JP2007314365A - Method for forming organic single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a large-size organic single crystal excellent in crystallinity and to provide the organic single crystal. <P>SOLUTION: Gel 3 is formed by charging a gelling agent 2 into a solution 1 in which organic matter constituting the organic single crystal 4A is dissolved. The organic matter is supersaturated by cooling the gel 3 and then the crystal nucleus 4 of the organic matter is generated in the gel 3. In a method that the organic single crystal 4A is formed by growing the crystal from the crystal nucleus 4 formed in the gel 3, the optimal property of the gel 3 for crystal growth is specified. It is favorable that complex viscosity by gel oscillation is adjusted to 0.2 Pa s or more and 600 Pa s or less at 25°C and at a frequency of 1 Hz. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

 The present invention relates to a method for forming an organic single crystal, and more particularly to a method for forming an organic single crystal having a nonlinear optical effect.

  4-Dimethylamino-N-methyl-4-stilbazolium tosylate (4-dimethylamino-N-methyl-4-stilbazolium tosylate: hereinafter referred to as DAST) single crystal exhibits large nonlinearity and is used for optical communication Applications to electronic parts such as infrared light wavelength conversion devices, electric field sensors, optical sampling, optical memories using photochromic phenomena, and measurement probes for ultrahigh-speed ICs are expected. As a typical method for forming such an organic single crystal, there are a natural nucleus growth method and a seed crystal growth method.

  Formation of the organic single crystal by the natural nucleus growth method is performed as follows. First, an organic substance constituting the organic single crystal is dissolved in methanol or the like, and then the solution temperature is lowered so that the organic substance becomes supersaturated. When the solution becomes supersaturated, the organic matter is precipitated from the solution. An organic single crystal is obtained by growing the precipitate as a nucleus.

  On the other hand, in the seed crystal growth method, the organic single crystal obtained by the natural nucleus growth method is used as a seed crystal, the seed crystal is put into a solution, and the seed crystal is further developed by lowering the temperature. This is a method for obtaining an organic single crystal. This method is a suitable method for obtaining a large DAST single crystal that can be used for the above application.

  Although the natural nucleus growth method can form a single crystal with high crystallinity, it is difficult to control the position of nucleation. For this reason, when the nucleation position approaches in the growth process, the crystals come into contact with each other in the subsequent crystal growth process to be polycrystallized, or when grown in contact with the bottom of the growth vessel, a large stress is generated inside the crystal. Has been added to cause crystal defects.

  On the other hand, the seed crystal growth method is obtained by the natural nucleus growth method and inherits the defects of the seed crystal as they are. For this reason, when the quality of the seed crystal is poor, the obtained DAST crystal is polycrystallized or many crystal defects are introduced inside, and it is extremely difficult to obtain a large DAST crystal with high crystallinity. It was.

In Patent Document 1, a groove is formed on the surface of an inclined plate made of 4-fluoroethylene resin, an organic crystal nucleus is deposited on the inclined surface, and the crystal nucleus sliding down the inclined surface is captured by the groove. A method of growing into a single crystal is disclosed.
In the method described in Patent Document 1, a lower end portion of a crystal obtained by growth is in contact with a groove portion provided on a surface of a member made of 4-fluoroethylene resin that provides a place for crystal growth. In some cases, crystal defects occurred at and around the contact area.

Here, in the method for growing an organic single crystal from a solution in which an organic substance constituting the organic single crystal is dissolved, the inventor forms a gel by introducing a gelling agent into the solution, A method for forming an organic single crystal for crystal growth (hereinafter referred to as a gel method) has been proposed (Non-Patent Document 1).
JP 2000-256100 A Suzuki Chisato, Toshiki Guo and Akira Sakurai, Growth of Organic Nonlinear Optical Crystal DAST in In-Gel Growth, Applied Physics, Japan Society for Applied Physics, published on March 10, 2005, Vol. 34, no. 3, 52nd Applied Physics Related Lecture Program p. 76

  The gel method can form a large organic single crystal that is uniform and excellent in crystallinity as a whole as compared with the natural nucleus growth method, seed crystal growth method, or the method of Patent Document 1. After that, the inventors conducted intensive research and found that, depending on the properties of the gel, the increase in the number of nuclei generated in the organic single crystal caused a reduction in crystal size and a decrease in crystallinity, thereby affecting crystal growth.

  The present invention solves the above-mentioned problems, and by controlling the number of nuclei generated in an organic single crystal by specifying the optimum gel properties for crystal growth in the method for forming an organic single crystal using the gel method. The present invention provides a method for forming an organic single crystal capable of increasing the crystal size and improving the crystallinity.

  The present invention solves the above-mentioned problem relating to the formation of an organic single crystal, and forms a gel by introducing a gelling agent into a solution in which an organic substance constituting the organic single crystal is dissolved. In the method for forming an organic single crystal for growth, the complex viscosity due to vibration of the gel is adjusted to 0.2 Pa · s to 600 Pa · s at a temperature of 25 ° C. and a frequency of 1 Hz.

  According to the present invention, in the method for forming an organic single crystal using the gel method, the complex viscosity due to vibration of the gel is adjusted to 0.2 Pa · s or more and 600 Pa · s or less at a temperature of 25 ° C. and a frequency of 1 Hz. It is uniform. Therefore, a large and high quality organic single crystal can be obtained. In addition, it is possible to form an organic single crystal constantly. Here, when the complex viscosity is a frequency of 1 Hz, if it is less than 0.2 Pa · s, it is difficult for the gel to dissolve and retain crystals, and conversely if it exceeds 600 Pa · s, uniform gelation is difficult. is there.

  It is preferable to use a gelling agent that is classified as an organogel because it is easy to uniformly adjust the gel. The reason is that an organic single crystal is soluble in water, and a gelling agent that can be used in an organic solvent is preferable. There are hydrogels and organogels as gelling agents. Since hydrogels are gelled using water, they are not suitable for use in the method for growing organic single crystals according to the present invention. On the other hand, the organogel can be used in an organic solvent such as methanol, and when the organic solvent is required for dissolving the organic single crystal raw material and the use of moisture is not preferred as in the present invention, the gelling agent is used. Suitable as

  When the gelling agent is hydroxypropylcellulose, it is more preferable because the gel can be rapidly and uniformly adjusted, and a situation in which crystals cannot be precipitated and retained in a state where gelation is insufficient will not occur.

  According to the method for forming an organic single crystal of the present invention, it is possible to identify the optimal gel properties for crystal growth in the method for forming an organic single crystal using the gel method. It becomes possible to increase the crystal size and improve the crystallinity by the suppression.

Hereinafter, embodiments of the method for forming an organic single crystal of the present invention will be described with reference to the drawings.
(First embodiment)
The method for forming an organic single crystal according to the present embodiment is a method for growing an organic single crystal from a solution in which an organic substance constituting the organic single crystal is dissolved. By forming a gelling agent into the solution, a gel is formed. Crystal growth is performed in the gel.
FIG. 1 is a view for explaining a growth process of an organic single crystal by the forming method of the present invention.
In FIG. 1, hydroxypropylcellulose is charged as the gelling agent 2 into the organic solution 1 constituting the organic single crystal. At this time, the complex viscosity due to the vibration of the gel is 25 ° C. and the frequency is 1 Hz. The amount of the gelling agent 2 is adjusted so as to be 0.2 Pa · s or more and 600 Pa · s or less (FIG. 1A), and the gel 3 is produced (FIG. 1B). Subsequently, when the gel 3 is cooled, the organic matter becomes supersaturated, and crystal nuclei 4 of the organic matter are generated in the gel 3. And crystal growth advances from the crystal nucleus 4 formed in such a gel 3, and the organic single crystal 4A is obtained (FIG.1 (c)).

  In the crystal growth method according to the present invention, since crystal growth proceeds while being fixed in a gel, adjacent crystals do not gather together and become polycrystallized unlike normal solution growth. In addition, since there is no contact with the growth vessel and there is no need to install an inclined plate made of 4-fluoroethylene resin as described in Patent Document 1, crystals do not contact these members, and crystal defects An organic single crystal 4A excellent in crystallinity with a small amount can be obtained. In addition, by performing crystal growth in the gel, convection of the solution is suppressed compared to crystal growth performed in a normal solution, and the growth proceeds at a diffusion-controlled rate, making it easy to control the crystal growth rate and improving the crystallinity. An excellent single crystal can be obtained.

In particular, when the method of the present embodiment is performed on the formation of a DAST single crystal and a single crystal of a derivative thereof as an organic single crystal, as shown in FIGS. 1B and 1C, In the gel 3, the generation of stress due to contact with different members can be suppressed with respect to all the crystal planes of the DAST single crystal and the single crystal of its derivative. For this reason, the rate at which crystal defects and the like are generated can be reduced, and a single crystal having excellent crystallinity can be obtained.
In this embodiment, a gelling agent is first introduced into a solution in which an organic substance constituting an organic single crystal is dissolved (FIG. 1 (a)).

Here, a solvent will not be specifically limited if an organic substance is dissolved.
In particular, in the case of forming a DAST single crystal, the presence of water deteriorates the quality of the single crystal. Therefore, it is preferable not to use an aqueous solution during gel preparation and crystal growth. For example, methanol, ethanol It is preferable to use an organic solvent that dissolves alcohols such as propanol and organic substances such as acetonitrile.

  As the gelling agent, it is preferable to use an organogel such as hydroxypropylcellulose, polyethyleneimine, or polyvinylpyrrolidone because the organic solvent is used in the formation of a DAST single crystal.

  Any kind of organic substance can be used as the organic substance. However, the method of the present embodiment is not limited to 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) or other counter ions. 4-Dimethylaminobenzaldehyde-4-nitrophenylhydrazone (DANPH) or (−)-4- (4′-dimethylaminophenyl) -2- (2- Hydroxypropylamino) cyclobutene-3,4-dione (DAD: ((−)-4- (4′-dimethylaminophenyl) -2- (2-hydroxypropylamino)) cyclobutene-3,4 It can be suitably used in the formation of a single crystal such as dione).

  Subsequently, the solution containing the organic substance and the gelling agent is heated to gel the solution (FIG. 1 (b)). This gelation is preferably performed completely from the viewpoint of suppressing convection of the solution during crystal growth. Further, when the temperature of the prepared gel 3 is lowered, the organic substance becomes supersaturated as described above, and crystal nuclei 4 are generated in the gel 3 and grow to become an organic single crystal 4A.

  Here, the temperature required for the gelation of the solution is not particularly limited as long as the solution can be gelled, but it is preferably set to 40 ° C. to 60 ° C. or less, for example. As for the temperature lowering process of the gel necessary for crystal growth, it is preferable to gradually lower the temperature to a temperature lower than the temperature required for gelation, for example, about room temperature, from the viewpoint of stable crystal growth.

Hereinafter, formation of a DAST single crystal will be described as a specific example of formation of a single crystal by the method of the present embodiment.
A predetermined amount of DAST raw material powder is dissolved in an organic solvent such as methanol kept at 40 ° C. to 60 ° C. or less in a constant temperature water bath to prepare a DAST solution 1 as shown in FIG. Next, hydroxypropylcellulose is added as a gelling agent 2 to the solution 1 to produce a gel 3 (FIGS. 1A and 1B). Furthermore, the complex viscosity due to vibration of the gel is adjusted to a temperature of 25 ° C. and a frequency by, for example, adjusting the amount of the gelling agent by completely gelling the solution by maintaining the temperature in a constant temperature bath at 40 ° C. to 60 ° C. or lower. After adjusting so that it may be 0.2 Pa · s or more and 600 Pa · s or less at 1 Hz, the solution temperature is lowered. Then, the DAST crystal nucleus 4 is precipitated in the gel from the supersaturated gel, and the DAST single crystal 4A grows in the gel as described above. Finally, the gel temperature is lowered to 25 to 35 ° C. at a temperature lowering rate of 0.1 to 1.5 ° C./day. The time for forming the single crystal is 24 to 1000 hours.

  According to the embodiment described above, for example, when a DAST single crystal or a single crystal thereof is formed, an organic material having excellent crystallinity with an X-ray rocking curve half-value width of (0 0 1) plane of 30 arcsec or less. A single crystal can be obtained.

  FIG. 2 is a diagram showing an X-ray diffraction rocking curve of the (0 0 1) plane of the DAST single crystal. The X-ray diffraction rocking curve of the DAST single crystal obtained by the method of this embodiment has the shape of curve 5, and the complex viscosity due to vibration of the gel is adjusted to a temperature of 25 by adjusting the amount of the gelling agent. It can be seen that it is smaller than the half-value width of the X-ray diffraction rocking curve 6 of the DAST single crystal obtained by using a gel adjusted to be 0.2 Pa · s or less at 0 ° C. and a frequency of 1 Hz. Therefore, it can be seen that the crystallinity of the DAST single crystal obtained by the method of the present embodiment is superior to that obtained by the conventional method. Thus, according to the present invention, an organic single crystal that is uniform and excellent in crystallinity can be formed as a whole.

  As described above, according to the present embodiment, since the organic single crystal can be grown in the gel, it contacts with different members such as the bottom of the growth container and the groove portion of the inclined plate as in Patent Document 1. Therefore, the phenomenon that a large stress is applied to the inside of the crystal to cause crystal defects is not observed. In addition, since there are few crystal nuclei to be generated and it is possible to suppress the crystals grown in adjacent locations from being polycrystallized, it is possible to obtain a large organic single crystal that is homogeneous throughout and has excellent crystallinity.

Hereinafter, the present invention will be described specifically by way of examples.
Example 1
In this example, a DAST single crystal was grown using a gel as shown in FIG. A DAST solution was prepared by putting 2.8 g of DAST powder in 80 ml of methanol maintained at 55 ° C. in a constant temperature water bath. Next, 1.6 g of hydroxypropylcellulose was added to this solution. After the solution is completely gelled by maintaining at 55 ° C. in a constant temperature water bath, the complex viscosity due to the vibration of the gel is adjusted to 10 Pa · s when the temperature is 25 ° C. and the frequency is 1 Hz. The temperature was lowered to 35 ° C. over 30 days. As a result, a DAST single crystal was obtained from the gel. When the size of this DAST single crystal was measured, the width was about 9 mm, the length was about 2.0 mm, and the thickness was about 0.7 mm. Next, when the X-ray rocking curve of the (0 0 1) plane of the obtained DAST single crystal was measured, the X-ray diffraction rocking curve had the shape of the curve 5 in FIG. It was as small as arcsec and excellent in crystallinity.

(Example 2)
A DAST solution was prepared under the same conditions as in Example 1. Next, 8.0 g of hydroxypropylcellulose was added to this solution. Then, after the solution is completely gelled by maintaining at 55 ° C. in a constant temperature water bath, the complex viscosity due to vibration of the gel is adjusted to 260 Pa · s when the temperature is 25 ° C. and the frequency is 1 Hz. The temperature was lowered to 35 ° C. over 30 days. As a result, a DAST single crystal was obtained from the gel. When the size of this DAST single crystal was measured, the width was about 11 mm, the length was about 2.5 mm, and the thickness was about 0.9 mm. The X-ray diffraction rocking curve of the (0 0 1) plane of the obtained DAST single crystal measured in the same manner as in Example 1 has the shape of curve 5 in FIG. It was as small as arcsec and excellent in crystallinity.

(Comparative Example 1)
A DAST solution was prepared under the same conditions as in Example 1. Next, 0.4 g of hydroxypropylcellulose was added to this solution. Then, the solution is completely gelled by maintaining at 55 ° C. in a constant temperature water bath, and the complex viscosity due to the vibration of the gel is adjusted to 0.1 Pa · s when the temperature is 25 ° C. and the frequency is 1 Hz. Then, the temperature was lowered to 35 ° C. over 30 days. As a result, a DAST single crystal was obtained from the gel. When the size of this DAST single crystal was measured, the width was about 4 mm, the length was about 1.5 mm, and the thickness was about 0.3 mm. The X-ray diffraction rocking curve of the (0 0 1) plane of the obtained DAST single crystal measured in the same manner as in Example 1 has the shape of curve 6 in FIG. arcsec.

(Comparative Example 2)
A DAST solution was prepared under the same conditions as in Example 1. Next, 24 g of hydroxypropylcellulose was added to this solution. And when the said solution was gelatinized by hold | maintaining at 55 degreeC in a constant temperature water tank, a part of gelatinizer did not melt | dissolve in a solution but the uniform gel was not able to be produced.

(Comparative Example 3)
A DAST solution was prepared under the same conditions as in Example 1. Next, 0.4 g of cellulose was added to this solution. And when the said solution was gelatinized by hold | maintaining at 55 degreeC in a thermostat, the gelling agent did not melt | dissolve in a solution but the uniform gel was not able to be produced.

As is apparent from the above results, the DAST single crystal having excellent crystallinity can be obtained according to the forming method of the present invention.
As described above, the present invention has been described in detail based on the embodiments of the present invention, specifically. However, the present invention is not limited to the above contents, and various modifications and changes can be made without departing from the scope of the present invention. It can be changed.

It is a figure for demonstrating the growth process of the organic single crystal by the formation method of this embodiment. It is a figure which shows the X-ray-diffraction rocking curve of (0 0 1) plane of a DAST single crystal.

Explanation of symbols

1 Solution 2 Gelling agent 3 Gel 4 Crystal nucleus 4A Organic single crystal

Claims (5)

In the method for forming an organic single crystal, a gel is formed by introducing a gelling agent into a solution in which an organic substance constituting the organic single crystal is dissolved, and crystal growth is performed in the gel.
A method for forming an organic single crystal, wherein the complex viscosity due to vibration of the gel is adjusted to 0.2 Pa · s to 600 Pa · s at a temperature of 25 ° C. and a frequency of 1 Hz.  The method for forming an organic single crystal according to claim 1, wherein the gelling agent is classified into an organogel. In the formation method of the organic single crystal of Claim 1 or 2,
The method for forming an organic single crystal, wherein the gelling agent is hydroxypropylcellulose. In the formation method of the organic single crystal of Claims 1 thru | or 3,
The method for forming an organic single crystal, wherein the organic substance is 4-dimethylamino-N-methyl-4-stilbazolium tosylate or a derivative obtained by replacing tosylate with another counter ion. In the formation method of the organic single crystal of Claims 1 thru | or 3,
The organic substance is 4-dimethylaminobenzaldehyde-4-nitrophenylhydrazone or (−)-4- (4′-dimethylaminophenyl) -2- (2-hydroxypropylamino) cyclobutene-3,4-dione. A method for forming an organic single crystal characterized by the following.

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