An electron donor-acceptor type organic conjugated polymer, its preparation method and application

Abstract

The present invention discloses an electron donor-acceptor type organic conjugated polymer, a preparation method thereof and an application. The electron donor-acceptor type organic conjugated polymer has a structural formula shown in the following formula I: wherein: R is selected from a straight-chain alkyl group or a branched-chain alkyl group; x is a positive integer selected from 1 to 10; each independently represents an aromatic group having an electron-donating ability or an electron-withdrawing ability. In the structure of the electron donor-acceptor type organic conjugated polymer, due to its large conjugated structure and strong donor-acceptor interaction, the material exhibits excellent intramolecular charge transfer absorption; the introduction of the heavy metal atom platinum (II) in its conjugated backbone, the spin-orbit coupling generated by the heavy atom effect enables the singlet excited state of the material to undergo intersystem crossing to form a triplet excited state, further improving the absorption of the excited state of the material, thereby obtaining high-performance nonlinear optical properties and realizing the application in laser limiting at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of nonlinear optical materials. More specifically, it relates to an electron donor-acceptor type organic conjugated polymer, its preparation method and application. Background Art

[0002] While lasers are applied in laser cutting, laser display, laser communication, etc., the threat of high-intensity lasers to the human eye and various optoelectronic sensors is becoming increasingly serious. Based on the nonlinear optical effect, when a low-intensity laser irradiates the material, it shows linear transmission, and the transmittance does not change with the increase of the laser intensity; when the laser intensity increases to a certain value (i.e., the limiting threshold), the material shows nonlinear transmission, and the transmittance decreases with the increase of the laser intensity. Such materials have the characteristics of "high resistance and low pass" for lasers, so they can be used as laser protection materials to protect the human eye and optoelectronic sensor devices from the damage of strong lasers.

[0003] Due to its high nonlinear optical coefficient, low limiting threshold, and easy adjustment of the response band through chemical structure, organic nonlinear optical materials have important application prospects in laser limiting. Different from inorganic nonlinear optical materials, the nonlinear optical properties of organic nonlinear optical materials mainly come from the absorption of the excited state. However, usually the excited states of organic compounds are all singlet excited states, which have short lifetimes and are not conducive to the nonlinear optical properties of the materials. Summary of the Invention

[0004] Based on the above facts, the purpose of the present invention is to provide an electron donor-acceptor type organic conjugated polymer, its preparation method and application. In the structure of the electron donor-acceptor type organic conjugated polymer provided in the present invention, due to its large conjugated structure and strong donor-acceptor interaction, the material exhibits excellent intramolecular charge transfer absorption; the introduction of the heavy metal atom platinum (II) in its conjugated backbone, the spin-orbit coupling generated by the heavy atom effect enables the singlet excited state of the material to undergo intersystem crossing to form a triplet excited state, further improving the absorption of the material in the excited state, thereby enabling the material to obtain high-performance nonlinear optical properties and realizing its application in laser limiting at the same time.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides an electron donor-acceptor type organic conjugated polymer, and the polymer has a structural formula shown in the following formula I:

[0007]

[0008] Wherein:

[0009] The R is selected from a straight-chain alkyl or a branched-chain alkyl;

[0010] x is selected from positive integers from 1 to 10;

[0011] The each independently represents an aromatic group having an electron-donating ability or an electron-withdrawing ability.

[0012] Furthermore, the one of them is selected from and the other one of them is selected from

[0013] wherein, the * represents the connection point between the group and the # represents the connection point between and the group.

[0014] In addition, it should be noted that in the above group, the N in one selected from is connected to Pt; in one selected from on the aromatic ring, C is connected to Pt.

[0015] By constructing an electron donor-acceptor conjugate system and introducing heavy metal atoms, the present invention can effectively promote the charge transfer absorption in the molecule. At the same time, due to the heavy metal atom effect, the singlet excited state is converted into a long-lived triplet excited state through intersystem crossing, generating effective triplet excited state absorption, and then a high-performance nonlinear optical material is obtained.

[0016] Furthermore, the straight-chain alkyl group is selected from -C n H 2n+1 . Exemplary straight-chain alkyl groups include but are not limited to those selected from -(CH 2 ) 5 CH 3 , -(CH 2 ) 6 CH 3 , -(CH 2 ) 7 CH 3 , -(CH 2 ) 9 CH 3 , -(CH 2 ) 10 CH 3 or -(CH 2 ) 11 CH 3 and the like.

[0017] Furthermore, the branched-chain alkyl group is selected from Exemplary branched-chain alkyl groups include but are not limited to those selected from One of the following.

[0018] Wherein, y, n, and m are each independently selected from positive integers of 1 - 14.

[0019] In another aspect, the present invention provides a method for preparing the electron donor - acceptor type organic conjugated polymer as described above, and the preparation method includes the following steps:

[0020] Mix the compound shown in Formula II

[0021]

[0022] with potassium tetrachloroplatinate, heat under reflux for reaction, and then reflux the intermediate obtained by suction filtration after the reaction with acetylacetone under alkaline conditions to obtain the compound shown in Formula III

[0023]

[0024] Dissolve the compound shown in Formula III and the compound shown in Formula IV

[0025]

[0026] in a solvent, and heat for reaction under a catalyst, alkaline conditions, and an inert atmosphere, and then separate and purify to obtain the electron donor - acceptor type organic conjugated polymer;

[0027] Wherein, the definitions of and R are as shown above respectively;

[0028] R′ is selected from or -B(OH) 2 . At this time, in R′, B is used as a linking group to combine with other groups.

[0029] Furthermore, the molar ratio of the compound shown in Formula II to potassium tetrachloroplatinate is 2.5:1 - 2.0:1.

[0030] Furthermore, the molar ratio of the intermediate to acetylacetone is 1:4 - 1:5.

[0031] Furthermore, the molar ratio of the compound shown in Formula III to the compound shown in Formula IV is 1:1 - 1:1.2.

[0032] Furthermore, the reaction temperature of the compound shown in Formula III and the compound shown in Formula IV is 80 - 120 °C.

[0033] Furthermore, the compound shown in Formula II is prepared by a method including the following steps:

[0034] Couple the monobromo-substituted aryl with arylboronic acid, and then subject the resulting product to bromination reaction to obtain the compound shown in Formula II; or

[0035] Couple the p-bromo-substituted aryl with p-bromoarylboronic acid to obtain the compound shown in Formula II.

[0036] Furthermore, the synthetic route of the compound shown in Formula II is as shown in the following formula:

[0037]

[0038] Among them, the above each independently selected from one of them.

[0039] Furthermore, the method of the bromination reaction includes: reacting the product obtained from the coupling reaction with N-bromosuccinimide.

[0040] Furthermore, the molar ratio of the monobromo-substituted aryl to arylboronic acid is 1:1 - 1:1.2.

[0041] Furthermore, the molar ratio of the p-bromo-substituted aryl to p-bromoarylboronic acid is 1:1 - 1:1.2.

[0042] Even further, the preparation method of the compound shown in Formula II includes the following steps:

[0043] Mix the monobromo-substituted aryl, arylboronic acid and catalyst, dissolve them in tetrahydrofuran and water under a nitrogen atmosphere and alkaline conditions, heat and reflux at 60 - 80 °C for 12 - 24 hours; after cooling to room temperature, extract three times with dichloromethane, combine the organic phases, wash three times with distilled water, then dry with anhydrous sodium sulfate and remove the solvent, and separate by column chromatography to obtain the intermediate product M';

[0044] Dissolve the intermediate product M' in N,N-dimethylformamide, cool it to 0 °C in an ice bath; dropwise add the N,N-dimethylformamide solution of N-bromosuccinimide, after the addition is complete, react at room temperature overnight; pour the reaction into ice water, extract three times with dichloromethane, combine the organic phases and wash three times with distilled water, dry with anhydrous sodium sulfate and then rotary evaporate to remove the solvent, and separate by column chromatography to obtain the compound shown in Formula II.

[0045] Furthermore, the molar ratio of the monobromo-substituted aryl, arylboronic acid and catalyst is 1:1:0.01 - 1:1.2:0.05.

[0046] Furthermore, the synthetic route of preparing the compound shown in Formula III from the compound shown in Formula II is as shown in the following formula:

[0047]

[0048] Furthermore, the method for preparing the compound shown in Formula III from the compound shown in Formula II includes the following steps:

[0049] Place the compound shown in Formula II and potassium tetrachloroplatinate in a two-necked flask, add 2-ethoxyethanol and water under nitrogen protection, heat under reflux with stirring for 12 - 24 h; after cooling to room temperature, filter by suction, wash the solid with water and ethanol three times in sequence, and dry in vacuo to obtain the intermediate;

[0050] Take the intermediate and place it in a two-necked flask, add 2,4-pentanedione and 2-ethoxyethanol under nitrogen protection, heat under reflux with stirring for 12 - 24 h under alkaline conditions; after the reaction solution is cooled to room temperature, pour it into water, extract with dichloromethane three times, combine the organic layers and wash with water three times; after drying over anhydrous sodium sulfate, rotary evaporate to remove the solvent, and separate by column chromatography or recrystallization to obtain the compound shown in Formula III.

[0051] Further, the synthetic route for preparing the compound shown in Formula I by reacting the compound shown in Formula III with the compound shown in Formula IV is as shown in the following formula:

[0052]

[0053] Further, the method for preparing the compound shown in Formula I by reacting the compound shown in Formula III with the compound shown in Formula IV includes the following steps:

[0054] Place the compound shown in Formula III, the compound shown in Formula IV, a catalyst and a catalytic amount of methyltrioctylammonium chloride in a Schlenk tube, add a solvent and an alkaline solution. The solution displaces nitrogen during the freeze-thaw cycle, and is placed in an oil bath and heated with stirring for 24 - 48 h; stop the reaction and restore to room temperature, pour the reaction solution into methanol and stir for 1 - 3 h, then filter out the solid; purify the solid with a Soxhlet extractor, and remove a small amount of monomer, oligomer and catalyst with methanol, acetone and n-hexane in sequence; extract the product with chloroform and add it to methanol for precipitation, and dry the filtered solid in vacuo at 40 - 60 °C for 24 - 48 h to obtain the product.

[0055] Further, the temperature of the coupling reaction is 60 - 100 °C and the time is 24 - 48 h.

[0056] Further, the catalyst is selected from one of bis(triphenylphosphine)palladium(II) dichloride, tris(o-tolyl)phosphine or tetrakis(triphenylphosphine)palladium(0).

[0057] Further, the inert atmosphere is a nitrogen atmosphere.

[0058] Further, the alkaline condition is an aqueous solution containing sodium carbonate or potassium carbonate.

[0059] Further, in the alkaline condition, the concentration of the alkaline substance is preferably 2 mol / L. -1 .

[0060] Further, the solvent is selected from one of toluene, xylene or tetrahydrofuran.

[0061] On the other hand, the present invention provides a nonlinear optical material prepared from the electron donor-acceptor type organic conjugated polymer as described above.

[0062] On the other hand, the present invention provides the application of the nonlinear optical material as described above in laser limiting.

[0063] Further, in the application, the laser used is a pulsed laser; the pulse width of the pulsed laser is 4 - 8 ns, the pulse frequency is 10 Hz, and the wavelength is 532 nm.

[0064] The beneficial effects of the present invention are as follows:

[0065] The electron donor-acceptor type organic conjugated polymer provided in the present invention has nonlinear optical properties and can be used as a nonlinear optical material. In its structure, the main chain is a copolymerization product of a benzodithiophene derivative monomer and a platinum(II) organic compound monomer. It not only has large conjugated π electrons, a strong donor-acceptor structure to promote intramolecular charge transfer, but also has the heavy atom effect of platinum(II) atoms. The three produce a synergistic effect, making the material have a large third-order nonlinear coefficient, excellent intramolecular charge transfer absorption and excited state absorption, showing high nonlinear optical limiting performance and having important applications in laser protection. The preparation method of the electron donor-acceptor type organic conjugated polymer provided in the present invention is simple, and the material structure is easy to modify. Description of the Drawings

[0066] The following further describes in detail the specific embodiments of the present invention with reference to the drawings.

[0067] Figure 1 Shows the infrared spectrum of the nonlinear optical material P1-Pt prepared in Example 1.

[0068] Figure 2 Shows the nonlinear optical property spectra of the nonlinear optical materials P1-Pt and P1 prepared in Example 1 and Comparative Example 1.

[0069] Figure 3 Shows the infrared spectrum of the nonlinear optical material P2-Pt prepared in Example 2.

[0070] Figure 4The infrared spectrum of the nonlinear optical material P2-Pt prepared in Example 3 is shown.

[0071] Figure 5 The infrared spectrum of the nonlinear optical material P1 prepared in Comparative Example 1 is shown.

[0072] Figure 6 The infrared spectrum of the nonlinear optical material P2 prepared in Comparative Example 2 is shown. Detailed implementation manners

[0073] To illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and the accompanying drawings. Similar components in the drawings are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0074] Example 1

[0075] The structural formula of the platinum(II) electron donor-acceptor type organic conjugated polymer in this example is as follows:

[0076]

[0077] The synthesis route of the platinum(II) electron donor-acceptor type organic conjugated polymer P1-Pt is as follows:

[0078]

[0079] The synthesis of the platinum(II) electron donor-acceptor type organic conjugated polymer P1-Pt is as follows:

[0080] Synthesis of monomer M-1: 2,5-Dibromopyridine (11.85 g, 50 mmol), 4-bromophenylboronic acid (10.35 g, 50 mmol), potassium carbonate (17.28 g, 125 mmol) and tetrakis(triphenylphosphine)palladium (0.58 g, 0.5 mmol) were placed in a 200 mL two-necked flask. After purging with nitrogen, tetrahydrofuran (150 mL) and water (50 mL) were added under nitrogen protection. After reacting at 60 °C for 24 h, it was cooled to room temperature, extracted three times with dichloromethane, the organic layers were combined, washed three times with water, and then dried over anhydrous sodium sulfate and the solvent was removed. After column chromatography with dichloromethane / petroleum ether (v / v, 1:5), white solid M-1 (10.45 g, yield 67%) was obtained. 1 HNMR(400MHz,CDCl 3 )δ:8.72(d,1H),7.89(dd,1H),7.85(d,2H),7.60(m,3H).

[0081] Synthesis of monomer M1-Pt: M-1 (0.50 g, 1.60 mmol) and potassium tetrachloroplatinate (0.33 g, 0.8 mmol) were placed in a 25 mL two-necked flask. Under nitrogen protection, 9 mL of 2-ethoxyethanol and 3 mL of water were added. The reaction was carried out at 80 °C for 24 h with stirring. After cooling to room temperature, it was a yellow solid suspension. Filtration was carried out by suction, and the solid was washed three times with water and ethanol in sequence. After drying in vacuo at 60 °C, the intermediate was obtained as a yellow powdery solid (0.65 g, yield 75%). Take the yellow powder (0.65 g, 0.6 mmol) and sodium carbonate (0.25 g, 2.4 mmol) and place them in a 25 mL two-necked flask. Under nitrogen protection, 2,4-pentanedione (0.24 mL, 2.4 mmol) and 6 mL of 2-ethoxyethanol were added. The reaction was stirred at 100 °C for 24 h. After the reaction solution was cooled to room temperature, it was poured into 30 mL of water and extracted with dichloromethane (3×40 mL). After combining the organic phases, they were dried with anhydrous sodium sulfate to obtain a dark brown solution. The solvent was removed by rotary evaporation, and column chromatography separation was carried out with dichloromethane: petroleum ether (v / v, 1:2) to obtain yellow solid M1-Pt (170 mg, yield 23%). 1 H NMR (400 MHz, CDCl 3 ) δ: 9.05 (d, 1H), 7.92 (dd, 1H), 7.67 (d, 1H), 7.43 - 7.41 (d, 1H), 7.24 (s, 2H), 5.49 (s, 1H), 2.04 (s, 6H).

[0082] Synthesis of polymer P1-Pt: M-4T (83 mg, 100 μmol), organoplatinum monomer M1-Pt (61 mg, 100 μmol), tris(o-tolyl)phosphine (5 mg, 16 μmol) and a catalytic amount of methyltrioctylammonium chloride were placed in a Schlenk tube. 5 mL of freshly distilled toluene and 1 mL of 2 M aqueous potassium carbonate solution were added. Finally, the catalyst tris(dibenzylideneacetone)dipalladium (2 mg, 2 μmol) was added. The solution was purged with nitrogen 4 - 5 times during the freeze-thaw cycle and then stirred and heated in an oil bath at 100 °C for 48 h. The reaction was stopped and allowed to return to room temperature. The reaction solution was poured into methanol and stirred for 3 h, and then the solid was obtained by suction filtration. The solid was purified by a Soxhlet extractor, and a small amount of monomer, oligomer and catalyst were removed with methanol, acetone and n-hexane in sequence. The product was then extracted with chloroform and precipitated in methanol. After removing the solvent, it was dried in vacuo for 48 h to obtain the final product, i.e., the platinum(II) electron donor-acceptor type organic conjugated polymer nonlinear optical material P1-Pt (45 mg, yield 36%). The infrared spectrum characterization is as Figure 1 shown, IR (KBr, cm -1)3429, 3061, 2963, 2911, 2858, 2363, 1644, 1574, 1514, 1469, 1378, 1311, 1258, 1183, 1070, 1010, 793。

[0083] The nonlinear optical properties of the platinum(II) electron donor-acceptor type organic conjugated polymer P1-Pt:

[0084] The platinum(II) electron donor-acceptor type organic conjugated polymer P1-Pt was dissolved in 1,1,2,2-tetrachloroethane, placed in a 1-mm quartz cuvette, and its linear transmittance at a wavelength of 532 nm was adjusted to 60%.

[0085] The nonlinear optical properties of the material were tested by the Z-scan technique. The test laser was a Nd:YAG pulsed laser with a pulse width of 4 ns, a pulse frequency of 10 Hz, and a laser wavelength of 532 nm. The laser incident energy was 15 μJ. As Figure 2 shown, the polymer exhibited typical reverse-saturable absorption nonlinear optical properties, and the normalized transmittance decreased to 0.74. Therefore, the platinum(II) electron donor-acceptor type organic conjugated polymer P1-Pt has a laser-limiting effect and can be used for laser protection.

[0086] Example 2

[0087] The structural formula of a platinum(II) electron donor-acceptor type organic conjugated polymer in this example is as follows:

[0088]

[0089] The synthesis route of the platinum(II) electron donor-acceptor type organic conjugated polymer P2-Pt is as follows:

[0090]

[0091] The synthesis of the platinum(II) electron donor-acceptor type organic conjugated polymer P2-Pt is as follows:

[0092] Synthesis of monomer M'-2: 2,5-Dibromopyridine (11.85 g, 50 mmol), thiophene-2-boronic acid (6.40 g, 50 mmol), potassium carbonate (21 g, 150 mmol) and tetrakis(triphenylphosphine)palladium (1.15 g, 1.0 mmol) were placed in a 200 mL two-necked flask. After purging with nitrogen, tetrahydrofuran (100 mL) and water (60 mL) were added under nitrogen protection. After reacting at 60 °C for 24 h, the reaction mixture was cooled to room temperature, extracted three times with dichloromethane, the organic layers were combined, washed three times with water, and then dried over anhydrous sodium sulfate and the solvent was removed. After column chromatography with ethyl acetate / petroleum ether (v / v, 1:30), white solid M'-2 (7.51 g, yield 63%) was obtained. 1 HNMR(400MHz,CDCl 3 )δ:8.62(d,1H),7.81(dd,1H),7.61(dd,1H),7.55(d,1H),7.42(dd,1H),7.12(dd,1H).

[0093] Synthesis of monomer M-2: Compound M'-2 (2 g, 8.33 mmol) was dissolved in 10 mL of N,N-dimethylformamide and cooled to 0 °C in an ice bath. A solution of N-bromosuccinimide (1.48 g, 8.33 mmol) in 5 mL of N,N-dimethylformamide was added dropwise. After the addition was complete, the reaction mixture was allowed to react overnight at room temperature. The reaction mixture was poured into ice water and extracted three times with dichloromethane. The organic phases were combined and washed three times with water, dried over anhydrous sodium sulfate, and then subjected to column chromatography with dichloromethane / petroleum ether (v / v, 1:1) to obtain white solid M-2 (1.56 g, yield 59%). 1 H NMR(400MHz,CDCl 3 )δ:8.58(s,1H),7.80(m,1H),7.46(d,1H),7.32(d,1H),7.06(d,1H).

[0094] Synthesis of organoplatinum monomer M2-Pt: M-2 (0.40 g, 1.25 mmol) and potassium tetrachloroplatinate (0.26 g, 0.63 mmol) were placed in a 25 mL two-necked flask. Under nitrogen protection, 9 mL of 2-ethoxyethanol and 3 mL of water were added. The reaction was carried out at 80 °C for 24 h with stirring. After cooling to room temperature, it was a brown solid suspension. Filtration was carried out by suction, and the solid was washed with water and ethanol three times in sequence. After drying in vacuo at 60 °C, the intermediate was obtained as a yellow powdery solid (0.42 g, yield 69%). Take the yellow powder (1.25 g, 1.14 mmol) and sodium carbonate (0.48 g, 4.56 mmol) and place them in a 25 mL two-necked flask. Under nitrogen protection, 2,4-pentanedione (0.47 mL, 4.56 mmol) and 30 mL of 2-ethoxyethanol were added. The reaction was stirred and carried out at 100 °C for 24 h. After the reaction solution was cooled to room temperature, it was poured into 60 mL of water and extracted with dichloromethane (3 × 40 mL). After combining the organic phases, they were dried with anhydrous sodium sulfate to obtain a dark brown solution. The solvent was removed by rotary evaporation, and column chromatography separation was carried out with dichloromethane: petroleum ether (v / v, 1:1) to obtain a reddish-brown solid M2-Pt (0.27 g, yield 19%). 1 H NMR(400MHz,CDCl 3 )δ:8.82(s,1H),7.78-7.76(s,1H),7.08(s,1H),7.03-7.01(d,1H),5.48(s,1H),2.02(s,6H).

[0095] Synthesis of polymer P2-Pt: M-4T (83 mg, 100 μmol), organoplatinum monomer M2-Pt (61 mg, 100 μmol), tris(o-tolyl)phosphine (5 mg, 16 μmol) and a catalytic amount of methyltrioctylammonium chloride were placed in a Schlenk tube. Then, 5 mL of freshly distilled toluene and 1 mL of 2 M aqueous potassium carbonate solution were added. Finally, the catalyst tris(dibenzylideneacetone)dipalladium (2 mg, 2 μmol) was added. The solution was purged with nitrogen 4 - 5 times during the freeze-thaw cycle and placed in an oil bath at 100 °C and stirred and heated for 48 h. The reaction was stopped and allowed to return to room temperature. The reaction solution was poured into methanol and stirred for 3 h, and then filtration was carried out to obtain a solid. The solid was purified by a Soxhlet extractor, and methanol, acetone, n-hexane and chloroform were used in sequence to remove a small amount of monomers, oligomers and catalysts. The remaining solid was dried in vacuo for 48 h to obtain the final product, i.e., the platinum(II) electron donor-acceptor type organic conjugated polymer nonlinear optical material P2-Pt (109 mg, yield 89%). Its infrared spectrum characterization is as Figure 3 shown, IR(KBr,cm -1 )3429,2948,2911,2858,2625,2370,1626,1514,1409,1213,1153,1003,830,702.

[0096] Nonlinear optical properties of the platinum(II) electron donor-acceptor type organic conjugated polymer P2-Pt:

[0097] Dissolve the platinum(II) electron donor-acceptor type organic conjugated polymer P2-Pt in 1,1,2,2-tetrachloroethane, place it in a 1-mm quartz cuvette, and adjust its linear transmittance at a wavelength of 532 nm to 60%.

[0098] Test the nonlinear optical properties of the material by Z-scan technology. The test laser is a Nd:YAG pulsed laser with a pulse width of 4 ns, a pulse frequency of 10 Hz, and a laser wavelength of 532 nm. The laser incident energy is 15 μJ. This polymer has reverse saturable absorption nonlinear optical properties similar to P1-Pt, and the normalized transmittance drops to 0.65. Therefore, the platinum(II) electron donor-acceptor type organic conjugated polymer P2-Pt has a laser limiting effect and can be used for laser protection.

[0099] Example 3

[0100] The structural formula of a platinum(II) electron donor-acceptor type organic conjugated polymer in this example is as follows:

[0101]

[0102] The synthesis route of the platinum(II) electron donor-acceptor type organic conjugated polymer P3-Pt is as follows:

[0103]

[0104] Synthesis of the platinum(II) electron donor-acceptor type organic conjugated polymer P3-Pt is as follows:

[0105] Synthesis of M'-3: Place 2-bromothiazole (11 g, 65.7 mmol), thiophene-2-boronic acid (8.6 g, 65.7 mmol), potassium carbonate (27.22 g, 197 mmol), and tetrakis(triphenylphosphine)palladium(0) (0.76 g, 0.66 mmol) in a 200-mL two-necked flask. After purging with nitrogen, add tetrahydrofuran (100 mL) and water (50 mL) under nitrogen protection. After reacting at 60 °C for 24 h, cool to room temperature, extract three times with dichloromethane, combine the organic layers, wash three times with water, and then dry over anhydrous sodium sulfate and remove the solvent. After column chromatography with ethyl acetate / petroleum ether (v / v, 1:20), a brown oily liquid M'-3 (2.34 g, yield 21%) is obtained. 1 H NMR(400MHz,CDCl 3)δ: 7.73 (d, 1H), 7.49 (d, 1H), 7.36 (d, 1H), 7.21 (d, 1H), 7.05 (t, 1H).

[0106] Synthesis of monomer M-3: Dissolve M'-3 (2.34 g, 13.9 mmol) in 20 mL of N,N-dimethylformamide, and cool it to 0 °C in an ice bath. Dropwise add a 10 mL N,N-dimethylformamide solution of N-bromosuccinimide (4.93 g, 27.7 mmol). After the addition is complete, allow the reaction to proceed overnight at room temperature. Pour the reaction mixture into ice water and extract it three times with dichloromethane. Combine the organic phases and wash them three times with water. Dry the organic phase over anhydrous sodium sulfate, and then perform column chromatography using dichloromethane / petroleum ether (v / v, 1:1) to obtain white solid M-3 (3.16 g, yield 70%). 1 H NMR (400 MHz, CDCl 3 )δ: 7.60 (s, 1H), 7.16 (d, 1H), 7.02 (d, 1H).

[0107] Synthesis of monomer M3-Pt: Place M-3 (0.50 g, 1.54 mmol) and potassium tetrachloroplatinate (0.32 g, 0.77 mmol) in a 25 mL two-necked flask. Under nitrogen protection, add 9 mL of 2-ethoxyethanol and 3 mL of water. Stir and react at 80 °C for 24 h. After cooling to room temperature, it is a brown solid suspension. Filter by suction, wash the solid three times with water and ethanol in sequence, and dry it in vacuo at 60 °C to obtain an intermediate as a yellow powdery solid (0.48 g, yield 55%). Take the yellow powder (0.22 g, 0.2 mmol) and silver oxide (85 mg, 0.37 mmol) and place them in a 50 mL two-necked flask. Under nitrogen protection, add 2,4-pentanedione (0.08 mL, 0.8 mmol) and 20 mL of tetrahydrofuran. React with stirring at 80 °C for 24 h. After the reaction solution is cooled to room temperature, rotary evaporate to remove the solvent, and perform column chromatography separation using dichloromethane:petroleum ether (v / v, 1:1) to obtain yellow solid M3-Pt (54 mg, yield 22%). 1 H NMR (400 MHz, CDCl 3 )δ: 7.69 (s, 1H), 7.10 (s, 1H), 5.50 (s, 1H), 1.98 (s, 6H).

[0108] Synthesis of Polymer P3-Pt: M-4T (83 mg, 100 μmol), organoplatinum monomer M3-Pt (63 mg, 100 μmol), tris(o-tolyl)phosphine (5 mg, 16 μmol), and a catalytic amount of methyltrioctylammonium chloride were placed in a Schlenk tube. Then, 5 mL of freshly distilled toluene and 1 mL of 2 M aqueous potassium carbonate solution were added. Finally, the catalyst tris(dibenzylideneacetone)dipalladium (2 mg, 2 μmol) was added. The solution was purged with nitrogen 4 - 5 times during freeze-thaw cycles and then stirred and heated in an oil bath at 100 °C for 48 h. The reaction was stopped and allowed to return to room temperature. The reaction mixture was poured into methanol and stirred for 3 h, and then the solid was obtained by filtration. The solid was purified using a Soxhlet extractor, and small amounts of monomers, oligomers, and catalysts were removed successively with methanol, acetone, and n-hexane. The product was then extracted with chloroform and precipitated in methanol. After removing the solvent, it was dried under vacuum for 48 h to obtain the final product, i.e., the platinum(II) electron donor-acceptor type organic conjugated polymer nonlinear optical material P3-Pt (45 mg, yield 36%). Its infrared spectrum characterization is as Figure 4 shown, IR (KBr, cm -1 ) 3429, 3068, 2926, 2851, 2363, 1641, 1574, 1506, 1431, 1251, 1161, 1093, 1018, 957, 800, 710, 650.

[0109] Nonlinear Optical Properties of Platinum(II) Electron Donor-Acceptor Type Organic Conjugated Polymer P3-Pt:

[0110] The platinum(II) electron donor-acceptor type organic conjugated polymer P3-Pt was dissolved in 1,1,2,2-tetrachloroethane, placed in a 1-mm quartz cuvette, and its linear transmittance at a wavelength of 532 nm was adjusted to 60%.

[0111] The nonlinear optical properties of the material were tested by the Z-scan technique. The test laser was a Nd:YAG pulsed laser with a pulse width of 4 ns, a pulse frequency of 10 Hz, and a laser wavelength of 532 nm. The laser incident energy was 15 μJ. This polymer exhibited reverse saturable absorption nonlinear optical properties similar to those of P1-Pt, and the normalized transmittance decreased to 0.73. Therefore, the platinum(II) electron donor-acceptor type organic conjugated polymer P3-Pt has a laser limiting effect and can be used for laser protection.

[0112] Comparative Example 1

[0113] The structural formula of the platinum(II) electron donor-acceptor type organic conjugated polymer P1 not contained in this comparative example is as follows:

[0114]

[0115] The synthetic route of the platinum(II)-free electron donor-acceptor type organic conjugated polymer P1 is as follows:

[0116]

[0117] The synthesis of the platinum(II)-free electron donor-acceptor type organic conjugated polymer P1 is as follows:

[0118] Synthesis of monomer M-1: 2,5-Dibromopyridine (11.85 g, 50 mmol), 4-bromophenylboronic acid (10.35 g, 50 mmol), potassium carbonate (17.28 g, 125 mmol) and tetrakis(triphenylphosphine)palladium(0) (0.58 g, 0.5 mmol) were placed in a 200 mL two-necked flask. After purging with nitrogen, tetrahydrofuran (150 mL) and water (50 mL) were added under nitrogen protection. After reacting at 60 °C for 24 h, the reaction mixture was cooled to room temperature, extracted three times with dichloromethane, the organic layers were combined, washed three times with water, and then dried over anhydrous sodium sulfate and the solvent was removed. After column chromatography on dichloromethane / petroleum ether (v / v, 1:5), white solid M-1 (10.45 g, yield 67%) was obtained. 1 HNMR(400MHz,CDCl 3 )δ:8.72(d,1H),7.89(dd,1H),7.85(d,2H),7.60(m,3H).

[0119] Synthesis of polymer P1: Benzodithiophene derivative M-4T (83 mg, 100 μmol), monomer A-2 (32 mg, 100 μmol), tris(o-tolyl)phosphine (5 mg, 16 μmol) and a catalytic amount of methyltrioctylammonium chloride were placed in a Schlenk tube. Then, 5 mL of freshly distilled toluene and 1 mL of 2 M aqueous potassium carbonate solution were added. Finally, catalyst tris(dibenzylideneacetone)dipalladium(0) (2 mg, 2 μmol) was added. The solution was purged with nitrogen 4 - 5 times during freeze-thaw cycles, placed in an oil bath at 100 °C and stirred and heated for 48 h. The reaction was stopped and allowed to return to room temperature. The reaction mixture was poured into methanol and stirred for 3 h, and then filtered to obtain a solid. The solid was purified by Soxhlet extraction, and methanol, acetone, n-hexane and chloroform were used in turn to remove a small amount of monomers, oligomers and catalysts. The remaining solid was dried in vacuo for 48 h to obtain product P1 (87 mg, yield 92%). The infrared spectrum characterization is as Figure 5 shown, IR(KBr,cm -1 )3430,2949,2919,2844,2371,1635,1575,1462,1365,1155,1019,809,629.

[0120] The nonlinear optical properties of the platinum(II)-free electron donor-acceptor type organic conjugated polymer P1:

[0121] The platinum(II)-free electron donor-acceptor type organic conjugated polymer P1 was dissolved in 1,1,2,2-tetrachloroethane, placed in a 1-mm quartz cuvette, and its linear transmittance at a wavelength of 532 nm was adjusted to 60%.

[0122] The nonlinear optical properties of the material were tested by the Z-scan technique. The test laser was a Nd:YAG pulsed laser with a pulse width of 4 ns, a pulse frequency of 10 Hz, and a laser wavelength of 532 nm. The incident laser energy was 15 μJ. As Figure 2 shown, this polymer exhibited typical reverse saturable absorption nonlinear optical properties, and the normalized transmittance decreased to 0.80. However, compared with the polymer P1-Pt containing platinum(II) in the conjugated backbone, the platinum(II)-free polymer showed weak nonlinear optical properties.

[0123] Comparative Example 2

[0124] The structural formula of the platinum(II)-free electron donor-acceptor type organic conjugated polymer in this comparative example is as follows:

[0125]

[0126] The synthesis route of the platinum(II)-free electron donor-acceptor type organic conjugated polymer P2 is as follows:

[0127]

[0128] The synthesis of the platinum(II)-free electron donor-acceptor type organic conjugated polymer P2 is as follows:

[0129] Synthesis of M'-3: 2-Bromothiazole (11 g, 65.7 mmol), thiophene-2-boronic acid (8.6 g, 65.7 mmol), potassium carbonate (27.22 g, 197 mmol), and tetrakis(triphenylphosphine)palladium (0.76 g, 0.66 mmol) were placed in a 200-mL two-necked flask. After purging with nitrogen, tetrahydrofuran (100 mL) and water (50 mL) were added under nitrogen protection. After reacting at 60 °C for 24 h, it was cooled to room temperature, extracted three times with dichloromethane, the organic layers were combined, washed three times with water, and then dried over anhydrous sodium sulfate and the solvent was removed. After column chromatography with ethyl acetate / petroleum ether (v / v, 1:20), a brown oily liquid M'-3 (2.34 g, yield 21%) was obtained. 1 H NMR (400 MHz, CDCl 3 ) δ: 7.73 (d, 1H), 7.49 (d, 1H), 7.36 (d, 1H), 7.21 (d, 1H), 7.05 (t, 1H).

[0130] Synthesis of monomer M-3: Dissolve M'-3 (2.34 g, 13.9 mmol) in 20 mL of N,N-dimethylformamide, and cool it to 0 °C in an ice bath. Dropwise add a 10 mL N,N-dimethylformamide solution of N-bromosuccinimide (4.93 g, 27.7 mmol). After the addition is complete, allow the reaction to proceed overnight at room temperature. Pour the reaction mixture into ice water and extract it three times with dichloromethane. Combine the organic phases and wash them three times with water. After drying the organic phase with anhydrous sodium sulfate, perform column chromatography using dichloromethane / petroleum ether (v / v, 1:1) to obtain white solid M-3 (3.16 g, yield 70%). 1 H NMR (400 MHz, CDCl 3 ) δ: 7.60 (s, 1H), 7.16 (d, 1H), 7.02 (d, 1H).

[0131] Synthesis of polymer P2: Place benzodithiophene derivative M-4T (83 mg, 100 μmol), monomer A-1 (33 mg, 100 μmol), tris(o-tolyl)phosphine (5 mg, 16 μmol), and a catalytic amount of methyltrioctylammonium chloride in a Schlenk tube. Then, add 5 mL of freshly distilled toluene and 1 mL of 2 M aqueous potassium carbonate solution. Finally, add the catalyst tris(dibenzylideneacetone)dipalladium (2 mg, 2 μmol). Replace the nitrogen in the solution 4 - 5 times during the freeze-thaw cycle, and stir and heat it in an oil bath at 100 °C for 48 h. Stop the reaction and allow it to return to room temperature. Pour the reaction mixture into methanol and stir for 3 h, then filter to obtain a solid. Purify the solid using a Soxhlet extractor, successively removing small amounts of monomers, oligomers, and catalysts with methanol, acetone, and n-hexane. Then extract the product with chloroform and precipitate it in methanol. After removing the solvent, dry it under vacuum for 48 h to obtain product P2 (23 mg, yield 24%). The infrared spectrum characterization is as follows Figure 6 shown, IR (KBr, cm -1 ) 3429, 3061, 2918, 2858, 2354, 1649, 1544, 1446, 1363, 1303, 1228, 1145, 1063, 1018, 785, 620.

[0132] The nonlinear optical properties of the platinum(II)-free electron donor-acceptor type organic conjugated polymer P2

[0133] Dissolve the platinum(II)-free electron donor-acceptor type organic conjugated polymer P2 in 1,1,2,2-tetrachloroethane, place it in a 1 mm quartz cuvette, and adjust its linear transmittance at a wavelength of 532 nm to 60%.

[0134] The nonlinear optical properties of the material were tested by Z-scan technique. The test laser was a Nd:YAG pulsed laser with a pulse width of 4 ns, a pulse frequency of 10 Hz, and a laser wavelength of 532 nm. The incident laser energy was 15 μJ. This polymer exhibited reverse saturable absorption nonlinear optical properties, and the normalized transmittance decreased to 0.79. However, compared with the polymer P3-Pt containing platinum(II) on the conjugated backbone, the polymer without platinum(II) showed weak nonlinear optical properties.

[0135] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. Application of a nonlinear optical material in laser limiting, characterized in that, the nonlinear optical material is prepared from an electron donor-acceptor type organic conjugate polymer, and the structural formula of the polymer is shown as follows: , or ; wherein, n is selected from positive integers of 1-10.

2. The application according to claim 1, characterized in that, in the application, the laser used is a pulsed laser; the pulse width of the pulsed laser is 4-8 ns, the pulse frequency is 10 Hz, and the wavelength is 532 nm.

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