JPH0451223A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain a specified compd. liable to form a structure having no reversal symmetry and exhibiting high nonlinear optical characteristics by introducing a cyano substd. alkyl group independently of a conjugated system. CONSTITUTION:This optical material contains a compd. represented by the formula (where A is aryl which may have a substituent or a residue of a hetero ring which may have a substituent, each of R<1> and R<2> is H or alkyl which may have a substituent and at least one of R<1> and R<2> is cyano substd. alkyl). The compd. is easily obtd. by bringing a benzaldehyde derive. and ketones such as an acetophenone deriv. into a reaction in alcohol in the presence of a basic or acidic catalyst.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an organic nonlinear optical material used in fields such as optical recording, optical communication, and optical information processing.

A nonlinear optical effect is one in which the polarization of a substance induced by the electric field of light exhibits a nonlinear response to the electric field strength. Among them, the effect proportional to the square of the electric field of light is:
They include second harmonic generation (SHG), optical balata), IJ-tsuk oscillation, and electro-optic effects, and can be applied to laser light wavelength conversion elements, optical signal modulation elements, etc.

[Conventional technology]

Conventionally, inorganic crystalline materials (such as KH2PO4) have been put into practical use as materials exhibiting the above-mentioned nonlinear optical effect, but the nonlinear optical constants of these materials are small, making it difficult to operate devices using them. High voltage or extremely high light intensity was required. However, in recent years, organic materials having a π-electron conjugated system that exceeds these inorganic materials in terms of nonlinear optical constants have been discovered and are attracting attention. Regarding such materials, there are, for example, the following reports, but only benzene derivatives such as 2-methyl-4-nitroaniline (abbreviated as MNA) are mentioned as a representative example.

Non1inear 0ptical Property
ies of Organic and Polymer
ic Materials AC8SThiPO8I
UMSERIES 233 (D, J, Wi111!
ams (ed. 1983)) In addition, conventionally known organic materials such as those mentioned above do not have sufficient nonlinear optical effects, have considerably long absorption wavelengths that limit the usable wavelength range, or have problems with phase matching conditions. There are various problems such as unsatisfactoriness, and the reality is that it has not yet been put into practical use.

On the other hand, such organic materials not only have a large hyperpolarizability β, which represents the nonlinear optical properties of molecules, but also
In the crystal, it is required to have an arrangement that does not have inversion symmetry and is moreover effectively reflected in the hyperpolarizability β of the molecule. On the other hand, a method for increasing the hyperpolarizability β of a molecule is to introduce a strong electron-donating group such as an amine group or a strong electron-accepting group such as a nitro group or cyan group into the conjugated system of the molecule. It is known that the hyperpolarizability of molecules can be easily increased.

[Problem to be solved by the invention]

However, when using the conventionally known method as described above, the dipole moment of the molecule increases at the same time, and as a result, there is a strong tendency for the crystal to adopt an arrangement with inversion symmetry, and the expected effect may not be obtained. The problem was that there were a lot of

An object of the present invention is to provide an organic nonlinear optical material that can solve the conventional problems as described above and exhibits a novel high nonlinear optical effect.

[Failure to solve the problem]

In order to achieve such an objective, the present inventors introduced a substituent with a large dipole moment in a form independent of the conjugated system of the molecule, thereby changing the direction and size of the dipole moment of the entire molecule. Based on the technical concept that is considered to be effective, as a result of intensive research, we found that a specific compound in which a cyanogen-substituted alkyl group was introduced in a form independent of the conjugated system of the molecule exhibits inversion symmetry. It was discovered for the first time that it is easy to form a structure with no fibers and exhibits high nonlinear optical properties, and the present invention was achieved based on this discovery. That is, the present invention is based on the following general formula CI)R& (wherein A represents an optionally substituted aryl group or an optionally substituted heterocyclic residue, R1,
R2 represents a hydrogen atom or an alkyl group which may have a substituent, and at least one of them represents an alkyl group substituted with a cyan group. ) The gist of this invention is an organic nonlinear optical material characterized by containing a compound represented by the following.

The present invention will be explained in detail below.

In the compound represented by the general formula (1) used in the present invention, examples of the aryl group represented by A include phenyl group, naphthyl group, anthryl group, etc., and examples of the heterocyclic residue represented by A include: Examples include a pyridine ring, a furan ring, a thiophene ring, and a carbazole ring.

In addition, the substituents that each of the above aryl group or heterocyclic residue represented by A may have include fluorine atom, chlorine atom, bromine atom, iodine atom, etc.; rogen atom; methyl group, ethyl alkyl groups, such as a propyl group; a substituted or unsubstituted amino group, such as an alkylamino group, a dialkylamino group, a diphenylamino group, or an amine group;
Examples include alkoxy groups such as methoxy group and ethoxy group; alkylthio groups such as thiomethyl group; tonoalkoxycarbonyl group such as methoxycarbonyl group and ethoxycarbonyl group; nitro group;

R' and R2 each represent a hydrogen atom or an alkyl group which may have a substituent, and at least one of them represents an alkyl group substituted with a cyan group. As this cyan group-substituted alkyl group, 14, -cH2CN
, -CH2CH2CN.

-CH2CH2CH2CN, -CH2CH(CN)
Examples include CH3°-CM(CN)CM2CH2CN. Further, examples of the alkyl group which may have a substituent represented by either R' or R2 include lower alkyl groups such as a methyl group, an ethyl group, and a propyl group; In addition to the cyan group that is essential in the present invention, examples of substituents that may be included include halogen atoms such as chlorine atoms; alkoxy groups such as methquine and ethoxy groups; alkylthio groups such as thiomethyl group, etc. Groups include alkoxycarbonyl groups such as methoxycarbonyl and ethoxycarbonyl groups; amino groups; and hydroquine groups.

Next, preferred compounds represented by the forepaw general formula (I) in the present invention are specifically illustrated in Table 1 below, but the present invention is not limited to these examples.

The compound of the forepaw general formula (1) used in the present invention is a benzaldehyde derivative represented by the following general formula (1) (wherein R1 and R2 have the same meanings as in the forepaw general formula (I)). Aldehyde and the following general formula (1) % formula % () (wherein A has the same meaning as in the forepaw general formula (1)).

) can be easily obtained by reacting ketones such as acetophenone derivatives or acetylated heterocyclic derivatives represented by the following in alcohol in the presence of a basic or acidic catalyst. Note that during the reaction, a solvent other than alcohol, such as tetrahydrofuran, may be added as necessary.

The compound of the present invention obtained in this way has a single crystal form as well as
For example, powder form, mixture form with polymer/liquid crystal, etc.
It can be used as a nonlinear optical material in various forms, such as in the form of a thin film deposited on a substrate. The compound of the present invention can also be used in the form of a pendant, bonded to various polymer skeletons such as acrylic resins.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 (1) Synthesis of compound (1) exemplified in Table 1 above p-Zineanoethylaminobenzaldehydonone 18F was dissolved in sooml of a mixed solvent of methanol:tetrahydrofuran = 5:1 (volume ratio), and 10% NaOH Aqueous solution 20ml
was added dropwise, stirred at room temperature, allowed to react for over 10 hours, and the precipitated crystals were collected from door to door. This was purified by silica gel column chromatography and recrystallized to obtain the title compound 8.
．． I got 1 F.

CHN Theoretical value (%) 76.57 5.81 1176 Measured value (CH) 76.82 5.87 1450
The infrared absorption spectrum of this compound was as shown in FIG. 1 of the attached drawings.

(2) Measurement of second-order nonlinear optical effect The compound (1) of Table 1 of the present invention obtained in (1) above was crushed in a mortar, and the method of Kurtz et al. (J, AppJ, P
hys, 39 (1968) 3798), second harmonic generation (SHG) in the powder state was measured.

For measurement, Nd:YAG sensor (pulse width 6 n5ec
, output 50 mJ/pulse, wavelength z, 064 μm) was used as a light source to detect light of s32 nm among the scattered light from the sample.

The SHG strength of example compound (■) measured in this way is:
The relative value with respect to urea was approximately 60, indicating that this compound has high nonlinear optical properties.

Comparative Example 1 A similar compound represented by the following structural formula in which two methyl groups were substituted for the two methyl groups in the exemplified compound (■) clarified in Example 1 was subjected to the method of Example 1 (1). When the second-order nonlinear optical effect of the compound was measured in the same manner as in Example 1 (2), SH
It showed no G activity.

〔Effect of the invention〕

4゜The compound represented by the forefoot general formula (1) used in the present invention is a novel compound that has an extremely high SHG intensity of approximately 60 relative to urea, and exhibits a high nonlinear optical effect. The organic nonlinear optical material of the present invention is extremely useful as a nonlinear optical material used, for example, in wavelength conversion elements, light modulation elements, and the like.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the infrared absorption spectrum of Exemplified Compound (1) in Table 1 obtained in Example 1.

Claims (1)

[Claims] (1) The following general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼……(I) (In the formula, A is an aryl group that may have a substituent or an aryl group that may have a substituent. Represents a good heterocyclic residue, R^1
, R^2 represents a hydrogen atom or an alkyl group which may have a substituent, and at least one of them represents an alkyl group substituted with a cyano group. ) An organic nonlinear optical material characterized by containing a compound represented by: