JP2001288239A - Poltymer formed from triindole derivative, and optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer which comprises structural units derived from a triindole derivative, stably exhibits amorphousness, and can be formed into a thin film and provide an optical element prepared by using the same. SOLUTION: This polymer comprises structural units derived from a triindole derivative represented by formula (1), wherein R1 is a 1-14C linear or branched alkyl; R2 is a 2-14C linear or branched alkylene; and n is 5-15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel polymer comprising a novel triindole derivative and an optical element having the polymer.

[0002]

2. Description of the Related Art Carbazole is a molecule that has long been attracting attention as a photoconductive material. In particular, polyvinyl carbazole, which is a polymer containing carbazole, is widely used as an organic material.

For example, a product obtained by adding a pyrylium salt to polyvinyl carbazole has been put to practical use as a drum photoreceptor of a copying machine. Further, it has been clarified that a material obtained by doping fullerene as an acceptor into this polyvinyl carbazole exhibits a photorefractive property exceeding that of an inorganic crystal. Carbazole is thus used as a photoconductive material, but at present the research on materials having even better properties is being actively conducted.

[0004]

Therefore, the present inventors have paid attention to triindole which has this carbazole in the skeleton and has a planar three-fold symmetric structure. Compounds having a triindole skeleton have hitherto been used in the field of biological systems, where R in the following structural formula is H, CH ₃ , or CH ₂ C
Only those which are H ₂ N (CH ₂ CH ₂ ) ₂ O have been synthesized. Moreover, there is no disclosure of polymers composed of these compounds, and no reports have been made from the viewpoints of materials and physical properties (eg, photoconductivity).

[0005] The present inventors estimated the donor properties of the compound having a triindole skeleton and methylcarbazole using a molecular orbital calculation and surface analysis apparatus (AC-1, RIKEN Kiki Co., Ltd.) using MOPAC.
FIG. 1 shows the results of the molecular orbital calculation. Here for simplicity,
R in the above structural formula was calculated as a methyl group.
The HOMO of the obtained methyl carbazole is -8.2 eV
Whereas the HOMO of trimethylindole is-
It was 7.9 eV, and improvement of the donor property was confirmed. Also, as a result of measuring the ionization potential using the surface analyzer AC-1, octadecylcarbazole (R = C
The ionization potential of ₁₈ H ₃₇ ) was 5.9 eV, whereas that of trimethylindole was 5.3 eV. From the above results, it is expected that the compound having a triindole skeleton is very useful as a donor material.

[0006] However, the above 3
Some compounds having a triindole skeleton have been synthesized as by-products, but their usefulness has not been confirmed in the field of actual biological systems. There is a problem that the film cannot be thinned due to lack of properties. Therefore, the present invention has been made in view of the above circumstances, and the present invention
An object of the present invention is to provide a polymer comprising a novel triindole derivative which can overcome the above problems and is very useful as a donor material.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that birds containing carbazole in the skeleton and having high donor properties and wide flatness advantageous for obtaining conductivity are obtained. Compound having an indole skeleton (hereinafter, referred to as
Called "triindole derivatives". ) Can stably exhibit amorphous properties and be made into a thin film. For example, a donor such as a photoconductive material, a nonlinear optical material, a photorefractive (PR) material, and an electroluminescent (EL) material can be used. They have found that they are very useful as materials and have completed the present invention.

[0008] The means for solving the above problems are as follows. That is, <1> a polymer comprising a triindole derivative represented by the following general formula (1).

[0009]

Embedded image <In the general formula (1), R ¹ represents a linear or branched alkyl group having 1 to 14 carbon atoms, and R ² represents 2 to 1 carbon atoms.
4 represents a linear or branched alkyl group, and n represents 5 to 15. <2> In the general formula (1), R ¹ has 1 to ¹ carbon atoms.
8 represents a linear or branched alkyl group, and R ² has 4 carbon atoms.
Represents a linear or branched alkyl group of 10 to 10, and n is 8 to 1
2. A polymer comprising the triindole derivative according to <1> above, wherein <3> An optical element including a polymer comprising the triindole derivative according to <1> or <2>.

Since the polymer comprising the triindole derivative of the present invention has a high molecular distribution, it can easily obtain an amorphous property, whereby the thin film property is improved, and it can be used as an optical material. For this reason, by incorporating a functional substituent into the molecule that crosslinks triindole, the functional substituent can be easily introduced into the molecule, making it possible to construct a device using the interaction between triindole and the crosslinkable molecule. For example, it can be suitably used as a photoconductive material, a nonlinear optical material, a photorefractive (PR) material, an electroluminescent (EL) material, and the like.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polymer comprising the triindole derivative of the present invention is represented by the following general formula (1).

[0012]

Embedded image

In the general formula (1), R ¹ represents a linear or branched alkyl group having 1 to 14 carbon atoms. R ¹ preferably represents a linear or branched alkyl group having 1 to 8 carbon atoms, more preferably a linear or branched alkyl group having 1 to 2 carbon atoms. R ¹ in the general formula (1) is a group having 1 carbon atom
If the number of alkyl groups is 5 or more, the resulting polymer will have a reduced density of functional sites, and thus will have a reduced function as an optical material.

In the general formula (1), R ² represents a linear or branched alkyl group having 2 to 14 carbon atoms, preferably a linear or branched alkyl group having 4 to 10 carbon atoms, more preferably Represents 6 to 8 alkyl groups. When R ² in the general formula (1) is an alkyl group having 15 or more carbon atoms, the resulting polymer has a reduced density of functional sites, and thus has a reduced function as an optical material, When the number of carbon atoms is 1, the amorphous property is lost.

In the general formula (1), n represents 5 to 15, and preferably 8 to 12. When n is less than 4, the amorphous property is reduced. In the general formula (1),
Constituent groups having a CN group are difficult to synthesize at the ortho position (o position) due to problems such as steric hindrance.
Position) or para position (p position) is preferred. Any of the constituent groups having a CN group may be in the meta position (m position), or may be in the para position (p position). It may be at the para position (p position).

Particularly preferred as the polymer comprising the triindole derivative of the present invention is a polymer represented by the following general formula (2). R ¹ and R ² are a general formula
Same as (1).

[0017]

Embedded image

Next, a preferred embodiment of the method for producing a polymer comprising a triindole derivative of the present invention will be described. First, as shown below, oxindole is alkylated as a first step (Scheme 1). In addition to oxindole and alkyl halide, tetrahydrofuran as a solvent, potassium carbonate as a base, 18-
Use crown-6-ether. These are refluxed for at least 24 hours under a nitrogen atmosphere. At this time, the mixing ratio of oxindole, alkyl halide, and potassium carbonate is preferably 1: 2: 2 in molar ratio. Also, 18-crown-
6-ether is added in catalytic amount. After refluxing, the reaction solution is filtered, the solvent is distilled off, and the residue is purified by column chromatography. As the second step (Scheme 2),
The obtained alkyl oxindole is cyclized. At this time, phosphorus oxychloride is used as a reaction solvent and a dehydrating agent.
Phosphorus oxychloride is preferably about 10 times equivalent to alkyl oxindole. The reaction temperature is 100 ° C and the reaction time is 1
About two hours are preferable. The reaction product is purified by column chromatography. As described above, the triindole derivative represented by the general formula (3) can be suitably produced.

[0019]

Embedded image

Next, as shown below, the triindole derivative represented by the general formula (3) is
By introducing a formyl group by the r (Vilsmeier) reaction, a triindole derivative represented by the general formula (4) can be produced. First, dimethylformamide is reacted with phosphorus oxychloride to form a Vilsmeier complex. The reaction temperature is 0.degree.
Let react for minutes. The reaction solution is dissolved in 1,2-dichloroethane, and a triindole derivative represented by the general formula (3) is added to perform formylation. Reaction temperature is 70 ° C
The reaction time is preferably 12 hours or more. The product is hydrolyzed by adding water, and then purified by column chromatography. As described above, the triindole derivative represented by the general formula (4) can be suitably produced.

[0021]

Embedded image

Specific examples of the triindole derivative represented by the general formula (4) include the following compounds.

Embedded image

Next, a general synthetic scheme of a polymer comprising a triindole derivative from the triindole derivative represented by the general formula (4) is shown below. In [Chemical formula 7], the case where all of the formyl groups are at the para-position (p-position) will be particularly described.

[0024]

Embedded image

Crosslinking with disubstituted formyl of triindole
Molecular NCCH_TwoCOOR^TwoOCOCH _TwoCN and Knobena
Polymerization is performed by gel condensation. Triindole 2
Substituted formyl compound and cross-linking molecule NCCH_TwoCOOR^TwoOCOC
H_TwoCN, dimethylaminopyridine as base, molar ratio
1: 1: 2 in tetrahydrofuran solution, in nitrogen atmosphere
React at 50 ° C for 1 hour. Evaporate from this reaction solution
The solvent is distilled off using a rotator. Tetrahydrofuran
To dissolve the product and use an evaporator.
And the solvent is distilled off. This operation is repeated five times. to this
Therefore, the degree of polymerization increases. Finally, tetrahydrofuran
To purify the desired polymer by reprecipitation with methanol
Can be.

The polymer comprising the triindole derivative of the present invention has photorefractive properties. The photorefractive effect is a phenomenon in which the spatial charge distribution inside a substance changes due to irradiation of spatially non-uniform light such as interference fringes. It refers to the phenomenon of modulation. Utilizing this phenomenon, applications such as amplification of coherent images, optical limiters, novelty filters, and self-excited phase conjugate systems are currently being proposed. The generation of photorefractive effect includes generation of carriers by photoexcitation,
Carrier transport, carrier capture (formation of spatial electric field),
The existence of the electro-optic effect is required. In the organic photorefractive material, the function of the elementary process described above is realized by combining a photoconductive material and a second-order nonlinear optical material.

As the organic photorefractive material,
A multi-component polymer material obtained by doping a second-order nonlinear material with a hole transporting agent or a sensitizer for generating a photocarrier is generally used. . Although many materials having high performance have been found so far in a multi-component system, they involve various problems such as phase separation and crystallization due to high concentration doping. Therefore, in practical use, a polymer of a single-component photorefractive material is excellent in ease of thin film fabrication, reproducibility, and material stability.

[0028]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. [Triindole derivative represented by the general formula (3)] -Synthesis of octyloxindole- 25 g of oxindol, 100 g of 1-iodooctane,
150 g of potassium carbonate and 1.5 g of 18-crown-6-ether were refluxed overnight in a tetrahydrofuran solvent under a nitrogen atmosphere. After the reaction solution was filtered and the solvent was distilled off from the filtrate, column chromatography (silica gel,
Purification with eluent: dichloromethane) gave octyloxindole (18.1 g; yield 39%).
The result of NMR of the obtained octyloxindole is shown. ¹ H NMR (300 MHz, CDCl ₃ , TMS):
_{0.81-0.89 (m, 3H, CH 3} ), 1.14-
_{1.33 (m, 10H, CH 2} ), 1.67 (quin
t. , J = 7.5 Hz, 2H, CH ₂ ), 3.51
_{(S, 2H, CH 2)} , 3.69 (t, J = 7.2H
_{z, 2H, NCH 2),} 6.82 (d, J = 8.1H
z, 1H, Charom), 7.02 (t, J = 8.1).
Hz, 1H, Charom), 7.22-7.28.
(M, 2H, Charom).

Synthesis of Trioctylindole 18.1 g of the obtained octyloxindole was stirred overnight at 100 ° C. in air using 100 ml of phosphorus oxychloride as a solvent. After the reaction solution was slowly poured into ice to crush phosphorus oxychloride, the solution was neutralized with an aqueous sodium hydroxide solution. After the compound was extracted from this solution with chloroform, it was dried over magnesium sulfate overnight. After removing magnesium sulfate by filtration, the solvent was distilled off from the filtrate and column chromatography (silica gel, eluent:
Purification with dichloromethane-hexane (1: 9) yielded trioctylindole (a triindole derivative represented by the general formula (1)) (4.8 g; yield: 10%). NMR of the obtained trioctylindole
The result is shown.

¹ H NMR (300 MHz, CDCl ₃ ,
TMS): 0.82 (t, J = 7.8 Hz, 9H, CH
_{3), 1.18-1.27 (m, 30H} , CH 2), 1.
_{99 (br, 6H, CH 2} ), 4.92 (t, J = 9.
0 Hz, 6H, NCH ₂ ), 7.33 (t, J = 8.7)
Hz, 3H, Charom), 7.45 (t, J = 9.
0 Hz, 3H, Charom), 7.63 (d, J =
9.0 Hz, 3H, Charom), 8.28 (d, J
= 9.0 Hz, 3H, Charom): m / z (FAB
-MS) 682 (MH ^<+> ). Elemental an
analysis calcd for C ₄₈ H ₆₃ N
₃ (%): C84.53, H9.31, N6.16; f
sound: C84.44, H9.37, N6.13.

[Triindole Derivative Represented by the General Formula (4)] The obtained trioctylindole was formylated to produce a triindole derivative represented by the general formula (4). Under a nitrogen atmosphere, 25 ml of dimethylformamide dehydrated at 0 ° C. was reacted with 7 ml of phosphorus oxychloride. 3. After stirring for 30 minutes, the above trioctylindole dissolved in 50 ml of dichloroethane.
8 g was slowly dropped into the reaction solution. 70 ° C
After stirring overnight at, water was added to hydrolyze, followed by extraction with chloroform. After drying over magnesium sulfate overnight, the mixture was filtered, the solvent was distilled off from the filtrate, and the residue was purified by column chromatography (silica gel, eluent: dichloromethane) to obtain the following disubstituted formyl trioctylindoles 3a (0.83 g; 16% yield), 3
b (0.95 g; 18% yield), 3c (1.20 g; 23% yield), and 3d (0.55 g; 11% yield) were obtained. At this time, as a by-product, monosubstituted formyl compounds 2a and 2b of trioctylindole shown below were obtained, but these could not be separated and purified by column chromatography.

[0032]

Embedded image

The NMR results of the obtained 3d disubstituted formyl trioctylindole are shown. ¹ H NMR (300 MHz, CDCl ₃ , TMS):
_{0.79-0.95 (m, 9H, CH 3} ), 1.22-
1.40 (m, 30H, CH ₂ ), 1.99 (br, 6
_{H, CH 2), 4.84-4.97 (} m, 6H, NC
H ₂ ), 7.29 (t, J = 7.2 Hz, 1H, CHa)
rom), 7.42 (t, J = 7.2 Hz, 1H, CH
arom), 7.52-7.56 (m, 2H, Char)
om), 7.73 (d, J = 8.1 Hz, 1H, CHa
rom), 7.86 (d, J = 8.4 Hz, 1H, CH
arom), 7.95 (s, 1H, CHarom),
8.11 (d, J = 7.8 Hz, 1H, Caro
m), 8.17 (d, J = 8.4 Hz, 1H, Char
om), 8.56 (s, 1H, Charom), 10.
03 (s, 1H, CHO), 10.08 (s, 1H, C
HO): m / z (FAB-MS) 738 (MH ^<+> ).

<Formation of Crosslinked Molecules> EDC- which is a dehydrating agent
HCl (1-ethyl-3- (3-dimethylaminopropyl) carbodidiimide hydrochloride (17.8 g) was dissolved in 100 ml of dichloromethane under a nitrogen atmosphere, and triethylamine (18.82 g) was added thereto, followed by stirring. .
To this solution were added cyanoacetic acid (7.90 g) and hexamethylene glycol (2.74 g), and the mixture was refluxed overnight. The reaction solution was sucked, washed with a dilute hydrochloric acid aqueous solution and water, dried over magnesium sulfate, and then the solvent was distilled off. The obtained product was recrystallized twice with acetone / hexane to obtain a crosslinked molecule NCCH ₂ COO (CH ₂ ) ₆ OCOCH ₂ CN.

(Formation of polymer) The disubstituted formyl derivative of a triindole derivative (500 mg) and the above-mentioned NCCH ₂
COO (CH ₂ ) ₆ OCOCH ₂ CN and dimethylaminopyridine were reacted in a tetrahydrofuran solvent at 50 ° C. for 1 hour, and the solvent was distilled off. After a small amount of trahydrofuran was added to dissolve the product, the solvent was distilled off using an evaporator. This operation is repeated five times. Finally, the target polymer was purified by reprecipitation with tetrahydrofuran and methanol. The degree of polymerization of the obtained polymer was determined by GPC. Average molecular weight about 10,000 (n = 10)

FIG. 2 shows the absorption spectrum of the obtained polymer. In FIG. 2, for comparison, triindole is indicated by a dotted line, and the polymer is indicated by a solid line. The samples were each dissolved in chloroform at 10 ^-5 mol / l. In the case of triindole, intramolecular π-π ^* absorption was observed at around 320 nm. On the other hand, in the polymer, large absorption due to charge transfer absorption from triindole to the acceptor site of the crosslinked molecule was observed at 435 nm together with intramolecular π-π ^* absorption.

Next, the photorefractive property of the obtained polymer was measured. FIG. 3 and FIG. 4 show the results measured using the two-light-wave coupling method. A 532 nm wavelength Nd: YAG laser was used as a light source. FIG. 3 shows a result obtained by dividing a laser beam into two by a beam splitter, intersecting the beam on the sample at an intersection angle of 10.8 °, and measuring each transmitted light by a photodiode. When two light waves are irradiated on the photorefractive material, a diffraction grating (grating) having a refractive index is formed from interference fringes of the two light waves. In the photorefractive effect, since the refractive index grating is formed simultaneously with the irradiation of light, the writing light itself is diffracted, and the amplitude of the two incident lights changes with the progress of the light.

The incidence at 0 seconds in FIG. 3 shows that a grating is formed with the passage of time, and that asymmetrical energy coupling unique to the photorefractive effect occurs. Such a shift in power due to the phase shift can be regarded as amplifying one lightwave with the other, and the magnitude is defined as an amplification gain Γ. The amplification gain Γ determined in this triindole polymer about 100 cm ^- 1. The amplification gain の of the polymer in which the triindole moiety was replaced with carbazole was 31
Since it is cm ^- 1, the polymer of triindole shows about three times the amplification effect of the polymer containing carbazole. The response speed of the polymer containing carbazole was 14
Minutes, whereas the polymer containing triindole took about 5 minutes, and an increase in response speed was also observed. It is considered that the increase in the amplification gain Γ and the response speed are caused by an increase in the hole transport ability due to an increase in the donor property and planarity of triindole.

FIG. 4 shows a change in light intensity when the sample is moved by the piezo element. After writing the diffraction grating with two beams on the photorefractive medium, the position of the sample was moved at a high speed with a piezo stage to intentionally provide a phase shift between the incident light and the diffraction grating. The transmitted light (fringe pattern) of the diffraction grating at that time was observed.
FIG. 4 shows that the phase shift is 90 °, and in this compound, the carrier diffusion process is a dominant photorefractive effect as in the case of a polymer containing a carbazole skeleton.

[0040]

As described above, according to the present invention, amorphousness can be stably exhibited and a thin film can be formed. For example, a photoconductive material, a nonlinear optical material, a photorefractive (PR) material, Luminescence (E
L) A useful polymer for the material can be provided.
Further, according to the optical element of the present invention, it is possible to provide an optical element having excellent optical characteristics by using a polymer having the above-mentioned characteristics.

[Brief description of the drawings]

FIG. 1 shows the results of molecular orbital calculations of trimethylindole and methylcarbazole using MOPAC.

FIG. 2 is a view showing an absorption spectrum of a polymer comprising a triindole derivative of the present invention.

FIG. 3 shows a beam crossing angle of 10.8 ° on a sample according to the invention.
FIG. 4 is a diagram in which each transmitted light is measured by a photodiode at the intersection.

FIG. 4 is a diagram showing a change in light intensity when a sample of the present invention is moved by a piezo element.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 33/22 H01L 31/08 T // C07D 487/14 F term (Reference) 3K007 AB01 DA00 DB03 EB00 FA01 4C050 AA01 AA08 BB04 CC04 DD01 EE03 FF05 GG01 HH01 4J033 GA01 GA11 HB10 5F088 AA11 AB11 BA15 CB18

Claims (3)

[Claims] 1. A polymer comprising a triindole derivative represented by the following general formula (1). Embedded image <In the general formula (1), R ¹ represents a linear or branched alkyl group having 1 to 14 carbon atoms, and R ² represents 2 to 1 carbon atoms.
4 represents a linear or branched alkyl group, and n represents 5 to 15. ) 2. In the general formula (1), R ¹ represents a linear or branched alkyl group having 1 to 8 carbon atoms, and R ² represents a linear or branched alkyl group having 4 to 10 carbon atoms. , N represents 8 to 12, wherein the polymer comprises a triindole derivative according to claim 1. 3. An optical element comprising a polymer comprising the triindole derivative according to claim 1 or 2.