JPH0545683A - Organic nonlinear optical material - Google Patents

Abstract

(57) [Summary] [Structure] General formula (I) An organic nonlinear optical material comprising an organic compound represented by and an organic nonlinear optical element containing the material. [Effect] The organic non-linear optical material has an excellent non-linear optical effect, and is applied to organic non-linear optical elements such as optical wavelength conversion elements and electro-optical elements.

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 used in the field of optical information communication or optical information processing, and a nonlinear optical element such as an optical wavelength conversion element and an electro-optical element using the organic nonlinear optical material.

[0002]

BACKGROUND OF THE INVENTION Organic nonlinear optical materials have recently attracted attention in the fields of optical information communication or optical information processing. The non-linear optical material means a material that exhibits a non-linear optical effect such as converting laser light into light of an arbitrary wavelength or changing the refractive index by applying a voltage. / 2 wavelength light (second
A second-order organic nonlinear optical material having a harmonic oscillation effect was reported in 1983 (ACS Symposium Series 233 (1983)).
Since then, it has been attracting attention as a material showing performance exceeding inorganic materials. Similarly, research is also progressing on a second-order organic nonlinear optical material having an effect of converting laser light into light having a wavelength of ⅓ (third harmonic oscillation).

The secondary organic nonlinear optical material has, for example, an aromatic ring, a donor substituent and an acceptor substituent, and the π electron of the aromatic ring is a molecule formed by the donor substituent and the acceptor substituent. Materials having a structure that is polarized inside are included. It is considered that this type of material has extremely high nonlinear optical responsivity because nonlinear optical properties occur at the π electron site. The third-order nonlinear optical property is π
It has been pointed out that a molecule having a conjugated chain and having a longer π-conjugated chain and a higher conjugation has a higher third-order nonlinear optical property.

Paranitroaniline, which is expected to have a high degree of second-order nonlinear optical response, has a structure in which two adjacent molecules are formed in a single crystal state which is practically indispensable as a nonlinear optical element such as an optical wavelength conversion element or an electro-optical element. The structure is inverted with respect to each other, so that the nonlinear optical property is lost. As described above, the organic non-linear optical material tends to lose its non-linear optical property when adjacent molecules have central symmetry. For this reason,
Organic compounds in which a substituent that eliminates such symmetry between adjacent molecules or a substituent that imparts optical activity are introduced have been synthesized. For example, 2 synthesized in this way
-Methyl-4-nitroaniline has been shown to exhibit high non-linear optical properties.

Organic nonlinear optical materials have higher nonlinear optical properties as the intramolecular polarizability increases, but if the intramolecular polarization is too high, charge transfer occurs and the transparency of the material is lost. At the same time, the wavelength of the second harmonic matches the maximum absorption wavelength λ _max of the organic nonlinear optical material,
The second harmonic cannot be extracted efficiently.

Further, in order to obtain an organic nonlinear optical material,
A nitro group having a high acceptor property and an amino group having a high donor property are introduced at both ends of a linear molecule such as stilbene. However, the material obtained in this manner has problems that adjacent molecules are likely to have central symmetry and that transparency is poor.

In order to solve these problems, methods such as limiting the length of the π-electron conjugated system in the molecule and introducing a hetero atom into the aromatic ring have been tried, but the fundamental method is No solution has been found.

On the other hand, as a third-order organic nonlinear optical material, a material having a long π-conjugated chain such as polydiacetylene has been attracting attention. Unlike the non-linear optical material of the second order, the non-linear optical material of the third order does not lose the non-linear optical property even if the adjacent molecules are center-symmetrical to each other. Therefore, the third-order organic nonlinear optical material has a wider selection range than the second-order nonlinear optical material, and a material having a longer π-conjugated chain can be expected to have better nonlinear optical properties.

However, as the π-conjugated chain becomes longer, the solubility in the solvent decreases and the workability becomes poor. Therefore, if a relatively bulky substituent is added to the side chain of the π-conjugated chain to improve the solubility, there is a problem that the polymerization degree is reduced and the π-conjugated chain length is reduced.

Therefore, in the third-order organic nonlinear optical material, it is desired to develop a material having excellent solubility in a solvent and having a π-conjugated chain of an appropriate length and excellent third-order nonlinear optical property. There is.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a novel organic nonlinear optical material having excellent solubility and processability and exhibiting good nonlinear optical properties, and such an organic nonlinear optical material. It is an object of the present invention to provide a non-linear optical element such as a light wavelength conversion element or an electro-optical element in which an optical material is used.

[0012]

SUMMARY OF THE INVENTION A first organic nonlinear optical material according to the present invention has the following general formula (I).

[0013]

[Chemical 2]

[In the formula, Φ ₁ and Φ ₂ may be the same or different from each other, each is an aromatic ring or a hetero ring, n and m are integers of 0 to 4, and R ₁ and R _{2, which} may be the same or different from each other, are each an electron donating group or an electron accepting group, and R
_{When 1} is directly bonded to Φ ₁ (n = 0), the number of R ₁ may be plural, and R ₂ is directly bonded to Φ ₂ (m
= 0), the number of R ₂ may be plural, R ₃ and R ₄ may be the same or different from each other, and each is a hydrogen atom or an alkyl group, an aryl group, an aralkyl group and It is a group selected from the group consisting of alkyloxy groups. ] It is characterized by comprising an organic compound represented by.

The nonlinear optical element of the present invention is characterized by being made of such an organic nonlinear optical material.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The organic nonlinear optical material according to the present invention will be specifically described below. The organic nonlinear optical material according to the present invention comprises a compound represented by the above formula (I) having a π-conjugated chain.

In the organic compound represented by the formula (I) having these π-conjugated chains, R ₁ is directly bonded to Φ ₁ located at _one end of the molecule when n = 0, and n ≠ 0. In the case of, it is attached to one end of the molecule. Similarly, R ₂ is directly bonded to Φ ₂ located at one end of the molecule when m = 0, and is bonded to one end of the molecule when m ≠ 0.

In any of the above cases, since R ₁ and R ₂ are electron-donating groups or electron-accepting groups, these substituents cause appropriate polarization in the compound molecule represented by the formula (I). , Non-linearity is added.

When R ₁ or R ₂ is an electron accepting group, the Hammett value σ of the electron accepting group is preferably in the range of 0 <σ <0.8.

Specific examples of such an electron accepting group include nitro group, cyano group, trifluoromethyl group, trifluoromethoxy group, trifluoromethylthio group, carbamoyl group, nitroso group, cyanato group, thiocyanato group, Isocyanato group, formyl group, or alkoxycarbonyl group such as methoxycarbonyl and ethoxycarbonyl, halogenated alkoxycarbonyl group, acetyl group, propinoyl group, acyl halide group, sulfo group, sulfino group, sulfeno group, halogen atom and the like. .. Of these, a nitro group is preferable.

When R ₁ or R ₂ is an electron donating group, the electron donating group preferably has a Hammett value σ in the range of 0 ≧ σ ≧ −0.83.

Specific examples of such an electron donating group include aryloxy groups such as dimethylamino group, amino group, hydroxy group and phenoxy group, alkyloxy groups such as methoxy group, methyl group, ethyl group and n. -Propyl group,
linear alkyl group such as n-butyl group, isopropyl group,
sec-butyl group, sec-amyl group and other secondary alkyl groups, te
tert-butyl group, tertiary alkyl group such as tert-amyl group,
Examples thereof include an aryl group and a thioalkyl group. Of these, a methoxy group is preferable.

In the compound represented by the above formula (I), when n = 0 and R ₁ is directly bonded to Φ ₁ , the number of R ₁ may be plural or plural. When R ₁ 's of R are bonded to Φ ₁ , each R ₁ may be the same or different. Similarly, when m = 0 and R ₂ is directly bonded to Φ ₂ , the number of R ₂ may be plural, and when plural R ₂ are bonded to Φ _2. In addition, each R ₂ may be the same as or different from each other.

In the compound represented by the above formula (I), R ₁ is bonded to-(CH = CH) _n -Φ ₁ so as to promote the polarization of-(CH = CH) _n -Φ _1. R ₂ is preferably bonded to — (CH═CH) _m —Φ ₂ so that the polarization of — (CH═CH) _m —Φ ₂ is promoted.

For example, when n = 0, Φ ₁ is a benzene ring, and the number of R ₁ is 1, that is, when one R ₁ is directly bonded to the benzene ring Φ ₁ , R ₁ is
It is preferable that Φ ₁ is bonded to the diacetylene bond (-C≡C-C≡C-) at the para position, and when there are a plurality of R ₁ , the para position to the diacetylene bond. And is preferably bonded to Φ ₁ at the meta position.

When n = 1, R ₁ is preferably bonded to the vinylene group (—CH═CH—) in the trans position with respect to Φ ₁ . Similarly, when m = 0, Φ ₂ is a benzene ring, and the number of R ₂ is 1, that is, when one R ₂ is directly bonded to the benzene ring Φ ₂ , R is R.
₂ is preferably bonded to Φ ₂ at the para position with respect to the diacetylene bond, and when there are a plurality of R ₂ ,
It is preferable to bond to Φ ₂ at the para position and the meta position with respect to the diacetylene bond.

When m = 1, R ₂ is preferably bonded to the vinylene group (—CH═CH—) in the trans position with respect to Φ ₂ . Both n and m are 0, and Φ
_{When 1} and Φ ₂ are both benzene rings, one of R ₁ and R ₂ is an electron accepting group, the other is an electron donating group, and R ₁ is para to the diacetylene bond. It is preferred that R 2 is bonded to Φ ₁ and R ₂ is bonded to Φ ₂ in a para position with respect to the diacetylene bond because the intramolecular polarization effect is highest.

When both n and m are 1, especially _one of R ₁ and R ₂ is an electron accepting group,
If the other is an electron donating group, R ₁ is bound to the vinylene group in the trans position with respect to Φ ₁ , and R 2 is bound to the vinylene group with the trans position with respect to Φ ₂ , the intramolecular polarization effect is the most. High and preferred.

Φ ₁ and Φ ₂ contained in the compound represented by the above formula (I) may be the same as or different from each other, and each is an aromatic ring or a hetero ring, an aromatic ring or a hetero ring. A 5-membered ring or a 6-membered heterocyclic ring is preferable, and a benzene ring or a 5-membered heterocyclic ring is particularly preferable. Specific examples of these aromatic rings or hetero rings include benzene and
Examples thereof include a 6-membered ring such as pyridine, a 5-membered heterocyclic ring such as thiophene, pyrrole, furan, thiazole and pyrazole, a 10-membered ring such as naphthalene and quinoline, and a heteroaromatic ring such as oxazole and benzothiazole.

In the compound represented by the above formula (I), these aromatic rings or hetero rings provide a field for electron resonance, and the non-linear optical effect is effectively exhibited by these rings. The π-conjugated chain formed by an acetylene bond or the like also provides a field of electron resonance, and the π-conjugated chain allows the nonlinear optical effect to be more effectively exhibited.

R ₃ in the compound represented by the above formula (I)
To R ₄ may be the same or different and each is a hydrogen atom or a group selected from the group consisting of an alkyl group, an aryl group, an aralkyl group and an alkyloxy group. Of these, a hydrogen atom or an alkyl group is preferable, and a methyl group or an ethyl group is particularly preferable when the alkyl group is used.

The above-mentioned alkyl group may be linear or branched and has 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. As such an alkyl group, specifically, a methyl group, an ethyl group, an n-propyl group,
linear alkyl group such as n-butyl group, isopropyl group,
sec-butyl group, sec-amyl group and other secondary alkyl groups, te
Examples thereof include tertiary alkyl groups such as rt-butyl group and tert-amyl group.

The above aryl group may have a substituent. As such an aryl group, specifically,
Examples thereof include a phenyl group, a naphthyl group, a tolyl group and a xylyl group.

Specific examples of the above aralkyl group include:
Examples thereof include a benzyl group, a phenethyl group, an α-methylbenzyl group and a tolylmethyl group. The alkyloxy group may be linear or branched and has 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. As such an alkyloxy group, specifically, a linear alkyloxy group such as methyloxy group, ethyloxy group, n-propyloxy group, n-butyloxy group, isopropyloxy group, sec-butyloxy group, sec -Secondary alkyloxy group such as amyloxy group, tert-butyloxy group,
and tertiary alkyloxy groups such as tert-amyloxy group.

In the compound represented by the above formula (I), it is preferable that R ₃ and / or R ₄ be arranged at a position where the polarization of the whole molecule becomes high. For example, when Φ ₁ and Φ ₂ are benzene rings, R ₃ is bonded to Φ ₁ in the ortho position with respect to the diacetylene bond, and R _{4 is}
Is bonded to Φ ₂ in the meta position with respect to the diacetylene bond, or R ₃ is bonded to Φ ₁ in the meta position with respect to the diacetylene bond and R ₄ is in the ortho position with respect to the diacetylene bond. Is preferably coupled to Φ ₂ . In this case, two R ₃ are each bonded to Φ ₁ in the ortho position to the diacetylene bond, or two R ₄ are each bonded to Φ ₂ in the ortho position to the diacetylene bond. May be. In addition, multiple R in Φ _{1
When 3} is bonded, each R ₃ may be the same or different from each other, and when plural R ₄ are bonded to Φ ₂ , each R ₃ may be the same as each other. May be different.

Further, R ₃ or R ₄ is preferably an optically active group. When R ₃ or R ₄ is an optically active group,
When the symmetry of molecules is broken and a single crystal is produced, it is difficult for adjacent molecules to have central symmetry, and the nonlinear optical property is effectively maintained. Here, the optically active group means a group having an asymmetric carbon atom, one of three different groups at one carbon atom, for example, a methyl group, an ethyl group, or a substituent having a hydrogen atom bonded thereto.

The compound represented by the above formula (I) preferably has at least one deuterium.
Specific examples of the compound represented by the above formula (I) include the following compounds (1) to (5).

[0038]

[Chemical 3]

The diacetylene derivative represented by the above formula (I) has a Φ ₁ skeleton and an ethynyl group and R _1- (CH═CH).
_The compound A having _n − bonded thereto and the compound B having an ethynyl group and R ₂ — (CH═CH) _m — bonded to the Φ ₂ skeleton are reacted in the presence of a catalyst such as divalent copper. Can be obtained by

For example, the compound represented by the above formula (1) is synthesized through the reaction of the following formula.

[0041]

[Chemical 4]

As is clear from the above reaction formula, compound A
The ethynyl groups of B and B are dehydrogenated in the presence of a catalyst to give the desired diacetylene derivative. This reaction is usually performed under an inert atmosphere such as argon or nitrogen.

The organic nonlinear optical material according to the present invention comprises the compound represented by the above formula (I) and is used in a crystallized state. This crystal is preferably a single crystal, but may be a eutectic with another component having a similar crystal structure.

The crystals of the compound represented by the formula (I) as described above may be dispersed in a matrix for use.

[0045]

As described above, the organic nonlinear optical material according to the present invention is made of the organic compound represented by the above formula (I), and is resonated by the Φ ₁ ring, Φ ₂ ring and π-conjugated chain such as diacetylene bond. Is provided, the molecular polarization and the molecular arrangement are balancedly controlled by R ₁ , R ₂ , R ₃ and R ₄ , and an excellent nonlinear optical effect is obtained.

Therefore, the organic non-linear optical material according to the present invention is suitable for application to non-linear optical elements such as optical wavelength conversion elements and electro-optical elements utilizing the second-order or third-order non-linear optical effect.

[0047]

EXAMPLES The present invention will be described below based on more specific examples, but the present invention is not limited to these examples.

[0048]

Example 1 A solution of 2.0 g of o-ethynylphenylaldehyde in 31 ml of pyridine was added to 91 ml of pyridine.
A solution containing 31 g of Cu (II) acetate monohydrate was added dropwise at room temperature over 1.5 hours, and the mixture was further stirred for 2 hours after the addition. The solvent was removed from the obtained reaction solution, and the red solution was developed on an alumina column with hexane / ether (2: 3) to obtain 1.03 g of a product. The product was recrystallized from benzene to give yellow needle crystals.

The melting point (MP), mass spectrum (MS), infrared spectrum (IR) and ^{1 of} this yellow needle crystal were obtained.
The measurement results of the 1 H-NMR spectrum are as follows. MP: 163-164 ° C. MS: m / z 258 (M ⁺ , 100%) IR: 2270, 2200 cm ^-1 (-C≡C-) 1700 cm ^-1 (-CHO) ¹ NMR (90 MHz): 10.60 ppm ( s, 2H, CHO) 7.90-8.10ppm (m, 2H, benzeno
id H) 7.43-7.83 ppm (m, 6H, benzeno
id H) From the above measurement results, the obtained yellow needle crystal was identified as the compound (1).

30 mg of the compound (1) was dissolved in 0.9 ml of dichloroethane, and this solution was placed on a quartz substrate.
It was spin-coated at 000 rpm for 20 seconds and then vacuum dried at 80 ° C. for 1 hour to obtain a thin film having a thickness of 0.092 μm.

The THG intensity was measured by irradiating this thin film with an Nd ⁺ YAG laser. As a result of comparing the THG intensity with that of quartz, it was 0.32 times.

[0052]

Example 2 A solution of 2.0 g of o-ethynylcinnamaldehyde in 25 ml of pyridine was added to 75 ml of pyridine.
A solution containing 24.6 g of Cu (II) acetate monohydrate was added dropwise at a temperature of 52-56 ° C over 1.0 hour,
After the dropping, the mixture was further stirred at the same temperature for 3 hours. After removing the solvent from the obtained reaction solution, the dark brown solution was developed on an alumina column with hexane / ether (1: 4),
1.4 g of product was obtained. The product was recrystallized from hexane / benzene to give yellow needle crystals.

The melting point (MP), mass spectrum (MS), infrared spectrum (IR) and ^{1 of} this yellow needle crystal were obtained.
The measurement results of the 1 H-NMR spectrum are as follows. MP: 203-204 ° C MS: m / z 310 (M ⁺ , 17%), 254.
^{(100) IR: 2200cm -1 (} -C≡C-) 1680cm -1 (-CHO) 980cm -1 (trans-CH = CH-) 1 NMR (90MHz): 10.10ppm (d, J = 8Hz, 2H , CHO) 8.02ppm (d, J = 16Hz, 2H, olefi
nic H) 7.35-7.87 ppm (m, 8H, benzeno
id H) 6.85 ppm (dd, J = 16 Hz, 8 Hz, 2 H,
olefinic H) From the above measurement results, the obtained yellow needle crystal was identified as the compound (2).

0.5 mg of the compound (2) was dissolved in 0.2 ml of dichloroethane, and this solution was spin-coated on a quartz substrate at 2000 rpm for 20 seconds, then 150
It was vacuum dried at 0 ° C. for 1 hour to obtain a thin film having a thickness of 0.3424 μm.

This thin film was irradiated with an Nd ⁺ YAG laser to measure THG intensity. As a result of comparing the THG intensity with that of quartz, it was 0.31 times.

[0056]

EXAMPLE 3 7- (o-Ethynylphenyl) hepta-2,4,6-trienal 3.48 in 33 ml pyridine
The solution containing 3 g of Cu (II) acetate hydrate in 98 ml of pyridine was added dropwise to the solution at a temperature of 52-54 ° C. over 1.5 hours, and the mixture was stirred for 1 hour after addition. did. The red solution after removing the solvent from the obtained reaction solution was developed on an alumina column with benzene / chloroform (7: 3) to obtain 1.97 g of a product. The product was recrystallized from hexane / THF to give red horn crystals.

The melting point (MP), mass spectrum (MS), infrared spectrum (IR) and ^{1 of} this red horn crystal.
The measurement results of the 1 H-NMR spectrum are as follows. MP: 186-188 ° C MS: m / z 414 (M ⁺ , 59%), 396
^{(100) IR: 2200cm -1 (} -C≡C-) 1670cm -1 (-CHO) 1620cm -1 (-CH = CH-) 1600cm -1 (-CH = CH-) 1580cm -1 (-CH = CH −) 1010,980 cm ⁻¹ (trans-CH═CH—) ¹ NMR (90 MHz) 10.41 ppm (d, J = 9 Hz, 2H, CHO) 6.40-7.74 ppm (m, 18H, olefin)
ic and benzenoid H) 6.21 (dd, 17 Hz, J = 9 Hz, 2H, ole)
finic H) From the above measurement results, the obtained red horn crystals were identified as the compound (3).

50 mg of the compound (3) was dissolved in 0.5 ml of dichloroethane, and this solution was placed on a quartz substrate.
Spin coating was performed at 000 rpm for 20 seconds, and then vacuum drying was performed at 80 ° C. for 1 hour to obtain a thin film having a thickness of 0.493 μm.

The thin film was irradiated with an Nd ⁺ YAG laser to measure the THG intensity. As a result of comparing the THG intensity with that of quartz, it was 1.63 times.

Claims (5)

[Claims] 1. A compound represented by the general formula (I): Wherein, [Phi ₁ and [Phi _2, which may be the being the same or different, are each an aromatic ring or heterocycle, n, m is an integer of 0 to 4, R ₁ and R ₂ may be the same or different from each other, each is an electron donating group or an electron accepting group,
The number of R ₁ when R ₁ is attached directly Φ ₁ (n = 0) may be a plurality, in the case R ₂ is attached directly _{Φ 2 (m = 0) R} 2 May be plural and R ₃ and R ₄ may be the same or different from each other and each is a hydrogen atom or a group consisting of an alkyl group, an aryl group, an aralkyl group and an alkyloxy group. It is the group of choice. ] An organic nonlinear optical material comprising an organic compound represented by 2. The organic nonlinear optical material according to claim 1, wherein Φ ₁ and Φ ₂ are benzene rings or 5-membered heterocyclic rings. 3. The organic nonlinear optical material according to claim 1, wherein R ₃ or R ₄ is an optically active group. 4. The organic nonlinear optical material according to claim 1, wherein the organic compound represented by the formula (I) has at least one deuterium. 5. A nonlinear optical element comprising the organic nonlinear optical material according to claim 1.