JPS6259934A - Nonlinear optical organic material - Google Patents

Abstract

PURPOSE:To obtain the titled material having a large 2nd high frequency generating capacity (SHG) and a high stability at a room temp. and a large-sized monocrystal by incorporating a specific org. compd. to the titled material. CONSTITUTION:The titled material comprises a 2-amino fluorenone shown by formula I or a 4-amino-4'-nitrobiphenyl shown by formula II. The prescribed compds. may grow to the large monocrystal by a slow evaporation method. The prescribed compds. has a SHG larger than that of an urea by few times and has a good stability at the room temp. and may be easily grown to the large monocrystal. Thus, the titled material is used for materials of an optical wavelength conversion element, an optical shutter, a high switching element, a optical logical gate and an phototransistor.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a punching material for nonlinear optics.

The present invention relates to an organic material for nonlinear optics consisting of 2-aminofluorene and 4-amino-4'-nitrobiphenyl.

[Conventional technology]

Nonlinear optical materials have been widely used as optical wavelength conversion elements, optical shutters, etc. in laser oscillation devices and the like.

Recently, nonlinear optical materials have been used for high-speed optical switching devices,
It is attracting attention from various related fields as an essential material for realizing optical computers such as optical logic gates and optical transistors, and the search for new materials is actively underway.

Currently, potassium dihydrogen phosphate (KDP) and lithium niobate (L 1Nbo3) are used as materials for nonlinear optics.
Inorganic crystals such as urea are in practical use.

Organic crystals such as 4-nitroaniline (PNA) and 2-methyl-4-nitroaniline (MNA) are also known.

IEEE Spectrum
ram) June (1981), pages 26-33.

In general, organic crystals have larger nonlinear optical effects than inorganic crystals, and the coefficients of second harmonic generation (SHG) and third harmonic generation (THG) are about 10 to 100 times higher. The light response speed is also said to be about 1000 times shorter.
It is also recognized that the threshold for photodamage is large. Furthermore, it is known that SHG does not appear in a single crystal that waits for a center of symmetry as a feature of even-order nonlinear optical effects.

[Problem that the invention seeks to solve]

Among the nonlinear optical effects required for nonlinear optical materials, SHG is regarded as a basic technology for wavelength conversion because of its high conversion efficiency. In addition, if SHG is large, the second-order nonlinear optical constant is large, so a material with large SHG is required as a nonlinear optical effect material.Also, as mentioned above, organic crystals generally have nonlinear optical effects. However, it is required to be stable at room temperature.

Among conventionally known organic crystals, MNA has SHG activity because it is a crystal without a center of symmetry, and its strength is 22 times that of urea. It has the disadvantage of not being accurate.

In addition, large single crystals of urea are easily obtained.

It has the disadvantage of low SHG activity (and poor moisture resistance).

As mentioned above, an organic crystal that is stable at room temperature and has high SHG activity because it is a single crystal without a center of symmetry is currently in greatest demand.

On the other hand, for practical use as a material for nonlinear optics, it is desirable to have a single crystal as large as possible.

There is a strong demand for the development of plate materials for nonlinear optics that can be easily grown into large single crystals.

[Means to solve the problem]

The present inventor has discovered that because it is a single crystal without a center of symmetry, it has high SHG activity and is stable at room temperature.
In addition, the present invention was arrived at as a result of various studies in order to obtain an organic crystal that can be easily grown into a large single crystal if necessary.

That is, the present invention is an organic material for nonlinear optics comprising 2-aminofluorene represented by the formula 2 and 4-amino-4'-nitrofluorene represented by the formula 2.

[For production]

First of all, the most important points in the present invention are 1.
Since -aminofluorene and 4-amino-4'=nitrobiphenyl are single crystals that do not have a center of symmetry, they exhibit several times the SHG activity of urea and are stable at room temperature.

2-aminofluorene and 4-amino-4 according to the present invention
'-Nitrobiphenyl was produced in powder form using a Nd:YAG laser (wavelength = 1,064 μm, output 3 mJ/pulse).
Generation of second harmonics (SHG) when measured by irradiation of t,
, it emits green light with a wavelength (532 μm) that is half the wavelength of the incident light.

Furthermore, 2-aminofluorene and 4-amino-4'-nitrobiphenyl according to the present invention can be grown into a single crystal on the order of mm.

Next, a method for synthesizing 2-aminofluorene and 4-amino-4'-nitrobiphenyl according to the present invention will be described.

2-aminofluorene according to the present invention can be obtained by reducing 2-nitrofluorene obtained by reacting fluorene in concentrated nitric acid-acetic acid with hydrazine hydrate in ethanol in the presence of palladium charcoal. Can be done.

As a reducing agent for 2-nitrofluorene, zinc, tin, tin chloride (11), etc. can also be used, and in this case, an acid such as hydrochloric acid may be added to the solvent.

The 4-amino-4'-nitrobiphenyl according to the present invention is 4
It can be obtained by reducing 4,4'-dinitrobiphenyl obtained by reacting -9-donitrobenzene in the presence of copper with sodium sulfide in a mixed solvent such as methanol-benzene.

4.4'-dinitrobiphenyl can also be obtained by reacting 4-nitrobiphenyl with concentrated nitric acid and concentrated sulfuric acid, concentrated nitric acid and m-acid, and the like.

2-aminofluorene and 4-amino-4'-nitrobiphenyl can be used in powder form or.

Even when made into a large single crystal, it exhibits excellent SHG activity.

2-aminofluorene and 4-amino-4 according to the present invention
'-Ditrobiphenyl can be grown into a large single crystal by slow evaporation or the like. When growing a large single crystal, solvents with high solubility such as acetone, tetrahedron, and chloroform are used.

〔Example〕

Next, the present invention will be explained in detail with reference to examples.

In addition, the SHG activity in the Examples is expressed as a magnification based on urea.

<Synthesis of 2-aminofluorene> 16.6 g (0.1 mol) of fluorene in 140 ml
of acetic acid and heated while stirring with a mechanical stirrer to dissolve, and then raise the temperature to 60-65°C.

Add 160 ml of concentrated nitric acid little by little. The temperature of the reaction solution will rise, but do not exceed 80°C.

Also, stir vigorously during this time. After that, the temperature of the reaction solution was 6
Filter the solid that precipitates when the temperature drops to about 0 m,
When the obtained solid was washed several times with acetic acid and water and then dried, 14.3 g of 2-nitrofluorene was obtained.

2-nitrofluorene thus obtained 10.5
Add 5 g (50 mmol) to □ml of 9596 ethanol solution B and bring to 50°C. Add 50 mg of palladium charcoal, stir, and add 6 ml of hydrazine hydrate over 20 minutes. Thereafter, 50 mg of palladium charcoal was further added, the temperature was raised to such an extent that the solvent was slightly refluxed, and the mixture was stirred for 1 hour. The reaction solution was filtered through Celite, and the solvent was removed under reduced pressure until one reaction solution amounted to about 15 ml. 80 ml of hot water is added to this concentrated solution, and when the mixture is cooled to 0° C., a white solid is precipitated. This solid was filtered, washed with water, and dried to obtain 6.88 g of 2-aminofluorene.

Elemental analysis value (as C1s H3N) Calculated value: C86,15, H6,12, H7,73 Actual value: C86,27, H6,19, H7,54 <Synthesis of 4-amino-4'-nitrobiphenyl> Add 40 g of sand to 24.9 g (0.1 mmof) of 4-iodonitrobenzene.
g, and heated to 220°C and stirred. Add 26g of copper powder to it over about 1.5 hours. After stirring for 2.5 hours while maintaining the temperature, the two reactants were dissolved in heated ethanol, filtered, and the solvent was removed from the mouth liquid under reduced pressure to obtain a solid. When this solid was separated and purified by silica gel column chromatography and recrystallized from ethanol, 4. 4'
-3.90 g of dinitrobiphenyl were obtained.

2.44 g (10 mmol) of 4,4'-dinitrobiphenyl thus obtained and 2.4 g of sodium hydrosulfide (7096) were added to 150 ml of a mixed solvent of methanol-benzene (1:2). Heat to reflux for 20 minutes. The solvent of the reaction solution was removed under reduced pressure.

The obtained solid was separated and purified using a silica gel column to obtain 1.40 g of 4-amino-4'-nitrobiphenyl.

Elemental analysis value (CI281°N20-) Calculated value:
C67,28, H4,71, N13.08 Actual value: C
67,40, H4,82, N12.95 <SHG activity of microcrystalline powder> Example 1 2-aminofluorene was compacted into a pellet shape using a tablet molding machine, and then Nd:YAG laser light (wavelength = 1.064 μm, output = 3 mJ/pulse), green scattered light of 532 μm due to SHG was generated. When the intensity is measured using a photoelectric conversion element, 1 of urea
It was about 00 times.

Example 2 4-amino-4'-nitrobiphenyl was tested for SHG activity in the same manner as in Example 1.

It was about 3 times that of urea.

<Single crystallization of microcrystalline powder> Reference Example 1 200 mg of 2-aminofluorene was dissolved in ethanol to prepare a saturated solution. By leaving this at room temperature and gradually evaporating the solvent, it was made into a size of 1 mm x 1 mm in a few days.
A single crystal with a size of about 3 mm was obtained. This crystal was stable for a long time at room temperature, and phase-matched laser light of 172 wavelengths (532 nm) was obtained by irradiation with Nd:YAG laser light.

Reference Example 2 Using 4-amino-4'-nitrobiphenyl, Reference Example 1
A single crystal of approximately 1 mm x 1 mm x 2 mm was obtained in the same manner as above.

This crystal expressed SHG activity as in Reference Example 1 and was stable at room temperature.

〔effect〕

2-aminofluorene and 4-amino-4 according to the present invention
As shown in the previous example, the organic material for nonlinear optics consisting of '-nitrobiphenyl has a SHG several times larger than that of urea, and is stable at room temperature. As expected, it is easy to grow into large single crystals,
Therefore, it is suitable as a material for optical wavelength conversion elements, optical shutters, high-speed optical switching elements, optical logic gates, optical transistors, and the like.

Claims (1)

[Claims] 1. An organic material for nonlinear optics consisting of 2-aminofluorene represented by the formula ▲ Numerical formula, chemical formula, table, etc. ▼. 2. An organic material for nonlinear optics consisting of 4-amino-4'-nitrobiphenyl represented by the formula ▲Mathematical formulas, chemical formulas, tables, etc.▼.