JPH01281438A - Nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain an novel org. nonlinear optical material which hardly forms an inverted symmetrical form in the bulk state such as crystal state or thin film state, etc., having substantially no absorption in visible region, and exhibiting high nonlinear optical effect by constituting the material of a specified compd. CONSTITUTION:A compd. expressed by the formula I is used for constituting the title nonlinear optical material. In the formula I, D is an electron donative group; C is a univalent org. group; m is an integer 1-3; n is zero or an integer 1-3; when n is >=2, C contained in plural numbers may be same or different to each other, or may form a condensed ring by connecting with each other. The compd. can be used as a nonlinear optical material in several forms such as single crystal, powder, soln., thin film(Langmuir-Blodgett's film, vapor- deposited film, etc.) deposited on a base body, or in the form blended in a polymer or a liquid crystal molecules, etc. Thus, an org. nonlinear optical material having substantially no absorption in visible region, becoming hardly inverted symmetrical in the form when it is used, and generating high secondary high harmonics, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is suitable for use in nonlinear optical elements and optical devices including the elements. This paper relates to nonlinear optical materials.

[Background of the invention]

The nonlinear optical effect that appears prominently when a material is irradiated with intense light such as a laser beam can be applied to wavelength conversion, intensity modulation, switching, etc., and in recent years, there has been a lot of exploration research into materials that have this nonlinear optical effect. has been done.

Wavelength conversion, especially second harmonic generation based on second-order nonlinear optical effects.
ration.

(hereinafter abbreviated as SHG), the conventionally known lithium niobate (LiNbOx) and potassium dihydrogen phosphate (KD
It has been pointed out that organic compounds may have an order of magnitude higher performance than inorganic materials such as P).

(For example, "Organic Nonlinear Optical Materials," Masao Kato, Supervised by Nakanishihe Department, CMC Co., Ltd., published in 1985) The origin of the nonlinearity of organic compounds is electrons within the molecule, and the second-order nonlinear molecular polarizability β becomes especially large when it has both an electron-donating group and an electron-withdrawing group.

However, as typified by p-nitroaniline, even if the nonlinear polarization at the molecular level is large, there are many compounds that do not exhibit total<SHG in the crystalline state, or have a small -C value of SHG. This is due to the fact that the molecular arrangement of highly polar organic crystals tends to have inversion symmetry.

In addition, research into optical recording media is being actively conducted in response to demands for larger capacity and higher density information recording media, but since the recording density of these optical recording media depends on the wavelength of the light source (
(The recording density limit increases in inverse proportion to the square of the light source wavelength as the light source wavelength becomes shorter), and there are great expectations for wavelength conversion elements to obtain shorter wavelength light sources.

1. However, known compounds with high SHG activity, such as 2-methyl-4-nitroaniline and ■nitroaniline, are yellow in color and have low transmittance at short visible absorption wavelengths. This is disadvantageous for generating shortwave light through wavelength conversion. Therefore, a nonlinear optical material is desired that has high transmittance in the visible region, particularly in short-wavelength light.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a novel organic nonlinear optical material that is difficult to exhibit inversion symmetry in a bulk state such as a crystal or thin film, has virtually no absorption in the visible region, and exhibits high nonlinear optical effects. .

[Structure of the invention]

The above object of the present invention was achieved by using a compound represented by the following general formula [I].

General formula (1) In the formula, D represents an electron donating group and C represents a monovalent organic group.飴 represents an integer of 1 to 3, n represents an integer of O to 3, and when n is 2 or more, a plurality of C's may be the same or different, and may be connected to each other to form a condensed ring.

The present invention will be explained in more detail below.

In the above general formula CI), the electron-donating group represented by D is a halogen atom or one with Hammett's σp<0, such as an amino group, a substituted amino group (methylamino, dimethylamino, L-2- Hydroxymethyl-1-
pyrrolidinyl, etc.), hydroxyl groups, alkoxy groups (methoxy, ethoxy, but-1-oxy, etc.), alkyl groups (methyl, ethyl, propyl, etc.), and the like. D is preferably an amino group, a substituted amino group, a hydroxyl group, or an alkoxy group, and the total number of carbon atoms of the groups having carbon atoms is preferably 3 or less, and more preferably a hydroxyl group or an alkoxy group.

The substitution position of D is preferably the para position of the carboxyl group of benzoic acid.

The monovalent organic group represented by C may be either an electron-donating group or an electron-withdrawing group and is not particularly limited, but a group that does not significantly affect the K-electron conjugated system is preferred.

Examples of the condensed ring formed by bonding adjacent Cs when n is 2 include 7talene, anthracene, indole, quinoline, benzimidazole, and the like. m is preferably 1, and n is preferably O.

Specific examples of compounds preferably used in the present invention are shown below, but the invention is not limited thereto.

Compound Examples These compounds can be easily synthesized by conventionally known methods.

For example, carboxyl groups can be introduced by hydrolysis of cyanobenzene derivatives, oxidation of benzaldehyde derivatives, Kolbe reaction, etc., and conversely, methods for introducing electron-donating groups into benzoic acid derivatives are also generally known. In addition, some of the compounds are commercially available as reagents (for example, manufactured by Kanto Kagaku, Tokyo Kasei, Wako Pure Chemical, and Aldrich).

Typical synthesis examples are shown below.

Synthesis Example 1 (Synthesis of Compound Example 1) 90+a12 10% aqueous sodium hydroxide solution and 4p)
To a solution I of mQ dimethyl sulfate dissolved in 30 methanol, 30 g of gallic acid was added, and an additional 270 m (2
A 10% aqueous sodium hydroxide solution was added dropwise. Approximately 80℃
After reacting for 1 hour, the mixture was gradually cooled while stirring, and the precipitated solid was collected by filtration, washed with water, and dried. Recrystallization from ethanol gave 20 g of white crystals. Both NMR%FD-Mass support the structure of 2-hydroxy-3,4-dimethoxybenzoic acid.

Synthesis Example 2 (Synthesis of Compound Example 5) 40g of 5-amino-1-su7tol was dissolved in 40012 ethanol, and 16.5g of sodium hydroxide was dissolved in 400ml of water (2) under a nitrogen stream. added.

After concentrating under reduced pressure, dichlorobenzene (30 (1 m)) and carbon dioxide were added to 55 atm in an autoclave, heated to 160°C, and reacted for 10 hours. After distilling off the solvent under reduced pressure, it was extracted with ethyl acetate. It was concentrated under reduced pressure and recrystallized from ethyl acetate to obtain 33 g of the desired crystal of 5-amino-1-hydroxy-2-naphthoic acid. NMR and FD.
-The structure was confirmed by Mass.

The compounds of the present invention can be produced in a variety of nonlinear forms, including single crystals, powders, solutions, thin films deposited on supports (Langmeer-Blodgett films, vaporized films, etc.), or blended into polymers or liquid crystal molecules. It can be used as an optical material. It is also possible to use the compound of the present invention pendantly, as a clathrate compound, or as an adduct.

The nonlinear optical material of the present invention can also be processed into a fiber or flat plate-shaped leading waveguide.

〔Effect of the invention〕

According to the present invention, it is possible to provide an organic nonlinear optical material that has substantially no absorption in the visible region, is unlikely to exhibit inversion symmetry when used, and can obtain a high 5) IG.

〔Example〕

Hereinafter, the embodiments of the present invention will be explained in detail with reference to Examples, but the embodiments of the present invention are not limited thereto.

Example 1 A commonly used powder method (S, Kurtz, T, T, Perry; J, Ap
pl, Phys, 39.3798 (1968)).

T-ko.

The light source was a Q-switched Nd:YAG laser (Quantel Inn, USA) with a beam diameter of 2+ss, repetition rate of 10pps, pulse width of 10ns, and pulse energy of 20+aJ.
ternationa1 YG660A, wavelength 101
064n was used to fill a glass cell and irradiate the powder sample.The generated SHG light (green light of 532 mm) was separated into spectra using a filter and a monochromator, and detected with a photomultiplier tube to detect urea. The relative value when set to 1 was calculated.

Furthermore, absorption in the visible region in methanol was also measured. The results are also shown in Table 1.

Table 1 As is clear from Table 1, the compound of the present invention has strong SHG intensity and virtually no visible absorption, so it is an excellent nonlinear optical material that can be used for shorter wavelength light.Example 2 As a light source, the beam diameter is 21111. Repetition 10pps
, a dye laser with a pulse intensity of 7 ns and a pulse energy of 20 mJ (5pectra Physics PDL, USA)
-2; LDS-867, wavelength 862 nm) was used to measure the blue light intensity at 431 nm in the same manner as in Example 1,
Relative values were determined when 2-methyl-4-nitroaniline (MNA) was taken as 1. The results are shown in Table 2.

Table 2 As is clear from Table 2, the compound of the present invention is a nonlinear optical material that is particularly excellent in generating blue light.

Claims (1)

[Claims] A nonlinear optical material comprising a compound represented by the following general formula [I]. General formula [I] ▲Mathematical formulas, chemical formulas, tables, etc. are available▼ [In the formula, D represents an electron-donating group and C represents a monovalent organic group. m represents an integer of 1 to 3, n represents an integer of 0 to 3, and when n is 2 or more, the plurality of C's may be the same or different, and may be connected to each other to form a condensed ring. ]