A linear nitrogenous D-A type nonlinear optical material, a preparation method and application thereof

Abstract

The application discloses a linear nitrogen hetero D-A type nonlinear optical material and a preparation method and application thereof. Pyrazine is a leading functional material due to easy synthesis and flexible structural modification, and pyrazine has strong electron-deficient characteristics, and is usually connected with a pi-linker to form a push-pull system conducive to intramolecular interaction. The application takes pyrazine as a central electron acceptor unit, introduces different electron-withdrawing and electron-donating pi-linkers at one end to increase or weaken the electron-withdrawing property of the parent, and connects different electron-donating groups at the other end through Suzuki coupling to form a linear structure, thereby enhancing the intramolecular charge transfer capability, and better nonlinear optical performance is generated. The technical scheme adopted by the application is that the application provides a formula (PZ) shown in the formula (PZ), wherein R1 is methoxy, H, cyano or nitro, and R2 is bromo, triarylamine or methoxyphenyl.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a linear nitrogen-doped DA-type nonlinear optical material, its preparation method, and its application. Background Technology

[0002] Early research on nonlinear optical materials began with inorganic crystals. However, inorganic crystals suffer from unavoidable drawbacks, such as susceptibility to deliquescence leading to damage, and the inability to function as single-crystal materials, hindering their application in nonlinear optics. Organic nonlinear optical materials, on the other hand, possess advantages such as molecular design and tailoring, high response values, fast switching speeds, high optical damage thresholds, superior mechanical strength, low dielectric constants, and excellent processing performance. Furthermore, they hold significant application potential in image processing, all-optical switching, optical storage, and memory systems. Therefore, the synthesis of novel organic third-order nonlinear optical materials with excellent optical properties, thermal stability, and processing performance is currently a very active research area.

[0003] Pyrazine compounds possess excellent biological and pharmaceutical activities and are widely used in organic synthesis and drug research. Furthermore, pyrazines have become a leading class of functionalized materials due to their ease of synthesis and flexible structural modification. Pyrazines also exhibit strong electron-deficient properties, often forming push-pull systems with π-linkers that facilitate intramolecular interactions, thus possessing good optical properties. They can be used in photosensitizers, fluorescent probes, and nonlinear optical materials. By using pyrazine as the central electron acceptor unit, introducing different electron-withdrawing and electron-donating π-linkers at one end to increase or decrease the parent compound's electron-withdrawing properties, and then connecting different electron-donating groups at the other end via Suzuki coupling, a linear structure is formed, enhancing intramolecular charge transfer capabilities and creating a push-pull system within the molecule. This significantly improves the third-order nonlinear optical properties of the molecule. Summary of the Invention

[0004] The purpose of this invention is to provide a linear azide DA-type nonlinear optical material, its preparation method, and its application. Based on the molecular structure characteristics of organic third-order nonlinear optical materials, this invention designs a linear structure with pyrazine as the central electron acceptor unit, introduces different electron-withdrawing and electron-donating π-connectors at one end to increase or decrease the electron-withdrawing property of the parent material, and connects different electron-donating groups at the other end through Suzuki coupling to form a linear structure, thereby enhancing the intramolecular charge transfer capability and producing better nonlinear optical performance. A series of organic third-order nonlinear optical materials with excellent optical properties have been obtained.

[0005] The technical solution adopted in this invention is:

[0006] This invention provides a class of linear nitrogen-doped DA-type nonlinear optical materials, characterized in that the structural formula of the linear nitrogen-doped DA-type nonlinear optical material is shown in formula (PZ).

[0007]

[0008] In formula (PZ): R1 is methoxy, H, cyano, or nitro, and R2 is triarylamine or methoxyphenyl.

[0009] The preferred structural formula of the linear nitrogen-doped DA-type third-order nonlinear optical material is as follows:

[0010]

[0011]

[0012]

[0013]

[0014] A second objective of this invention is to provide a method for synthesizing the above-mentioned linear nitrogen-doped DA-type nonlinear optical material with the structural formula shown in formula (PZ), the synthesis method comprising the following steps:

[0015] (1) Suzuki coupling reaction

[0016] Under nitrogen protection, 2,5-dibromopyrazine of formula (I) and 4-bromophenylboronic acid of formula (II) were added to solvent A. Under the action of base A and palladium catalyst Pd(PPh3)4, the Suzuki coupling reaction was carried out at 60-90℃ to obtain 2,5-di(4-bromophenyl)pyrazine of formula (III).

[0017]

[0018] Preferably, in step (1), the molar ratio of 2,5-dibromopyrazine (Formula I) and 4-bromophenylboronic acid (Formula II) is 1:2 to 1:4. In step (1), solvent A is a mixture of toluene, ethanol, and water, with a volume mixing ratio of 8–12:2–4:0.5–1.5. The catalyst is tetrakis(triphenylphosphine)palladium Pd(PPh3)4; the base A is potassium carbonate, potassium bicarbonate, sodium carbonate, or sodium bicarbonate. In step (1), the molar ratio of 2,5-dibromopyrazine (Formula I), 4-bromophenylboronic acid (Formula II), palladium catalyst, and base A is 1:2–4:0.1–0.5:6–9.

[0019] (2) Suzuki coupling reaction

[0020] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (Formula III) and 5-formaldehyde-furan-2-boronic acid (Formula IV) were added to solvent B. Under the action of base B and palladium catalyst Pd(PPh3)4, a Suzuki coupling reaction was carried out at 60-100 °C to obtain the monosubstituted formaldehyde-furan pyrazine compound (Formula V).

[0021]

[0022] Preferably, the molar ratio of 2,5-bis(4-bromophenyl)pyrazine (Formula (III)) to 5-formaldehyde-furan-2-boric acid (Formula (IV)) is 1:0.8 to 1:1.3. In step (2), solvent B is a mixture of tetrahydrofuran and water, with a volume mixing ratio of 5:1 to 2:1. The catalyst is tetrakis(triphenylphosphine)palladium Pd(PPh3)4; the base B is potassium carbonate, potassium bicarbonate, sodium carbonate, or sodium bicarbonate. In step (2), the molar ratio of 2,5-bis(4-bromophenyl)pyrazine (Formula (III)) to 5-formaldehyde-furan-2-boric acid (Formula (IV)), palladium catalyst, and base B is 1:0.8 to 1.2:0.1 to 0.5:6 to 9.

[0023] (3) Condensation reaction

[0024] The monosubstituted formaldehyde-based furanylpyrazine compound shown in formula (V) and 4-methoxy-o-phenylenediamine, o-phenylenediamine, 3,4-diaminobenzonitrile, and 4-nitro-o-phenylenediamine were added to solvent C and subjected to a condensation reaction at 60–90 °C under the action of salt C to obtain the linear aza-DA type benzimidazole derivative shown in formula (PZ-Br).

[0025]

[0026] Preferably, in step (3), the solvent C is a mixture of ethanol and water with a volume mixing ratio of 10:1 to 8:1, and the salt C is sodium pyrosulfate.

[0027] (4) Suzuki coupling reaction

[0028] Under nitrogen protection, the linear aza-DA type benzimidazole derivative shown in formula (PZ-Br) and 4-boronic acid triphenylamine or 4-methoxyboronic acid were added to solvent D, and a Suzuki coupling reaction was carried out at 60-100 °C under the action of base D and palladium catalyst Pd(PPh3)4 to obtain the compound shown in formula (PZ).

[0029]

[0030] In formula (PZ): R1 is methoxy, H, cyano, or nitro, and R2 is bromo, triarylamine, or methoxyphenyl.

[0031] Preferably, the molar ratio of the linear aza-DA type benzimidazole derivative represented by formula (PZ-Br) to triphenylamine 4-boronate or 4-methoxyboronic acid is 1:1 to 1:5. In step (4), the solvent D is a mixture of tetrahydrofuran and water, with a volume mixing ratio of 5:1 to 2:1. The catalyst is tetrakis(triphenylphosphine)palladium Pd(PPh3)4, and the base D is potassium carbonate, potassium bicarbonate, sodium carbonate, or sodium bicarbonate. In step (4), the molar ratio of the linear aza-DA type benzimidazole derivative represented by formula (PZ-Br) to triphenylamine 4-boronate or 4-methoxyboronic acid, the palladium catalyst, and the base D is 1:1 to 5:0.1 to 0.5:6 to 9.

[0032] A third objective of this invention is to provide the application of the linear nitrided DA-type nonlinear optical material in nonlinear optics.

[0033] The beneficial effects of this invention are:

[0034] By attaching a benzene ring to each side of the pyrazine as the center, the chain length is increased, the overall π-conjugated system is expanded, and the intramolecular charge transfer is made more free. Introducing a furan ring as a π bridge at one end of the benzene ring can further expand the overall π-conjugated system. On the other hand, the furan ring, as an electron-donating group, can form a simple D-π-A electron-donating and electron-withdrawing system with the electron-withdrawing group of pyrazine, which has the effect of pushing and pulling electrons.

[0035] Subsequently, the aldehyde group introduced at one end of the furanaldehyde group undergoes a condensation reaction with o-phenylenediamine derivatives containing different electron-withdrawing and electron-donating groups to form benzimidazole derivatives. Firstly, benzimidazole has a rigid structure and a large π-conjugated plane, thus it can function as both an acceptor and a co-donor, as well as a π-bridge, and exhibits excellent charge transport properties within the molecule. Introducing a strong electron-withdrawing nitro group or a relatively strong electron-withdrawing cyano group at one end of the benzimidazole significantly enhances the electron-withdrawing ability of the acceptor end, lowering the LUMO level. Conversely, introducing an electron-donating methoxy group or a relatively weak electron-donating H group at one end of the benzimidazole significantly enhances the electron-donating ability of the acceptor end, raising the HOMO level and lowering the band gap. Due to the varying strengths of the electron-withdrawing and electron-donating abilities of the introduced groups, they increase the overall electron push-pull effect of the molecule to varying degrees, and the nonlinear properties of the molecule are also improved to varying degrees.

[0036] Simultaneously, introducing different electron-donating groups at the other end of the compound enhances the overall electron-donating and electron-absorbing system. We found that the introduction of groups with strong electron-donating capabilities, such as triphenylamine and methoxyphenyl, increased the HOMO level and further reduced the band gap, significantly improving the nonlinear properties of the molecule. These compounds exhibit excellent third-order nonlinear optical properties and show great potential for applications in nonlinear optical devices. Attached Figure Description

[0037] Figure 1 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZ-1) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0038] Figure 2 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZ-2) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0039] Figure 3 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZ-3) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0040] Figure 4 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZ-4) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0041] Figure 5 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZS-1) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0042] Figure 6 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZS-2) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0043] Figure 7 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZS-3) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0044] Figure 8 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZS-4) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0045] Figure 9 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZJ-1) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0046] Figure 10The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZJ-2) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0047] Figure 11 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZJ-3) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0048] Figure 12 The normalized open-pore Z-scan curve of the linear aza-DA type benzimidazole derivative (PZJ-4) in DMF is shown, where the black hollow dots are laboratory data and the solid line is fitted data.

[0049] Figure 13 The 400MHz 1H NMR spectrum of compound (PZ-1) obtained in Example 1 of this invention;

[0050] Figure 14 The 400MHz 1H NMR spectrum of compound (PZ-2) obtained in Example 2 of this invention;

[0051] Figure 15 The 400MHz 1H NMR spectrum of compound (PZ-3) obtained in Example 3 of this invention;

[0052] Figure 16 The 400MHz 1H NMR spectrum of compound (PZ-4) obtained in Example 4 of this invention;

[0053] Figure 17 The 400MHz 1H NMR spectrum of compound (PZS-1) obtained in Example 5 of this invention;

[0054] Figure 18 The 400MHz 1H NMR spectrum of compound (PZS-2) obtained in Example 6 of this invention;

[0055] Figure 19 The 400MHz 1H NMR spectrum of compound (PZS-3) obtained in Example 7 of this invention;

[0056] Figure 20 The 1H NMR spectrum of compound (PZS-4) obtained in Example 8 of this invention is shown at 400 MHz.

[0057] Figure 21 The 400MHz 1H NMR spectrum of compound (PZJ-1) obtained in Example 9 of this invention;

[0058] Figure 22The 400MHz 1H NMR spectrum of compound (PZJ-2) obtained in Example 10 of this invention;

[0059] Figure 23 The 400MHz 1H NMR spectrum of compound (PZJ-3) obtained in Example 11 of this invention;

[0060] Figure 24 The 400MHz 1H NMR spectrum of compound (PZJ-4) obtained in Example 12 of this invention;

[0061] Figure 25 A photograph of the compound (PZ-1) obtained in Example 1 of this invention;

[0062] Figure 26 Here is a physical image of the compound (PZ-2) obtained in Example 2 of this invention;

[0063] Figure 27 A photograph of the compound (PZ-3) obtained in Example 3 of this invention;

[0064] Figure 28 A photograph of the compound (PZ-4) obtained in Example 4 of this invention;

[0065] Figure 29 This is a physical image of the compound (PZS-1) obtained in Example 5 of the present invention;

[0066] Figure 30 A photograph of the compound (PZS-2) obtained in Example 6 of this invention;

[0067] Figure 31 A photograph of the compound (PZS-3) obtained in Example 7 of this invention;

[0068] Figure 32 A photograph of the compound (PZS-4) obtained in Example 8 of this invention;

[0069] Figure 33 A photograph of the compound (PZJ-1) obtained in Example 9 of this invention;

[0070] Figure 34 A photograph of the compound (PZJ-2) obtained in Example 10 of this invention;

[0071] Figure 35 A photograph of the compound (PZJ-3) obtained in Example 11 of this invention;

[0072] Figure 36 This is a physical image of the compound (PZJ-4) obtained in Example 12 of the present invention. (I) Detailed Implementation

[0073] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0074] Example 1

[0075] (1) Suzuki coupling reaction

[0076] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (6.02 g, 30 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 32 mL toluene, 8 mL anhydrous ethanol, and 2 mL water were added to a flask. The reaction temperature was raised to 60 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 2.91 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 50% (based on the molar amount of the compound).

[0077]

[0078] (2) Suzuki coupling reaction

[0079] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0080]

[0081] (3) Condensation reaction

[0082] A monosubstituted formaldehyde-based furazolidone compound (0.5 g, 1.24 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 4-methoxy-o-phenylenediamine (0.17 g, 1.24 mmol) and sodium sulfite (0.95 g, 4.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.32 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-1), was obtained, with a yield of 49.4% (based on the molar amount of the compound).

[0083]

[0084] Example 2

[0085] (1) Suzuki coupling reaction

[0086] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (12.05 g, 60 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 24 mL toluene, 6 mL anhydrous ethanol, and 3 mL water were added to a flask. The reaction temperature was raised to 100 °C, and the reaction was stirred for 24 h before being stopped. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.07 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 70% (based on the molar amount of the compound).

[0087]

[0088] (2) Suzuki coupling reaction

[0089] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0090]

[0091] (3) Condensation reaction

[0092] A monosubstituted formaldehyde-based furazolidone compound (0.4 g, 0.99 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with o-phenylenediamine (0.11 g, 0.99 mmol) and sodium sulfite (0.76 g, 3.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.225 g of a linear aza-DA type benzimidazole derivative, as shown in formula (PZ-2), was obtained, with a yield of 46% (based on the molar amount of the compound).

[0093]

[0094] Example 3

[0095] (1) Suzuki coupling reaction

[0096] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0097]

[0098] (2) Suzuki coupling reaction

[0099] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (1.49 g, 10.65 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 50 mL tetrahydrofuran, and 10 mL water were added to a flask. The reaction temperature was raised to 60 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 1.61 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 30% (based on the molar amount of the compound).

[0100]

[0101] (3) Condensation reaction

[0102] A monosubstituted formaldehyde-based furazolidone compound (0.5 g, 1.24 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 3,4-diaminobenzonitrile (0.17 g, 1.24 mmol) and sodium sulfite (0.95 g, 4.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.32 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-3), was obtained, with a yield of 49.9% (based on the molar amount of the compound).

[0103]

[0104] Example 4

[0105] (1) Suzuki coupling reaction

[0106] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0107]

[0108] (2) Suzuki coupling reaction

[0109] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 30 mL of water were added to a flask. The reaction temperature was raised to 100 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 2.47 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 46% (based on the molar amount of the compound).

[0110]

[0111] (3) Condensation reaction

[0112] A monosubstituted formaldehyde-based furanylpyrazine compound (0.4 g, 0.99 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 4-nitro-o-phenylenediamine (0.15 g, 0.99 mmol) and sodium sulfite (0.76 g, 3.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.23 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-4), was obtained, with a yield of 43.1% (based on the molar amount of the compound).

[0113]

[0114] Example 5

[0115] (1) Suzuki coupling reaction

[0116] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0117]

[0118] (2) Suzuki coupling reaction

[0119] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0120]

[0121] (3) Condensation reaction

[0122] A monosubstituted formaldehyde-based furazolidone compound (0.5 g, 1.24 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 4-methoxy-o-phenylenediamine (0.17 g, 1.24 mmol) and sodium sulfite (0.95 g, 4.96 mmol). The mixture was stirred at 60 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.32 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-1), was obtained, with a yield of 49.4% (based on the molar amount of the compound).

[0123]

[0124] (4) Suzuki coupling reaction

[0125] Under nitrogen protection, 0.15 g (0.29 mmol) of the linear aza-DA type benzimidazole derivative (PZ-1), 0.33 g (1.15 mmol) of triphenylamine 4-borate, 0.02 g (0.02 mmol) of tetra(triphenylphosphine)palladium Pd(PPh3)4, 0.12 g (0.86 mmol) of potassium carbonate, 2.25 mL of tetrahydrofuran, and 0.75 mL of water were added to a flask. The reaction temperature was raised to 90 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.05 g of the linear aza-DA type benzimidazole derivative (PZS-1) was obtained as a brown solid powder, with a yield of 25.3%. (Based on the amount of substance of the compound).

[0126]

[0127] Example 6

[0128] (1) Suzuki coupling reaction

[0129] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0130]

[0131] (2) Suzuki coupling reaction

[0132] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0133]

[0134] (3) Condensation reaction

[0135] A monosubstituted formaldehyde-based furazolidone compound (0.4 g, 0.99 mmol) was dissolved in 8 mL of ethanol and 1 mL of water with o-phenylenediamine (0.11 g, 0.99 mmol) and sodium sulfite (0.76 g, 3.96 mmol). The mixture was stirred at 90 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.225 g of a linear aza-DA type benzimidazole derivative, as shown in formula (PZ-2), was obtained, with a yield of 46% (based on the molar amount of the compound).

[0136]

[0137] (4) Suzuki coupling reaction

[0138] Under nitrogen protection, 0.15 g (0.3 mmol) of the linear aza-DA type benzimidazole derivative (PZ-2), 0.35 g (1.22 mmol) of triphenylamine 4-borate, 0.02 g (0.02 mmol) of tetra(triphenylphosphine)palladium Pd(PPh3)4, 0.13 g (0.91 mmol) of potassium carbonate, 2.25 mL of tetrahydrofuran, and 0.75 mL of water were added to a flask. The reaction temperature was raised to 90 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.03 g of the linear aza-DA type benzimidazole derivative (PZS-2) was obtained as a yellow solid powder, with a yield of 15%. (Based on the amount of substance of the compound).

[0139]

[0140] Example 7

[0141] (1) Suzuki coupling reaction

[0142] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0143]

[0144] (2) Suzuki coupling reaction

[0145] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0146]

[0147] (3) Condensation reaction

[0148] A monosubstituted formaldehyde-based furazolidone compound (0.5 g, 1.24 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 3,4-diaminobenzonitrile (0.17 g, 1.24 mmol) and sodium sulfite (0.95 g, 4.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.32 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-3), was obtained, with a yield of 49.9% (based on the molar amount of the compound).

[0149]

[0150] (4) Suzuki coupling reaction

[0151] Under nitrogen protection, 0.1 g (0.19 mmol) of the linear aza-DA type benzimidazole derivative (PZ-3), 0.05 g (0.19 mmol) of triphenylamine 4-borate, 0.01 g (0.01 mmol) of tetra(triphenylphosphine)palladium Pd(PPh3)4, 0.08 g (0.58 mmol) of potassium carbonate, 1 mL of tetrahydrofuran, and 1 mL of water were added to a flask. The reaction temperature was raised to 60 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.08 g of the linear aza-DA type benzimidazole derivative (PZS-3) was obtained as a brown solid powder, with a yield of 60.8% (based on the molar amount of the compound).

[0152]

[0153] Example 8

[0154] (1) Suzuki coupling reaction

[0155] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0156]

[0157] (2) Suzuki coupling reaction

[0158] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0159]

[0160] (3) Condensation reaction

[0161] A monosubstituted formaldehyde-based furanylpyrazine compound (0.4 g, 0.99 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 4-nitro-o-phenylenediamine (0.15 g, 0.99 mmol) and sodium sulfite (0.76 g, 3.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.23 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-4), was obtained, with a yield of 43.1% (based on the molar amount of the compound).

[0162]

[0163] (4) Suzuki coupling reaction

[0164] Under nitrogen protection, 0.07 g (0.13 mmol) of the linear aza-DA type benzimidazole derivative (PZ-4), 0.19 g (0.65 mmol) of triphenylamine 4-borate, 0.01 g (0.01 mmol) of tetra(triphenylphosphine)palladium Pd(PPh3)4, 0.05 g (0.39 mmol) of potassium carbonate, 2 mL of tetrahydrofuran, and 1 mL of water were added to a flask. The reaction temperature was raised to 100 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.05 g of the linear aza-DA type benzimidazole derivative (PZS-4) was obtained as a reddish-brown solid powder, with a yield of 52.5%. (Based on the amount of substance of the compound).

[0165]

[0166] Example 9

[0167] (1) Suzuki coupling reaction

[0168] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0169]

[0170] (2) Suzuki coupling reaction

[0171] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0172]

[0173] (3) Condensation reaction

[0174] A monosubstituted formaldehyde-based furazolidone compound (0.5 g, 1.24 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 4-methoxy-o-phenylenediamine (0.17 g, 1.24 mmol) and sodium sulfite (0.95 g, 4.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.32 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-1), was obtained, with a yield of 49.4% (based on the molar amount of the compound).

[0175]

[0176] (4) Suzuki coupling reaction

[0177] Under nitrogen protection, 0.1 g (0.19 mmol) of the linear aza-DA type benzimidazole derivative (PZ-1), 0.12 g (0.77 mmol) of 4-methoxyphenylboronic acid, 0.01 g (0.01 mmol) of tetrakis(triphenylphosphine)palladium Pd(PPh3)4, 0.08 g (0.57 mmol) of potassium carbonate, 2.25 mL of tetrahydrofuran, and 0.75 mL of water were added to a flask. The reaction temperature was raised to 90 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.06 g of the linear aza-DA type benzimidazole derivative (PZJ-1) was obtained as a brown solid powder, with a yield of 55.5%. (Based on the amount of substance of the compound).

[0178]

[0179] Example 10

[0180] (1) Suzuki coupling reaction

[0181] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0182]

[0183] (2) Suzuki coupling reaction

[0184] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0185]

[0186] (3) Condensation reaction

[0187] A monosubstituted formaldehyde-based furazolidone compound (0.4 g, 0.99 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with o-phenylenediamine (0.11 g, 0.99 mmol) and sodium sulfite (0.76 g, 3.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.225 g of a linear aza-DA type benzimidazole derivative, as shown in formula (PZ-2), was obtained, with a yield of 46% (based on the molar amount of the compound).

[0188]

[0189] (4) Suzuki coupling reaction

[0190] Under nitrogen protection, 0.1 g (0.2 mmol) of the linear aza-DA type benzimidazole derivative (PZ-2), 0.12 g (0.81 mmol) of 4-methoxyphenylboronic acid, 0.01 g (0.01 mmol) of tetrakis(triphenylphosphine)palladium Pd(PPh3)4, 0.08 g (0.61 mmol) of potassium carbonate, 2.25 mL of tetrahydrofuran, and 0.75 mL of water were added to a flask. The reaction temperature was raised to 90 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.06 g of the linear aza-DA type benzimidazole derivative (PZJ-2) was obtained as a yellow-brown solid powder, with a yield of 56.8%. (Based on the amount of substance of the compound).

[0191]

[0192] Example 11

[0193] (1) Suzuki coupling reaction

[0194] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0195]

[0196] (2) Suzuki coupling reaction

[0197] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0198]

[0199] (3) Condensation reaction

[0200] A monosubstituted formaldehyde-based furazolidone compound (0.5 g, 1.24 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 3,4-diaminobenzonitrile (0.17 g, 1.24 mmol) and sodium sulfite (0.95 g, 4.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.32 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-3), was obtained, with a yield of 49.9% (based on the molar amount of the compound).

[0201]

[0202] (4) Suzuki coupling reaction

[0203] Under nitrogen protection, 0.1 g (0.19 mmol) of the linear aza-DA type benzimidazole derivative (PZ-3), 0.12 g (0.77 mmol) of 4-methoxyphenylboronic acid, 0.01 g (0.01 mmol) of tetrakis(triphenylphosphine)palladium Pd(PPh3)4, 0.08 g (0.58 mmol) of potassium carbonate, 2.25 mL of tetrahydrofuran, and 0.75 mL of water were added to a flask. The reaction temperature was raised to 90 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.07 g of the linear aza-DA type benzimidazole derivative (PZJ-3) was obtained as a blackish-brown solid powder, with a yield of 66.5%. (Based on the amount of substance of the compound).

[0204]

[0205] Example 12

[0206] (1) Suzuki coupling reaction

[0207] Under nitrogen protection, 2,5-dibromopyrazine (3.55 g, 15 mmol), 4-bromophenylboronic acid (9.04 g, 45 mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.87 g, 0.75 mmol), potassium carbonate (4.15 g, 30 mmol), 50 mL toluene, 10 mL anhydrous ethanol, and 5 mL water were added to a flask. The reaction temperature was raised to 75 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (V(petroleum ether) / V(ethyl acetate) = 10 / 1) to give 4.26 g of 2,5-di(4-bromophenyl)pyrazine, with a yield of 73% (based on the molar amount of the compound).

[0208]

[0209] (2) Suzuki coupling reaction

[0210] Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine (5.19 g, 13.31 mmol), 5-carboxymethylfuran-2-boronic acid (2.23 g, 16 mmol), tetra(triphenylphosphine)palladium Pd(PPh3)4 (0.77 g, 0.67 mmol), potassium carbonate (5.01 g, 39.92 mmol), 60 mL of tetrahydrofuran, and 20 mL of water were added to a flask. The reaction temperature was raised to 85 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction solution was quenched in 500 mL of saturated brine, and then extracted with 300 mL of dichloromethane. The filtrate was evaporated to dryness, and the solid was purified by silica gel column chromatography (pure dichloromethane) to give 3.3 g of the monosubstituted carboxymethylfuranpyrazine compound of formula (V), with a yield of 61% (based on the molar amount of the compound).

[0211]

[0212] (3) Condensation reaction

[0213] A monosubstituted formaldehyde-based furanylpyrazine compound (0.4 g, 0.99 mmol) was dissolved in 12 mL of ethanol and 1.2 mL of water with 4-nitro-o-phenylenediamine (0.15 g, 0.99 mmol) and sodium sulfite (0.76 g, 3.96 mmol). The mixture was stirred at 80 °C for 24 h, and then the reaction was stopped. The reaction solution was poured into 150 mL of saturated brine, and the solid was allowed to precipitate completely. The mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane. After drying the filter cake, 0.23 g of a linear aza-DA type benzimidazole derivative, represented by formula (PZ-4), was obtained, with a yield of 43.1% (based on the molar amount of the compound).

[0214]

[0215] (4) Suzuki coupling reaction

[0216] Under nitrogen protection, 0.1 g (0.19 mmol) of the linear aza-DA type benzimidazole derivative (PZ-4), 0.11 g (0.74 mmol) of 4-methoxyphenylboronic acid, 0.01 g (0.01 mmol) of tetrakis(triphenylphosphine)palladium Pd(PPh3)4, 0.07 g (0.56 mmol) of potassium carbonate, 2.25 mL of tetrahydrofuran, and 0.75 mL of water were added to a flask. The reaction temperature was raised to 90 °C, and the reaction was stopped after stirring for 24 h. After cooling, the reaction was stopped, and the reaction solution was poured into 150 mL of saturated brine. After the solid completely precipitated, the mixture was filtered, and the filter cake was washed with 100 mL of dichloromethane, then washed with 5 mL of tetrahydrofuran. After drying the filter cake, 0.05 g of the linear aza-DA type benzimidazole derivative (PZJ-4) was obtained as a brown solid powder, with a yield of 47.6%. (Based on the amount of substance of the compound).

[0217]

[0218] Example 13

[0219] Third-order nonlinear optical performance testing:

[0220] The third-order nonlinear optical properties of the compound (PZ-1)-(PZJ-4) described in this invention were tested using Z-scan technology.

[0221] The laser used in the test was an Amode-locked Nd:YAG 532nm laser, the energy probe was an Rj-7620ENERGYRATIOMETER, the laser pulse energy was 5μJ, the wavelength was 532nm, and the pulse width was 7ps;

[0222] Sample testing: The sample was prepared into a DMF solution with a concentration of 0.3 mg / mL and placed in a quartz cuvette with a thickness of 2 mm. The incident laser beam was focused into the quartz cuvette by a 300 mm focal length lens. The beam waist radius at the focal point was 30 mm and the Raleigh length was 3 mm. The linear transmittance T0 was measured to be 76%.

[0223] The test results are shown in Table 1. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 Table 1 shows the third-order nonlinear parameters of linear aza-DA type benzimidazole derivatives. Figure 1The experimental data and fitting curves for the third-order nonlinearity of compound PZ-1 are shown. Compounds PZ-1, PZ-2, PZ-3, PZ-4, PZS-1, PZS-2, PZS-3, PZS-4, PZJ-1, PZJ-2, PZJ-3, and PZJ-4 all exhibit anti-saturation absorption.

[0224] Table 1 shows the third-order nonlinear data parameters of linear aza-DA type benzimidazole derivatives (PZ) in DMF.

[0225] Table 1: Third-order nonlinear parameters of linear aza-DA type benzimidazole derivatives (PZ)

[0226]

[0227] Table 1

[0228] Example 14

[0229] Nuclear magnetic resonance hydrogen spectrum testing:

[0230] Sample testing: Using deuterated DMSO as the deuterated solvent, the sample was prepared into a solution with a concentration of 2 mg / mL, then transferred into a clean NMR tube, the tube opening was sealed, and then NMR testing was performed.

[0231] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as these technical features do not contradict each other, they should be considered to be within the scope of this specification.

[0232] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A linear nitrogen-doped DA-type nonlinear optical material, characterized in that, The structural formula of the linear nitrogen-doped DA-type nonlinear optical material is as follows: 。 2. The method for preparing linear nitrogen-doped DA-type nonlinear optical materials as described in claim 1, characterized in that, Includes the following steps: (1) Under nitrogen protection, 2,5-dibromopyrazine of formula (I) and 4-bromophenylboronic acid of formula (II) were added to solvent A. Under the action of base A and palladium catalyst Pd(PPh3)4, the Suzuki coupling reaction was carried out at 60-90℃ to obtain 2,5-di(4-bromophenyl)pyrazine of formula (III). (2) Under nitrogen protection, 2,5-bis(4-bromophenyl)pyrazine of formula (III) and 5-formaldehyde-furan-2-boric acid of formula (IV) were added to solvent B. Under the action of base B and palladium catalyst Pd(PPh3)4, the Suzuki coupling reaction was carried out at 60-100℃ to obtain the monosubstituted formaldehyde-furan pyrazine compound of formula (V). (3) The monosubstituted formaldehyde-based furan pyrazine compound shown in formula (V) and 4-methoxy-o-phenylenediamine, o-phenylenediamine, 3,4-diaminobenzonitrile, and 4-nitro-o-phenylenediamine were added to solvent C and condensed at 60-90°C under the action of salt C to obtain the linear aza-DA type benzimidazole derivative shown in formula (PZ-Br); (4) Under nitrogen protection, the linear aza-DA type benzimidazole derivative shown in formula (PZ-Br) and 4-boronic acid triphenylamine or 4-methoxyboronic acid are added to solvent D, and Suzuki coupling reaction is carried out at 60-100℃ under the action of base D and palladium catalyst Pd(PPh3)4 to obtain the compound shown in formula (PZS) or the compound shown in formula (PZJ). ； The compounds represented by formula (PZS) and formula (PZJ) are specifically PZ-1, PZ-2, PZ-3, PZ-4, PZS-1, PZS-2, PZS-3, PZS-4, PZJ-1, PZJ-2, PZJ-3, or PZJ-4.

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of 2,5-dibromopyrazine represented by formula (I) and 4-bromophenylboronic acid represented by formula (II) is 1:2 to 1:4; In step (1), solvent A is a mixture of toluene, ethanol, and water, with a volume mixing ratio of 8-12:2-4:0.5-1.5; In step (1), the catalyst is tetra(triphenylphosphine)palladium, and the base A is potassium carbonate, potassium bicarbonate, sodium carbonate, or sodium bicarbonate. In step (1), the molar ratio of 2,5-dibromopyrazine (I), 4-bromophenylboronic acid (II), catalyst, and base A is 1:2-4:0.1-0.5:6-9.

4. The preparation method according to claim 2, characterized in that, In step (2), the molar ratio of 2,5-bis(4-bromophenyl)pyrazine represented by formula (III) and 5-formaldehyde-furan-2-boronic acid represented by formula (IV) is 1:0.8 to 1:1.3; In step (2), solvent B is a mixture of tetrahydrofuran and water, with a volume mixing ratio of 5:1 to 2:1; In step (2), the catalyst is tetra(triphenylphosphine)palladium, the base B is potassium carbonate, potassium bicarbonate, sodium carbonate, or sodium bicarbonate, and the molar ratio of 2,5-bis(4-bromophenyl)pyrazine (Formula III) and 5-formaldehyde-furan-2-boric acid (Formula IV), the catalyst, and base B is 1:0.8-1.2:0.1-0.5:6-9.

5. The preparation method according to claim 2, characterized in that, In step (3), the solvent C is a mixture of ethanol and water, with a volume mixing ratio of 10:1 to 8:1; In step (3), the salt C is sodium pyrosulfate.

6. The preparation method according to claim 2, characterized in that, In step (4), the molar ratio of the linear aza-DA type benzimidazole derivative represented by formula (PZ-Br) to triphenylamine 4-boronic acid or 4-methoxyboronic acid is 1:1 to 1:5; In step (4), the solvent D is a mixture of tetrahydrofuran and water, with a volume mixing ratio of 5:1 to 2:1; In step (4), the catalyst is tetra(triphenylphosphine)palladium, and the base D is potassium carbonate, potassium bicarbonate, sodium carbonate, or sodium bicarbonate. In step (4), the molar ratio of the linear aza-DA type benzimidazole derivative represented by formula (PZ-Br) to triphenylamine 4-boronic acid or 4-methoxyboronic acid, the catalyst and base D is 1:1 to 5:0.1 to 0.5:6 to 9.

7. The application of the linear nitrogen-doped DA-type nonlinear optical material as described in any one of claims 1 to 6 in the fabrication of nonlinear optical devices.

Images