JP2010031204A - Photosensitizer and photoelectric exchange element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitizer which is used to improve the exchange efficiency of a photoelectric exchange element. <P>SOLUTION: The photosensitizer is a dyestuff which is represented by formula (I) to have an asymmetric carbon at the 3a position (*) or a salt thereof and has an enantiomer excess percentage of 1% e.e. or more, wherein m is an integer of 0-3, n is an integer of 1-4, p is an integer of 0-2, R<SB>1</SB>and R<SB>2</SB>are each hydrogen, alkyl, aralkyl, or alkenyl, R<SB>3</SB>is alkyl, aryl, aralkyl, or a heterocycle residue, R<SB>4</SB>, R<SB>5</SB>, and R<SB>6</SB>are each hydrogen, alkyl, aralkyl, alkoxy, or halogen, R<SB>5</SB>and R<SB>6</SB>may put themselves together to form a ring structure, R<SB>7</SB>and R<SB>8</SB>are each hydrogen, alkyl, or alkoxy, R<SB>9</SB>is hydrogen, alkyl, aralkyl, alkenyl, or aryl, Z<SB>1</SB>is carboxyl, alkoxycarbonyl, or cyano, Z<SB>2</SB>is hydroxy, carboxy, or alkoxycarbonyl, and Z<SB>1</SB>and Z<SB>2</SB>may put themselves together to form a heterocycle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photosensitizer and a photoelectric conversion element using the photosensitizer.

  In recent years, rapid progress of global warming and depletion of fossil fuel resources have become problems, and solutions for this are being studied all over the world. Among them, solar cells using sunlight, which is an endless clean energy source, are attracting attention. Currently, the mainstream is crystalline, polycrystalline, and amorphous silicon solar cells, and the development of highly efficient solar cells using inorganic materials such as gallium and arsenic is also progressing. In addition to high production costs, it has problems such as toxicity of raw materials used.

  On the other hand, a so-called dye-sensitized solar cell (DSC) has been developed in which an organic dye is used as a photosensitizer and a photoelectric conversion element adsorbed on a photo semiconductor fine particle as an electrode (Dye Sensitized Solar Cell, DSC). A dye-sensitized solar cell generally has a structure in which a photoelectrode having a dye adsorbed on a conductive substrate and a counter electrode such as platinum are filled with an iodine-based electrolyte solution. , High-temperature-sintered porous titanium oxide is used as a photoelectrode, and ruthenium dye is adsorbed to it, which can be manufactured with high conversion efficiency and low cost. Expected.

However, many of the high conversion efficiency dyes used in the Gretzell DSC are complexes of rare metals such as ruthenium (for example, Patent Document 1), and there are still problems to be solved in terms of cost and resources. In order to overcome such problems, studies have already been reported on the use of organic dyes that do not contain rare metals as photosensitizers, but the current situation is that the conversion efficiency is low and has not reached the practical level. (For example, patent document 2).
Nature, 353, p737-740 (1991) Japanese Patent No. 3731552 Japanese Patent No. 4080288

  As described above, the conversion efficiency of DSC using a currently known organic dye as a photosensitizer is lower than that of a silicon solar cell, and further improvement in durability is strongly desired.

  The present invention has been made for the purpose of solving the above problems. Specifically, the purpose is to develop a novel organic dye having a conversion efficiency and durability superior to those of conventional organic dyes, and to provide a photoelectric conversion element for DSC at a practical level using it.

  As a result of intensive studies, the present inventors have found that a photoelectric conversion element having high conversion efficiency can be obtained by using an optically active substance represented by the following general formula (I) or (II) as a photosensitizer. The invention has been completed.

That is, the photosensitizer of the present invention is a dye having an asymmetric carbon at the 3a position (*) of the indoline ring represented by the following general formula (I) or a salt thereof, and an enantiomeric excess of the dye or the salt The rate is 1% ee or more.

(In general formula (I), m represents an integer of 0 to 3, n represents an integer of 1 to 4, and p represents an integer of 0 to 2. R ₁ and R ₂ represent a hydrogen atom, an alkyl group, and an aralkyl group. Or an alkenyl group The absolute configuration of the asymmetric carbon moiety at the position 3a (*) may be either R or S. R ₃ represents an alkyl group, an aryl group, an aralkyl group or a heterocyclic residue, R ₄ , R _5, R ₆ is a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group or a halogen atom, R ₅ and bonded to by R ₆ may also form a cyclic structure .R _7, R ₈ are each independently Represents a hydrogen atom, an alkyl group or an alkoxy group, R ₉ represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group or an aryl group, Z ₁ represents a carboxyl group, an alkoxycarbonyl group or a cyano group, and Z ₂ represents a hydroxy group Base A carboxyl group or an alkoxycarbonyl group, Z ₁ and Z ₂ may form a heterocyclic ring.)

The photosensitizer of the present invention is a dye having an asymmetric carbon at the 3a position (*) of the indoline ring represented by the following general formula (II), and the enantiomeric excess of the dye is 1% ee or more It is characterized by being.

(In General Formula (II), m represents an integer of 0 to 3, n represents an integer of 1 to 4, p represents an integer of 1 to 3, and q represents an integer of 1 to 5. R ₁ and R ₂ Represents a hydrogen atom, an alkyl group, an aralkyl group or an alkenyl group, and the absolute configuration of the asymmetric carbon moiety at the 3a position (*) may be either R or S. R ₃ alkyl group, aryl group, aralkyl group or heterocyclic ring R ₄ , R ₅ and R _{6 each} represent a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group or a halogen atom, and R ₅ and R ₆ may combine to form a cyclic structure. R ₇ and R ₈ each independently represents a hydrogen atom, an alkyl group or an alkoxy group, X ₁ represents an oxygen atom, a sulfur atom, a substituted amino group, an alkylene group or an aliphatic condensed ring, and the a1 ring represents X ₁ and four With substituents attached by a categorized nitrogen atom And X ₂ represents a counter anion.)

  The photoelectric conversion device of the present invention is a dye having an asymmetric carbon at the 3a position (*) of the indoline ring represented by the above general formula (I) or (II) or a salt thereof, and an enantiomer of the dye or a salt thereof It has a semiconductor layer adsorbing a photosensitizer having an excess rate of 1% ee or more.

  The photosensitizer of the present invention is a dye represented by the above general formula (I) or (II) or a salt thereof, and its enantiomeric excess is 1% ee or more. By adsorbing to the semiconductor layer of the photoelectric conversion element, it is possible to obtain a photoelectric conversion element having a significantly improved photoelectric conversion efficiency compared to the corresponding racemic photosensitizer. The inventors found for the first time that the excess of this enantiomer leads to an increase in photoelectric conversion efficiency, and the mechanism of action is not necessarily clear, but the orientation between molecules is improved when adsorbed on the electrode. As a result, it is estimated that the electron transfer efficiency is increased and the conversion efficiency is improved.

  In the present invention, the compound represented by the general formula (I) may be any of the free acid represented by the general formula (I) and a salt thereof. Examples of the salt of the compound represented by the general formula (I) include alkali metal salts or alkaline earth metal salts such as lithium, sodium, potassium, magnesium and calcium of carboxylic acid, or tetramethylammonium, tetrabutylammonium, Preferable examples include salts such as alkylammonium salts such as pyridinium, piperidinium and imidazolium.

R ₁ and R ₂ in the general formula (I) represent a hydrogen atom, an alkyl group, an aralkyl group or an alkenyl group, and examples of the alkyl group include linear alkyl groups such as a methyl group, an ethyl group and a propyl group, an isopropyl group, Examples thereof include a branched alkyl group such as an isobutyl group, and a cyclic alkyl group such as a cyclopentyl group and a cyclohexyl group, and these alkyl groups may be further substituted with a substituent described later. The aralkyl group means an alkyl group substituted with an aryl group as described later, and examples thereof include a benzyl group, a phenylethyl group, a methylnaphthyl group, and the like, and these may further have a substituent.
Examples of the alkenyl group include a vinyl group and an aryl group, which may further have a substituent.

  The substituent is not particularly limited, but is an alkyl group, aryl group, cyano group, isocyano group, thiocyanato group, isothiocyanato group, nitro group, nitrosyl group, acyl group, halogen atom, hydroxyl group, phosphate group. Preferred examples include a phosphate ester group, a substituted or unsubstituted mercapto group, a substituted or unsubstituted amino group, a substituted or unsubstituted amide group, an alkoxyl group, an alkoxyalkane group, a carboxyl group, an alkoxycarbonyl group, and a sulfo group. .

  More specifically, preferable examples of the acyl group include an alkylcarbonyl group having 1 to 10 carbon atoms and an arylcarbonyl group. Examples of the halogen atom include atoms such as chlorine, bromine and iodine, and examples of the phosphate ester group include an alkyl phosphate (C1-C4) ester group. Examples of the substituted or unsubstituted mercapto group include a mercapto group and an alkyl mercapto group.

  Examples of the substituted or unsubstituted amino group include an amino group, a mono or dialkylamino group, a mono or diaromatic amino group, and the like, such as a mono or dimethylamino group, a mono or diethylamino group, a mono or dipropylamino group, and a mono Examples thereof include a phenylamino group and a benzylamino group. Examples of the substituted or unsubstituted amide group include an amide group, an alkylamide group, and an aromatic amide group. Examples of the alkoxy group include an alkoxy group having 1 to 10 carbon atoms. Examples of the alkoxyalkyl group include (C1-C10) alkoxy (C1-C4) alkyl groups.

  Examples of the alkoxycarbonyl group include an alkoxycarbonyl group having 1 to 10 carbon atoms. Acid groups such as carboxyl group, sulfo group and phosphate group are metal salts such as lithium, sodium, potassium, magnesium and calcium, and ammonium salts such as tetramethylammonium, tetrabutylammonium, pyridinium, piperidinium and imidazolium. A salt may be formed.

R ₃ in the general formula (I) represents an alkyl group, an aryl group, an aralkyl group or a heterocyclic residue, and examples of the alkyl group and the aralkyl group are the same as those described above. Examples of the aryl group include phenyl, naphthyl, anthranyl, phenanthrenyl, pyrenyl, indenyl, azulenyl, fluorenyl, and the like, and they may further have a substituent. A heterocyclic residue means a group obtained by removing one hydrogen atom from a heterocyclic compound, such as pyridyl, pyrazyl, piperidyl, pyrazolyl, morpholyl, indolinyl, thiophenyl, furyl, oxazolyl, thiazolyl, indolyl, benzothiazolyl, benzo Examples thereof include oxazolyl, quinolyl, rhodanyl and the like, which may further have a substituent.

R ₄ , R ₅ and R ₆ in the general formula (I) represent a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group or a halogen atom, and examples thereof are the same as those described above. A cyclic structure may be formed by combining R ₅ and R ₆ , and examples of the cyclic structure formed at that time include benzene, naphthalene, cyclopentane, cyclopentanone, pyridine, piperidine, piperazine, pyrazole, pyrrole, Examples include imidazole, thiazole, indole, quinoline, carbazole and the like, which may further have a substituent and may further have a cyclic structure as a substituent.

R ₇ and R ₈ in the general formula (I) each independently represent a hydrogen atom, an alkyl group or an alkoxy group, and examples thereof are the same as those described above.
R ₉ in the general formula (I) represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group or an aryl group, and examples thereof are the same as those described above.

Z ₁ in the general formula (I) represents a carboxyl group, an alkoxycarbonyl group or a cyano group, and examples thereof are the same as those described above.
Z ₂ in the general formula (I) represents a hydroxy group, a carboxyl group or an alkoxycarbonyl group, and examples thereof are the same as those described above.
In the general formula (I), Z ₁ and Z ₂ may be bonded to form a heterocyclic ring. Examples of the heterocyclic ring formed at that time include the structures described above for the heterocyclic ring. It may have a substituent and may further have a cyclic structure as a substituent.

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ in the general formula (II) are the same as those in the general formula (I) described above.
X ₁ represents an oxygen atom, a sulfur atom, a substituted amino group, an alkylene group or an aliphatic condensed ring. Examples of the alkylene group include a dimethylmethylene group and a dibutylmethylene group. Examples of the aliphatic condensed ring include cyclopentane, cyclohexane, cyclohexene, cyclohexadiene, and the like, and these may further have a substituent.
The a1 ring represents a heterocycle which may have a substituent bonded to X ₁ by a quaternized nitrogen atom, and examples thereof include the heterocycle as described above, and these may further have a substituent. It may also have a cyclic structure as a substituent.

X ₂ represents a counter anion, for example, a halide ion such as chlorine ion, bromine ion or iodine ion, an aryl sulfonate ion such as tosylate, an alkyl sulfate ion such as methyl sulfate ion, a sulfate ion, a perchlorate ion, or tetrafluoroboron An acid ion, an acetate ion, etc. are mentioned.
The compound represented by the general formula (I) or (II) can take a structural isomer such as a cis isomer or a trans isomer, and any of them can be suitably used as a photosensitizer in the present invention.

  The enantiomeric excess in the present invention is a value representing the excess amount of one stereoisomer present in a mixture of stereoisomers (enantiomers and diastereomers) as a percentage. The enantiomeric excess can be determined by a general method such as liquid chromatography using an optically active column or a polarimeter, but in the present invention, a liquid using an optically active column that can be measured most accurately is used. Determined by chromatography. The enantiomeric excess of the dye that can be used in the present invention is 1% e.e. or more, preferably 20% e.e. or more, more preferably 70% e.e. or more, and even more preferably 90% e.e. or more. Thus, by using an optically active substance as a photosensitizer in a photoelectric conversion element, it is possible to increase the orientation of molecules when dye adsorption occurs on the electrode surface, and as a result, the electron transfer efficiency is racemic. As compared with the case of using, a photoelectric conversion element having excellent conversion efficiency can be obtained.

Specific examples of the compound represented by the general formula (I) used in the present invention are shown below.

Specific examples of the compound represented by the general formula (II) are shown below.

  Next, the synthesis route of the dye represented by the general formula (I) or (II) of the present invention is shown below. An optically active intermediate (2) or (3) having an asymmetric carbon at the 3a position (*) of the indoline ring is synthesized from the intermediate (1) or (4), for example, by reaction of (2) with a halide. Intermediate (5) is obtained. The intermediate (6) can be synthesized from the intermediate (5) or the intermediate (7), and then reacted with a compound having an acidic group or an acidic group precursor to form the general formula (I) or (II). The optically active pigment | dye (8) represented by these can be obtained. Similarly, (9) having the opposite absolute configuration can be obtained from intermediate (3). When the intermediate (4) is used, a racemic dye (10) is obtained.

In these synthetic routes, racemization hardly occurs and can be induced to the dye (8) or (9) while maintaining the optical purity of the compound (2) or (3). From this, when it is difficult to measure the enantiomeric excess of the general formula (I) or (II) itself, by measuring the value of the enantiomeric excess of the intermediate (2) or (3), the general formula ( It can also be enantiomeric excess of I) or (II). In the following synthesis route, R _a represents an alkyl group, R _b represents a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, or a heterocyclic residue, and R _C represents a hydrogen atom, an alkyl group, an aralkyl group, or an allyl group. , A heterocyclic residue, R _d is a substituent having an acidic group, b is an alkenyl group, a heterocyclic residue, and n is an integer of 0 to 3.

  Examples of the synthesis method of intermediate (1) include Fischer's indole synthesis method in which a substituted indole is synthesized by heating an aryl hydrazone produced from a ketone and an aryl hydrazine under an acid catalyst such as sulfuric acid.

  As a method for synthesizing intermediate (2) or (3) having high optical purity from intermediate (1), asymmetric reduction of intermediate (1) or hydride such as sodium borohydride is used as intermediate (1). The racemic intermediate (4) obtained by reduction with a reagent or a catalytic reduction method includes a method obtained by optical resolution such as diastereomeric salt method or separation by chromatographic method. Any method may be used as long as the method is obtained. Intermediate (4) is an amine, and the diastereomeric salt method, in which optical purity is improved by making an optically active acid and salt using its basicity and recrystallizing repeatedly, is considered to be most convenient. . For confirmation of optical purity, a chromatographic method using an optically active column is convenient.

Intermediate (5) can be easily prepared by nucleophilic substitution reaction of intermediate (2) or (3) with alkyl halide or the like, or coupling reaction of aryl halide and intermediate (2) or (3) using palladium catalyst. Can be synthesized. These are substitution reactions on the indoline nitrogen atom, and no racemization occurs in this reaction.
Intermediate (7) can be synthesized with a halogenating agent such as NBS.

  As a synthesis method of intermediate (6) by carbonylation reaction of intermediate (5), acylation reaction represented by Friedel-Crafts reaction, formylation reaction represented by Vilsmeier reaction, or once nitrification is performed. The nitrile group can be converted to a carbonyl group, and any reaction can be used as long as the carbonyl compound can be obtained. In the case of formylation, the Vilsmeier reaction is preferable. .

  As a method of synthesizing intermediate (6) from intermediate (7) (when n = 0), after converting to Mg or Li with a Grignard reagent or an organolithium halogen atom, formate or formamide is used as a formylating agent. Examples thereof include a method for formylation.

  When a conjugated chain is introduced (when n ≠ 0), the intermediate (6) can be synthesized through formylation by the Vilsmeier reaction after extending the conjugated chain by Suzuki coupling or the like. At this time, if a boron compound having a formyl group is used, it is possible to extend the conjugated chain and introduce the formyl group in one step. Suzuki coupling is a method in which an organic halogen compound and an organic boron compound are cross-coupled in the presence of a palladium catalyst, and is widely used because of relatively mild conditions and high functional group selectivity.

  Methods for condensing the intermediate (6) with a compound having an acidic group or an acidic group precursor to obtain the dye (8) include a method by reaction of a carbonyl compound and active methylene, such as aldol condensation and Knoevenagel condensation, and Wittig reaction. Examples include olefin synthesis methods.

  In the photoelectric conversion element of the present invention, a substrate having conductivity on the surface, a semiconductor layer in which an oxide semiconductor layer is formed and a dye is adsorbed thereto, an electrolyte layer, and a counter electrode are laminated in this order. As the substrate having conductivity, a substrate such as a metal having conductivity in the support itself, or glass or plastic can be used as the support in the case of having a conductive layer on the surface. In this case, as the material of the conductive layer, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), gold, platinum, or a combination of these can be used, and this can be applied to a substrate by vacuum evaporation, By forming the conductive layer directly by a method such as sputter deposition, ion plating, chemical vapor deposition (CVD), or by attaching a film on which these are formed to a substrate, A substrate having conductivity on the surface can be formed.

  Specific examples of the oxide semiconductor include oxides of titanium, tin, zinc, tungsten, zirconium, gallium, indium, yttrium, niobium, tantalum, vanadium, and the like. Of these, oxides such as titanium, tin, zinc, niobium, and tungsten are preferable. Among these, (1) it is inexpensive, (2) it is easy to form a porous body, and (3) it is conductive as an electrode. From the viewpoints of durability, durability, stability and safety, and (4) compatibility of energy levels with the photosensitizer synthesized in the present invention, titanium and zinc oxides are more preferable. These oxide semiconductors may be used alone or in combination of two or more.

  The oxide semiconductor layer can be formed to be porous on the substrate by applying fine particles of the oxide semiconductor on the substrate and then heat-treating or electrodeposition with an electric furnace or microwave.

  As a method for adsorbing the dye to the oxide semiconductor layer, a method such as immersing the substrate on which the oxide semiconductor layer is formed in a dye solution or a dye dispersion can be used. Can be formed. The concentration of the solution can be determined appropriately depending on the dye, and specific examples of solvents that can be used to dissolve the dye include methanol, ethanol, acetonitrile, dimethyl sulfoxide, dimethylformamide, acetone, and t-butanol. Preferably mentioned.

  In addition, when adsorb | sucking a pigment | dye to the thin film of oxide semiconductor fine particles, you may add an adsorption promoter to a pigment | dye solution. Adsorption promoters include steroidal compounds such as cholic acid, crown ether, cyclodextrin, calixarene, polyethylene oxide, etc., but deoxycholic acid, dehydrodeoxycholic acid, chenodeoxycholic acid, cholic acid methyl ester, cholic acid Sodium and the like are more preferable.

  The electrolyte layer is a mixed liquid of acetonitrile and ethylene carbonate, a liquid electrolyte in which an electrolyte made of iodide such as metal iodine or lithium iodide is added using methoxypropionitrile as a solvent, a polymer gel electrolyte, etc. It can be formed using a solid electrolyte such as a solidified electrolyte, a p-type semiconductor, and a hole transport agent.

  The counter electrode may be prepared in the same manner as the conductive substrate when transparency is required, or it may be prepared using carbon, a conductive polymer, a general metal, etc. when transparency is not required. be able to.

Hereinafter, the photoelectric conversion device of the present invention will be described in more detail with reference to examples. The structures of indoline, intermediates (A-1), (B-1) to (B-7), and (C-1) to (C-9) in the following examples are represented by the following chemical formulas. It is.

<Synthesis of racemic indoline>
Cyclopentanone (42.5 g) was dissolved in acetic acid (190 g), and phenylhydrazine (54.5 g) was added dropwise with stirring at 120 ° C. After stirring for 1 hour at the same temperature, the mixture was allowed to cool to room temperature, and water (500 g) was added to precipitate the product, which was filtered off. The obtained solid was purified by column chromatography to obtain brown crystals (56.0 g). Next, the brown crystals (56.0 g) were dissolved in toluene (700 ml), palladium carbon (2.5 g) was added, and the mixture was stirred at room temperature for 10 hours under a hydrogen atmosphere of 4 atm. After stirring, palladium on carbon was filtered off and the filtrate was concentrated under reduced pressure to obtain racemic indoline. 52.5g. Yield 65%.

<Optical resolution of racemic indoline>
Racemic indoline and equimolar D-phenylglycine optical resolution agent were dissolved in water, and heated and stirred at 90 ° C. After stirring for 1 hour, the mixture was allowed to cool to room temperature, and the precipitated solid was filtered off. The obtained solid was recrystallized from water. An optically active indoline was obtained by subjecting the salt obtained by repeating this three times to alkali treatment. HPLC analysis of racemic indoline and optically active indoline obtained in this step was performed with a chiral column (CHIRALPAK AD-H manufactured by Daicel Chemical Industries, Ltd., developing solvent: hexane / ethanol = 90/10), and the resulting chromatogram was obtained. Shown in FIGS. In the chromatogram of racemic indoline in FIG. 1, there are two peaks having equivalent area values at RT = 9.9 min and 10.7 min. However, the optically active indoline obtained by the above method in FIG. In the chromatogram, only a peak of approximately RT = 9.9 minutes was observed, and the optical purity was 99% ee. Similarly, when an optical resolution operation is performed using an L-phenylglycine optical resolution agent, an optically active indoline having a peak at RT = 10.7 minutes can be obtained with an optical purity of 99% ee. It was. Hereinafter, the optically active indoline corresponding to RT = 9.9 minutes is referred to as indoline (a), and the optically active indoline corresponding to RT = 10.7 minutes is referred to as indoline (b).
In addition, in the following, what added and described a and b like (B-1a), (B-1b), (I-1a), (II-24a), etc. is the raw material indoline (a) Or the enantiomer corresponding to (b) is shown.

<Dye synthesis flow>
In the following examples, a typical dye synthesis flow is shown in the following diagram. First, the bromo intermediate (A-1) was reacted with optically active or racemic indoline to introduce an aryl group on the nitrogen atom of indoline. Next, in the case of compounds (I-1), (I-19), (I-32), (II-24), etc. that do not have a thiophene ring, a formyl group is introduced by the Vilsmeier reaction, and active methylene or methyl Obtained by condensing with compound. In the case of the compound (I-10) having a thiophene ring, an aryl group is introduced into the nitrogen atom of indoline, then brominated by a conventional method using NBS, reacted with boronic acids, and this is induced to an aldehyde by Vilsmeier reaction. Obtained by condensation with an active methylene compound. In addition, the desired enantiomer or racemic dye was obtained by using indoline (a), indoline (b), or racemic indoline as the starting indoline of the following flow.

<Synthesis of Intermediate>
(Synthesis of Intermediate (B-1a))
(Indoline a) (optical purity 99% ee 1.1 g), bromo intermediate (A-1) (manufactured by Tokyo Chemical Industry Co., Ltd.) (2.4 g), palladium (II) acetic acid (7.5 mg) After dissolving in xylene (16 ml) and adding tri-t-butylphosphine (2 drops), the mixture was heated and stirred at 125 ° C. After 2 hours, the heating was stopped, and the mixture was cooled to room temperature and filtered. The filtrate was dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain a brown oil (3.0 g). Next, this brown oil (3.0g) was dripped at the Vilsmeier reagent prepared by dripping phosphoryl chloride (1.8g) in DMF (2.2g) under ice cooling, and it stirred at room temperature. After 3 hours, the reaction solution was poured into an ice-cooled 2% aqueous sodium hydroxide solution (60 ml), stirred at room temperature for 1 hour, extracted with chloroform, concentrated under reduced pressure, and the residue was purified by column chromatography. (B-1a) was obtained. 2.5g. Yield 85%. [lambda] _max = 395 nm (chloroform).

(Synthesis of intermediates (B-5a, 6a, 7a), (B-1b, 5b, 6b, 7b) and (B-1 racemic, 5 racemic, 6 racemic, 7 racemic))
Intermediate (B-5a) (B-6a) (B-7a) was synthesized in the same manner as described above (Synthesis of Intermediate (B-1a)) using the corresponding bromo intermediate. Intermediates (B-1b) (B-5b) (B-6b) (B-7b) and (B-1 racemic) (B-5 racemic) (B-6 racemic) (B-7 racemic) Were synthesized in the same manner using (indoline b: optical purity 99% ee) or (racemic indoline), respectively.

(Synthesis of intermediates (B-2a, 3a, 4a), (B-2b, 3b, 4b) and (B-2 racemic, 3 racemic, 4 racemic))
Intermediates (B-2a), (B-3a) and (B-4a) are the same methods as described in the above (Synthesis of intermediate (B-1a)) for indoline a and bromo intermediate (A-1). And then brominated with NBS, reacted with boronic acids, and synthesized with a Vilsmeier reagent. Intermediates (B-2b) (B-3b) (B-4b) and (B-2 racemic) (B-3 racemic) (B-4 racemic) are also represented by (indoline b) or (racemic indoline), respectively. It was synthesized by the same method used.

(Synthesis of Intermediate (C-1, 2, 3, 4, 5))
Intermediates (C-1), (C-2), (C-3), (C-4), and (C-5) were synthesized according to the method described in JP-A-8-269345.

(Intermediate C-6, 7)
About intermediate body (C-6) (C-7), what was purchased from Sigma-Aldrich Japan Co., Ltd. was used.

(Intermediate C-8, 9)
Intermediate (C-8) (C-9) used was synthesized according to the method described in JP-A-4-275542.

<Synthesis of Example 1 (I-1a)>
Intermediate (B-1a) (0.80 g), cyanoacetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) (0.31 g) and piperidine (0.5 ml) were dissolved in acetonitrile (15 ml), and the mixture was heated and stirred at 85 ° C. . After 4 hours, heating was stopped, cooled to room temperature, and treated with hydrochloric acid. The mixture was extracted with chloroform, and the chloroform layer was washed twice with water (20 ml) and then dried over anhydrous sodium sulfate, and the solvent was distilled off. The resulting crude crystals were purified by column chromatography to obtain compound (I-1a). 0.77g. Yield 84%. λ _max = 464 nm (chloroform).

<Synthesis of Example 2 (I-1b)>
Using a method similar to that in Example 1, intermediate (B-1b) was used to obtain compound (I-1b). λ _max = 464 nm (chloroform).

<Synthesis of Example 3 (I-19a)>
Intermediate (B-1a) (1.50 g), rhodanine-3-acetic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) (0.65 g) and ammonium acetate (0.09 g) were dissolved in acetic acid (15 ml), and 125 ° C. And stirred with heating. After 6 hours, heating was stopped and the solution solidified when cooled to room temperature. The crude crystals were separated by filtration and washed with methanol to obtain compound (I-19a). 2.05g. Yield 98%. λ _max = 516 nm (chloroform).

<Synthesis of Example 4 (I-19b)>
Using a method similar to that in Example 3, and using intermediate (B-1b), compound (I-19b) was obtained. λ _max = 516 nm (chloroform).

<Synthesis of Example 5 (I-32a)>
Intermediate (B-1a) (5.74 g), intermediate (C-1) (4.14 g) and ammonium acetate (0.10 g) were dissolved in acetic acid (200 ml), and the mixture was heated and stirred at 125 ° C. After 6 hours, heating was stopped and the solution solidified when cooled to room temperature. The crude crystals were filtered off and subjected to column chromatography to obtain compound (I-32a). 3.12 g. Yield 32%. λ _max = 554 nm (chloroform).

<Synthesis of Example 6 (I-32b)>
Using a method similar to that in Example 5, and using intermediate (B-1b), compound (I-32b) was obtained. λ _max = 554 nm (chloroform).

<Synthesis of Example 7 (I-49a)>
Using a method similar to that in Example 5, and using intermediate (C-3), compound (I-49a) was obtained. λ _max = 552 nm (chloroform).

<Synthesis of Example 8 (I-49b)>
Using a method similar to that in Example 5, intermediate (B-1b) and intermediate (C-3) were used to obtain compound (I-49b). λ _max = 552 nm (chloroform).

<Synthesis of Example 9 (II-24a)>
Intermediate (B-1a) (2.09 g) and intermediate (C-9) (1.44 g) were dissolved in acetic anhydride (10 ml), and the mixture was heated and stirred at 100 ° C. After 1 hour, heating was stopped and the solution solidified when cooled to room temperature. Crude crystals were filtered off and purified by column chromatography to obtain compound (II-24a). 1.91 g. Yield 56%. λ _max = 606 nm (chloroform).

<Synthesis of Example 10 (II-24b)>
Using a method similar to that in Example 9, and using intermediate (B-1b), compound (II-24b) was obtained. λ _max = 606 nm (chloroform).

<Synthesis of Comparative Example 1 (I-1 Racemic)>
The compound (I-1 racemic) was obtained by using the intermediate (B-1 racemic) in the same manner as in Example 1. λ _max = 464 nm (chloroform).

<Synthesis of Comparative Example 2 (I-19 Racemic)>
Using the same method as in Example 3, the intermediate (B-1 racemic) was used to obtain the compound (I-19 racemic). λ _max = 516 nm (chloroform).

<Synthesis of Comparative Example 3 (I-32 racemic)>
The compound (I-32 racemic) was obtained by using the same method as in Example 5 and using the intermediate (B-1 racemic). λ _max = 554 nm (chloroform).

<Synthesis of Comparative Example 4 (I-49 racemic)>
The compound (I-49 racemic) was obtained by using the intermediate (B-1 racemic) and the intermediate (C-3) in the same manner as in Example 5. λ _max = 552 nm (chloroform).

<Synthesis of Comparative Example 5 (II-24 Racemic)>
The compound (II-24 racemic) was obtained by using the intermediate (B-1 racemic) in the same manner as in Example 9. λ _max = 606 nm (chloroform).

<Production of photoelectric conversion element>
(Preparation of photoelectrode layer)
Using an FTO glass having an FTO electrode film formed on one side as an electrode substrate, a zinc oxide porous film having a thickness of 3 μm was formed on the electrode surface of the FTO glass by electrodeposition. Each dye obtained in Examples 1 to 10 and Comparative Examples 1 to 5 was dissolved in ethanol so that the concentration of the FTO glass on which the zinc oxide porous body film was formed was 200 μM, and this solution was dissolved in this solution for 1 hour. A photoelectrode layer was prepared by dipping. When cholic acid was added as an additive, deoxycholic acid was added to this dye solution so that the deoxycholic acid concentration was 400 μM.

(Formation of electrolyte layer)
To a solution in which acetonitrile and ethylene carbonate are mixed at a volume ratio of acetonitrile: ethylene carbonate = 1: 4, tetrapropylammonium iodide and iodine are mixed with tetrapropylammonium iodide 0.5 mol / l and iodine 0.5 mol / l. The mixture was mixed to obtain an electrolyte solution. This electrolyte solution was disposed between the counter substrate using the same FTO glass as the electrode base material and the above-described photoelectrode layer, thereby forming an electrolyte layer.

<Evaluation>
Each photoelectric conversion element produced above (light receiving area 4 mm × 5 mm) was irradiated with light at an irradiation intensity of 100 mW / cm ² using “CEP-2000” manufactured by Spectrometer Co., Ltd., and the photoelectric conversion element was short-circuited. The current (mA) and the open circuit voltage (V) were measured, and the short circuit current density (mA / cm ² ) was determined from the short circuit current and the light receiving area. Subsequently, the resistance value connected between the electrodes of the photoelectric conversion element was changed to observe the maximum power Wmax (mW), and the form factor and the photoelectric conversion efficiency (%) were obtained by the following formula.

The results are shown in Table 1. The optical purity of each of the dyes of Examples 1 to 10 is 99% ee because the optical purity of indoline a and indoline b, which are raw materials for the intermediate, is maintained at 99% ee.

  As shown in Table 1, in all Examples, when an optically active photosensitizer was used, an improvement in photoelectric conversion efficiency was observed as compared to the case where the corresponding racemate was used. . In general, since an electrode is an inorganic substance having no asymmetry, it has been considered that the effect cannot be obtained even if an optically active substance is used as a photosensitizer. However, according to the present invention, an improvement in photoelectric conversion efficiency of about 1% at the maximum can be expected, which is a surprising result in the zinc oxide electrode DSC having a maximum conversion efficiency of 7-8%. The reason for the improvement in photoelectric conversion efficiency is considered to be that the state of aggregation of the dye molecules on the adsorption surface is improved by using an optically active photosensitizer, so that the efficiency of electron transport is improved. Such an effect has not been known so far and has been found for the first time by the present invention. In addition, in the present invention, for comparison with the racemate, the photoelectric conversion element is studied under the same conditions. However, the dye adsorption time and the like are optimized by taking into consideration the properties specific to the optically active dye. If this is done, further improvement in conversion efficiency can be expected.

  Here, since the enantiomeric dyes a and b have comparable conversion efficiencies, it was also found that the performance as a photosensitizer is not affected by the absolute configuration. In addition, since the conversion efficiency superior to the case where cholic acid was not added was shown, cholic acid was always added in the following examples, and the racemate and enantiomer a were compared.

<Synthesis of Example 11 (I-8a)>
Intermediate (B-1a) (4.41 g), cyanoacetic acid (1.70 g) and piperidine (2 ml) were dissolved in acetonitrile (60 ml), and the mixture was heated and stirred at 85 ° C. After 4 hours, heating was stopped and the solution solidified when cooled to room temperature. The crude crystals were separated by filtration and washed with acetonitrile to obtain Compound (I-8a). 5.60 g. Yield 94%. λ _max = 464 nm (chloroform).

<Synthesis of Example 12 (I-9a)>
Using a method similar to that in Example 11, compound (I-9a) was obtained from intermediate (B-6a). λ _max = 460 nm (chloroform).

<Synthesis of Example 13 (I-10a)>
Using a method similar to that in Example 1, compound (I-10a) was obtained from intermediate (B-2a). λ _max = 519 nm (chloroform).

<Synthesis of Example 14 (I-11a)>
Using a method similar to that in Example 1, compound (I-11a) was obtained from intermediate (B-3a). λ _max = 517 nm (chloroform).

<Synthesis of Example 15 (I-12a)>
Using a method similar to that in Example 1, compound (I-12a) was obtained from intermediate (B-4a). λ _max = 519 nm (chloroform).

<Synthesis of Example 16 (I-33a)>
Using a method similar to that in Example 5, compound (I-33a) was obtained from intermediate (C-2). λ _max = 521 nm (chloroform).

<Synthesis of Example 17 (I-35a)>
Using a method similar to that in Example 5, compound (I-35a) was obtained from intermediate (B-5a). λ _max = 539 nm (chloroform).

<Synthesis of Example 18 (I-38a)>
Using a method similar to that in Example 5, compound (I-38a) was obtained from intermediate (B-6a). λ _max = 544 nm (chloroform).

<Synthesis of Example 19 (I-54a)>
Using a method similar to that in Example 5, compound (I-54a) was obtained from intermediate (C-4). λ _max = 556 nm (chloroform).

<Synthesis of Example 20 (I-66a)>
Using a method similar to that in Example 5, compound (I-66a) was obtained from intermediate (C-5). λ _max = 574 nm (chloroform).

<Synthesis of Example 21 (I-70a)>
Intermediate (B-1a) (1.77 g) and intermediate (C-6) (0.88 g) were dissolved in ethanol (50 ml) and heated and stirred at 90 ° C. After 6 hours, heating was stopped and the solution solidified when cooled to room temperature. The crude crystals were filtered off and washed with ethanol to obtain compound (I-70a). 2.45 g. Yield 97%. λ _max = 554 nm (chloroform).

<Synthesis of Example 22 (I-73a)>
Using a method similar to that in Example 21, compound (I-73a) was obtained from intermediate (C-7). Yield 96%. λ _max = 511 nm (chloroform).

<Synthesis of Comparative Example 6 (I-8 racemic)>
Using the same method as in Example 11, the intermediate (B-1 racemic) was used to obtain the compound (I-8 racemic). λ _max = 464 nm (chloroform).

<Synthesis of Comparative Example 7 (I-9 racemic)>
The compound (I-9 racemic) was obtained by using the intermediate (B-6 racemic) in the same manner as in Example 11. λ _max = 460 nm (chloroform).

<Synthesis of Comparative Example 8 (I-10 Racemic)>
In the same manner as in Example 1, the compound (I-10 racemic) was obtained from the intermediate (B-2 racemic). λ _max = 519 nm (chloroform).

<Synthesis of Comparative Example 9 (I-11 Racemic)>
In the same manner as in Example 1, the compound (I-11 racemic) was obtained from the intermediate (B-3 racemic). λ _max = 517 nm (chloroform).

<Synthesis of Comparative Example 10 (I-12 racemic)>
In the same manner as in Example 1, the compound (I-12 racemic) was obtained from the intermediate (B-4 racemic). λ _max = 519 nm (chloroform).

<Synthesis of Comparative Example 11 (I-33 racemic)>
In the same manner as in Example 5, compound (I-33 racemic) was obtained from intermediate (B-1 racemic) and intermediate (C-2). λ _max = 521 nm (chloroform).

<Synthesis of Comparative Example 12 (I-35 racemic)>
In the same manner as in Example 5, the compound (I-35 racemic) was obtained from the intermediate (B-5 racemic). λ _max = 539 nm (chloroform).

<Synthesis of Comparative Example 13 (I-38 racemic)>
In the same manner as in Example 5, the compound (I-38 racemic) was obtained from the intermediate (B-6 racemic). λ _max = 544 nm (chloroform).

<Synthesis of Comparative Example 14 (I-54 racemic)>
Using a method similar to that in Example 5, compound (I-54 racemic) was obtained from intermediate (B-1 racemic) and intermediate (C-4). λ _max = 556 nm (chloroform).

<Synthesis of Comparative Example 15 (I-66 Racemic)>
In the same manner as in Example 5, compound (I-66 racemic) was obtained from intermediate (B-1 racemic) and intermediate (C-5). λ _max = 574 nm (chloroform).

<Synthesis of Comparative Example 16 (I-70 racemic)>
Using a method similar to that in Example 21, the compound (I-70 racemic) was obtained from the intermediate (B-1 racemic). λ _max = 554 nm (chloroform).

<Synthesis of Comparative Example 17 (I-73 racemic)>
Using a method similar to that in Example 21, the compound (I-73 racemic) was obtained from the intermediate (B-1 racemic) and the intermediate (C-7). λ _max = 511 nm (chloroform).

Using each dye obtained in Examples 11 to 22 and Comparative Examples 6 to 17, photoelectric conversion elements were produced in the same manner as in Examples 1 to 10, and the same evaluation was performed. The results are shown in Table 2.

  As is clear from Table 2, as in Examples 1 to 10, the optically active dye showed an excellent conversion efficiency compared to the racemate. From this, in the case of the zinc oxide electrode layer, the conversion efficiency could be improved by using an optically active substance as a photosensitizer. Subsequently, it was examined whether the same effect can be obtained even when other metal oxides are used as the electrode layer.

<Synthesis of Example 23 (I-22a)>
Using a method similar to that in Example 3, and using intermediate (B-7a), compound (I-22a) was obtained. λ _max = 509 nm (chloroform).

<Synthesis of Example 24 (II-14a)>
Exemplified compound (II-14a) was obtained by using the intermediate (B-7a) and intermediate (C-8) in the same manner as in Example 9. λ _max = 603 nm (chloroform).

<Synthesis of Comparative Example 18 (I-22 racemic)>
Using the same method as in Example 3, the intermediate (B-7 racemic) was used to obtain the compound (I-22 racemic). λ _max = 509 nm (chloroform).

<Synthesis of Comparative Example 19 (II-14 Racemic)>
Using the same method as in Example 9, the intermediate compound (B-7 racemic) and the intermediate (C-8) were used to obtain the exemplified compound (II-14 racemic). λ _max = 603 nm (chloroform).

<Production of photoelectric conversion element>
(Preparation of photoelectrode layer)
Using FTO glass with an FTO electrode film formed on one side as an electrode substrate, a titanium oxide paste was applied to the electrode surface of this FTO glass so as to have a thickness of 12 μm, dried at room temperature, and then heated at 100 ° C. Calcination was carried out for 1 hour at 550 ° C. for another hour to form a porous titanium oxide film. Using the respective dyes obtained in Examples 1, 3, 5, 20, 23, and 24 and Comparative Examples 1 to 3, 15, 18, and 19, the FTO glass on which this titanium oxide porous body film was formed was used. Each dye was dissolved in ethanol so that the concentration was 200 μM and immersed in this solution for 1 hour to prepare a photoelectrode layer. To this dye solution, deoxycholic acid was added to this dye solution so that the deoxycholic acid concentration was 400 μM.

(Formation of electrolyte layer)
An electrolyte layer was formed in the same manner as the zinc oxide electrode except that the electrode layer was made of the above titanium oxide.

<Evaluation>
Evaluation was performed in the same manner as the zinc oxide electrode except that the electrode layer was made of the above titanium oxide. The results are shown in Table 3.

  As can be seen from Table 3, when titanium oxide was used for the electrode layer, as in the case of zinc oxide, it was found that the optically active dye showed superior conversion efficiency compared to the racemic body. From these things, even if it was a photoelectric conversion element using what kind of metal oxide, the conversion efficiency could be improved by using an optically active pigment | dye as a photosensitizer.

Racemic Indoline HPLC Chart HPLC chart of optically active indoline

Claims (3)

A dye or a salt thereof having an asymmetric carbon at the 3a position (*) of the indoline ring represented by the following formula (I), wherein the enantiomeric excess of the dye or the salt is 1% ee or more Photosensitizer.

(In the formula (I), m represents an integer of 0 to 3, n represents an integer of 1 to 4, and p represents an integer of 0 to 2. R ₁ and R ₂ represent a hydrogen atom, an alkyl group, an aralkyl group, or Represents an alkenyl group, and the absolute configuration of the asymmetric carbon moiety at the 3a position (*) may be either R or S. R ₃ represents an alkyl group, an aryl group, an aralkyl group or a heterocyclic residue, R ₄ , R _5, R ₆ is a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group or a halogen atom, R ₅ and bonded to by R ₆ may also form a cyclic structure .R _7, R ₈ are each independently A hydrogen atom, an alkyl group or an alkoxy group, R ₉ represents a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group or an aryl group, Z ₁ represents a carboxyl group, an alkoxycarbonyl group or a cyano group, and Z ₂ represents a hydroxy group , Mosquito It indicates Bokishiru group or an alkoxycarbonyl group, Z ₁ and Z ₂ may form a heterocyclic ring.) A dye or a salt thereof having an asymmetric carbon at position 3a (*) of the indoline ring represented by the following formula (II), wherein the enantiomeric excess of the dye or the salt is 1% ee or more, Photosensitizer.

(In Formula (II), m represents an integer of 0 to 3, n represents an integer of 1 to 4, p represents an integer of 1 to 3, and q represents an integer of 1 to 5. R ₁ and R ₂ represent Represents a hydrogen atom, an alkyl group, an aralkyl group or an alkenyl group, and the absolute configuration of the asymmetric carbon moiety at the 3a position (*) may be either R or S. R ₃ represents an alkyl group, aryl group, aralkyl group or heterocyclic ring R ₄ , R ₅ and R _{6 each} represent a hydrogen atom, an alkyl group, an aralkyl group, an alkoxy group or a halogen atom, and R ₅ and R ₆ may combine to form a cyclic structure. R ₇ and R ₈ each independently represents a hydrogen atom, an alkyl group or an alkoxy group, X ₁ represents an oxygen atom, a sulfur atom, a substituted amino group, an alkylene group or an aliphatic condensed ring, and the a1 ring represents X ₁ and four With a substituent attached by a categorized nitrogen atom And X ₂ represents a counter anion.   It has a semiconductor layer which adsorb | sucked the photosensitizer of Claim 1 or 2. The photoelectric conversion element characterized by the above-mentioned.

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