JPH071360B2 - Organic nonlinear optical material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an organic optical nonlinear optical material having a large optical nonlinear effect.

(Prior Art) Conventionally, a dielectric crystal such as LiNbO ₃ has been representatively used as a material of this type, but a light source having a very large power is required to exhibit a nonlinear optical effect, and a semiconductor laser is used. However, there is a drawback in that a nonlinear optical effect cannot be freely expressed using a low-output light source such as. On the other hand, as an organic material having a large nonlinear optical effect, for example, 2-
Compounds such as methyl-4-nitroaniline (hereinafter abbreviated as MNA) have been known.

(Problems to be solved by the invention) However, when a large bulk single crystal is to be obtained from a melt, it is difficult to obtain a large single crystal by thermal decomposition or the like with a conventionally known material such as MNA. ,Also
It has been desired to develop a material having a nonlinear optical effect that is even larger than that of MNA.

The present invention is a group of compounds proposed to solve the drawbacks of these conventional materials, and an object thereof is to provide a material for a device to which a nonlinear optical effect is applied in the fields of optical communication and optical information processing.

(Means for Solving Problems) The present invention will be outlined. The present invention relates to an organic nonlinear optical material, wherein the organic compound in the organic compound-based nonlinear optical material has the following general formula I: (In the formula, X represents a bicyclo ring or a tricyclo ring, and π
Represents a π-conjugated aromatic ring such as a benzene ring, a pyridine ring, or a pyrimidine ring).

Since the organic optical nonlinear optical material according to the present invention is composed of a bulky bicyclo ring or tricyclo ring among donors and acceptors bound to a π-conjugated system that produces an optical nonlinear light effect, In addition to the hydrogen bonding effect based on the bonding hydrogen, it is possible to exhibit a large second-order nonlinear optical effect without forming a crystal structure with inversion symmetry.

Here, the group X is adamantane Norbornane Norad amantan Tricyclo (5.2.1.0 ^{2 · 6)} decane Bicyclo (3.2.1) octane Bicyclo (3.3.0) octane Bicyclo (2.2.1) -2-heptene norbornene Bicyclo (2.2.1) hepta-2,5-diene Such as bicyclo ring and tricyclo ring. Usually, the desired organic optical nonlinear optical material can be obtained by using these bicyclo ring and tricyclo ring amine compounds as raw materials.
Further, the introduction of a substituent at a position other than the amino site of these cyclo rings gives a good effect as in the case of non-substitution, as long as it does not bring about an inverted symmetric structure in the obtained crystal. Examples of such a substituent include an alkyl group such as a methyl group, an alkoxy group such as a methoxy group, a hydroxyl group, and a halogen. Furthermore, a nitro moiety of a π-conjugated aromatic ring such as a benzene ring, a pyridine ring, or a pyrimidine ring represented by π,
By introducing a substituent at a position other than the amine site, it is possible to obtain a larger non-linear optical effect and further improve the crystallinity. Examples of such a substituent include halogens such as chlorine, an acetamide group, a hydrogen-bonding substituent such as a hydroxyl group, an alkyl group such as a methyl group and a methoxy group, and an alkoxy group.

On the other hand, the Britzmann method, which has been reported to grow large single crystals, is a single crystal growing method from a melt,
This method is also applicable to adamantane amino-5-nitropyridine (hereinafter abbreviated as AANP). An AANP single crystal was actually grown by the following steps. FIG. 1 is a schematic cross-sectional view of the AANP single crystal growing furnace according to the present invention. 1 is a core tube, 2 is an upper heater, 3 is a lower heater, 4 is a crystal growing glass ampoule, 5 is a single crystal part of AANP, 6 is a melt part of AANP, and 7 is a crystal pulling system for lowering 4. is there.

Hereinafter, production examples of the compound represented by the general formula I will be specifically described, but the present invention is not limited thereto.

Production Example 1 Synthesis of 2-adamantaneamino-5-nitropyridine (AANP) 2-Chloro-5-nitropyridine (10 mmol) and 1-adamantanamine (11 mmol) are melted in triethylamine and heated under reflux for one day under a nitrogen atmosphere to obtain a reaction product. After the reaction solution was cooled to room temperature to completely precipitate the product, this was separated by filtration and washed with cold ethanol. Recrystallization using benzene gave granular crystals.

Production Example 2 Synthesis of 4 (3-noradamantaneamino) nitrobenzene (hereinafter abbreviated as NAANB) 4-Chloronitrobenzene (10 mmol) and 3-noradamantanamine (11 mmol) are dissolved in dimethyl sulfoxide, and the mixture is heated under reflux in the presence of potassium carbonate for one day to obtain a reaction product. After cooling and washing in the same manner as in Production Example 1, recrystallization was performed using benzene to obtain granular crystals.

Production Examples 3 to 5 In the same manner as in Production Example 1, 3-noradamantanamine, 2-
Adamantane amine-hydrochloride and 2-norbornane amine-hydrochloride were used as raw materials to synthesize corresponding amino nitropyridines (abbreviated as NAANP, 2AANP and NANP, respectively) to obtain crystals.

Production Example 6 Similar to Production Example 2, 1-adamantanamine was used as a raw material and the corresponding aminonitrobenzene (abbreviated as AANB) was used.
Synthesized to obtain crystals.

Production Example 7 Synthesis of 2-adamantaneamino-5-nitropyrimidine (abbreviated as AANPY) AANPY was synthesized by the same method as in Production Example 1 except that 2-chloro-5-nitropyridine was used instead of 2-chloro-5-nitropyridine in Production Example 1 to obtain crystals.

Production Examples 8-9 2-chloro-4-nitroaniline and 2-chloronorbornane were heated to reflux in acetone in the presence of NaOH in the same manner as in Production Example 2 except that 3-chloro-4- Norbornane aminonitrobenzene (abbreviated as CNANB)
Was synthesized to obtain crystals.

Further, 3-chloro-4-adamantaneaminonitrobenzene (abbreviated as CAANB) was synthesized by using 1-chloroadamantane by the same method to obtain crystals.

(Examples) Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

Examples 1 to 9 Nonlinear optical properties of the compounds obtained in Production Examples 1 to 9 were measured. The magnitude of the nonlinear optical effect used the powder method established by Kurtz et al. As described below. Nd: YAG laser with a fundamental wavelength of 1.06 μm (10
Hz, 50 MW / cm ² ) as a light source, and after cutting visible light,
The beam condensed by the lens is applied to the microcrystalline powder sample.
The light emitted from the sample was passed through an IR cut filter and a monochromator, and the intensity of the generated second harmonic (SHG) was detected by Fotomaru. The results were evaluated by the ratio with respect to the SHG intensity in the urea microcrystalline powder sample which is a standard sample.
The results are shown in Table 1 below. The results of MNA are also shown as a comparative example.

As shown in Table 1, SHG strength is as large as 200 times that of urea for AANP, 180 times for 2AANP and 160 times for CAANB.
NAANP 150 times, AANPY 90 times, CNANB 60 times, AANB 50
The NAANB is 45 times and the value is much larger than that of the MNA.

Example 10 Using the apparatus shown in FIG. 1, an AANP single crystal was obtained as follows. The second heater in Fig. 1 is the melting point of AANP (16
5 ° C), which is 10 ° C higher than 175 ± 1 ° C, and the heater of 3 is set to 145 ± 1 ° C which is 20 ° C lower than the melting point. First of all, 4
I made a glass growing glass ampoule of
10 g of AANP was enclosed under a nitrogen atmosphere. This ampoule
The inside of the crystal growth furnace shown in FIG. 1 was slowly lowered at 1 mm / hr.
Next, 4 was temporarily stopped at the position of the heater 3 and cooled slowly to room temperature at 5 ° C./hr, and the crystal was taken out. A single crystal is grown almost all over the tube, and the size is 15 mm in diameter and 30 in length.
It was a mm AANP single crystal.

The thermal stability of this single crystal, especially its structural change when heated above its melting point, was investigated by IR and NMR. 20 from melting point 165 ° C
The AANP was allowed to stand at ℃ higher temperature for 24 hours, but there was no structural change. In contrast, MNA has a melting point of 131 ° C to 20 ° C.
When left at a high temperature for 24 hours, the melt had changed to blackish brown and structural changes had occurred. From the above, it was found that AANP is more thermally stable than MNA.

Similarly, with other organic optical nonlinear optical materials according to the present invention, large bulk crystals tend to be obtained.

Further, it has been found that the organic nonlinear optical material group according to the present invention is a material in which a large bulk crystal can be obtained by a recrystallization method from a solvent and a thin film can be easily formed by a usual vacuum deposition method.

(Effects of the Invention) As described above, the compound group according to the present invention has a large nonlinear optical effect, and a large bulk crystal can be obtained. Therefore, a device to which the nonlinear optical effect is applied, such as a wavelength conversion element or an optical modulator, is used. It has an advantage that it can be an important material for constructing an optical switch, an optical bistable element, and the like.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an apparatus for growing an AANP single crystal in the present invention. 1: core tube, 2: upper heater, 3: lower heater, 4: crystal growing glass ampoule, 5: AANP single crystal part, 6: AANP melt part, 7:
Crystal pulling system

Claims (1)

[Claims] 1. An organic compound-based nonlinear optical material, wherein the organic compound has the following general formula I: (In the formula, X represents a bicyclo ring or a tricyclo ring, and π
Represents a π-conjugated aromatic ring), and is an organic nonlinear optical material.