CN104151533B - A kind of fluorescent conjugated polymer containing phenothiazine group and synthetic method thereof and application - Google Patents

Abstract

The invention belongs to the field of conjugated polymers, and discloses a fluorescent conjugated polymer containing phenothiazine groups, a synthesis method and an application thereof. The synthesis method is to first synthesize N-alkyl-3,6-bis(ethynyl) phenothiazine monomers, and then combine N-alkyl-3,6-bis(ethynyl) phenothiazine monomers with N ‑octyl‑3,6‑bis(ethynyl)carbazole monomer or 4,7‑diethynyl‑2,1,3‑benzothiaxazole monomer is completely dissolved in o-dichlorobenzene Stirring reaction in the catalytic system of CuCl and TMEDA; after the reaction, precipitate and filter in the mixed solution of methanol and concentrated hydrochloric acid, and dry in vacuum to obtain a fluorescent conjugated polymer containing phenothiazine groups. The present invention improves the solubility of the polymer by introducing an alkyl chain on the phenothiazine group; by introducing groups with different push and pull electronic effects, changing the structure, and providing a polymer with excellent photoelectric properties, solubility and Thermally stable conjugated polymers.

Description

A kind of fluorescent conjugated polymer containing phenothiazine group and its synthesis method and application

technical field

The invention belongs to the field of conjugated polymers, and in particular relates to a fluorescent conjugated polymer containing phenothiazine groups, a synthesis method and application thereof.

Background technique

Conjugated polymers are a new type of functional material. Because they have the photoelectric properties of metal semiconductors, are easy to process, and have certain flexibility, they are widely used in the fields of solar cells, photoelectric conversion, and optical information materials. . Fluorescent conjugated polymers have strong fluorescence quantum yield and molar extinction coefficient due to their unique π-π* molecular wire structure. Compared with traditional small-molecule fluorescent materials, it has the advantages of adjustable structure, high sensitivity, direct spin-coating, and good stability, so it has attracted more and more attention.

In 1869, Carl Glaser successfully synthesized 1,4-diphenyl-1,3-butadiyne using phenylacetylene as a raw material, cuprous chloride as a catalyst, and ammonia and ethanol as solvents in an air atmosphere. However, the obtained phenyl copper acetylide intermediate is unstable and easily explodes under dry conditions, which makes post-processing very difficult and difficult to obtain practical application. Until 1962, the American chemist Hay added tetramethylethylenediamine as the ligand of the copper catalyst to the system, and successfully synthesized diacetylenic compounds under the condition of feeding oxygen with o-dichlorobenzene or acetone as the solvent. The improved reaction conditions are mild and the yields are high, but the resulting polymers are mostly insoluble and infusible, making them difficult to test and process. In 1998, Kijima et al. improved the raw material by introducing a long alkoxy chain at the para-position of 1,4-diethynylbenzene, so that it has good solubility in both chloroform and tetrahydrofuran.

The phenothiazine molecule contains two heteroatoms of nitrogen and sulfur, which is an electron-rich structure, and its lone pair of electrons is easy to form a delocalized structure with the benzene ring, which has good fluorescence, strong electron donating ability and hole transport performance. In addition, the phenothiazine molecule has a butterfly-like symmetrical non-planar structure, which can effectively prevent the accumulation of π bonds and the formation of interchain excimer compounds, thereby improving the fluorescence quantum efficiency of the polymer.

Contents of the invention

In order to overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide a fluorescent conjugated polymer containing phenothiazine groups with excellent luminescent properties, good solubility and thermal stability;

Another object of the present invention is to provide a method for synthesizing the above-mentioned fluorescent conjugated polymer containing phenothiazine groups;

Another object of the present invention is to provide the application of the above-mentioned fluorescent conjugated polymers containing phenothiazine groups.

The object of the present invention is achieved through the following technical solutions:

A fluorescent conjugated polymer containing a phenothiazine group, its structural formula is:

Wherein, x is a natural number ranging from 2 to 100, and y is a natural number ranging from 2 to 200;

R ₁ is an alkyl group with 1 to 18 carbons;

R ₂ is N-octylcarbazole or benzothiaxazole;

The structural formula of the N-octylcarbazole is

The structural formula of the benzothiaxazole is

The above-mentioned synthetic method of the fluorescent conjugated polymer containing phenothiazine group comprises the following steps:

(1) Synthesis of N-alkyl-3,6-bis(ethynyl)phenothiazine monomer: 3,6-dibromo-N-alkylphenothiazine and divalent palladium catalyst are added to the reactor , add cuprous iodide (CuI), under the protection of nitrogen, then add toluene, triethylamine and 3,3'-dimethyl-3-hydroxypropyne, heat up the reaction, filter the reaction product, and use anhydrous Wash with ether, remove the solvent by distillation under normal pressure, and purify with column chromatography to obtain the intermediate;

Under nitrogen protection, the intermediate and NaOH were heated and refluxed in toluene solvent, the toluene solvent was distilled off under reduced pressure, and purified by column chromatography to obtain N-alkyl-3,6-bis(ethynyl)phenothiazine mono body;

(2) Synthesis of fluorescent conjugated polymers containing phenothiazine groups: N-alkyl-3,6-bis(ethynyl) phenothiazine monomers obtained in step (1) and N-octyl-3 , 6-bis(ethynyl)carbazole monomer or 4,7-diethynyl-2,1,3-benzothiaxazole monomer was dissolved in o-dichlorobenzene, stirred until completely dissolved to obtain a mixed solution Then the resulting mixed solution is transferred to the catalytic system containing cuprous chloride (CuCl) and tetramethylethylenediamine (TMEDA), and under the condition of feeding air, the reaction is stirred; after the reaction finishes, the reaction solution is poured into a mixed solution of methanol and concentrated hydrochloric acid for precipitation, filtered, and vacuum-dried the filtered solid to obtain the fluorescent conjugated polymer containing phenothiazine groups.

In the preparation method of the above-mentioned fluorescent conjugated polymer containing phenothiazine groups:

Preferably, the alkyl carbon number of the 3,6-dibromo-N-alkylphenothiazine in step (1) is 1-18;

Preferably, the molar ratio of the 3,6-dibromo-N-alkylphenothiazine to the divalent palladium catalyst in step (1) is 1: (0.02-0.05);

Preferably, the molar ratio of 3,6-dibromo-N-alkylphenothiazine to cuprous iodide in step (1) is 1:(0.001～0.005);

Preferably, in step (1), in terms of mole fractions, 6-15 mL of toluene and 6-15 mL of triethylamine are added to every mmol of 3,6-dibromo-N-alkylphenothiazine, 3,3' -Dimethyl-3-hydroxypropyne 0.3~1.5mL;

Preferably, the temperature of the heating reaction in step (1) is 80-120° C., and the reaction time is 10-24 hours;

Preferably, the molar ratio of the intermediate in step (1) to NaOH is 1: (1-2);

Preferably, the temperature of the temperature-rising reflux reaction in step (1) is 80-120° C., and the reaction time is 3-10 h;

Preferably, the N-alkyl-3,6-bis(ethynyl)phenothiazine monomer and N-octyl-3,6-bis(ethynyl)carbazole monomer or 4, The molar ratio of 7-diethynyl-2,1,3-benzothiaxazole monomer is 1:(1～3);

Preferably, the temperature for stirring until completely dissolved in step (2) is 20-60°C; preferably, the stirring reaction time for step (2) is 4-60 minutes;

Preferably, the catalytic system containing cuprous chloride and tetramethylethylenediamine described in step (2) uses 20-30 mg of cuprous chloride and 0.06-30 mg of tetramethylethylenediamine for each millimole of diacetylenic monomer. 0.08mL and o-dichlorobenzene 20-50mL preparation;

Preferably, the mixed solution of methanol and concentrated hydrochloric acid described in step (2) is prepared by mixing 50-100 mL of methanol and 0.1-0.3 mL of concentrated hydrochloric acid per millimole of diacetylenic monomer;

The diacetylene monomer is N-alkyl-3,6-bis(ethynyl)phenothiazine monomer and N-octyl-3,6-bis(ethynyl)carbazole monomer or 4,7- The sum of diethynyl-2,1,3-benzothiaxazole monomers.

Application of the fluorescent conjugated polymer containing phenothiazine groups in the fields of organic light-emitting devices, solar cells and fluorescent sensors.

The present invention synthesizes a fluorescent conjugated polymer containing a phenothiazine group by optimizing the reaction conditions, adjusting the reaction temperature, time, monomer ratio, etc., and the fluorescent conjugated polymer containing a phenothiazine group has good Excellent solubility and thermal stability, the decomposition temperature is between 373°C and 426°C, and the residual carbon content is above 60% at 800°C; in addition, the fluorescent conjugated polymer containing phenothiazine groups also has excellent photoelectric properties , the HOMO energy level is around -5.60eV, which is a good hole transport material.

Compared with the prior art, the present invention has the following advantages and effects: the phenothiazine group-containing fluorescent conjugated polymer of the present invention introduces an alkyl chain on the phenothiazine group, which can improve solubility for characterization testing and processing application; the synthesis method of the present invention, through molecular design, introduces groups with push and pull electron effects into the conjugated system, and synthesizes a fluorescent conjugated polymer with novel structure, excellent optical properties and electrochemical properties The fluorescent conjugated polymer containing phenothiazine group of the present invention has a good application prospect in the fields of organic light-emitting devices, solar cells and fluorescent sensors.

Description of drawings

Figure 1 shows the fluorescence conjugate polymerization of N-octyl-3,6-bis(ethynyl)phenothiazine, N-octyl-3,6-bis(ethynyl)carbazole and the obtained phenothiazine-containing groups The nuclear magnetic resonance figure of object P3;

Figure 2 N-octyl-3,6-bis(ethynyl)phenothiazine, 4,7-diethynyl-2,1,3-benzothiaxazole and the resulting phenothiazine-containing group fluorescent co- NMR image of conjugated polymer P7.

detailed description

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Embodiment 1, the synthesis of N-octyl-3,6-two (ethynyl) phenothiazines:

Add 2g of 3,6-dibromo-N-octylphenothiazine (4.26mmol), 2mg of CuI, and 60mg of Pd(Ph ₃ P) ₂ Cl ₂ into a 100ml (19#) two-necked flask, Under the protection of nitrogen, add 30ml of toluene, 30ml of triethylamine and 1.25ml of 3,3'-dimethyl-3-hydroxypropyne, heat to 110°C, react for 12h; filter the reaction product, and wash with anhydrous ether , evaporate the solvent to dryness, and purify by column chromatography. The developing solvent is a mixed solvent of petroleum ether and ethyl acetate. The volume ratio of petroleum ether and ethyl acetate is 3:1. Purification gives 1.384g of a yellow solid with a yield of 68%. ;

Take 0.35g of the yellow solid (0.73mmol) obtained in the above steps and 30mg of NaOH (0.73mmol) into a 100ml (19#) two-neck flask, under the protection of nitrogen, add 15ml of toluene, heat to 110°C to condense and reflux, and react 4h; the reaction mixture was filtered, washed with toluene, spin-dried the solvent, and purified by column chromatography. The developer was a mixed solvent of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether and ethyl acetate was 5:1. Purified to obtain Yellow viscous liquid 0.159g, yield 60.7%.

The resulting yellow viscous liquid product was detected and analyzed by a Bruker Vector33 infrared spectrometer and a Bruker AV-300 nuclear magnetic resonance instrument, and the results were as follows: IR(KBr),v(cm ^-1 ):3291(≡CH stretching),2925, 2851 (CH stretching), 2104 (C≡C stretching). ¹ H NMR (500MHz, CDCl ₃ ).δ(ppm):7.26,7.20,6.70(6H,Ph),3.81(2H,NCH ₂ ),3.05(2H,≡CH),1.76,1.25-1.38(12H, _CH2 ), 0.86 (3H, _CH3 ).

It can be seen from the infrared data that the resulting yellow viscous liquid product has absorption peaks at 3291cm ^-1 and 2104cm ^-1 , which is consistent with the terminal Alkyne hydrogen (≡C—H) corresponds to the stretching vibration peak of the carbon-carbon triple bond (C≡C); through H ¹ -NMR analysis, the product has a resonance peak at a chemical shift of 3.05ppm, which is the peak of the terminal alkyne hydrogen Resonance peaks, and resonance peaks at other chemical shifts are also assigned clearly. The nuclear magnetic resonance image of the product is shown in A in Fig. 1 .

It can be confirmed that the resulting yellow viscous liquid product has the following structure:

For N-octyl-3,6-bis(ethynyl)phenothiazine.

Embodiment 2, the synthesis of N-octyl-3,6-two (ethynyl) carbazoles:

Add 1g of 3,6-diiodo-N-octylcarbazole (1.9mmol), 1mg of CuI (0.005mmol), and 30mg of Pd(Ph ₃ P) ₂ Cl ₂ to a 100ml (19#) single port circle In the bottom flask, under N ₂ atmosphere, add 15ml of triethylamine, then add 0.6ml of 3,3'-dimethyl-3-hydroxypropyne, and stir at room temperature for 16h; after the reaction stops, the reaction mixture Filter and wash with anhydrous diethyl ether; remove the solvent by distillation under normal pressure, and perform column chromatography purification. The developer uses a mixed solvent of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether and ethyl acetate is 3:1. Yellow solid 0.706g, yield 84.5%;

Take 0.5g of the light yellow solid (1.18mmol) obtained in the above steps and 0.047g of NaOH (1.18mmol) into a 100ml (19#) two-necked round bottom flask, add 15ml of toluene under nitrogen protection, and heat to 110°C Condensate and reflux, react for 3 hours; after stopping the reaction, filter the product, wash with toluene, distill off the solvent under reduced pressure, and purify with column chromatography. The volume ratio was 2:1, and 0.33 g of pale yellow crystals was obtained with a yield of 85.3%.

The obtained pale yellow crystal product was detected and analyzed by Bruker Vector33 infrared spectrometer and Bruker AV-300 nuclear magnetic resonance instrument, the results are as follows: IR(KBr), v(cm ^-1 ): 3296(≡CH stretching), 2925,2854 (CH stretching), 2104 (C≡C stretching). ¹ H NMR (500MHz, CDCl ₃ ).δ(ppm):8.24,7.64,7.61(6H,Ph),4.31(2H,NCH ₂ ),3.10(2H,≡CH),1.91,1.25-1.33(12H, CH ₂ ), 0.88 (3H, CH ₃ ).

It can be seen from the infrared data that the resulting light yellow crystal product has absorption peaks at 3296cm ^-1 and 2104cm ^-1 , which is consistent with the terminal alkyne hydrogen in the N-octyl-3,6-bis(ethynyl)carbazole monomer (≡C—H) corresponds to the stretching vibration peak of the carbon-carbon triple bond (C≡C); through H ¹ -NMR analysis, the product has a resonance peak at the chemical shift of 3.10ppm, which is the resonance peak of the terminal alkyne hydrogen , and the resonance peaks at other chemical shifts are also assigned clearly. The product NMR figure is as shown in B in Figure 1;

It can be confirmed that the resulting pale yellow crystal product has the following structure:

For N-octyl-3,6-bis(ethynyl)carbazole.

Embodiment 3, the synthesis of 4,7-diethynyl-2,1,3-benzothiaxazole:

Add 1g of 4,7-dibromobenzothiaxazole (3.4mmol), a small amount of CuI and 48mg of Pd(Ph ₃ P) ₂ Cl ₂ (0.068mmol) into a 100ml (19#) two-necked round bottom flask in sequence , under N ₂ atmosphere, add 15ml of toluene, 15ml of triethylamine and 1ml of 3,3'-dimethyl-3-hydroxypropyne, raise the temperature to 110°C, condense and reflux, and react for 16h; after the reaction stops, the reaction The mixture was filtered and washed with anhydrous ether; the solvent was distilled off under normal pressure, and purified by column chromatography. The developer was a mixed solvent of petroleum ether and ethyl acetate, and the volume ratio of petroleum ether and ethyl acetate was 2:1. Light yellow solid 0.761g, yield 74.6%;

Take 0.5 g of the light yellow solid (1.67 mmol) obtained in the above steps and 0.067 g of NaOH (1.67 mmol) into a 100 ml (19#) two-necked round-bottomed flask, add 17 ml of toluene under nitrogen protection, and heat to 110 Condensate and reflux at ℃, react for 1 h; after stopping the reaction, filter the product, wash with toluene, distill off the solvent under reduced pressure, and purify by column chromatography. The developer uses a mixed solvent of petroleum ether and dichloromethane, petroleum ether and dichloromethane The volume ratio was 2:1, and 0.175 g of brown needle-like crystals was obtained, with a yield of 55.7%.

The resulting brown needle-like crystal product was detected and analyzed by a Bruker Vector33 infrared spectrometer and a Bruker AV-300 nuclear magnetic resonance instrument, and the results were as follows: IR(KBr),v(cm ^-1 ):3295(≡CH stretching),3052, 2107 (C≡C stretching). ¹ H NMR (300 MHz, CDCl ₃ ), δ (ppm): 7.76 (s, 2H), 3.69 (s, 2H).

It can be seen from the infrared data that the resulting brown needle-like crystal product has absorption peaks at 3295cm ^-1 and 2107cm ^-1 , which is similar to that in 4,7-diethynyl-2,1,3-benzothiaxazole monomer The terminal alkyne hydrogen (≡C—H) corresponds to the stretching vibration peak of the carbon-carbon triple bond (C≡C); through H ¹ -NMR analysis, the product has a resonance peak at the chemical shift of 3.69ppm, which is the terminal alkyne The resonant peak of hydrogen and the resonant peaks at other chemical shifts are also clearly assigned, as shown in B in Figure 2.

It can be confirmed that the obtained brown needle-like crystal has the following structure:

For 4,7-diethynyl-2,1,3-benzothiaxazole.

Example 4

A fluorescent conjugated polymer containing a phenothiazine group, the preparation method of which is as follows:

Get the N-octyl-3,6-bis(ethynyl) phenothiazine of 53.8mg embodiment 1 gain and the N-octyl-3,6-bis(ethynyl) carbazole of 50mg embodiment 2 gain and put into In reaction tube No. 1, dissolve with 1.5ml o-dichlorobenzene; put 2mg cuprous chloride and 0.006ml TMEDA into reaction tube No. 2, dissolve with 2ml o-dichlorobenzene, heat to 50°C and stir for 15min; then Add the solution in No. 1 reaction tube to No. 2 reaction tube, and react for 40 minutes under the condition of passing air; after the reaction stops, pour the reaction solution into a mixture of 50 ml methanol and 0.1 ml concentrated hydrochloric acid to precipitate, filter, Washed with methanol and dried in vacuo to obtain 58 mg of a yellow powdery solid with a yield of 56.4%.

The obtained yellow powdery solid is detected and analyzed by a Bruker Vector33 infrared spectrometer and a Bruker AV-300 nuclear magnetic resonance instrument, and the results are as follows:

IR (KBr), v (cm ^-1 ): 3300 (≡CH stretching), 2208, 2137 (C≡CC≡C stretching), 2107 (C≡C stretching). ¹ H NMR (300MHz, CDCl ₃ ), δ(ppm): 8.24-6.75(Ar-H), 4.31, 3.81(NCH ₂ ), 3.10(≡CH), 3.05(≡CH), 1.86-1.25(CH ₂ ), 0.87 (CH ₃ ).

From the infrared data, it can be seen that the obtained yellow powder solid has stretching vibration peaks of terminal alkyne hydrogen (≡CH) and carbon-carbon triple bond (C≡C) at 3300cm ^-1 and 2107cm ^-1 respectively, and at the wavelength of 2137cm There are two absorption peaks at ^-1 and 2208cm ^-1 , which are the stretching vibration peaks of diacetylene (C≡CC≡C); it can be seen that the product has two peaks at 3.10ppm and 3.05ppm from the nuclear magnetic spectrum. A resonance peak indicates that the product contains carbazole and phenothiazine unit structures, and also contains carbazole and phenothiazine unit unreacted terminal alkyne hydrogens at the end of the molecular chain, as shown in C in Figure 1 for details. The above analysis can show that N-octyl-3,6-bis(ethynyl)phenothiazine monomer and N-octyl-3,6-bis(ethynyl)carbazole monomer have undergone a polymerization reaction to form a copolymer object, its structure is as follows:

where x:y=1:1. Therefore, the obtained yellow powdery solid is the fluorescent conjugated polymer containing phenothiazine groups, which is denoted as polymer P3.

Example 5

A fluorescent conjugated polymer containing a phenothiazine group, the preparation method of which is as follows:

Get the N-octyl-3,6-bis(ethynyl) phenothiazine that 17.9mg embodiment 1 gains and the N-octyl-3,6-bis(ethynyl) carbazole that 49.0mg embodiment 2 gains Put into No. 1 reaction tube, dissolve with 1.5ml o-dichlorobenzene; put 2mg cuprous chloride and 0.006ml TMEDA into No. 2 reaction tube, dissolve with 2ml o-dichlorobenzene, heat to 50°C and stir for 15min; Then add the solution in No. 1 reaction tube to No. 2 reaction tube, and react for 40 minutes under the condition of feeding air; after the reaction stops, pour the reaction solution into a mixture of 50ml methanol and 0.1ml concentrated hydrochloric acid to precipitate, filter , washed with methanol, and dried in vacuo to obtain 44 mg of a yellow powdery solid, which is the fluorescent conjugated polymer containing phenothiazine groups, with a yield of 65.7%. Denoted as polymer P4.

Polymers P1, P2, P5 and polymers P3, P4 are the same series of fluorescent conjugated polymers containing phenothiazine groups, with similar structures and consistent performance; the polymerization method is basically the same, the difference is that N-octyl-3, The amounts of 6-bis(ethynyl)phenothiazine and N-octyl-3,6-bis(ethynyl)carbazole were different. N-octyl-3,6-bis(ethynyl) phenothiazine and N-octyl-3,6-bis(ethynyl)carbazole molar ratio in the polymer P1, P2 and P5 are shown in Table 1 Show.

Example 6

A fluorescent conjugated polymer containing a phenothiazine group, the preparation method of which is as follows:

Take 36mg of N-octyl-3,6-bis(ethynyl)phenothiazine obtained in Example 1 and 18.4mg of 4,7-diethynyl-2,1,3-benzothiazine obtained in Example 3 Put azole into reaction tube No. 1, dissolve with 1.5ml o-dichlorobenzene; put 2mg cuprous chloride and 0.006ml TMEDA into reaction tube No. 2, dissolve with 2ml o-dichlorobenzene, heat to 50°C and stir for 15min Then the solution in the No. 1 reaction tube is added in the No. 2 reaction tube, and reacted under the condition of feeding air for 40min; after the reaction stopped, the reaction solution was poured into the mixed solution of 50ml methanol and 0.1ml concentrated hydrochloric acid to precipitate, It was filtered, washed with methanol, and dried in vacuo to obtain 30 mg of a brown powdery solid with a yield of 55.1%.

Gained brown powdery solid is analyzed by Bruker Vector33 type infrared spectrometer and Bruker AV-300 type nuclear magnetic resonance instrument, and its data are as follows:

IR (KBr), v (cm-1): 3288 (≡CH stretching), 2205, 2140 (C≡CC≡C stretching), 2107 (C≡C stretching). ¹ H NMR (300 MHz, CDCl ₃ ), δ (ppm): 7.76-6.75 (Ar-H), 3.81 (NCH ₂ ), 3.05 (≡CH), 1.78-1.25 (CH ₂ ), 0.87 (CH ₃ ).

From the infrared data, it can be seen that the resulting brown powdery solid has stretching vibration peaks of terminal alkyne hydrogen (≡CH) and carbon-carbon triple bond (C≡C) at 3288cm ^-1 and 2107cm ^-1 respectively, and at a wavelength of 2205cm There are two absorption peaks at ^-1 and 2140cm ^-1 , which are the stretching vibration peaks of diacetylene (C≡CC≡C); from the nuclear magnetic spectrum, it can be seen that the product has two peaks at 3.81ppm and 3.05ppm. A resonance peak indicates that the product contains benzothiaxazole and phenothiazine unit structures, and also contains benzothiaxazole and phenothiazine unit unreacted terminal alkyne hydrogens at the end of the molecular chain, as shown in Figure 2. C shown. The above analysis can show that N-octyl-3,6-bis(ethynyl)phenothiazine monomer and 4,7-diethynyl-2,1,3-benzothiaxazole monomer have undergone a polymerization reaction, A copolymer was produced with the following structure:

where x:y=1:1. Therefore, the obtained brown powdery solid is the fluorescent conjugated polymer containing phenothiazine groups, which is denoted as polymer P7.

Example 7

A fluorescent conjugated polymer containing a phenothiazine group, the preparation method of which is as follows:

Take 26.1 mg of N-octyl-3,6-bis(ethynyl)phenothiazine obtained in Example 1 and 4,7-diethynyl-2,1,3-benzothiazine obtained in Example 3 Put oxazole into reaction tube No. 1, dissolve it with 1.5ml o-dichlorobenzene; put 2 mg cuprous chloride and 0.006 ml TMEDA into reaction tube No. 2, dissolve it with 2 ml o-dichlorobenzene, and heat to 50°C and stir 15min; then add the solution in No. 1 reaction tube to No. 2 reaction tube, and react for 40 min under the condition of feeding air; after the reaction stops, pour the reaction solution into a mixture of 50ml methanol and 0.1ml concentrated hydrochloric acid to precipitate , filtered, washed with methanol, and dried in vacuo to obtain 30 mg of a brown powdery solid, which is the fluorescent conjugated polymer containing phenothiazine groups, with a yield of 60.4%. Denoted as polymer P8.

Polymer P6 and polymers P7 and P8 are the same series of fluorescent conjugated polymers containing phenothiazine groups, with similar structures and consistent performance; the polymerization method is basically the same, the difference is that N-octyl-3,6-bis( Ethynyl)phenothiazine and 4,7-diethynyl-2,1,3-benzothiaxazole were used in different amounts. The molar ratios of N-octyl-3,6-bis(ethynyl)phenothiazine and 4,7-diethynyl-2,1,3-benzothiaxazole in polymer P6 are shown in Table 1 .

Polymer performance testing and analysis:

1. Molecular weight and distribution of fluorescent conjugated polymers containing phenothiazine groups:

The fluorescent conjugated polymers containing phenothiazine groups were prepared by polymerization with different types and amounts of monomers. The molecular weight and distribution of the above-mentioned polymers P1-P8 were tested by GPC 2410 gel permeation chromatography, and the results are shown in Table 1. As can be seen from Table 1, the introduction of carbazole units in the phenothiazine conjugated system can significantly increase the molecular weight of the polymer; by changing the feed ratio and optimizing the reaction conditions, higher molecular weight polymers can be obtained; A long alkyl chain is introduced into the group, which can make all polymers have good solubility, and they are all soluble in common organic solvents, such as toluene, chloroform, tetrahydrofuran, etc.

Table 1. Molecular weight and distribution of each polymer

a: o-DCB is used as the solvent, CuCl and TMEDA are used as the catalyst, and air is introduced at 50°C for 30 minutes;

b: Measured by GPC, THF is the solvent, and polystyrene is the reference substance.

2. UV absorption, fluorescence emission peak and thermogravimetric analysis of fluorescent conjugated polymers containing phenothiazine groups:

Measure the ultraviolet-visible absorption spectrum of above-mentioned polymer P1～P8 by HP8453E type ultraviolet-visible spectrometer, record the fluorescence emission spectrum of above-mentioned polymer by Fluorolog-3 type fluorescence spectrometer, and measure the above-mentioned polymer by Netzsch TG209F1 type thermal analyzer The thermal properties were tested and analyzed, and the results are shown in Table 2. It can be seen from Table 2 that except for polymer P5 which emits purple light, other polymers all emit bright green light; the decomposition temperature of the polymer is between 373°C and 426°C Between them, the residual carbon content at 800°C is above 60%, which has good thermal stability.

Table 2. Absorption emission peaks and thermal stability of each polymer

polymer UV absorption wavelength ^a Fluorescence emission wavelength ^b Onset decomposition temperature residual carbon content

(nm) (nm) (°C) ^c (%) P1 412 501 413 63 P2 350,386 503 — — P3 352,382 497 409 66 P5 321, 352 412 426 61 P7 410, 488 498 373 61

a: UV absorption wavelength in chloroform;

b: fluorescence emission wavelength in chloroform;

c: Thermogravimetric analysis under nitrogen protection with a heating rate of 10°C/min.

3. Analysis of ultraviolet absorption and fluorescence emission of fluorescent conjugated polymers containing phenothiazine groups in different solvents: by changing the type of solvent, the concentration of polymer P7 in n-hexane, toluene, chloroform, acetone and N, N -UV-Vis absorption spectrum and fluorescence emission spectrum in dimethylformamide, the results are shown in Table 3. It can be seen from Table 3 that in different solvents, the shift of the UV absorption peak changes very little, indicating that the solvent has little influence on its ground state. In different solvents, the fluorescence emission peaks red-shifted to a certain extent with the increase of polarity, indicating that such fluorescent conjugated polymers with D-π-A structure can be used as fluorescent sensor materials.

Table 3. Optical properties of polymer P7 in different solvents

solvent UV absorption wavelength ^a (nm) Fluorescence emission wavelengthb ⁽ nm) n-Hexane 390, 480 482 toluene 408, 482 498 Chloroform 410, 488 498 acetone 404, 476 501 N,N-Dimethylformamide 410, 476 511

a: UV absorption wavelength in chloroform;

b: Fluorescence emission wavelength in chloroform.

4. Electrochemical analysis of fluorescent conjugated polymers containing phenothiazine groups:

The redox potentials of polymers P1, P3 and P7 were determined by cyclic voltammetry. CHI 660A point chemical workstation was adopted, and a standard three-electrode electrochemical cell was used for determination; the platinum electrode was used as the working electrode and the auxiliary electrode, and the calomel electrode (SCE) was used as the reference electrode. Table 4 shows the electrochemical performance analysis results of the fluorescent conjugated polymers containing phenothiazine groups. It can be seen from Table 4 that the HOMO energy levels of polymers P1, P3, and P7 are all around -5.60eV, all of which have good hole transport properties; the LUMO energy level of polymer P7 is -3.34eV, which is relatively The oxazine homopolymer is reduced, which is beneficial to electron injection.

Table 4. Electrochemical performance of polymer ^a

a: Carried out in 0.1M tetrabutylammonium hexafluorophosphate-acetonitrile solution. The working electrode is a platinum electrode, the reference electrode is a calomel electrode, the platinum wire is an auxiliary electrode, and the scanning speed is 50mV/s.

5. NMR analysis of fluorescent conjugated polymers containing phenothiazine groups:

NMR of N-octyl-3,6-bis(ethynyl)phenothiazine, N-octyl-3,6-bis(ethynyl)carbazole and fluorescent conjugated polymer P3 containing phenothiazine groups The resonance diagram is shown in Figure 1, where A is N-octyl-3,6-bis(ethynyl)phenothiazine, B is N-octyl-3,6-bis(ethynyl)carbazole, and C is Copolymer P3;

N-octyl-3,6-bis(ethynyl)phenothiazine, 4,7-diethynyl-2,1,3-benzothiaxazole and fluorescent conjugated polymers containing phenothiazine groups The nuclear magnetic resonance pattern of P7 is shown in Figure 2, where A is N-octyl-3,6-bis(ethynyl)phenothiazine, and B is 4,7-diethynyl-2,1,3-benzene And thiaxazole, C is the copolymer P7.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (4)

1. A fluorescent conjugated polymer containing a phenothiazine group, characterized in that the structural formula is: Wherein, x is a natural number from 2 to 100, y is a natural number from ₂ to 200; R1 is an alkyl group with ₁ to 18 carbons; R2 is N-octylcarbazole or benzothiaxazole. 2. the synthetic method of the fluorescent conjugated polymer containing phenothiazine group according to claim 1, is characterized in that comprising the steps: (1) Synthesis of N-alkyl-3,6-bis(ethynyl)phenothiazine monomer: 3,6-dibromo-N-alkylphenothiazine and divalent palladium catalyst are added to the reactor , add cuprous iodide, under the protection of nitrogen, add toluene, triethylamine and 3,3'-dimethyl-3-hydroxypropyne, heat up the reaction, filter the reaction product, wash with anhydrous ether, Atmospheric pressure distillation removes solvent, obtains intermediate with column chromatography purification; Under nitrogen protection, the intermediate and NaOH were heated and refluxed in toluene solvent, the toluene solvent was distilled off under reduced pressure, and purified by column chromatography to obtain N-alkyl-3,6-bis(ethynyl)phenothiazine mono body; (2) Synthesis of fluorescent conjugated polymers containing phenothiazine groups: N-alkyl-3,6-bis(ethynyl) phenothiazine monomers obtained in step (1) and N-octyl-3 , 6-bis(ethynyl)carbazole monomer or 4,7-diethynyl-2,1,3-benzothiaxazole monomer was dissolved in o-dichlorobenzene, stirred until completely dissolved to obtain a mixed solution ; Then the resulting mixed solution is transferred to the catalytic system containing cuprous chloride and tetramethylethylenediamine, under the condition of feeding air, the reaction is stirred; after the reaction is finished, the reaction solution is poured into a mixture of methanol and concentrated hydrochloric acid Precipitate in the mixed solution, filter, and vacuum-dry the filtered solid to obtain the fluorescent conjugated polymer containing phenothiazine groups; The molar ratio of the 3,6-dibromo-N-alkylphenothiazine to the divalent palladium catalyst in step (1) is 1: (0.02～0.05), and the 3,6-dibromo-N-alkyl The molar ratio of phenothiazine to cuprous iodide is 1:(0.001～0.005), in terms of mole fraction, 6～15mL of toluene is added to every mmol of 3,6-dibromo-N-alkylphenothiazine, three Ethylamine 6-15mL, 3,3'-dimethyl-3-hydroxypropyne 0.3-1.5mL, the temperature of the heating reaction is 80-120°C, the reaction time is 10-24h, the intermediate and NaOH The molar ratio is 1:(1~2), the temperature of the temperature rising reflux reaction is 80~120°C, and the reaction time is 3~10h; Step (2) said N-alkyl-3,6-bis(ethynyl)phenothiazine monomer and N-octyl-3,6-bis(ethynyl)carbazole monomer or 4,7-bis The molar ratio of ethynyl-2,1,3-benzothiaxazole monomer is 1:(1~3), the temperature for stirring until complete dissolution is 20~60°C, and the stirring reaction time is 4 ~60min, the catalytic system containing cuprous chloride and tetramethylethylenediamine uses 20~30mg of cuprous chloride, 0.06~0.08mL of tetramethylethylenediamine and adjacent 20-50 mL of dichlorobenzene is prepared, and the mixed solution of methanol and concentrated hydrochloric acid is prepared by mixing 50-100 mL of methanol and 0.1-0.3 mL of concentrated hydrochloric acid per millimole of diacetylenic monomer, and the said diacetylenic monomer is N- Alkyl-3,6-bis(ethynyl)phenothiazine monomer and N-octyl-3,6-bis(ethynyl)carbazole monomer or 4,7-diethynyl-2,1,3 - the sum of benzothiaxazole monomers. 3. The synthesis method according to claim 2, characterized in that: the alkyl carbon number of the 3,6-dibromo-N-alkylphenothiazine in step (1) is 1-18. 4. The application of the fluorescent conjugated polymer containing phenothiazine groups according to claim 1 in the fields of organic light-emitting devices, solar cells and fluorescent sensors.