JPH10251251A - Molecular magnetic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new diarylethene compound having a hetero 5-membered cycle substituted with a stable radical group on its aryl site, and useful as such a molecular magnetic material as to develop its molecular magnetic property or make the property disappear by photochromic reaction. SOLUTION: This new material is a diarylethene compound shown by formula I (R<1> and R<1> ' is each methyl; at least one of R<2> , R<2> ', R<3> , and R<3> ' is a stable radical group such as phenoxy, nitroxy or ferrocene, the others being each H or methyl) and exemplified by a compound expressed by formula II, which is obtained, for example, as follow: preparing a compound of formula III by reacting 2,4-dimethylthiophene and tetramethyl etylenediamine with n-BuLi and zinc chloride; adding dried tetrahydrofuran to a compound of formula IV and Pd(PPh3 )4 held in another vessel for mixing thereof; reacting the resultant mixture with a compound of formula III, mercury oxide, iodine, N-BuLi, C5 F10 in sequential way in this order; and dissolving the resultant compound in dioxane and subsequently adding hydrochloric acid thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material capable of generating and extinguishing molecular magnetism by a photochromic reaction.

[0002]

2. Description of the Related Art A conventional photochromic material reversibly generates two isomers having different electronic states by the action of light, and the photoabsorption spectrum accompanying the photoisomerization, photoreversibility such as refractive index or dielectric constant. Changes in physical properties have been applied to optical functional materials such as optical memory media or optical switching elements. For these purposes, the development of photochromic molecules that are durable and heat irreversible has been promoted. At present, diarylethene molecules having sufficient repetition durability and thermal irreversibility have been obtained (M. Irie, Pure Appl. Chem. 6).
8 (1996) 1367).

[0003]

However, reversibly changing molecular physical properties, however, are mostly related to molecular transitions, and none related to magnetism. If the generation / extinction of molecular magnetism can be optically controlled, its application range is wide. The possibility of controlling many electronic elements based on the magnetic control, not limited to the optical memory, is opened.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photochromic reaction for generating and annihilating molecular magnetism (paramagnetism). With respect to the molecular material having the above, such an object can be solved by a diarylethene having a 5-membered hetero ring substituted by a stable radical group in the aryl moiety. Diarylethene, which has excellent durability and thermal stability, has two aryl groups in the ring-opened form that are not connected by a conjugated chain, but in the case of a ring-opened form, conjugation spreads throughout the molecule and the two aryl groups are connected by a conjugated chain. You. When a stable radical is introduced into each of the two aryl groups, a difference appears in the spin correlation between the ring-opened form and the ring-closed form. In the following condition (1),
If the ring is closed, the paramagnetism will disappear. But,
In the case of (2), a triplet state appears.

[0005]

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(In the formula, .R represents a stable radical.)

[0007]

Next, the present invention will be described in detail. As the diarylethene, those having a thiophene ring, a furan ring, or a pyrrole ring are candidates. Diarylethene as a group is preferred. Examples of the stable radical include a phenoxy group, a nitroxy group (B), and ferrocene (C).

[0008]

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The nitroxy group (B) includes, for example, the following radical groups.

[0010]

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A diarylethene having an aryl group with a thiophene ring having these stable radicals as a substituent was synthesized, and the optical change of its molecular magnetism was measured. The paramagnetism disappeared due to the photocyclization of the diarylethene, and the photoopening reaction was initiated. Was reappeared.

[0012]

【Example】

 Example 1 Compound (4) was synthesized as follows.

[0013]

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(Wherein TMS represents a trimethylsilyl group.) 2.35 g of 2,4-dimethylthiophene (2) (20.
95 mmol, 1.2 eq), 2.35 g (20.24 mmol) of tetramethylethylenediamine (TMEDA)
l) was taken and dissolved in dry ether. To this, 14.7 ml (23.53 mmol) of n-BaLi was added dropwise at room temperature, and the mixture was stirred for 1 hour. 22.5 ml (22.49 mmol) of an ether solution of zinc chloride was added thereto, and dry THF was further added thereto, followed by stirring for 1.5 hours. In a separate container, 7.0 g (17.3 mmol) of compound (5) and Pd (PP
h ₃ ) ₄ 395 mg (0.342 mmol, 2 mol)
%), And after substitution with argon, dry THF was added and stirred. The compound (6) prepared above was gradually added dropwise thereto, and the mixture was stirred as it was overnight. Water was added to stop the reaction, extracted with chloroform, dried over MgSO ₄ and concentrated.
This was subjected to column separation with a hexane solvent to obtain white crystals (7). The yield of compound (7) is 2.065 g.
(30.7% yield). FIG. 1 shows the NMR spectrum of the compound (7).

[0015]

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Compound (7) in a 200 ml three-necked flask
Was taken in 2.052 g (5.3 mmol) and dissolved in benzene. 1.36 g of mercury oxide (6.3 mmo)
l) and 1.65 g (6.5 mmol) of iodine were added, and the mixture was stirred at room temperature for 3.5 hours. Mercury oxide was removed by suction filtration, the filtrate was washed with hypo-water, and the benzene layer was dried over MgSO ₄ . After concentrating the benzene layer, the column was separated with a hexane solvent. The yield of compound (8) was 1.
674 g (yield 61.32%). Compound (8)
Is shown in FIG.

[0017]

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Compound (8) 1.0 g (1.94 mmol)
l) in THF and n-BuLi 2.
2 ml (3.49 mmol) were added dropwise. After 35 minutes, perfluorocyclopentene was added. At this time, the mixture was added in three portions, and the total amount was 0.16 ml (1.19 mmol). The yield of compound (9) was 0.233 g (yield 1
2.7%).

[0019]

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0.1 g of compound (9) in 5 ml of dioxane
(0.105 mmol) and 0.4 ml of hydrochloric acid
(4.6 mmol) was added and left at room temperature for 63 hours.
Compound (4) is applied to a silica gel column (developing solution: hexane)
To obtain 0.073 g (yield 86.1%).

Example 2 Compound (4) was dissolved in 10 ml of benzene (1 × 10 ^−5).
mol / l), 3 mg of PbO _{2 was} added thereto, and the change in absorption spectrum was measured. The results are shown in FIG. Generation of a ring-opened radical was observed. In FIG. 3, the solid line is the absorption spectrum of the ring-opened product, and the dotted line is the spectrum of the ring-opened radical.

On the other hand, the compound (4) was dissolved in 10 ml of benzene (1 × 10 ⁻⁵ mol / l), a closed form was formed by irradiation with ultraviolet light, and then contacted with PbO ₂ to measure the change in spectrum. FIG. 4 shows the results. Formation of a closed ring radical was observed. In addition, the solid line in FIG. 4 shows the spectrum of the closed body, and the dotted line shows the spectrum of the radical of the closed body. FIG. 5 shows the ESR spectra of the ring-opening radical and the ring-closing radical. An ESR spectrum was observed for the ring-opened radical, but no ESR spectrum was observed for the ring-closed radical. This is considered to be due to the fact that in the closed ring, the spin becomes a singlet state and paramagnetism is lost.

Example 3 The ring-opened radical of Example 2 was irradiated with 366 nm light to measure the change in radical concentration accompanying ring closure. FIG. 6 shows the results. A decrease in the radical concentration (annihilation of paramagnetism) was observed with the photocyclization.

[0024]

According to the present invention, there can be obtained a material in which paramagnetism is generated and extinguished by a fetochromic reaction.

[Brief description of the drawings]

FIG. 1 is a ¹ H-NMR spectrum of an intermediate compound (7) of an example.

FIG. 2 is a ¹ H-NMR spectrum of an intermediate compound (8) of an example.

FIG. 3 is a spectrum diagram of a ring-opened product and a ring-opened radical of an example.

FIG. 4 is a spectrum diagram of a closed body and a closed radical of an example.

FIG. 5 is an ESR spectrum diagram of a ring-opening radical and a ring-closing radical of an example.

FIG. 6 is a diagram showing a change in an ESR spectrum by ultraviolet irradiation in the example.

Claims (4)

[Claims] 1. A diarylethene having a 5-membered hetero ring substituted by a stable radical group in an aryl moiety. 2. The diarylethene according to claim 1, which has pyrrole, thiophene, furan or selenophene as the 5-membered heterocyclic ring. 3. The method according to claim 1, wherein the stable radical has a phenoxy group, a nitroxy group or a derivative thereof.
The diarylethene according to the above. 4. A molecular magnetic material comprising diarylethene having the following molecular structure. Embedded image (Where R ¹ and R ¹ ′ are methyl groups, R ² and R ² ′ are methyl groups, hydrogen atoms or stable radical groups, R ³ ,
R ³ ′ represents a hydrogen atom, a methyl group or a stable radical group, and at least one of R ² , R ² ′, R ³ and R ³ ′ represents a stable radical group. )