JPS61285285A - Photochromic material and photochromic coating film - Google Patents

Abstract

PURPOSE:To provide the titled material composed of a novel thioindigo compound containing long-chain alkyl group, storable for a long period without causing discoloration after the color change induced by photo-irradiation, useful as an information recording medium and capable of forming a high-quality accumulated monomolecular films. CONSTITUTION:The compound of formula [R is -CnH2n+1 (n is integer of >=10); X is none or a bond such as -OCO-, -COO-, etc.; A is derivative of benzene ring, naphthalene ring, etc.] is used as the objective material. The compound of formula can be synthesized e.g. by reacting n-octadecylbenzene with sulfuric acid, converting the resultant p-octadecylbenzenesulfonic acid through its chloride, p-octadecylthiophenol and p-octadecylphenylthioglycol to 5- octadecylthioindoxyl and reacting the product with a potassium ferricyanide.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to novel photochromic materials belonging to the thioindigo family.

BACKGROUND ART A photochromic substance is a substance that has the property (photochromism) of reversibly changing its chemical structure accompanied by a change in color upon irradiation with light. Recently, attempts have been made to use the color change of photochromic substances for information storage.

Problems to be Solved by the Invention However, even if conventional photochromic substances change color, they change and return to their original structure during short-term storage, so they have not been put to practical use for information storage purposes. It wasn't.

An object of the present invention is to provide a photochromic material that does not change during long-term storage even after undergoing changes, and is a good material for information storage media.

Means for Solving the Problems The photochromic material of the present invention is represented by the following general formula.

YoiHere, R is an alkyl group represented by 10n'2n-1-t ("≧1o, n: an integer), and X is absent or -
A bond represented by 000-, -Coo-, -NHCO-, -CONH- or id-〇- represents a derivative such as a benzene ring or a naphthalene ring.

The novel thioindigo compound represented by the above formula exhibits good photochromism with significantly less discoloration after color change, and further exhibits photochromic properties with even less discoloration by forming I and B films.

Thioindigo species generally undergo a cis-trans photoisomerization reaction, which is expressed as trans and cis forms, using two types of light, hzo and hzo', having different energies. Once exposed to light, conventional thioindigo molecules switch from the trans form to the cis form, but automatically switch back to the trans form through a thermal reaction even without exposure to light. A feature of the present invention is that stabilization of the cis form is achieved by introducing a long-chain alkyl group into R and suppressing the photoisomerization reaction by steric hindrance.

Further, the long-chain alkyl group of R is also an important element when constructing the LB film. The pigment skeleton serves as a hydrophilic group and the long-chain alkyl group serves as a hydrophobic group, forming a good monomolecular film on the air-water interface.

The inventors investigated the length of H and found that R has 1 carbon number.
It has been found that a substance having a particle size of 0 or more (preferably 14 to 25) can constitute a good LB film, and that the stability of the substance itself and the stability achieved by forming the LB film can be achieved.

Examples Example 1 Hereinafter, as a first example, a typical method for synthesizing the compound described above will be shown.

(a) 1 mole of n-octadecylbenzene and 16 sulfuric acid
After heating ゜y at 126-130'C for 3 hours.

After cooling to 60-70'C, it was slowly poured into crushed ice, resulting in a jelly-like precipitate. After adding sodium chloride to form the sodium salt, the mixture was extracted several times with ether in a separatory funnel to extract sodium p-octadecylbenzenesulfonate.

(b) 1 mol of sodium p-octadecylbenzenesulfonate obtained in step a was suspended in dry DMF, and 1.6 mol of thionyl chloride was added dropwise thereto, followed by stirring at room temperature for about 1 hour.

Pour the reaction mixture into ice water containing dissolved sodium chloride,
The generated precipitate was filtered and washed with water to obtain p-octadecylbenzenesulfonyl chloride.

(C) 7 mol of sulfuric acid and 300 y of crushed ice were placed in a flask and cooled to -6°C, and while stirring, 1 mol of p-octadecylbenzenesulfonyl chloride obtained in step b was gradually added. Thereafter, 4.9 mol of zinc powder was gradually added using O-SoC while being careful not to raise the temperature.

After stirring at 6°C for 1 hour, the water bath was removed, the temperature was raised to 106°C in an oil bath, and heating and stirring was continued for 6 hours. The reduced product was extracted with ether, washed with water, and dried under reduced pressure to obtain p-octadecylthiophenol.

(d) 3 moles of p-octadecylthiophenol
Dissolve in 3% NILOH aqueous solution 1oOoCC, add 1 mol of monochloroacetic acid neutralized with Na2CO3,
The mixture was heated and stirred at 0°C for 1 hour.

After the reaction, p-octadecylphenylthioglycolic acid was obtained by acidifying with hydrochloric acid. White crystals were obtained by recrystallization from benzene.

(e) PCB51.3 in 1 mol of p-octadecylphenylthioglycolic acid and 1000 cO of chlorobenzene
mol and heated at 70'C for 2 hours, after cooling, klcl,
After adding 1.1 mol and further heating at 60'C for 1 hour, hydrolysis was performed and benzene was added.

The organic layer was collected and washed with water, and then purified using a silica gel column to obtain 6-octadecylthioindoxyl.

(f) Thioidoxyl was obtained by reacting phenylthiol in the same manner as in d and e. This was reacted with p-nitrone dimethylaniline and thionaphthenequinone-2-(
4'-dimethylamino)anil was synthesized.

(g) 5-octadecylthioindoxyl and thionaphthenequinone-2-(4
'-Dimethylamino)anyl 0.6 mol each and 4 g of piperidine were added to 100 C of chlorobenzene.
Heat and stir at 6 to 118°C for 2 hours to obtain 5-
Octadecylthioindigo was obtained.

The novel thioindigo of the present invention had a significantly lower thermal isomerization reaction rate in the dark than the typical thioindigo shown in the figure below, which does not have a long-chain alkyl substituent.

Example 2 In Example 1, f is p instead of phenylthiol.
-5- shown in the figure below using -t-butylphenylthiol
Octadecyl, s'-t-butylthioindigo was obtained.

Similar to Example 1, the thermal isomerization reaction rate in the dark was significantly lower than that of thioindigo which does not have a long-chain alkyl group.

Example 3 By following the route a to e in Example 1, 6-octadecylthioindoxyl was obtained.

1 mole of 6-octadecylthioindoxyl dissolved in alcohol is added to an aqueous NaOH solution, potassium ferricyanide is added, the mixture is stirred at room temperature for one hour, and then acidified with hydrochloric acid to produce 5,5'-dioctadecylthioindigo as shown in the figure below. was gotten.

Similar to Example 1, the thermal isomerization reaction rate in the dark was significantly lower than that of thioindigo which does not have a long-chain alkyl group.

Example 4 1×10 ml of a 0.1×10 m01/l chloroform solution of the thioindigo of Example 1 was dropped onto a clean water surface having an area of aOO1. The chloroform solution expanded to form a monolayer of thioindigo at the air-water interface. While measuring the surface pressure (π) of the thioindigo monolayer, the monolayer was compressed by sweeping the water surface with a water-repellent bar. The relationship between the occupied area per molecule (mu/molecule) and the surface pressure (dyne/ax) in this operation is shown in the figure. The figure suggests that the thioindigo of the present invention forms a good monolayer.

The surface pressure of the thioindigo monolayer is 1s dyne/α
A quartz glass plate whose surface had been hydrophobized with cadmium arachinate was vertically moved up and down while maintaining the same temperature. When immersed in water and pulled up, the thioindigo monomolecular film moved from the air-water interface to the surface of the quartz glass plate. By repeating this operation eight times, a monomolecular cumulative film of 32 layers on the front and back surfaces was formed on the quartz plate. When this monomolecular cumulative film was used to examine changes due to thermal reactions in the dark, the changes were extremely small as in Example 1.

We also attempted to form a monomolecular film in a similar manner using thioindigo, which does not have a long-chain alkyl group, but no monomolecular film was formed at all.

Effects of the Invention According to the present invention, a photochromic dye that undergoes significantly less change due to thermal reaction in the dark was obtained.

[Brief explanation of drawings]

The figure is a graph showing the relationship between the surface pressure of thioindigo and the molecular occupied area in an example of the thioindigo material of the present invention.

Claims (2)

[Claims] (1) A photochromic material consisting of a compound represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Here, R is -C_nH_2_n_+_1 (n≧10, n
: integer), X is absent or -OCO-, -COO-, -NHCO-, -CON
The bond represented by H or -O-, A represents a derivative such as a benzene ring or a naphthalene ring. (2) A photochromic coating consisting of a monomolecular cumulative film of a photochromic material consisting of a compound represented by the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Here, R is -C_nH_2_n_+_1 (n≧10, n
: integer), X is absent or -OCO-, -COO-, -NHCO-, -CON
A bond represented by H- or -O- represents a derivative such as a benzene ring or a naphthalene ring.