JPH0455400A - Production of organic single crystal - Google Patents

Abstract

PURPOSE:To improve reproducibility by putting a seed crystal of 3-methyl-4- nitropyridine-1-oxide in a meshy vessel and suspending this vessel in a soln. CONSTITUTION:A soln. prepd. by dissolving 3-methyl-4-nitropyridine-1-oxide (POM) in a polar org. solvent such as methyl acetate is poured into a thick glass vessel 2 set in a constant-temp. water bath 6. A fine seed crystal 8 of POM with a well exposed growth face is put in a stainless basket 7 and this basket 7 is suspended from the top of the vessel 2 so that it is positioned at the nearly central part of the vessel 2. A glass plate 4 for controlling the rate of evaporation is fixed on the top of the vessel 2 with a weight 5, the area of the opening of the vessel 2 is regulated with the plate 4 and the solvent is slowly evaporated to obtain a transparent org. single crystal.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing an organic single crystal, and in particular, an organic single crystal useful for producing a nonlinear optical element using POM, which is an organic nonlinear optical material. The present invention relates to a manufacturing method.

(Prior art) Among the many types of nonlinear optical phenomena, second harmonic generation (S
Since HG) can easily shorten the wavelength of laser light by half, research is underway in the field of optoelectronics with the aim of applying it to optical recording and short wavelength laser light sources such as light sources for optical disks and light sources for laser printers. being done.

Recently, organic crystals with a π-electron conjugated system have extremely high second-order nonlinear optical properties, and conventional KDP (KH2PO4
) and LN (LiNb03), which are expected to be about 10 to 103 times more efficient than well-known inorganic crystals, and much research has been carried out. These are usually referred to as practical single crystals with second-order nonlinear optical effects. Practical organic single crystal materials with such second-order nonlinear optical effects include EVA, the above-mentioned POM, 2-methyl-4-nitroaniline, 4'-nitrobenzylidene-8-7cetamin-4-methoxyaniline (CG OM, Tech
nicalDigest, 1989.284-287)
, dicyanovinylanisole (CGOMe Techn
ical Digest.

1989, 229-288), 8,5-dimethyl-1
-(4-nitrophenyl)pyrazole (CGOM.

Technical Digest, 1989.256
-258), 4-promo 4'-methoxychalcone (C
L.E.O.

1989.276), (-)2-(α-methylbenzylamino)-5-nitropyridine (SP I E, vo
l.

971, 38.1989), N-(4-nitrophenyl)-(L)-prolinol (J, Chem, Phy
s, 81°1984.4160), 4-(N,N-dimethylamino)-3-acytamide nitrobenzene (A
p p 1. Phys.

Lett, 51.1987.1484), etc. are known.

Among these, typical methods for growing POM single crystals include a gas phase method, a melt method, and a solution method.

Among the above growth methods, the vapor phase method is capable of growing thin film crystals, but it is not suitable for growing bulk crystals.Also, when growing crystals using the melting method, POM decomposes rapidly in the molten state, making it difficult to grow crystals. It is possible.

On the other hand, the solution method, which grows Sibulk single crystals by evaporating or cooling the solvent, usually takes a long time to grow, around 80 days, but avoids the above-mentioned drawbacks of the gas phase method and melt method. This is an industrially important method.

(Problems to be Solved by the Invention) However, in growing POM single crystals using the conventional solution method, it has not been possible to obtain high-quality POM single crystals with good reproducibility.

In general, the larger the nonlinear optical constant of organic nonlinear optical materials, the more anisotropic their molecular and crystal forms tend to be, making it difficult to control crystal growth. It is desired to develop a method that can efficiently produce bulk crystals with a large . This means that highly reproducible crystal habit control is an unavoidable problem in crystal growth methods. In this regard, in order to control the crystal habit of an organic single crystal in the solution method, it is necessary to actually grow the crystal using an organic solvent or a mixed solvent thereof, observe the generated crystal habit, and select a solvent suitable for the purpose. Although the procedure is commonly followed, it has been extremely difficult to industrially produce bulk single crystals with good yields.

On the other hand, in order to obtain high-quality organic single crystals using the solution method, it is essential to control the generation of seeds that serve as nuclei for crystal growth. In other words, when two or more nuclei (seed crystals) overlap and grow, it can cause countless crystal defects and cracks, so we reproduce the promotion of crystal growth by a single nucleus (seed crystal). It is necessary to do it in a good manner, but 2
Nuclei control to prevent the generation of more than one nucleus is not only affected by the evaporation rate of the solvent, the cooling rate of the solution, and the temperature environment around the device, but also the shape of the growth vessel itself and the placement of seed crystals. This was extremely difficult as it was greatly affected by the state of affairs.

(Means for solving problem II) The present invention was made under such circumstances,
In order to produce bulk single crystals of POMs of good quality with good reproducibility using a solution method, we particularly aim to provide a method for nuclear control.

The method for producing POM single crystal, which is an organic nonlinear optical material, in the present invention is to control the seed crystal that serves as the nucleus with good reproducibility.For this purpose, a mesh cage made of stainless steel is made, and a sufficient amount of material is placed in the cage in advance. A glass plate that has been cleaned previously is laid out, a seed crystal is placed in the center of the plate, and the plate is suspended from the top of the growth container containing a saturated solution of POM, approximately in the center of the growth container. Especially, PO
It has been discovered that a bulk single crystal of M can be grown from a single nucleus, and the present invention has been achieved as a method to solve this problem.

Thus, it has been concluded that according to the present invention, a POM bulk single crystal of good quality can be grown simply and with good reproducibility.

(Example) FIG. 1 shows the shape of stainless steel mesh knots used in the present invention, and FIG. 2 shows the growth tank.

18.5 g of 8-methyl-4nitropyridine-1-oxide (POM) was dissolved in 450 ml of methyl acetate solvent, and the solution was heated to a water temperature of 80°C ± 0.1°C as shown in Figure 2.
A capacity of 500 m1 installed in a constant temperature water tank 6 controlled by
The mixture was poured into a glass container 2 with a thick wall. In the figure, 1 is constant temperature water, 8
indicates a solution.

Next, put a fine seed crystal (8 in Figure 2) with a well-protruding growth surface into the basket shown in Figure 1 (7 in Figure 2), and place the basket from the top of the glass container in Figure 2. Hang it so that it is almost in the center of the container.

In this state, the evaporation rate control glass plate 4 was fixed to the opening of the glass container with a weight 5, the width of the opening of the glass container 2 was adjusted, and the solvent was gradually evaporated in this state. However, on the 20th day after the start of evaporation, the height was 22 mm and the width was 22 mm.
A transparent bulk single crystal with a thickness of 8.4 mm was obtained.

When the obtained bulk single crystal was evaluated using an X-ray diffraction device, X-ray analysis showed that the top surface of the crystal was clean (Zoo).
) surface reflection was obtained. (FIG. 3) The solvent used in this example is the above-mentioned methyl acetate, but any polar organic solvent such as ethyl acetate or dichloromethane may be used. Further, the manufacturing method of the present invention can be used if the material is a second-order nonlinear optical material and a bulk single crystal can be obtained by a solvent evaporation method.

(Effects of the Invention) According to the method for producing an organic single crystal of the present invention, a high-quality bulk single crystal of POM can be produced with good reproducibility using an extremely simple device configuration. Furthermore, by increasing the size of the growth container, it is also possible to obtain a bulk single crystal that is larger than ever before.

Therefore, the method for producing an organic single crystal of the present invention is extremely effective as a method for producing F'OM.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the external shape of a stainless steel mesh cage, FIG. 2 is a schematic diagram of the single crystal growth apparatus used in the present invention, and FIG. 3 is a diagram showing the POM single crystal obtained by the present invention. crystal, (
100) plane. 1. Constant temperature water 2. Glass container 8. Solution 4, glass plate 5. Omo v6. Constant temperature water tank 7, basket 81 seed crystal

Claims (1)

[Claims] 1,3-methyl-4nitropyridine-1-oxide (
When the solvent is evaporated from a polar solvent solution of POM (hereinafter referred to as POM) and a single crystal of POM is grown in the solution, a seed crystal of POM is placed in a net-shaped container, and the container is suspended in the solution. Characteristic method for producing organic single crystals.