JPH07117671B2 - Organic nonlinear optical material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic nonlinear optical material applicable to various optical elements.

[Conventional technology]

Non-linear optical materials have the function of converting the frequency of light, such as second harmonic generation (hereinafter abbreviated as SHG) and third harmonic generation (hereinafter abbreviated as THG), as well as these characteristics. Since it can be applied to optical switches and optical memories that make full use of it, active research and development is being promoted as a central material for future optical devices. Among them, organic nonlinear optical materials have characteristics such as larger nonlinear optical constants and faster response than conventional inorganic ferroelectric crystals, so a wide range of materials can be searched for for practical application of future optical devices. Has been done.
However, in making various elements using these organic materials into elements, it is necessary to grow large crystals or to crystallize thin films, and even when these crystals are obtained, the mechanical strength of the crystals is It has disadvantages such as inferiority or poor workability.

[Problems to be solved by the invention]

In order to overcome these drawbacks, there are methods such as dispersion of a nonlinear optical material in a polymer, but there is a problem of compatibility with the polymer, and it is not possible to disperse and blend an efficient nonlinear optical material in a high concentration. difficult. Moreover, the polymer-based material thus obtained is not a highly efficient material as a non-linear optical material, and does not have stable characteristics over time.

An object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide a highly efficient nonlinear optical material having excellent moldability and mechanical strength.

[Means for solving problems]

When the present invention is outlined, all the present invention relates to organic nonlinear optical materials, and the first invention is that the ester moiety of an unsaturated carboxylic acid ester has the following general formula I: O ₂ N-Z. _{1 -X = Y-Z 2 -NR} 1 R 2 ...... (I) (wherein Z ₁ and Z ₂ are the same or different, [pi 2 divalent cyclic group-conjugated, X and Y are identical, CH Or N, R ₁ and R ₂ are the same or different and represent hydrogen or an organic group, but at least one of R ₁ and R ₂ is an organic group having a reactive functional group)
It is characterized in that it is a monomer to which the compound represented by

A second invention is a homopolymer of the organic nonlinear optical material of the first invention, or at least one monomer selected from the group consisting of the organic nonlinear optical material and acrylic acid ester, methacrylic acid ester and styrene. It is a copolymer with.

The third invention is a graft polymer of the organic nonlinear optical material of the first invention and a polyacrylic acid ester, a polymethacrylic acid ester, polystyrene or a copolymer thereof.

The main feature of the nonlinear optical material according to the present invention is that the nonlinear optical material itself has a polymerization ability, and the polymer of the polymerizable nonlinear optical material has a high nonlinear optical effect and moldability,
It is excellent in mechanical strength. This is a solution to the drawback of the prior art that it is difficult to disperse and blend an efficient nonlinear optical material in a high concentration by designing and synthesizing a polymerizable nonlinear optical material having a high nonlinear optical effect and polymerizing the same. .

The non-linear optical material having polymerization ability in the present invention refers to a compound group in which a compound represented by the following formula II or III is bonded to the ester moiety of an unsaturated carboxylic acid ester such as acrylic acid ester or methacrylic acid ester. . In each formula, the symbols Z ₁ , Z ₂ , R ₁ and R ₂ have the same meanings as in formula I above.

_{O 2 N-Z 1 -CH =} CH-Z 2 -NR 1 R 2 ...... (II) _{O 2 N-Z 1 -N =} N-Z 2 -NR 1 R 2 ...... (III) Z ₁ and Z ₂ is a π-electron conjugated divalent cyclic group such as a benzene ring, a pyridine ring, a pyrimidine ring, a furan ring, a thiazole ring, an oxazole ring, an oxadiazole ring, and a naphthalene ring. It may have a different structure. These compounds are compounds represented by formula II or III with unsaturated carboxylic acid chlorides such as acrylic acid chloride or methacrylic acid chloride, wherein at least one of R ₁ and R ₂ has a hydroxyl group, an amino group, a mercaptyl group, etc. It is generally synthesized by the addition reaction of ## STR1 ## but, since this reaction affects the central C = C, N = N bond of the compound represented by the formula II or III, There are some that are not synthesized. In this case, after reaction with acrylic acid chloride or methacrylic acid chloride, C = C, N =
It is necessary to take a synthetic route connecting the left and right by N-bonding. Also,
The compound represented by the formula II or III, which is a part of the molecule having a non-linear optical effect having a polymerization ability in the present invention, has heretofore been partially studied as a second-order non-linear optical material. As a third-order nonlinear optical material that places emphasis on, there has been no study so far.

The present polymerizable compound can be polymerized alone, copolymerized with another monomer, or graft-polymerized to various polymers. In either case, polymerization is easily carried out by a radical initiator such as azobisisoptyronitrile (hereinafter abbreviated as AIBN). A polymer obtained by any method of homopolymerization, copolymerization or graft polymerization can be easily molded into a film by cast or hot press. The mechanical properties depend on the molecular weight of the obtained polymer and the polymerization fraction of the compound represented by the formula II or III in the polymer. Further, the larger the weight fraction, the greater the non-linear optical effect. As a polymerization method, a solution polymerization by a radical reaction using AIBN as an initiator can be generally used, but the present invention is not limited to the polymerization method.

In the present invention, regardless of the polymerization reaction of the nonlinear optical material having the above-mentioned polymerization ability, the compound represented by the formula II or III reacts with the polymer represented by the formula II or III to react with the compound represented by the formula II or III. The polymer obtained by introducing into the side chain is also included in the present invention. For example R ₁ , R in formula II or III
_{When 2} has a hydroxyl group, it reacts with a polymer having reactivity with a hydroxyl group in these compounds, for example, polyacrylic acid chloride or polymethacrylic acid chloride or chloromethylated polystyrene or a copolymer thereof to give a compound represented by the formula II or III. The compound represented is introduced into the side chain of the polymer. As described above, the polymer obtained by the high molecular reaction is also a non-linear optical material which is easy to mold and has excellent mechanical properties, like the polymer obtained by the above polymerization. However, since the weight fraction of the compound represented by the formula II or III introduced by this method is considerably limited, the nonlinear optical characteristics are limited accordingly. That is, in terms of nonlinear optical characteristics, a polymer obtained by polymerization of a nonlinear optical material having the above-mentioned polymerization ability is superior to a polymer obtained by a polymer reaction.

The structural examples of the monomer or polymer used in the material of the present invention are shown below, but the present invention is not limited thereto.

Production example 1 4-Nitro-4 '-[N-ethyl-N- (2-hydroxyethyl) amino] azobenzene (5 g) in dioxane (150 ml)
And 0.4 ml of quinoline as a catalyst was added thereto. 0.4 ml of acrylic acid chloride was added dropwise to this solution under ice cooling, and the mixture was reacted at room temperature for 18 hours. After the reaction was completed, the insoluble matter was removed and water was added to the residue to cause precipitation. The impurities were recrystallized from cyclohexane to obtain the monomer of the above formula VI.

Production example 2 In Preparation Example 1, as the compound corresponding to the formula I, 4-
Nitro-4 ′-[N-methyl-N- (2-hydroxyethyl) amino] stilbene was used, and the same reaction procedure was carried out using methacrylic acid chloride instead of acrylic acid chloride to obtain a monomer of the above formula VII. Got the body

Production Example 3 70 ml of dehydrated and dried dioxane and methyl methacrylate 4.
5 g, 4-nitro-4 '-[N-ethyl-N- (2-acryloyloxyethyl) amino] azobenzene (VI) 1.
After dissolving 5 g and 0.14 g of AIBN and completely degassing, the container was sealed. After reacting this at 60 ° C. for 24 hours, the reaction product was poured into petroleum ether to cause precipitation. After washing with methanol and drying, a polymer of the above formula VII was obtained. Its production was confirmed by IR and NMR spectra.

Production Example 4 5 g of a 1: 1 copolymer of methyl methacrylate and methacrylic acid chloride was dissolved in 100 ml of dioxane, to which 1 ml of quinoline and 4-nitro-4 '-[N-methyl-N-
(2-Hydroxyethyl) amido] stilbene (1.5 g) was added, and the mixture was reacted at 60 ° C. for 10 hours. The product was poured into petroleum ether and the precipitate formed was washed thoroughly with methanol to obtain the above formula.
A polymer of XI was obtained. Its production was confirmed by IR and NMR spectra.

Production Example 5 The same reaction procedure was carried out by using styrene instead of methyl methacrylate in Production Example 3 to obtain a polymer of the above formula X.

Production Example 6 Polystyrene having a methacrylate group at the terminal [Chemlink (trade name) 450 manufactured by Sartomer Co., Ltd.]
0] 5 g and 4-nitro-4 ′-[N-methyl-N- (2
-Methacryloyloxyethyl) amino] stilbene (VII) (1.5 g) was dissolved in benzene (60 ml), and AIBN 0.1
After adding 1 g and completely degassing, the container was sealed. this
The reaction was carried out at 70 ° C for 8 hours, and the reaction product was poured into petroleum ether to cause precipitation. Then, the unreacted monomer was dissolved in hot ethanol and removed to obtain a polymer of the above formula XI.

〔Example〕

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Examples 1 and 2 Non-linear optical characteristics (THG and SBG intensities) of the materials represented by Structural Formulas VI and VII obtained in Production Examples 1 and 2 were measured as organic nonlinear optical materials having polymerization ability.

The THG intensity is 1.9 μm and the SHG intensity is 1.06 μm with the fundamental wave as the powder method [SK Kurz et al., Journal of Applied Physics (J.Appl.Phys.)
39, p. 3798 (1968)]. The results are shown in Table 1 below.

As is clear from Table 1, all the materials of the present invention showed high THG strength. On the other hand, the SHG strength is extremely low, which is below urea. That is, this material is characterized by having a small second-order nonlinear optical effect and a large third-order nonlinear optical effect.

Examples 3 to 6 As the polymer-based organic nonlinear optical material, the above-mentioned Production Example 3 was used.
The non-linear optical constants χ ⁽³⁾ of the materials represented by Structural Formulas VIII to XI obtained in ~ 6 were measured.

This value was determined by the THG maker fringe method using a film-like sample with a fundamental wave of 1.9 μm [F. Kaijar et al., Physical Review A (Phys. Rev.
A) Vol. 32, p. 2352 (1985)]. Standard substance is CS
₂ [χ ⁽³⁾ = 1.78 × 10 ^-13 esu] [see BF Levine et al., Journal of Chemical Physics (J. Chem. Phys.) Vol. 63, page 2666 (1975)]. The respective results are shown in Table 2 below together with Comparative Examples.

As is clear from Table 2, the material of the present invention is an order of magnitude larger than LiNbO ₃ which is a typical inorganic nonlinear optical material.

〔The invention's effect〕

As described above, the organic nonlinear optical material of the present invention,
Both have the advantage that the third-order nonlinear optical effect is large. Further, the organic non-linear optical material having a polymerization ability according to the present invention can be used as a raw material when synthesizing an organic non-linear optical material excellent in moldability and mechanical strength. A polymer-based material using this as a raw material has advantages such as a large third-order nonlinear optical effect and the fact that it can be easily formed into a film shape. Therefore, an optical element using the third-order nonlinear optical effect, for example, an optical bistable element is used. It can be widely used as a central material for future optical integrated devices for optical communication such as optical switches and optical memories.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshikuni Kaino, Tokai-mura, Ibaraki Prefecture Tokai-mura, Shirahoji 162 Shirane, Nippon Telegraph and Telephone Corporation, Ibaraki Telecommunications Research Institute (72) Inventor Taka Kurihara Naka-gun, Ibaraki Prefecture Tokai-mura, Shirahata, Shirahone 162, Nippon Telegraph and Telephone Corporation, Ibaraki Electro-Communications Research Laboratory (72) Inventor, Keiichi Egawa 1-1-1, Sonoyama, Otsu, Shiga Toray Co., Ltd. Shiga Business Office (56) Reference Reference JP-A-62-235934 (JP, A)

Claims (3)

[Claims] 1. At the ester moiety of an unsaturated carboxylic acid ester, the following general formula I: O ₂ N-Z ₁ -X = Y-Z ₂ -NR ₁ R ₂ ... [I] (wherein Z ₁ and Z ₂ is the same or different, a π-electron conjugated divalent cyclic group, X and Y are the same, CH or N, R ₁ and R ₂ are the same or different, and represent hydrogen or an organic group, but R ₁ and At least one of R ₂ is an organic group having a reactive functional group)
An organic nonlinear optical material, which is a monomer to which a compound represented by 2. An ester moiety of an unsaturated carboxylic acid ester having the following general formula I: O ₂ N-Z ₁ -X = Y-Z ₂ -NR ₁ R ₂ ... [I] (wherein Z ₁ and Z ₂ is the same or different, a π-electron conjugated divalent cyclic group, X and Y are the same, CH or N, R ₁ and R ₂ are the same or different, and represent hydrogen or an organic group, but R ₁ and At least one of R ₂ is an organic group having a reactive functional group)
A homopolymer of an organic non-linear optical material which is a monomer to which a compound represented by the formula (1) is combined, or at least one kind of monomer selected from the group consisting of the organic non-linear optical material, acrylic acid ester, methacrylic acid ester and styrene An organic nonlinear optical material characterized by being a copolymer with the body. 3. An ester moiety of an unsaturated carboxylic acid ester having the following general formula I: O ₂ N-Z ₁ -X = Y-Z ₂ -NR ₁ R ₂ ...... [I] (wherein Z ₁ and Z ₂ is the same or different, a π-electron conjugated divalent cyclic group, X and Y are the same, CH or N, R ₁ and R ₂ are the same or different, and represent hydrogen or an organic group, but R ₁ and At least one of R ₂ is an organic group having a reactive functional group)
An organic non-linear optical material which is a monomer to which a compound represented by is bound and a graft polymer of polyacrylic acid ester, polymethacrylic acid ester, polystyrene or a copolymer thereof. Optical material.