JP2008187162A - Photochemical protein complex immobilized transparent electrode and novel compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an photochemical protein complex immobilized on a transparent electrode. <P>SOLUTION: The present invention is characterized in that an vitamin K1 analogue compound having a pyridine ligand and a quinine as a substituent connects the photochemical protein complex with the transparent electrode. The quinine part is connected with the photochemical protein complex, and the pyridine ligand becomes coordinated complex on the transparent electrode, thereby the photochemical protein complex is immobilized on the transparent electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  Electrode, photoelectric conversion element, solar cell, sensor, bio element, biosensor

  The dye-sensitized solar cell invented by Greatzel et al. Is expected to be a next-generation solar cell that can be easily manufactured at low cost because it has a structure in which a dye is adsorbed to titania fine particles on ITO (Patent Document 1). . However, since the conversion efficiency of the dye-sensitized solar cell is about 11%, further improvement of the conversion efficiency is desired. Reasons for lowering the conversion efficiency include low quantum yield, reverse electron transfer, and short absorption wavelength. On the other hand, the photochemical protein complex absorbs visible light of about 700 nm during photosynthesis and realizes highly efficient photoelectric conversion with a quantum yield of about 100%. If a photochemical protein complex having such high-efficiency characteristics can be incorporated into an electrode, a highly efficient solar cell can be realized.

As an example of using a photochemical protein complex as an element, in Patent Document 2 and Non-Patent Document 1, a photoelectric is obtained by incorporating a molecule into a photochemical protein complex and arranging a path in a path different from the original electron transfer path. A conversion element has been devised.
Japanese Patent No. 2664194 Japanese Patent Application No. 2004-75411 N. Terasaki, et al, BBA-Bioenergetics, in press

  However, in the said invention, the terminal group of the said incorporation molecule | numerator was made into the ionic group or the noble metal nanoparticle, and it was difficult to connect transparent electrodes, such as ITO, and a photochemical protein complex. For this reason, the electrode which fixed the photochemical protein complex to the transparent electrode, and the solar cell using the same have not been reported yet.

  An object of the present invention is to solve the above-mentioned problems, and to fix a photochemical protein complex to a transparent electrode.

  The present invention is characterized in that the photochemical protein complex and the transparent electrode are connected by a vitamin K1 analog having a pyridine ligand and a quinone as a substituent. The quinone moiety is connected to the photochemical protein complex, and the pyridine ligand is coordinated to a metal ion complexed on the transparent electrode, thereby immobilizing the photochemical protein complex on the transparent electrode. can do.

  The vitamin K1 analogue used in the present invention is represented by the general formula (1) and has quinone and pyridine ligands as functional groups. Vitamin K1 present in the photochemical protein complex has naphthoquinone, and naphthoquinone is present in the quinone pocket in a form that fits in the back. For this reason, when vitamin K1 in the photochemical protein complex is extracted from the quinone pocket, it can be easily replaced with the above-mentioned vitamin K1 analog having quinone. Thus, since the replaced vitamin K1 analog has a pyridine ligand at the terminal, it is complexed with a metal ion on the transparent electrode surface-modified with a molecule having the same pyridine ligand. A photochemical protein complex can be immobilized thereon.

  The present invention comprises an electrode in which a photochemical protein complex is immobilized on a transparent electrode, a production method thereof, and a novel compound required for immobilization. The electrode of the present invention is shown in FIG. The electrode of the present invention is composed of a photochemical protein complex, a novel vitamin K1 analog represented by the general formula (1), a transparent electrode surface adsorbing ligand having a pyridine ligand, and a metal ion. As shown in FIG. 2, the electrode of the present invention comprises a photochemical protein complex, a vitamin K1 analog, a transparent electrode surface adsorbing ligand having a pyridine ligand, a metal ion, and a bistelpyridine ligand. It is good also as a structure including.

  The manufacturing method is shown below. First, the vitamin K1 analog compound newly developed in the present invention is replaced with vitamin K1 in the photochemical protein complex, and the vitamin K1 analog compound is encapsulated in the photochemical protein complex. In parallel with the above, the transparent electrode is modified. First, the substrate surface is modified by immersing the transparent electrode in a solvent in which molecules such as carboxylic acid and phosphoric acid containing a pyridine ligand as a functional group are dissolved. Next, the modified transparent electrode is immersed in an aqueous solution in which metal ions such as cobalt and iron are dissolved to coordinate the metal ions to the pyridine moiety. Next, the transparent electrode is immersed in an aqueous solution of the photochemical protein complex containing the vitamin K1 analog and the photochemical protein complex is immobilized on the transparent electrode surface. By the above production method, an electrode in which the photochemical protein complex shown in FIG. 1 is immobilized on a transparent electrode can be produced.

  The transparent electrode used in the present invention is preferably an indium tin oxide (ITO) electrode or a fluorine-doped tin oxide (FTO) electrode. In particular, an indium tin oxide (ITO) electrode is preferable.

  The novel vitamin K1 analogue used in the present invention is represented by the general formula (1) shown in Compound 1. R1 represents a hydrogen atom or a methyl group. Has quinone and pyridine ligands as functional groups. R1 is preferably a methyl group. R2 and R3 are substituents of the pyridine ligand, and are preferably a hydrogen atom or a pyridinyl group. In particular, both R2 and R3 are preferably pyridinyl groups. Instead of the quinone shown in the general formula (1), naphthoquinone shown in the general formula (2) or anthraquinone shown in the general formula (3) may be used. X preferably has a linear structure, and preferably contains a linear alkyl chain, a linear branched alkyl chain, or an oligoethylene glycol chain.

Photosystem I (PSI) was extracted with ether as a photochemical protein complex, and vitamin K1 in PSI was extracted. Subsequently, the PSI obtained by removing the vitamin K1 was added to an ethanol / water mixed solvent of the vitamin K1 analog represented by the compound 5 and stirred for 1 day. After the stirring was completed, PSI was taken out from the PSI ethanol / water solution by ultrafiltration using a centrifuge to obtain PSI containing a vitamin K1 analog. When the absorbance change of PSI was measured using light with a wavelength of 701 nm, light absorption at a wavelength of 701 nm was obtained with PSI (a) before taking out vitamin K1 and PSI (c) in which vitamin K1 was replaced with a vitamin K1 analog. However, PSI (b) from which vitamin K1 was removed showed a decrease in absorbance, confirming that PSI was replaced with a vitamin K1 analog (FIG. 3).

  Next, the PSI replaced with the vitamin K1 analog was immobilized on an ITO substrate. First, the substrate surface was modified by immersing ITO in a solvent in which carboxylic acid molecules containing a terpyridine ligand as a functional group were dissolved. Next, the modified ITO was immersed in an aqueous solution in which metal ions such as cobalt and iron were dissolved to coordinate the metal ions to the terpyridine moiety. Next, ITO was immersed in an aqueous solution of PSI encapsulating the above-mentioned vitamin K1 analog and the PSI was immobilized on the ITO surface. The immobilization was confirmed by an electrochemical measurement method. When an electrochemical measurement was performed by differential pulse voltammetry using an electrode having the PSI immobilized on the ITO surface, a peak of PSI-derived porphyrin can be confirmed in the vicinity of 0.5 V (FIG. 4). It was confirmed that PSI was immobilized on the electrode. By the above method, the electrode which fixed the photochemical protein complex shown in FIG. 1 to the transparent electrode was able to be produced.

  In addition to the point that the production method of the present invention is simple and easy to put into practical use, it is possible to produce an electrode having a photoelectric conversion site that could not be achieved by the conventional technique with a quantum yield of about 100%. It can be applied to solar cells and has high industrial utility value. The preparation method includes the equipment required for molecule synthesis and the centrifuge required for incorporating the molecule into the photochemical protein complex. After that, the substrate is immersed in a solvent without the need for a large-scale device. It's just a simple thing to do. In addition, since the quantum yield of the photochemical protein complex is about 100%, it is applied to an electrode for a solar cell having higher performance than an artificial solar cell such as a dye-sensitized solar cell whose quantum yield is less than 100%. It is highly possible.

  Photochemical protein complex-immobilized transparent electrode structure in the present invention   Photochemical protein complex-immobilized transparent electrode structure in the present invention   Change in absorbance of photochemical protein complex using light of wavelength 701 nm in Example 1   Electrochemical measurement result of photochemical protein complex-immobilized transparent electrode in Example 1

Explanation of symbols

1 Transparent electrode 2 Photochemical protein complex

Claims (9)

  An electrode element structure, wherein a photochemical protein complex and a transparent electrode are connected by molecules. An electrode element structure, wherein a photochemical protein complex and a transparent electrode are connected by the following general formula (1).
(In the formula, R1, R4, and R5 each represent a quinone substituent. R1 represents a hydrogen atom or a methyl group. R2 and R3 represent a pyridine ligand substituent. X represents a linear alkyl chain and a linear chain. Indicates a branched alkyl chain or oligoethylene glycol chain.) An electrode element structure, wherein a photochemical protein complex and a transparent electrode are connected by the following general formula (2).
(In the formula, R1 represents a hydrogen atom or a methyl group. R2 and R3 represent substituents of a pyridine ligand. X represents a linear alkyl chain, a linear branched alkyl chain, or an oligoethylene glycol chain.) An electrode element structure, wherein the photochemical protein complex and the transparent electrode are connected by the following general formula (3).
(In the formula, R1 represents a hydrogen atom or a methyl group. R2 and R3 represent substituents of a pyridine ligand. X represents a linear alkyl chain, a linear branched alkyl chain, or an oligoethylene glycol chain.) An electrode element structure, wherein the photochemical protein complex and the transparent electrode are connected by the following general formula (4).
(In the formula, R represents a hydrogen atom or a methyl group. X represents a linear alkyl group, a linear branched alkyl chain or an oligoethylene glycol chain.)   6. The electrode element structure according to any one of claims 1 to 5, wherein the quinone molecule of the photochemical protein complex is deactivated and removed to incorporate the molecule.   The electrode element structure according to any one of claims 1 to 6, wherein the photochemical protein complex is a PSI, PSII or red bacteria photochemical protein complex of cyanobacteria or higher plants.   The electrode element structure according to claim 1, wherein the transparent electrode is an indium tin oxide (ITO) electrode or a fluorine-doped tin oxide (FTO) electrode.   The solar cell which used the said electrode element structure of any one of Claims 1-8 as a photoelectric conversion element.