JPH0631190B2 - Method of making organic thin film crystal - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an organic thin film crystal.

(Prior Art) As a method for producing an organic crystal, there are used three types of crystal growth from a vapor phase, crystal growth from a solution, and crystal growth from a molten state.

(For these three types of crystal growth methods, see Maruzen, New Experimental Chemistry Course, Volume 1, Basic Operation II, PP.639-750,
It is well summarized in. (Problems to be Solved by the Invention) However, preparation of organic thin film crystals has hardly been studied so far, and the report is limited to crystals of polymer compounds. (For example, Izumi's comprehensive report (Journal of the Crystal Growth Society of Japan, Vol. 11, PP. 117-134, 1984)
(Year) describes examples of polyethylene thin film crystals and polyacetylene thin film crystals. The present situation is that there is no suitable method for producing an organic thin film single crystal that is not a polymer compound.

An object of the present invention is to provide a method for producing an organic thin film single crystal on a polymer film.

(Means for Solving the Problems) According to the present invention, in a method for producing an organic thin film crystal in which an organic crystal dispersed in a polymer film is used as a seed crystal and an organic substance is crystallized into a thin film on the film, A method for producing an organic thin film crystal is obtained, which is characterized in that a temperature gradient is applied in a certain direction in a plane of a polymer film and crystal growth is performed in such a direction.

The polymer film material used in the present invention may be any material as long as it has a thin film forming ability. Examples include polystyrene and polyvinyl chloride. The compound used as the seed crystal used in the present invention may be any compound as long as it can be dispersed as crystals in the polymer film and can cause crystal growth of the target compound. The temperature gradient in the in-plane direction of the polymer film containing the seed crystal of the present invention may be provided by any method, but the gradient must be obtained only in a certain direction in the plane. As an example, a method of contacting only one side of the substrate with a heat source,
There is a method of placing the substrate in a liquid or gas having a temperature gradient. The magnitude of the temperature gradient and its absolute temperature are determined by the combination of the seed crystal and the compound used to grow the crystal, but if the temperature gradient is too small, the seed crystal may be polycrystallized because it exists in the entire film. Must be set. When a temperature gradient is given in a certain direction within the plane of such a polymer film, a gradient may be generated in a direction perpendicular to the plane.

(Operation) When a single crystal is grown from a seed crystal, the seed crystal is generally 1
Must be individual. If there are multiple seed crystals, growth does not start from each and does not become a single crystal.

However, in the present invention, the growth occurs only from the seed crystal that has reached the growth start temperature earliest because of the temperature gradient despite the presence of a plurality of seed crystals. Once growth begins, crystallization progresses according to the temperature gradient,
Moreover, a single crystal is obtained because the grown crystal grows faster (homoepitaxial growth) than the seed crystal grows (heteroepitaxial growth).

(Example) FIG. 1 is a schematic view showing an example of the present invention. 18 mm x
Polystyrene (0.50 g) having a molecular weight of 600,000 and 2-hydroxy-4-methoxybenzylidene-4′-bromoaniline (hereinafter abbreviated as MS ₄ BrA) are placed on an 18 mm glass plate 2 (thickness: about 0.15 mm). 5000 solution of 1,4-dioxane (13.0 g) in which (0.20 g) was dissolved
Spin-coated at rpm. MS at 80 ℃ for 1 hour
_{4 The} polystyrene film 3 in which BrA microcrystals are dispersed in the film is
Obtained on the glass plate 2.

Melting point block 1 was used as a heat source in the following crystal growth experiments. A spacer 7 made of plastic so that only one side of the glass plate coated with the film 3 directly contacts the melting point block
Inclining and standing still with 2.0 mg of 2-hydroxy-
4-Methoxybenzylidene-4'-butylaniline 4
(Hereinafter, abbreviated as MS ₄ BuA), and the melting point block 1
Was heated to 50 ° C. to be in a liquid crystal state. While maintaining the temperature at 50 ° C., the glass plate 5 with nothing coated thereon was placed thereon and cooled to 32 ° C. at a rate of about 0.5 ° C. per minute.
After standing at 32 ° C. for about 10 minutes, a thin film single crystal 4 of MS ₄ BuA was obtained between the film 3 and the glass plate 5 placed thereon. According to the microscopic observation, crystal growth starts from the side opposite to the side in contact with the melting point block 1 and progresses toward the side in contact with the melting point block 1 to give a plurality of elongated single crystals. Recognize.

The crystal-liquid crystal transition temperature of the organic thin film crystal grown on the film 3 is 36.5 ° C., and this thin film turns red by irradiation with 365 nm ultraviolet light. In addition to the method of contacting one side of the glass plate 2, a single crystal could be formed by performing a similar experiment by contacting one corner of the glass plate 2.

Furthermore, on the film 3, 2-hydroxy-4-methoxybenzylidene-4'-heptylaniline, 2-hydroxy-
Thin film crystals of salicylideneanilines such as 4-methoxybenzylidene-4'-octylaniline could be prepared by the same method. The glass plate 5 placed on the crystal growth was not always necessary, and thin film crystals could be formed without the glass plate 5. However, in order to obtain a uniform film thickness,
It is not limited to a glass plate, but it is desirable that it has some cover.

As a reference example, when the above-mentioned thin film crystal was formed by adhering a glass plate coated with a polymer film to a melting point block, crystal growth occurred from a plurality of points, and the whole did not become a thin film single crystal. . Therefore, it is clear that the temperature gradient of the present invention is effective for single crystallizing the whole.

(Effect of the Invention) According to the present invention, a method for producing an organic thin film single crystal on a polymer film was obtained. In this example, the seed crystal dispersed in the polymer film is different from the compound that grows into a thin film crystal, but the same compound may be used. Further, the polymer film material is not limited to polystyrene, and its coating method may be not only spin coating but also a casting method, an interface film forming method, or the like. Furthermore, it does not necessarily have to be fixed on the glass plate.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, 1 is a heat source whose temperature can be controlled, 2 is a glass plate, 3 is a polymer film in which seed crystals are dispersed, 4 is a layer to be crystallized (for example, liquid crystal), 5 is a glass plate covering, and 6 is the entire cover ,
Reference numerals 7 denote plastic spacers, respectively.

Claims (1)

[Claims] 1. A method for producing an organic thin film crystal in which an organic crystal dispersed in a polymer film is used as a seed crystal to crystallize an organic substance on the film in a thin film shape, wherein a temperature gradient is applied in a certain direction within a plane of the polymer film. And a method for producing an organic thin film crystal, which comprises growing a crystal in such a direction.