JP2762610B2 - Squarylium derivative and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel squarylium derivative useful as a nonlinear optical material and a method for producing the same.

2. Description of the Related Art In the fields of optical communication and optical information processing, nonlinear optical elements play an important role. The nonlinear optical material used for the nonlinear optical element is a light mixing that generates a sum frequency of two kinds of incident light having different frequencies, an optical parametric that becomes two kinds of light having different frequencies, and a change in refractive index of an optical medium. Pockels effect or Kerr effect, or the second harmonic of incident light (SH
G) or a substance that performs a very important function in optical signal processing such as conversion to the third harmonic (THG). Conventionally, such nonlinear optical materials include inorganic materials and organic materials. Things have been found.

For inorganic nonlinear optical materials, KDP (KH ₂ PO ₄ )
Crystals of inorganic compounds such as lithium niobate and lithium niobate (LiNbO ₃ ) are known, but have not been sufficient to satisfy the requirements.

On the other hand, organic nonlinear optical materials have recently attracted attention as materials for new optical elements in the field of optoelectronics, and have been actively studied year by year. In particular, organic compounds having a π-electron conjugate system have been extensively studied for material search because of the high performance and high-speed response of the molecule itself.

Generally, a crystal of an organic nonlinear optical material has a SHG coefficient 10 to 100 times larger than a crystal of an inorganic nonlinear optical material,
It is known that the light response speed is about 1000 times faster and the threshold value for light damage is large.

Conventionally known organic nonlinear optical materials include 2-
Methyl-4-nitroaniline, m-nitroaniline, N
-(4-nitrophenyl) -L-prolinol, 2-acetylamino-4-nitro-N, N-dimethylaniline,
4-dimethylamino-4'-nitrostilbene, 4'-
Dimethylamino-N-methyl-4-stilbazolium methyl sulfate and 4'-methylbenzylidene-4-
Organic compounds such as nitroaniline are exemplified. The nonlinearity of these organic compounds having a π-electron conjugate system is due to the interaction between laser light as an electromagnetic wave and the π-electrons of the organic compound. The size can be further increased by introducing an electron donating substituent.

However, such organic compounds generally have a large dipole moment, a strong dipole-dipole interaction during crystallization, and a centrally symmetric crystal having a structure in which two dipoles cancel each other. Is easy to form.
There is a problem that the second-order nonlinear optical effect which is important in application is not exhibited in such a centrosymmetric crystal.
In order to break the central symmetry, which is a problem in expressing nonlinearity in the crystalline state, a substituent having hydrogen bonding ability or an optically active substituent having an asymmetric carbon is converted to an organic compound having a π-electron conjugated system. The idea is to introduce it at the time of molecular design.

Generally, the properties required as a material for a nonlinear optical element include the magnitude of optical nonlinearity, light transmission, laser damage resistance, crystallinity, phase matching, workability, and mechanical properties. Strength, hygroscopicity and the like.

It has been extremely difficult to select a material that satisfies the above-mentioned various properties required for practical use from conventionally known materials for organic nonlinear optical elements.

The present invention has been made in view of the above situation in the related art.

Accordingly, an object of the present invention is to improve the problems in the conventionally known nonlinear optical element materials, to have a large nonlinear optical effect, and to improve the storage stability and workability of a practical organic nonlinear optical element. It is to provide materials.

Means for Solving the Problems The present inventor has found that, even in a compound system in which the dipole moment of a molecule is large and which tends to form central symmetry during crystallization, by introducing an appropriate substituent into the molecule, it is possible to obtain particularly 2 The inventors have found that the following organic nonlinear optical material having a large nonlinear optical effect can be obtained, and have completed the present invention.

The above object of the present invention is achieved by a novel squarylium derivative represented by the following general formula (I).

(Wherein, X represents a hydrogen atom, a methyl group, an ethyl group or a methoxy group, and R is Represents C ^* means an asymmetric carbon atom. The cyclobutenedione ring contained in the squarylium derivative represented by the above general formula (I) of the present invention has a strong electron-withdrawing property comparable to a nitro group, as can be seen from the maximum absorption wavelength shown in Examples described later. And a long π-electron conjugated system. For this reason, the entire molecule can easily take a structure that is electronically greatly polarized, which causes high nonlinearity. In addition, in the squarylium derivative represented by the above general formula (I), when a substituent having an asymmetric carbon atom is introduced, even if the dipole moment of the molecule itself is large, the bulk structure can be reduced. By controlling the orientation of the molecules in and by breaking the central symmetry, a large optical non-linearity will be developed.

The squarylium derivative represented by the above general formula (I) of the present invention can be easily synthesized with high yield by the following reaction formula.

(Wherein, Y represents a chlorine atom, a bromine atom, a methoxy group or an ethoxy group, and X and R have the same meanings as defined above, respectively.) That is, the square rillyl derivative represented by the general formula (II) Acetone, tetrahydrofuran, methanol,
Suspended or dissolved in a solvent such as ethanol, and then, in the obtained suspension or solution, an amino compound represented by the general formula (III) in an amount equal to or more than the equivalent of the squarylium derivative was gradually added with stirring. And react. The reaction usually proceeds promptly, but can be heated if necessary. If the product precipitates with the progress of the reaction, the product may be filtered, and if the product does not precipitate, it may be concentrated or precipitated by adding an appropriate poor solvent. The obtained crystals are recrystallized with a solvent such as alcohol or acetone, if necessary, or purified by sublimation.

Instead of the amino compound represented by the general formula (III), an acid addition salt thereof, for example, a hydrochloride, a bromate, a p-toluenesulfonate, or the like is used as a raw material, and triethylamine, N-methylmorpholine, or the like is used. In the presence of a basic compound, the squarylium derivative represented by the general formula (II) can be reacted in the same manner as described above.

The squarylium derivative represented by the general formula (II) can be obtained, for example, by adding a dimethylaniline compound and dichlorocyclobutenedione to a Friedel-Crafts solvent (eg, carbon disulfide, nitrobenzene, methylene chloride, etc.) in the presence of aluminum chloride. By mixing and stirring to obtain a chlorocyclobutenedione derivative, or by reacting a dialkoxycyclobutenedione with a dimethylaniline compound together with a trialkyloxonium salt and a halogenated solvent to obtain an alkoxycyclobutenedione derivative. And the like.

Examples Hereinafter, the present invention will be described with reference to examples.

Example 1 4- (4'-dimethylaminophenyl) -3- (2'-
Synthesis of hydroxypropylamino) -cyclobutene-1,2-dione 2 g (8.4 mmol) of a compound represented by the following structural formula (II-1)
l) To 100 ml of acetone solution, 2 g of S-(+)-1-amino-2-propanol was added, and the mixture was heated and stirred for about 2 hours. Yellow crystals precipitated in the reaction solution. After allowing the reaction solution to stand, yellow crystals are collected to give 4- (4 ′) represented by the following structural formula (I-1).
-Dimethylaminophenyl) -3- (2'-hydroxypropylamino) -cyclobutene-1,2-dione 2.1 g
(7.7 mmol) were obtained as yellow crystals. Yield 92%.

Melting point: 245 ° C Maximum absorption wavelength λmax: 400 nm (in CH ₂ Cl ₂ ) Elemental analysis C H N Calculated value 65.67 6.61 10.21 Measured value 65.56 6.72 10.16 Example 2 4- (4'-dimethylaminophenyl) -3- (2'-
Synthesis of hydroxyethylamino) -cyclobutene-1,2-dione 0.5 g (2.0 mmol) of a compound represented by the following structural formula (II-2)
l) 21 ml of ethanolamine was added, and the mixture was stirred with heating for about 2 hours. After the completion of the reaction, the reaction product was poured into about 60 ml of water to precipitate a reaction product as yellow crystals. By collecting the yellow crystals, 4- (4′-) represented by the following structural formula (I-2) is obtained.
Dimethylaminophenyl) -3- (2'-hydroxyethylamino) -cyclobutene-1,2-dione 0.32 g (1.2 m
mol) were obtained as yellow crystals. Yield 60%.

Melting point 240 ° C Maximum absorption wavelength λmax: 401 nm (in CHCl ₃ ) Elemental analysis C H N Calculated value 64.61 6.20 10.76 Measured value 64.58 6.12 10.58 Example 3 4- (4'-dimethylaminophenyl) -3- (1'-
Methoxycarbonylethylamino) -cyclobutene-1,
Synthesis of 2-dione 0.7 g (5 mmol) of L-alanine methyl ester hydrochloride
And 20 g of an acetone solution containing 0.6 g (5.6 mmol) of triethylamine and 1.0 g of the compound represented by the above structural formula (II-1)
20 ml of an acetone solution of (4.2 mmol) was gradually added and reacted. After reacting for about 2 hours, water was added. By collecting the precipitated yellow microcrystals, the following structural formula (I-
4- (4'-dimethylaminophenyl) represented by 3)
0.66 g (2.2 mmol) of -3- (1'-methoxycarbonylethylamino) -cyclobutene-1,2-dione was obtained. Yield 52%.

Melting point: 217 ° C Maximum absorption wavelength λmax: 401 nm (in CH ₂ Cl ₂ ) Elemental analysis C N calculated 63.56 6.00 9.27 measured 63.32 5.82 9.35 Examples 4 to 33 Example 1 was repeated except that the squarylium derivative described in the column of the general formula (II) in Table 1 and the amino compound described in the column of the general formula (III) were used as raw materials. The target product described in the column of general formula (I) in Table 1 was synthesized in the same manner as described.

About the obtained product, the elemental analysis value, the maximum absorption wavelength λmax, and the melting point were measured. Table 2 shows the results.

Application Example The compound represented by the structural formula (I-1) described in Example 1 was charged into a sample of powder filled in a glass cell with N.
When irradiated with a d: YAG laser (wavelength 1.064 μm, output 180 mJ / pulse), 532 nm green scattered light due to SHG was generated. The strength was measured to be about 70 times the value measured for the urea powder under the same conditions.

Effect of the Invention The squarylium derivative represented by the above general formula of the present invention is a novel compound, exhibits high nonlinearity, and is a substance excellent in heat resistance, light resistance, storage stability and workability. Therefore, it can be used for manufacturing a nonlinear optical element, for example, an optical wavelength conversion element, an optical shutter, a high-speed optical switching element, an optical logic gate, an optical transistor, and the like.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI G02F 1/35 504 G02F 1/35 504 C07M 7:00 (58) Field surveyed (Int.Cl. ⁶ , DB name) C07C 225/22 C07C 229/10 C07C 221/00 C07C 227/18 REGISTRY (STN) CA (STN) CAOLD (STN)

Claims (3)

(57) [Claims] 1. A squarylium derivative represented by the following general formula (I). (Wherein, X represents a hydrogen atom, a methyl group, an ethyl group or a methoxy group, and R is Represents C ^* means an asymmetric carbon atom. ) 2. The following general formula (II) (Wherein X represents a hydrogen atom, a methyl group, an ethyl group or a methoxy group, and Y represents a chlorine atom, a bromine atom, a methoxy group or an ethoxy group) and a squarylium derivative represented by the following general formula (II)
I) NH ₂ R (III) (where R is —CH ₂ CH ₂ OH, Represents C ^* means an asymmetric carbon atom. The method for producing a squarylium derivative according to claim 1, wherein an amino compound represented by the following formula is reacted. 3. The method according to claim 1, wherein the squarylium derivative represented by the general formula (II) is reacted with an acid addition salt of an amino compound represented by the general formula (III) in the presence of a basic compound. The method for producing a squarylium derivative according to claim 1.