CN101348537A - Triphenylamine-naphthalene branched molecules with two-photon polymerization initiation properties - Google Patents

Abstract

The invention discloses a triphenylamine-naphthalene multi-branch molecule with two-photon polymerization initiation characteristics. Using triphenylamine as the electron donor, the 4, 4'-positions of triphenylamine are respectively connected to the naphthalene ring with electron acceptor characteristics through carbon-carbon double bonds to form a "Y-pn junction" topology with charge transfer capability, and then With the "Y-pn junction" as the connection center, the substituents are conjugated and connected to form a multi-branched molecule of a larger conjugated system, so it has a large two-photon absorption cross section. It has excellent two-photon polymerization initiation ability for methacrylic resin, low polymerization threshold, and high degree of microstructure obtained by polymerization processing, and has application value in two-photon three-dimensional storage and photonic crystal microprocessing.

Description

Triphenylamine-naphthalene branched molecules with two-photon polymerization initiation properties

technical field

The invention relates to a class of triphenylamine-naphthalene multi-branch molecules, which have strong two-photon absorption properties and excellent two-photon polymerization initiation properties for methacrylic resins.

Background technique

Two-photon absorption refers to the process of exciting the sample with a light source nearly twice the linear absorption wavelength of the sample under strong light excitation, so that it directly absorbs two photons through a virtual intermediate state and jumps to a high-energy state. The absorption and dispersion of light with a longer wavelength are small, and the light wave has strong penetrating ability, and because the transition probability is proportional to the square of the incident light intensity, the excited range of the sample is limited to λ ³ under the condition of tight focusing of the laser beam. Within the volume, the excitation is highly spatially selective. These characteristics of two-photon absorbing materials make them have attractive application values in the fields of two-photon polymerization microfabrication, high-density optical storage, photonic crystals, and two-photon fluorescence microscopy.

Two-photon three-dimensional micromachining is a new type of photopolymerization technology developed in recent years. In the two-photon polymerization system, the long-wavelength laser with strong penetrating ability is used to initiate the two-photon polymerization reaction, which can limit the size of the polymerization reaction to the order of microns, submicrons or even nanometers, so that deep three-dimensionality can be realized in the polymerization system micromachining. For example, a photonic crystal is a periodic microstructure that can be adjusted to light waves, and has the characteristic of adjusting the motion state of photons. At present, two-photon photopolymerization technology is the easiest way to make periodic microstructures of photonic crystals. Therefore, two-photon polymerization microjunction fabrication technology has attracted worldwide attention. In 2001, Japanese scientist Kawata et al. used ultrashort pulse laser to induce photoresist to undergo two-photon polymerization, and used near-infrared femtosecond pulse laser with a wavelength of 780nm to carve a red blood cell-sized bull image (called "nano cow"). ), its laser processing resolution has reached 120nm, breaking through the diffraction limit of traditional optical theory, and realizing the use of two-photon processing technology to manufacture three-dimensional structures with submicron precision. The emergence of "nano cattle" has aroused people's great attention to two-photon processing technology, and related research work has been carried out extensively in countries all over the world. In view of the high-precision and high-density three-dimensional processing characteristics of two-photon polymerization technology, it is expected to be widely used in photonic devices, micro-electromechanical systems and other fields in the near future.

In two-photon polymerization technology, it is required that the active species (commonly referred to as photoinitiator) that initiates photopolymerization can absorb two photons at the same time, thereby generating active species (free radicals or ions) to initiate the polymerization reaction. At present, there is no commercial product of an efficient two-photon polymerization initiator. Although the use of traditional ultraviolet photoinitiators (such as Benzil) to initiate polymerization of resins has been reported in three-dimensional microfabrication, due to the small two-photon absorption cross-section of the initiator molecule, This leads to low polymerization efficiency, low photosensitivity and low resolution of the polymerization system. Therefore, the development of high-efficiency two-photon polymerization initiators has always been one of the hot spots in this field.

Contents of the invention

The purpose of the present invention is to provide a triphenylamine-naphthalene multi-branched molecule with strong two-photon absorption properties and excellent two-photon polymerization initiation properties for methacrylic resins.

In order to achieve the above object, the technical solution adopted in the present invention is: a kind of triphenylamine-naphthalene multi-branched molecule with two-photon polymerization initiating characteristics, is to be electron donor (D) with triphenylamine, respectively in 4,4 of triphenylamine The '-position is connected to the naphthalene ring with electron acceptor characteristics (A) through a carbon-carbon double bond, forming a "Y-pn junction" topology, with the "Y-pn junction" as the connection center, and conjugated to connect substituent groups Triphenylamine-naphthalene multi-branch molecule, its structural formula is:

In the formula, R _is selected from one of H, carboxyl, bromine atom, bromonaphthyl, 4-vinylpyridyl, 4-N, N diphenylaminostyryl;

R ₂ and R ₃ are respectively selected from one of H, carboxyl group, bromine atom, 4-vinylpyridyl group, and 4-N,N-diphenylaminostyryl group.

Among them, the "Y-shaped-pn junction" topology has a strong intramolecular charge transfer capability. With the "Y-pn junction" as the connection center, different substituents are conjugated to form a multi-branched molecule of a large conjugated system. Has strong two-photon absorption properties.

In the above-mentioned technical scheme, when R ₁ is -bromonaphthyl, R ₂ and R ₃ are bromine atoms at the same time, the molecular structural formula is,

When one substituent is H or carboxyl, and the other two are triphenylamine groups connected by carbon-carbon double bonds, the molecular structural formulas are respectively,

When the substituent is 4-bromonaphthalene or a pyridine group connected by a carbon-carbon double bond, the molecular structural formulas are respectively,

When the substituent is 4-bromonaphthalene or a triphenylamine group connected by a double bond, the molecular structural formula is respectively,

For the preparation method of the above-mentioned compound molecule of the present invention, please refer to the description in the examples.

Due to the use of the above-mentioned technical solutions, the present invention has the following characteristics compared with the prior art:

1. In the present invention, the triphenylamine group is connected with the naphthalene ring to form a "Y-shaped-pn junction" topological center, and then conjugated with different substituents to form a multi-branched molecule of a large conjugated system, thus having strong two-photon absorption. Under the excitation of 800 femtosecond Ti:Sapphire laser (300mW, repetition frequency 140Hz), it has obvious two-photon absorption ability; as the two-photon absorption cross section of the compound of Example 2 reaches 2312GM (see Table 1);

2. The compound of the present invention has a "Y-shaped-pn junction" topological center and has strong intramolecular charge transfer characteristics. Under the excitation of light, the molecule is prone to charge separation to form free radicals after absorbing two photons, and has a good Radical polymerization initiating characteristics; using laser micromachining technology, using the example compound as an initiator, the research on the two-photon polymerization initiating characteristics of methacrylic resin (see Table 2). The results show that when the scanning speed is 10 μm/s, the two-photon polymerization threshold of the example compound is 38kJ/cm ² , the polymerization threshold is low, and the fineness of the processed microstructure is high, (under the same conditions, the traditional initiator bibenzoyl The polymerization threshold is 290kJ/cm ² ), which is a kind of excellent two-photon polymerization initiator.

Description of drawings

Fig. 1 is the two-photon fluorescence spectrum (THF, 1×10 ^-4 M) of Example 2 under laser pumping at different wavelengths;

Figure 2 is the two-photon absorption cross section (THF, 1×10 ^-4 M) of Example 2 under laser pumping at different wavelengths;

Fig. 3 is the two-photon absorption cross-section (DMF, 1×10 ^-4 M) of Examples 4-6 under different wavelength laser pumps;

Fig. 4 is to take embodiment 4 as two-photon initiator, realizes the photonic crystal microstructure scanning electron microscope picture after two-photon polymerization process to methacrylic resin (top view, microstructure size is: 20 μ m * 20 μ m; grid size: 0.6 μ m ×0.6μm);

Fig. 5 is a partial enlarged view of Fig. 4;

Fig. 6 is a side view of Fig. 4 (inclination angle: 45°);

Fig. 7 is a scanning electron micrograph of a "micro-cow" (bull size: 20 μm×20 μm) after two-photon polymerization of methacrylic resin with Example 5 as a two-photon initiator.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and embodiment:

Example 1: Synthesis of 4,4',4"-tris(4-bromo-1-naphthylvinyl)triphenylamine.

(1) Preparation of 4,4',4"-triphenylamine trialdehyde: under a nitrogen atmosphere, first place 2.4g (0.62mol) of 4,4',4"-triphenylamine tribromide in a three-necked flask, seal the After degassing, 30 mL of dry THF was injected, 3.5 mL of dry DMF was injected at -78°C, and 15.6 mL of n-butyllithium was injected dropwise with stirring. After dripping, react at -78°C for 3 hours, then react at room temperature for 3 hours, stop the reaction, pour the reaction solution into a saturated aqueous solution of NH ₄ Cl, extract with CH ₂ Cl ₂ , separate the organic layer, concentrate and reweight with petroleum ether. After precipitation, a yellow solid powder was obtained with a yield of 67%. MS(EI)M ⁺ =329, ¹ H NMR(CDCl ₃ , 300MHz): δ9.92(s, 3H), 7.84(d, 6H), 7.24(d, 6H).

(2) Add 0.4g (1.3mmol) of 4-bromo-1-bromomethylnaphthalene, 0.384g (1.4mmol) of triphenylphosphine and 10ml of xylene into a 100ml three-necked flask, reflux at 120°C for 6h, and pump out after cooling. Filter, take the filter residue, and recrystallize from absolute ethanol to obtain 4-bromo-1-bromomethyl naphthalene quaternary phosphorus salt (0.71g), the yield is 95%, and the melting point is >280°C.

(3) 4-bromo-1-bromomethyl naphthalene quaternary phosphorus salt (5.12g, 9.12mmol), 4,4',4"-triphenylamine trialdehyde (1.0g, 3.04mmol), 1,4-di Oxycycline (80ml) and sodium hydride (0.36g, 15.0mmol) were added to a 250ml three-necked flask, refluxed at 110°C for 6h, after cooling, suction filtered, the filtrate was taken, concentrated, and prepared with ethyl acetate:petroleum ether=1:3 The eluent was separated by column chromatography to obtain 1.15 g of the compound of Example 1 with a yield of 46%. MS (MALDI) M ⁺ =935.0, elemental analysis (%): Cald.69.10; H, 3.87; N, 1.49.Found. 68.73; H, 3.26; N.1.98.

The molecular formula of the obtained compound is,

Example 2: Synthesis of 4,4'-bis(4-triphenylaminovinylnaphthyl-1-vinyl)triphenylamine.

(1) Preparation of 1-bromo-4-(1-ethylenetriphenylamine)naphthalene: 4-bromo-1-bromomethylnaphthalene quaternary phosphonium salt (0.3g, 0.53mmol) obtained in step 2 of Example 1 and 4- N,N-Diphenylaminobenzaldehyde (0.08g, 0.3mmol) and sodium hydride (0.042g, 1.75mmol) were added to a 100ml three-necked flask, refluxed at 110°C for 6h, cooled, filtered, and the filtrate was taken, concentrated, petroleum Ether was the eluent and separated by column chromatography to obtain yellow 1-bromo-4-(1-ethylenetriphenylamine)naphthalene (0.064 g) with a yield of 40%. MS (EI) M ⁺ =476, elemental analysis (%): Cald. C, 75.63; H, 4.65; N, 2.94. Found.75.04; H, 4.16; N.3.28.

(2) 4,4'-bis(4-triphenylaminovinylnaphthyl-1-vinyl)triphenylamine preparation: under anhydrous and oxygen-free conditions, 0.253g (0.53mmol) 1-bromo-4- (1-ethylenetriphenylamine) naphthalene, 0.08g (0.27mmol) N, N-bis (4-styrene) aniline, 10ml triethylamine and 8ml acetonitrile as solvent, 0.008g o-methyltriphenylphosphine and 0.0024g Palladium acetate was added as a catalyst into a 100ml three-necked flask, refluxed at 85°C for 24h, concentrated after cooling, and separated by column chromatography using chloroform:petroleum ether=3:1 as the eluent to obtain 0.058g of the target compound. Yield 26%, mp: 134-135°C, MS (MALDI) M ⁺ = 1087.7. Elemental analysis (%): Cald.C, 90.49; H, 5.65; N, 3.86. Found.90.05; H.6.02; N .3.24.

The molecular formula of the obtained compound is,

Example 3: Synthesis of 4,4'-bis(4-triphenylaminovinylnaphthyl-1-vinyl)-N,N-diphenylaminobenzoic acid.

The synthetic method is similar to Example 2, only need to change N, N-bis(4-styrene) aniline in step 2 into N, N-bis(4-styrene)-4-aminobenzoic acid according to the obtained compound . Yield 21%, MS (MALDI) M ⁺ = 1132.30. Elemental analysis (%): Cald.C, 88.03; H, 5.43; N, 3.71.Found.88.50; H.5.02; N.3.24.

The molecular formula of the obtained compound is,

Example 4: Synthesis of 4,4'4"-tris(4-vinylpyridyl-1-naphthylvinyl)triphenylamine.

Under anhydrous and oxygen-free conditions, 1.0g (1.07mmol) 4,4',4"-three (4-bromo-1-naphthylvinyl) triphenylamine (compound of Example 1), 0.12ml (1.07mmol) Add 4-vinylpyridine, 10ml triethylamine and 8ml acetonitrile as solvent, 0.0162g o-methyltriphenylphosphine and 0.0048g palladium acetate as catalyst into a 100ml three-necked flask, reflux reaction at 85°C for 24h, cool and concentrate, and dilute with acetic acid Ethyl ester:petroleum ether=5:1 is the eluent and separated by column chromatography to obtain 0.125g of the compound of Example 4, with a melting point of 88-89°C. MS (MALDI)=960.16 (M ⁺ ). Elemental analysis (%): Cald .C, 76.10; H, 4.40; N, 2.91. Found.C, 76.42; H, 4.21; N, 3.22.

The molecular formula of the obtained compound is,

Embodiment 5: The synthesis method is similar to that of Example 4, only 4,4',4 "-three (4-bromo-1-naphthylvinyl) triphenylamine (compound of Example 1) and 4- Vinylpyridine, reacted at a molar ratio of 1:2. Yield 46%, melting point 115 ° C. MS (MALDI) = 897.3 (M ⁺ ). Elemental analysis (%): Cald.C, 82.75; H, 4.90; N, 4.26. Found. C, 82.36, H, 4.28; N, 4.58.

The molecular formula of the obtained compound is,

Embodiment 6: The synthesis method is similar to that of Example 4, only 4,4', 4 "-three (4-bromo-1-naphthylvinyl) triphenylamine (compound of Example 1) and 4- Vinylpyridine, reacted at a molar ratio of 1:3. Yield 40%, melting point 158°C. MS (MALDI) M ⁺ =1010.43. Elemental analysis (%): Cald.C, 89.08; H, 5.38; N, 5.54. Found. C, 88.68; H, 4.99; N, 5.91.

The molecular formula of the obtained compound is,

Example 7: The synthesis method is similar to that of Example 4, except that 4-vinylpyridine is changed to ethylenetriphenylamine according to the obtained compound. Yield 64%. MS (MALDI) M ⁺ = 1126.26. Elemental Analysis (%): Cald. C, 78.72; H, 4.64; N, 2.48. Found. C, 78.18; H, 4.16; N, 2.02.

The molecular formula of the obtained compound is,

Example 8: The synthesis method is similar to that of Example 5, except that 4-vinylpyridine is changed to ethylenetriphenylamine according to the obtained compound. Yield 56%, MS (MALDI) M ⁺ =1320.46. Elemental analysis (%): Cald.C, 85.57; H, 5.19; N, 3.18. Found.C, 85.02; H, 4.36; N, 3.64.

The molecular formula of the obtained compound is,

Example 9: The synthesis method is similar to that of Example 6, except that 4-vinylpyridine is changed to ethylenetriphenylamine according to the obtained compound, and the yield is 41%. MS (MALDI) M ⁺ = 1512.06.

The molecular formula of the obtained compound is,

The linear spectra and two-photon absorption properties of some triphenylamine-naphthalene branched molecules obtained in the examples are shown in Table 1 and Figures 1-3.

Table 2 shows the polymerization thresholds of the two-photon-initiated methacrylic polymerization system of some of the compounds in the examples.

The three-dimensional microstructures (such as microcows and photonic crystals, etc.) obtained by the polymerization process of the two-photon-initiated methacrylic polymerization system of some of the compounds in the examples are shown in Figures 4-7.

Table 1 Linear optical and two-photon absorption properties of triphenylamine-naphthalene branched molecules

Note: λ _max ^OPA represents the peak position of linear absorption spectrum (THF, 1×10 ^-5 mol dm ^-3 ); λ _max ^OPF and the peak position of single-photon fluorescence spectrum (THF, 1×10 ^-5 mol dm ^-3 ) ; Φ _f represents the fluorescence quantum yield (reference is fluorescein, Φ _f =0.9); λ _max ^TPF represents the peak position of two-photon fluorescence; λ _max ^TPF represents the maximum peak position of two-photon absorption; δ _TPA represents the two-photon absorption cross section ( 1GM=1×10 ⁻⁵⁰ cm ⁻⁴ ·s·photon ⁻¹ ·molecule ⁻¹ ). The two-photon absorption cross section is measured by two-photon fluorescence method (fluorescein is used as reference), and the excitation light source is a mode-locked Ti:sapphire femtosecond laser (wavelength adjustment range 700-880nm, repetition frequency 80MHz, pulse width 130fs, output power 0.3W ), the sample concentration is 1×10 ^-4 moldm ^-3 , THF solvent. ^a Measured in dichloromethane. ^b Measured in DMF.

Table 2 embodiment 4-6 compound is used as the polymerization threshold of two-photon initiator

Note: The compounds of Examples 4-6 were used as initiators to carry out two-photon polymerization of methacrylic resins, and their two-photon initiation characteristics in the same system and at the same concentration were investigated. For the convenience of comparison, a commercial photoinitiator, bibenzoyl, was introduced as a reference. The scanning speed is all: 10 μm/s.

Claims (1)

1. triphenylamine-naphthalin multi-branched molecule with two-photon polymerized initiation characteristic, it is characterized in that: be to be electron donor(ED) with the triphenylamine, respectively at 4 of triphenylamine, 4 '-position connects the naphthalene nucleus with electron acceptor(EA) characteristic by carbon-carbon double bond, constitute " Y-pn knot " topological framework, with " Y-pn knot " is the connection center, and conjugation connects triphenylamine-naphthalin multi-branched molecule that substituted radical forms, and its general structure is:

In the formula, R ₁Be selected from H, carboxyl, bromine atoms, bromo naphthyl, 4-vinylpyridine base, 4-N, a kind of in the N-diphenylamino styryl;

R ₂, R ₃Be selected from H, carboxyl, bromine atoms, 4-vinylpyridine base, 4-N respectively, a kind of in the N-diphenylamino styryl.

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