JPH08253399A - Production of dnbb single crystal - Google Patents

Abstract

PURPOSE: To obtain a process which surely produces a DNBB single crystal of high quality by using an effective equipment while avoiding such intrinsic problem on the temperature-changing process that the temperature fluctuation of the solution in the equipment influences the crystal produced. CONSTITUTION: In the production of a single crystal of DNBB represented by the formula from its solution in an organic solvent, DNBB is precipitated in such an environment that the deteriorated components are removed from the solution, while varying the temperature of the solution in the organic solvent periodically in a certain range in the growing tank where the DNBB is precipitated to give the single crystal.

Description

Detailed Description of the Invention

[0001]

This invention relates to 3,9-dinitro-5
The present invention relates to a method for producing a single crystal of a, 6,11a, 12-tetrahydro [1,4] benzoxazino [3,2-b] [1,4] benzoxazine (herein referred to as "DNBB"). The DNBB single crystal has a large second-order nonlinear optical effect, and is preferably used in the fields of optics and information, especially optical communication, optical recording and the like.

[0002]

2. Description of the Related Art DNBB single crystal is disclosed in Japanese Patent Laid-Open No. 1-4538.
It is a high-performance second-order nonlinear optical crystal disclosed in No. 8.
DNBB has a high 2 by using it as a single crystal.
Next, it exerts a nonlinear optical effect. Therefore, it has been desired to establish a method for producing a single crystal of DNBB.

Generally, as a method for producing an organic single crystal, 1) a crystallization solution is prepared using a substance to be crystallized as a solute, and then the solute is re-precipitated from the solution by some method to form a single crystal. Method (hereinafter referred to as a solution method), 2) A method of melting a substance to be crystallized and then lowering the temperature to a temperature below the melting point to obtain a single crystal (hereinafter referred to as a melting method), 3) A substance to be crystallized Is made into a gas phase state by utilizing a phenomenon such as sublimation, and then a single crystal is obtained by solidifying the substance in the gas phase state again (hereinafter referred to as a gas phase method). There are many explanations about these methods. For example, Advanced Crystal Growth, PMDryburgh et al.
edit. 1987, Prentice Hall International (UK) Ltd.
Among them, articles about the melting method are described in p25 to p178, articles about the solution method are described in p221 to p288, and articles about crystal production by a gas phase method are described in p289 to p434. Furthermore, in the same magazine, p179-p
At 220, an article is specifically described regarding a method for producing an organic single crystal.

As described in JP-A-1-45388, DNBB has no melting point and decomposes at around 280 ° C. under normal pressure. Therefore, single crystal production by the melting method cannot be used. Further, the sublimability is low as can be easily imagined from the decomposition temperature, and it is difficult to apply the single crystal production by the vapor phase method. Therefore, single crystal production by the solution method has been applied exclusively.

In the crystal production method by the solution method, it is necessary to make the solution saturated by some method and reprecipitate the solute. The methods are: a) a method of evaporating the solvent in the solution to precipitate the solute (hereinafter referred to as solvent evaporation method), and b) a method of changing the solution temperature to precipitate a solute having a difference in solubility due to temperature change. (Hereinafter referred to as the temperature change method).

Regarding the method for producing a crystal of DNBB using the solvent evaporation method of a), an organic solvent such as a ketone system is used, and
A method for obtaining an NBB single crystal is described in JP-A-1-45388.

In the method for producing a single crystal by the solvent evaporation method, the solvent must be evaporated at a rate suitable for producing the single crystal. However, it is necessary to appropriately combine many factors such as the shape and temperature of the container, the type of solvent, and the atmosphere, and it is extremely difficult to accurately control the evaporation rate of the solvent. Therefore, the solution is in a supersaturated state, and solute precipitation tends to be unstable. In this state, many microcrystals or polycrystals (hereinafter referred to as miscellaneous crystals) are often precipitated from impurities in the solution, scratches on the wall surface of the container, or contaminated portions. Therefore, most of the deposited solutes are consumed for the generation of miscellaneous crystals, and it becomes difficult to obtain a large single crystal. That is, in the method for producing a single crystal of DNBB using the solvent evaporation method, it is difficult to control the evaporation of the solvent, so that it is a serious problem that the reproducibility is poor to obtain a large single crystal.

On the other hand, in the temperature change method of b), the amount of solute deposited can be controlled by controlling the temperature of the solution. Therefore, it is expected that the amount of solute deposited can be controlled relatively easily as compared with the solvent evaporation method. Crystallization by this method is explained in many books, for example, 4th edition Experimental Chemistry Course 2 Basic Operation II
The Chemical Society of Japan Maruzen p354-p364 and RN Hooper, B.
J. McArdle, RSNarangand JNSherwood, Crystal Grow
th, 2nd ed., Ed. B. Pamplin (Pergamon, Oxford, 1975) p.
For example, the case of using the solvent evaporation method for single crystallization of organic materials and detailed description of the method are given in 395 and the like.

The use of the temperature change method in DNBB is described in JP-A-5-186093. However, in the method described here, since the DNBB solute is deposited by changing the solution temperature, it is difficult to precisely control the deposition amount of the solute, and the apparatus has a temperature range that can be changed. Since there is a limit due to the above restrictions and the like, in order to obtain a large-sized DNBB single crystal, there are many difficult problems such as a large amount of organic solvent solution being required at the time of starting the apparatus. Therefore, even if a DNBB single crystal can be obtained with great care, there is a drawback that the size can be increased only up to a certain range.

As a method for improving the above points, a solution in which a solute is dissolved is divided into two, a tank called a growth tank and a tank called a dissolution tank, and the solution temperature of each tank is maintained at different temperatures, so that the solute There is known a so-called Walker method for producing crystals, in which the solution is circulated between tanks after having a difference in solubility. For detailed literature on this, see, for example, J. Novotny A Crystallizer for the Inve.
stigation of Conditions of Growth of Single Crysta
ls from Solutions, Kristall und Technik6,3, (1971) p
343-352 can be mentioned.

In the production of DNBB single crystal using the temperature change method, the temperature control of the solvent solution is particularly important. Because
This is because the change in the solution temperature results in a change in the solubility of the DNBB solute in the solution and thus affects the supersaturation degree of the solution, which is important for crystal growth. Changes in the degree of supersaturation during crystal growth affect the precipitation rate or dissolution rate of crystals. In the conventional temperature change method, desired temperature control is performed by minimizing the influence of the amount of heat that fluctuates due to the method of temperature control and the increase in the amount of solution. However, even if this method is used, it is very difficult to strictly control the temperature of the solution, and therefore, miscellaneous crystals may occur during crystal production, or many defects may occur inside the crystal. Many.

Even when the solution temperature can be managed with sufficient accuracy, the structure of the apparatus becomes complicated, for example, the heat contact with the outside is cut off and a precise temperature control circuit is attached to the manufacturing apparatus. .

That is, the DN has been used so far by the temperature change method.
Although BB single crystals have been produced, it has not been possible to easily and reliably obtain large single crystals.

[0014]

Regarding the temperature change method used as a method for producing a DNBB single crystal, Japanese Patent Application No. Hei.
Although there is a method described in No. 186093, it is a method that requires precise solution temperature control. This is because, based on the principle of the temperature change method itself, the precipitation amount and rate of the DNBB solute in the solution are controlled by controlling the solution temperature. However, even if the temperature can be controlled within a certain range,
It is difficult to eliminate the possibility that defects will occur in the manufactured crystal due to environmental fluctuations that inevitably occur. In addition, there is a problem that the crystal manufacturing apparatus itself becomes complicated and expensive in order to perform this temperature control.

That is, the problem to be solved by the present invention is to avoid the problem inherent in the temperature change method that the temperature fluctuation of the solution inside the apparatus affects the crystals to be produced, and use an effective apparatus to It is to provide a method for surely producing a good-quality DNBB single crystal.

[0016]

As a result of earnest research, the inventors of the present invention have conducted a DNBB crystal growth while periodically changing the temperature of a DNBB solution with a constant temperature range.
The present invention has been completed by finding that the above problems can be solved by depositing B.

That is, the present invention comprises a solution of an organic solvent,
A method for producing a single crystal of DNBB represented by the following formula [1], comprising:

Embedded image The organic solvent solution is placed in an environment in which solution deterioration components are removed, and DNBB is periodically changed within a constant temperature range in the growth tank in which DNBB is deposited to grow a single crystal. The present invention provides a method for producing a DNBB single crystal, which carries out the precipitation of.

The present invention will be described in detail below.

The DNBB single crystal produced by the method of the present invention refers to a single crystal of a compound having the structure represented by the above formula [1]. It is known that some DNBB single crystals have different crystal structures depending on the manufacturing temperature, the organic solvent used, and the like. Among these, a single crystal having the following space group and lattice constant, space group Cc (# 9) lattice constant a = 1.02 nm b = 2.35 nm c = 0.69 nm β = 123 ° (hereinafter referred to as α-type single crystal) It is known that the second-order nonlinear optical performance when used as a second-order nonlinear optical material is high. Therefore, for use as a second-order nonlinear optical material, α-type DNBB single crystal is preferable. Further, the lattice constant of the organic crystal changes slightly depending on the growth conditions, the quality of the crystal, and the difference in the measurement temperature. Therefore,
The α-type DNBB single crystal referred to here also includes those having a lattice constant slightly different (± 3% or less) from the lattice constant described.

The organic solvent used in the method of the present invention is an organic solvent capable of dissolving DNBB, and the solubility of DNBB is changed by changing the temperature of the solution containing DNBB as a solute. Anything will do. Even if it is a solid at room temperature, it is included in the organic solvent in the present invention as long as it is a liquid at the use temperature. Further, as long as these conditions are satisfied, a single organic solvent or a mixed solvent composed of a plurality of organic solvents may be used.

There are several organic solvents which satisfy these conditions, but it is preferable that the solvent has a wide temperature range in which a DNBB single crystal can be precipitated and has a high boiling point. As a result of diligent efforts, the present inventors have found that, for example, a ketone solvent exhibits favorable properties. Specific examples are acetone, acetonylacetone, benzylacetone, 2-dodecanone, 2-hexanone, 2-
Examples include pentanone. In particular, it is possible to dissolve DNBB in a high concentration relatively in a ketone solvent.
2,4-Pentanedione (acetylacetone) can be preferably used.

It takes a long time to grow a single crystal, but it is considered that the deterioration of the solution at this time affects the quality of the grown single crystal. The present inventors have found that blocking the DNBB solution from the outside air can prevent such solution deterioration.

There are several methods for shutting off from the outside air. For example, a method of introducing an inert gas to shut off the DNBB solution from the outside air can be considered. What is an inert gas? D
Any organic solvent solution containing NBB may be used as long as it does not change. For example, a rare gas such as argon or dry nitrogen can be used. Preferably, argon, which has a heavier specific gravity than air, can conveniently and effectively shut off the outside air,
It is valid. At this time, either a method of sealing the growth container after replacement with an inert gas or a method of providing a partial open portion to continuously flow out gas may be used. If the growth container can be hermetically closed, it is preferable to use the sealing method because the gas consumption can be reduced. As the inert gas, it is preferable to use one that has been purified using a commercially available gas purification column or the like. It is possible to maintain a constant gas purity,
This is because even if the crystal growth period is long, the solution deterioration can be prevented. When a gas purification column cannot be used, it is also possible to use a commercially available high-purity gas having a purity of 99.999% or more.

As another method for shutting off from the outside air, it is conceivable to reduce the pressure in the container containing the DNBB solution by using a vacuum pump or the like. in this way,
Since the solution itself is also placed under reduced pressure, it is necessary to consider changes in the solubility of DNBB, evaporation of the solvent, and the like. Although the contact between the deterioration-causing substance and the DNBB solution can be reduced by placing it under reduced pressure, the degree of the reduction is closely related to the degree of vacuum. Desirably, after the pressure is reduced, the above-mentioned inert gas is used. Replacing the gas component in the container is more effective and desirable.

Although the reason why the solution deterioration can be prevented by blocking the solution from the outside air has not been specified, the atmosphere is
It is presumed that the organic solvent solution containing is containing a substance or gas that causes a phenomenon such as a color change due to deterioration. Such deterioration-causing substances include CO ₂ ,
NO _x or O ₂ can be considered.

Further, the solute precipitation referred to here means that the solubility of the solute is changed by the change of the solution temperature and the excess amount of the solute is recrystallized. As the solute to be precipitated, DNBB is used as at least one of the components.
Anything is acceptable, including.

In the method of the present invention, during the crystal growth of DNBB in the growth tank, DNBB is deposited while periodically changing the temperature of the DNBB solution within a constant temperature range. Here, the temperature range of the solution in the growth tank is the given DNB.
The solution B may be in any range as long as it goes through a saturated state and an unsaturated state, but from the required crystal size and quality, the following formula: 0.01% by weight <| S (T ₁ ) -S (T ₂ ) | <5.0
Wt% S (T): The solubility of DNBB at solution temperature T (unit: wt%) T _1: Growth tank minimum temperature of the solution at T _2: the maximum temperature of the solution of the growth tank T ₂ -T ₁ : By setting the range as represented by the solution temperature range in the growth tank, the DNBB can be efficiently used.
A single crystal can be obtained. Under the above conditions, the DNBB solute to be precipitated is sufficiently supplied to the surface of the DNBB seed crystal, and it is easy to obtain a large single crystal.
More preferably, the following formula, 0.10 _{wt% <| S (T 1)} -S (T 2) | <0.7
5% by weight S (T): solubility of DNBB at solution temperature T (unit:% by weight) T ₁ : minimum temperature of solution in growth tank T ₂ : maximum temperature of solution in growth tank T ₂ -T ₁ : If the range is represented by the temperature range of the solution in the growth tank, it is possible to prevent abnormal miscellaneous crystals and disappearance of dissolution of seed crystals, and it becomes easy to obtain desired crystals. The term "solubility" as used herein means the solubility shown by the solubility curve B on the precipitation side (see Fig. 1) measured by the method described in Example 1 below.

Further, the fluctuation cycle of the solution temperature in the growth tank is not necessarily constant, and it does not matter as long as it does not completely dissolve the seed crystal.
By allowing crystal growth to occur within a fluctuation period of longer than 72 minutes and less than 72 hours, it becomes easy to obtain a good-quality single crystal while improving the efficiency of crystal growth. More preferably, if it is longer than 1 hour and shorter than 4 hours, the crystal surface can be dissolved and regenerated in a short time, which is more efficient.

As a method of changing the temperature, for example,
An example is a method in which an organic solvent solution container is placed in a constant temperature oil tank and the oil temperature is controlled to gradually change the solution temperature. In this case, as for the accuracy of controlling the temperature of the constant temperature bath, a high accuracy is required in the conventional temperature change method. However, in the present invention, the accuracy of the temperature of the organic solvent solution is within ± 0.5 ° C. If it can be controlled by, the temperature change can be effectively utilized and a good DNBB single crystal can be obtained.

Any method can be used as the crystal production method as long as it uses a temperature change method, but preferably,
The organic solvent solution is divided into a growth tank and a dissolution tank for dissolving DNBB, and the organic solvent solution is circulated between the dissolution tank and the growth tank, so that the solute D is continuously formed.
A so-called Walker method for depositing NBB is preferable. Because this method originally has the advantage that continuous crystal growth can be performed,
This is because the temperature controllability had extremely severe conditions, and there was a problem in that it was difficult to manufacture the device. By applying the present invention to the Walker method, crystals can be produced more effectively.

When the Walker method is used, regarding the temperature of the solution to be set, etc., the respective temperatures are a <T ₃ <b and c <T ₄ <d and T ₃ , T ₄ <e (T ₃ : dissolution tank Temperature of the organic solvent solution in: T ₄ : temperature of the organic solvent solution in the growth tank a: minimum temperature of the solution required to dissolve a predetermined amount of DNBB in the dissolution tank b: within the limit of stable dissolution of DNBB in the dissolution tank Maximum temperature of a certain solution c: The minimum temperature of the solution at which the deposition rate is the maximum for the deposition of DNBB in the growth tank as a single crystal d: The maximum temperature of the solution at which DNBB can be deposited in the growth tank) e: boiling point of organic solvent) is preferable. Within this range, the solution can be stably prepared without boiling the solvent.

The temperature of the solution in the growth tank is DNBB.
If the solubility of is 0.1% by weight or more, crystal growth can be preferably performed. More preferably, it may be 0.5% by weight or more. This is because if the solubility of the solution in the growth tank is high, the amount of solute that can be taken out can be increased by changing the temperature difference between the solution and the growth tank, and the crystal production can be carried out quickly. The "solubility" here
Means the solubility shown by the solubility curve A on the dissolution side (see FIG. 1) measured by the method described in Example 1 below.

On the other hand, the relationship between the temperature T ₃ of the organic solvent solution in the dissolution tank and the temperature T ₄ of the organic solvent solution in the growth tank is S (T ₃ ) −S (T ₄ ) <5.0 Weight% (S (T): solubility of DNBB when the solution temperature is T (weight%)) is preferable because a DNBB single crystal can be stably precipitated. This is because if there is an extremely large difference in solubility, the stability of the solution in the growth tank may change, and the formation of miscellaneous crystals may be induced. More preferably, S (T ₃ ) -S (T ₄ ) <1.0 wt% (S (T): DNBB solubility (wt%) when the solution temperature is T) is more stable. Crystal growth can be performed. The “solubility” referred to herein means the solubility shown by the solubility curve A on the dissolution side (see FIG. 1) measured by the method described in Example 1 below.

Further, by setting the circulation speed of the organic solvent solution between the growth tank and the dissolution tank at less than 50 ml / min, crystal growth can be stabilized. To be precise, the amount of DNBB solute supplied to the growth tank is determined by the difference in DNBB solubility between the growth tank and the dissolution tank and the circulation amount of the solution. This is because the supply is possible. More preferably, the circulation rate is 10 ml /
When the amount is less than the minute, there is a remarkable effect on the reduction of crystal defects and the like, and the crystal growth can be performed with due consideration of the crystal quality.

The present inventor, in the production of a DNBB single crystal,
From the principle of crystal growth using the temperature change method, extremely accurate solution temperature control is required, and even if the temperature accuracy is high, crystal defects may occur. I had to consider that it existed. Especially, DNB with strong growth anisotropy
In the B single crystal, it was a very important problem to eliminate the possibility. Therefore, focusing on the surface state during crystal growth, it was found that miscellaneous crystals can be reduced by depositing and dissolving DNBB solute on the crystal surface for an appropriate period of time and temperature. This method does not require much high temperature accuracy from the temperature control of the growth tank to the temperature control of the melting tank. It was also experimentally found that it was good.

Utilizing these characteristics, a crystal manufacturing apparatus,
Particularly, with respect to the apparatus to which the Walker method is applied, it has become possible to manufacture a DNBB single crystal having a satisfactory crystal quality with a relatively simple structure.

[0037]

EXAMPLES The present invention will now be specifically described with reference to examples, but the scope of the present invention is not limited to these.

Example 1 (1) Measurement of Solubility Change (Solubility Curve) with Temperature Change 2,4-Pentanedione was used as a crystallization solvent, and the solubility of DNBB in 2,4-pentanedione was first measured. did. When measuring solubility,
(New Experimental Chemistry Course 1 Basic Operation II, The Chemical Society of Japan, Maruzen
p223 to p250) was used as a reference. The measurement was performed in the following order. A certain amount of 2,4-pentanedione (500 ml 20
(° C) is placed in an Erlenmeyer flask and heated on a hot plate to the solution temperature to be measured. Next, the DNBB powder weighed with a precision balance (JP-160 manufactured by YMC Co., Ltd.) is gradually charged into an Erlenmeyer flask prepared. The solution is heated to a predetermined temperature, and the temperature is maintained while stirring with a magnetic stirrer to dissolve. After a certain time (about 2 hours), visually check D
Determine if NBB has dissolved. Here, if it is dissolved, it returns to again. Through these operations, the solubility curve A on the dissolution side was derived.

On the other hand, according to the solubility curve A, DNBB /
A saturated solution of 2,4-pentanedione is prepared, placed in a constant temperature oil bath and gradually cooled. The solution was visually observed, and the temperature at which the DNBB solute began to precipitate was measured to obtain a solubility curve B on the precipitation side.

Solubility curves A and B are the boundaries that define the stability of solute precipitation from solution, respectively. For example, Advanced Crystal Growth, PMDryburgh e
t al.edit. 1987 Prentice Hall International (UK) Lt
On pages 208 to 211 of the d., a detailed explanation of the meaning of these solubility curves is given. That is, the solubility curve A is a state in which the solute is stably dissolved in the solution and the solute does not precipitate (hereinafter referred to as a stable region).
And, although it is still stable as a solution, it is a region where precipitation of solute starts (hereinafter referred to as metastable region) by some action from the outside (eg, seed crystals consisting of solute components are added to the solution). ) And the boundary. On the other hand, the solubility curve B shows a boundary between the metastable region and a state in which solute precipitation starts (hereinafter, referred to as an unstable region) without any action from the outside. In order to obtain a good single crystal, it can be seen that the DNBB single crystal grows from the seed crystal when the solute is precipitated in the metastable region and ideally along the solubility curve A.

As a result of the measurement, as shown in FIG. 1, both of the solubility curves A and B have a change in solubility with respect to a temperature change, and in the measurement temperature region, the solubility increases as the temperature rises. It turns out to have a coefficient. It was confirmed that a DNBB single crystal can be produced by utilizing this change in solubility.

(2) Preparation of DNBB Seed Single Crystal Based on the DNBB solubility curve obtained by the method shown in Example 1, an attempt was made to produce a DNBB single crystal by the Walker method.
First, seed crystals were prepared by the following method. First, DNB
B powder was dissolved in acetone at a concentration of about 0.1% by weight. Then, put the solution in an Erlenmeyer flask, about 24 ℃
In a temperature-controlled environment, acetone was gradually evaporated to recrystallize DNBB. Of the recrystallized DNBB, a flat single crystal (size: approximately 2 mm × 1 mm × 0.1 mmt) was used as a seed crystal. The production of this seed crystal is based on the production method of an α-type DNBB single crystal described in JP-A-1-45388.

(3) Preparation of DNBB Single Crystal Next, a solution was prepared using the crystal manufacturing apparatus shown in FIG. First, 500 g of 2,4-pentanedione was placed in each of the growth tank container 5 and the dissolution tank container 12, and the atmosphere in each tank was changed to argon. next,
The constant temperature baths 1 and 11 for controlling the solution temperature were used and kept until the solvent temperature reached 70 ° C. The constant temperature bath used can control the temperature inside the bath to within a set temperature ± 0.5 ° C. Silicon oils 2 and 13 are filled in the constant temperature baths 1 and 11, respectively, and a solution temperature stabilizer 8 is mounted in the precision constant temperature bath 1 that houses the growth bath 5. The inside of the growth tank 5 can be agitated by a magnetic stirrer 3 and a stirrer tip 4.

Next, 25 g of DNBB powder 14 was put into the dissolution tank 12. After that, the circulation of the solution between the growth tank 5 and the dissolution tank 12 was started using the two circulation pumps 9 and 10. The circulation rate was 5 ml / min. In addition, DNBB /
The flow of the 2,4-pentanedione solution 6 is indicated by an arrow in FIG. The solution was held in the growth tank 5 for about 12 hours while being slowly stirred by a magnetic stirrer. Thus, the solution in the manufacturing apparatus was a saturated solution at 70 ° C. Next, in the growth tank 5 that became the saturated solution,
The DNBB seed crystal 7 prepared in advance was gently attached. Then, while slowly rotating the seed crystal 7 (rotation speed: 5 rotations / minute), the solution temperature in the dissolution tank 12 was set to 0.
The temperature was raised to 72 ° C at 2 ° C / hour. At this point, the DNBB solution fed into the growth tank 5 becomes a supersaturated solution due to the difference in solution temperature between the two tanks, which precipitates a solute around the seed crystals and crystal growth occurs.

When the solution temperature in the growth tank was stable at 70 ° C. and the solution temperature in the dissolution tank was 72 ° C., the solution temperature in the growth tank was changed by the constant temperature tank at the temperature cycle shown in FIG. Growth tank reference temperature of 70 ℃ ± 1 ℃, fluctuation cycle 4
Time.

When the crystals were taken out after being kept as they were for 30 days, it was confirmed that transparent and single-domain single crystals were generated from the seed crystals. It was found that, except for the growth region from the seed crystal, no miscellaneous crystals were generated at all, and good crystal growth was performed.
When this crystal was observed with a polarizing microscope in a crossed Nicol state, it was confirmed that the crystal was a single crystal because the entire crystal was uniformly quenched.

Further, when a part of this crystal was crushed and analyzed by an X-ray diffraction method, the result as shown in FIG. 4 was obtained. This result was in agreement with the chart of α-type DNBB described in JP-A-1-45388. This allows DN
It was confirmed that the BBα type single crystal grew stably.

Example 2 An experiment was carried out in the case where the solvent used for crystal production was acetone. First, the solubility curve of DNBB was derived by the same method as in Example 1. The solubility of DNBB in acetone was not so large as compared with the case of 2,4-pentanedione, but the solubility increased when the solution temperature was increased. It was confirmed that it has a positive solubility coefficient.

Next, seed crystals were produced in the same manner as in Example 1.

Next, using the crystal production apparatus shown in FIG. 2 similar to Example 1 (3), the temperature of the saturated solution in the growth tank and the dissolution tank before the start of crystal growth was set to 22 ° C., and the solution temperature in the dissolution tank was changed. Was heated to 24 ° C. at 0.2 ° C./hour and then held at 22 ° C. ± 1 ° C. with a fluctuation period of 2 hours, and a DNBB single crystal was prepared in exactly the same manner as in Example 1 (3). It was made. As a result, it was confirmed that a transparent and single-domain single crystal was generated from the seed crystal. However,
Compared with Example 1, the size was rather small because the difference in solubility was small. It was found that, except for the growth region from the seed crystal, no miscellaneous crystals were generated at all, and good crystal growth was performed. When this crystal was observed with a polarizing microscope in a crossed Nicol state, it was confirmed that the crystal was a single crystal because the entire crystal was uniformly quenched.

Further, when a part of this crystal was crushed and analyzed by an X-ray diffraction method, it was in agreement with the chart of α-type DNBB. From this, it was confirmed that the DNBBα-type single crystal was stably grown even if different solvents were used.

Comparative Example 1 In the same operation as in Example 1, the experiment was continued for 30 days without changing the temperature of the growth tank. After the experiment was completed, the crystals were observed, and from the observation under a crossed Nicols of a polarization microscope,
The extinction was confirmed, but when the surface was examined in detail, a terraced part could be seen. When the crystal was measured by X-ray topography, the terraced parts were the overlapping parts of the thin DNBB single crystal, and were not a single region single crystal, but a laminated body of thin film single crystals. I found out that

Although the temperature of the growth tank was kept unchanged, a slight temperature change which fluctuates depending on the environment affects the crystal growth and induces defects in the crystal growth process, resulting in the above results. . From this, it was confirmed that the DNBB single crystal manufacturing method by intentionally utilizing the temperature change of the growth tank is an effective method.

[0054]

According to the present invention, a single crystal of DNBB can be easily and reproducibly manufactured, and a large DNB can be manufactured.
It becomes easy to obtain a B single crystal.

[Brief description of drawings]

1 shows a solubility curve of DNBB in 2,4-pentanedione obtained in Example 1. FIG.

FIG. 2 shows an overview of a Walker method crystal production apparatus used in Example 1.

FIG. 3 is a temperature change diagram of the growth tank used in Example 1.

4 is a powder X of DNBB single crystal obtained in Example 1. FIG.
A line diffraction pattern is shown.

[Explanation of symbols]

 1 Precision Temperature Chamber 2 Silicon Oil 3 Magnetic Stirrer 4 Stirrer Chip 5 Growth Tank Container 6 DNBB / 2,4-Pentanedione Solution 7 DNBB Seed Crystal 8 Solution Temperature Stabilizer 9 Circulation Pump 10 Circulation Pump 11 Constant Temperature Tank 12 Dissolution Tank Container 13 Silicone oil 14 DNBB powder

Claims (18)

[Claims] 1. A method for producing a single crystal of DNBB represented by the following formula [1] from an organic solvent solution, which comprises: The organic solvent solution is placed in an environment in which solution deterioration components are removed, and DNBB is periodically changed within a constant temperature range in the growth tank in which DNBB is deposited to grow a single crystal. A method for producing a DNBB single crystal, which comprises depositing 2. The method according to claim 1, wherein the environment in which the solution deterioration component is removed is created by blocking the organic solvent solution from the outside air with an inert gas. 3. A DNBB single crystal having the following space group and lattice constant, space group: C _c (# 9) lattice constant: a = 1.02 nm b = 2.35 nm c = 0.69 nm β = 123 ° The method according to claim 1, wherein the single crystal having the same is produced. 4. The method according to claim 1, wherein the solvent of the organic solvent solution is a ketone solvent. 5. The method according to claim 4, wherein the ketone solvent is 2,4-pentanedione. 6. The temperature range of the solution in the growth tank has the following formula: 0.01% by weight <| S (T ₁ ) −S (T ₂ ) | <5.0.
Wt% S (T): The solubility of DNBB at solution temperature T (unit: wt%) T _1: Growth tank minimum temperature of the solution at T _2: the maximum temperature of the solution of the growth tank T ₂ -T ₁ The method according to any one of claims 1 to 5, which is represented by a temperature range of the solution in the growth tank. 7. The temperature range of the solution in the growth tank has the following formula: 0.1% by weight <| S (T ₁ ) −S (T ₂ ) | <5.0% by weight S (T): solution temperature Solubility of DNBB at T (unit: wt%) T ₁ : minimum temperature of solution in growth tank T ₂ : maximum temperature of solution in growth tank T ₂ −T ₁ : solution temperature range in growth tank A method according to any one of claims 1 to 5 as represented. 8. The fluctuation cycle of the solution temperature in the growth tank is
8. The method according to claim 1, wherein the time is longer than one minute and less than 72 hours.
The method according to any one of claims 1 to 4. 9. The fluctuation cycle of the solution temperature in the growth tank is
9. The method of claim 8, which is more than 1 hour and less than 4 hours. 10. The temperature of the organic solvent solution is set to a set temperature ±
The method according to any one of claims 1 to 9, wherein the dissolution bath is housed in a thermostatic bath that can be controlled with an accuracy within 0.5 ° C. 11. The organic solvent solution is divided into a dissolution tank in which DNBB is dissolved and a growth tank in which DNBB is precipitated to grow a single crystal, and the organic solvent solution is circulated between the dissolution tank and the growth tank. , DN that is a continuous solute
The method according to any one of claims 1 to 10, wherein the precipitation of BB is performed. 12. When circulating the organic solvent solution, a temperature T _{1 of the} organic solvent solution in the dissolution tank,
The temperature T ₂ of the organic solvent solution in the growth tank is a <T ₁ <b and c <T ₂ <d and T ₁ , T ₂ <e (T ₁ : the temperature T of the organic solvent solution in the dissolution tank T ₂ : Temperature of the organic solvent solution in the growth tank a: Minimum temperature of the solution required to dissolve a predetermined amount of DNBB in the dissolution tank b: Maximum temperature of the solution that is the limit of stable dissolution of DNBB in the dissolution tank c: The minimum temperature of the solution at which the deposition rate is the maximum limit for the precipitation of single crystals in the growth tank d: The maximum temperature of the solution at which DNBB can be precipitated in the growth tank) e: The boiling point of the organic solvent) The method according to any one of claims 1 to 11, which satisfies the following. 13. The temperature of the organic solvent solution in the growth tank is set such that the solubility of DNBB in the organic solvent solution in the growth tank is 0.1% by weight or more. The method according to item 1. 14. The method according to claim 13, wherein the temperature of the organic solvent solution in the growth tank is set so that the solubility of DNBB in the organic solvent solution in the growth tank is 0.5% by weight or more. 15. The relationship between the temperature T ₃ of the organic solvent solution in the dissolution tank and the temperature T ₄ of the organic solvent solution in the growth tank is S (T ₃ ) −S (T ₄ ) <5.0% by weight (S (T): solubility (% by weight) of DNBB when the solution temperature is T)) The method according to any one of claims 1 to 14. 16. The relationship between the temperature T ₃ of the organic solvent solution in the dissolution tank and the temperature T ₄ of the organic solvent solution in the growth tank is S (T ₃ ) −S (T ₄ ) <1.0 wt% (S (T): the solubility (wt%) of DNBB when the solution temperature is T)). 17. The circulation speed of the organic solvent solution between the growth tank and the dissolution tank is less than 50 ml / min.
17. The method according to any one of items 1 to 16. 18. The circulation speed of the organic solvent solution between the growth tank and the dissolution tank is less than 10 ml / min.
7. The method according to 7.