JP2006024527A - Lb film that can give electrical conductivity and electrical conductive lb film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film comprising an organic material that becomes semipermanent electro conductive by irradiating light, and a multi layer electro conductive film comprising a thin film of an organic material. <P>SOLUTION: The electro conductive film is a Langmure-Blodgett film (LB film) having a double layer structure comprising a thin film having an electron acceptor organic compound and a thin film comprising an organic compound having in its one molecule a photosensitive functional group and a group that irreversibly chemically changes when electron is given. The Langmure-Blodgett film is given electrical conductivity by irradiating light to the film. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a Langmuir-Blodgett film (hereinafter referred to as LB film) capable of imparting conductivity by light irradiation. Further, the present invention relates to an LB film that is formed by irradiating the LB film with visible light or ultraviolet light to form a conductor.

  Conductive organic substances are extremely limited and are compounds having a specific structure that can stably accept electrons. Some of these become conductive when pressure is applied, and others become conductive when irradiated with light.

  The present invention is a photosensitive conductive film, and particularly comprises a thin film in which an LB film made of an electron acceptor organic compound and an LB film made of an electron donor are laminated.

  The conductive film having a double structure has a conductivity equal to or higher than that of a metal made of a polar film and a nonpolar dielectric film or a hetero film in which two polar films having different polarization directions are stacked. An insulating film that can be used for electrical insulation with a conductive film has been proposed (Patent Document 1).

  In this film, at least one of the dielectric films is an LB film. However, the conductive thin film is not made conductive by being excited by light or the like.

  In addition, a tetracyanoquinodimethane (hereinafter referred to as TCNQ) having high electrophilicity and a photosensitive electron donor substance are pulverized and mixed, dissolved in an organic solvent, and used to form an LB film. A method for obtaining a sensitive thin film has also been proposed (Non-Patent Document 1). This film is once given conductivity by light irradiation, but soon the conductivity is lost. The reason is considered that a salt is formed with the cation derived from the electron donor in which the TCNQ receiving the electron coexists and becomes an insulator.

  As described above, there is no organic thin film in which conductivity is imparted by conventional light irradiation and the conductivity is maintained semipermanently.

JP-A-6-132517 Chemistry Letters (The Chemical Society of Japan) 1999 pages 241-242

  The present invention provides an organic thin film capable of providing conductivity semipermanently by irradiating light, and also provides an organic thin film having conductivity. That is, as a result of investigating the mechanism by which the LB film containing TCNQ loses electrical conductivity, TCNQ is not a molecule composed of a clear hydrophilic part and a hydrophobic part, so that the arrangement of the same molecule in the LB film is disturbed. And found that it is easily combined with a cation generated from an electron donor to form a salt, and that the electron donor itself is not excited by light and emits a relatively small proportion of electrons, The present invention has been completed.

  The present invention relates to a thin layer of an electron acceptor organic compound, and a thin layer of an electron donor composed of an organic compound having a photosensitizing group and a group irreversibly chemically changed by donating electrons in one molecule. It is an LB film which can be provided with conductivity and has a double layer structure.

  The present invention also provides a thin layer of an electron donor comprising an organic compound having in its molecule a thin layer comprising an electron acceptor organic compound, a photosensitizing group, and a group irreversibly chemically changed by donating electrons. The conductive LB film having a double layer structure in which the electron acceptor portion is used as a conductor by irradiating the LB film having a two layer structure with visible light or ultraviolet light.

  The thin film obtained by the present invention can be selectively made conductive particularly by irradiating the thin film with visible light to ultraviolet light (hereinafter collectively referred to simply as light). Therefore, it can be used effectively in the field of optoelectronics such as the creation of optical memories and IC circuits.

  The present invention relates to an organic compound (hereinafter also simply referred to as an electron acceptor) that accepts electrons, for example, TCNQ and its quinone ring substituted with a hydrophobic group, protoporphyrin, acetylene oligomer, thiophene, pyrrole, thiazyl LB film made of azulene, indene, indole, paraphenylene, naphthylene, anthracene, aniline, phthalocyanine, ferrocene, etc., or derivatives thereof, in particular, a compound having a methylene chain represented by the following general formula (1), particularly a methylene chain TCNQ with 7 to 16 alkyl groups bonded to the quinone ring has an excellent film forming performance with a well-ordered molecular arrangement when it is used as an LB film. Therefore, a preferred LB film is provided in the present invention.

（但し、ｎは１２〜２３の整数を表す）

(However, n represents an integer of 12 to 23)

  In addition, a compound having both a photosensitizing group and a group that irreversibly chemically changes by donating an electron in one molecule (hereinafter also simply referred to as a photosensitized electron donor) is a known photosensitization. There is no particular limitation as long as it has a functional group such that an intermolecular bond is cleaved by a group and light, one of which emits electrons and the other becomes a radical.

  Examples of each of these functional groups include those that are cleaved by light and emit electrons, such as ethylenediamines bonded to groups and aryl groups represented by formulas (3) to (4), respectively. The functional groups shown in 4) are recommended.

In particular, amines in which a long-chain alkyl group is bonded to an amino group have a good LB film-forming property, and therefore diamines in which an alkyl group having 10 to 24 carbon atoms is bonded are recommended. Among them, those having an alkyl group having 12 carbon atoms can give good results.

  The photosensitizing group is not particularly limited, and a conventionally known photosensitizing group can be used, but a rhenium complex represented by the formula (5) is particularly suitable.

  In the present invention, as described above, it is important to have a LB film layer of a compound having both a photosensitizing group and a group that is excited by light and cleaves a chemical bond and emits an electron. Thus, the reaction efficiency when irradiated with light is remarkably improved, and as a result, the conductivity in the LB film of the present invention is increased. In addition, in the present invention, since the electron acceptor and the photosensitized electron donor are each laminated as a monomolecular layer having a well-ordered molecular arrangement, the movement of electrons is performed very smoothly. In other words, the formation of a salt between the two does not cause decontamination.

  A preferred combination of the electron acceptor layer and the photosensitive electron donor in the present invention is a thin layer comprising an electron acceptor represented by the following formula (6) and a photosensitive electron donor represented by the formula (7). This is an LB film having a two-layer structure made of a thin layer.

Next, the method for forming the LB film of the present invention is not particularly limited, and a generally used LB film manufacturing method is applied as it is. For example, on a clean water surface, a solution in which a solute that forms a film in a solvent insoluble in water is developed. After the solvent is removed by evaporation, a glass or quartz plate to be a substrate is inserted, and a single substrate is placed on the substrate. In this method, an LB film is formed as a molecular layer. By repeating this, it is possible to form an LB film having a multilayer structure.

  That is, in the present invention, the electron acceptor is spread on the water surface, an LB film is formed on the substrate, and then the photosensitive electron donor solution is similarly spread on the water surface to form the LB film. A new monomolecular film is formed on the processed substrate. By repeating the above-described film formation as necessary, a plurality of two-layer structures of a thin layer (monomolecular layer) made of an electron acceptor and a thin layer (monomolecular layer) made of a photosensitized electron donor are repeatedly provided. A thin film can be obtained.

  Of course, the order of forming the LB film is not limited to the above, and it is naturally possible to form the photosensitive electron donor layer first and then form the electron acceptor layer thereon.

  Thus, the obtained LB film capable of imparting electrical conductivity is excited by irradiating light having the wavelength most suitable for excitation of the photosensitizing group constituting the film, and promotes electron movement, whereby an electron acceptor is obtained. The layer becomes a conductor layer. At the same time, the photosensitive electron donor layer becomes an insulating layer, and a conductive LB film having a multilayer structure is obtained.

  Moreover, the light irradiated in order to provide electroconductivity will not be specifically limited if it can excite a photosensitive electron donor. The type of light used depends on the type of photosensitive group, but the relationship between the wavelength of light suitable for excitation and the structure of the functional group is already well known. Moreover, even if it is a functional group whose relationship is not sufficiently known, those skilled in the art can easily find it by a simple experiment. Usually, light having a wavelength in the near-ultraviolet to ultraviolet region, specifically, about 30 to 3000 nm is used.

(1) Synthesis of electron donor site (a) Synthesis of erythro-2- (N-didodecylamino) -1,2-diphenylethanol (2)
Trans-stilbene oxide 492.7 mg (2.5 mmol), di-n-dodecylamine 6.9527 g (19.6 mmol) and p-toluenesulfonic acid monohydrate 39.4 mg (0.2 mmol) were distilled into 20 mL of benzene under an argon atmosphere. In addition, the mixture was refluxed for 11 days. Extracted with aqueous NaOH (1M) and ethyl acetate. Next, the organic layer was washed with saturated brine, dried over anhydrous Na ₂ SO ₄ , and then the solvent was removed. The resulting crude product was first subjected to column chromatography on silica gel using hexane: ethyl acetate = 20: 1 as the effluent solvent, followed by silica gel column chromatography using hexane: chloroform = 1: 2 as the effluent solvent. Purified by chromatography. 425.2 mg of a pale yellow oil crude product was obtained. ¹ H NMR (400 MHz, CDCl ₃ ): δ0.86 (m, 6H, 2 × CH ₃ ), 1.01 (b, 40H, 2 × alkylchain
(CH ₂ ) ₁₀ ), 2.41 (m, 2H, didodecylamine
α-CH ₂ ), 2.55 (m, 2H, didodecyla-mine α-CH), 3.76 (d, J = 5.5Hz, 1H, benzylic), 5.20 (d, J = 5.5Hz, 1H, benzylic), 7.0− 7.2 (m,
10H, phenyls).

(B) erythro-1- {N- [4-pyridyl] methyl} amino} -2- (N-didodecylamino) -1,2-
Synthesis of diphenylethane (3)
erythro-2- (N-didodecylamino) -1,2-diphenylethanol
315.4 mg (0.6 mmol) and 0.24 mL (1.7 mmol) of triethylamine were added to 10 mL of dichloromethane under an argon atmosphere. The mixture was stirred for 70 minutes while passing argon. The reaction solution was cooled to −29 ° C., 0.051 mL (0.6 mmol) of methanesulfonyl chloride was added to 1 mL of dichloromethane, and the well-mixed solution was slowly added dropwise to the reaction solution under an argon atmosphere. Stirring was continued while maintaining the temperature of the reaction solution at −10 ° C. or lower. After 5 days, 0.08 mL (1.0 mmol) of methanesulfonyl chloride was added to 0.5 mL of dichloromethane, and the mixture was added slowly to the reaction solution under an argon atmosphere. Further, 0.24 mL (1.7 mmol) of triethylamine was added to 0.5 mL of dichloromethane, and the mixture was added to the reaction solution under an argon atmosphere. After 18 hours, the reaction solution was a pale yellow solution, and a white solid had precipitated on the vessel wall. To 0.5 mL of dichloromethane, 0.06 mL (0.6 mmol) of 4-aminomethylpyridine was added, and the well-mixed solution was added to the reaction solution under an argon atmosphere. The reaction solution was returned to room temperature and stirred for 2 hours. 4-Aminomethylpyridine was added to the reaction solution, and after completion of the reaction, the reaction solution was poured into dichloromethane and washed with distilled water. The organic layer was washed with saturated brine, dried over anhydrous Na ₂ SO ₄ , and the solvent was removed. The resulting crude product was purified by silica gel column chromatography using hexane: ethyl acetate = 10: 1, 2: 1 as an effluent solvent. After chromatography, 212.8 mg of a reddish orange oil (yield 60%) was obtained.

¹ H NMR (400 MHz, CDCl ₃ ): δ0.87-1.32 (b, 46H, 2 × aikylchain (CH ₂ ) ₁₀ CH ₃ ),
2.08 (m, 2H, didodecylamineα-CH ₂ ), 2.35 (m, 2H, didodecylamineα-CH ₂ ), 3.40
(d, J = 14.6Hz.1H, diastereotopic CH ₂ ), 3.57 (d, J = 14.6Hz, 1H, disastereotopicCH ₂ ),
3.80 (d, J = 8.4Hz, 1H, benzylic), 4.11 (d, J = 8.4Hz, 1H, benzylic), 7.0−7.3 (m, 12H, β-
pyridyl and
phenyls), 8.46 (dd, 2H, α-pyridyl).

(2) Synthesis of photosensitized sites (a) (bpy) Re (CO) ₃ cl (4)
(* Bpy represents 2,2'-bipyricline)

Re (CO) ₅ Cl 493.8 mg (1.4 mmol) and 2,2′-bipyridine 215.9 mg (1.38 mmol) were added to distilled toluene 160 mL under an argon atmosphere and refluxed. The progress of the reaction was confirmed by TLC (hexane: ethyl acetate = 10: 1). After 75 minutes, the reflux was stopped, left to cool. After cooling, the solid deposited in the reaction vessel was collected by filtration through a glass filter. 524.7 mg (yield 83.2%) of yellow powdery crystals were obtained. ¹ HNMR (400 MHz, CD ₃ CN): δ 7.52 (t, 1H), 8.06 (t, 1H), 8.19 (d, 1H) 9.08 (d, 1H) (all
bipyridyl).

(B) Synthesis of (bpy) Re (CO) ₃ (CF ₃ SO ₃ ) (5)
(bpy) Re (CO) ₃ Cl
263.0 mg (0.6 mmol) was added to 18.4 mL dichloromethane under an argon atmosphere. The reaction solution was stirred for 15 minutes while passing argon through it. CF ₃ SO ₃ H under argon atmosphere in the reaction solution
0.347 mL (3.9 mmol) was added. After stirring for 60 minutes, diethyl ether was slowly added little by little and allowed to stand. The precipitated crystals were collected by filtration with a glass filter. 218.0 mg (66.5% yield) of yellow needle crystals were obtained. ¹ H NMR (400 MHz, CD ₃ CN): δ 7.72 (t, 1 H), 8.30 (t, 1 H), 8.49 (d, 1 H), 9.04
(d, 1H) (all bipyridyl).

(3) Synthesis of photosensitized electron donor (compound of formula (7)) Compound 3 107.0 mg (0.2 mmol), Compound 5 65.3 mg (0.1 mmol), NH ₄ PF ₆ 181.9 mg (1.1 mmol) were distilled. Added to 5 mL of THF under an argon atmosphere. After 24 hours, stirring was stopped and the solvent was removed. The crude product was purified by column chromatography on alumina using hexane: ethyl acetate = 10: 1, 1: 2 as an effluent solvent. After chromatography, 68.9 mg (51% yield) of a yellow clay solid was obtained. ¹ H NMR (400 MHz, CD ₃ CN): δ0.77-1.28 (b, 46H, 2 × alkylchain (CH ₂ ) ₁₀ CH ₃ ) 2.08 (
m, 2H, didodecylamine
α-CH ₂ ), 2.35 (m, 2H, didodecylamineα-CH ₂ ), 3.29 (s, 2H,
methylene), 3.72 (d, 1H, benzylic) 3.91 (d, 1H, benzylic), 4.11 (d, 1H, benzylic), 6.9-7.3 (m, 12H, phenyls
and pyridyls), 7.7 (t, 2H, bipyridyl), 7.85 (d, 2H, pyrydyl), 8.14
(t, 2H), 8.25 (d, 2H), 9.08 (d, 2H) (all
bipyridyl).

(4) Electron acceptor compound
As octadecyl-tetracyano qunodimethane (1) (also referred to as C18TCNQ), NKX-735 manufactured by Hayashibara Biochemical Laboratory Co., Ltd. was used as it was.

(5) Preparation of LB film (a) π-A curve measurement About 1 L of milli-Q water was put in the water tank of the apparatus, and the water temperature was set to about 20 ° C. using a temperature controller. After washing the water surface, a substrate prepared as a 0.02 mM chloroform solution was developed on the water surface using a microsyringe. Next, the barrier was closed, and the π-A curve was measured to obtain target pressure.

(B) LB film preparation A glass substrate was set in the apparatus, and the solution was developed in the same manner as in the π-A curve measurement. Using the target pressure obtained from the π-A curve, an LB film was prepared by pulling up the substrate. Next, a new LB film is formed in the same manner using the substrate having the LB film. Thus, an LB film having a two-layer structure composed of each molecular layer of the compound (1) and the compound (5) was produced.

(5) Light irradiation The Xe lamp was applied to the glass substrate on which the LB film was laminated. At this time, a filter (HOYA COLOR OPTICAL GLASS U-340) that cuts light other than around 340 nm was attached to the Xe lamp in order to irradiate only light in the vicinity where there was Re absorption of Compound 1.

(6) Conductivity measurement The film obtained in (b) and the film not irradiated with light were placed on a comb-shaped electrode (manufactured by BAS) with a gap of 5 μm, and the conductivity was measured. No current flowed through the film before irradiation, but current flowed at a voltage of about 2 volts or more in the film after light irradiation. The results are shown in FIG.

  In the present invention, since conductivity can be imparted only to the portion where the LB film is irradiated with light, it is applied to the field of optoelectronic devices such as circuit formation of various electronic parts, optical memory, and optical switches.

FIG. 1 is a graph showing the difference in conductivity between when the LB film comprising the compound (1) layer and the compound (5) layer laminated on the platinum comb electrode is irradiated with light and when it is not irradiated. .

Claims (4)

  A double layer structure of a thin layer made of an electron acceptor organic compound, a photosensitizing group, and a thin layer of an electron donor made of an organic compound having a group that irreversibly chemically changes by donating electrons in one molecule. Conductive LB film comprising   From a double layer of a thin layer made of an electron acceptor organic compound, a photosensitizing group, and a thin layer of an electron donor made of an organic compound having a group irreversibly chemically changed by donating electrons in one molecule. A conductive LB film having a double layer structure in which the electron acceptor portion is a conductor by irradiating visible light or ultraviolet light to the LB film. The LB film having a double layer structure according to claim 1 or 2, wherein the electron acceptor organic compound is represented by the following general formula (1):

(However, n represents an integer of 12 to 18) The electron donor which consists of an organic compound which has in a molecule | numerator the photosensitizing group and the group which changes irreversibly by donating an electron in one molecule is represented by following General formula (2). LB film with double layer structure

(However, X ⁻ represents PF ₆ ⁻ , BF ₄ ⁻ , ClO ₄ ⁻ )

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