Aromatic ketone two-photon initiator, preparation method, composition and application

Abstract

The invention discloses an aromatic ketone two-photon initiator, a preparation method, a composition and application, and relates to the technical field of photoinitiators, the two-photon initiator releases alkaline species through photoinduced decarboxylation under near-infrared femtosecond laser irradiation and catalyzes anion two-photon polymerization reaction, efficient two-photon 3D printing is achieved, and the aromatic ketone two-photon initiator has the advantages of high-efficiency two-photon 3D printing, high-efficiency two-photon 3D printing and high-efficiency two-photon 3D printing. The problems of large polymerization volume shrinkage, harsh working conditions and corrosion of acidic species generated in the curing process to a metal substrate in the current free radical two-photon polymerization and cationic two-photon polymerization are solved; the method shows huge application potential in the fields of high-density optical information storage, micro-nano optical device processing, biological scaffold construction and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of photoinitiators, and in particular to an aromatic ketone two-photon initiator, a preparation method, a composition and an application thereof. Background Art

[0002] With its high spatial resolution and excellent controllability, two-photon polymerization technology has become an important means to construct micro-nanoscale three-dimensional structures, and has shown great application potential in the fields of high-density optical information storage, micro-nano optical device processing, and biological scaffold construction. As the core component of the two-photon polymerization formula system, the performance of the two-photon initiator has a significant impact on the efficiency, printing accuracy, and terminal material performance of two-photon 3D printing. Its mechanism of action is: under femtosecond laser irradiation, the initiator molecule absorbs two near-infrared photons, causing the electron to transition from the ground state to the excited state, and then the excited state initiator molecule produces active species, which in turn triggers the polymerization of monomers or oligomers, realizing the transformation of the polymer material system from liquid to solid. At present, two-photon initiators mainly produce two active species after photolysis: free radicals and cations.

[0003] The polymerization reaction initiated by free radical active species has a significant speed advantage and greater flexibility and diversity in the selection of raw materials. However, this type of polymerization reaction has the problem of reducing the printing accuracy of the final product due to the large shrinkage of the polymer material. In addition, free radical polymerization is easily affected by oxygen inhibition, resulting in a decrease in the mechanical properties of the printed structure.

[0004] The polymerization reaction initiated by cationic active species overcomes the limitations of free radical polymerization in some aspects, especially in reducing the shrinkage of polymerized materials. However, the acidic species generated during cationic polymerization can have an adverse effect on the properties of metal substrates and terminal cured materials. This acidic environment may cause corrosion of metal materials or affect the stability of cured materials, thus limiting its application in certain fields. In addition, cationic polymerization is difficult to carry out in an environment with high humidity, so a more stringent working environment is required. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present application provides an aromatic ketone two-photon initiator, a preparation method, a composition and an application. The aromatic ketone two-photon initiator of the present invention contains a long conjugated structure of D-π-A-π-D (D represents an electron-donating group, A represents an electron-withdrawing group, and π represents a carbon-carbon triple bond), has a large two-photon absorption cross section, and under near-infrared femtosecond laser irradiation, the terminal phenylglycine structure can release alkaline species by photodecarboxylation, and such active species can effectively catalyze anionic polymerization systems such as Michael addition reaction, thiol-epoxy resin, thiol-isocyanate resin, etc., to achieve efficient two-photon 3D printing, overcome the large shrinkage of polymerization volume in current free radical two-photon polymerization and cationic two-photon polymerization, harsh working environment and acidic species generated during curing process to metal substrate corrosion problems, and has great application potential in microelectronics processing fields such as high-density optical information storage and micro-nano optical device construction.

[0006] In a first aspect, the present application provides an aromatic ketone two-photon initiator, the chemical structure of which is shown below:

[0007]

[0008] Wherein, Z represents any one of the following chemical structural formulas:

[0009]

[0010] G + Represents any one of the following chemical structural formulas:

[0011]

[0012] The second aspect of the present application provides a method for preparing the two-photon initiator, comprising the following steps:

[0013] The following steps are involved:

[0014] Reaction 1: N-(4-ethynylphenyl)-N-methylglycine methyl ester and M undergo Sonogashira coupling reaction in the presence of a catalyst and an acid binding agent to obtain intermediate a; the specific reaction formula is as follows:

[0015]

[0016] Wherein, M is an aromatic ketone derivative which is dihalogenated at any position of the aromatic ring.

[0017] (2) Intermediate a is hydrolyzed under the action of a base catalyst and then acidified to obtain intermediate b; the specific reaction formula is as follows:

[0018]

[0019] (3) Dispersing the intermediate b and an organic base in a solvent for reaction, removing the solvent, and obtaining the target product; the specific reaction formula is as follows:

[0020]

[0021] In the reaction 1, the molar ratio of N-(4-ethynylphenyl)-N-methylglycine methyl ester to the dihalogenated aromatic ketone derivative is 1:1 to 1:4; preferably, the molar ratio of N-(4-ethynylphenyl)-N-methylglycine methyl ester to the dihalogenated aromatic ketone derivative is 1:2 to 1:3;

[0022] The catalyst is composed of catalyst 1 and catalyst 2, wherein catalyst 1 comprises any one or a mixture of two or more of the following: bistriphenylphosphine palladium dichloride, palladium acetate, bistriphenylphosphine nickel dichloride, triphenylphosphine; preferably, catalyst 1 is bistriphenylphosphine palladium dichloride;

[0023] Catalyst 2 includes any one of the following: cuprous iodide, cuprous bromide, cuprous chloride; preferably, catalyst 2 is cuprous iodide;

[0024] The acid binding agent includes any one of the following or a mixture of two or more thereof: triethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide, sodium hydride; the preferred acid binding agent is triethylamine;

[0025] The reaction temperature is 25-120°C, preferably 40-80°C;

[0026] The N-(4-ethynylphenyl)-N-methylglycine methyl ester, in which the N-phenylglycine in the structure can effectively realize the decarboxylation reaction.

[0027] In the reaction 2, the hydrolysis reaction is carried out under the action of an alkaline catalyst at 25 to 80° C. for 1 to 8 hours, and then an acid is added dropwise to produce a precipitate;

[0028] Preferably, the hydrolysis reaction is carried out at 40 to 60° C. for 2 to 4 hours under the action of an alkaline catalyst, and then an acid is added dropwise to produce a precipitate;

[0029] In the hydrolysis reaction, the alkali catalyst is any one of sodium hydroxide and potassium hydroxide or a mixture of two or more thereof.

[0030] In the hydrolysis reaction, the acid is any one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid, or a mixture of two or more thereof.

[0031] In the reaction 3, the reaction temperature of the intermediate product b and the organic base dispersed in the solvent is 20 to 60° C., and the reaction time is 1 to 12 hours. The solvent is any one of water, methanol, ethanol, tetrahydrofuran, and N,N-dimethylformamide, or a mixture of two or more thereof. The organic base includes 1,5,7-triazabicyclo[4.4.0]undec-5-ene (TBD), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), tetramethylguanidine or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN).

[0032] The third aspect of the present application provides a composition comprising the aromatic ketone two-photon initiator described in the present application.

[0033] The composition includes a photoresist, or a photocuring agent for additive manufacturing.

[0034] A preferred embodiment of the photoresist, wherein the components of the photoresist further include thiol derivatives and isocyanate derivatives, the thiol derivatives include pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate) or 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione or a mixture of two or more thereof; the isocyanate derivatives include xylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate or a mixture of two or more thereof.

[0035] The fourth aspect of the present application provides the application of the two-photon initiator described in the present application in the field of biological scaffold construction, micro-nano processing or three-dimensional optical storage.

[0036] The application of the micro-nano processing field includes two-photon 3D printing.

[0037] Beneficial effects of this application:

[0038] (1) The aromatic ketone two-photon initiator of the present application contains a long conjugated structure of D-π-A-π-D and has a large two-photon absorption cross section. Under near-infrared femtosecond laser irradiation, the terminal phenylglycine structure can release alkaline species through photodecarboxylation, catalyze anionic polymerization reaction, and realize efficient two-photon 3D printing. It overcomes the problems of large polymerization volume shrinkage, harsh working environment and corrosion of metal substrates by acidic species generated during the curing process in current free radical two-photon polymerization and cationic two-photon polymerization, and has great application potential in microelectronic processing fields such as high-density optical information storage and micro-nano optical device construction.

[0039] (2) The two-photon initiator has a large two-photon absorption cross section due to its long conjugated structure of D-π-A-π-D. It can not only realize near-infrared femtosecond laser irradiation printing, but also realize printing at a lower threshold laser power, which can be as low as 1 mW.

[0040] (3) Compared with carbazole two-photon initiators, the aromatic ketone two-photon initiators described in the present application can achieve decarboxylation of the terminal phenylglycine to release alkaline species under low threshold laser power and near-infrared femtosecond laser irradiation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is the UV-visible absorption spectrum of the two-photon initiator described in Example 3 of the present invention;

[0042] Figure 2 is the UV-visible absorption spectrum of the two-photon initiator described in Example 6 of the present invention;

[0043] Figure 3 is the UV-visible absorption spectrum of the phenol red solution in Example 10 of the present invention;

[0044] Figure 4 This is a scanning electron microscope image of the microstructure obtained in Example 12 of the present invention;

[0045] Figure 5 This is a scanning electron microscope image of the microstructure obtained in Example 13 of the present invention. DETAILED DESCRIPTION

[0046] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0047] Embodiment 1:

[0048] Preparation of intermediate 1a:

[0049]

[0050] 430 mg of 3,6-diiodobenzophenone and 14 mg of bistriphenylphosphine palladium dichloride were dissolved in 30 mL of deoxygenated dry tetrahydrofuran, and 500 mg of N-(4-ethynylphenyl)-N-methylglycine methyl ester, 30 mL of deoxygenated dry triethylamine, and 3.8 mg of cuprous iodide were added in sequence under argon protection. The reaction mixture was heated to 80 ° C and stirred. The progress of the reaction was monitored by thin layer chromatography. After the reaction was completed, the solution was poured into 200 mL of deionized water and extracted with ethyl acetate until the water layer became colorless. The organic layer was washed with deionized water (3×50 mL) and saturated brine (2×50 mL), dried over anhydrous sodium sulfate, filtered, and the solvent was removed by reduced pressure distillation. Purification by column chromatography, the eluent was a 1:3 petroleum ether-chloroform mixed solution, and 230 mg of the product was obtained with a yield of 40%.

[0051] Embodiment 2:

[0052] Preparation of intermediate 1b:

[0053]

[0054] 100 mg of intermediate 1a and 12 mg of potassium hydroxide were dispersed in 10 mL of ethanol and reacted at 50°C for 4 hours. After cooling to room temperature, dilute hydrochloric acid was added dropwise to the ethanol solution until the orange-red precipitate no longer precipitated. After filtration and drying, 90 mg of the product was obtained with a yield of 95%.

[0055] Embodiment 3:

[0056] Preparation of two-photon initiator:

[0057]

[0058] 80 mg of intermediate 1b was dispersed in 10 mL of methanol, and a methanol solution containing 40 mg of TBD was added dropwise. The mixture was reacted at 30° C. for 1 hour in a 50 mL single-necked flask. The methanol was removed under reduced pressure to obtain 114 mg of a two-photon initiator with a yield of 95%. 1 HNMR(400MHz,Chloroform-d)δ7.72(d,J=8.2Hz,4H),7.54(d,J=8.2Hz,4H),7.32(d,J=8.7Hz,4H),6.53(d,J =8.9Hz, 4H), 4.32 (s, 4H), 3.21 (t, J = 5.9Hz, 8H), 3.12 (td, J = 5.9, 2.1Hz, 8H), 3.06 (s, 6H), 1.91 ~ 1.87 (m, 8H).

[0059] Embodiment 4:

[0060] Preparation of intermediate 2a:

[0061]

[0062] 340 mg of 2,7-dibromofluorenone and bistriphenylphosphine palladium dichloride were dissolved in 30 mL of deoxygenated dry tetrahydrofuran, and 0.50 g of N-(4-ethynylphenyl)-N-methylglycine methyl ester, 30 mL of deoxygenated dry triethylamine, and 3.8 mg of cuprous iodide were added in sequence under argon protection. The reaction mixture was heated to 80 ° C and stirred. The progress of the reaction was monitored by thin layer chromatography. After the reaction was completed, the solution was poured into 200 mL of deionized water and extracted with ethyl acetate until the water layer became colorless. The organic layer was washed with deionized water (3×50 mL) and saturated brine (2×50 mL), dried with anhydrous sodium sulfate, filtered, and the solvent was removed by reduced pressure distillation. Purification by column chromatography, the eluent was a 1:4 petroleum ether-chloroform mixed solution, and 205 mg of the product was obtained with a yield of 35%.

[0063] Embodiment 5:

[0064] Preparation of intermediate 2b:

[0065]

[0066] 100 mg of intermediate 2a and 13 mg of potassium hydroxide were dispersed in 10 mL of ethanol and reacted at 60°C for 2 hours. After cooling to room temperature, dilute hydrochloric acid was added dropwise to the ethanol solution until no dark red precipitate was precipitated. After filtration and drying, 88 mg of product was obtained with a yield of 93%.

[0067] Embodiment 6:

[0068] Preparation of two-photon initiator:

[0069]

[0070] 78 mg of intermediate 2b was dispersed in 10 mL of methanol, and a methanol solution containing 40 mg of TBD was added dropwise. The mixture was reacted at 25° C. for 2 hours in a 50 mL single-necked flask. The methanol was removed under reduced pressure to obtain 112 mg of a two-photon initiator with a yield of 95%. 1 H NMR(400MHz,Chloroform-d)δ7.76(d,J=1.4Hz,2H),7.59(dd,J=7.8,1.4Hz,2H),7.46(d,J=7.8Hz,2H),7.37(d,J=8.8Hz,4 H), 6.58 (d, J = 8.9Hz, 4H), 4.27 (s, 4H), 3.24 (t, J = 5.9Hz, 8H), 3.11 (td, J = 5.9, 2.1Hz, 8H), 3.02 (s, 6H), 1.96 ~ 1.81 (m, 8H).

[0071] Embodiment 7:

[0072] The accurate concentration is 5×10 -5 The initiator tetrahydrofuran solution obtained in Example 3 was tested for its UV-visible absorption spectrum, and it was found that the maximum absorption peak of the two-photon initiator obtained in the present invention was at 420nm. Its UV absorption spectrum is as follows Figure 1 shown.

[0073] Embodiment 8:

[0074] The accurate concentration is 5×10 -5 The initiator tetrahydrofuran solution obtained in Example 6 was tested for its UV-visible absorption spectrum, and it was found that the maximum absorption peak of the two-photon initiator obtained in the present invention was at 410nm, and the tail absorption extended to above 550nm. Its UV absorption spectrum is as follows Figure 2 shown.

[0075] Embodiment 9:

[0076] The photoinitiators obtained in Example 3 and Example 6 were dissolved in tetrahydrofuran, respectively. The two-photon absorption cross sections at 800 nm were tested by open-aperture Z-scan and were found to be 316 GM and 420 GM, respectively.

[0077] Embodiment 10:

[0078] The accurate concentration is 7.62×10 -5 The initiator acetonitrile solution obtained in Example 6 was placed in a quartz cuvette, and a drop of the indicator phenol red acetonitrile saturated solution was added. The solution was continuously irradiated for 2 hours under a femtosecond laser with a wavelength of 800 nm, a femtosecond laser pulse of 80 fs, a scanning speed of 60 μm / s, and a laser power of 5 mW. The intensity change of the characteristic absorption peak of the phenol red solution at 570 nm before and after irradiation was monitored. Figure 3 As shown, after irradiation, the characteristic absorption peak at 570nm is enhanced due to the decomposition of the photoinitiator to release the strong base TBD.

[0079] Embodiment 11:

[0080] The accurate concentration is 3.62×10 -3 The initiator methanol solution obtained in Example 6 was irradiated for 2 hours under a femtosecond laser with a wavelength of 800 nm, a femtosecond laser with a pulse of 80 fs, a scanning speed of 60 μm / s, and a laser power of 3 mW. Before irradiation, the pH of the solution was 7.18. After irradiation, the pH value of the solution rose to 10.25 due to the decomposition of the photoinitiator to release the strong base TBD.

[0081] Embodiment 12:

[0082] Under light-proof conditions, 2 mg of the initiator obtained in Example 6, 300 mg of isophorone diisocyanate and 435 mg of pentaerythritol tetrakis(3-mercaptopropionic acid) ester were added to a glass container equipped with a stirrer, and the mixture was stirred and shaken until the initiator was completely dissolved to obtain a two-photon photoresist, which was applied to a glass slide and processed under a femtosecond laser with a wavelength of 800 nm, a femtosecond laser with a pulse of 80 fs, a printing speed of 60 μm / s and different laser powers. It was found that the threshold of the two-photon initiator of the present invention was low, and the threshold was 1 mW. Figure 4 shown.

[0083] Embodiment 13:

[0084] Under light-proof conditions, 2 mg of the initiator obtained in Example 6, 300 mg of isophorone diisocyanate and 435 mg of pentaerythritol tetrakis(3-mercaptopropionic acid) ester were added to a glass container equipped with a stirrer, and the mixture was stirred and shaken until the initiator was completely dissolved to obtain a two-photon photoresist, which was applied to a glass slide and processed under a femtosecond laser with a wavelength of 800 nm, a femtosecond laser with a pulse of 80 fs, a printing speed of 60 μm / s and a laser power of 5 mW to obtain a three-dimensional microstructure with good precision, such as Figure 5 shown.

Claims

1. An aromatic ketone two-photon initiator, whose chemical structure is as follows: in, Z represents any one of the following chemical structural formulas: G + Represents any one of the following chemical structural formulas:

2. The method for preparing the aromatic ketone two-photon initiator according to claim 1, Features: The following steps are involved: Reaction 1: N-(4-ethynylphenyl)-N-methylglycine methyl ester reacts with M in the presence of a catalyst and an acid-binding agent to undergo a Sonogashira coupling reaction to obtain intermediate a; Wherein, M is an aromatic ketone derivative dihalogenated at any position of the aromatic ring; Reaction 2: Intermediate a is hydrolyzed under the action of a base catalyst and then acidified to obtain intermediate b; Reaction 3: Disperse the intermediate b and the organic base in a solvent for reaction, remove the solvent, and obtain the target product. The structural formula of the target product is as above.

3. The method for preparing the aromatic ketone two-photon initiator according to claim 2, Features: In the reaction 1: The catalyst is composed of catalyst 1 and catalyst 2, wherein catalyst 1 comprises any one of the following or a mixture of two or more thereof: bistriphenylphosphine palladium dichloride, palladium acetate, bistriphenylphosphine nickel dichloride, triphenylphosphine; and catalyst 2 comprises any one of the following: cuprous iodide, cuprous bromide, cuprous chloride; The acid binding agent includes any one of the following or a mixture of two or more thereof: triethylamine, sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide, sodium hydride; The reaction temperature is 25-120°C; Or / and, in the reaction 2: The base catalyst includes any one of sodium hydroxide and potassium hydroxide or a mixture of two or more thereof; the acid includes any one of hydrochloric acid, sulfuric acid, nitric acid and acetic acid or a mixture of two or more thereof; The hydrolysis reaction is carried out under the action of an alkaline catalyst at 25-80° C. for 1-8 hours, and then an acid is added to produce a precipitate.

4. The method for preparing the aromatic ketone two-photon initiator according to claim 3, Features: In the reaction 1: The molar ratio of N-(4-ethynylphenyl)-N-methylglycine methyl ester to the dihalogenated aromatic ketone derivative is 1:1 to 1:4; the catalyst 1 comprises bistriphenylphosphine palladium dichloride, the catalyst 2 comprises cuprous iodide; the acid binding agent comprises triethylamine; and the reaction temperature is 40 to 80°C.

5. The method for preparing the aromatic ketone two-photon initiator according to claim 2, Features: In the reaction 3: The organic base includes 1,5,7-triazabicyclo[4.4.0]undec-5-ene, 1,8-diazabicyclo[5.4.0]undec-7-ene, tetramethylguanidine or 1,5-diazabicyclo[4.3.0]non-5-ene; Or / and, the solvent is any one of water, methanol, ethanol, tetrahydrofuran, N,N-dimethylformamide or a mixture of two or more thereof; Or / and, the reaction temperature of the intermediate product b and the organic base dispersed in a solvent is 20 to 60° C., and the reaction time is 1 to 12 hours.

6. A composition, Features: The invention comprises the aromatic ketone two-photon initiator as described in claim 1.

7. The composition according to claim 1, Features: The composition includes a photoresist, or a photocuring agent for additive manufacturing.

8. The composition according to claim 7, Features: The components of the photoresist also include thiol derivatives and isocyanate derivatives. The thiol derivatives include one or a mixture of two or more of pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptobutyrate) or 1,3,5-tris (3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6 (1H, 3H, 5H)-trione; the isocyanate derivatives include one or a mixture of two or more of xylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate or diphenylmethane diisocyanate.

9. Use of the aromatic ketone two-photon initiator according to claim 1, Features: The applications include applications in the field of biological scaffold construction, micro-nano processing or three-dimensional optical storage.

10. Use of the aromatic ketone two-photon initiator according to claim 9, Features: The application of the micro-nano processing field includes two-photon 3D printing.

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