JPH06130434A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To provide an organic nonlinear optical material which presents a large nonlinear optical effect, does light absorption on the short wavelength side, and ensures good crystallinity, processing easiness, stability, and practical application. CONSTITUTION:An organic nonlinear optical material includes characteristically at least one of the phenylhydrasone as given by Formula (I) or its derivative and phenylhydrazine as given by Formula (I) or its derivative.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonlinear optical material useful for wavelength conversion of laser light, parametric amplification and the like in the fields of optical communication and optical information processing.

[0002]

2. Description of the Related Art In recent years, nonlinear optical materials have attracted attention in the field of optoelectronics. A non-linear optical material is a material in which a substance causes a non-linear response to light due to the interaction between the substance and light. In particular, if the second harmonic generation (SHG), which is a second-order nonlinear optical effect, or the first-order electro-optical (EO) effect (Pockels effect) is used, the wavelength of incident laser light can be converted to ½. It can be applied to electro-optic modulation and optical switching. Therefore, research on nonlinear optical devices having these effects has been actively conducted.

Known non-linear optical materials having the SHG effect are inorganic materials such as lithium niobate (LiNbO ₃ ) and potassium phosphate titanate (KTP).
Research on wavelength conversion devices using SHG has also focused on inorganic nonlinear optical materials. However, recently, from the viewpoint of large optical linearity and high-speed optical response, π
Nonlinear optical materials made of organic materials having an electron conjugated system have been attracting attention, and many studies for material search have been made.

Known organic nonlinear optical materials include urea and 2-methyl-4-nitroaniline (MN).
A), m-nitroaniline, N, N-dimethyl-2-acetylamino-4-nitroaniline (DAN), 3-methyl-4-nitropyridine-N-oxide (POM),
Examples include N- (4-nitrophenyl)-(L) -prolinol (NPP). A detailed description of organic nonlinear optical materials can be found, for example, in the following literatures: (1) "Nonliner Optical Properties of Organic and
Polymeric Materials ", ACS SYMPOSIUM SERIES 233 (198
3), David J. Williams (2) "Nonliner Optical Properties of Organic Mole
cules and Crystals ", vol. 1, 2, Academic Press (198
7), DS Chemla and J. Zyss (3) "Organic nonlinear optical materials", Masao Kato, Hachiro Nakanishi supervision, CMC, Inc. (1985) (4) "New organic nonlinear optical materials I and II", Edited by Takayoshi Kobayashi, Shinsuke Umegaki, Hachiro Nakanishi, and Shino Nakamura, CMC, Inc. (published in 1991).

The optical non-linearity of an organic compound having a π-electron conjugated system is due to the interaction between the laser light, which is a strong electromagnetic wave, and the delocalized π-electron of the organic molecule, that is, the expression of nonlinear polarization. Therefore, in order to increase the non-linear polarization or increase the supramolecular polarizability β of the molecule, an electron-donating substituent (donor) or an electron-withdrawing substituent (acceptor) is introduced into the π-electron conjugated system. The method is a general molecular design method.

Further, a compound in which a large charge transfer occurs between the donor and the acceptor, the absorption maximum wavelength is shifted to the long wavelength side, and as a result, the absorption maximum wavelength is highly likely to be shifted to the visible region. Wavelength 780nm-840nm
When the wavelength conversion element using the semiconductor laser as the light source is used, the second harmonic thereof is 390 nm to 420 nm.
When the compound re-absorbs SHG in the wavelength region of 1, there is a problem that the wavelength conversion element material is deteriorated and the conversion efficiency is lowered. Therefore, the light absorption of the nonlinear optical material is preferably as low as possible in the crystalline state, and particularly, the light absorption short wavelength (λ _{CUT OFF} ) of the nonlinear optical material is 390 n.
It is preferably m or less.

[0007] Inorganic materials such as lithium niobate and KTP, which are currently in practical use, are very expensive and have the disadvantage that their second-order nonlinear performance is not as good as that of organic materials. On the other hand, known organic nonlinear optical materials have the advantage of being inexpensive and relatively easy to synthesize. However, such an organic nonlinear optical material is not suitable for wavelength conversion of a semiconductor laser and easily obtains a large single crystal because the absorption is extended to the visible region and the crystal exhibits yellow or orange color when the SHG efficiency is large. It also has the disadvantage that it is difficult.

The properties required for an organic nonlinear optical material that can withstand practical use include the following: 1) Large optical nonlinearity 2) Wavelength range used, particularly in the range of 390 nm to 420 nm. High optical transparency 3) High crystallinity and easy to form large crystals 4) High mechanical strength and excellent workability 5) Thermally and chemically stable organic nonlinear optical materials known in the past Therefore, a promising material satisfying the above various characteristics has not been found yet.

[0009]

In view of the above problems, the present invention has a large non-linear optical effect, has light absorption on the short wavelength side, has good crystallinity and processability, and is stable and practical. An object is to provide an organic nonlinear optical material.

[0010]

[Means for Solving the Problems] In order to solve the above problems,
According to the present invention, there is provided an organic nonlinear optical material comprising at least one of phenylhydrazone represented by the following chemical formula (I) or its derivative or phenylhydrazine represented by the following chemical formula (II) or its derivative. Provided.

[0011]

[Chemical 7] Y represents O or S, Z is -O-, -S-, -NH.
−, —NR ³ ″ — or a direct bond, n represents an integer of 0 to 20, m represents an integer of 0 to 20,

[Chemical 8]

[Chemical 9] l represents 0, 1, 2, or 3, and M ⁺ represents Li ⁺ , Na
^{Represents +} , K ⁺ , NH ₄ ⁺ , Rb ⁺ or N (R ³ ) ₄ ⁺ ,

[Chemical 10] R ³ ″ has the same definition as R ³ ′, R ³ and R ³ ′ may combine with each other to form a ring,

[Chemical 11] R ¹ 'is independently the same as the definition of R ¹ and l is 2 or 3
In the case of, R ² and R ⁵ may be different or may be independent of each other)

[Chemical 12] In the present invention, phenylhydrazine or its derivative preferably has the following structure (III).

[0012]

[Chemical 13] Here, R ¹ , R ² , R ³ 'and l are as defined above. In formula (III), Z is preferably a direct bond or -NH-. Further, preferably R ³ 'is represented by R ⁶ below.

[0013]

[Chemical 14] Here, R ⁸ is a linear or branched alkyl group having 1 to 20 carbon atoms.

The following points are taken into consideration when designing the molecule of the organic compound for the organic nonlinear optical material represented by the above general formula of the present invention.

1) The optical nonlinearity of the organic material is caused by the distortion of the π-electron system due to the interaction with light. Therefore, the distortion is increased, that is, the supramolecular polarizability β of the molecule is increased. Thus, the donor-acceptor is introduced into the π-electron conjugated system.

2) When the charge transfer interaction between the donor and the acceptor and the resonance effect are too large, the β of the molecule increases dramatically. However, along with this, the maximum absorption wavelength shifts to the long wavelength side, so select the optimal donor-acceptor combination so that the light absorption is on the short wavelength side as much as possible and β does not become too small. To do.

The compounds that are particularly preferably used as the organic optical nonlinear material of the present invention are shown below, but the scope of the present invention is not limited to these compounds.

[0018]

[Chemical 15]

[Chemical 16]

[Chemical 17]

[Chemical 18]

[Chemical 19]

[Chemical 20]

[Chemical 21]

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24]

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

[Chemical 28]

[Chemical 29]

[Chemical 30]

[Chemical 31] The nonlinear optical material of the present invention may use the compound represented by the above chemical formula (I) or (II) as a single crystal.
Further, the compound represented by the above chemical formula (I) or (II) may be used alone or as a mixture of two or more kinds, or a composition in which the compound or a mixture thereof is dispersed or solid-dissolved in a polymer. You may use it as a thing. Examples of such a polymer useful in the present invention include, for example,
Polyester, polyamide, polyacrylate, polymethacrylate, polycarbonate, polyvinyl chloride, polyether, polystyrene, polyolefin, polyacrylonitrile, polyvinyl pyridine, polyvinyl pyrrolidone, polyvinyl carbazole and polysulfone, etc.
There are also copolymers of these. A film-shaped organic nonlinear optical material can be formed by dispersing or solid-dissolving in a polymer. When the above compound is used as a second-order organic nonlinear optical material, it is preferable that the compounds are non-centrosymmetrically oriented in the same direction. The orientation means is, for example,
Polymer Communications Magazine (Volume 30, 40)
Pp. 43, 1989). This document is incorporated herein as a reference to the present invention.

Further, when hydrogen in the compound used in the present invention is deuterated, a shift effect of near-infrared absorption is exhibited, but with respect to a nonlinear effect, a deuterated compound and a compound not deuterated. There is no difference. Therefore, in the compound represented by the above structural formula, part or all of hydrogen may be replaced with deuterium.

Some of the compounds used in the present invention have an asymmetric carbon in the molecule. In such a case, the R-form and S-form compounds are present from the viewpoint of stereochemistry. In the present invention, the compound having an asymmetric carbon atom in the molecule can be used in either the R form or the S form,
Further, a mixture of R-form and S-form can be used as well.

The organic nonlinear optical material of the present invention is a secondary nonlinear optical process element such as a bulk type wavelength conversion element, a plane waveguide type wavelength conversion element and a fiber type tooth conversion element.
It is extremely useful as an optical waveguide element and an optical frequency doubler conversion element.

Examples of the compounds used in the present invention are shown below, but the scope of the present invention is not limited to these examples.

[0023]

Example 1 Preparation of 4-cyanophenylhydrazine

[Chemical 32] 23.62 grams (0.2 mol) of 4-aminobenzonitrile was suspended in a mixture of 50 milliliters of concentrated hydrochloric acid and 50 milliliters of water. The suspension was then cooled to 2 ° C with vigorous stirring. With continued vigorous stirring of the suspension, 17.25 grams (0.25 mole) of sodium nitrite solution in 100 ml of water was slowly added dropwise. During the dropping, the temperature of the suspension was controlled not to exceed 5 ° C. The sodium nitrite solution was added dropwise until the nitrite test (iodine starch paper) became positive even after 20 minutes. The resulting suspension of the thermally labile diazonium chloride salt was used directly in the next preparative step. Note that this suspension should not be left for a long time.

Sulfur dioxide gas was added to a 1 mol sodium hydroxide solution dissolved in 300 ml of water while cooling and stirring. Sulfur dioxide gas was added until the pH of the solution was 7. The solution was then cooled to 3 ° C and 30 grams of ice was added. The above diazonium salt suspension was added rapidly with vigorous stirring of the solution. After heating to 20 ° C. and stirring for 10 minutes, the slightly acidic reaction mixture was heated to 70 ° C. and stirred for 8 hours. Then 150 ml of concentrated hydrochloric acid was added to this suspension and cooled to -5 ° C. At this temperature, the hydrazine hydrogen chloride adduct was collected by filtration.

To the hydrogen chloride adduct, 100 ml of 25% sodium hydroxide was added and stirred, and hydrazine was extracted with methylene chloride to form the hydrogen chloride adduct in a free base form. After removing the methylene chloride in vacuo, the crude product was washed with a little toluene (50-100).
(Ml). As a result, 15.4 g of yellow-orange crystals were obtained. The melting point of this crystal is 85
It was ℃. The physical properties of this crystal were as follows (calculated as C ₇ H ₇ N _{3 with a} molecular weight of 133.15).

IR (KBr pellet) ν: 3401,
3327.7, 2210.8, 1603.1, 151
4.4, 1470.0, 1338.8, 1286.7,
1180.6, 1155.5, 1007.0, 943.
3,839.2,825.7,551.7,528.
6,476.5 [cm ⁻¹ ] · ¹ H-NMR (DMSO, 90 MHz) δ: 7.72
(1H, NH-ar), 7.42 (2H, d, ar-
H), 6.81 (2H, d, ar-H), 4.24 (2
_{H, -NH 2) [ppm]} · Calcd C: 63.14%, H: 5.30
%, N: 31.56% Analytical value C: 63.5%, H: 5.3%, N: 31.3
%

[0027]

Example 2 4-Methylthiobenzaldehyde- [4′-cyanophe
Nilhydrazone]

[Chemical 33] 5.0 grams (37.6 mmol) of 4-cyanophenylhydrazine was dissolved in a mixture of 100 milliliters of ethanol and 10 milliliters of acetic acid at 25 ° C. 5.72 dissolved in 50 ml ethanol
A solution of 3 grams (37.6 mmol) 4-methylthiobenzaldehyde was added to the above solution. After the addition of the solution was complete, the resulting suspension was heated to reflux for 2 hours.
After cooling, the precipitate was collected and recrystallized from 600 ml of toluene. As a result, 8.79 g (32.9 mmol, 87%) of a pale yellow powder was obtained. The melting point of this powder was 194 ° C. The physical properties of this crystal were as follows (C ₁₅ H ₁₃ N ₃ S having a molecular weight of 267.35).
Calculated as).

IR (KBr pellet) ν: 3262.
1, 2220.4, 1607.0, 1597.3, 15
25.9, 1493.1, 1421.8, 1315.
7,1298.3,1279.0,1263.6,11
71.0, 1130.5, 1099.6, 949.1,
920.2, 835.3, 817.9, 549.8, 5
18.9 [cm ⁻¹ ] · ¹ H-NMR (DMSO, 90 MHz) δ: 10.9
2 (1H, s, CH = N), 7.94 (1H, s, N-)
NH), 7.7-7.5 (4H, m, ar-H), 7.
3-7.1 (4H, m, ar-H), 2.51 (3H,
_{s, S-CH 3) [} ppm] · Calcd C: 67.39%, H: 4.90
%, N: 15.72% Analytical value C: 67.44%, H: 4.88%, N: 1
5.47%

[0029]

Example 3 3-Methoxy-4-hydroxybenzaldehyde-fe
Preparation of nilhydrazone

[Chemical 34] 10.814 grams (0.1 mole) of phenylhydrazine was dissolved at 25 ° C. in a mixture of 100 ml of ethanol and 10 ml of acetic acid. 15.
A solution of 215 grams (0.1 mole) of 3-methoxy-4-hydroxybenzaldehyde in 50 milliliters of ethanol was added to the above mixture. After the addition of the solution was complete, the resulting clear suspension was heated to reflux for 2 hours. After cooling, the ethanol was removed in vacuo to give a brown solid. The solid was recrystallized from 2.5 liter cyclohexane. As a result, 18.2 g (75 mmol, 75%) of pale yellow pasty crystals were obtained. The melting point of this crystal was 252 ° C. The physical properties of this crystal were as follows (molecular weight: 242.28).
Calculated as C ₁₄ H ₁₄ N ₂ O ₂ ).

IR (KBr pellet) ν: 1602.
1,1507.6,1443.9,1427.5,12
65.5, 1240.4, 1116.0, 1069.
7, 1031.1, 915.4, 750.4, 693.
5,507.4,449.5,418.6 [cm ^-1 ]

[0031]

Examples 4-11 The compounds listed in Table 1 were prepared.

[0032]

[Table 1] In Table 1, the compounds according to Examples 4 to 9 were prepared by the same method as in Examples 2 and 3 above. Further, the compounds according to Examples 10 and 11 were recrystallized from a commercial product (manufactured by Lancaster) from a solvent.

[0033]

Example 12 Measurement of NLO characteristics SHG powder measurement was performed on the compound prepared as described above. The fundamental frequency was 830 nm. This measuring method is described in S. K. Kurtz, T .; T. Per
ry's "A powder technique fo
r the evaluation of nonli
J. Near optical materials ". Appl. Phys. Magazine (Vol. 39, 379)
8-1381, 1968). This document is incorporated herein as a reference for the present invention. For some compounds, the chromophore μβ values were determined by the solvatochromic method. Unless otherwise stated, the long-wavelength absorption maximum was determined by UV spectroscopy in chloroform solution. For the solvatochromic method, see M.K. S. Paley, J .; M. Harris
S.H. Louser, J .; C. Baumert, G .;
C. Björklund, D.M. Jundt, R.M. J. T
Wieg's "A solvatochromic me
how for determining seco
nd-order Polarizabilities
of organic molecules ". Org. Chem. Magazine (Volume 54, 3774-
Pp. 3778, 1989). This document is incorporated herein as a reference for the present invention.

The measurement results are shown in Table 2 together with the melting points and the maximum absorption wavelengths of the crystals of the compounds of each example.

[0035]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication location C07C 309/46 7419-4H 323/48 7419-4H C09K 9/02 Z 7188-4H (72) Invention Satoshi Funato 2419-4 Matoba, Kawagoe-shi, Saitama Prefecture 201 (72) Inventor Yuto Tsutomu Room 29-1 303 Wakita Honcho, Kawagoe City, Saitama Prefecture (72) Inventor Donald Lupo 6238 Epstein, Germany 2, Am-Holder Bush 28 (72) Inventor Robert A. Norwood 3-23-15 Toyodaminami, Nerima-ku, Tokyo Toyomas Homes 102

Claims (7)

[Claims] 1. An organic nonlinear optical material containing at least one of phenylhydrazone represented by the following chemical formula (I) or a derivative thereof or phenylhydrazine represented by a chemical formula (II) or a derivative thereof. [Chemical 1] Y represents O or S, Z is -O-, -S-, -NH.
-, -NR ³ ″-or a direct bond, n represents an integer of 0 to 20, m represents an integer of 0 to 20, and [Chemical 3] l represents 0, 1, 2, or 3, and M ⁺ represents Li ⁺ , Na
^{Represents +} , K ⁺ , NH ₄ ⁺ , Rb ⁺ or N (R ³ ) ₄ ^+, and R 3 ^'' is, R ³ 'are as defined for, are linked to each other R ³ and R ^3' may form a ring, embedded image R ¹ 'is independently the same as the definition of R ¹ and l is 2 or 3
In the case of, R ² and R ⁵ may be different from each other or may be independent of each other. 2. The organic nonlinear optical material according to claim 1, which is dispersed or solid-dissolved in a polymer substance and has a non-centrosymmetric orientation. 3. The organic nonlinear optical material according to claim 1, which is crystallized and has a non-centrosymmetric orientation. 4. The organic nonlinear optical material according to claim 1, which is in the form of a film. 5. The organic nonlinear optical material according to claim 1, which is for an optical waveguide. 6. The organic nonlinear optical material according to claim 1, which is for a second-order nonlinear optical process. 7. The organic nonlinear optical material according to claim 1, which is for optical frequency doubler conversion.