CN109776471B - A kind of coumarin-type organic third-order nonlinear optical material and its preparation and application - Google Patents

Abstract

The invention relates to a coumarin type organic third-order nonlinear optical material, which takes coumarin as a core group, and connects arylamine derivatives at the 6-position of the core group, wherein the arylamine derivatives comprise N, N-dimethylbenzene, triphenylamine and carbazole phenyl. The preparation mainly comprises the following steps: adding a coumarin derivative substituted by bromine at the 6-position, an arylamine derivative of pinacol borate and potassium carbonate into a solvent for dissolving; introducing nitrogen for 30min, adding a palladium tetratriphenylphosphine catalyst, heating to 80-100 ℃, reacting for 6-24 h at 1000-1200 r/min; extracting with dichloromethane and distilled water for several times, separating liquid, and drying; the obtained crude product is separated and purified. According to the invention, arylamine derivatives are introduced to the 6-position of coumarin to form a large D-Pi-A configuration, so that the nonlinear absorption coefficient and the two-photon absorption cross section value of coumarin molecules can be increased, and the coumarin compound can be applied to third-order nonlinear optical materials. The preparation method is simple, easy to operate, easy to obtain raw materials, low in cost and high in application value.

Description

A kind of coumarin-type organic third-order nonlinear optical material and its preparation and application

technical field

The invention belongs to the field of organic third-order nonlinear optical materials, in particular to a coumarin-type organic third-order nonlinear optical material and its preparation and application in the third-order nonlinear optical field.

Background technique

Coumarin compounds are a class of substances with their own aromatic odor. These compounds have a benzopyrone structure and are widely distributed in plants in nature. They are a class of natural products with important functions. Due to the particularity of the coumarin ring structure, it can be structurally modified at many positions. According to the electron-withdrawing or electron-donating properties of the introduced modification group, the entire coumarin compound molecule can form a new electronic conjugated structure. In addition, there is a large conjugated system formed by C=C and C=O double bonds in the coumarin molecule itself, and the lactone structure in the coumarin ring also plays a role in enhancing the rigidity of the molecule, so this The special internal structure enables coumarin compounds to produce relatively strong fluorescence in the visible light range, and at the same time makes their photon quantum stability and photoluminescence quantum yield relatively high. Therefore, coumarin compounds are generally used to produce functional materials that can play a role in photoelectric response. At present, coumarin is rarely used in third-order nonlinear optical materials.

Organic nonlinear optical materials have the advantages of multiple relationship between absorption wavelength and emission wavelength, fast response time, and easy processing into high-quality optical devices. They have great potential significance in information technology and industrial applications. The two-photon absorption effect is a phenomenon of light-excited molecules under laser light, which belongs to the third-order nonlinear optical effect. The molecule simultaneously absorbs two photons of the same or different frequencies, producing a very high transient photon density. Organic compounds with large two-photon cross-sections have a wide range of applications in three-dimensional data storage, precision machining, microscopy, up-conversion lasers, photodynamic therapy, etc., and have become a research hotspot for scientists in recent years. Coumarin-based materials have good light, thermal and chemical stability, light absorption characteristics and high fluorescence quantum yield, large molar absorptivity and electron delocalization, making them a potential nonlinear precursor material. Therefore, it is of practical significance to study the application of coumarin-type materials in third-order nonlinear optical materials and develop a coumarin-type organic nonlinear optical material.

Contents of the invention

The object of the present invention is to provide a coumarin-type organic third-order nonlinear optical material and its preparation and application, so as to solve the problems existing in the prior art.

A coumarin-type organic third-order nonlinear optical material, which uses coumarin as a core group and connects arylamine derivatives at the 6-position of the core group.

The substituent is an arylamine derivative, and arylamine, as a kind of dye with mild chemical property, low toxicity and environment-friendly, is also commonly used in the synthesis of medicine. From the perspective of application, the coumarin-arylamine system has great potential.

At present, most of the substitution positions of the coumarin type occur at the 1-position. The present invention finds that the substitution position at the 6-position can effectively expand the conjugation range of the system, making the molecule form a large D-π-A configuration, which is beneficial to Increase the β (non-linear absorption coefficient) value of the coumarin molecule.

Further, the arylamine derivatives include N,N-dimethylbenzene, triphenylamine and carbazolephenyl. Triphenylamine has more benzene rings and a larger conjugated system than N,N-dimethylaniline. The two benzene rings of the carbazolephenyl group are fixed by a carbon-carbon single bond and cannot rotate freely, and the coplanarity is improved. The present invention selects these three groups to study the influence of small changes in structure on the two-photon absorption cross-section value.

Further, the para-position of the N,N-dimethylbenzene is connected to the 6-position of the coumarin group.

Further, the 4-position of the triphenylamine is connected to the 6-position of the coumarin group.

Further, the 4-position of the carbazole phenyl group is connected to the 6-position of the coumarin group.

The coumarin-type organic third-order nonlinear optical material of the invention has good two-photon absorption properties, and the maximum absorption cross-section value is as high as 103.6GM. The two-photon absorption cross-section values of very classic materials reported publicly, such as fluorescein, rhodamine B and rhodamine 6G, are only tens to more than a hundred GM.

The preparation of the above-mentioned coumarin-type organic third-order nonlinear optical material mainly includes the following steps:

(1) preparing coumarin derivatives after bromination at the 6-position;

(2) by Suzuki coupling reaction, the 6-brominated coumarin derivative, the arylamine derivative of boric acid pinacol ester and potassium carbonate are added to the solvent for dissolution;

(3) After passing nitrogen for 30 minutes, add tetrakis-triphenylphosphine palladium catalyst, heat to 80-100°C, 1000-1200r/min, and react for 6-24 hours;

(4) multiple extractions with dichloromethane and distilled water, liquid separation, drying to obtain the crude product;

(4) The obtained crude product was separated and purified on a 200-300 mesh silica gel column using dichloromethane/n-hexane as the eluent.

The application of the above-mentioned coumarin-type organic third-order nonlinear optical material is applied to the third-order nonlinear optical material.

Further, including microscopy, precision machining, 3D data storage, optical power confinement, up-conversion lasers, photodynamic therapy, and photorelease.

Compared with the prior art, the present invention introduces an electron-donating group arylamine derivative on the 6-position of coumarin, so that the molecule forms a large D-π-A configuration, which is beneficial to increase the non-toxicity of the coumarin molecule. Linear absorption coefficient and two-photon absorption cross-section value, with high two-photon absorption characteristics, can be applied to third-order nonlinear optical materials, microscopy, precision processing, three-dimensional data storage, optical power limitation, up-conversion laser, photodynamic therapy, photorelease etc. Moreover, the preparation method of the invention is simple, easy to operate, easy to obtain raw materials, low in cost, and has great application value.

Description of drawings

Fig. 1 is a coumarin structural diagram;

Fig. 2 is the structural diagram of the compound A that embodiment 1 obtains;

Fig. 3 is the structural diagram of the compound B that embodiment 2 obtains;

Fig. 4 is the structural diagram of the compound C that embodiment 3 obtains;

Figure 5 is a schematic diagram of Z-scan technology;

Fig. 6 is the ultraviolet absorption spectrum and fluorescence spectrum diagram of compounds A, B and C prepared in Examples 1, 2 and 3, respectively, wherein Fluorescence 1, Fluorescence 2 and Fluorescence 3 represent Compounds A, B and C respectively.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

Example 1

A kind of preparation of coumarin type organic nonlinear optical material A mainly comprises the following steps:

(1) Prepare the coumarin derivatives after bromination at the 6-position first:

First react coumarin and liquid bromine in dichloromethane solution at room temperature for 48 hours, wash with a large amount of saturated sodium carbonate solution, extract with dichloromethane, remove excess solvent by rotary evaporator, use methanol recrystallization, filter and dry to obtain yellow Solid powder, the crude product was separated and purified on a 200-300 mesh silica gel column using dichloromethane-n-hexane (volume ratio 2:5) as the eluent to obtain a coumarin derivative after bromination at the 6-position.

(2) Then prepare the coumarin derivatives substituted by p-position N,N-dimethylbenzene:

It mainly includes the following steps: take the coumarin derivative (500mg, 2.2mmol) after the bromination of the 6th position, and introduce the N,N-dimethylbenzene derivative of boric acid pinacol ester (618mg, 2.5mmol) at the para-position And K ₂ CO ₃ (133mg), dissolved with toluene ethanol mixed solution (3:1, 80ml). After passing nitrogen gas for 30 minutes, add 15 mg tetrakistriphenylphosphine palladium catalyst to the solvent, heat to 80°C, 1000r/min, and react for 8 hours. After the reaction, cool to room temperature, wash with a large amount of water, extract with dichloromethane, remove excess solvent with a rotary evaporator, add 100 mL of dichloromethane solution to dissolve the solid, wash with 40 mL of distilled water, and separate the layers. Use anhydrous sodium sulfate to remove the remaining water, separate the liquid, and dry. The crude product was separated and purified on a 200-300 mesh silica gel column using dichloromethane-n-hexane (volume ratio 2:5) as the eluent to obtain yellow compound A as shown in Figure 2.

The yield of the coumarin-type organic nonlinear optical material compound A obtained by the above-mentioned preparation method was 60%.

Example 2

A kind of preparation of coumarin type organic nonlinear optical material B mainly comprises the following steps:

(1) According to the method of Example 1, the brominated coumarin derivative at the 6-position was prepared.

(2) Prepare the coumarin derivatives substituted by triphenylamine:

It mainly includes the following steps: take the brominated coumarin derivative (500mg, 2.2mmol) at the 6th position, introduce the derivative of boric acid pinacol ester at the 4th position of triphenylamine (927mg, 2.5mmol) and K ₂ CO ₃ (133mg), dissolved with toluene ethanol mixed solution (3:1, 80ml). After passing nitrogen gas for 30 minutes, add 15 mg tetrakistriphenylphosphine palladium catalyst to the solvent, heat to 80°C, 1000r/min, and react for 8 hours. After the reaction, cool to room temperature, wash with a large amount of water, extract with dichloromethane, remove excess solvent with a rotary evaporator, add 100 mL of dichloromethane solution to dissolve the solid, wash with 40 mL of distilled water, and separate the layers. Use anhydrous sodium sulfate to remove the remaining water, separate the liquid, and dry. The crude product was separated and purified on a 200-300 mesh silica gel column using dichloromethane-n-hexane (volume ratio 1:4) as the eluent to obtain yellow compound B as shown in Figure 3.

The yield of the coumarin-type organic nonlinear optical material compound B obtained by the above-mentioned preparation method was 62%.

Example 3

A kind of preparation of coumarin-based organic nonlinear optical material C, its reaction formula is as follows, mainly comprises the following steps:

(1) According to the method of Example 1, the brominated coumarin derivative at the 6-position was prepared.

(2) Prepare the coumarin derivatives substituted by carbazole phenyl:

It mainly includes the following steps: taking the brominated coumarin derivative (500mg, 2.2mmol) at the 6th position, introducing the derivative of boric acid pinacol ester (922mg, 2.5mmol) at the 4th position on the carbazole phenyl group and K ₂ CO ₃ (133mg) was dissolved in a mixed solution of toluene and ethanol (3:1, 80ml). After passing nitrogen gas for 30 minutes, add 15 mg tetrakistriphenylphosphine palladium catalyst to the solvent, heat to 80°C, 1000r/min, and react for 8 hours. After the reaction, cool to room temperature, wash with a large amount of water, extract with dichloromethane, remove excess solvent with a rotary evaporator, add 100 mL of dichloromethane solution to dissolve the solid, wash with 40 mL of distilled water, and separate the layers. Use anhydrous sodium sulfate to remove the remaining water, separate the liquid, and dry. The crude product was separated and purified on a 200-300 mesh silica gel column using dichloromethane-n-hexane (volume ratio 1:4) as the eluent to obtain a white compound C as shown in Figure 4.

The yield of the coumarin-type organic nonlinear optical material compound C obtained by the above-mentioned preparation method was 41%.

Example 4

The effect of choosing coumarin as the parent, N,N-dimethylbenzene, triphenylamine and carbazole phenyl as different substituents on the overall third-order nonlinear characteristics.

The coumarin-based organic nonlinear optical material compounds A, B, and C prepared in Examples 1, 2, and 3 were applied to third-order nonlinear optical materials, and their third-order nonlinear absorption coefficient, third-order nonlinear optical material were measured by Z-scan technology. Linear refractive index and two-photon absorption cross-section values.

The principle of Z-scanning technology is shown in Figure 5: the specific steps are: the laser light emitted from the laser is attenuated by the attenuator A, the lens L focuses the light beam, and a beam splitter is placed in front of the lens to divide the laser light into two beams, and one beam directly enters the The detector D1 is used to measure the transmitted light after passing through the small hole, and the other beam passes through a small hole whose center coincides with the optical axis and then enters another detector D2 to measure the change of the input light. Fix the test sample compound A on a moving rack with a scale, and the position of the sample is read from the scale. Take the focal point as the origin of the coordinates, and move the sample along the Z axis before and after the focal point. As the sample moves along the light propagation direction (Z direction) near the focal point, due to the nonlinear effect of the medium, the beam will diverge or converge, so normalize The normalized transmittance T(D1/D2) will have a one-to-one relationship with the sample position, and the normalized beam transmittance can be expressed as:

是有效长度，L为样品长度，β为非线性吸收系数。双光子吸收系数通过公式(1)拟合实验测得的透过率数据得出，然后通过公式δ＝hωβ/(2πN₀)计算出双光子吸收截面值，其中，hω/(2π)是激发光子能量，N₀是每立方厘米分子数目。双光子吸收截面值通常用GM表示，1GM＝1×10^-50cm⁴s/photon。Among them, Z represents the distance between the sample and the focusing center, Z ₀ represents the Rayleigh diffraction length, l ₀ is the peak power density,

is the effective length, L is the sample length, and β is the nonlinear absorption coefficient. The two-photon absorption coefficient is obtained by fitting the transmittance data measured by the experiment with the formula (1), and then the two-photon absorption cross-section value is calculated by the formula δ=hωβ/(2πN ₀ ), where hω/(2π) is the excited Photon energy, N ₀ is the number of molecules per cubic centimeter. The value of the two-photon absorption cross section is usually represented by GM, 1GM=1×10 ^-50 cm ⁴ s/photon.

Table 1 Two-photon absorption coefficients and two-photon absorption cross-section values of compounds A, B, and C

The measured third-order nonlinear optical properties of compounds A, B, and C are shown in Table 1. Through Z-scanning, it is found that they all have good two-photon absorption coefficient and absorption cross-section value, especially the two-photon absorption coefficient of compound B reaches 7.84×10 ^-12 cm W ^-1 , with a two-photon absorption cross section of 103.6GM. It has good two-photon absorption effect and is suitable for third-order nonlinear optical materials.

The coumarin-based organic nonlinear optical material compounds A, B, and C prepared in Examples 1, 2, and 3 were tested for ultraviolet absorption spectrum and fluorescence spectrum, and Rhodamine 6G aqueous solution (ΦFL=0.76) was used as a fluorescence standard. The test spectrum is shown in Figure 6, and the test data are shown in Table 2. It can be concluded that the emission wavelengths of compounds A-C are 579, 570 and 510 nm, respectively.

Table 2 UV absorption spectrum and fluorescence spectrum data of compounds A, B and C measured in CH ₂ Cl ₂ .

The coumarin-based organic nonlinear optical material compounds A, B, and C prepared in Examples 1, 2, and 3 were tested by cyclic voltammetry, and the oxidation-reduction potential of compounds A-C was measured by cyclic voltammetry, and then the formula [b ] to calculate the corresponding LUMO, HOMO and energy gap.

Table 3 The relevant data of compounds A, B, C measured by cyclic voltammetry

[a] Measured in 0.05M tetrabutylammonium hexafluorophosphate dichloromethane solution (vs. SCE) under argon atmosphere. [b] E _HOMO = -(4.4eV+E _oxi(1) ). [c] Calculated based on the DFT of the rb3lyp/6-311g(d) module under the Gaussian 09 program.

Through the above analysis and comparison, it can be known that compound B formed by substituting triphenylamine at the 6-position of coumarin has the best third-order nonlinear properties, which are much higher than the other two structures. Molecules illustrating the structure of compound B are most favorable for application to third-order nonlinear optical materials.

Exploration of the mechanism. The invention finds the experimental quantitative relationship between the two-photon absorption cross section value and the molecular structure by fitting the lifetime of the excited state charge separation state. The experiments were performed to fit the lifetimes of the coumarin-based organic nonlinear optical material compounds A, B, and C prepared in Examples 1, 2, and 3, and four lifetime values were obtained. Lifetime 1 (τ ₁ ) is the internal conversion process from the higher excited singlet state (S _n ) to the first excited singlet state (S ₁ ); lifetime 2 (τ ₂ ) is the transition from the first excited singlet state (S ₁ ) to Intramolecular charge transfer process of singlet excited state charge-separated state (CS*); lifetime 3(τ ₃ ) is the intersystem transition from singlet excited state charge-separated state (CS*) to triplet excited state charge-separated state (CS ₃ ) The crossover process; lifetime 4 (τ ₄ ) is the external conversion process from the triplet excited charge-separated state (CS ₃ ) to the ground state (S ₀ ). Among them, the lifetime 3 represents the lifetime of the charge-separated singlet excited state. The present invention finds that this lifetime can be used as an experimental criterion for the quantitative relationship between the two-photon absorption cross-section value and the molecular structure. It is not difficult to obtain by comparison that the order of size of the lifetime 3 (τ ₃ ) is: C<A<B; the order of size of the two-photon absorption cross section is: C<A<B. The two-photon absorption cross-section value is linearly related to the hole-electron center distance (Δr) of the excited state. The larger the Δr, the farther the center distance between the holes and electrons in the excited state is, and the time for the holes and electrons to recombine is shorter. The longer it is, the longer the lifetime of the excited-state charge-separated state.

Table 4. Lifetime fitting of compounds A, B, and C

The above descriptions are only preferred embodiments of the present invention, and should not be used to limit the scope of rights of the present invention. Therefore, the equivalent changes made according to the claims of the present invention still belong to the scope covered by the present invention.

Claims (4)

1. A coumarin-type organic third-order nonlinear optical material, characterized in that, taking coumarin as a core group, connecting arylamine derivatives at the 6 positions of the core group, the compound of the following formula:

The arylamine derivatives include carbazole phenyl; the 4-position of the carbazole phenyl is connected to the 6-position of the coumarin group. 2. the method for preparing the described coumarin type organic third-order nonlinear optical material of claim 1 is characterized in that, mainly comprises the following steps: (1) Prepare the coumarin derivatives after bromination at the 6-position, such as the compound of the following formula:

(2) Through the Suzuki coupling reaction, the coumarin derivatives after bromination at the 6-position, the arylamine derivatives of boric acid pinacol esters and potassium carbonate are added to the solvent for dissolution, as shown in the following formula: Base amine derivatives:

(3) After passing nitrogen for 30 minutes, add tetrakis-triphenylphosphine palladium catalyst, heat to 80-100°C, 1000-1200r/min, and react for 6-24 hours; (4) multiple extractions with dichloromethane and distilled water, liquid separation, drying to obtain the crude product; (5) The obtained crude product was separated and purified on a 200-300 mesh silica gel column using dichloromethane/n-hexane as the eluent. 3. The application of the coumarin type organic third-order nonlinear optical material according to claim 1, characterized in that it is applied to the third-order nonlinear optical material. 4. The application according to claim 3, characterized in that it includes microscopy, precision machining, three-dimensional data storage, optical power limitation, up-conversion laser, and photorelease.

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