JPH02935A - Nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain a high nonlinear optical effect by using a specific compd. so that inverse symmetry is hardly obtainable in a bulk state such as crystal or thin film and the material has substantially no absorption in a visible region. CONSTITUTION:The compd. expressed by formula I is used as this material. In formula I, D denotes an electron-donating group; C denotes a monovalent org. group; R denotes a hydrogen atom, alkyl group, aryl group or heterocyclic group; (m) denotes 1-3 integer; (n) denotes 0-3 integer. This compd. is usable as the nonlinear optical material in various forms such as single crystal, powder, soln. the thin film (Langmuir-Blodgett film, vapor deposited film, etc.) deposited on a base or the form of blending the same into a polymer or liquid crystal molecules. The material which has substantially no absorption in the visible region is obtd. and the inverse symmetry is hardly obtainable in the form of use. In addition, high second harmonic waves are generatable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a nonlinear optical element and a nonlinear optical material suitable for use in an optical device including the element.

[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 (LiNb0s) 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", edited by Masao Kato and Hebe Nakanishi, published by CMC Co., Ltd., 1985) The origin of the nonlinearity of organic compounds is the intramolecular π electrons, and the second-order nonlinear molecular polarizability β becomes particularly 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 that do not exhibit total<SHG in the crystalline state, or even if they do, the SHG is small. 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.

However, known compounds with high SHG activity are colored yellow, such as 2-methyl-4-nitroaniline, ■-nitroaniline, etc., and therefore have low transmittance for short visible absorption wavelengths, resulting in wavelength conversion. This is disadvantageous for generating shortwave light. 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 such as a crystal or thin film that exhibits inversion symmetry in the Baltic state, has virtually no absorption in the visible region, and exhibits high nonlinear optical effects. be.

[Structure of the invention]

The above object of the present invention was achieved by using a compound represented by the following general formula CI).

General formula CI) In the formula, D represents an electron donating group, C represents a monovalent organic group, and R represents a hydrogen atom, a substituted or unsubstituted alkyl group, an aryl group, or a heterocyclic group. m 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 [I], the electron donating group represented by D is halogen'/, atom or Hammett's σp<0
For example, amino groups, substituted amino groups (methylamino, dimethylamino, L-2-hydroxymethyl-
1-pyrrolidinyl, etc.), a hydroxyl group, an alkoxy group (methoxy, ethoxy, butoxy, etc.), an alkyl group (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 rose position of the sulfamoyl group of benzenesulfonamide.

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 π-electron conjugated system is preferable.

The substituted or unsubstituted alkyl group represented by R is
Examples include groups such as methyl, ethyl, l-propyl, t-butyl, chloromethyl, trifluoromethyl, benzyl, and methoxycarbonylmethyl.

The total number of carbon atoms in the alkyl groups is preferably 4 or less. The substituted or unsubstituted aryl group represented by R is
It is a phenyl group or a naphthyl group, preferably a phenyl group substituted with an electron-withdrawing group having Hammett's σp>0.2. The substituted or unsubstituted heterocyclic group represented by R is preferably a 5- to 6-membered heterocyclic group, and the heterocycle may have a substituent and may be further fused with a carbon ring. .

When n is 2, examples of the condensed ring formed by bonding adjacent C's to each other include naphthalene, anthracene, indole, quinoline, benzimidazole and the like. Preferably m is 1, and n is preferably O.

Specific examples of compounds preferably used in the present invention are shown below. :@Not determined.

Compound example NHshiυshiH1 CH.

These compounds can be easily synthesized by conventionally known methods.

For example, the introduction of a sulfamoyl group is generally obtained by converting a benzenesulfonic acid derivative into an acid halide and further reacting it with ammonia, an alkylamine, an arylamine, etc.

The electron-donating group represented by D is preferably introduced after the introduction of the sulfamoyl group, but an alkokene group, a tertiary amine, etc. can be introduced even before the introduction of the sulfamoyl group.

In addition, some of the compounds are available as commercially available reagents (eg, Kanto Kagaku, Tokyo Kasei, Wako Tsumugi, Aldrich products).

Typical synthesis examples are shown below.

Synthesis Example (Synthesis of Compound Example 1) 30g of p-aminobenzoic acid was dissolved in 200ml of pyridine, 48g of p-nitrobenzenesulfonyl chloride was added, and the mixture was reacted at about 60°C for 3 hours. The reaction solution was poured into diluted hydrochloric acid, and the precipitated crystals were collected by filtration and dried.

Add the total amount to 100a12 tetrahydrofuran and 300mQ
was dissolved in a mixed solution of ethanol, and 5 g of Pd-C catalyst was added thereto for hydrogenation. After the reduction, the Pd-C catalyst is filtered off, the solvent is distilled off, and the target l-amino-4-(4-carboxyphenyl)sul7 is recrystallized from ethanol.
56 g of amoylbenzene crystals were obtained. Melting point 209~2
The structure was confirmed by 10°Co FD-Mass and NMR.

The compounds of the present invention can be used as nonlinear optical materials in various forms, such as single crystals, powders, solutions, thin films deposited on supports (Langmeer-Prodgett films, vapor-deposited films, etc.), or blended into polymers or liquid crystal molecules. It can be used as It is also possible to pendant the compound of the present invention to a polymer, or use it as an inclusion compound or adduct.

The nonlinear optical material of the present invention can also be processed into a fiber or flat optical 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 difficult to exhibit inversion symmetry when used, and can provide high SHG.

〔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 Powder method commonly used to determine SHG effect (S, Kurtz, T, T, Perry; J, Ap
Compounds of the present invention were evaluated using the following method.

As a light source, the beam diameter is 2111111. Repeat 10pp
s, pulse width 10 ns, pulse energy 20 mJ Q-switch Nd: YAG laser (Quantel, USA)
The SHG light (532 nm
The green light) was spectrally analyzed using a filter and monochromator, and detected using a photomultiplier tube, and the relative value when urea was taken as 1 was determined.

Furthermore, the absorption in the visible region in methanol is also measured.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 compound that can be used for even shorter wavelength light. It turns out that it is an optical material.

Example 2 A dye laser (PDL-2 from Pectra Physics, USA) with a beam diameter of 2 mm, a repetition rate of 1 opps, a pulse of 17 ns, and a pulse energy of 20 mJ was used as a light source.
, LDS-867, wavelength 862 nm), the intensity of blue light at 431 nm was measured in the same manner as in Example 1, and 2-
Relative values were determined when methyl-4-nitroaniline (MNA) was taken as 1. 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] ▲ Numerical formulas, chemical formulas, tables, etc. are available▼ [In the formula, D is an electron-donating group, C is a monovalent organic group, R is a hydrogen atom, a substituted or unsubstituted alkyl group, an aryl group, or Represents a heterocyclic group. 1 represents an integer of 1 to 3, n represents an integer of 0 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. ]