28, 130.32, 128.45, 128.04,128.03, 127.33, 126.96, 126.37, 122.55, 122.55, 118.89, 116.61. HRMS-ESI:calcd [C 42 H 28 B2N6O2+H] + 671.2533; found 671.2589.

[0077] Example 8

[0078]

[0079] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, salicylaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-1 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-1 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, 2-naphthoboric acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target product A-1 g (yield 27%) and B-1 g (yield 23%).

[0080] A-1g: 1H NMR (500 MHz, CDCl3) δ 8.29 (d, J = 8.8 Hz, 1H), 7.44 – 7.42(m, 2H), 7.39 - 7.31 (m, 6H), 7.31 - 7.25 (m, 2H), 7.22 - 7.13 (m, 8H), 7.13- 7.01 (m, 5H), 6.94-6.85 (m, 4H), 6.74 - 6.68 (m, 2H), 6.30 – 6.26 (m, 1H),5.28 (dd, J = 1.9, 0.9 Hz, 1H), 4.15 - 4.13 (m, 1H), 3.89 (dd, J = 5.6, 1.0Hz, 2H), 3.77 -3.73 (m, 1H). 13 C NMR (125 MHz, CDCl3) δ 159.58, 157.76,145.34, 144.74, 140.10, 138.91, 138.01, 137.88, 137.64, 137.46, 135.65,134.96, 134.06, 133.98, 133.07, 133.01, 132.26, 131.60, 131.38, 131.33,131.00, 130.82, 129.99, 129.78, 129.71, 128.78, 127.96, 127.94, 127.47,127.45, 127.42, 126.97, 126.95, 126.58, 126.43, 126.38, 126.16, 126.04,125.67, 125.66, 125.59, 124.80, 124.77, 124.68, 122.11, 122.07, 116.54,116.37, 116.21, 114.19, 47.59, 45.84, 43.94, 30.60. HRMS-ESI: calcd[C 54 H 36 B2N6O2+H] + 823.3159; found 823.3123.

[0081] B-1g: 11H NMR (500 MHz, CDCl3) δ 8.27 (d, J = 8.8 Hz, 1H), 7.39 - 7.27 (m, 5H), 7.22 - 7.13 (m, 4H), 7.09 - 7.01 (m, 2H), 6.92 - 6.84 (m, 2H), 6.73 - 7.69 (m, 4H), 6.31 - 6.25 (m, 6H), 5.30 - 5.26 (m, 4H), 3.89 (dd, J = 5.5, 0.9 Hz, 2H), 3.77 – 7.73 (m, 6H). 13 13C NMR (125 MHz, CDCl3) δ 159.64, 159.56, 144.81, 138.91, 138.01, 137.88, 133.98, 133.07, 132.78, 131.60, 131.38, 130.82, 129.71, 128.78, 128.83, 127.94, 127.45, 126.97, 126.95, 126.16, 125.67, 125.59, 124.77, 124.68, 122.07, 116.37, 114.18, 114.13, 45.84, 30.60. HRMS-ESI: calcd [C 54 1H 36 2B6N2O2+H] + 823.3159; found 822.3152.

[0082] Example 9

[0083]

[0084] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 3-hydroxybenzothiophene-2-carboxaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-2 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-2 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-2 (25% yield) and B-2 (21% yield).

[0085] A-2: 1 H NMR (500 MHz, CDCl3) δ 8.14 (s, 1H), 7.90 (dd, J = 7.3, 1.4 Hz,4H), 7.81 (dd, J = 6.4, 1.4 Hz, 4H), 7.67 - 7.61 (m, 4H), 7.59 (s, 1H), 7.56- 7.52 (m, 2H), 7.43 - 7.34 (m, 2H), 7.34 - 7.19 (m, 6H). 13 C NMR (125 MHz, CDCl3) δ 154.23, 143.80, 143.50, 142.66, 137.71, 136.45, 136.26, 133.53,129.42, 128.62, 127.71, 127.13, 124.27, 123.60, 122.54, 122.29, 122.07,118.05. HRMS-ESI: calcd [C 38 H 24 B2N6O2S2+H] + 683.1661; found 683.1642.

[0086] B-2: 1H NMR (500 MHz, CDCl3) δ 8.16 (s, 1H), 7.92 (dd, J = 7.3, 1.4 Hz,4H), 7.83 (dd, J = 6.4, 1.4 Hz, 4H), 7.69 - 7.63 (m, 4H), 7.61 (s, 1H), 7.56- 7.52 (m, 2H), 7.45 - 7.36 (m, 2H), 7.36 - 7.21 (m, 6H). 13 C NMR (125 MHz, CDCl3) δ 156.12, 144.37, 144.52, 142.40, 138.33, 136.64, 136.35, 134.27,131.73, 129.88, 128.14, 127.86, 125.11, 124.26, 123.91, 123.49, 122.07,119.30. HRMS-ESI: calcd [C 38 H 24 B2N6O2S2+H] + 683.1661; found 683.1677.

[0087] Example 10

[0088]

[0089] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 3-hydroxybenzofuran-2-carboxaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-3 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. The above intermediate I-3 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-3 (31% yield) and B-3 (27% yield).

[0090] A-3: 11H NMR (500 MHz, CDCl3) δ 8.10 (s, 1H), 7.73 (dd, J = 9.3, 1.3 Hz, 4H), 7.68 - 7.62 (m, 4H), 7.47 - 7.34 (m, 8H), 7.34 - 7.18 (m, 6H), 6.84 (s, 1H). 13 13C NMR (125 MHz, CDCl3) δ 162.72, 155.86, 144.20, 142.58, 138.36, 136.48, 133.57, 129.83, 129.42, 129.04, 127.13, 123.30, 122.07, 119.35, 118.05, 117.72, 112.47. HRMS-ESI: calcd [C 38 1H 24 11B2N6O4+H] + 651.2118; found 651.2186.

[0091] B-3: 1 1H NMR (500 MHz, CDCl3) δ 8.10 (s, 1H), 7.73 (dd, J = 9.3, 1.3 Hz, 4H), 7.68 - 7.62 (m, 4H), 7.47 - 7.34 (m, 8H), 7.34 - 7.18 (m, 6H), 6.84 (s, 1H). 13 13C NMR (100 MHz, CDCl3) δ 163.41, 155.73, 145.39, 143.45, 139.26, 137.43, 134.72, 130.13, 129.81, 129.42, 127.34, 124.04, 123.83, 120.85, 119.46, 118.43, 113.72. HRMS-ESI: calcd [C 38 1H 24 11B2N6O4+H] + 651.2118; found 651.2163.

[0092] Example 11

[0093]

[0094] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 2-hydroxy-1-naphthaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-4 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-4 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-4a (25% yield) and B-4a (22% yield).

[0095] The chemical structural formula, single crystal structure, and crystal packing diagram of compound A-4a are shown below. Figure 1 As shown in (a), (b), and (c) in the figure; the chemical structural formula, single crystal structure, and crystal packing diagram of compound B-4a are shown in the figure. Figure 2 As shown in (a), (b) and (c) in the figure.

[0096] A-4a: 1 H NMR (400 MHz, CDCl3) δ 8.88 (s, 1H), 8.10 (d, J = 9.0 Hz, 2H), 7.87 (d, J = 8.3 Hz, 2H), 7.83 (dd, J = 8.1, 1.2 Hz, 2H), 7.64 - 7.60 (m,2H), 7.52 (d, J = 9.0 Hz, 2H), 7.48 - 7.44 (m, 2H), 7.42 - 7.38 (m, 4H), 7.13- 7.10 (m, 5H), 6.98 (dd, J = 6.0, 3.4 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ155.47, 155.43, 150.53, 141.59, 141.50, 138.57, 138.49, 131.96, 131.92,131.33, 129.18, 129.15, 128.92, 128.90, 128.49, 128.45, 128.16, 128.04,127.98, 127.68, 127.58, 124.97, 124.93, 123.77, 121.24, 120.36, 120.32,117.51, 112.29, 77.22, 53.44, 25.27. HRMS-ESI: calcd [C 34 H 24 B2N6O2+H] + 671.2533;found 671.2575.

[0097] B-4a: 1 H NMR (400 MHz, CDCl3) δ 8.87 (s, 1H), 8.08 (d, J = 9.0 Hz, 2H),7.86 (d, J = 8.3 Hz, 2H), 7.83 - 7.79 (m, 2H), 7.60 -7.56 (m, 2H), 7.52 (s,1H), 7.50 (s, 1H), 7.45 – 7.41 (m, 5H), 7.15 (dd, J = 5.0, 1.9 Hz, 6H), 6.98(dd, J = 6.0, 3.4 Hz, 2H). 13 C NMR (125 MHz, CDCl3) δ 155.49, 155.45, 150.57,150.55, 141.59, 141.50, 138.55, 138.47, 131.96, 131.92, 131.34, 129.17,129.15, 128.92, 128.89, 128.50, 128.47, 128.18, 128.16, 128.07, 128.00,127.68, 127.58, 124.96, 124.92, 123.77, 123.75, 121.23, 121.20, 120.37,120.33, 117.52, 112.31, 112.29. HRMS-ESI: calcd [C 34 H 24B2N6O2+H] + 671.2533; found 671.2538.

[0098] Example 12

[0099]

[0100] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 2-hydroxy-1-naphthaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-4 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-4 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-4b (yield 17%) and B-4b (yield 19%).

[0101] A-4b: 1 H NMR (400 MHz, CDCl3) δ 8.94 (s, 1H), 8.13 (d, J = 9.0 Hz, 2H), 7.91 (s, 1H), 7.85 (dd, J = 14.6, 8.2 Hz, 4H), 7.66 - 7.64 (m, 4H), 7.60 (dd,J = 8.6, 2.5 Hz, 6H), 7.52 (dd,J = 8.2, 1.3 Hz, 2H), 7.49 - 7.40 (m, 6H),7.36 - 7.27 (m, 4H), 6.92 (dd,J = 6.1, 3.4 Hz, 2H). 13C NMR (100 MHz, CDCl3)δ 155.42, 150.70, 141.69, 138.72, 133.43, 132.85, 131.99, 131.31, 129.22,129.17, 128.97, 128.94, 128.52, 128.01, 127.97, 127.45, 126.94, 125.59,125.40, 125.01, 123.83, 121.26, 120.31, 117.50, 112.44, 77.22. HRMS-ESI:calcd [C 50 H 32 B2N6O2+H] + 771.2846; found 771.2826.

[0102] B-4b: 1 H NMR (400 MHz, CDCl3) δ 8.92 (s, 1H), 8.11 (d, J = 9.0 Hz, 2H),7.88 (s, 1H), 7.83 (dd, J = 14.6, 8.2 Hz, 4H), 7.66 - 7.60 (m, 4H), 7.57 (dd,J = 8.6, 2.5 Hz, 6H), 7.50 (dd, J = 8.2, 1.3 Hz, 2H), 7.47 - 7.38 (m, 6H),7.33 - 7.24 (m, 4H), 6.91 (dd, J = 6.1, 3.4 Hz, 2H). 13C NMR (125 MHz, CDCl3)δ 155.55, 155.44, 150.72, 141.69, 141.60, 138.70, 138.59, 133.45, 132.89,132.87, 132.01, 131.99, 131.33, 129.22, 129.14, 129.11, 128.95, 128.91,128.52, 128.48, 128.08, 128.02, 128.00, 127.46, 127.05, 126.94, 125.59,125.40, 125.00, 124.95, 123.81, 121.23, 121.18, 120.36, 120.31, 117.58,117.51, 112.44, 112.36, 111.25, 110.07. HRMS-ESI: calcd [C 50 H 32 B2N6O2+H] + 771.2846; found 771.2801.

[0103] Example 13

[0104]

[0105] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C and refluxed. After the solid was completely dissolved, 3-hydroxyquinoline-2-carboxaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-5 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-5 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C and refluxed for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-5 (26% yield) and B-5 (21% yield).

[0106] A-5: 11H NMR (500 MHz, CDCl3) δ 8.07 (s, 1H), 7.98 - 7.90 (m, 2H), 7.85 - 7.81 (m, J = 8.3, 2.6, 1.2 Hz, 6H), 7.71 - 7.61 (m, 3H), 7.54 - 7.47 (m, 2H), 7.45 (s, 1H), 7.43 - 7.35 (m, 7H), 7.34 - 7.20 (m, 4H). 13 13C NMR (125 MHz, CDCl3) δ 160.51, 160.27, 144.84, 138.44, 135.11, 133.57, 133.45, 132.30, 129.42, 128.53, 127.13, 126.09, 122.82, 122.07, 118.05, 116.61. HRMS-ESI: calcd [C 40 H 26 B2N8O2+H] + 673.2438; found 673.2451.

[0107] B-5: 1 1H NMR (500 MHz, CDCl3) δ 8.09 (s, 1H), 8.01 - 7.93 (m, 2H), 7.88 - 7.86 (m, 6H), 7.74 - 7.63 (m, 3H), 7.57 - 7.50 (m, 2H), 7.47 (s, 1H), 7.43 - 7.41 (m, 7H), 7.36 - 7.22 (m, 4H). 13 13C NMR (101 MHz, CDCl3) δ 160.73, 160.28, 148.24, 146.17, 138.44, 137.24, 132.79, 132.21, 128.43, 127.72, 126.12, 122.79, 122.13, 118.05, 116.56, 112.37. HRMS-ESI: calcd [C 40 H 26 B2N8O2+H] + 673.2438; found 673.2447.

[0108] Example 14

[0109]

[0110] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 8-hydroxyjulonidine-9-carboxaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-6 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-6 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-6 (27% yield) and B-6 (12% yield).

[0111] A-6: 1 H NMR (500 MHz, CDCl3) δ 8.80 (s, 1H), 7.55 - 7.49 (m, 6H), 7.38- 7.16 (m, 8H), 7.15 - 7.09 (m, 8H), 3.43 - 3.37 (m, 6H), 2.88 - 2.81 (m,10H), 2.01 - 1.87 (m, 3H). 13 C NMR (125 MHz, CDCl3 ) δ 160.30, 159.14, 159.03,148.00, 146.00, 135.80, 133.53, 129.52, 129.30, 129.01, 125.23, HRMS-ESI: calcd [C 46 H 42 B2N8O2+H] + 761.3690; found 761.3691.

[0112] B-6: 1H NMR (500 MHz, CDCl3) δ 8.78 (s, 1H), δ 7.58 - 7.52 (m, 6H), 7.36 - 7.14 (m, 8H), 7.13 - 7.07 (m, 8H), 3.44 - 3.38 (m, 6H), 2.85 - 2.78 (m, 10H), 2.02 - 1.88 (m, 3H). 13 C NMR (100 MHz, CDCl3) δ 160.33, 160,12,159.04, 159.05, 147.23, 146.05, 134.75, 133.52, 128.32, 128.30, 128.01,125.22, 122.58, 121.13, 118.75, 118.57, 113.23, 113.13, 50.29, 50.28, 27.66,23.44, 22.13, 21.90, 20.85. HRMS-ESI: calcd [C 46 H 42 B2N8O2+H] + 761.3690; found 761.3604.

[0113] Example 15

[0114]

[0115] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 2-hydroxypyrene-1-carboxaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-7 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-7 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-7a (32% yield) and B-7a (27% yield).

[0116] A-7a: 1H NMR (500 MHz, CDCl3) δ 8.16 (s, 1H), 8.07 - 7.96 (m, 2H), 7.89- 7.79 (m, 2H), 7.76 - 7.67 (m, 2H), 7.59 - 7.49 (m, 4H), 7.38 - 7.16 (m,4H), 7.09 - 7.01 (m, 4H), 6.36 -7.28 (m, 8H), 5.56 - 5.46 (m, 5H), 3.93 -3.81 (m, 2H). 13 C NMR (125 MHz, CDCl3) δ 160.99, 160.82, 154.94, 146.04,145.98, 138.66, 137.04, 134.50, 133.57, 133.53, 132.58, 131.71, 130.68,130.18, 129.87, 129.65, 129.55, 129.53, 129.52, 129.33, 129.31, 129.30,129.12, 129.05, 129.01, 128.84, 128.34, 128.03, 127.79, 127.01, 126.97,126.77, 126.48, 126.14, 125.87, 125.82, 125.50, 124.88, 124.74, 123.92,123.89, 123.85, 122.59, 122.55, 121.98, 118.87, 118.86, 116.89, 109.73,46.25, 45.33, 30.30. HRMS-ESI: calcd [C 54 H 34 B2N6O2+H] + 821.3008; found 821.3021.

[0117] B-7a: 1H NMR (500 MHz, CDCl3) δ 8.18 (s, 1H), 8.05 - 7.94 (m, 2H), 7.88- 7.78 (m, 2H), 7.77 - 7.67 (m, 2H), 7.56 - 7.46 (m, 4H), 7.36 -7.14 (m, 4H), 7.08 - 7.01 (m, 4H), 6.34 - 6.26 (m, 8H), 5.54 - 5.45 (m, 5H), 3.90 - 3.78 (m, 2H). 13 C NMR (100 MHz, CDCl3) δ 160.89, 160.81, 154.91, 146.02, 145.89,138.44, 136.09, 134.25, 133.53, 132.59, 132.58, 131.61, 130.48, 130.44,129.81, 129.66, 129.54, 129.53, 129.52, 129.34, 129.33, 129.30, 129.11,129.01, 128.89, 128.84, 128.32, 128.01, 127.66, 127.01, 126.95, 126.50,126.48, 126.09, 125.89, 125.87, 125.50, 125.48, 124.84, 124.74, 123.90,123.89, 123.83, 122.57, 122.56, 121.98, 118.83, 118.80, 116.89, 109.77,31.35, 30.29. HRMS-ESI: calcd [C 54 H 34 B2N6O2+H] + 821.3008; found 821.3002.

[0118] Example 16

[0119]

[0120] In a 100 mL flask, 2,3-dihydrazinoquinoxaline (1 mmol) and ethanol (35 mL) were added sequentially, and the mixture was heated to 80 °C under reflux. After the solid was completely dissolved, 2-hydroxypyrene-1-carboxaldehyde (2.5 mmol) and concentrated hydrochloric acid (0.5 mL) were added. At this point, the reaction solution gradually darkened in color, accompanied by the formation of a precipitate. The reaction was stopped after 1 hour, and intermediate I-7 was collected by filtration under reduced pressure. This intermediate did not require further purification and was used directly in the next coordination reaction. Intermediate I-7 (1 mmol) was dispersed in toluene (35 mL), and N,N-diisopropylethylamine (1.5 mL) was added. After the system became clear, 4-(trimethylsilane)phenylboronic acid (2.5 mmol) was added, and the mixture was heated to 110 °C under reflux for 8 hours. After the reaction was completed, the reaction solution was cooled to room temperature and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography to obtain the target products A-7b (yield 44%) and B-7b (yield 37%).

[0121] A-7b: 1 H NMR (500 MHz, CDCl3) δ 9.01 (s, 1H), 8.81 (s, 1H), 8.33 (d, J= 7.7 Hz, 1H), 8.27 (dd, J = 7.5, 1.8 Hz, 1H), 8.09 - 7.95 (m, 3H), 7.95 -7.89 (m, 3H), 7.74 (dd, J = 8.0, 1.7 Hz, 1H), 7.66 - 7.60 (m, 4H), 7.13 (s,5H), 7.04 - 7.08 (m, 1H), 6.95 (dd, J = 5.5, 3.3 Hz, 2H), 6.89 - 6.83 (m,1H), 6.82 - 6.72 (m, 4H), 6.23 - 6.25 (m, 1H), 4.86 - 4.87 (m, 1H), 3.85 -3.72 (m, 2H), 0.39 (s, 18H). 13C NMR (125 MHz, CDCl3) δ 159.98, 154.27,147.04, 144.89, 142.73, 142.68, 142.36, 142.30, 139.62, 139.60, 137.04,134.54, 133.39, 133.34, 132.65, 132.63, 132.62, 132.60, 132.44, 132.43,132.41, 131.73, 131.72, 130.66, 130.64, 130.17, 128.84, 128.71, 127.88,127.78, 127.43, 126.70, 126.60, 126.47, 126.40, 125.98, 125.87, 125.82,125.21, 124.45, 123.76, 121.93, 121.89, 117.98, 117.97, 117.12, 117.08,114.25, 109.63, 46.41, 30.28, -0.85, -0.94, -1.03, -1.12. HRMS-ESI: calcd[C 60 H5B2N6O2Si2+H] + 695.3793; found 695.3790.

[0122] B-7b: 1 H NMR (500 MHz, CDCl3) δ 9.01 (s, 1H), 8.81 (s, 1H), 8.33 (d, J= 7.7 Hz, 1H), 8.27 (dd, J = 7.5, 1.8 Hz, 1H), 8.09 - 7.95 (m, 3H), 7.95 -7.89 (m, 3H), 7.74 (dd, J = 8.0, 1.7 Hz, 1H), 7.66 - 7.60 (m, 4H), 7.13 (s,5H), 7.04 - 7.08 (m, 1H), 6.95 (dd, J = 5.5, 3.3 Hz, 2H), 6.89 - 6.83 (m,1H), 6.82 - 6.72 (m, 4H), 6.23 - 6.25 (m, 1H), 4.89 - 4.90 (m, 1H), 3.85 -3.72 (m, 2H), 0.39 (s, 18H). 13C NMR (125 MHz, CDCl3) δ 159.98, 154.27,147.04, 144.89, 142.73, 142.68, 142.36, 142.30, 139.62, 139.60, 137.04,134.54, 133.39, 133.34, 132.65, 132.63, 132.62, 132.60, 132.44, 132.43,132.41, 131.73, 131.72, 130.66, 130.64, 130.17, 128.84, 128.71, 127.88,127.78, 127.43, 126.70, 126.60, 126.47, 126.40, 125.98, 125.87, 125.82,125.21, 124.45, 123.76, 121.93, 121.89, 117.98, 117.97, 117.12, 117.08,114.25, 109.63, 46.41, 30.28, -0.85, -0.94, -1.03, -1.12. HRMS-ESI: calcd[C 60 H5B2N6O2Si2+H] + 695.3793; found 695.3766.

[0123] Performance tests were performed on some of the products from the above embodiments.

[0124] This invention employs a slow solvent diffusion method to cultivate single crystals of the target compound to confirm its precise spatial configuration. Specifically, the pure A-4a or B-4a obtained by column chromatography in Example 11 is dissolved in dichloromethane to prepare a near-saturated solution. After filtration through a microporous membrane, the solution is transferred into a clean single crystal tube. Hexane is then added very slowly along the tube wall as a poor solvent, creating a clear liquid-liquid interface between the good and poor solvents. The container is then sealed and placed in a constant-temperature, light-proof, and vibration-proof environment. After 3 to 7 days of solvent interdiffusion, transparent, blocky single crystals with regular geometric shapes precipitate on the tube wall or bottom. Single crystals of suitable size are then selected for X-ray single-crystal diffraction testing and structural analysis.

[0125] Single-crystal structure analysis confirmed that the BOSQUIs dye is based on an N,O-type six-membered chelate ring structure formed by the 2,3-dihydrazinoquinoxaline ligand and the central boron atom, with the boron atoms exhibiting a typical tetrahedral coordination geometry. As shown in Figure 1, the two axial benzene rings of A-4a are located on the same side of the quinoxaline core plane, arranged in a cis configuration, exhibiting a confined saddle-shaped topology. Strong π-π interactions exist between the dimer molecules, with conjugated planes coupling with an overlap of up to 50% and an interlayer spacing of 3.45 Å. This highly overlapping "parallel sandwich" stacking greatly promotes nonradiative transitions between excitons, leading to severe fluorescence quenching. In contrast, the trans-isomer B-4a shown in Figure 2 adopts a step-like dislocation stacking, with significant dislocation between molecules, resulting in a significantly reduced conjugated plane overlap of 19% and an increased average interlayer spacing of 3.53 Å. This "loose" and interlaced arrangement effectively suppresses concentration quenching and restricts intramolecular rotation in the aggregated state, thus endowing the trans isomer with excellent aggregation-induced emission (AIE) effect.

[0126] Weigh out each target organoboron dye compound (A-4a, B-4a, A-4b, B-6b, A-6a, B-6a), dissolve and quantitatively dilute them in spectroscopically pure dichloromethane to prepare a solution with a concentration of 1.0 × 10⁻⁶. -5 The test solution M was used. Absorption spectra were measured using a JASCO V-670 UV-Vis spectrophotometer, emission spectra were measured using a HITACHI F-4700 fluorescence spectrometer, and fluorescence quantum efficiency was measured using a Quantaurus-QY Plus UV-NIR absolute quantum efficiency meter. The efficiency was calculated using the formula SS = λ. em max −λ abs max The Stokes shifts of each dye were calculated, and the results are shown in Table 1.

[0127] Table 1. Representative organoboron dyes in dichloromethane solution (concentration 10). -5 Photophysical properties in )

[0128]

[0129] As shown in Table 1 and Figure 3, the maximum absorption peaks (λ) of compounds A-4a, B-4a, A-4b, and B-4b are... abs max The emission peak is concentrated at 493–514 nm, corresponding to the maximum emission peak (λ). em maxLocated in the 594–597 nm region, these dyes exhibit remarkably large Stokes shifts (SS), generally exceeding 100 nm (e.g., A-4a reaches 104 nm), far superior to conventional planar BF2 fluorescent molecules (e.g., BODIPY, ~10 nm). The large SS effectively avoids overlap between excitation and emission spectra, completely eliminating fluorescence self-absorption interference, thus greatly improving the accuracy and sensitivity of optical detection. The fluorescence quantum yield (Φ) of these dyes in dilute DCM solutions is... F The initial background luminescence is extremely low, almost "silent". This ultra-large Stokes shift, combined with extremely low initial background luminescence, not only effectively avoids the fluorescence self-absorption effect, but also lays the physical foundation for subsequent high signal-to-noise ratio environmental response imaging.

[0130] To investigate the luminescence enhancement characteristics of BOSQUIs dyes in the aggregated state, this invention uses A-4a and B-4a as examples to examine the influence of the cis and trans configurations of these organoboron dyes on AIE behavior. As shown in Figure 4, in the THF / H2O mixed system, A-4a and A-4b show almost no luminescence in pure THF; with the increase of the undesirable solvent (water) volume fraction (f... w As the concentration increased from 10% to 50%, the fluorescence intensity of the cis-configuration A-4a exhibited a significant monotonic decreasing trend, and at f w When f = 50%, it drops to its lowest point, exhibiting typical aggregation-induced quenching (ACQ) characteristics, attributed to the nonradiative transition of excitons induced by the tight π-π packing of the cis isomers in the early stages of aggregation. w When the concentration is further increased to over 60%, the fluorescence intensity rebounds and slightly exceeds the initial intensity due to the intramolecular restricted irradiation (RIR) effect becoming dominant, exhibiting weak AIE activity. In contrast, the trans configuration B-4b exhibits a significantly different performance advantage. With f w As the concentration increased from 10% to 70%, the fluorescence intensity showed a significant upward trend, with a maximum enhancement factor approaching 10-fold. This significant improvement stemmed from the wider interlayer spacing (3.53 Å) and extremely low orbital overlap (19%) of the trans configuration, effectively suppressing concentration quenching in the aggregated state and achieving efficient radiative attenuation through rotational restriction of axial groups in a space-constrained environment. w Once the aggregate size exceeds 70%, the fluorescence intensity decreases due to severe Mie scattering or kinetic precipitation caused by excessive aggregate size growth.

[0131] To further verify the effect of environmental viscosity on the excited-state deactivation pathway, this invention investigated the fluorescence response characteristics of BOSQUIs dyes in a glycerol / methanol (Glycerol / MeOH) mixed solvent system.Figure 5 As shown, the cis-A-4a and trans-A-4b isomers exhibit consistent viscosity-response behavior, with their fluorescence intensity monotonically increasing with increasing medium viscosity, and showing increasing intensity at glycerol volume fraction f. g The intensity peaks at 70% and 80%, followed by a signal decline due to excessive aggregate size growth or precipitation. This cross-configurational response synchronicity strongly confirms the dominant role of intramolecular motion-restricted mechanisms in the luminescence enhancement process: increased environmental viscosity suppresses the free rotation of axial aryl groups around single bonds through hydrodynamic resistance, thereby significantly blocking non-radiative energy transition channels. This characteristic endows the dye with great application potential in lipid droplet imaging. By utilizing the high-viscosity and strongly hydrophobic microenvironment inside the lipid droplet to synergistically trigger AIE and viscosity response, high-contrast in-situ "on" imaging under a "silent" polar cytoplasmic background is achieved.

[0132] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details and technical features in the above embodiments. Without contradicting the spirit of the present invention, simple modifications and arbitrary combinations can be made to the technical solutions of the present invention, which should also be regarded as the content disclosed by the present invention.

Claims

1. A quinoxalinyl organoboron dye, characterized in that, Its structural formula is shown below: Among them, Ar 1 Ar 2 Each is independently selected from substituted or unsubstituted C6-C. 30 Aromatic groups, substituted or unsubstituted C3-C 30 One of the heteroaryl groups.

2. The quinoxalin-based organoboron dye according to claim 1, characterized in that, Ar 1 Each is independently selected from one of the following: benzene ring, benzothiophene ring, benzofuran ring, naphthalene ring, juulonidin ring, quinoline ring, pyrene ring, or derivatives thereof; Ar 2 Each is independently selected from one of phenyl, thiophene, furanyl, pyridyl, biphenyl, naphthyl, pyrene, or their derivatives.

3. A method for preparing a quinoxalin-based organoboron dye as described in claim 1 or 2, characterized in that, The preparation method includes the following steps: Step (1): Add 2,3-dihydrazinoquinoxaline to the first solvent, dissolve it, add aromatic aldehyde or its derivative, add acid to react, and obtain intermediate N,O type ligand I; Step (2): Dissolve intermediate N,O type ligand I in a second solvent, add alkali and organoboronic acid compound to react and obtain the quinoxalin-based organoboronic dye; 。 4. The preparation method according to claim 3, characterized in that, The molar ratio of 2,3-dihydrazinoquinoxaline to aromatic aldehydes or their derivatives is 1:(2.0~3.0); the molar ratio of intermediate N,O type ligand I to organoboronic acid compounds is 1:(2.0~5.0).

5. The preparation method according to claim 3, characterized in that, The first solvent and the second solvent are each independently selected from one or more of methanol, ethanol, isopropanol, dichloromethane, chloroform, 1,2-dichloroethane, toluene, xylene, chlorobenzene, tetrahydrofuran, 1,4-dioxane, acetonitrile, N,N-dimethylformamide, or dimethyl sulfoxide.

6. The preparation method according to claim 3, characterized in that, The acid includes organic or inorganic acids; the organic acid is selected from one or more of acetic acid, trifluoroacetic acid, p-toluenesulfonic acid, or trifluoromethanesulfonic acid; the inorganic acid is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid.

7. The preparation method according to claim 3, characterized in that, The base includes an organic base or an inorganic base; the organic base is selected from one or more of triethylamine, N,N-diisopropylethylamine, pyridine, 4-dimethylaminopyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene or 1,5-diazabicyclo[4.3.0]non-5-ene; the inorganic base is selected from one or more of sodium carbonate, potassium carbonate, cesium carbonate, sodium bicarbonate, sodium hydroxide or potassium hydroxide.

8. The preparation method according to claim 3, characterized in that, The reaction temperature in step (1) is 80°C and the reaction time is 8~10 h; the reaction temperature in step (2) is 110°C and the reaction time is 6~8 h.

9. The use of the quinoxalin-based organoboron dyes as described in claim 1 or 2 in bioimaging, fluorescence sensing, photodynamic therapy, or photothermal therapy.

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