JPH0545685A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain an org. nonlinear optical material having large function to produce the second harmonic waves by introducing an amide group into a tolane compd. CONSTITUTION:This material is expressed by chemical formula 3 having a large nonlinear optical effect regardless to the kind of its alkoxyl group. In formula, R1 is an alkyl group of 1-12 carbon number, R2 is an alkyl group of 2-12 carbon number, alkyl group containing cycloparaffin ring, or halogen alkyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic nonlinear optical material having a large second harmonic generation capability.

[0002]

Non-linear optical materials are used for the generation of second harmonics,
Optical wavelength conversion such as second harmonic generation, optical parametric amplification,
It is attracting attention as a useful material for optical switches and optical memories that utilize the optical bistable phenomenon. Conventionally, inorganic ferroelectric materials such as LiNbO ₃ and KH ₂ P have been used as materials for generating second harmonics.
O ₄ etc. have been used. However, in recent years, a non-linear optical material of an organic compound has been attracting attention as a material having a performance superior to that of an inorganic material. Organic non-linear optical materials are characterized by large non-linear optical constants, high-speed response, diversity in molecular design, etc., as compared with conventional inorganic non-linear optical materials. 2-Methyl-4-nitroaniline (MNA), which is a typical organic nonlinear optical material, has LiN as a second-order nonlinear optical characteristic.
Since it has a figure-of-merit of 2000 times that of bO ₃ , a wide range of organic materials have been searched for.

[0003]

An organic non-linear optical material having a large non-linear optical effect, which has been conventionally known, has an electron-donating alkoxyl group and an electron-withdrawing nitro group in each of two benzene rings of a tolan skeleton. There is a 4-alkoxy-4'-nitrotolan compound introduced (Japanese Patent Laid-Open No. Sho 6-86).
2-136601). However, the compounds of this system often have different crystal forms depending on the type of solvent used for crystallization, and may show non-linear optical effects or non-linear optical effects at all, and depending on the type of alkyl group. It has a drawback that it may exhibit a non-linear optical effect and may not exhibit a non-linear optical effect at all. This is because the 4-alkoxy-4'-nitrotolan compound has an electron-donating alkoxyl group and an electron-accepting nitro group at both ends of a long and slender rod-shaped molecule, and thus has a large dipole moment and is dipolar in the crystalline state. It is considered that the molecules are oriented antiparallel to each other due to the child-dipole interaction and the second-order nonlinear optical effect disappears.

[0004]

It is expected that amide groups can orient molecules by large intermolecular hydrogen bonding interactions that exceed intermolecular dipole-dipole interactions.
Therefore, in order to solve the above-mentioned drawbacks of the tolan-based nonlinear optical compound, in the present invention, an amide group is further introduced to the tolan-based nonlinear optical compound having an electron-donating alkoxyl group and an electron-accepting nitro group as a substituent. .. That is, the following general formula (2)

[0005]

[Chemical 2]

(However, R ₁ represents an alkyl group having 1 to 12 carbon atoms, R ₂ represents an alkyl group having 2 to 12 carbon atoms, an alkyl group containing a cycloparaffin ring, or a halogenated alkyl group. It was found that the tolan compound represented by (1) shows a large nonlinear optical effect. Furthermore, the alkyl group R ₁ of the alkoxyl group is n-
A compound in which an amide group alkyl group R ₂ is specified as an n-propyl group as a hexyl group exhibits a large non-linear optical effect and good crystallinity, and a large single crystal can be easily grown.

[0007]

The present invention is characterized by introducing a hydrogen-bonding amide group into the benzene ring of the tolan skeleton. Since this amide group controls the direction of intermolecular interaction, a large nonlinear optical effect is stably exhibited.

[0008]

【Example】

[Example 1] 4-hydroxybenzaldehyde and n-bromide
4-n-hexyloxybenzaldehyde was synthesized from -hexyl and then converted to 4-n-hexyloxycinnamic acid by condensation with malonic acid in pyridine. This was brominated and then debranched from HBr to synthesize 4-n-hexyloxyphenylacetylene. 4-Nitro-2-butyrylamino-1-bromobenzene was synthesized from 2-bromo-5-nitroaniline and n-butyryl chloride. 4-n
-Hexyloxyphenylacetylene and 4-nitro-2-
By coupling butyrylamino-1-bromobenzene with triethylamine in the presence of catalytic amounts of cuprous iodide, bis (triphenylphosphine) palladium (II) dichloride, and triphenylphosphine, pale yellow crystalline 4 -N-hexyloxy-2'-butyrylamino-4'-nitrotran (referred to as compound 1) was obtained. The melting point was 122-122.5 degrees Celsius. The infrared absorption spectrum of Compound 1 is shown in FIG.

Compound 1 was recrystallized from acetonitrile to give a pale yellow crystal, which was then ground with a mortar to select a powder having a particle size of 75 to 120 μm. This powder was molded to a thickness of 0.5 mm and Nd: YAG laser (beam diameter 1.
0 mm, wavelength 1.06 μm, peak output 100 kW, 3
0 Hz). The intensity of the generated second harmonic was measured with a photomultiplier tube. For comparison, the intensity of the second harmonic from the urea crystal powder (particle size 75 to 120 μm) was similarly measured. The intensity of the second harmonic from the powder of Compound 1 was 34 times the intensity of the second harmonic of urea. The intensity of the second harmonic from the powder of pale yellow crystals obtained by recrystallizing Compound 1 from ethanol was 21 times that of urea. The intensity of the second harmonic from the powder of pale yellow crystals obtained by recrystallizing Compound 1 from benzene was 20 times that of urea. The intensity of the second harmonic from the pale yellow crystalline powder obtained by recrystallizing Compound 1 from methylcyclohexane was 24 times that of urea.

3.2 g of 4-n-hexyloxy-2'-
Butyrylamino-4'-nitrotran (Compound 1) 1
It was dissolved in 00 cc of ethylene glycol monoethyl ether at 70 degrees Celsius, left for 1 hour in a constant temperature bath of 60 degrees Celsius, and then cooled at a rate of 0.1 ° C./hour. After 10 days, it had a size of 3 × 3 × 60 mm. Sasa crystals have grown. The intensity of the second harmonic from the powder obtained by crushing this crystal is 2
It was 1 time.

Example 2 4-Nitro-2-propionylamino-1-bromobenzene was synthesized from 2-bromo-5-nitroaniline and propionyl chloride. Four
-N-hexyloxyphenylacetylene and 4-nitro-
Light-yellow crystalline 4-n-hexyloxy-2′-propionylamino-4′-nitrotran (referred to as compound 2) was obtained from 2-propionylamino-1-bromobenzene in the same manner as in Example 1. Melting point, 145-147 degrees Celsius
It was degree. The intensity of the second harmonic wave from the crystal powder obtained by recrystallizing Compound 2 from benzene was 17 times that of urea.

[Embodiment 3] 4-
Methoxyphenylacetylene was synthesized. In the same manner as in Example 1, 4-methoxy-2′-propionylamino-4′-nitrotolan (compound 3) was prepared from 4-methoxyphenylacetylene and 4-nitro-2-propionylamino-1-bromobenzene in the same manner as in Example 1. I got). The melting point was 186-187 degrees Celsius. The intensity of the second harmonic wave from the crystal powder obtained by recrystallizing Compound 3 from acetonitrile was 25 times that of urea.

Example 4 In the same manner as in Example 1, 4-methoxyphenylacetylene and 4-nitro-2-butyrylamino-1-bromobenzene were used as 4-yellow crystalline crystals.
Methoxy-2'-butyrylamino-4'-nitrotolan (referred to as compound 4) was obtained. Melting point, 174-175 degrees Celsius
It was degree. The intensity of the second harmonic from the crystal powder obtained by recrystallizing Compound 4 from ethanol was 28 times that of urea. The intensity of the second harmonic from the crystal powder obtained by recrystallizing Compound 4 from acetonitrile was 27 times that of urea.
The intensity of the second harmonic from the crystal powder obtained by recrystallizing Compound 4 from methylcyclohexane was 20 times that of urea. The melt obtained by heating the crystal powder of compound 4 above the melting point on the glass substrate was cooled to crystallize, and then the powder obtained by pulverizing this melt had a second harmonic intensity 23 times higher than that of urea. It was

Example 5 A pale yellow crystal of 4-methoxy-2′- was prepared from 4-methoxyphenylacetylene and 4-nitro-2-isobutyrylamino-1-bromobenzene in the same manner as in Example 1. Obtained isobutyrylamino-4′-nitrotran (referred to as compound 5). Melting point, 203 degrees Celsius
It was -204 degrees. The second harmonic intensity from the crystal powder obtained by recrystallizing Compound 5 from ethanol was 21
It was double.

Example 6 From 4-methoxyphenylacetylene and 4-nitro-2-undecanoylamino-1-bromobenzene in the same manner as in Example 1, a pale yellow crystalline 4-methoxy-2'- was obtained. Undecanoylamino-4'-
Nitrotran (called compound 6) was obtained. Melting point, 1 degree Celsius
It was 50-152 degrees. The intensity of the second harmonic from the crystal powder obtained by recrystallizing Compound 6 from ethanol was 21 times that of urea. The second harmonic intensity from the crystal powder obtained by recrystallizing Compound 6 from acetonitrile was 23
It was double. The melt obtained by heating the crystal powder of the compound 6 above the melting point on the glass substrate was cooled to crystallize, and then the powder obtained by pulverizing this melt had a second harmonic intensity 17 times that of urea. It was

Example 7 4-Methoxyphenylacetylene and 4-nitro-2-methacryloylamino-1-
4-methoxy-2'-methacryloylamino-forms a pale yellow crystal from bromobenzene in the same manner as in Example 1.
4'-nitrotran (referred to as compound 7) was obtained. Melting point,
It was 163-164 degrees Celsius. The intensity of the second harmonic wave from the crystal powder obtained by recrystallizing Compound 7 from ethanol was 11 times that of urea.

[Example 8] A pale yellow crystal of 4-methoxy-2'-cyclohexyl was prepared from 4-methoxyphenylacetylene and 4-nitro-2-cyclohexylcarbonylamino-1-bromobenzene in the same manner as in Example 1. Carbonylamino-4'-nitrotran (referred to as compound 8)
Got The melting point was 190-192 degrees Celsius. The intensity of the second harmonic from the crystal powder obtained by recrystallizing Compound 8 from benzene was 12 times that of urea.

Example 9 4-Methoxyphenylacetylene and 4-nitro-2- (4-chlorobutyrylamino)
Light-yellow crystalline 4-methoxy-2 ′-(4-chlorobutyryl) amino-4′-nitrotran (referred to as compound 9) was obtained from -1-bromobenzene in the same manner as in Example 1. Melting point was 178-180 degrees Celsius. Compound 9
From the crystalline powder obtained by recrystallizing
The intensity of the next harmonic was 6.7 times that of urea.

[Example 10] 4-methoxyphenylacetylene and 4-nitro-2- (4-methoxycarbonylpropionylamino) -1-bromobenzene were used in the same manner as in Example 1 to give 4-methoxy of pale yellow crystals. -2'-
(4-Methoxycarbonylpropionyl) amino-4 ′
-Nitrotran (called compound 10) was obtained. Melting point, 140-141 degrees Celsius. The second harmonic intensity from the crystal powder obtained by recrystallizing Compound 10 from acetonitrile was 26 times that of urea.

[0020]

As described above, 4-alkoxy-2'-acylamino-4'-nitrotran having a hydrogen-bonding amide group as a substituent is a compound having a large nonlinear optical effect regardless of the type of the alkoxyl group. Therefore, it is suitable as a material for a nonlinear optical device, especially for generating a second harmonic.

[Brief description of drawings]

FIG. 1 shows an infrared absorption spectrum of 4-n-hexyloxy-2′-butyrylamino-4′-nitrotran, which is one of the examples of the present invention.

Front page continuation (72) Inventor Masafumi Kiguchi 2520 Akanuma, Hatoyama-cho, Hiki-gun, Saitama Inside Hitachi Research Laboratories, Inc. In the laboratory

Claims (2)

[Claims] 1. The following general formula (1): (However, R ₁ represents an alkyl group having 1 to 12 carbon atoms, R ₂ represents an alkyl group having 2 to 12 carbon atoms,
Or an alkyl group containing a cycloparaffin ring, or a halogenated alkyl group). 2. The organic nonlinear optical material according to claim 1, wherein R ₁ is an n-hexyl group and R ₂ is an n-propyl group.