A Y-type benzimidazole third-order nonlinear optical material and its preparation method and application

Abstract

The present invention discloses a Y-type benzimidazole third-order nonlinear optical material and its preparation method and application. The benzimidazole molecule has a conjugated large π plane structure and also has a plurality of modifiable active sites. The present invention uses benzimidazole as a matrix, introduces an electron-withdrawing group at one end to increase the electron-withdrawing property of the matrix, and connects different electron-donating groups at the other end through Suzuki coupling to form a Y-type, thereby enhancing the charge transfer capability within the molecule and producing better nonlinear optical performance. The technical solution adopted by the present invention is: the present invention provides a type of formula (DEN): #imgabs0# In the formula (DEM): R1 is a nitro group or a cyano group, and R2 is a triarylamine group or a phenyl group.

Description

Technical Field

[0001] The invention belongs to the technical field of new materials, and specifically relates to a Y-type benzimidazole third-order nonlinear optical material and a preparation method and application thereof. Background Art

[0002] In the early days, people explored and studied nonlinear optical materials from inorganic crystal materials. However, inorganic crystal materials are easily damaged by deliquescence, can only work in the form of single crystal materials, and are difficult to achieve optical integration. These unavoidable disadvantages limit their application in the field of nonlinear optics. Organic nonlinear optical materials have the advantages of molecular design and tailoring, high response value, fast switching speed, high optical damage threshold, excellent mechanical strength, low dielectric constant, and good processing performance. They also have great application potential in the fields of image processing, all-optical switching, optical storage and memory systems, etc. Therefore, the synthesis of new organic third-order nonlinear optical materials with excellent optical properties, thermal stability and processing performance is currently a very active research field.

[0003] Benzimidazole compounds have good biological and pharmaceutical activities and are widely used in organic synthesis and drug research. In addition, benzimidazole can be used as both an electron-withdrawing group and an auxiliary receptor. Its rigid planar structure and large conjugated system give it good optical properties and can be used in the fields of photosensitizers, fluorescent probes, and nonlinear optical materials. Benzimidazole has many modifiable sites. By connecting different groups to the benzimidazole mother ring, it can promote intramolecular charge transfer and increase the π conjugated system of the entire molecule, forming a push-pull system structure within the molecule, which is very helpful in improving the third-order nonlinear optical properties of the molecule. Summary of the invention

[0004] The purpose of the present invention is to provide a Y-type benzimidazole third-order nonlinear optical material and a preparation method and application thereof. According to the molecular structure characteristics of the organic third-order nonlinear optical material, the present invention designs a series of organic third-order nonlinear optical materials with excellent optical properties by taking benzimidazole as the parent ring, introducing p-nitrophenyl or p-cyanophenyl as the electron-withdrawing group, and introducing phenyl or triphenylamine as the electron-donating group on the parent ring.

[0005] The technical solution adopted by the present invention is:

[0006] The present invention provides a Y-type benzimidazole-based third-order nonlinear optical material, characterized in that the Y-type benzimidazole-based third-order nonlinear optical material has a structural formula as shown in formula (DEM),

[0007]

[0008] In the formula (DEM), R1 is a nitro group or a cyano group, and R2 is a triphenylamine group or a phenyl group.

[0009] The Y-type benzimidazole third-order nonlinear optical material preferably has the following structural formula:

[0010]

[0011]

[0012] The second object of the present invention is to provide a method for synthesizing the above-mentioned Y-type benzimidazole third-order nonlinear optical material (compound represented by formula DEM), the synthesis method comprising the following steps:

[0013] (1) Condensation reaction

[0014] In acetic acid as a solvent, 4,5-dibromobenzene-1,2-diamine represented by formula (I) is subjected to a condensation reaction with p-nitrobenzaldehyde or p-cyanobenzaldehyde at 100-150° C. to obtain a dibromo compound represented by formula (II);

[0015]

[0016] (2) Suzuki coupling reaction

[0017] Under nitrogen protection, the dibromo compound represented by formula (II) is added to solvent A, and under the action of base A and palladium catalyst Pd(PPh3)4, it undergoes Suzuki coupling reaction with phenylboric acid or triphenylamine-4-boric acid at 60-100°C to obtain a benzimidazole derivative represented by formula (DEM);

[0018]

[0019] In the formula (DEM), R1 is a nitro group or a cyano group, and R2 is a triphenylamine group or a phenyl group.

[0020] Preferably, the solvent in step (1) is acetic acid, the molar ratio of 4,5-dibromobenzene-1,2-diamine represented by formula (I) to p-nitrobenzaldehyde or p-cyanobenzaldehyde is 1:0.9-1, and the volumetric amount of the organic solvent is 10-30 mL / g based on the mass of 4,5-dibromobenzene-1,2-diamine represented by formula (I).

[0021] Preferably, the solvent A in step (2) is toluene, ethanol, and water, and the volume mixing ratio is 8-12:4-6:0.5-1.5, and more preferably 10:5:1; the palladium catalyst is tetrakis(triphenylphosphine)palladium Pd(PPh3)4; the base A is potassium carbonate, potassium bicarbonate, sodium carbonate, and sodium bicarbonate; the molar ratio of the dibromo compound represented by formula (II), phenylboric acid or triphenylamine-4-boric acid, palladium catalyst and base A is 1:2-4:0.1-0.3:6-9; the volume dosage of the organic solvent is 20-50 mL / g based on the mass of the dibromo compound represented by formula (II);

[0022] The third object of the present invention is to provide application of the Y-type benzimidazole third-order nonlinear optical material in nonlinear optics.

[0023] Beneficial effects of the present invention:

[0024] The introduction of a strong electron-withdrawing group, nitro, at one end of benzimidazole greatly improves the electron-withdrawing ability of the acceptor part and reduces the LUMO energy level. At the same time, the introduction of different electron-donating groups at the other end of the compound enhances the electron-donating system of the entire compound. We found that when groups with strong electron-donating ability such as triphenylamine were introduced, the HOMO energy level was increased, the energy band gap was reduced, and the nonlinear performance of the molecule was improved. This series of compounds has excellent third-order nonlinear optical properties and has great potential in the application of nonlinear optical devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the normalized open-pore Z-scan curve of Y-type benzimidazole derivative (DEM-1) in chloroform, where the black hollow points are laboratory data and the solid line is the fitting data;

[0026] Figure 2 is the normalized open-pore Z-scan curve of Y-type benzimidazole derivative (DEM-3) in chloroform, where the black hollow points are laboratory data and the solid line is the fitting data;

[0027] Figure 3 is the normalized open-pore Z-scan curve of Y-type benzimidazole derivative (DEM-3) in chloroform, where the black hollow points are laboratory data and the solid line is the fitting data;

[0028] Figure 4 is the normalized open-pore Z-scan curve of Y-type benzimidazole derivative (DEM-3) in chloroform, where the black hollow points are laboratory data and the solid line is the fitting data;

[0029] Figure 5 is the hydrogen nuclear magnetic resonance spectrum of the compound DEM-1 obtained in Example 1 of the present invention;

[0030] Figure 6 This is the hydrogen nuclear magnetic resonance spectrum of the compound DEM-2 obtained in Example 2 of the present invention;

[0031] Figure 7 This is the hydrogen nuclear magnetic resonance spectrum of the compound DEM-3 obtained in Example 3 of the present invention;

[0032] Figure 8 This is the hydrogen nuclear magnetic resonance spectrum of the compound DEM-4 obtained in Example 4 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0034] Example 1

[0035] (1) Condensation reaction

[0036] 4,5-Dibromobenzene-1,2-diamine (0.3233 g, 1.2 mmol) and p-nitrobenzaldehyde (0.1676 g, 1.1 mmol) were dissolved in 20 mL of acetic acid. After stirring at 120° C. for 12 h, the reaction was stopped and the reaction solution was poured into 150 mL of saturated brine. After the solid was completely precipitated, it was filtered and the filter cake was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 15 / 1) to obtain 0.3349 g of yellow solid powder DEM-a with a yield of 76%.

[0037]

[0038] (2) Suzuki coupling reaction

[0039] Under nitrogen protection, dibromo compound DEM-a (0.1g, 0.25mmol), triarylamine-4-boric acid (0.2183g, 0.75mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.0582g, 0.05mmol), potassium carbonate (0.2781g, 2.00mmol), 20ml toluene, 10ml anhydrous ethanol and 2ml water were added to a flask. The reaction temperature was raised to 95°C, and the reaction was stopped after stirring for 24h. After cooling, the reaction solution was poured into 100mL saturated saline solution for quenching, and then extracted with 200ml dichloromethane. The filtrate was spin-dried, and the solid was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 20 / 1) to obtain 0.1124g of reddish brown benzimidazole derivative DEM-1, with a yield of 62% (based on the amount of the compound).

[0040]

[0041] Example 2

[0042] (1) Condensation reaction

[0043] 4,5-Dibromobenzene-1,2-diamine (0.3233 g, 1.2 mmol) and p-nitrobenzaldehyde (0.1676 g, 1.1 mmol) were dissolved in 20 mL of acetic acid. After stirring at 120° C. for 12 h, the reaction was stopped and the reaction solution was poured into 150 mL of saturated brine. After the solid was completely precipitated, it was filtered and the filter cake was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 15 / 1) to obtain 0.3349 g of yellow solid powder DEM-a with a yield of 76%.

[0044]

[0045] (2) Suzuki coupling reaction

[0046] Under nitrogen protection, dibromo compound DEM-a (0.1g, 0.25mmol), phenylboronic acid (0.0922g, 0.75mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.0582g, 0.05mmol), potassium carbonate (0.2781g, 2.00mmol), 20ml toluene, 10ml anhydrous ethanol and 2ml water were added to a flask. The reaction temperature was raised to 95°C, and the reaction was stopped after stirring for 24h. After cooling, the reaction solution was poured into 100mL saturated saline solution for quenching, and then extracted with 200ml dichloromethane. The filtrate was spin-dried, and the solid was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 20 / 1) to obtain 0.04g of red benzimidazole derivative DEM-2, with a yield of 41% (based on the amount of the compound).

[0047]

[0048] Example 3

[0049] (1) Condensation reaction

[0050] 4,5-Dibromobenzene-1,2-diamine (0.3233 g, 1.2 mmol) and p-nitrobenzaldehyde (0.1453 g, 1.1 mmol) were dissolved in 20 mL of acetic acid. After stirring at 120° C. for 12 h, the reaction was stopped and the reaction solution was poured into 150 mL of saturated brine. After the solid was completely precipitated, it was filtered and the filter cake was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 10 / 1) to obtain 0.3128 g of light yellow solid powder DEM-b with a yield of 68%.

[0051]

[0052] (2) Suzuki coupling reaction

[0053] Under nitrogen protection, dibromo compound DEM-b (0.1g, 0.27mmol), triarylamine-4-boric acid (0.2299g, 0.79mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.0613g, 0.05mmol), potassium carbonate (0.2928g, 2.12mmol), 20ml toluene, 10ml anhydrous ethanol and 2ml water were added to a flask. The reaction temperature was raised to 95°C, and the reaction was stirred for 24h before stopping. After cooling, the reaction solution was poured into 100mL saturated saline solution for quenching, and then extracted with 200ml dichloromethane. The filtrate was spin-dried, and the solid was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 15 / 1) to obtain 0.1172g of brown benzimidazole derivative DEM-3, with a yield of 82% (based on the amount of the compound).

[0054]

[0055] Example 4

[0056] (1) Condensation reaction

[0057] 4,5-Dibromobenzene-1,2-diamine (0.3233 g, 1.2 mmol) and p-nitrobenzaldehyde (0.1453 g, 1.1 mmol) were dissolved in 20 mL of acetic acid. After stirring at 120° C. for 12 h, the reaction was stopped and the reaction solution was poured into 150 mL of saturated brine. After the solid was completely precipitated, it was filtered and the filter cake was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 10 / 1) to obtain 0.3128 g of light yellow solid powder DEM-b with a yield of 68%.

[0058]

[0059] (2) Suzuki coupling reaction

[0060] Under nitrogen protection, dibromo compound DEM-b (0.1g, 0.27mmol), phenylboronic acid (0.0971g, 0.79mmol), tetrakis(triphenylphosphine)palladium Pd(PPh3)4 (0.0613g, 0.05mmol), potassium carbonate (0.2928g, 2.12mmol), 20ml toluene, 10ml anhydrous ethanol and 2ml water were added to a flask. The reaction temperature was raised to 95°C, and the reaction was stirred for 24h before stopping. After cooling, the reaction solution was poured into 100mL saturated saline solution for quenching, and then extracted with 200ml dichloromethane. The filtrate was dried and the solid was purified by silica gel column chromatography (V (petroleum ether) / V (ethyl acetate) = 10 / 1) to obtain 0.0514g of milky white benzimidazole derivative DEM-4, with a yield of 43% (based on the amount of the compound).

[0061]

[0062] Example 5

[0063] Third-order nonlinear optical performance test:

[0064] The third-order nonlinear optical properties of the compounds DEM-1 to DEM-4 described in the present invention are tested using a Z-scan technique.

[0065] The laser used in the test is a mode-locked Nd:YAG532 nm laser, the energy probe is Rj-7620ENERGY RATIOMETER, the laser pulse energy is 30μJ, the wavelength is 532nm, and the pulse width is 4ns;

[0066] Sample test: The sample was prepared into a chloroform 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 of the focal spot was 30 μm, the Raleigh length was 3 mm, and the measured linear transmittance T0 was 86%.

[0067] The test results are shown in Table 1. Figure 1 , Figure 2 , Figure 3 and Figure 4 , Table 1 shows the third-order nonlinear parameters of Y-type benzimidazole derivatives, Figure 1 These are the third-order nonlinear experimental data and fitting curves of compound DEM-1. DEM-1 is an anti-saturation absorption, and compounds DEM-2, DEM-3, and DEM-4 are all anti-saturation absorption.

[0068] Table 1 is the third-order nonlinear data parameters of Y-type benzimidazole derivatives (DEM) in chloroform

[0069] Table 1: Third-order nonlinear parameters of Y-type benzimidazole derivatives (DEM)

[0070]

[0071] The technical features of the above-described embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there are no contradictions in these technical features, they should be considered to be within the scope of this specification.

[0072] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A Y-type benzimidazole third-order nonlinear optical material, characterized in that: The Y-type benzimidazole third-order nonlinear optical material has the following structural formula:

2. A method for preparing the Y-type benzimidazole third-order nonlinear optical material according to claim 1, characterized in that: The steps include: (1) Condensation reaction In acetic acid as a solvent, 4,5-dibromobenzene-1,2-diamine represented by formula (I) is subjected to a condensation reaction with p-nitrobenzaldehyde or p-cyanobenzaldehyde at 100-150° C. to obtain a dibromo compound represented by formula (II); (2) Suzuki coupling reaction Under nitrogen protection, the dibromo compound represented by formula (II) is added to solvent A, and under the action of base A and palladium catalyst Pd(PPh3)4, Suzuki coupling reaction is carried out with phenylboric acid or triarylamine-4-boric acid at 60-110°C to obtain benzimidazole derivatives represented by formula (DEM-1), (DEM-2), (DEM-3), (DEM-4); Among them, R1 in formula (II) corresponds to the groups in (DEM-1), (DEM-2), (DEM-3) and (DEM-4).

3. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of 4,5-dibromobenzene-1,2-diamine represented by formula (II) to p-nitrobenzaldehyde or p-cyanobenzaldehyde is 1:0.9-1.

4. The preparation method according to claim 2, characterized in that: In step (2), the solvent A is a mixture of toluene, ethanol and water, and the volume mixing ratio is 8-12:4-6:0.5-1.

5.

5. The preparation method according to claim 2, characterized in that: In step (2), the catalyst is tetrakis(triphenylphosphine)palladium Pd(PPh3)4; The base A is potassium carbonate or potassium bicarbonate or sodium carbonate or sodium bicarbonate.

6. The preparation method according to claim 5, characterized in that: In step (2), the molar ratio of the dibromo compound represented by formula (II), phenylboronic acid or triarylamine-4-boric acid, palladium catalyst and base A is 1:2-4:0.1-0.3:6-9.

7. Use of the Y-type benzimidazole third-order nonlinear optical material according to any one of claims 1 to 6 in the preparation of nonlinear optical devices.

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