JPH10245498A - New 7-membered cyclic pigment material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new pigment compound having a compact size, high molecular absorption constant and excellent chemical and thermal stability, and applicable as a functional material such as a non-linear optical material as well as ordinary pigment material. SOLUTION: The objective compound is expressed by formula I [R<1> and R<2> are each H or a (substituted) lower alkyl; R<3> to R<6> are each H, a (substituted) lower alkyl or a lower alkoxy]. The compound can be produced e.g. by using a compound of formula II [R<3> to R<6> are each a (substituted) lower alkyl or a lower alkoxy] such as 4-bromo-N,N-dimethylaniline as a starting substance, dissolving the substance in anhydrous tetrahydrofuran, dropping a pentane solution of t-butyllithium and reacting with zinc chloride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel dye material, and can be used for controlling light by applying it to a non-linear optical material in addition to the use of conventional dyes such as dyeing and printing.

[0002]

2. Description of the Related Art Dye materials have been applied to various fields. One important and major application area is that of applying the color directly. This is because the coloring material develops color by absorbing visible light. For example, it is widely used not only for coloring fibers, plastics, metals, and the like, but also for recording and printing. In general, the performance required for a dye includes the ability to produce a dark color in a small amount (high molecular extinction coefficient), good chemical and thermal stability, and little degradation by light.

[0003] Non-linear optical materials are an application field of dyes different from conventional ones. Nonlinear optical materials are widely used for conversion and control of light, especially laser light, such as wavelength conversion of light, modulation of light by change in refractive index, and switching. This is understood as a phenomenon caused by the non-linear polarization of matter by an externally applied electromagnetic field. Here, when an electric field (light or electrostatic field) externally applied is E, and the polarization of a substance induced by the electric field is P, and P is expanded by E, the following equation (2) can be obtained.

[0004]

P = P ⁰ + χ ⁽¹⁾ E + χ ⁽²⁾ EE + χ ⁽³⁾ EEE + (2)

This χ ⁽²⁾ is called a second-order nonlinear susceptibility, and χ ⁽³⁾ is called a third-order nonlinear susceptibility.
Y. R. "Principles of N."
online Optics ".

At present, KDP (KH ₂ PO ₄ ) and LiNbO ₂ are actually used as nonlinear optical materials.
_The main materials are oxide single crystals such as ₃ (lithium niobate) and KTP (KTiOPO ₄ ), and semiconductor materials such as GaAs.
In recent years, π-electron conjugated organic compounds have attracted attention as this nonlinear optical material. This is because the nonlinear susceptibility is much higher than that of inorganic materials, and it is derived from electronic polarization. It depends on what is expected. In addition, it has a low dielectric constant, is more resistant to optical damage than lithium niobate, etc., is easier to manufacture for polymer materials than single crystal growth, and has various functions due to various molecular designs. May be added as a reason why the organic material is expected as a nonlinear optical material. Utilizing the features of such organic compounds, it is possible to fabricate wavelength conversion elements such as second-harmonic generation for low-power lasers such as semiconductor lasers, and electro-optic modulation elements with low-voltage driving and high-speed response. It is possible.

Various forms of organic materials have been studied as actual organic materials as nonlinear optical materials. For organic compounds, nonlinear susceptibility is discussed in terms of the hyperpolarizability of the molecule.
When an electric field acting on a molecule is E and a dipole moment of the molecule induced by the electric field is p, it can be expressed by the following equation (3).

[0008]

## EQU2 ## p = μ + αE + βEE + γEEE + (3)

Here, α is called the molecular polarizability, β and γ are called the secondary and tertiary molecular hyperpolarizabilities, respectively, and the nonlinear susceptibility of the molecular assembly is derived from these β and γ. As a second-order nonlinear optical material, an intramolecular charge-transfer material in which a molecule contains an electron-donating group and an electron-withdrawing group and is connected by a π-electron conjugated system is a secondary molecule. It has been shown that the hyperpolarizability (β) is large, and most of the organic compounds showing a large χ ⁽²⁾ known so far, as represented by methyl nitroaniline (MNA), Is a type of molecule.

However, the second-order nonlinear optical material has a limitation that its structure does not have macroscopic inversion symmetry. That is, since χ ⁽²⁾ is a third-order tensor, β
大 き く⁽²⁾ becomes 0 when the aggregate has a crystal structure having inversion symmetry or is amorphous even if is large. Therefore, how to orient a molecule having a large β into a polar structure is a major issue in searching for a material.

In this organic nonlinear optical material, the use of a crystal structure is most often performed.
The powder SHG method is a method for simply screening such a material. Heretofore, in order to obtain a crystal in which molecules are optimally arranged, several ideas for molecular design such as introduction of an optically active group, a skeleton having a small ground state dipole moment, and use of a hydrogen bond have been proposed.

However, the effect is not clear unless crystals are actually obtained. Further, the crystal of the organic compound is a molecular crystal and is soft and poor in workability. Further, when practically used as a nonlinear optical element, it is often desirable to process it into a waveguide structure. However, a method of forming a thin film, control of crystal orientation, and a method of partially changing a refractive index required for this are very important. Difficult. For this reason, despite the fact that a great number of organic crystals have been investigated for their potential as non-linear optical materials, there are currently only a few cases where elements have been processed into elements.

Another secondary organic nonlinear optical material is a polymer material. This is obtained by doping an acrylic polymer with a molecule having a large β such as Disperse Red 1 (N-ethyl-N-hydroxylethyl-4-amino-4′nitroazobenzene: see Comparative Example 1 described later). Or bonded to a side chain of a polymer. It is known that a polymer material is easy to form a thin film by coating and is an optical waveguide material excellent in optical properties, but a film just coated is generally amorphous and χ ⁽²⁾ is zero.方法 As a method for showing ⁽²⁾ , the polymer film is heated to a temperature equal to or higher than the glass transition temperature Tg while applying an electric field to orient the units having a large β, and then cooled to room temperature. The operation called poling, which fixes the orientation by performing the alignment, is most often used, and as a result, a material exhibiting an electro-optical effect on the order of lithium niobate has been obtained. However, the biggest disadvantage of this operation is that the orientation is thermally relaxed, and χ ⁽²⁾ is gradually attenuated. In addition, as a method for obtaining a structure in which units having a large β are oriented, use of an oriented film such as a Langmuir-Blodgett film has been attempted.

In any of the nonlinear optical materials, a material having a large χ ⁽²⁾ has many advantages for increasing the efficiency of the device. For example, in an optical switch element utilizing the electro-optical effect, if a material having a large electro-optical effect is used, a device driven at a low voltage can be obtained, and the length of the element can be shortened, which is advantageous for integration. Further, the dielectric constant of the organic material is about 3 to 4 and about 1/10 of that of lithium niobate, so that it can operate at a high speed of about 10 times in principle, and is applied to the high-speed optical communication field. It is advantageous.

Even in the application to such a nonlinear optical material, the proportion of molecules having a large hyperpolarizability contained in the material is often determined by the weight ratio, and therefore, the ratio of supermolecules per unit weight or per unit molecular weight is large. Molecules with large polarizability are preferred.

[0016]

A novel material which is compact, has a large molecular extinction coefficient, is excellent in chemical and thermal stability, and is applicable to functional materials such as nonlinear optical materials in addition to ordinary dye materials. Providing a novel dye molecule.

[0017]

The gist of the present invention is as follows.
And a dye compound represented by the following general formula (1).

[0018]

Embedded image

(Wherein, R ¹ and R ^{2 each} represent a hydrogen atom or a lower alkyl group which may be substituted, and R ^{3 to} R ^{6 each} represent a hydrogen atom or a lower alkyl group or a lower alkoxy group which may be substituted. .)

Second, a nonlinear optical material containing a dye compound represented by the general formula (1) and having a structure having no inversion symmetry. Thirdly, the above-mentioned nonlinear optical material is obtained by including a dye compound represented by the above general formula (1) in a polymer and applying an electric field while heating to orient the dye compound. It is a nonlinear optical polymer material.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present dye compound can be synthesized, for example, by the following synthetic route.

[0022]

Embedded image

As for R ^{1 to} R ⁶ , in addition to the hydrogen atom, R ¹ and R ² may be a lower alkyl group which may be substituted, R ³
As R ⁶ to R ^{6, a} lower alkyl group which may be substituted or a lower alkoxy group which may be substituted may be used, and those having 10 or less carbon atoms are preferable. Those containing a substituent reactive with the alkyl group or the alkoxy group, for example, an amino group, a hydroxyl group, a formyl group, a carboxyl group, a halogen atom, etc. It is preferable for synthesizing a derivative of or a polymer containing this dye. Examples of such derivatives include esters of acrylic acid and methacrylic acid, diols, diamines, dicarboxylic acids, and the like, which are useful for synthesizing polymers.

The dye compound of the present invention has an absorption band in the visible region and a molecular extinction coefficient sufficient for use as a dye. Further, it has a relatively small molecular weight and is chemically and thermally stable, and is expected to be applied to a wide range of applications. Examples of uses include dyeing of fibers, paper, plastic materials, and the like, ink, thermal transfer, and recording of information on optical disks and the like. These directly utilize the color of the dye.

A further important application example of the present dye is a nonlinear optical material. This dye is a so-called intramolecular charge transfer compound in which an electron-donating group and an electron-withdrawing group are bonded by conjugation of π electrons. It is known that such a dye has a large molecular hyperpolarizability β. Since the dye compound of the present invention has a very large β and a large permanent dipole moment, it is expected to exhibit high performance as a nonlinear optical material.

In order to use the dye compound of the present invention as a secondary nonlinear optical material, it is necessary to orient molecules in a polar structure. For this purpose, a method called so-called boring, in which the polymer containing the dye is oriented by heating to near the glass transition temperature (Tg) while applying an electric field, can be used. In addition, a Langmuir-Blodgett method in which both a hydrophilic group and a hydrophobic group are provided, a monomolecular film is formed on a water surface, and this is transferred to a substrate to obtain an alignment film can also be used. Furthermore, if a crystal having no inversion symmetry can be obtained directly or by introducing an appropriate substituent into the present dye compound, it will be a material exhibiting extremely high nonlinearity. If the large hyperpolarizability β of the present dye compound is used, no matter how the polar structure is obtained,
Very good nonlinear optical materials can be obtained.

In the nonlinear optical material, the above general formula (1)
Is preferably present at a concentration of 1% by weight or more, preferably 5% by weight or more. 100
%, That is, a material containing only a dye, it is necessary that its crystal structure does not show inversion symmetry in order to use it as a second-order nonlinear optical material. When a polar structure is obtained by poling in a polymer, the polymer is represented by the general formula (1)
It is more preferable to dissolve the dye of the present invention represented by the formula (1) above by chemically bonding the dye to the main chain or side chain of the polymer because the amount of the dye that can be introduced can be increased.

For example, R in the above general formula (1)¹To R⁶of
Arbitrary two include aminomethyl group, aminoethyl group,
An aminoalkyl group such as propyl
By reacting with a dicarboxylic acid such as an acid, the present invention
A polyamide having a dye in the main chain is obtained, and 4,4′-
Diisocyanate such as diphenylmethane diisocyanate
Reacting the dye of the present invention with the main chain
Is obtained. Similarly, R¹To R⁶
A hydroxymethyl group, a hydroxyethyl
And alkyl groups such as hydroxypropyl group
And 4,4'-diphenylmethane diisocyanate
Reaction with diisocyanate compounds such as
To obtain a polyurethane having the dye of the present invention in the main chain.
You. Also, R ¹To R⁶Any one of the aminoalkyl groups
And hydroxyalkyl groups, and acrylic acid
Chloride and methacrylic acid chloride
The amide compound and the ester compound are free from radical polymerization and anionic
Acrylic acid and / or other similar acrylic acid or
Monomers such as esters of tacrylic acid and styrene derivatives
Can be polymerized by mixing
And polymethacrylic acid esters are obtained. Others
By devising a substituent, a general polymer material, for example, poly
Styrene derivative, polycarbonate, polyester, poly
Can be incorporated into polyimide, polysiloxane, etc.
You.

Such a polymer compound exhibits a high Tg in order to suppress orientation relaxation after poling.
Alternatively, a material that can be cured by crosslinking or the like is preferable. Further, a nonlinear optical material is often used after being processed into a shape such as a waveguide and propagating light in the order of centimeters, and it is necessary that absorption is sufficiently small and transparent at the wavelength of the light to be used. Further, it is necessary to have excellent durability and mechanical strength.

Further, in order to suppress the orientation relaxation, the polymer skeleton is made to have a high glass transition temperature (Tg).
There is an effect that orientation is performed by poling at a high temperature to suppress relaxation at room temperature, or cross-linking treatment is performed before or after poling to suppress orientation relaxation. The thus obtained nonlinear optical material containing the dye compound of the present invention can be used as a material for producing a light modulation element or an optical switch element by utilizing its electro-optic effect. Further, if an appropriate wavelength is selected, the present invention can be applied to wavelength conversion elements such as sum and difference frequency generation including second harmonic generation, parametric amplification and oscillation.

By the way, the electric field induced second harmonic generation method (EFISH method) is often used for measuring the molecular hyperpolarizability, but this method is used for a dye that strongly absorbs the second harmonic light. difficult. Therefore, in the present invention, the following method was used. In general, the nonlinear susceptibility χ ⁽²⁾ obtained from the measurement of the nonlinear optical effect is obtained by averaging the molecular hyperpolarizability β in the distribution of molecular orientation. In the EFISH method, this is represented by a distribution of orientation in a dipole that can rotate freely in an electric field. From the previous studies on polarized polymer compounds, even when the polymer is heated to around the glass transition temperature, such a distribution is observed when the orientation ratio is small. ⁽²⁾ is well explained. Has been reported. However, in a system in which a dye molecule is simply dissolved in a polymer, orientation relaxation occurs quickly even at room temperature, and the orientation cannot be estimated.

In the present invention, the electro-optic effect was measured by keeping the DC voltage applied for orientation as it was, and superimposing an AC voltage on it. As a result, relaxation after the alignment does not occur, and it can be expected that the degree of the alignment is the same as when the mobility of the polymer is frozen. However, the orientation is gradually frozen when the temperature is lowered, and it is difficult to define a constant orientation temperature. However, even when the orientation is performed at 100 to 120 ° C. and the temperature is lowered to room temperature, the temperature is between the heating temperature and room temperature, and the effect is 300/393 = 0. Since it is within 76, the use of a heating temperature is sufficient as a method for evaluating a dye.

When a non-linear optical material in which the dye of the present invention is dissolved in a polymer is used as an element, as described above, it is oriented and then fixed by crosslinking or the like, or Tg is fixed. It is considered necessary to take measures such as selecting a high polymer. As a method of measuring the electro-optical effect used in the present invention, C.I. C. Teng et al. Ap
pl. Phys. Lett. 56, p 1734 (199
0) was used. However, this paper includes p
There is a defect in the calculation of the phase difference between the polarized light and the s-polarized light, and the formula for calculating r ₃₃ (the formula (10) in the paper) is

[0034]

(Equation 3)

Was used. FIG. 1 shows an example of a specific experimental layout. 1, 1 is a laser, 2 is a polarizer, 3 is a Babinet Soleil compensator, 4 is an analyzer, 5 is a photodiode, 6 is a lock-in amplifier, 7 is a power supply, 8 is a sample, 9 is a heater, 10 is an electrode and 11 is a temperature controller. Here, the difference from Teng et al. Is that the sample is fixed to the heat block, the temperature can be controlled by the temperature controller, and the applied voltage is such that the AC is applied with a DC offset. It is becoming. The required electro-optic coefficient r and χ
^{(2) The} following relationship with β was used.

[0036]

(Equation 4)

Where n is the refractive index, N is the number density of the dye, f
(Ω) is a local field correction coefficient of light or an electric field having a frequency ω, θ is an angle formed by the dipole μ of the molecule with the electric field, <> is an average, E is an externally applied electrostatic field, k is Boltzmann's constant, T Represents a temperature. f (ω) was reported by Singer et al. Chem. Ph
ys. 75, p. 3572 (1981). Thus, the μβ product is determined from the measurement of r. The electro-optic coefficient obtained by this measurement method depends on the effect of χ ⁽³⁾ by the DC electric field, namely the Kerr effect, the change in the refractive index due to the molecular orientation in the polymer due to the electric field at room temperature, and the electric field orientation of the polymer matrix itself. Although there are contributions such as the electro-optic effect, the effect is generally not large and can be used at least to compare the relative μβ products. In order to use the above equation, it is considered desirable to minimize the applied voltage and the concentration of the dissolved dye.

[0038]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as the gist is not exceeded. Example 1 2.18 g (10.9 mmol) of 4-bromo-N, N-dimethylaniline was dissolved in 10 ml of anhydrous tetrahydrofuran (THF), and stirred under a stream of argon gas at -72. 14.5 ml (1.58 g, 24.7 mmol) of 1.7 M tert-butyllithium solution in pentane at C
Was added dropwise over 20 minutes, and the mixture was stirred at the same temperature for 1 hour. Then under reduced pressure (about 0.5 mmHg) 200. A solution of 2.20 g (16.1 mmol) of zinc chloride which had been degassed and dried by heating for 2 hours at C was suspended in 20 ml of anhydrous THF dropwise at the same temperature over 5 minutes. After stirring at the same temperature for 20 minutes, the temperature was raised to room temperature over 1 hour to prepare a THF solution of 4- (N, N-dimethylamino) phenylzinc chloride.

At room temperature under a stream of argon gas, 0.47 g of bis (triphenylphosphine) palladium (II) chloride (0.7 mmo
l), 0.9 ml (0.19 g, 1.4 mmol) of 1.5 M diisobutylaluminum hydride in toluene and 3 ml of anhydrous THF
After separately adding a THF solution of 4- (N, N-dimethylamino) phenylzinc chloride to a palladium (0) catalyst separately prepared from 3-bromo-8,8-dicyanoheptafulvene 2.00
g (7.8 mmol) and anhydrous THF (10 ml) were added, and the mixture was further stirred at room temperature under an argon gas stream for 3 hours. 200 ml of ethyl acetate and 100 ml of 1M hydrochloric acid were added to the reaction solution, and the mixture was further stirred at room temperature for 30 minutes.
Extracted twice. The organic layers were combined, washed with saturated saline, dried over anhydrous magnesium sulfate and concentrated.

After dissolving the concentrated residue in an appropriate amount of methylene chloride, the residue was subjected to activated alumina column chromatography (60 g) and eluted with 200 ml of methylene chloride. Next, the eluate concentration residue is dissolved again in an appropriate amount of methylene chloride, and then subjected to silica gel column chromatography (110 g). From benzene to 5% diethyl ether-benzene, the polarity of the developing solvent (in 1% steps, 300 ml each) And eluted. The eluate was checked by thin-layer chromatography (silica gel, 2% diethyl ether-benzene), and fractions having the same Rf value were combined and concentrated to give 8,8-dicyano-3- [4-
(N, N-dimethylamino) phenyl] heptafulvene 1.62 g
(76% yield). Then, recrystallization from a methylene chloride-ethanol mixed solvent gave a melting point of 222 to 223. Red purple needles of C were obtained. Crystallization from a THF solution gave deep purple columnar crystals.

The analysis results of the obtained compound are shown below. Elemental analysis (%): Calculated as _{C 18 H 15 N 3 C:} 79.10 H: 5.53 N: 15.37 Found C: 78.93 H: 5.74 N: 15.15 Mass spectrum m / z 273 (M +, base peak) Infrared Absorption spectrum nmax (cm ^-1 ) 2200 (cyano group) ¹ H-NMR (CDCl ₃ ) d (ppm) 7.43 (dd, 1H, J = 11.9 and 2.0 Hz, 7-membered ring), 7.40
(d, 2H, J = 9.1 Hz, phenyl ring), 7.36 (dd, 1H, J =
11.9 and 2.0 Hz, 7-membered ring), 7.23 (ddd, 1H, J = 10.6,
2.0, and 2.0 Hz, 7-membered ring), 7.02 (m, 2H, 7-membered ring), 6.7
4 (d, 2H, J = 9.1 Hz, phenyl ring), 3.06 (s, 6H, -NMe
^{_{2) 13 C-NMR (CDCl}} 3) d (ppm) 162.59 (C-7), 151.32 (C-3), 140.25 (C-5), 138.96
(C-2), 134.59 (C-1), 132.24 (C-6), 131.64 (C-4), 1
28.36 (C-2U, C-6U), 126.88 (C-1), 115.54 and 115.45
(C-9, C-10), 112.2 (C-3U, C-5U), 66.31 (c-8), 40.1
1 (-NMe ₂ ) From the above analysis results, it was found that the obtained compound had the following molecular structure.

[0042]

Embedded image

When the visible absorption spectrum of the above compound in chloroform was measured, the absorption maximum (λma
x) is 458 nm and the molar extinction coefficient (ε) is 22000
Met. FIG. 2 shows the absorption spectrum.

Example 2 A cyclopentanone solution in which the dye obtained in Example 1 and polymethyl methacrylate (PMMA, manufactured by Aldrich Co., Ltd., medium molecular weight, intrinsic viscosity 0.45) were dissolved was spin-coated to form a film having a thickness of 2. A 7 μm film was prepared on a 300 Å ITO (indium-tin oxide) electrode. The dye concentration in the film was 6.9% by weight. After drying at 130 ° C. for 1 hour to remove the solvent, gold was vacuum deposited to a thickness of 1000 Å. Β was measured by the above-described method using the light of a 1.32 μm semiconductor laser-excited Nd-YAG laser. Polling is DC voltage 100V and AC voltage 10V
A voltage on which rms was superimposed was applied, and heating was performed at 110 ° C. for 10 minutes. After cooling to room temperature, the change in the refractive index due to the AC electric field was detected by the lock-in method while keeping the voltage unchanged. When the Pockels coefficient was determined from the change in the refractive index observed at this time, it was 1.1 pm / V. From this, the μβ product was determined to be 1200 × 10 ⁻⁴⁸ esu. At this time, f (0) ² f (ω) ² was assumed to be 7 as an internal electric field correction factor.

Comparative Example 1

[0046]

Embedded image

The μβ product was measured in the same manner as in Example 1 except that Disperse Red 1 (manufactured by Aldrich Co.) represented by the above molecular formula was used as the dye. The heating conditions at that time were 110 ° C. for 10 minutes, and the applied voltage used was a DC voltage of 100 V with an AC voltage of 20 Vrms superimposed.
The obtained μβ product was 825 × 10 ⁻⁴⁸ esu.

[0048]

As described in detail above, the dye compound of the present invention has a remarkably high molecular hyperpolarizability β. According to the nonlinear optical material of the present invention using such a dye for a nonlinear optical material, the nonlinear susceptibility is high. A high performance nonlinear optical material with significantly better efficiency is provided. Such a nonlinear optical material of the present invention is extremely useful industrially as a nonlinear optical material for controlling light by using it in an electro-optic light modulation element, a wavelength conversion element, or the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an apparatus used for measuring an electro-optic effect in the present invention.

FIG. 2 is a visible absorption spectrum of a dye synthesized in Example 1 in a chloroform solution.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Laser 2 Polarizer 3 Babinet Soleil compensator 4 Analyzer 5 Photodiode 6 Lock-in amplifier 7 Power supply 8 Sample 9 Heater
10 Electrode (ITO and gold) 11 Temperature controller

Claims (3)

[Claims] 1. A dye compound represented by the following general formula (1). Embedded image (In the formula, R ¹ and R ² represent a hydrogen atom or a lower alkyl group which may be substituted, and R ^{3 to} R ^{6 each} represent a hydrogen atom or a lower alkyl group or a lower alkoxy group which may be substituted.) 2. A nonlinear optical material comprising the dye compound according to claim 1 and having a structure having no inversion symmetry. 3. The non-linear optical material according to claim 2, wherein the dye compound according to claim 1 is contained in a polymer, or the non-linear optical material according to claim 1 is contained in a polymer main chain or side chain. A nonlinear optical polymer material obtained by applying an electric field while heating a dye compound chemically bonded thereto to orient the dye compound.