JPH04199135A - Nonlinear optical element material - Google Patents

Abstract

PURPOSE:To obtain a practical org. nonlinear optical element material having a large nonlinear optical effect and improved storage stability and workability by using a compd. expressed by a specified formula. CONSTITUTION:The compd. used is expressed by formula I, wherein X is an amino acid deriv. having asymmetric carbon, Yn is n electron-donating substd. groups coupled with phenyl group, and n is 1 - 5. This compd. has strong electron affinity of cyclobutendion ring comparable to a nitro group and a long pi-electron conjugate, so that the whole molecule has a largely polarized structure and high optical nonlinearity. Thus, the obtd. org. nonlinear optical element material is a practical material and has large nonlinear optical effect and improved storage stability and workability.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a material for nonlinear optical elements used in optical communication, optical information processing, etc. Specifically, the present invention relates to a material for a nonlinear optical element, in which a conjugated π-electron system having an electron-donating substituent contains a cyclobutenedione ring as an electron-withdrawing substituent.

(Prior Art) Nonlinear optical elements play an important role in the fields of optical communication and optical information processing. Materials for nonlinear optical elements can be used for optical mixing, which generates the sum and difference frequencies of two types of incident light with different frequencies, optical parametric, which generates two types of light with different frequencies, and electrical and optical mixing of the original medium. The Pockels effect and Kerr effect that change the refractive index, or the second harmonic of the incident light (S
It has an extremely important effect on optical signal processing, such as exchanging to third harmonic (THG) or third harmonic (THG).

Conventionally, KDP (KH2
Although inorganic crystals such as PO4) and lithium niobate (LiNb03) were known, no material sufficient to meet the requirements was found.

Organic nonlinear optical materials have recently attracted attention as new materials for optical elements in the field of optoelectronics, and research on them has become more active year by year.

In particular, many studies have been conducted on organic compounds having a π-electron conjugated system to search for materials because of their high performance as a single molecule and high-speed response. In general, crystals of organic compounds have a SHG coefficient of 10 to 10% compared to crystals of inorganic compounds.
It is known that it is about 100 times larger, its photoresponse speed is about 1000 times faster, and its threshold for photodamage is also larger.

Conventionally known organic nonlinear optical materials include 2-methyl-4-nitroaniline, m-nitroaniline, and N-
(4-nitrophenyl)-L-prolinol, 2-acetylamino-4-nitro-N, N-dimethylaniline, 4-dimethylamine-4'-nitrostilbene, 4?
-dimethylamino-N-methyl-4-stilbazolium methyl sulfate and 4'-methylbenzylidene-4
- Examples include nitroaniline. The optical nonlinearity of organic compounds having these π-electron conjugated systems is due to the interaction between laser light as an electromagnetic wave and π-electrons of the organic compound, and this interaction causes electron attraction to the π-electron conjugated system. sex,
It can be made even larger by introducing an electron-donating substituent.

However, in such organic compound systems, the dipole moment generally increases, and the dipole-dipole interaction during crystallization becomes stronger, resulting in a centrally symmetrical crystal in which the dipoles of two adjacent molecules cancel each other out. It becomes easier to form. Another problem is that the second-order nonlinear optical effect, which is important in applications, does not occur in such centrosymmetric crystals.

Therefore, in order to break the central symmetry, which is a problem in expressing optical nonlinearity in the crystalline state, we designed the molecule to be an electronically conjugated system with a substituent that has hydrogen bonding ability and an optically active substituent that has an asymmetric carbon atom. Efforts have been made to introduce it from time to time. The present inventor has disclosed in Japanese Patent Application No. 1-248108 a specific example of a material that exhibits a larger nonlinear effect than conventional materials by introducing such an optically active substituent having an asymmetric carbon atom into a π-electron conjugated system. However, even greater improvements in nonlinear effects are desired.

(Problems to be Solved by the Invention) Generally, the characteristics required for a material for a nonlinear optical element are the magnitude of optical nonlinearity, light transmittance, laser damage resistance, crystallinity, phase matching, and processability. , mechanical strength, hygroscopicity and hardness.

Among the conventionally known materials for nonlinear optical elements,
It has been difficult to select a material for nonlinear optical elements that satisfies the various practical requirements as described above.

The present invention was made with the aim of improving the above-mentioned problems of conventionally known materials for nonlinear optical elements, and its purpose is to improve large nonlinear optical effects, storage stability, and processability. The object of the present invention is to provide a practical material for organic nonlinear optical elements.

Another object of the present invention is to provide a material for an organic nonlinear optical element that has a large second-order nonlinear optical effect.

(Means for Solving the Problems 9) The present inventor has proposed that the present inventors introduce appropriate substituents into molecules even in compound systems that have a large dipole moment in the ground state of the molecule and are likely to form central symmetry during crystallization. By this,
In particular, it was discovered that a material for organic nonlinear optical elements having a large second-order nonlinear optical effect can be obtained, and the present invention was completed. That is, the above object of the present invention is achieved by the following general formula (
This is achieved by using the compound shown in I).

The material for nonlinear optical elements of the present invention comprises a compound represented by the following general formula (I).

(In the formula, Indicates a number. In the formula, R1 to R5 represent a substituted or unsubstituted alkyl group, and R1 and R2 may be the same or different from each other.) R4S-(Iv) HO(V) R5-(Vf) In the above general formula (I), the substituent X is an organic compound residue in which an amino acid derivative having an asymmetric carbon is bonded to a cyclobutenedione ring via a nitrogen atom, and specifically, 2-chlorocyclobutenedione ring or 2-alkoxycyclobutenedione ring.

In order to control the orientation of molecules in a bulk state or a thin film state, these substituents It is important to include such things as

In this case, even if the dipole moment of the molecule itself is large, large optical nonlinearity can be developed by controlling the orientation of the molecule in the bulk or thin film structure and breaking the central symmetry.

Specific examples of the compound represented by the above general formula (I) in the present invention are illustrated below.

1-(4'-N, N-diethylaminophenyl)-2
-(2'-Hydroxypropylamino)-cyclobutene-3,4-dione, [Compound (I-1)] 1-(4'-N, N-diethylaminophenyl)-2
-(1'-Hydroxymethyl-2'-phenylethylamino)-cyclobutene-34-dione, [Compound (I-2)] 1-(4'-N-methyl, N-ethylaminophenyl doxymethyl-2 '-Phenylethylamino)-cyclobutene-3,4-dione, [Compound (I-3)] 1, (4'-N-methyl, N-methoxyethylaminophenyl)-2-(2'-hydroxypropylamino) , cyclobutene-34-dione, [Compound (R4)] 1-(4'-methoxyphenyl)-2-(2-hydroxypropylamino)-cyclobutene-3,4-dione,
[Compound (I-5)] 1-(4-methoxyphenyl)-2-(1'-hydroxymethylpropylamino)-cyclobutene-3,4-dione, [Compound (I-6)] 1-(4' -Methylthiophenyl-2-phenylethylaminone, [Compound (R7)] 1-(3',4'-dimethoxyphenyl)-2-(2'
-hydroxymethylethylamino)-cyclobutene-3
,4-dione, [Compound (I-8)] 1-(3',4'-dimethoxyphenyl)-2-(2'
-hydroxypropylamine)-cyclobutene-3,4
-dione, [compound (I-9)] 1-(3',4'-dimethoxyphenyl)-2-(1'
-Hydroxymethylpropylamino)-cyclobutene-
3,4-dione, [Compound (I-10)] 1-(3′,4”-dimethoxyphenyl)-2-(1-
Hydroxymethyl-2'-phenylethylamino)-cyclobutene-3,4-dione, [Compound (I-11)] The compound represented by the above general formula (1) in the present invention is:
It can be easily synthesized with good yield according to either reaction formula (A) or (B) shown in FIG.

First, as a first-stage reaction, in the case of reaction formula (A), for example, at a temperature of about 5 to 50°C, formula (■)
compounds, such as about 20-50 mmol of diethylaniline
l and dichlorocyclobutenedione of formula (■) about 20 to 1
The reaction is carried out by mixing and stirring 50 mmol in about 100 to 1000 ml of a Friedelkraff solvent (eg, carbon disulfide, nitrobenzene, methylene chloride, etc.). This reaction is preferably carried out using a catalyst, e.g.
Performed in the presence of 0 mmol aluminum chloride.

The reaction is continued for about 2-8 hours, after which the Friedelkraff solvent is removed to obtain the chlorocyclobutenedione derivative of formula (IX) as an intermediate.

In addition, in the case of reaction formula (B), about 20 to 100 mmol of jetoxycyclobutenedione of formula (X),
Triethyloxonium fluoroborate about 50-20
0 mmol, halogenated solvent, e.g. methylene chloride approx.
0 to 250 ml and about 20 to 200 mmol of a compound of formula (■), for example diethylaniline, at room temperature. After stirring for 6 to 12 hours, the solvent is removed under reduced pressure to obtain an alkoxycyclobutenedione derivative of formula (XI) as an intermediate.

Then, as a second step reaction, the compound represented by the general formula (IX) or (XI) obtained as described above is
React with an amino acid derivative having an asymmetric carbon. That is, a compound represented by general formula (IX) or (XI),
Suspend or dissolve in a solvent such as acetone, tetrahydrofuran, methanol, or ethanol. Next, to this suspension or solution, an equivalent or more amount of the above-mentioned asymmetric carbon-containing amino acid derivative is gradually added to the compound represented by the general formula (IX) or (XI) while stirring, and allowed to react. . The reaction usually proceeds quickly, but it is possible to heat the reaction if necessary. If the product precipitates as the reaction progresses, it is filtered, and if the product does not precipitate, it is concentrated or a poor solvent is added to precipitate it. The obtained compound represented by general formula (I), if necessary,
It is purified by recrystallization with a solvent such as alcohol or acetone, or by sublimation.

Specific examples of amino acid derivatives having an asymmetric carbon into which a substituent X can be introduced into general formula (1) in the present invention are:
S-(+)-2-amino-1-propanol, R-(-
)-1-amino-2-propatool, R-(-)-2-
Amino-1-butanol, D-phenylalaninol,
L-prolinol, L-leucinol, L-methioninol, L-valinol, L-alanine-t-butyl ester, L-proline-t-butyl ester, L-alanine methyl ester, L-proline methyl ester, L-
Valine methyl ester, L-isoleucine methyl ester, L-leucine methyl ester, L-alanine ethyl ester, L-phenylalanine methyl ester, L-
Examples include amino acid derivatives such as proline benzyl ester, L-tyrosine ethyl ester, L-noradrenaline, L-methionine ethyl ester, and optical isomers thereof.

Next, a synthesis example will be shown for an example of the compound represented by the above general formula (I).

(Synthesis example) 1-(4'-N,N-diethylaminophenyl)-2-
(2'-hydroxyproramino)cyclobutene-3,
4-dione [Exemplary compound (synthesis of January 2013) 1-(4'-diethylaminophenyl)-2-chlorocyclobutene-3,4-dione 0.8 g (3,0 mmol
) in 15 ml of acetone, R-
Add 1 ml of (-)-1-amino-2-propatool,
React for about 2 hours while stirring. The product precipitated during the reaction process was filtered, and 0.42 g of yellow microcrystals (1.4 m
mol) (yield 47%).

Melting point: 226°C Maximum absorption wavelength: 406 nm (in CH2CI2) Elemental analysis CHN Calculated value 67.52 7.34 9.27 Measured value 67.63 7.22 9.15 Others represented by the above general formula (I) The compound can also be synthesized in the same manner as in the above synthesis example.

The compound represented by the above general formula (1) in the present invention is:
Used as a constituent material of nonlinear optical elements. Examples of nonlinear optical elements include optical wavelength conversion elements, optical shutters, high-speed optical switching elements, optical logic gates, and optical transistors.

(Function) The compound represented by the above general formula (1) in the present invention is:
The cyclobutenedione ring contained therein has a strong electron-withdrawing property comparable to that of a nitro group, and also has a long π-electron conjugated system, which makes it easier for the entire molecule to assume a highly electrically polarized structure, resulting in high It has optical nonlinearity.

In addition, since an amino acid derivative having an asymmetric carbon atom is introduced as X in the above general formula (I), even if it includes a -electron conjugated system that has a large dipole moment in the ground state. , it has high optical nonlinearity.

Furthermore, the compound represented by the above general formula (1) has heat resistance,
It has excellent light resistance, transparency, stability, and processability, so it can be used as a material for nonlinear optical elements.

(Example 1) Powder of L-(4'-N, N-diethylaminophenylxypropylamino)-cyclobutene-3,4o dione (the exemplified compound niυ shown below) was filled in a glass cell, and a Nd:YAG laser was applied to the glass cell. (Wavelength 1, Q64μm, output 180
mJ/pulse), 532
nm green scattered light was generated. When its strength was measured, it was 16 times the value measured for urea powder under similar conditions.

Note that FIG. 2 is a block diagram of an optical system used to evaluate the SHG intensity of the above sample using the powder method. In the figure, l
li, tNd: YAG laser, 12 is a powder sample filled in a glass cell, 13 is a lens, 14 is a filter, 15 is a monochromator, 16 is a photomultiplier tube, 1
Reference numeral 7 is a box car inching grator, and 18 is an oscilloscope. Wavelength 1.0 from Nd:YAG laser-11
The sample 12 is irradiated with 64 μm light, and the green scattered light with a wavelength of 532 nm generated from the sample is sent to the photomultiplier tube 16.
The SHG intensity was measured using a .

(Example 2) The following exemplary compounds (C2), (I-3), (I-4), (
Knee 5), (I-6), (Knee 7), (I-8), (I
Table 1 shows the results of measuring the SHG intensity of the samples in the same manner as in Example 1 using -9), (Knee 10), and (I-11).

The structural formulas of the exemplary compounds are as follows.

(In the formula, *C means an asymmetric carbon atom) Exemplary compound (
2) C6H5CH2C*HCH20H] (Effects of the invention) The material for nonlinear optical elements of the present invention has high SHG strength, excellent heat resistance, light resistance, and transparency, and has good stability and processability. Crystals are easily obtained. Therefore, the material for nonlinear optical elements of the present invention is very excellent as a constituent material for, for example, optical wavelength conversion elements, optical shutters, high-speed optical switching elements, optical logic gates, optical transistors, and the like.

[Brief explanation of the drawing]

FIG. 1 shows an example of a chemical formula for synthesizing the nonlinear optical material of the present invention. FIG. 2 is a block diagram of an optical system used to evaluate SHG intensity using the powder method. 11...Nd:YAG laser-, 12...sample, 14...filter, 15...monochromator-
116...Photomultiplier tube, 17...Box car inching grater, 18...Oscilloscope. Patent applicant: Fuji Xerox Co., Ltd. Agent: 1st grade) Akira Hanzuki Fujio (■) (VI)
(IX)υ (I) (■) (x)
(XI) Figure 1

Claims (2)

[Claims] (1) A material for nonlinear optical elements comprising a compound represented by the following general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, X consists of an amino acid derivative having an asymmetric carbon, and Yn is n atoms bonded to a phenyl group (n indicates a number from 1 to 5) (indicates an electron-donating substituent) (2) In the general formula (I) above, Y is an electron-donating substituent represented by any of the following chemical formulas (II) to (VI);
The material for a nonlinear optical element according to claim 1, which is a combination thereof. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) R_3O-(III) R_4S-(IV) HO-(V) R_5-(VI) (In the formula, R_1 to R_5 represent substituted or unsubstituted alkyl groups. , R_1 and R_2 may be the same or different.)