JPH0197926A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain an org. nonliner optical material which is strong to optical damages, is thermally stable and has an excellent nonliner optical effect by using a compd. having a specific heterocycle as an electron-accepting group. CONSTITUTION:This optical material is formed by using the compd. which has the heterocycle as the electron-accepting group and is expressed by the formula I. In the formula I, X<1>, X<2> respectively denote a chalcogen atom, NH or NR<2>; R<1> denotes an alkyl group or aryl group of 1-6C; R<2> denotes an alkyl group of 1-6C; Ar denotes an electron-donating group. The chalcogen atom is exemplified by oxygen, sulfur, selenium, tellurium, and polonium. The org. nonliner optical material which is strong to the optical damages, is thermally stable and has the large nonliner optical constant is thereby obtd.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an organic nonlinear optical material, and more particularly to an organic optical material useful in fields such as optical information processing, optical communication, optical measurement, and optoelectronics. .

[Conventional technology]

In recent years, the coherent and strong optical electric field brought about by the development of lasers has enabled nonlinear optical effects in which the polarization of materials responds nonlinearly to the optical electric field. Substances that exhibit nonlinear optical effects are called nonlinear optical materials, and they produce various effects such as optical harmonic generation, optical rectification, optical mixing, optical parametric amplification, phase conjugate wave generation, and self-focusing effects. It is attracting attention as a material for various applications such as optical computers and optical electronics.

Conventionally, inorganic materials such as K H and P O have been used as nonlinear optical materials, but their nonlinear optical constants are not large enough and their hygroscopic properties limit their use. For example, when used as a harmonic generator for a laser, it was fixed inside a drying box. In contrast, organic substances with large nonlinear optical constants and no hygroscopicity are attracting attention.
Because it is susceptible to photodamage (not very stable thermally), it has not yet been possible to find a product that can be used as a practical product. For example, 2-methyl-4- is the most famous organic nonlinear optical material.
The melting point of nitroaniline (MNA) is 131-3°C.

[Problem that the invention seeks to solve]

The present invention aims to provide an organic nonlinear optical material that is resistant to optical damage, thermally stable, and has a large nonlinear optical constant.

[Means for solving problems]

As a result of intensive research into organic nonlinear optical materials with excellent practicality, the present inventors found that an organic nonlinear optical material consisting of a compound having a specific heterocycle as an electron-accepting group can be suitable for the above purpose. The present invention was completed based on this finding.

That is, the present invention provides an organic nonlinear optical material represented by the following general formula having a heterocycle as an electron-accepting group.

, or NR'', R1 is hydrogen, an alkyl group having 1 to 6 carbon atoms or an aryl group, Rt is an alkyl group having 1 to 6 carbon atoms, and ^r is an electron donating group.] In the above general formula -' Chalcogen atoms include oxygen, sulfur, selenium,
Examples of XI include tellurium and polonium. XI is preferably NH or S. Preferred RI is hydrogen. Poisonous examples of R1 include methyl, phenyl, and naphthyl groups.

Examples of the electron-donating group Ar include CtHs or (where n is an integer of 0 to 4).

The heterocyclic compound of the present invention, as shown in the following formula,
An aldehyde compound having an electron-donating group and rhodania represented by (1) CR'=H, ), creatinine (R' = H, X' = NCH3, X'' -N)
It can be synthesized by a simple one-step reaction of reacting with a compound such as l).

The reaction conditions are not particularly limited, but morpholine/
It can be easily synthesized by reacting in the presence of a solvent such as glycerin or Na0Ac/AczO, preferably at 90 to 130°C for 1 to 6 hours.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by this example.

Synthesis Example 1 2 g (20 mmol) of hydantoin, 3 g (20 mmol) of 4-dimethylaminobenzaldehyde, and 1 ml of morpholine were dissolved in 30 ml of glycerin, and the
heated for an hour. The resulting crystals were separated by filtration and washed successively with water and methanol to obtain 4.1 g (yield: 89%) of yellow crystals.

The melting point of this product is 270°C (decomposition), and the ultraviolet-visible absorption spectrum (dimethyl sulfoxide (DMSO)
The maximum absorption wavelength λ□ of the solvent) is 390 nm, and the molar extinction coefficient ε at that wavelength is 3.3X10'M-'c
m-'). In addition, 'H-NMR (HMDS
/d'-DMSO) results are shown in Table 1.

From these results, it can be seen that the yellow crystals obtained here are a compound represented by the following structural formula.

Table 1 δ value Split Attribution Integral ratio Theoretical ratio 2.90
s a 6.1 66.23
s b 1.0 16.60
d c '2.0 27.35 d
d 2.1 2 Synthesis Example 2 2 g (20 mmol) of hydantoin, 3.5 g (20 mmol) of 4-dimethylaminocinnamaldehyde, 1 mI of morpholine! , dissolved in 30mf of glycerin, 12
Heated at 0°C for 1 hour. The resulting crystals were filtered and washed with water and methanol in that order to give 2.1 g of red crystals (yield 41%).
I got it.

The melting point of this product is 280"C (decomposition), and the ultraviolet-visible absorption spectrum (dimethyl sulfoxide (DMSO)
(solvent) maximum absorption wavelength λ5. The wavelength is 420 nm, and the molar extinction coefficient ε at that wavelength is 4.2X10' M-
'cm-'). In addition, 'H-NMR (HM
DS/d&-DMSO) results are shown in Table 2.

These results show that the red crystals obtained here are compounds represented by the following structural formula.

■ Table 2 δ value Splitting Attribution Integral ratio Theoretical ratio 2.92
s a 6.2 66.23
d b 1.0 1 Synthesis Example 3 2 g (15.0 mmol) of 0-danine, 2.2 g (15.0 mmol) of 4-dimethylaminobenzaldehyde,
2.5 g of sodium acetate (30 mA) and 60 mj of glacial acetic acid
! The mixture was stirred and heated at 100°C for 1 hour. 100m of water
j! was added and stirred at room temperature for 1 hour, and the resulting crystals were filtered and washed with water and methanol in that order to give 3.6 g of red needle-like crystals (
A yield of 90% was obtained.

The melting point of this substance is 288°C, the absorption maximum wavelength λ□8 of the ultraviolet-visible absorption spectrum (dimethyl sulfoxide (DMSO) solvent) is 480 nm, and the molar extinction coefficient ε at that wavelength is 3.8 × 10' M -'cm-'
)Met. Also, 'H-NMR (HMDS/d'
-DMSO) (7) The results are shown in Table 3.

From these results, it can be seen that the red needle crystals obtained here are a compound represented by the following structural formula.

d Table 3 β value Splitting Attribution Integral ratio ・Theoretical ratio 2.95s
a 5.9 66.70d
b 2.0 2 Next, experiments to measure the nonlinear optical effects of the heterocyclic compounds obtained in Synthesis Examples 1 to 3 will be shown in Examples.
(product of permanent dipole moment and second-order nonlinear optical constant)
I will add some explanation about the significance of this.

Generally, when light enters a substance, polarization P occurs due to the electric field of the light, and the relationship is expressed by the following equation 2. Here, χ1 is the susceptibility, χ2 is a second-order nonlinear optical constant, and χ is a third-order nonlinear optical constant.

Although the above relational expression is a relational expression between macroscopic polarization and electric field, it is thought that a similar expression holds true for a single molecule. That is, the microscopic polarization μ of an organic molecule is expressed by the following formula.

μ=μ. +αE+βE"+TE"+... (in the formula, μ.

is a permanent dipole moment, E is an electric field due to light, α is a polarizability, β is a second-order nonlinear optical constant, and T is a third-order nonlinear optical constant. ) Here, the nonlinear optical constants β, T, χ2, and χ3 are related to each other, and it is considered that if one value is large, the other values are also large. Also, β, γ, χ2, χ
The larger the nonlinear optical constant, such as 5, the greater the nonlinear optical effect. Moreover, μ is the permanent dipole moment. There is not much difference between different substances, and most substances are 3 x 10-" -10X 10-" e
It is about su. Therefore, μ of each substance. If β is measured and compared, the difference in the values can be considered to be due to the β value.

Therefore, μ. By measuring the β value, the degree of the nonlinear optical effect of the substance can be immediately determined.

Examples 1-3 μ of the heterocyclic compounds obtained in Synthesis Examples 1 to 3.

The value of β was measured as shown in FIG.

That is, Figure 1 shows the intensity of the second harmonic (SHG) of the sample measured. This is a block diagram of the device used to calculate β. First, a sample (heterocyclic compound obtained in a synthesis example) is dissolved in a DMSO solvent to a concentration of 0.1 to 1.0% by weight. into sample cell 2. Next, an electric field of 3×10'V/m was applied in pulses to this sample cell using a high voltage pulser 8. The light source uses the fundamental wave ω (1,064 μm) of a Q-switched YAG laser 1, and the generated SHG whose polarization plane is incident parallel to the electric field is separated by a spectrometer 3 and collected into a light receiver 4. The peak intensity and interval data of the Maker interference fringes are processed by a computer 7 through an amplifier 5 and an A/D converter 6, and μ. β was calculated. The results are shown in Table 4.

The above experimental method is based on C, C, Teng and
A, F.

Garito, Phys, Rev, B,, 28.6
766 (1983).

Comparative Example 1 In the above example, 2-methyl-4-nitroaniline (MNA) was used instead of the heterocyclic compound obtained in the synthesis example.
The same operation as in the example was performed except that . The results are shown in Table 4.

Table 4 No. Sample compound μ. β(esu) Example 1 Compound of Synthesis Example 1 180 xlO-"Example 2 Compound of Synthesis Example 2 1500 Xl0-"Example 3 Compound of Synthesis Example 3 470 xlO-4'1 ratio 1
51MI NMA 270X10-”
[Effects of the Invention] The heterocyclic compound of the present invention has a large μ. It has a β value and exhibits excellent nonlinear optical effects, especially large SHG effects. It is also resistant to optical damage and thermally stable.

Therefore, the heterocyclic compound of the present invention can be effectively and widely used as devices such as semiconductor laser light sources, arithmetic elements, optical bistable elements, optical modulators, and optical switches in optical communication, optical information processing, optical measurement, etc. .

[Brief explanation of the drawing]

FIG. 1 shows μ of the samples conducted in Examples and Comparative Examples. FIG. 2 is a block diagram of an apparatus used in an experiment to determine a β value. In the figure, l is a Q-switched YAG laser, 2 is a sample cell,
3 is a spectrometer, 4 is a photodetector, 5 is an amplifier, 6 is an A/D converter, 7 is a computer, and 8 is a high voltage pulser.

Claims (1)

[Scope of Claims] 1. An organic nonlinear optical material represented by the following general formula having a heterocycle as an electron-accepting group. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, X^1 and X^2 are chalcogen atoms and N, respectively.
In H or NR^2, R^1 represents hydrogen, an alkyl group or aryl group having 1 to 6 carbon atoms, R^2 represents an alkyl group having 1 to 6 carbon atoms, and Ar represents an electron donating group. ] 2. Electron-donating groups have ▲Mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas, tables, etc.▼, ▲Mathematical formulas, chemical formulas, tables, etc. ▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, or ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, n is 0) -4 integer) The organic nonlinear optical material according to claim 1.