JP4139903B2 - Fused ring polythiophene-S, S-dioxide and method for producing the same - Google Patents

Description

  The present invention relates to a condensed ring polythiophene-S, S-dioxide and a method for producing the same.

In the field of organic electronics such as organic thin film transistors (FETs) and organic electroluminescent devices (EL devices), many materials showing p-type charge transport properties are known. On the other hand, excellent n-type charge transport materials are still limited, and new substances are being searched for all over the world. In the molecular design of such materials, it is important how to make a material having a highly planar π-conjugated skeleton taking into account effective intermolecular interactions and having a high electron accepting ability. As a structural modification to improve electron accepting ability, it was common to introduce an electron withdrawing group such as fluorine into a π-conjugated skeleton, but in recent years, a chain-like oligosaccharide in which carbons contained in adjacent thiophenes are bonded together. In thiophene, it has been reported that the electron accepting ability is improved when some thiophene skeletons are partially converted into thiophene dioxide (see Non-Patent Document 1).
Advanced Materials, Vol10, No.7, pp551-554 (1998)

  By the way, in the molecular design of an excellent n-type charge transport material, it is important to construct a highly planar π-conjugated skeleton in addition to having a high electron accepting ability. Since the ring is connected by a C—C single bond, it can take a twisted structure and does not become a highly planar π-conjugated skeleton. For this reason, development of an n-type charge transporting material having a high electron accepting ability and a highly planar π-conjugated skeleton is desired.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a condensed polythiophene-S, S-dioxide having a high electron accepting ability and a highly planar π-conjugated skeleton. To do. Another object is to provide a method for efficiently producing such S, S-dioxide.

  As a result of intensive studies to solve the above-described problems, the present inventors have completed the present invention.

That is, the condensed ring polythiophene-S, S-dioxide of the present invention is one in which at least one sulfur contained in the condensed ring polythiophene represented by the formula (1a) or (1b) is oxidized to a dioxide. Here, in the formula (1a) and the formula (1b), R is hydrogen, a trialkylsilyl group, an alkyl group having 1 to 18 carbon atoms, an alkyl group having 1 to 18 carbon atoms, and all or part of the hydrogen atoms are Fluoroalkyl group substituted by fluorine, alkoxy group, alkylthio group, aryloxy group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, alkenyl group, alkynyl group, allyl group, amino group, N-alkylamide Group, alkanecarboxamide group, azo group, carboxyl group, acyl group, alkoxycarbonyl group, formyl group, nitro group, cyano group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, alkylsulfonyloxy group, halogen atom , Aryl group, oligoaryl group, monovalent heterocyclic group Or a monovalent oligo heterocyclic group, n is an integer.

  The condensed polythiophene represented by the formulas (1a) and (1b) exhibits p-type charge transport properties, but the condensed polythiophene-S, S-dioxide of the present invention obtained by oxidizing them exhibits n-type charge transport properties, High electron acceptability. Here, an example in which the energy levels of HOMO-LUMO of fused polythiophene and its S, S-dioxide are compared is shown in FIG. FIG. 1 shows that the energy level of HOMO-LUMO is reduced to n-type by oxidizing p-type fused-ring polythiophene. Further, the condensed polythiophene represented by the formulas (1a) and (1b) can be said to be a π-conjugated electron compound having high planarity from the result of X-ray structural analysis. Since S, S-dioxide has the same basic skeleton, it can be said to be a π-conjugated electron compound having high planarity. Therefore, the condensed polythiophene-S, S-dioxide of the present invention is useful as an organic electronic material such as an FET or an EL element.

  In the condensed ring polythiophene-S, S-dioxide of the present invention, R is hydrogen, a trialkylsilyl group, an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms, and all or a part of hydrogen atoms are present. Fluoroalkyl group substituted by fluorine, alkoxy group, alkylthio group, aryloxy group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, alkenyl group, alkynyl group, allyl group, amino group, N-alkylamide Group, alkanecarboxamide group, azo group, carboxyl group, acyl group, alkoxycarbonyl group, formyl group, nitro group, cyano group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, alkylsulfonyloxy group, halogen atom, Aryl group, oligoaryl group, 1 It is a heterocyclic group, or a monovalent oligo heterocyclic group. Among these, as the trialkylsilyl group, all three alkyl groups may be the same, or all may be different, or only one may be different. For example, a trimethylsilyl (TMS) group, triisopropylsilyl ( TIPS) group, tri-tert-butylsilyl (TTBS) group, tert-butyldimethylsilyl (TBDMS) group and the like. In addition, the alkyl group having 1 to 18 carbon atoms may be linear or branched, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl. Group, tert-butyl group, hexyl group, octyl group, dodecyl group and the like. In addition, such an alkyl group having 1 to 18 carbon atoms in which all or part of hydrogen is substituted with fluorine includes a perfluoroalkyl group in which all hydrogen is substituted with fluorine, or only terminal hydrogen is fluorine. Examples include substituted alkyl groups. In addition, you may use the above-mentioned C1-C18 alkyl group as alkyl of a trialkylsilyl group.

  In the condensed polythiophene-S, S-dioxide of the present invention, R is a trialkylsilyl group, an alkyl group having 1 to 18 carbon atoms, an alkyl group having 1 to 18 carbon atoms, and all or part of hydrogen is fluorine. A substituted one is preferred. This increases the solubility in organic solvents. When the solubility in an organic solvent is increased, a purification operation such as column chromatography becomes possible, and the purity can be sufficiently increased. In addition, it becomes easy to apply to FETs and EL devices in which the purity of the compound is said to greatly affect the performance. Further, when applied to an FET or EL element, it may be possible to form a film by dissolving a condensed polythiophene-S, S-dioxide in an organic solvent, which is also suitable for such film formation.

Examples of the condensed polythiophene-S, S-dioxide of the present invention are shown in formulas (2) to (5). Note that R in each formula is as described above.

  The condensed ring polythiophene-S, S-dioxide of the present invention is obtained by reacting the condensed ring polythiophene represented by the above formula (1a) or (1b) with a peroxide to contain at least one of the condensed ring polythiophenes. It can be produced by oxidizing sulfur to a dioxide. Here, the peroxide is not particularly limited, and examples thereof include m-CPBA, benzoyl peroxide, hydrogen peroxide solution, and peracetic acid. The number of moles of peroxide to be used may be determined by how many sulfur contained in the condensed polythiophene are oxidized into a peroxide. For example, when one sulfur is oxidized into a peroxide, about 2 moles of peroxide is used. That's fine. Moreover, the sulfur contained in the condensed polythiophene may be oxidized step by step to a dioxide, or a plurality of sulfur may be oxidized to a dioxide at a time. In addition, what is necessary is just to set reaction conditions, such as a reaction solvent, reaction temperature, and reaction time suitably according to the reaction substrate, reagent, etc. to be used.

Next, an example of a method for producing an organic thin film transistor using the condensed ring polythiophene-S, S-dioxide of the present invention will be described. First, an n-type silicon substrate having a silicon oxide film as an insulating layer is subjected to ultrasonic cleaning with a neutral detergent diluted with pure water, and then the detergent is removed by ultrasonic cleaning in pure water. Thereafter, ultraviolet irradiation cleaning is performed with an ultraviolet-ozone cleaner. A thin film of S, S-dioxide of the present invention is formed on the substrate thus cleaned by vacuum deposition. As the S, S-dioxide, it is preferable to use a high-purity product obtained by repeating the purification operation several times. The vacuum deposition conditions are such that the substrate is fixed above the deposition boat, the substrate temperature is adjusted to −100 to −150 ° C., and the degree of vacuum is reduced to the order of 10 ⁻⁶ Torr. Thereafter, vacuum deposition is performed so that a desired thickness (for example, 50 nm) is obtained at a rate of several nm to several tens of nm per minute. Subsequently, a gold electrode is vacuum deposited as a source electrode and a drain electrode. Furthermore, N-methyl-3,4,9,10-tetracarboxylic acid diimide is vacuum-deposited at a rate of several nm per minute so as to have a desired thickness (for example, 50 nm). Although an organic thin film transistor can be manufactured in this manner, it may be manufactured by other methods.

  The best mode for carrying out the present invention will be described below with reference to examples.

[Examples 1 and 2]
By using 2-ethynyl-3-bromothiophene as a starting material, copper iodide-catalyzed oxidative coupling, and subsequent reaction of lithium diisopropylamide with triisopropylsilyl chloride, 1,4-bis [3-bromo- 5- (Triisopropylsilyl) thienyl] -1,3-butadiene was obtained. Further, this was dilithiated, reacted with sulfur, and then compound 1 was synthesized by desulfurization reaction with copper. M-CPBA (2 mol. Amt.) Was added to a solution of Compound 1 (100 mg, 0.161 mmol) in dichloromethane (10 ml), and the mixture was stirred under the reaction conditions described in Examples 1 and 2 in Table 1. The solution was washed sequentially with saturated aqueous NaHCO ₃ solution, H ₂ O, and aqueous NaCl solution and extracted with dichloromethane, and then the organic layer was dried over MgSO ₄ , filtered, and the solvent was distilled off. By purification by flash column chromatography (SiO ₂ / CH ₂ Cl ₂ : Hexane = 1: 2), S, S-dioxide (R _f = 0.5) of Compound _{2 of the following} Chemical Formula 6 and S, S of Compound 3 -Dioxide ( _Rf = 0.23) was obtained. The results of Examples 1 and 2 are shown in Table 1.

The spectral data of Compound 2 is as follows. ¹ H-NMR; δ 7.39 (2H, s, arom), 1.56-1.35 (6H, m, CH), 1.18-1.15 (36H, d, CH ₃ ) .EI-MS; m / e = 652 [M ⁺ ].

The spectral data of Compound 3 is as follows. ¹ H-NMR; δ 7.43, 7.33 (2H, s, arom), 1.43-1.31 (6H, m, CH), 1.17-1.16 (18H, d, CH ₃ ), 1.14-1.13 (18H, d, CH ₃ ). EI-MS; m / e = 652 [M ⁺ ].

[Examples 3 to 5]
M-CPBA (144 mg, 0.644 mmol) was added to a solution of compound 1 (100 mg, 0.161 mmol) in dichloromethane (10 ml), and the mixture was stirred under the reaction conditions described in Examples 3 to 5 in Table 1. The solution was washed with saturated aqueous NaHCO ₃ solution, H ₂₀ , aqueous NaCl solution and extracted with dichloromethane. It was dried with MgSO ₄ , filtered and evaporated. Purification by flash column chromatography (SiO ₂ / CH ₂ Cl ₂ : Hexane = 1: 2) and further purification by preparative GPC (CHCl ₃ ) gave compounds 2, 3, 4, and 5 of the following chemical formula 7. The results of Examples 3 to 5 are shown in Table 1.

The spectral data of Compound 4 is as follows. ¹ H-NMR; δ 7.34 (2H, s, arom), 1.41-1.26 (6H, m, CH), 1.14-1.12 (36H, d, CH ₃ ) .EI-MS; m / e = 684 (M ⁺ ].

The spectral data of Compound 5 is as follows. ¹ H-NMR; δ 7.34, 7.21 (2H, s, arom), 1.41-1.26 (6H, m, CH), 1.23-1.20 (18H, d, CH ₃ ), 1.15-1.13 (18H, d, CH ₃ EI-MS; m / e = 684 [M ⁺ ]. Anal. Calcd for C ₃₀ H ₄₄ O ₄ S ₅ Si ₂ : C, 52.59; H, 6.47. Found: C, 52.81; H, 6.48.

[Example 6]
M-CPBA (2.6 mol. Amt.) Was added to a solution of compound 3 (100 mg, 0.153 mmol) in dichloromethane (10 ml), and the mixture was stirred at room temperature for 80 hours. The solution was washed with saturated aqueous NaHCO ₃ solution, H ₂ O, aqueous NaCl solution and extracted with dichloromethane. It was dried with MgSO ₄ , filtered and evaporated. Using preparative TLC (CH ₂ Cl ₂ : hexane = 1: 1), compounds 4 and 5 shown in the following chemical formula 8 were obtained. The results of each example are shown in Table 1.

  Here, the cyclic voltammetry graph of Compound 1 and Compound 4 is shown in FIG. 2, and the cyclic voltammetry graph of Compound 3 is shown in FIG. As can be seen from FIGS. 2 and 3, Compound 1 showed a reversible oxidation wave at 0.63 V (vs Fc / Fc +), whereas Compound 3 in which one sulfur of the condensed polythiophene was oxidized to a dioxide. An oxidation wave was shown at 0.95 V, a reduction wave was shown at −1.86 V, and a reduction wave was shown at −1.67 V in Compound 4 in which two sulfurs of the condensed polythiophene were oxidized to oxides. Thus, it was found that the electron acceptability increases as the oxidation proceeds.

  In addition, this invention is not limited to the above Example at all, As long as it belongs to the technical scope of this invention, it can implement in a various aspect.

It is explanatory drawing of the energy level of HOMO-LUMO. 2 is a graph of cyclic voltammetry of compounds 1 and 4. 2 is a graph of cyclic voltammetry of Compound 3.

Claims (2)

A condensed polythiophene-S, S-dioxide represented by the following formula:

(In the above formula , R is hydrogen, a trialkylsilyl group, an alkyl group having 1 to 18 carbon atoms, an alkyl group having 1 to 18 carbon atoms, and all or a part of hydrogen is substituted with fluorine, Alkoxy group, alkylthio group, aryloxy group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, alkenyl group, alkynyl group, allyl group, amino group, N-alkylamide group, alkanecarboxamide group, azo group, Carboxyl group, acyl group, alkoxycarbonyl group, formyl group, nitro group, cyano group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, alkylsulfonyloxy group, halogen atom, aryl group, oligoaryl group, monovalent Heterocyclic group or monovalent oligoheterocyclic ring Der Ru) The manufacturing method of the condensed polythiophene-S, S-dioxide which oxidizes to the condensed polythiophene-S, S-dioxide of Claim 1 by making the condensed polythiophene represented by a following formula react with a peroxide.

(In the above formula , R is hydrogen, a trialkylsilyl group, an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms, and all or a part of hydrogen is substituted with fluorine. , Alkoxy group, alkylthio group, aryloxy group, arylthio group, arylalkyl group, arylalkoxy group, arylalkylthio group, alkenyl group, alkynyl group, allyl group, amino group, N-alkylamide group, alkanecarboxamide group, azo group Carboxyl group, acyl group, alkoxycarbonyl group, formyl group, nitro group, cyano group, boryl group, phosphino group, silyloxy group, arylsulfonyloxy group, alkylsulfonyloxy group, or halogen atom, aryl group, oligoaryl group, Monovalent heterocyclic group or monovalent o Ru Gore-heterocyclic group Der)

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