JPWO2012081614A1 - Pyrrole compounds and uses thereof - Google Patents

Abstract

The present invention provides a compound having excellent photoelectric conversion characteristics and useful as a photoelectric conversion dye. The compound according to the present invention is a pyrrole compound represented by the following general formula (1), a tautomer or stereoisomer thereof, or a salt thereof. In the general formula (1), R1 to R4 each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group; Z represents a group having an acidic group; Z represents a linking group having at least one heterocyclic ring selected from the group consisting of a thiophene ring, a furan ring and a pyrrole ring.

Description

  The present invention relates to a pyrrole compound and its use.

Due to the large amount of fossil fuels represented by petroleum so far, global warming has become a serious problem due to the increase in CO ₂ concentration, and there is a concern about the depletion of fossil fuels. Therefore, how to meet future demand for large amounts of energy has become a very important issue on a global scale. Under such circumstances, the use of light energy that is infinite and clean with respect to nuclear power generation is being actively studied. Solar cells that convert light energy into electrical energy include inorganic solar cells that use inorganic materials such as single crystal silicon, polycrystalline silicon, and amorphous silicon, and organic solar cells that use organic dyes and conductive polymer materials. Solar cells have been proposed.

  Under such circumstances, a dye-sensitized solar cell (Gretzel solar cell) proposed by Dr. Gretzell of Switzerland in 1991 (for example, see Patent Document 1 and Non-Patent Document 1) is a simple manufacturing process. In addition, it is expected to be a next-generation solar cell because it can achieve the same conversion efficiency as amorphous silicon. A Gretzel type solar cell includes a semiconductor layer having a dye adsorbed thereon, a semiconductor electrode formed on a conductive substrate, a counter electrode made of a conductive substrate opposite to the semiconductor electrode, and an electrolyte held between the electrodes. With layers.

  In this Gretzel type solar cell, the adsorbed dye absorbs light and enters an excited state, and electrons are injected from the excited dye into the semiconductor layer. The dye that has been oxidized by the emission of electrons is reduced by the transfer of electrons to the dye by the oxidation reaction of the redox agent in the electrolyte layer, and returns to the original dye. Then, the redox agent that has donated electrons to the dye is reduced again on the counter electrode side. The Gretzel type solar cell functions as a solar cell that converts light energy into electric energy by this series of reactions.

  In this Gretzel-type solar cell, the surface area on which the dye is adsorbed, that is, the effective reaction surface area is increased by about 1000 times by using porous titanium oxide obtained by sintering fine particles in the semiconductor layer. . Compared with the case of using a titanium oxide film produced by a vapor phase growth method, the use of porous titanium oxide has a great feature that a larger photocurrent can be taken out.

  In a Gretzel type solar cell, a metal complex such as a ruthenium complex is used as a sensitizing dye. Specifically, for example, cis-bis (isothiocyanato) -bis- (2,2′-bipyridyl-4,4′-dicarboxylic acid) is used. Acid) ruthenium (II) ditetrabutylammonium complex, cis-bis (isothiocyanato) -bis- (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium (II), etc., ruthenium bipyridine complex, ruthenium Tris (isothiocyanato) (2,2 ′: 6 ′, 2 ″ -terpyridyl-4,4 ′, 4 ″ -tricarboxylic acid) ruthenium (II) tritetrabutylammonium complex is used.

Japanese Patent No. 2664194

Nature 353, (1991), 737-740.

  As described above, in the dye-sensitized solar cell described in the background art, a metal complex containing a noble metal such as a ruthenium complex is used as a sensitizing dye. For example, when mass-producing dye-sensitized solar cells using a ruthenium complex, ruthenium has many uses such as a catalyst, and thus there is a possibility that a problem may arise in terms of “resource constraints”. Further, since noble metals are used, the dye-sensitized solar cell becomes expensive and hinders its spread. For this reason, development of the organic dye which does not contain noble metals, such as ruthenium, is calculated | required as a sensitizing dye used for a dye-sensitized solar cell. In general, compared to metal complexes such as ruthenium complexes, organic dyes have a large molar extinction coefficient and also have a high degree of freedom in molecular design, and therefore, development of organic dyes with high photoelectric conversion efficiency is expected.

  The present invention has been made in order to solve the above-described problems, and is a pyrrole compound that is excellent in photoelectric conversion characteristics and can be used for a pigment for photoelectric conversion, and a photoelectric conversion characteristic that is excellent in photoelectric conversion characteristics including the pyrrole compound. It is in providing the pigment | dye for conversion, the semiconductor electrode for photoelectrochemical cells using the same, the photoelectric conversion element for photoelectrochemical cells, and a photoelectrochemical cell.

The pyrrole compound of the present invention is
A pyrrole compound represented by the following general formula (1), a tautomer or stereoisomer thereof, or a salt thereof.

一般式（１）中、
Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表し、
Ｘは、酸性基を有する基を表し、
Ｚは、チオフェン環、フラン環およびピロール環からなる群から選択される少なくとも一種の複素環を有する連結基を表す。

In general formula (1),
R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group,
X represents a group having an acidic group,
Z represents a linking group having at least one heterocyclic ring selected from the group consisting of a thiophene ring, a furan ring and a pyrrole ring.

The dye for photoelectric conversion of the present invention is
It includes at least one of a pyrrole compound represented by the general formula (1), a tautomer or stereoisomer thereof, or a salt thereof according to the present invention.

  The semiconductor electrode for photoelectrochemical cells of the present invention is characterized by having a semiconductor layer containing the photoelectric conversion dye of the present invention.

  The photoelectric conversion element for a photoelectrochemical cell of the present invention has the semiconductor electrode for a photoelectrochemical cell of the present invention.

  Moreover, the photoelectrochemical cell of the present invention is characterized by having the photoelectric conversion element for a photoelectrochemical cell of the present invention.

  According to the present invention, a pyrrole compound usable for a photoelectric conversion dye excellent in photoelectric conversion characteristics, a photoelectric conversion dye excellent in photoelectric conversion characteristics containing the pyrrole compound, and a photoelectrochemical cell using the same Semiconductor electrodes, photoelectric conversion elements for photoelectrochemical cells, and photoelectrochemical cells can be provided.

FIG. 1 is a cross-sectional view schematically showing a configuration of an example of a photoelectric conversion element for a photoelectrochemical cell of the present invention. FIG. 2 is a graph showing an absorption spectrum of the pyrrole compound (PY-1) of the first embodiment.

  In addition, the code | symbol attached | subjected in FIG. 1 means the following, respectively.

DESCRIPTION OF SYMBOLS 1 Semiconductor layer 2 Transparent conductive layer 3 Light transmissive substrate 4 Semiconductor electrode for photoelectrochemical cells 5 Electrolyte layer (charge transport layer)
6 Catalyst layer 7 Substrate 8 Counter electrode

  Hereinafter, the present invention will be described in detail with reference to examples.

<Pyrrole compound>
The pyrrole compound of the present invention is, as described above, a pyrrole compound represented by the following general formula (1), a tautomer or stereoisomer thereof, or a salt thereof.

前記一般式（１）中、
Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表し、
Ｘは、酸性基を有する基を表し、
Ｚは、チオフェン環、フラン環およびピロール環からなる群から選択される少なくとも一種の複素環を有する連結基を表す。

In the general formula (1),
R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group,
X represents a group having an acidic group,
Z represents a linking group having at least one heterocyclic ring selected from the group consisting of a thiophene ring, a furan ring and a pyrrole ring.

  In addition, it is preferable that the pyrrole ring utilized for the structure of Z has a structure of 1H-pyrrole among three isomers of 1H-pyrrole, 2H-pyrrole, and 3H-pyrrole.

  When the pyrrole compound of the present invention has isomers such as tautomers or stereoisomers (eg, geometrical isomers, conformational isomers and optical isomers), any isomers of the present invention Can be used. The salt of the pyrrole compound of the present invention may be an acid addition salt or a base addition salt. Furthermore, the acid forming the acid addition salt may be an inorganic acid or an organic acid, and the base forming the base addition salt may be an inorganic base or an organic base. The inorganic acid is not particularly limited. For example, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, hypofluorite, hypochlorous acid, hypobromite, Hypoiodous acid, fluorinated acid, chlorous acid, bromic acid, iodic acid, fluoric acid, chloric acid, bromic acid, iodic acid, perfluoric acid, perchloric acid, perbromic acid, periodic acid, etc. Can be mentioned. The organic acid is not particularly limited, and examples thereof include p-toluenesulfonic acid, methanesulfonic acid, oxalic acid, p-bromobenzenesulfonic acid, succinic acid, citric acid, benzoic acid, and acetic acid. The inorganic base is not particularly limited, and examples thereof include ammonium hydroxide, alkali metal hydroxides, alkaline earth metal hydroxides, carbonates and hydrogen carbonates, and more specifically, for example, Examples thereof include sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydroxide and calcium carbonate. The organic base is not particularly limited, and examples thereof include alcohol amine, trialkylamine, tetraalkylammonium, and tris (hydroxymethyl) aminomethane. Examples of the alcohol amine include ethanolamine. Examples of the trialkylamine include trimethylamine, triethylamine, tripropylamine, tributylamine, and trioctylamine. Examples of the tetraalkylammonium include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetraoctylammonium and the like. The method for producing these salts is not particularly limited, and for example, the salt can be produced by a method such as appropriately adding the above acid or base to the pyrrole compound by a known method.

  Moreover, in this invention, carbon number of an alkyl group is 1-12, for example, Preferably it is 1-8, and carbon number of an aryl group is 5-24, for example, Preferably it is 6-12. In the case of a substituted alkyl group or a substituted aryl group, the number of carbon atoms does not include the number of carbon atoms of the substituent. In the present invention, the alkyl group specifically includes, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, Examples include hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group and the like. The same applies to a group containing an alkyl group in the structure (alkylamino group, alkoxy group, alkanoyl group, etc.). In the present invention, the substituted alkyl group may be a substituted alkyl group in which the alkyl group (unsubstituted alkyl group) is substituted with an arbitrary substituent. One or a plurality of substituents of the substituted alkyl group may be used, and when there are a plurality of substituents, they may be the same or different. Examples of the substituent of the substituted alkyl group include a hydroxy group, an alkoxy group, an aryl group (for example, a phenyl group) and the like. Specific examples of the substituted alkyl group include araalkyl groups such as a benzyl group.

  In the present invention, the aryl group includes a heteroaryl group unless specifically limited, and specifically includes, for example, a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pyrenyl group, a pyridyl group, a quinolyl group, and an acridyl group. Pyrrolyl group (1H-pyrrolyl group), furanyl group (furyl group), thienyl group, carbazoyl group, fluorenyl group and the like. In the present invention, the substituted aryl group may be a substituted aryl group in which the aryl group (unsubstituted aryl group) is substituted with an arbitrary substituent. One or a plurality of substituents of the substituted aryl group may be used, and when there are a plurality of substituents, they may be the same or different. Examples of the substituent of the substituted aryl group include an alkyl group, a hydroxy group, an alkoxy group, an amino group, an alkylamino group, and a dialkylamino group. In the present invention, specific examples of the substituted or unsubstituted aryl group include, for example, phenyl group, tolyl group, 4-t-butylphenyl group, 3,5-di-t-butylphenyl group, 4-methoxy group. Examples thereof include a phenyl group and a 4- (N, N-dimethylamino) phenyl group.

  In general, an aryl group means a monovalent group (Ar—) derived from “aromatic hydrocarbon (ArH)”, and “aromatic hydrocarbon (ArH)” includes benzene-based aromatic carbonization. Hydrogen and non-benzene aromatic hydrocarbons are included.

In the present invention, the alkenyl group may have a structure in which any carbon-carbon bond of the alkyl group is converted to a double bond by dehydrogenation. In the present invention, the acyl group is not particularly limited. For example, formyl group, acetyl group, propionyl group, isobutyryl group, valeryl group, isovaleryl group, pivaloyl group, hexanoyl group, cyclohexanecarbonyl group, benzoyl group, ethoxycarbonyl group (C ₂ H ₅ —O—CO—) and the like, and the same applies to groups containing an acyl group in the structure (acyloxy group, alkanoyloxy group, etc.). In the present invention, the carbon number of the acyl group includes carbonyl carbon. For example, an alkanoyl group having 1 carbon atom (acyl group) refers to a formyl group. In the present invention, “halogen” refers to any halogen element, and examples thereof include fluorine, chlorine, bromine and iodine.

  In the present invention, a chain group such as an alkyl group, an alkoxy group, an alkenyl group, and an alkanoyl group may be linear or branched unless otherwise limited. In the present invention, when there is an isomer due to the configuration of substituents, etc., any isomer may be used unless otherwise limited. For example, when simply referring to a “propyl group”, either an n-propyl group or an isopropyl group may be used. When simply referred to as “butyl group”, any of n-butyl group, isobutyl group, sec-butyl group and tert-butyl group may be used. When simply referred to as “naphthyl group”, either a 1-naphthyl group or a 2-naphthyl group may be used.

  X in the general formula (1) represents a group having an acidic group as described above. X may consist of only an acidic group, or may be a group in which an acidic group is bonded to another group. X is preferably an organic group having an acidic group. For example, the other group to which the acidic group is bonded may be an organic group. The organic group is not particularly limited, but is preferably a group that can be conjugated with Z. The group capable of conjugating with Z is more preferably a group having a carbon-carbon double bond. Examples of the acidic group include a carboxy group, a sulfonic acid group, a phosphonic acid group, or a salt thereof, and a carboxy group or a salt thereof is particularly preferable. When the acidic group is a salt, a monovalent or divalent metal salt, ammonium salt or organic ammonium salt is preferable. Examples of the monovalent or divalent metal salt include alkali metal salts such as Li, Na, K, and Cs, and alkaline earth metal salts such as Mg, Ca, and Sr. Examples of the organic group of the organic ammonium salt include an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, and an aryl group having 6 to 12 carbon atoms.

  The pyrrole compound represented by the general formula (1) can be adsorbed on a semiconductor layer used in a semiconductor electrode for a photoelectrochemical cell, which will be described later, because X has an acidic group.

  Specific examples of the organic group X having an acidic group are shown in the following chemical formulas (Xa) to (Xm). These organic groups X have an intercarbon (carbon-carbon) double bond in addition to an acidic group, and one bond of the linking group Z is bonded to one carbon of the carbon-carbon double bond. The other carbon is bonded to a cyano group, a carbonyl group, another carbon-carbon double bond carbon, or a carbon-nitrogen double bond carbon. However, the organic group X is not limited to these. Further, the organic group X represented by the chemical formulas (Xa) to (Xm) may be either Z-form or E-form. That is, these organic groups X may have structures as represented by chemical formulas (Xa) to (Xm) or geometric isomers thereof.

前記式（Ｘａ）〜（Ｘｍ）中、
Ｍは、水素原子または塩形成性陽イオンを表し、
Ｂ⁻は、水酸化物イオンまたは塩形成性陰イオンを表す。

In the formulas (Xa) to (Xm),
M represents a hydrogen atom or a salt-forming cation,
B ⁻ represents a hydroxide ion or a salt-forming anion.

M and B ⁻ may be monovalent ions or multivalent ions. When M or B ⁻ is a multivalent ion, the number in the chemical formulas (Xa) to (Xm) may be a fraction of the valence. For example, M may be 1 / 2Mg ²⁺ and B ⁻ may be 1 / 2SO ₄ ²⁻ , but is not limited thereto.

Examples of the salt-forming cation M include various cations capable of forming a salt (—COOM) with a carboxy group (—COO ⁻ ). Examples of such a cation include an ammonium cation (NH ⁴⁺ ); an organic ammonium cation derived from an amine (A ¹ A ² A ³ A ⁴ N ⁺ , A ^{1 to} A ⁴ represent a hydrogen atom or an organic group. At least one of which is an organic group); alkali metal ions such as Li ⁺ , Na ⁺ , K ⁺ and Cs ⁺ ; alkaline earth metal ions such as Mg ²⁺ , Ca ²⁺ and Sr ²⁺ . Examples of the organic group (A ^{1 to} A ⁴ ) of the organic ammonium cation (A ¹ A ² A ³ A ⁴ N ⁺ ) include an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, and a carbon number. Examples include 6 to 12 aryl groups.

  The organic group X having an acidic group is more preferably represented by the following chemical formulas (X1) to (X16). Further, the organic group X represented by the chemical formulas (X1) to (X16) may be either Z-form or E-form. That is, these organic groups X may have structures as represented by chemical formulas (X1) to (X16) or geometric isomers thereof.

前記有機基Ｘは、下記一般式（２）で表される基であることがさらに好ましい。

The organic group X is more preferably a group represented by the following general formula (2).

前記一般式（２）中、Ｍは、水素原子または塩形成性陽イオンを表し、前記式（Ｘａ）〜（Ｘｍ）中のＭと同様である。

In the general formula (2), M represents a hydrogen atom or a salt-forming cation, and is the same as M in the formulas (Xa) to (Xm).

  Z in the general formula (1) represents a linking group having at least one heterocyclic ring selected from a thiophene ring, a furan ring and a pyrrole ring. In addition, it is preferable that the pyrrole ring utilized for the structure of Z has a structure of 1H-pyrrole among three isomers of 1H-pyrrole, 2H-pyrrole, and 3H-pyrrole. The linking group Z is not particularly limited, but is preferably an atomic group that can be conjugated with the pyrrole ring to which Z is bonded (that is, the pyrrole ring shown in the general formula (1)). The linking group Z is preferably at least a linking group having a structure represented by the following general formula (3).

前記一般式（３）中、Ｒ^５、Ｒ^６は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換の直鎖若しくは分枝アルコキシ基を表し、Ｒ^５、Ｒ^６は互いに連結されて環を形成してもよい。なお、Ｒ^５、Ｒ^６が互いに連結されて環を形成する場合、形成される環は、５員環以上であることが好ましい。例えば、Ｒ^５、Ｒ^６が互いに連結されて環を形成する場合、形成される環を６員環以上とすることができる。置換若しくは無置換のアルキル基としては、メチル基、エチル基、プロピル基、ｎ−ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基等の炭素数１〜８のアルキル基が挙げられ、アルキル基に結合する置換基としては、ヒドロキシ基、アルコキシ基等が挙げられる。アルコキシ基としては、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基等の炭素数１〜４のアルコキシ基が挙げられる。

In the general formula (3), R ⁵ and R ⁶ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted linear or branched alkoxy group, R ⁵ and R ⁶ may be connected to each other to form a ring. When R ⁵ and R ⁶ are connected to each other to form a ring, the formed ring is preferably a 5-membered ring or more. For example, when R ⁵ and R ⁶ are connected to each other to form a ring, the formed ring can be a 6-membered ring or more. Examples of the substituted or unsubstituted alkyl group include alkyl groups having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group. Examples of the substituent bonded to the group include a hydroxy group and an alkoxy group. As an alkoxy group, C1-C4 alkoxy groups, such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, are mentioned.

  In the general formula (3), Y represents an oxygen atom, a sulfur atom or NRa, and Ra represents a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, an n-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, etc., an alkyl group having 1 to 8 carbon atoms, a benzyl group, etc. Examples of the substituent bonded to the alkyl group include a hydroxy group, an alkoxy group, and a phenyl group. Examples of the substituted or unsubstituted aryl group include phenyl group, tolyl group, 4-t-butylphenyl group, 3,5-di-t-butylphenyl group, 4-methoxyphenyl group, 4- (N, N-dimethyl group). Amino) phenyl group and the like. Examples of the substituent bonded to the aryl group include an alkyl group, a hydroxy group, an alkoxy group, and an N, N-dialkylamino group.

  Specific examples of the linking group Z are shown in the chemical formulas (Z1) to (Z20), but are not limited thereto. These examples are divalent groups having a bond in the heterocycle, and when there are multiple heterocycles, the carbons that make up the heterocycle are directly bonded to each other, or are bonded by forming a condensed ring. .

また、前記一般式（１）で表されるピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩におけるＸおよびＺの組合せとしては、例えば、下記（ａ〜ｍ）−（１〜２０）が挙げられる。下記表１−ａ〜表１−ｍ中、ＸａはＸ１〜Ｘ４に置き換えてもよく、ＸｂはＸ５に置き換えてもよく、ＸｃはＸ６に置き換えてもよく、ＸｄはＸ７に置き換えてもよく、ＸｅはＸ８に置き換えてもよく、ＸｆはＸ９に置き換えてもよく、ＸｇはＸ１０に置き換えてもよく、ＸｈはＸ１１に置き換えてもよく、ＸｉはＸ１２に置き換えてもよく、ＸｊはＸ１３に置き換えてもよく、ＸｋはＸ１４に置き換えてもよく、ＸｌはＸ１５に置き換えてもよく、ＸｍはＸ１６に置き換えてもよい。

Examples of the combination of X and Z in the pyrrole compound represented by the general formula (1), its tautomer or stereoisomer, or a salt thereof include the following (am)-(1 To 20). In the following Table 1-a to Table 1-m, Xa may be replaced with X1 to X4, Xb may be replaced with X5, Xc may be replaced with X6, and Xd may be replaced with X7. Xe may be replaced with X8, Xf may be replaced with X9, Xg may be replaced with X10, Xh may be replaced with X11, Xi may be replaced with X12, and Xj is replaced with X13 Xk may be replaced with X14, Xl may be replaced with X15, and Xm may be replaced with X16.

また、前記一般式（１）で表されるピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩におけるＲ^１〜Ｒ^４の組合せとしては、例えば、下記表２−１と表２−２に纏める、Ｒ−１〜Ｒ−７２が挙げられる。

Examples of the pyrrole compounds represented by the general formula (1), tautomers or stereoisomers thereof, or combinations of R ^{1 to} R ⁴ in the salts thereof include, for example, Tables 2-1 and 2 below. R-1 to R-72 are summarized in 2-2.

本発明のピロール系化合物は、下記一般式（４）で表わされるピロール系化合物であることがさらに好ましい。

The pyrrole compound of the present invention is more preferably a pyrrole compound represented by the following general formula (4).

前記一般式（４）中のＲ^１〜Ｒ^４は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表す。置換若しくは無置換のアルキル基としては、メチル基、エチル基、プロピル基、ｎ−ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基等の炭素数１〜８のアルキル基、ベンジル基等のアラアルキル基が挙げられ、アルキル基に結合する置換基としては、ヒドロキシ基、アルコキシ基、フェニル基等が挙げられる。置換若しくは無置換のアリール基としては、フェニル基、トリル基、４−ｔ−ブチルフェニル基、３，５−ジ−ｔ−ブチルフェニル基、４−メトキシフェニル基、４−（Ｎ，Ｎ−ジメチルアミノ）フェニル基等が挙げられ、アリール基に結合する置換基としては、アルキル基、ヒドロキシ基、アルコキシ基、Ｎ，Ｎ−ジアルキルアミノ基等が挙げられる。

R ^{1 to} R ⁴ in the general formula (4) each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group. Examples of the substituted or unsubstituted alkyl group include a methyl group, an ethyl group, a propyl group, an n-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, etc., an alkyl group having 1 to 8 carbon atoms, a benzyl group, etc. Examples of the substituent bonded to the alkyl group include a hydroxy group, an alkoxy group, and a phenyl group. Examples of the substituted or unsubstituted aryl group include phenyl group, tolyl group, 4-t-butylphenyl group, 3,5-di-t-butylphenyl group, 4-methoxyphenyl group, 4- (N, N-dimethyl group). Amino) phenyl group etc. are mentioned, As a substituent couple | bonded with an aryl group, an alkyl group, a hydroxy group, an alkoxy group, N, N- dialkylamino group etc. are mentioned.

  M in the general formula (4) represents a hydrogen atom or a salt-forming cation, and is the same as M in the formulas (Xa) to (Xm).

  Moreover, Z in the said General formula (4) is the same as Z in the said General formula (1), Preferably, the linking group containing the structure represented by the said General formula (3) is represented.

  The pyrrole compound of the present invention is particularly preferably a pyrrole compound represented by the following formula PY-1, a tautomer or stereoisomer thereof, or a salt thereof.

また、前記化合物ＰＹ−１の他には、例えば、下記表３に示す化合物ＰＹ−２〜ＰＹ−６等が特に好ましい。下記表３に、化合物ＰＹ−２〜ＰＹ−６の構造を、前記一般式（１）におけるＲ^１〜Ｒ^４、ＸおよびＺの組み合わせで示す。また、これら化合物ＰＹ−２〜ＰＹ−６は、後述の製造方法および実施例を参照することにより、当業者であれば、過度の試行錯誤や複雑高度な実験等をすることなく、化合物ＰＹ−１に準じて容易に製造し、かつ使用することができる。なお、下記表３中の化合物ＰＹ−１〜ＰＹ−６のそれぞれにおけるＸおよびＹの組み合わせは、例えば、上記表１−ａ〜表１−ｍに示す、ＸおよびＹの組み合わせのいずれかで置き換えてもよい。また、本発明のピロール系化合物は、これらの例に限定されず、Ｒ^１〜Ｒ^４、ＸおよびＺの組み合わせは任意であり、例えば、前記表１−ａ〜表１−ｍに示す任意のＸおよびＺの組み合わせと、前記表２−１と表２−２に示す任意のＲ^１〜Ｒ^４の組み合わせとを、組み合わせることが可能である。

In addition to the compound PY-1, for example, compounds PY-2 to PY-6 shown in Table 3 below are particularly preferable. Table 3 below shows the structures of the compounds PY-2 to PY-6 as a combination of R ^{1 to} R ⁴ , X and Z in the general formula (1). In addition, these compounds PY-2 to PY-6 can be obtained by referring to the production methods and examples described below, and by those skilled in the art, without undue trial and error, complicated advanced experiments, etc. 1 can be easily manufactured and used. In addition, the combination of X and Y in each of the compounds PY-1 to PY-6 in Table 3 below is replaced with, for example, any of the combinations of X and Y shown in Table 1-a to Table 1-m above. May be. Further, the pyrrole compound of the present invention is not limited to these examples, and the combination of R ^{1 to} R ⁴ , X and Z is arbitrary, for example, any of those shown in Table 1-a to Table 1-m Combinations of X and Z can be combined with any combination of R ^{1 to} R ⁴ shown in Tables 2-1 and 2-2.

本発明のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩は、例えば、光電変換特性に優れた光電変換用色素に有用であるが、これに限定されず、どのような用途に用いてもよい。

The pyrrole compound of the present invention, its tautomer or stereoisomer, or a salt thereof is useful for, for example, a photoelectric conversion dye having excellent photoelectric conversion characteristics, but is not limited thereto, and any You may use for an application.

<Method for producing pyrrole compound>
A method for producing the pyrrole compound represented by the general formula (1), a tautomer or stereoisomer thereof, or a salt thereof is not particularly limited and may be any, for example, production shown in the following scheme It may be a method. Specifically, the following scheme:
A compound represented by the following general formula (I) and a compound represented by the following general formula (II) are reacted to form a pyrrole ring to produce a pyrrole derivative represented by the following general formula (III). Pyrrole ring formation step,
Halogenating a pyrrole derivative represented by the following general formula (III) to produce a halogenated pyrrole derivative represented by the following general formula (IV),
Coupling for producing a compound represented by the following general formula (VI) by coupling a halogenated pyrrole derivative represented by the following general formula (IV) and a halide represented by the following general formula (V). Process, and
It includes an acidic group introduction step of converting Q in the following general formula (VI) to introduce acidic group X to produce a pyrrole compound represented by general formula (1).

前記一般式（Ｉ）、一般式（III）、一般式（IV）および一般式（VI）中、
Ｒ^１は、前記一般式（１）中のＲ^１と同じであり、
前記一般式（II）、一般式（III）、一般式（IV）および一般式（VI）中、
Ｒ^２〜Ｒ^４は、前記一般式（１）中のＲ^２〜Ｒ^４と同じであり、
前記一般式（IV）中、
Ｈａｌ^１は、ハロゲンであり、
前記一般式（Ｖ）中、
Ｈａｌ^２は、ハロゲンであり、
Ｈａｌ^１とＨａｌ^２は同一でも異なっていてもよく、
前記一般式（Ｖ）および一般式（VI）中、
Ｚは、前記一般式（１）中のＺと同じであり、
Ｑは、酸性基Ｘに変換可能な任意の置換基である。

In the general formula (I), general formula (III), general formula (IV) and general formula (VI),
R ¹ is the same as R ¹ in the general formula (1),
In the general formula (II), general formula (III), general formula (IV) and general formula (VI),
R ² to R ⁴ are the same as ^R 2 to R ⁴ in the general formula (1),
In the general formula (IV),
Hal ¹ is halogen,
In the general formula (V),
Hal ² is halogen,
Hal ¹ and Hal ² may be the same or different,
In the general formula (V) and the general formula (VI),
Z is the same as Z in the general formula (1),
Q is an optional substituent that can be converted to the acidic group X.

Note that Hal ¹ is a halogen selected from Cl, Br, and I; Hal ² is preferably a halogen selected from Cl, Br, and I.

In the pyrrole ring formation step, the halogenation step, the coupling step, and the acidic group introduction step, the reaction time, the reaction temperature, the amount of each reactant used, etc. are not particularly limited. For example, a known similar reaction It may be set appropriately with reference to the above. In each of the steps, a solvent, a catalyst, or the like may be appropriately used in addition to the reactants, or may not be used. For example, the pyrrole ring forming step is preferably performed in the presence of an acid catalyst. Such a pyrrole ring formation reaction is sometimes referred to as Paal-Knorr pyrrole synthesis. The halogenation step may be, for example, NBS (N-bromosuccinimide), may be performed using known halogenating agent such as Br _2. In the coupling step, from the viewpoint of yield and the like, for example, the compound of the general formula (IV) is lithiated (Hal ¹ is replaced with lithium) and then coupled with the compound of the general formula (V). You may let them. For example, a halogen selected from Cl, Br, I is adopted as Hal ¹ , and after lithiation, a halogen selected from Cl, Br, I is adopted as Hal ² of the general formula (V) It is preferable to perform a coupling reaction with the compound.

In the general formula (V) and the general formula (VI),
Q is an acyl group represented by the following general formula (VII),
In the general formula (I),
X is an acidic group represented by the following general formula (VIII),
In the acidic group introduction step, Q is preferably converted to X by reacting Q with cyanoacetic acid.

前記一般式（VII）および一般式（VIII）中、
Ｒ^１０は、水素原子、置換若しくは無置換のアルキル基、または置換若しくは無置換のアリール基であり、
前記一般式（VIII）中、
−ＣＯＯＨのＨは、例えば、前記一般式（２）と同じＭで置換してもよい。

In the general formula (VII) and general formula (VIII),
R ¹⁰ is a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group,
In the general formula (VIII),
For example, H in —COOH may be substituted with the same M as in the general formula (2).

<Dye for photoelectric conversion>
The photoelectric conversion dye of the present invention contains at least one of the pyrrole compound of the present invention, a tautomer or stereoisomer thereof, or a salt thereof. The pyrrole compound and the like are useful as a dye for photoelectric conversion having excellent photoelectric conversion characteristics.

<Photoelectric conversion element for photoelectrochemical cell>
FIG. 1 schematically shows a cross-sectional structure of an example of the photoelectric conversion element for a photoelectrochemical cell of the present invention. The photoelectric conversion element shown in FIG. 1 includes a semiconductor electrode 4 for a photoelectrochemical cell, a counter electrode 8, and an electrolyte layer (charge transport layer) 5 held between both electrodes. The semiconductor electrode 4 for photoelectrochemical cells includes a conductive substrate including a light transmissive substrate 3 and a transparent conductive layer 2, and a semiconductor layer 1. The counter electrode 8 includes a catalyst layer 6 and a substrate 7. The semiconductor layer 1 is adsorbed with the photoelectric conversion dye.

  When light is incident on the photoelectric conversion element for photoelectrochemical cell, the photoelectric conversion dye adsorbed on the semiconductor layer 1 is excited and emits electrons. The electrons move to the conduction band of the semiconductor, and further move to the transparent conductive layer 2 by diffusion. The electrons in the transparent conductive layer 2 move to the counter electrode 8 via an external circuit (not shown). The photoelectric conversion dye (oxidized dye) that has released the electrons receives (reduced) electrons from the electrolyte layer 5 and returns to the original state, so that the photoelectric conversion dye is regenerated. On the other hand, the electrons moved to the counter electrode give electrons to the electrolyte layer 5 and reduce the electrolyte, thereby functioning as a battery (for example, a dye-sensitized solar cell). Hereinafter, each component will be described by taking the photoelectric conversion element for a photoelectrochemical cell shown in FIG. 1 as an example.

<Conductive electrode for semi-photoelectrochemical cell>
The semiconductor electrode 4 for photoelectrochemical cells includes the conductive substrate including the light-transmitting substrate 3 and the transparent conductive layer 2 and the semiconductor layer 1 as described above. As shown in FIG. 1, a light transmissive substrate 3, a transparent conductive layer 2, and a semiconductor layer 1 are laminated in this order from the outside to the inside of the element. The semiconductor layer 1 is adsorbed with a dye for photoelectric conversion (not shown).

<Conductive substrate>
The conductive substrate constituting the semiconductor electrode 4 for photoelectrochemical cells may have a single-layer structure in which the substrate itself has conductivity, or a two-layer structure in which a conductive layer is formed on the substrate. Also good. The conductive substrate of the photoelectric conversion element for a photoelectrochemical cell shown in FIG. 1 has a two-layer structure in which a transparent conductive layer 2 is formed on a light transmissive substrate 3.

  Examples of the substrate used for the conductive substrate include a glass substrate, a plastic substrate, and a metal plate. Among them, a substrate having high light transmittance, for example, a transparent plastic substrate is particularly preferable. Examples of the material for the transparent plastic substrate include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polycycloolefin, and polyphenylene sulfide.

In addition, the conductive layer (for example, the transparent conductive layer 2) formed on the substrate (for example, the light transmissive substrate 3) is not particularly limited, but for example, indium tin oxide (Indium-Tin-Oxide: A transparent conductive layer made of a transparent material such as ITO, fluorine-doped tin oxide (FTO), indium-zinc oxide (IZO), tin oxide (SnO ₂ ), or the like is preferable. The conductive layer formed over the substrate can be formed into a film shape over the entire surface or a part of the surface of the substrate. The thickness of the conductive layer can be selected as appropriate, but is preferably about 0.02 μm to 10 μm. Such a conductive layer can be formed using a normal film formation technique.

  The conductive substrate in the present embodiment can be provided with a metal lead wire for the purpose of reducing the resistance of the conductive substrate. Examples of the material of the metal lead wire include metals such as aluminum, copper, gold, silver, platinum, and nickel. The metal lead wire can be produced by vapor deposition, sputtering, or the like. After a metal lead wire is formed on the substrate (for example, the light transmissive substrate 3), a conductive layer (for example, a transparent conductive layer 2 such as ITO or FTO) can be provided on the metal lead wire. Or. After providing a conductive layer (for example, transparent conductive layer 2) on a substrate (for example, light transmissive substrate 3), a metal lead wire may be formed on this conductive layer.

  In the following description of the embodiment, on the assumption that a conductive substrate having a two-layer structure in which a transparent conductive layer 2 is formed on a light-transmitting substrate 3 is used as the conductive substrate in the semiconductor electrode 4 for a photoelectrochemical cell, The operation principle of the photoelectrochemical cell (for example, dye-sensitized solar cell) according to the present invention will be described. However, the technical scope of the present invention is not limited to the illustrated embodiment.

<Semiconductor layer>
As a material constituting the semiconductor layer 1, a single semiconductor such as silicon or germanium, a compound semiconductor such as a metal chalcogenide, a semiconductor compound having a perovskite structure, or the like can be used.

  Metal chalcogenides include oxides such as titanium, tin, zinc, iron, tungsten, indium, zirconium, vanadium, niobium, tantalum, strontium, hafnium, cerium, lanthanum; cadmium, zinc, lead, silver, antimony, bismuth, etc. Sulfides; selenides such as cadmium and lead; tellurides of cadmium and the like. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium; gallium arsenide; copper-indium-selenide; copper-indium-sulfide. Examples of the semiconductor compound having a perovskite structure include commonly known semiconductor compounds such as barium titanate, strontium titanate, and potassium niobate. These semiconductor materials can be used alone or in combination of two or more.

  Among these semiconductor materials, from the viewpoint of conversion efficiency, stability, and safety, a semiconductor material containing titanium oxide or zinc oxide is preferable, and a semiconductor material containing titanium oxide is more preferable. Examples of titanium oxide include various types of titanium oxide such as anatase type titanium oxide, rutile type titanium oxide, amorphous titanium oxide, metatitanic acid, orthotitanic acid, and a titanium oxide-containing complex can be used. . Among these, anatase type titanium oxide is preferable from the viewpoint of further improving the stability of photoelectric conversion.

  Examples of the form of the semiconductor layer include a porous semiconductor layer obtained by sintering semiconductor fine particles, a thin film semiconductor layer obtained by a sol-gel method, a sputtering method, a spray pyrolysis method, and the like. Moreover, it is good also as a semiconductor layer which consists of a fibrous semiconductor layer or an acicular crystal | crystallization. The form of these semiconductor layers can be appropriately selected according to the purpose of use of the photoelectric conversion element. Among these, a semiconductor layer having a large specific surface area such as a porous semiconductor layer and a needle-like semiconductor layer is preferable from the viewpoint of the amount of dye adsorbed. Furthermore, a porous semiconductor layer formed from semiconductor fine particles is preferable from the viewpoint that the utilization factor of incident light and the like can be adjusted by the particle size of the semiconductor fine particles. Further, the semiconductor layer may be a single layer or a multilayer. By forming a multilayer, a sufficiently thick semiconductor layer can be more easily formed. Moreover, when the porous semiconductor layer formed from semiconductor fine particles is a multilayer, you may form several semiconductor layers from which the average particle diameter of semiconductor fine particles differs. For example, the average particle diameter of the semiconductor fine particles of the semiconductor layer closer to the light incident side (first semiconductor layer) may be smaller than that of the semiconductor layer farther from the light incident side (second semiconductor layer). In this way, the first semiconductor layer absorbs a lot of light, and the light that has passed through the first semiconductor layer is efficiently scattered by the second semiconductor layer and returned to the first semiconductor layer, and the returned light is returned to the first semiconductor layer. By making it absorb with 1 semiconductor layer, the whole optical absorptance can be improved further.

Although the film thickness of a semiconductor layer is not specifically limited, From viewpoints, such as permeability | transmittance and conversion efficiency, it can be 0.5 micrometer or more and 45 micrometers or less, for example. More preferably, they are 1 micrometer or more and 30 micrometers or less. The specific surface area of the semiconductor layer can be set to, for example, 10 m ² / g or more and 200 m ² / g or less from the viewpoint of adsorbing a large amount of dye.

  Further, in the case where the dye is adsorbed on the porous semiconductor layer, the porosity of the porous semiconductor layer is, for example, 40% from the viewpoint that ions in the electrolyte are further sufficiently diffused and charge transport is performed. It is preferable to be 80% or less. Here, the porosity is a percentage of the volume of the semiconductor layer occupied by the pores in the semiconductor layer.

<Method for forming semiconductor layer>
Next, a method for forming the semiconductor layer 1 will be described by taking the case of a porous semiconductor layer as an example. The porous semiconductor layer can be formed, for example, as follows. First, a suspension is prepared by adding semiconductor fine particles together with an organic compound such as a resin and a dispersant to a dispersion medium such as an organic solvent or water. And this suspension is apply | coated on a conductive substrate (transparent conductive layer 2 in FIG. 1), a semiconductor layer is obtained by drying and baking this. When an organic compound is added to the dispersion medium together with the semiconductor fine particles, the organic compound is combusted at the time of firing, so that a sufficient gap (void) can be secured in the porous semiconductor layer. Moreover, the porosity can be changed by controlling the molecular weight and the addition amount of the organic compound combusted at the time of baking.

  The organic compound is not particularly limited as long as it can be dissolved in a suspension and burned and removed when fired. For example, polyethylene glycol, cellulose ester resin, cellulose ether resin, epoxy resin, urethane resin, phenol resin, polycarbonate resin, polyarylate resin, polyvinyl butyral resin, polyester resin, polyvinyl formal resin, silicone resin, styrene, Examples thereof include polymers and copolymers of vinyl compounds such as vinyl acetate, acrylic acid esters, and methacrylic acid esters. The type and amount of the organic compound can be appropriately selected according to the type and state of the fine particles used, the composition ratio of the suspension, the total weight, and the like. The ratio of the semiconductor fine particles is preferably 10% by mass or more and 40% by mass or less with respect to the total weight of the entire suspension. When the ratio of the semiconductor fine particles is 10% by mass or more based on the total weight of the entire suspension, the strength of the produced film can be further sufficiently increased. Moreover, if the ratio of the semiconductor fine particles is 40% by mass or less with respect to the total weight of the whole suspension, a porous semiconductor layer having a large porosity can be obtained more stably.

  As the semiconductor fine particles, single or plural compound semiconductor particles having an appropriate average particle diameter, for example, an average particle diameter of about 1 nm to about 500 nm, for example, compound semiconductor particles such as metal chalcogenide are used. it can. Among these, from the viewpoint of increasing the specific surface area, those having an average particle diameter of about 1 nm to 50 nm are desirable. In order to increase the utilization factor of incident light, semiconductor particles having a relatively large average particle diameter of about 200 nm to 400 nm may be added.

  Examples of the method for producing the semiconductor fine particles include a sol-gel method such as a hydrothermal synthesis method, a sulfuric acid method, and a chlorine method. The method is not limited as long as the method can produce the desired fine particles. Is preferably synthesized by a hydrothermal synthesis method.

  Examples of the dispersion medium used in the suspension include glyme solvents such as ethylene glycol monomethyl ether; alcohols such as isopropyl alcohol; mixed solvents such as isopropyl alcohol / toluene; water and the like.

  The suspension can be applied by a usual application method such as a doctor blade method, a squeegee method, a spin coating method, or a screen printing method. The conditions of drying and baking of the coating film performed after application of the suspension are, for example, about 10 seconds to 12 hours in the range of about 50 ° C. to 800 ° C. in the air or in an inert gas atmosphere. it can. This drying and baking may be performed once or a plurality of times at a single temperature, or may be performed a plurality of times by changing the temperature.

  Other types of semiconductor layers other than the porous semiconductor layer can be formed using a normal method for forming a semiconductor layer used in a photoelectric conversion element for a photoelectrochemical cell.

<Adsorption method of photoelectric conversion dye>
The photoelectric conversion dye is as described above. As a method for adsorbing the dye on the semiconductor layer 1, for example, a method of immersing a semiconductor substrate (that is, a conductive substrate including the semiconductor layer 1) in a solution in which the dye is dissolved, or a solution of the dye in the semiconductor layer The method of apply | coating to 1 and making it adsorb | suck.

  Solvents for this dye solution include nitrile solvents such as acetonitrile, propionitrile, methoxyacetonitrile; alcohol solvents such as methanol, ethanol, isopropyl alcohol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; acetic acid Ester solvents such as ethyl and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl-2-pyrrolidone; dichloromethane, chloroform, And halogen solvents such as dichloroethane, trichloroethane, and chlorobenzene; hydrocarbon solvents such as toluene, xylene, and cyclohexane; and water. These may be used alone or in combination of two or more.

  When the method of immersing the semiconductor substrate in the dye solution is employed, the solution may be stirred, heated to reflux, or ultrasonic waves may be applied when the semiconductor substrate is immersed in the dye solution. it can.

  After the dye adsorption treatment, it is desirable to wash with a solvent such as alcohol in order to remove the dye remaining without being adsorbed.

The amount of the dye supported can be set, for example, within a range of 1 × 10 ⁻¹⁰ mol / cm ^{2 to} 1 × 10 ⁻⁴ mol / cm ² , and is 1 × 10 ⁻⁹ mol / cm ^{2 to} 9.0 × 10. A range of ⁻⁶ mol / cm ² or less is preferred. Within this range, the effect of improving the photoelectric conversion efficiency can be obtained economically and sufficiently.

  Further, in order to make the wavelength range capable of photoelectric conversion as wide as possible and increase the conversion efficiency, two or more types of photoelectric conversion dyes may be used in combination, in which case the absorption wavelength range and intensity of the dye are taken into consideration. Thus, it is preferable to appropriately select the type and ratio of the pigment. In addition, an additive may be used in combination when adsorbing the dye in order to suppress a decrease in conversion efficiency due to the association between the dyes. Examples of such additives include steroidal compounds having a carboxyl group (for example, deoxycholic acid, cholic acid, chenodeoxycholic acid, etc.).

<Counter electrode>
The counter electrode 8 in this example has a catalyst layer 6 on a substrate 7. In this photoelectric conversion element for a photoelectrochemical cell, holes generated from the dye adsorbed on the semiconductor layer 1 due to the incidence of light are carried to the counter electrode 8 through the electrolyte layer 5. There is no limit to the material as long as it can perform the function of effectively eliminating the pair.

  The catalyst layer 6 can be formed as a metal vapor deposition film on the substrate 7, for example, by vapor deposition or the like. The catalyst layer 6 may be, for example, a Pt layer formed on the substrate 7. Further, the catalyst layer 6 may contain a nanocarbon material. For example, the catalyst layer 6 may be formed by sintering a paste containing carbon nanotubes, carbon nanohorns, or carbon fibers on the porous insulating film. Nanocarbon materials have a large specific surface area and can improve the probability of annihilation of electrons and holes.

  Examples of the substrate 7 include a transparent substrate such as glass and a polymer film, and a metal plate (foil). When the light-transmissive counter electrode 8 is manufactured, glass with a transparent conductive film is selected as the substrate 7, and platinum or carbon (for example, a nanocarbon material) is catalyzed on the glass substrate using a vapor deposition method or a sputtering method. The layer 6 can be formed.

<Electrolyte layer (charge transport layer)>
The electrolyte layer (charge transport layer) 5 has a function of transporting holes generated from the dye adsorbed on the semiconductor layer 1 due to incidence of light to the counter electrode 8. The electrolyte layer 5 contains a charge transport material. The electrolyte layer 5 includes an electrolytic solution in which a redox couple is dissolved in an organic solvent, a gel electrolyte in which a liquid in which the redox couple is dissolved in an organic solvent is impregnated in a polymer matrix, a molten salt containing the redox couple, a solid electrolyte, an organic A hole transport material or the like can be used.

The electrolyte layer can be composed of an electrolyte, a solvent, and an additive. As the electrolyte, LiI, NaI, KI, CsI , CaI 2 , etc. of the metal iodides, tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide iodide and _{I 2,} such as iodine salts of quaternary ammonium compounds such as id A combination of a bromide such as a bromide of a quaternary ammonium compound such as a metal bromide such as LiBr, NaBr, KBr, CsBr or CaBr ₂ or a tetraalkylammonium bromide or pyridinium bromide; and a Br ₂ salt; Metal complexes such as ferricyanate and ferrocene-ferricinium ions; sulfur compounds such as sodium polysulfide and alkylthiol-alkyl disulfides; viologen dyes; hydroquinone-quinone and the like. Among these, a combination of LiI and pyridinium iodide, or a combination of imidazolium iodide and I ₂ is preferable. Moreover, said electrolyte may be used independently or may be used in mixture of 2 or more types. In addition, a molten salt that is in a molten state at room temperature can be used as the electrolyte. In this case, a solvent need not be used.

  Examples of the solvent include carbonate solvents such as ethylene carbonate, diethyl carbonate, dimethyl carbonate, and propylene carbonate; amide solvents such as N-methyl-2-pyrrolidone and N, N-dimethylformamide; methoxypropionitrile, pro Nitrile solvents such as pionitrile, methoxyacetonitrile, acetonitrile; lactone solvents such as γ-butyrolactone and valerolactone; ether solvents such as tetrahydrofuran, dioxane, diethyl ether, ethylene glycol dialkyl ether; methanol, ethanol, isopropyl alcohol, etc. Alcohol solvents; aprotic polar solvents such as dimethyl sulfoxide, sulfolane; 2-methyl-3-oxazolidinone, 2-methyl-1,3-dioxola Heterocyclic compounds, and the like and the like. These solvents may be used alone or in combination of two or more.

  A basic compound may be added to the electrolyte layer in order to suppress dark current. Although it does not specifically limit as a kind of basic compound, t-butyl pyridine, 2-picoline (2-methylpyridine), 2, 6- lutidine, etc. are mentioned. The addition concentration in the case of adding a basic compound can be, for example, about 0.05 mol / L or more and 2 mol / L or less.

  A solid electrolyte can also be used as the electrolyte layer. As this solid electrolyte, a gel electrolyte or a completely solid electrolyte can be used. As gel electrolyte, what added electrolyte or normal temperature molten salt in the gelatinizer can be used. As a gelation method, gelation can be performed by a technique such as addition of a polymer or an oil gelling agent, polymerization of coexisting polyfunctional monomers, or a polymer crosslinking reaction. Examples of the polymer for gelation by adding a polymer include polyacrylonitrile and polyvinylidene fluoride. Oil gelling agents include dibenzylden-D-sorbitol, cholesterol derivatives, amino acid derivatives, alkylamide derivatives of trans- (1R, 2R) -1,2-cyclohexanediamine, alkylurea derivatives, N-octyl-D-gluconamide benzoate Double-headed amino acid derivatives, quaternary ammonium salt derivatives, and the like.

  When gelation is performed by polymerization of a polyfunctional monomer, the monomer used is preferably a compound having two or more ethylenically unsaturated groups, such as divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, Examples include diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate, and trimethylolpropane triacrylate. In the gelation, a monofunctional monomer may be included in addition to the polyfunctional monomer. Monofunctional monomers include esters derived from acrylic acid and α-alkyl acrylic acids such as acrylamide, N-isopropylacrylamide, methyl acrylate and hydroxyethyl acrylate; amides; dimethyl maleate, diethyl fumarate, dibutyl maleate Esters derived from maleic acid and fumaric acid such as: Dienes such as butadiene, isoprene and cyclopentadiene; Aromatic vinyl compounds such as styrene, p-chlorostyrene and sodium styrenesulfonate; Vinyl esters such as vinyl acetate Nitriles such as acrylonitrile and methacrylonitrile; vinyl compounds having a nitrogen-containing heterocycle such as vinyl carbazole; vinyl compounds having a quaternary ammonium salt; other N-vinylformamide and vinyl sulfone , Vinylidene fluoride, vinyl alkyl ethers, N- phenylmaleimide, and the like. 0.5 mass% or more and 70 mass% or less are preferable, and, as for the polyfunctional monomer which occupies for the monomer whole quantity, 1.0 mass% or more and 50 mass% or less are more preferable.

  Polymerization of the monomer for gelation can be performed by a radical polymerization method or the like. This radical polymerization can be carried out by heating, light, ultraviolet light or electron beam, or electrochemically. Examples of the polymerization initiator used when forming a crosslinked polymer by heating include azo initiators such as 2,2′-azobis (isobutyronitrile) and 2,2′-azobis (dimethylvaleronitrile), Examples thereof include peroxide initiators such as benzoyl peroxide. The addition amount of the polymerization initiator is preferably 0.01% by mass or more and 15% by mass or less, and more preferably 0.05% by mass or more and 10% by mass or less with respect to the total amount of monomers.

  When gelation is performed by a crosslinking reaction of a polymer, it is desirable to use a polymer having a reactive group necessary for the crosslinking reaction and a crosslinking agent in combination. Preferred crosslinkable reactive groups are nitrogen-containing heterocycles such as pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring, and preferred crosslinkers are alkyl halides, halogenated alkyls. Bifunctional or higher functional compounds capable of electrophilic substitution reaction with nitrogen atoms such as aralkyl, sulfonic acid ester, acid anhydride, acid chloride, isocyanate and the like can be mentioned.

  As the complete solid electrolyte, for example, a mixture of an electrolyte and an ion conductive polymer compound can be used. Examples of the ion conductive polymer compound include polar polymer compounds such as polyethers, polyesters, polyamines, and polysulfides.

  As the charge transport material, for example, an inorganic hole transport material such as copper iodide or copper thiocyanide can be used. The inorganic hole transport material can be introduced into the electrode by a method such as a casting method, a coating method, a spin coating method, a dipping method, or electrolytic plating.

  In the photoelectric conversion element for a photoelectrochemical cell of this example, an organic hole transport material can also be used as the charge transport material. Examples of the organic hole transport material include 2,2 ′, 7,7′-tetrakis (N, N-di-p-methoxyphenylamine) -9,9′-spirobifluorene (for example, Adv. Mater. 2005, 17, 813), aromatics such as N, N′-diphenyl-N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine Diamines (for example, compounds described in US Pat. No. 4,764,625), triphenylamine derivatives (for example, compounds described in JP-A-4-129271), stilbene derivatives (for example, JP-A-2- Compounds described in Japanese Patent No. 51162), hydrazone derivatives (for example, compounds described in JP-A-2-226160), and the like. The organic hole transport material can be introduced into the electrode by a method such as a vacuum deposition method, a cast method, a spin coating method, a dipping method, or an electrolytic polymerization method.

  The electrolyte layer 5 can be produced, for example, by the following two methods. One is a method in which the counter electrode 8 is first bonded onto the semiconductor layer 1 on which the photoelectric conversion dye is adsorbed, and the liquid electrolyte layer 5 is introduced into the gap. The other is a method of forming the electrolyte layer 5 directly on the semiconductor layer 1. In the latter case, after the electrolyte layer 5 is formed, the counter electrode 8 is formed thereon.

  A photoelectrochemical cell can be provided by using the photoelectric conversion element for a photoelectrochemical cell described above. This photovoltaic chemical cell can be suitably used as a solar cell (for example, a dye-sensitized solar cell).

Hereinafter, the present invention will be described in more detail with reference to embodiments. Each embodiment illustrated below is an example of the best embodiment of the present invention, but the technical scope of the present invention is not limited to the form shown in this embodiment (first embodiment).
<Synthesis of pyrrole compound PY-1>
According to the following reaction formula, pyrrole compound PY-1 was synthesized as follows.

１，２−ジベンゾイルエタン５．９２ｇとｐ−オクチルアニリン６．６３ｇをトルエン６０ｍＬに溶解し、そこに酢酸６ｍＬを加え、１２時間加熱還流させた。放冷後、析出した結晶をろ別し、トルエンから再結晶することで、Ａ１を７．８１ｇ得た（収率５９％）。

1.92 g of 1,2-dibenzoylethane and 6.63 g of p-octylaniline were dissolved in 60 mL of toluene, 6 mL of acetic acid was added thereto, and the mixture was heated to reflux for 12 hours. After allowing to cool, the precipitated crystals were separated by filtration and recrystallized from toluene to obtain 7.81 g of A1 (yield 59%).

  Next, 10 g of A1 was dissolved in 260 mL of chloroform, and 4.46 g of N-bromosuccinimide was added and allowed to react for 4 hours under ice cooling. The reaction solution was concentrated under reduced pressure, and 150 mL of methanol was added to the residue, followed by heating, stirring and washing twice. Further, 8.65 g of A2 was obtained by recrystallization from ethyl acetate (yield 72%).

  Next, 2 g of A2 was dissolved in 40 mL of dry tetrahydrofuran (THF) and cooled to -78 ° C. Then, 3.1 mL of a 1.6 mol / L hexane solution of n-butyllithium was added dropwise under an argon atmosphere. After stirring at −78 ° C. for 30 minutes, 0.56 g of zinc chloride was added, and the mixture was further stirred for 1 hour. Thereafter, the temperature was returned to room temperature, and 1.011 g of 5-bromo-2,2'-bithiophene-5'-carboxaldehyde and 0.143 g of tetrakis (triphenylphosphine) palladium were added thereto, followed by stirring at room temperature for 3 hours. 200 mL of ethyl acetate was added to the reaction mixture, washed with 3% aqueous sodium carbonate solution and aqueous NaCl solution, and dried over magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was separated and purified on a silica gel column (developing solvent: hexane / ethyl acetate (volume mixing ratio: 2/1) mixed solvent) to obtain 0.285 g of compound A3 (yield) 12%).

  Next, 0.14 g of A3 was dissolved in 10 mL of acetonitrile, 0.031 g of cyanoacetic acid and 0.041 g of piperidine were added thereto, and the mixture was heated to reflux for 2 hours. After standing to cool, it was added dropwise to 300 mL of water containing 0.5 mL of hydrochloric acid. The precipitated crystals were separated by filtration, washed with water, dissolved in a small amount of THF, and reprecipitated in hexane to obtain 0.08 g of the desired pyrrole derivative PY-1 (yield 51%). .

The measurement result of ¹ H-NMR (dichloromethane-d2) of the obtained pyrrole compound PY-1 was as follows: δ was 8.28 (1H, s), 7.68 (1H, d), 7.14-7.31 (6H, m), 6.99 (2H, d), 6.91 (2H, d), 6.78 (1H, d), 6.73 (1H, d), 2 .53 (2H, t), 1.50-1.55 (2H, m), 1.16-1.35 (10H, m), 0.88 (3H, t)
Moreover, the absorption spectrum in acetonitrile of the obtained pyrrole type compound PY-1 (dye) is shown in FIG. Λ _max of this pyrrole compound PY-1 was 489 nm.

(Second embodiment)
<Production of photoelectric conversion element for photoelectrochemical cell>
A photoelectric conversion element for a photoelectrochemical cell was produced as follows.

(A) Production of Photoelectrochemical Battery Semiconductor Electrode and Counter Electrode First, a photoelectrochemical battery semiconductor electrode was produced in the following order.

A glass with FTO (10 Ωcm ² ) having a size of 15 mm × 15 mm and a thickness of 1.1 mm was prepared as a conductive substrate (light transmissive substrate with a transparent conductive layer).

  A titanium oxide paste (semiconductor layer material) was prepared as follows. Commercially available titanium oxide powder (trade name: P25, manufactured by Nippon Aerosil Co., Ltd., average primary particle size: 21 nm) 5 g, 15 vol% acetic acid aqueous solution 20 mL, surfactant 0.1 mL (trade name: Triton (registered trademark) X- 100, manufactured by Sigma-Aldrich Co., Ltd.) and 0.3 g of polyethylene glycol (molecular weight 20000) (manufactured by Wako Pure Chemical Industries, Ltd., product code: 168-11285) were mixed, and this mixture was stirred for about 1 hour with a stirring mixer, and oxidized. A titanium paste was obtained.

  Next, this titanium oxide paste was applied on a glass with FTO by a doctor blade method so that the film thickness was about 50 μm (application area: 10 mm × 10 mm). Thereafter, the glass with FTO coated with the titanium oxide paste was put in an electric furnace, baked at 450 ° C. for about 30 minutes in an air atmosphere, and naturally cooled to obtain a porous titanium oxide film on the glass with FTO. .

  Further, a light scattering layer was formed on the titanium oxide film as follows. A titanium oxide paste having an average particle diameter of 400 nm (trade name: PST-400C, manufactured by JGC Catalysts & Chemicals Co., Ltd.) was applied to the above-described titanium oxide film with a thickness of 20 μm by a screen printing method. Then, the light-scattering layer on the titanium oxide film was obtained by baking for about 30 minutes at 450 degreeC in air | atmosphere, and allowing it to cool naturally. As described above, a semiconductor electrode before the dye was adsorbed was obtained.

  On the other hand, a platinum layer having an average film thickness of 1 μm was deposited as a catalyst layer on a soda lime glass plate (thickness 1.1 mm) by a vacuum deposition method to obtain a counter electrode.

(B) Dye adsorption Next, a dye for photoelectric conversion was adsorbed on the surface of the semiconductor layer composed of the above-described titanium oxide thin film. For adsorption of the photoelectric conversion dye, a solution in which the pyrrole compound PY-1 of Example 1 was dissolved in acetonitrile at a concentration of about 2 × 10 ⁻⁴ M was used. The above-mentioned semiconductor electrode was immersed in this dye solution and stored overnight. Thereafter, the semiconductor electrode was taken out from the dye solution, rinsed with acetonitrile to remove excess dye, and dried in air to obtain a semiconductor electrode on which the photoelectric conversion dye was adsorbed.

(C) Cell assembly The semiconductor electrode for photoelectrochemical cell after the above-mentioned dye conversion treatment for photoelectric conversion and the above-mentioned counter electrode are arranged so that the semiconductor layer and the catalyst layer face each other to form a cell before electrolyte injection did. Next, the circumference | surroundings of the cell part were thermocompression-bonded with the thermosetting resin film which cut | disconnected the electrolyte so that it could osmose | permeate a clearance gap.

(D) Injection of electrolyte layer An iodine-based electrolyte was injected into the above-described cell from where the above-mentioned cut was made. The iodine-based electrolyte uses acetonitrile as a solvent, the concentration of iodine (I ₂ ) is 0.5 mol / L, the concentration of lithium iodide is 0.1 mol / L, and the concentration of 4-tert-butylpyridine is 0.5 mol / L. A solution having a concentration of L, 1,2-dimethyl-3-propylimidazolium iodide of 0.6 mol / L was used.

(E) Photocurrent measurement The photoelectric conversion element for a photoelectrochemical cell produced as described above is irradiated with light having an intensity of 100 mW / cm ² under AM1.5 conditions with a solar simulator, and the generated electricity is converted into a current. It measured with the voltage measuring device and evaluated the photoelectric conversion characteristic. As a result, the photoelectric conversion efficiency was 2.7%.

  While the present invention has been described with reference to the embodiments (and examples), the present invention is not limited to the above embodiments (and examples). Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2010-278660 for which it applied on December 14, 2010, and takes in those the indications of all here.

  As described above, the pyrrole compound of the present invention, a tautomer or stereoisomer thereof, or a salt thereof is useful for a photoelectric conversion dye. The photoelectric conversion dye containing the pyrrole compound of the present invention is excellent in photoelectric conversion characteristics. In addition, since no noble metal such as ruthenium is essential, the problem of resource limitation is solved, and a solar cell (for example, a dye-sensitized solar cell) can be supplied at a lower cost. Therefore, it is possible to use solar cells (for example, dye-sensitized solar cells) for a wide range of applications. The use of the pyrrole compound of the present invention is not limited to solar cells (for example, dye-sensitized solar cells), and can be used in various fields.

A part or all of the above-described embodiment can be described as in the following supplementary notes, but is not limited thereto.
(Appendix 1)
A pyrrole compound represented by the following general formula (1), a tautomer or stereoisomer thereof, or a salt thereof.

前記一般式（１）中、
Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表し、
Ｘは、酸性基を有する基を表し、
Ｚは、チオフェン環、フラン環およびピロール環からなる群から選択される少なくとも一種の複素環を有する連結基を表す。

In the general formula (1),
R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group,
X represents a group having an acidic group,
Z represents a linking group having at least one heterocyclic ring selected from the group consisting of a thiophene ring, a furan ring and a pyrrole ring.

In addition, it is preferable that the pyrrole ring utilized for the structure of Z has a structure of 1H-pyrrole among three isomers of 1H-pyrrole, 2H-pyrrole, and 3H-pyrrole.
(Appendix 2)
In R ^{1 to} R ⁴ ,
The alkyl group has 1 to 12 carbon atoms,
The pyrrole compound according to Supplementary Note 1, the tautomer or stereoisomer thereof, or a salt thereof, wherein the aryl group has 5 to 24 carbon atoms.
(Appendix 3)
The pyrrole compound, its tautomer or stereoisomer, or a salt thereof according to appendix 1 or appendix 2, wherein X is an organic group having an acidic group.
(Appendix 4)
4. The pyrrole compound according to appendix 3, a tautomer or stereoisomer thereof, or a salt thereof, wherein X is a group in which an acidic group is bonded to a group that can be conjugated with Z.
(Appendix 5)
The pyrrole compound, its tautomer or stereoisomer, or a salt thereof according to appendix 4, wherein the group capable of conjugating with Z is a group having a carbon-carbon double bond.
(Appendix 6)
X is a group represented by any one of the following formulas (Xa) to (Xm), the pyrrole compound according to any one of appendix 1 to appendix 5, a tautomer or stereoisomer thereof Bodies, or their salts.

前記式（Ｘａ）〜（Ｘｍ）中、
Ｍは、水素原子または塩形成性陽イオンを表し、
Ｂ⁻は、水酸化物イオンまたは塩形成性陰イオンを表す。
（付記７）
Ｘが、下記式（Ｘ１）〜（Ｘ１６）のいずれかで表される基である
ことを特徴とする付記１〜付記５のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。

In the formulas (Xa) to (Xm),
M represents a hydrogen atom or a salt-forming cation,
B ⁻ represents a hydroxide ion or a salt-forming anion.
(Appendix 7)
X is a group represented by any one of the following formulas (X1) to (X16), the pyrrole compound according to any one of appendix 1 to appendix 5, a tautomer or stereoisomer thereof Bodies, or their salts.

（付記８）
Ｘが、下記一般式（２）で表される基である
ことを特徴とする付記１〜付記５のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。

(Appendix 8)
X is a group represented by the following general formula (2), the pyrrole compound according to any one of appendix 1 to appendix 5, its tautomer or stereoisomer, or a salt thereof .

前記一般式（２）中、Ｍは、水素原子または塩形成性陽イオンを表す。
（付記９）
Ｚが、下記一般式（３）で表される構造を含む原子団である
ことを特徴とする付記１〜付記８のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。

In the general formula (2), M represents a hydrogen atom or a salt-forming cation.
(Appendix 9)
Z is an atomic group including a structure represented by the following general formula (3), the pyrrole compound according to any one of appendix 1 to appendix 8, a tautomer or stereoisomer thereof, Or their salts.

前記一般式（３）中、
Ｒ^５、Ｒ^６は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換の直鎖若しくは分枝アルコキシ基を表し、
Ｒ^５、Ｒ^６は互いに連結されて環を形成してもよく、
Ｙは、酸素原子、硫黄原子またはＮＲａを表し、
Ｒａは、水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表す。
（付記１０）
下記一般式（４）で表される
ことを特徴とする付記１〜付記９のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。

In the general formula (3),
R ⁵ and R ⁶ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted linear or branched alkoxy group,
R ⁵ and R ⁶ may be connected to each other to form a ring,
Y represents an oxygen atom, a sulfur atom or NRa;
Ra represents a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group.
(Appendix 10)
The pyrrole compound according to any one of appendix 1 to appendix 9, which is represented by the following general formula (4), a tautomer or stereoisomer thereof, or a salt thereof.

前記一般式（４）中、
Ｒ^１〜Ｒ^４は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表し、
Ｍは、水素原子または塩形成性陽イオンを表し、
Ｚは、下記一般式（３）で表される構造を含む連結基を表す。

In the general formula (4),
R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group,
M represents a hydrogen atom or a salt-forming cation,
Z represents a linking group including a structure represented by the following general formula (3).

前記一般式（３）中、
Ｒ^５、Ｒ^６は、それぞれ独立に水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換の直鎖若しくは分枝アルコキシ基を表し、
Ｒ^５、Ｒ^６は互いに連結されて環を形成してもよく、
Ｙは、酸素原子、硫黄原子、またはＮＲａを表し、
Ｒａは、水素原子、置換若しくは無置換の直鎖若しくは分枝アルキル基、または置換若しくは無置換のアリール基を表す。
（付記１１）
Ｒ^５およびＲ^６において、
前記アルキル基の炭素数が１〜１２であり、
前記アリール基の炭素数が５〜２４である
ことを特徴とする付記１０に記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。
（付記１２）
Ｚが、下記式（Ｚ１）〜（Ｚ２０）のいずれかで表される
ことを特徴とする付記１〜付記１１のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。

In the general formula (3),
R ⁵ and R ⁶ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted linear or branched alkoxy group,
R ⁵ and R ⁶ may be connected to each other to form a ring,
Y represents an oxygen atom, a sulfur atom, or NRa;
Ra represents a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group.
(Appendix 11)
In R ⁵ and R ⁶
The alkyl group has 1 to 12 carbon atoms,
The pyrrole compound according to appendix 10, the tautomer or stereoisomer thereof, or a salt thereof, wherein the aryl group has 5 to 24 carbon atoms.
(Appendix 12)
Z is represented by any one of the following formulas (Z1) to (Z20), the pyrrole compound according to any one of appendix 1 to appendix 11, a tautomer or stereoisomer thereof, or Their salt.

（付記１３）
下記式ＰＹ−１で表される
ことを特徴とする付記１に記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩。

(Appendix 13)
The pyrrole compound according to supplementary note 1, represented by the following formula PY-1, a tautomer or stereoisomer thereof, or a salt thereof.

（付記１４）
付記１〜付記１３のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩の少なくとも一種を含む
ことを特徴とする光電変換用色素。
（付記１５）
付記１４に記載の光電変換用色素を含む半導体層を有する
ことを特徴とする光電気化学電池用半導体電極。
（付記１６）
前記半導体層が、単体半導体、化合物半導体、金属カルコゲニド、およびペロブスカイト構造を有する半導体化合物からなる群から選択される少なくとも一つである
ことを特徴とする
付記１５に記載の光電気化学電池用半導体電極。
（付記１７）
前記単体半導体が、シリコンまたはゲルマニウムの少なくとも一方である
ことを特徴とする付記１６に記載の光電気化学電池用半導体電極。
（付記１８）
前記金属カルコゲニドが、
チタン、スズ、亜鉛、鉄、タングステン、インジウム、ジルコニウム、バナジウム、ニオブ、タンタル、ストロンチウム、ハフニウム、セリウム、またはランタンの酸化物；
カドミウム、亜鉛、鉛、銀、アンチモン、またはビスマスの硫化物；
カドミウム、鉛のセレン化物；および
カドミウムのテルル化物からなる群から選択される少なくとも一つである
ことを特徴とする付記１６または付記１７に記載の光電気化学電池用半導体電極。
（付記１９）
前記化合物半導体が、
付記１８に記載の金属カルコゲニド；
亜鉛、ガリウム、インジウム、またはカドミウムのリン化物；
ガリウム砒素；
銅−インジウム−セレン化物；および
銅−インジウム−硫化物からなる群から選択される少なくとも一つである
ことを特徴とする付記１６〜付記１８のいずれかに記載の光電気化学電池用半導体電極。
（付記２０）
前記ペロブスカイト構造を有する化合物が、
チタン酸バリウム、チタン酸ストロンチウム、およびニオブ酸カリウムからなる群から選択される少なくとも一つである
ことを特徴とする付記１６〜付記１９のいずれかに記載の光電気化学電池用半導体電極。
（付記２１）
前記半導体層が、酸化チタンまたは酸化亜鉛を含む
ことを特徴とする付記１５〜付記２０のいずれかに記載の光電気化学電池用半導体電極。
（付記２２）
付記１５〜付記２１のいずれかに記載の光電気化学電池用半導体電極を有することを特徴とする光電気化学電池用光電変換素子。
（付記２３）
さらに、前記光電気化学電池用半導体電極に対向する対電極を有しており、
前記光電気化学電池用半導体電極と前記対電極との間に電荷輸送材料を含んでいる
ことを特徴とする付記２２に記載の光電気化学電池用光電変換素子。
（付記２４）
付記２２または付記２３に記載の光電気化学電池用光電変換素子を有することを特徴とする光電気化学電池。
（付記２５）
下記一般式（Ｉ）で表される化合物と、下記一般式（II）で表される化合物とを反応させてピロール環を形成し、下記一般式（III）で表されるピロール誘導体を製造するピロール環形成工程；
下記一般式（III）で表されるピロール誘導体をハロゲン化して、下記一般式（IV）で表されるハロゲン化ピロール誘導体を製造するハロゲン化工程；
下記一般式（IV）で表されるハロゲン化ピロール誘導体と下記一般式（Ｖ）で表されるハロゲン化物とをカップリング反応させて、下記一般式（VI）で表される化合物を製造するカップリング工程；および、
下記一般式（VI）中のＱを変換して酸性基Ｘを導入し、前記一般式（１）で表される化合物を製造する酸性基導入工程を含む
ことを特徴とする付記１〜付記１３のいずれかに記載のピロール系化合物、その互変異性体若しくは立体異性体、またはそれらの塩の製造方法。

(Appendix 14)
A pyrrole compound according to any one of appendix 1 to appendix 13, a tautomer or stereoisomer thereof, or a salt thereof, wherein the dye for photoelectric conversion is characterized.
(Appendix 15)
A semiconductor electrode for a photoelectrochemical cell, comprising a semiconductor layer containing the photoelectric conversion dye according to appendix 14.
(Appendix 16)
16. The semiconductor electrode for a photoelectrochemical cell according to appendix 15, wherein the semiconductor layer is at least one selected from the group consisting of a single semiconductor, a compound semiconductor, a metal chalcogenide, and a semiconductor compound having a perovskite structure. .
(Appendix 17)
The semiconductor electrode for photoelectrochemical cells according to appendix 16, wherein the single semiconductor is at least one of silicon and germanium.
(Appendix 18)
The metal chalcogenide is
Oxides of titanium, tin, zinc, iron, tungsten, indium, zirconium, vanadium, niobium, tantalum, strontium, hafnium, cerium, or lanthanum;
Cadmium, zinc, lead, silver, antimony, or bismuth sulfide;
18. The semiconductor electrode for a photoelectrochemical cell according to appendix 16 or appendix 17, wherein the semiconductor electrode is at least one selected from the group consisting of cadmium, lead selenide; and cadmium telluride.
(Appendix 19)
The compound semiconductor is
Metal chalcogenide according to appendix 18,
Zinc, gallium, indium, or cadmium phosphide;
Gallium arsenide;
The semiconductor electrode for a photoelectrochemical cell according to any one of appendix 16 to appendix 18, wherein the semiconductor electrode is at least one selected from the group consisting of copper-indium-selenide; and copper-indium-sulfide.
(Appendix 20)
The compound having the perovskite structure is
20. The semiconductor electrode for photoelectrochemical cells according to any one of supplementary notes 16 to 19, wherein the semiconductor electrode is at least one selected from the group consisting of barium titanate, strontium titanate, and potassium niobate.
(Appendix 21)
21. The semiconductor electrode for a photoelectrochemical cell according to any one of appendix 15 to appendix 20, wherein the semiconductor layer contains titanium oxide or zinc oxide.
(Appendix 22)
A photoelectric conversion element for a photoelectrochemical cell, comprising the semiconductor electrode for a photoelectrochemical cell according to any one of appendix 15 to appendix 21.
(Appendix 23)
Furthermore, it has a counter electrode facing the semiconductor electrode for photoelectrochemical cells,
The photoelectric conversion element for a photoelectrochemical cell according to appendix 22, wherein a charge transport material is included between the semiconductor electrode for the photoelectrochemical cell and the counter electrode.
(Appendix 24)
A photoelectrochemical cell comprising the photoelectric conversion element for a photoelectrochemical cell according to appendix 22 or appendix 23.
(Appendix 25)
A compound represented by the following general formula (I) and a compound represented by the following general formula (II) are reacted to form a pyrrole ring to produce a pyrrole derivative represented by the following general formula (III). Pyrrole ring formation step;
A halogenation step of producing a halogenated pyrrole derivative represented by the following general formula (IV) by halogenating a pyrrole derivative represented by the following general formula (III);
A cup for producing a compound represented by the following general formula (VI) by coupling a halogenated pyrrole derivative represented by the following general formula (IV) and a halide represented by the following general formula (V): A ring process; and
APPENDIX 1 to APPENDIX 13 including an acidic group introduction step of converting the Q in the following general formula (VI) to introduce an acidic group X to produce the compound represented by the general formula (1) A method for producing a pyrrole compound according to any one of the above, a tautomer or stereoisomer thereof, or a salt thereof.

前記一般式（Ｉ）、一般式（III）、一般式（IV）および一般式（VI）中、
Ｒ^１は、前記一般式（１）中のＲ^１と同じであり、
前記一般式（II）、一般式（III）、一般式（IV）および一般式（VI）中、
Ｒ^２〜Ｒ^４は、前記一般式（１）中のＲ^２〜Ｒ^４と同じであり、
前記一般式（IV）中、
Ｈａｌ^１は、ハロゲンであり、
前記一般式（Ｖ）中、
Ｈａｌ^２は、ハロゲンであり、
Ｈａｌ^１とＨａｌ^２は同一でも異なっていてもよく、
前記一般式（Ｖ）および一般式（VI）中、
Ｚは、前記一般式（１）中のＺと同じであり、
Ｑは、酸性基Ｘに変換可能な任意の置換基である。

In the general formula (I), general formula (III), general formula (IV) and general formula (VI),
R ¹ is the same as R ¹ in the general formula (1),
In the general formula (II), general formula (III), general formula (IV) and general formula (VI),
R ² to R ⁴ are the same as ^R 2 to R ⁴ in the general formula (1),
In the general formula (IV),
Hal ¹ is halogen,
In the general formula (V),
Hal ² is halogen,
Hal ¹ and Hal ² may be the same or different,
In the general formula (V) and the general formula (VI),
Z is the same as Z in the general formula (1),
Q is an optional substituent that can be converted to the acidic group X.

Note that Hal ¹ is a halogen selected from Cl, Br, and I; Hal ² is preferably a halogen selected from Cl, Br, and I. For example, a halogen selected from Cl, Br, I is adopted as Hal ¹ , and after lithiation, a halogen selected from Cl, Br, I is adopted as Hal ² of the general formula (V) It is preferable to perform a coupling reaction with the compound.
(Appendix 26)
The production method according to appendix 25, wherein the pyrrole ring formation step is performed in the presence of an acid catalyst.
(Appendix 27)
In the general formula (V) and the general formula (VI),
Q is an acyl group represented by the following general formula (VII),
In the general formula (I),
X is an acidic group represented by the following general formula (VIII),
27. The production method according to appendix 25 or appendix 26, wherein in the acidic group introduction step, Q is converted to X by reacting with cyanoacetic acid.

前記一般式（VII）および一般式（VIII）中、
Ｒ^１０は、水素原子、置換若しくは無置換のアルキル基、または置換若しくは無置換のアリール基であり、
前記一般式（VIII）中、
−ＣＯＯＨのＨは、例えば、前記一般式（２）と同じＭで置換してもよい。

In the general formula (VII) and general formula (VIII),
R ¹⁰ is a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group,
In the general formula (VIII),
For example, H in —COOH may be substituted with the same M as in the general formula (2).

Claims (10)

A pyrrole compound represented by the following general formula (1), a tautomer or stereoisomer thereof, or a salt thereof.

In the general formula (1),
R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group,
X represents a group having an acidic group,
Z represents a linking group having at least one heterocyclic ring selected from the group consisting of a thiophene ring, a furan ring and a pyrrole ring. The pyrrole compound, its tautomer or stereoisomer, or a salt thereof according to claim 1, wherein X is a group represented by any of the following formulas (Xa) to (Xm): .

In the formulas (Xa) to (Xm),
M represents a hydrogen atom or a salt-forming cation,
B ⁻ represents a hydroxide ion or a salt-forming anion. The pyrrole compound, its tautomer or stereoisomer, or a salt thereof according to claim 1 or 2, wherein Z is an atomic group including a structure represented by the following general formula (3) .

In the general formula (3), R ⁵ and R ⁶ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted linear or branched alkoxy group, R ⁵ and R ⁶ may be connected to each other to form a ring,
Y represents an oxygen atom, a sulfur atom or NRa;
Ra represents a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group. It is represented by the following general formula (4), The pyrrole compound according to any one of claims 1 to 3, its tautomer or stereoisomer, or a salt thereof.

In the general formula (4),
R ^{1 to} R ⁴ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group,
M represents a hydrogen atom or a salt-forming cation,
Z represents a linking group including a structure represented by the following general formula (3).

In the general formula (3),
R ⁵ and R ⁶ each independently represent a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted linear or branched alkoxy group, and R ⁵ and R ⁶ are linked to each other. To form a ring,
Y represents an oxygen atom, a sulfur atom, or NRa;
Ra represents a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, or a substituted or unsubstituted aryl group. A dye for photoelectric conversion, comprising at least one of the pyrrole compound according to any one of claims 1 to 4, a tautomer or stereoisomer thereof, or a salt thereof. A semiconductor electrode for a photoelectrochemical cell, comprising a semiconductor layer containing the photoelectric conversion dye according to claim 5. The semiconductor electrode for photoelectrochemical cells according to claim 6, wherein the semiconductor layer contains titanium oxide or zinc oxide. A photoelectric conversion element for a photoelectrochemical cell, comprising the semiconductor electrode for a photoelectrochemical cell according to claim 6 or 7. Furthermore, it has a counter electrode facing the semiconductor electrode for photoelectrochemical cells,
9. The photoelectric conversion element for a photoelectrochemical cell according to claim 8, further comprising a charge transport material between the semiconductor electrode for the photoelectrochemical cell and the counter electrode. A photoelectrochemical cell comprising the photoelectric conversion element for a photoelectrochemical cell according to claim 8 or 9.

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