CN101851255B - The manufacture method of ruthenium complex - Google Patents

Abstract

The invention provides a method for producing a ruthenium complex, which can synthesize Ru(dcbpy) ₂ (NCS) ₂ in a short time. The manufacturing method includes: first step, reacting RuCl ₃ ·3H ₂ O with dcbpy to synthesize intermediate Ru(II)(dcbpy) ₂ Cl ₂ ; and second step, adding NH ₄ NCS to synthesize Ru(dcbpy) ₂ ( NCS) ₂ , wherein, after synthesizing the intermediate Ru(II)(dcbpy) ₂ Cl ₂ , instead of separating and purifying Ru(II)(dcbpy) ₂ Cl ₂ , the first step and the second step The reactions were carried out in the same reaction vessel (one-pot method). For each reaction in the first and second steps of the one-pot method, optimizing the reaction conditions can shorten the synthesis time and reduce the formation of isomers, and can obtain Ru(dcbpy) ₂ with high purity, high yield and low cost (NCS) ₂ .

Description

The manufacture method of ruthenium complex

technical field

The present invention relates to the manufacture method that can be applicable to the ruthenium complex compound of dye-sensitized solar cell, relate in particular to short-time, high-purity, high-yield synthesis cis-bis(isothiocyanato)-bis(2,2 '-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) complex method.

Background technique

A solar cell utilizing sunlight has attracted attention as an energy source to replace fossil fuels, and various researches have been conducted on it. A solar cell is a photoelectric conversion device that converts light energy into electrical energy. Since it uses sunlight as an energy source, it has minimal impact on the global environment and is expected to be widely used.

Dye-sensitized solar cells (hereinafter abbreviated as DSSC (Dye-Sensitized Solar Cell)) using light-induced electron movement sensitized by dyes have been receiving attention in recent years as next-generation solar cells replacing silicon (Si)-based solar cells. attention and has been extensively studied. As the sensitizing dye, a substance capable of effectively absorbing light in the vicinity of visible light, such as a ruthenium (Ru) complex, etc., is used.

As a dye-sensitized solar cell, since it has high photoelectric conversion efficiency, does not require expensive manufacturing equipment such as a vacuum device, and can be easily manufactured with good productivity using cheap semiconductor materials such as titanium oxide, it is expected to become A new generation of solar cells.

Now many research institutes are vigorously researching, by containing 2,2'-bipyridine-4,4'-dicarboxylic acid (also known as 4,4'-dicarboxy-2,2'-bipyridine, hereinafter referred to as Nanocrystalline titanium dioxide sensitized with ruthenium(II) complexes for "dcbpy" or "L") ligands.

The mesoporous porous titania film with sensitizing dye adsorbed is a key part to ensure new solar cells with 10% to 11% photoelectric conversion efficiency. In addition, when the ruthenium complex is used as a sensitizer, the solar cell shows good stability, and its practical application becomes possible.

At present, in dye-sensitized solar cells, cis-bis(isothiocyano)-bis(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(II) known as N3 and N719 respectively ) complex (hereinafter referred to as "Ru(dcbpy) ₂ (NCS) ₂ " or "RuL ₂ (NCS) ₂ "), cis-bis(isothiocyanato)-bis(2,2'-bipyridine -4,4'-dicarboxylic acid) ruthenium (II) di-tetrabutylammonium complex, which is widely studied and used. However, their high cost limits their application in dye-sensitized solar cells.

There have been many literature reports on the synthesis of ruthenium complex dyes, for example, the following reports.

First, Non-Patent Document 1 described later describes a method for synthesizing cis-Ru(II)(dcbpy) ₂ Cl ₂ , which includes combining RuCl ₃ ·3H ₂ O with a ligand (dcbpy, 2, 2'-bipyridine-4,4'-dicarboxylic acid) in DMF (dimethylformamide) under reflux for 8 hours.

In addition, the synthetic method of Ru(dcbpy) ₂ (NCS) ₂ is described in the non-patent document 2 and patent document 1 mentioned later, including the following steps: that is, under the condition of avoiding light, Ru(II)(dcbpy ) ₂ Cl ₂ was dissolved in DMF, and an aqueous solution of NaNCS was added to the obtained solution, and then, the reaction mixture was heated and refluxed for 6 hours under nitrogen protection while stirring.

In addition, in Non-Patent Document 3 described later, a method for synthesizing Ru(II)(dcbpy) ₂ Cl ₂ and Ru(dcbpy) ₂ (NCS) ₂ is described and described below.

The synthesis of Ru(II)(dcbpy) ₂ Cl ₂ includes the step of dissolving RuCl ₃ (H ₂ O) ₃ in DMF in Ar and, after stirring, in the solution further added with DMF , add 2,2'-bipyridine-4,4'-dicarboxylic acid as a ligand, and heat to reflux for 3 hours in the dark under Ar atmosphere under the condition of 170°C to 180°C.

The synthesis of Ru(dcbpy) ₂ (NCS) ₂ includes the following steps: adding DMF to the aqueous solution of KNCS in a three-necked flask, then adding Ru(II)(dcbpy) ₂ Cl ₂ in the dark, and refluxing for 5 hours.

In addition, Patent Document 2, which will be described later, entitled "Method for Producing Ruthenium Complex", has the following description.

(1) A method for producing a ruthenium complex represented by the general formula RuL ₂ (SCN) ₂ 2H ₂ O (L is 2,2'-bipyridine-4,4'-dicarboxylic acid), characterized in that: The purified trivalent ruthenium chloride (RuCl ₃ ·3H ₂ O) and the ligand (L: 2,2'-bipyridine-4,4'-dicarboxylic acid) react in an organic solvent by heating to generate RuL ₂ Cl ₂ ·2H ₂ O, then, the obtained reaction product is dissolved in an organic solvent, the dissolved product is reacted with sodium thiocyanate by heating, and the obtained RuL ₂ (SCN) ₂ ·2H ₂ O is mixed with hydroxypropyl The cross-linked dextran was used as a packing column for purification.

In addition, preferred embodiments are: (2) the method for producing a ruthenium complex according to (1), which is characterized in that the heating reaction is performed at 110 to 150° C., and (3) the production method for a ruthenium complex according to (1) The method is characterized in that the heating reaction is carried out in the presence of an inert gas and under the condition of avoiding light.

In addition, there is the following description in Patent Document 3, which will be described later, entitled "Method for Producing a Ruthenium Complex".

(1) A method for producing a ruthenium complex represented by the general formula RuL ₂ (SCN) ₂ .2H ₂ O (L is 2,2'-bipyridine-4,4'-dicarboxylic acid), characterized in that The purified trivalent ruthenium chloride (RuCl ₃ ·3H ₂ O) and the ligand (L: 2,2'-bipyridine-4,4'-dicarboxylic acid) react in an organic solvent by heating to generate RuL ₂ Cl ₂ ·2H ₂ O, then, the obtained reaction product is dissolved in an organic solvent, the dissolved product is reacted with sodium thiocyanate by heating, and the obtained RuL ₂ (SCN) ₂ ·2H ₂ O is treated with The insoluble cross-linked polymer gel filtration carrier was used for purification.

In addition, a preferred embodiment is: (2) The method for producing a ruthenium complex according to (1), characterized in that the gel filtration carrier comprising an insoluble cross-linked polymer having an alcoholic hydroxyl group is made of a hydrophilic polymer Semi-rigid gels and cross-linked agarose gels with methacrylate or polyvinyl alcohol as the main body; (3) the manufacturing method of the ruthenium complex according to (1), characterized in that the heating reaction is performed at 110 to 150 and (4) the method for producing a ruthenium complex according to (1), characterized in that the heating reaction is carried out in the presence of an inert gas and under light-shielding conditions.

Patent Document 1: Specification of US Patent No. 5463057 (Example 1, Example 2);

Patent Document 2: Japanese Patent Laid-Open Publication No. 11-279188 (paragraphs 0004 to 0005);

Patent Document 3: JP-A-2001-139587 (paragraphs 0004 to 0005);

Non-Patent Document 1: P.Liska et al, "cis-Diaquabis(2,2′-bipyridyl-4,4′-dicarboxylate)-ruthenium(II) Sensitizes Wide Band Gap Oxide Semiconductors Very Efficiently overa Broad Spectral Range in the Visible ", J. Am. Chem. Soc. 1988, 110, 3686-3687 (p3686);

Non-Patent Document 2: MK Nazeeruddin et al, "Conversion of Light to Electricity by cis-X ₂ Bis(2,2'-bipyridyl-4,4'-dicarboxylate) ruthenium(II) Charge-Transfer Sensitizers (X=Cl ^- , Br ^- , I ^- , CN ^- , and SCN ^- ) on Nanocrystalline TiO ₂ Electrodes", J.Am.Chem.Soc.1993, 115, 6382-6390 (p6383: Materials);

Non-Patent Document 3: Md.K.Nazeeruddin et al, "Acid-Base Equilibriaof(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium(II) Complexes and the Effect of Protonation on Charge-Transfer Sensitization of Nanocrystalline Titania ", Inorg.Chem.1999, 38, 6298-6305 (p6299: Synthesis of complexes 1, and 2, p6303: HPLC of complex 2)

Contents of the invention

In the techniques described in the above-mentioned patent documents 1, 2, 3 and non-patent documents 2, 3, in the synthesis of (cis-dichloro-bis(2,2'-bipyridine-4,4'-dicarboxylic acid) Ru( _{dcbpy ) 2} Cl ₂ Cl ₂ Cl ₂ Impurities are separated and purified by recrystallization. Next, use the purified Ru(dcbpy) ₂ Cl ₂ to synthesize cis-bis(isothiocyano)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)ruthenium(II) complex compound (Ru(dcbpy) ₂ (NCS) ₂ ).

In the techniques described in Patent Documents 1, 2, and 3 and Non-Patent Documents 2 and 3, since Ru(dcbpy) ₂ Cl ₂ as an intermediate product is separated and purified, it takes a long time to obtain the final product. , the separation and purification of the intermediate product led to a decrease in the yield of the target product Ru(dcbpy) ₂ (NCS) ₂ .

The cost of raw materials such as RuCl ₃ ·3H ₂ O and dcbpy necessary for the synthesis of Ru(dcbpy) ₂ (NCS) ₂ is high, and the waste liquid generated in the synthesis step contains a large amount of heavy metals that are difficult to handle and pollute the environment. If the target Ru(dcbpy) ₂ (NCS) ₂ yield is low, in order to obtain the required amount of Ru(dcbpy) ₂ (NCS) ₂ , it is necessary to increase the amount of raw materials used, and as a result, the waste liquid treatment amount also increased. Therefore, an increase in cost is caused, making it difficult to reduce the production cost of the dye-sensitized solar cell.

In addition, in Patent Documents 1, 2, 3 and Non-Patent Documents 2, 3, there is no mention of the technology of synthesizing Ru(dcbpy) ₂ (NCS) ₂ of the target product without isolating and purifying the intermediate product Ru(dcbpy) ₂ Cl ₂ .

Hereinafter, in the description of the present invention, "crude product" refers to "unpurified product (containing by-products such as isomers other than the target molecule)". "Final product" refers to "a product with a purity of more than 99% after purification by HPLC".

In addition, "crude yield" means "(amount of crude product/theoretical yield) x 100%". "Actual yield" means "(amount of final product/theoretical yield)×100%)". "Theoretical yield" refers to "the amount of the target molecule that should be produced theoretically according to the stoichiometric amount". "Purity" means "(the amount of the target molecule contained in the product/the amount of the product) x 100%. For example, the "purity" can be obtained by HPLC as described below. In addition, it is only expressed as "yield" The occasion refers to the "actual yield".

The present invention is carried out in order to solve the above-mentioned problems, and its object is to provide a short-term, high-yield, high-purity synthesis of cis-bis(isothiocyanato)-bis(2,2'-bipyridine- 4,4'-dicarboxylic acid) ruthenium (II) complex Ru(dcbpy) ₂ (NCS) ₂ production method.

That is to say, the present invention is about the manufacture method of ruthenium complex, comprising: the first step, make ruthenium (III) chloride and 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy) Heating the reaction in a reaction vessel containing a polar organic solvent generates cis-dichloro-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) complex (Ru(dcbpy ) ₂ Cl ₂ ); and the second step, that is, after the first step reaction, to the above-mentioned cis-dichloro-bis(2,2'-bipyridine-4,4'-dicarboxylic acid) ruthenium (II) Add isothiocyanate to the solution in the above-mentioned reaction vessel of the complex, so that the above-mentioned cis-dichloro-two (2,2'-bipyridine-4,4'-dicarboxylic acid) ruthenium ( II) The complex compound and the above-mentioned isothiocyanate are heated and reacted to generate cis-bis(isothiocyanate)-bis(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(II ) complex (Ru(dcbpy) ₂ (NCS) ₂ ).

According to the present invention, due to the synthesis of (cis-dichloro-bis(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(II) complex (Ru(dcbpy) ₂ Cl ₂ )) After (the first step), the separation and purification of Ru(dcbpy) ₂ Cl ₂ are not carried out, but (cis-bis(isothiocyano)-bis(2,2'-bipyridine-4 , 4'-dicarboxylic acid) ruthenium (II) complex (Ru(dcbpy) ₂ (NCS) ₂ ) synthesis (second step), so it can prevent the separation and purification of Ru(dcbpy) ₂ Cl ₂ The resulting problem of low yield, and can shorten the time to obtain the final product.

In addition, for the first and second step reactions, by optimizing the reaction conditions such as the reaction temperature, the amount of by-products such as isomers can be reduced, so that the target Ru can be obtained with high purity, high yield, and low cost. (dcbpy) ₂ (NCS) ₂ .

Description of drawings

Fig. 1 compares and illustrates the difference between the one-pot method in the embodiment of the present invention and the known synthetic method;

Figure 2 is a diagram illustrating the synthetic steps of the one-pot method in an embodiment of the invention;

Fig. 3 is a specific embodiment illustrating the synthetic steps based on the one-pot method in the present invention;

4 is a schematic cross-sectional view illustrating the configuration of a dye-sensitized solar cell to which a sensitizing dye (Ru(dcbpy) ₂ (NCS) ₂ ) synthesized in an embodiment of the present invention is applied;

Fig. 5 is the table of raw materials in the experiment of optimizing the first step reaction condition of the embodiment of the present invention;

Fig. 6 is the experimental result of the optimization first step reaction temperature of the embodiment of the present invention;

Fig. 7 is to the first step reaction temperature in the embodiment of the present invention and the crude product purity of product N3-1 to N3-8, the figure that the relationship between actual yield is explained;

Figure 8 is an HPLC chromatogram of crude products from N3-1 to N3-4 at different first step reaction temperatures in an example of the present invention;

Figure 9 is a diagram illustrating the HPLC chromatograms of the crude products from N3-5 to N3-8 synthesized at different reaction temperatures in the first step in the examples of the present invention;

Figure 10 illustrates the generation of impurities at different first step reaction temperatures in the examples of the present invention;

Fig. 11 is the table of raw materials used in the experiment of optimizing the reaction conditions of the second step in the embodiment of the present invention;

Fig. 12 is the experimental condition of optimizing the second step reaction solvent ratio and reaction temperature in the embodiment of the present invention;

Fig. 13 is aimed at illustrating the relationship between the DMF content in the second step reaction in the embodiment of the present invention, the reaction temperature, and the content of the three coordination isomers;

Fig. 14 is a diagram illustrating the relationship between the reaction temperature in the second step and the amount of tricoordination complex produced in the embodiment of the present invention;

Figure 15 is a diagram illustrating the HPLC chromatograms of crude products from N3-9 to N3-12 at different second-step reaction temperatures in the examples of the present invention;

Fig. 16 is the table of raw materials used in the experiment of optimizing NH ₄ NCS feeding amount in the embodiment of the present invention;

Fig. 17 is the experimental result of NH ₄ NCS feeding amount in the optimization second step reaction in the embodiment of the present invention;

Figure 18 illustrates the relationship between the NH ₄ NCS feed amount in the second-step reaction optimized in the embodiment of the present invention, the crude product purity from N3-13 to N3-15, the actual yield, and the NH ₄ NCS feed amount picture;

Fig. 19 is an HPLC chromatogram of crude products from N3-13 to N3-15 synthesized with different NH ₄ NCS dosages in the examples of the present invention;

Figure 20 is the absorption spectrum of the N3-4 and N3-15 final products synthesized by the one-pot method used in the examples of the present invention;

Fig. 21 is a diagram illustrating the first step reaction and the second step reaction in the known method of the comparative example of the present invention;

Fig. 22 is the first step reaction in the known method of comparative example of the present invention, the raw material table used in the second step reaction; And

Fig. 23 is an HPLC chromatogram of a crude product synthesized by a known method for a comparative example of the present invention.

Detailed ways

In the method for producing a ruthenium complex of the present invention, the temperature of the solution in the reaction container may be cooled to room temperature after the first step reaction. With such a configuration, the amount of by-products such as isomers is reduced, and high-purity target product Ru(dcbpy) ₂ (NCS) ₂ can be obtained.

In addition, it may be configured such that the heating reaction of the first step is performed at 105°C to 120°C, and the heating reaction of the second step is performed at 105°C to 160°C. According to such a constitution, the unreacted 2,2'-bipyridine-4,4'-dicarboxylic acid in the first step performed at 105°C to 120°C, the second step at 105°C to 160°C React with above-mentioned ruthenium(III) chloride in the step, generate above-mentioned cis-dichloro-bis(2,2'-bipyridine-4,4'-dicarboxylic acid) ruthenium(II) complex, the complex compound reacts with the above-mentioned isothiocyanate to generate the above-mentioned cis-bis(isothiocyano)-bis(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(II) complex (Ru(dcbpy) ₂ (NCS) ₂ ), therefore, the amount of by-products such as isomers can be reduced, and high-purity Ru(dcbpy) ₂ (NCS) ₂ can be obtained.

In addition, it may be configured such that the heating reaction in the second step above is performed in a liquid mixture in which the polar organic solvent and water are mixed so that the boiling point thereof is 105°C to 160°C. According to such a constitution, the temperature of the heating reaction of the above-mentioned second step can be controlled by the mixing ratio of the above-mentioned polar organic solvent and water, and the amount of generation of by-products such as isomers can be reduced, and the high-purity target product Ru ( dcbpy) ₂ (NCS) ₂ . For example, the aforementioned polar organic solvent is DMF (dimethyl formamide, dimethylformamide) with a boiling point of 152°C.

In addition, it may be configured such that dimethylformamide is used as the polar organic solvent. With such a configuration, the target product Ru(dcbpy) ₂ (NCS) ₂ can be obtained using a general-purpose organic solvent.

In addition, it may be constituted as follows: a third step is included, that is, after the reaction in the second step above, cis-bis(isothiocyanato)-bis(2,2'- Bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) complex. According to such a constitution, highly pure target product Ru(dcbpy) ₂ (NCS) ₂ can be obtained.

In addition, it may be configured to perform the above-mentioned purification treatment using chromatography. According to such a configuration, separated and purified high-purity Ru(dcbpy) ₂ (NCS) ₂ can be obtained in a short time.

In addition, the above-mentioned isothiocyanate may be added in a stoichiometric ratio of 8 times or more relative to the above-mentioned 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy). According to such a structure, since it adds 8 times or more of the theoretical value of the stoichiometric ratio with respect to the said 2,2'-bipyridine-4,4'-dicarboxylic acid (dcbpy), it is possible to reduce isomer etc. The amount of by-products was reduced, and the target product Ru(dcbpy) ₂ (NCS) ₂ with high purity was obtained.

In addition, the above-mentioned isothiocyanate may be any one of ammonium isothiocyanate, sodium isothiocyanate, and potassium isothiocyanate. According to such a constitution, it is not necessary to limit the isothiocyanate to the designated isothiocyanate.

The production method of the ruthenium complex of the present invention is such a production method: that is, including the first step and the second step, wherein the first step synthesizes Ru(dcbpy) ₂ Cl ₂ as an intermediate product, and the second step synthesizes Ru( dcbpy) ₂ (NCS) ₂ , and after Ru(dcbpy) _{2 Cl 2 is synthesized, Ru(dcbpy) 2 Cl 2 is not} separated and purified, so that the first step and the second step are carried out in the same reaction vessel Pot synthesis (one-pot synthesis, hereinafter sometimes referred to as one-pot method).

Ru(dcbpy) ₂ (NCS) ₂ can be synthesized by simple operation because Ru(dcbpy) ₂ Cl ₂ as an intermediate product is not isolated and purified in the one-pot method. The time required for the separation and purification of the intermediate product is saved, and the reduction of the yield caused by the separation and purification of the intermediate product is avoided. For the first and second steps of the one-pot method, the overall synthesis time can be shortened by optimizing the reaction conditions such as the reaction temperature and the composition ratio of the reaction mixture.

By making the reaction temperature of the first step at 105° C. to 120° C., more preferably at 105° C. to 116° C., the synthesis of Ru(dcbpy) ₂ Cl ₂ as an intermediate product can be fully carried out, and the reaction temperature of the first step is 170° C. The purity of the crude product of Ru(dcbpy) ₂ (NCS) ₂ , which is the target molecule, can be increased by about 2 times or more compared to the case of 180°C to 180°C. If the reaction temperature in the first step exceeds 120°C, by-products other than the target molecule are obviously formed as precipitates, so it is more preferable that the reaction temperature in the first step is not higher than 116°C, the temperature at which the by-products start to precipitate.

In addition, the reaction temperature of the second step is set at 150°C to 160°C, and the NH ₄ NCS added in the second step reaction is excessive, that is, 8 times the theoretical value of the stoichiometric ratio relative to dcbpy. The formation of by-products such as isomers can increase the purity of the crude product of Ru(dcbpy) ₂ (NCS) ₂ , which is the target molecule, about twice compared to the case of adding NH ₄ NCS in the same mole number as dcbpy.

Although a reaction by-product was formed during the synthesis of Ru(dcbpy) ₂ (NCS) ₂ as the target product, in the one-pot method, by optimizing the first step and the second step of each synthesis in the one-pot method The reaction conditions of the reaction can suppress the formation of isomers, and can obtain Ru(dcbpy) ₂ (NCS) ₂ as the target product with high yield, high purity and low cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(implementation mode)

In the following descriptions, including the figures, "dcbpy" or "L" indicates the term 2,2'-bipyridyl-4,4'-dicarboxylic acid (2,2'-bipyridyl-4,4'- dicarboxylic acid) or 4,4'-dicarboxy-2,2'-bipyridine (4,4'-dicarboxyl-2,2'-bipyridine) ligand.

First, an overview of the one-pot method according to an embodiment of the present invention and a comparison between the one-pot method and a synthesis method based on a known method will be described.

(Comparison of one-pot-based synthesis of Ru(dcbpy) ₂ (NCS) ₂ with known methods-based synthesis)

Fig. 1 compares and illustrates the difference between the one-pot method and the known synthetic method in the embodiment of the present invention, Fig. 1 (A) is a one-pot method, and Fig. 1 (B) is to illustrate for known method, Fig. 1 (C ) indicates the structures of the compounds involved in the reaction.

Figure 2 is a diagram illustrating the steps of a one-pot synthesis in an embodiment of the invention.

As shown in Fig. 1(A) and Fig. 2, the one-pot method includes the first step reaction and the second step reaction carried out in the same reaction vessel. The stoichiometric ratio involved in the overall reaction of the first step and the second step is: RuCl ₃ : dcbpy: Ru(dcbpy) ₂ Cl ₂ : NH ₄ NCS: Ru(dcbpy) ₂ (NCS) ₂ = 1:2:1 :2:1.

In the first step, Ru(dcbpy) ₂ (NCS) ₂ is dissolved dcbpy and RuCl ₃ (Ruthenium(III) trichloride, ruthenium trichloride) in DMF (solvent) (dimethyl formamide, dimethylformamide) , under the protection of light-proof conditions and inert gas (rare gas or nitrogen (N ₂ )), the solvent is refluxed, and the reaction is carried out at a predetermined temperature such as 105°C to 120°C for at least 6 hours, and Ru(dcbpy) ₂ Cl ₂ (cis -dichloro-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium(II) complex, cis-dichloro-bis(2,2'-bipyridine-4,4'-dicarboxylic acid) Synthetic reaction of ruthenium (II) complex).

In the second step reaction, Ru(dcbpy) ₂ Cl ₂ and NH ₄ NCS (ammonium isothiocyanate, ammonium isothiocyanate) were dissolved in DMF aqueous solution (DMF and water In a mixed solvent), the solvent is refluxed under light-shielding conditions and an atmosphere of an inert gas (rare gas or nitrogen (N ₂ )), and the reaction is carried out at a predetermined temperature such as 105° C. to 160° C. for at least 4 hours to perform Ru (dcbpy) ₂ (NCS) ₂ (cis-di(isothiocyanato)-bis(2,2′-bipyridyl-4,4′-dicarboxylic acid)ruthenium(II) complex, cis-di(isothiocyanato)-bis(2, 2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) complex) synthesis reaction. In addition, the predetermined temperature is controlled by the content ratio (volume ratio) of DMF in the DMF aqueous solution (mixed solvent of DMF and water).

The reactions surrounded by a thick line shown in Fig. 1(A) were carried out in a single reaction vessel. In the one-pot method, the Ru(dcbpy) ₂ Cl ₂ generated in the first step reaction is not separated and purified, and the second step reaction is directly performed to recover the final Ru(dcbpy) ₂ (NCS) ₂ , Separation and purification.

As shown in Fig. 1 (B), in the synthetic method based on known method, although carry out the first step and the same synthetic reaction of the second step of the one-pot method shown in Fig. 1 (A), however, in the After the Ru(dcbpy) ₂ Cl ₂ generated in the first step reaction is separated and purified, the second step is performed to recover, separate and purify the finally generated Ru(dcbpy) ₂ (NCS) ₂ .

As shown by the thick line shown in FIG. 1(B), in the synthesis method based on the known, the first-step and second-step reactions are performed in different reaction vessels. Among the syntheses based on known methods, there is a disadvantage of a decrease in the yield due to the isolation and purification of the intermediate Ru(dcbpy) ₂ Cl ₂ .

In the one-pot method shown in Fig. 1(A) and Fig. 2, the synthesis reaction of the first step is preferably a heating reaction carried out at 105°C to 120°C, and the synthesis reaction of the second step is at 105°C to 160°C The heating reaction carried out. In addition, it is preferable to separate and purify finally produced Ru(dcbpy) ₂ (NCS) ₂ using chromatography. In addition, as the organic solvent used in the first-step and second-step synthesis reactions, DMF can be used.

In addition, as the isothiocyanate used in the second-step reaction, sodium isothiocyanate (NaCNS, sodium isothiocyanate) and potassium isothiocyanate (KCNS, potassium isothiocyanate) can be used in addition to NH ₄ NCS , it is preferable that the amount of isothiocyanate added is 8 times or more the theoretical value of the stoichiometric ratio relative to dcbpy.

Figure 3 is an embodiment illustrating the one-pot-based synthetic steps in the present invention.

(Synthesis of the first step Ru(dcbpy) ₂ Cl ₂ )

As shown in Figure 3(1), in the first step of the one-pot method, DMF (solvent) and RuCl ₃ 3H ₂ O were added to a three-necked flask including a condenser tube to make RuCl ₃ 3H ₂ O Dissolve (step (1-1)), and add dcbpy (step (1-2)). Next, the solvent is refluxed under light-shielding conditions and an inert gas atmosphere, and reacted at a predetermined temperature such as 105° C. to 120° C. for a predetermined time such as 8 hours to generate Ru(dcbpy) ₂ Cl ₂ (step (1-3)), Cool (steps (1-4)).

(The second step is the synthesis of Ru(dcbpy) ₂ (NCS) ₂ )

As shown in Figure 3(2), in the second step, NH ₄ NCS aqueous solution is added to the solution in the three-necked flask containing Ru(dcbpy) ₂ Cl ₂ synthesized by the first step (step (2- 1)). Next, the solvent is refluxed under light-shielding conditions and an inert gas atmosphere, and reacted at a predetermined temperature such as 105° C. to 160° C. for a predetermined time such as 4 hours to generate Ru(dcbpy) ₂ (NCS) ₂ (step (2-2) ).

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

According to the steps (2-3) to (2-11) described below, from the solution containing Ru(dcbpy) ₂ (NCS) ₂ synthesized by the second step, from the solution in the three-necked flask, separate and purify Ru( dcbpy) ₂ (NCS) ₂ .

After step (2-2) finishes, with reaction solution cooling (step (2-3)), the solution in the three-necked flask that contains Ru(dcbpy) ₂ (NCS) removes solvent with rotary evaporator (step ( ₂ ) -4)). The residue generated by step (2-4) was dissolved in NaOH aqueous solution (step (2-5)), and filtered (step (2-6)). Add HNO ₃ to the filtrate in step (2-6), adjust to pH = 3.5, and precipitate the solid phase (containing Ru(dcbpy) ₂ (NCS) ₂ ) (step (2-7)), then, Store overnight in the library (or refrigerator) (steps (2-8)).

Next, it was taken out from the freezer, the solid (containing Ru(dcbpy) ₂ (NCS) ₂ ) was collected by filtration (step (2-9)), and the solid was dried in a vacuum desiccator (step (2-10)). Finally, preparative HPLC (high performance liquid chromatography, high performance liquid chromatography) was used to obtain purified Ru(dcbpy) ₂ (NCS) ₂ ) (step (2-11)).

(difference between one-pot and known method-based synthesis)

In the synthesis method based on a known method, after the first step reaction (synthesis of Ru(dcbpy) ₂ Cl ₂ ), filtration treatment and recrystallization treatment are performed to purify Ru(dcbpy) ₂ Cl ₂ , but in the present invention In the one-pot method of , these steps for purification were omitted. The one-pot method has at least the following three advantages.

(1) Since Ru(dcbpy) ₂ Cl ₂ as an intermediate product is not subjected to separation and purification treatment, there will be no decrease in yield due to separation and purification treatment.

(2) After all the synthesis reactions are finished, due to the absence of the target product and monoligand complexes and triligand complexes of dcbpy, the loss of by-products (impurities) such as trans-isomers and S-isomers , so analysis with HPLC (high performance liquid chromatography) can faithfully reflect the purity of the crude product. In this way, the purity of the crude product can be improved by changing different reaction conditions or feed ratios, thereby increasing the actual output.

(3) The entire synthesis based on the one-pot method can be completed within 3 days, while the synthesis method based on a known method requires more than 1 week. Shortening the synthesis time is beneficial to reduce the manufacturing cost.

Ru(dcbpy) ₂ (NCS) ₂ synthesized as described above can be applied to dye-sensitized photoelectric conversion devices, typically, dye-sensitized solar cells.

(Example of a device using synthesized Ru(dcbpy) ₂ (NCS) ₂ )

4 is a schematic cross-sectional view illustrating the configuration of a dye-sensitized solar cell to which a sensitizing dye (Ru(dcbpy) ₂ (NCS) ₂ ) synthesized in an embodiment of the present invention is applied.

A brief description will be given of a dye-sensitized solar cell (DSSC). The DSSC includes: a photoelectrode disposed on the incident side of sunlight 11 , a counter electrode opposed thereto, and an electrolytic solution 16 held between the two electrodes. The photoelectrode is formed by a photoelectrode-side transparent conductive film 13 on the photoelectrode-side transparent substrate 12, and a nanometer-sized titanium oxide (TiO ₂ ) semiconductor porous film 14 carrying a sensitizing dye is arranged on the photoelectrode-side transparent conductive film 13 . Sensitizing dyes such as ruthenium bipyridine complexes. The counter electrode is formed by the counter electrode side conductive film 17 formed on the counter electrode side substrate 18 , and an electrolyte solution injection hole (not shown) is formed in the counter electrode side substrate 18 .

The two electrodes (the photoelectrode comprising the photoelectrode side transparent conductive film 13 and the photoelectrode side transparent substrate 12, the counter electrode comprising the counter electrode side conductive film 17 and the counter electrode side substrate 18) are joined by a sealing material 15, formed on the counter electrode After the electrolytic solution 16 is injected between the two electrodes through the electrolytic solution injection hole (not shown) on the side substrate 18 , the electrolytic solution injection hole is sealed.

In this way, an electrolytic solution 16 composed of a redox system such as I ⁻ and I ₃ ⁻ dissolved in a nitrile solvent is held between the photoelectrode side transparent conductive film 13 and the counter electrode side conductive film 17 .

Once sunlight 11 irradiates the photoelectrode of the DSSC, the ground state electrons of the sensitizing dye are excited and migrate to the excited state, and the excited state electrons are transferred to the valence band of titanium dioxide, injected into the conduction band of the titanium oxide semiconductor, and reach the photoelectrode.

In addition, the sensitizing dye that has lost electrons accepts electrons from a reducing agent (such as iodide ion I ^- ) in the electrolyte solution by the following reaction,

An oxidizing agent such as triiodide ion I ₃ ⁻ (combination of I ₂ and I ⁻ ) is generated in the electrolyte solution. The generated oxidant reaches the counter electrode by diffusion, accepts electrons from the counter electrode through the reverse reaction of the above reaction,

is reduced to the original reducing agent.

The electrons sent from the transparent conductive layer to the external circuit return to the counter electrode after the external circuit performs electric work. In this way, light energy is converted into electrical energy, leaving neither any change in the sensitizing dye nor any change in the electrolyte solution. By repeating such a process, light is converted into electric current, and electric energy is output to the outside.

As the photoelectrode-side transparent substrate 12, transparent inorganic substrates such as quartz, sapphire, and glass, and polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polyphenylene sulfide, etc., can be used. Transparent plastic substrates such as polyvinylidene fluoride, polyimide, polysulfone, polyolefin, etc. They can also be used as the counter electrode side substrate 18 .

As the photoelectrode-side transparent conductive film 13, for example, indium tin composite oxide (ITO), fluorine-doped SnO ₂ (FTO), antimony-doped SnO ₂ (ATO), SnO ₂ and the like can be used.

The semiconductor material constituting the semiconductor porous film 14 is preferably an n-type semiconductor material that conduction band electrons become carriers under photoexcitation and generates anodic current, preferably anatase-type titanium oxide TiO ₂ , or Using other materials such as MgO, ZnO, SnO ₂ , WO ₃ , Fe ₂ O ₃ , In ₂ O ₃ , Bi ₂ O ₃ , Nb ₂ O ₅ , SrTiO ₃ , BaTiO ₃ , ZnS, CdS, CdSe, CdTe, PbS , CuInS, InP, etc.

As a sensitizing dye supported on semiconductor fine particles, the Ru bipyridine complex synthesized by the present invention is preferably used because of its high quantum yield.

The electrolyte solution 16 is obtained by dissolving a redox system (redox couple) in a solvent, wherein the redox system (redox couple) causes at least one reversible oxidation/reduction state change. For example, redox couples can be halogens such as I ⁻ /I ₃ ^- and Br ⁻ /Br ₂ , quinones/hydroquinones, pseudohalogens such as SCN ⁻ /(SCN) ₂ , iron(II) ions/iron(III) ions, copper(I) ions/copper(II) ions, etc.

More specifically, as the electrolyte, for example, a combination of iodine (I ₂ ) and a metal iodide or an organic iodide, or a combination of bromine (Br ₂ ) and a metal bromide or an organic bromide can be used. The cations constituting metal halide salts can be Li ⁺ , Na ⁺ , K ⁺ , Cs ⁺ , Mg ²⁺ , Ca ²⁺ , etc. The cations constituting organic halide salts are preferably tetraalkylammonium ions and pyridinium ions , imidazolium ions and other quaternary ammonium ions.

In addition, as electrolytes, a combination of ferrocyanate and ferricyanide, a combination of ferrocene and Fe(C ₅ H ₅ ) ₂ ⁺ ions, sodium polysulfide or alkylthiol and alkylated disulfide can be used combinations etc. Among them, an electrolyte obtained by combining iodine (I ₂ ) with an imidazole compound such as lithium iodide (LiI), sodium iodide (NaI), or imidazole iodide is preferable.

As the solvent for the electrolytic solution 16, for example, nitriles such as acetonitrile, carbonates such as propylene carbonate and ethylene carbonate, γ-butyrolactone, pyridine, dimethylacetamide, and other polar solvents can be used. , methyl propyl imidazolium iodide (MPII) and other ionic solutions or their mixtures.

In addition, in order to prevent electron recombination in the electrolyte solution, additives can also be added to increase the open circuit voltage or short circuit current. As these additives, tert-butylpyridine, 1-methoxybenzimidazole, long-chain alkyl group-containing carboxylic acids, and the like can be used.

The counter electrode-side conductive film 17 is preferably electrochemically stable, and for example, platinum, gold, carbon, conductive polymers, and the like can be used.

(Example)

In order to increase the crude product purity and actual yield of Ru(dcbpy) ₂ (NCS) ₂ as the target molecule (hereinafter referred to as the target molecule), it is crucial to suppress the single-unit of dcbpy contained in the final product synthesized by the one-pot method. Formation of by-products (impurities) such as coordination complexes and three-coordination complexes, trans isomers, and S-isomers.

Study the optimal reaction conditions related to the first step reaction (synthesis of Ru(dcbpy) ₂ Cl ₂ ) and the second step reaction (synthesis of Ru(dcbpy) ₂ (NCS) ₂ ) in the one-pot method, synthesize Ru(dcbpy) ₂ (NCS) ₂ .

(General matter in experiments looking for optimal reaction conditions for a one-pot method)

First, general reaction conditions in experiments for finding optimal reaction conditions for the first-step reaction and the second-step reaction of the one-pot method will be described.

(Synthesis of the first step Ru(dcbpy) ₂ Cl ₂ )

Dissolve RuCl ₃ 3H ₂ O in 100 mL of DMF (solvent) and put into a round-bottomed flask, wrap the round-bottomed three-necked flask with aluminum foil, and stir the solution for 15 minutes in the dark and Ar gas atmosphere, and then pour into the solution Add dcbpy in, reflux in the dark and Ar gas atmosphere, and heat for 8 hours.

(The second step is the synthesis of Ru(dcbpy) ₂ (NCS) ₂ )

After the first step of reaction, the solution in the round-bottomed three-necked flask was cooled to room temperature, then NH ₄ NCS was added into the round-bottomed three-necked flask, and refluxed for 4 hours in the dark and Ar gas atmosphere.

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

After the second step reaction, cool the solution in the round-bottomed three-necked flask to room temperature, use a rotary evaporator to remove the solvent, and dissolve the residue in the round-bottomed three-necked flask in the solution (0.5MNaOH 10mL+H ₂ O 20mL) , and filter the solution through a filter funnel.

1M HNO ₃ was added to the filtered solution to adjust the pH to 1.7, and a solid (complex) was precipitated. Then, put it into a freezer (-17.5° C.) overnight to fully precipitate the solid. The solid was recovered on a filter funnel and dried in a vacuum desiccator to give crude product.

Next, an experiment to find the optimum reaction temperature in the first step will be described.

(Optimization of the reaction temperature of the first step reaction (synthesis of Ru(dcbpy) ₂ Cl ₂ ))

(first step (synthesis of Ru(dcbpy) ₂ Cl ₂ ))

RuCl ₃ 3H ₂ O dissolved in DMF (solvent) 100mL was added to a round-bottomed three-necked flask, and the round-bottomed three-necked flask was wrapped with aluminum foil, and in a dark and Ar gas atmosphere, the solution was stirred for 15 minutes, and then added to the Add dcbpy to the solution, and heat the solvent to reflux for 8 hours in the dark and Ar gas atmosphere. The heating temperature of the solvent is set to different temperatures, and the first step reaction is carried out at different reaction temperatures ranging from low temperature to high temperature.

The second-stage reaction performed after the first-stage reaction and the treatment performed thereafter are as follows.

(Second step (synthesis of Ru(dcbpy) ₂ (NCS) ₂ ))

After the first step of the reaction, the solution in the round-bottomed three-necked flask was cooled to room temperature, after which _NH4NCS dissolved in 30 mL of _H2O was added to the round-bottomed three-necked flask, and in the dark, Ar gas atmosphere , reflux at 110°C for 4 hours.

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

After the second step reaction, cool the solution in the round-bottomed three-necked flask to room temperature, use a rotary evaporator to remove the solvent, and dissolve the residue in the round-bottomed three-necked flask in the solution (0.5MNaOH 10mL+H ₂ O 20mL) , and filter the solution through a filter funnel. Next, 1M HNO ₃ was added to the filtered solution to adjust the pH to 1.7, and a solid (complex) was precipitated. Further, it was placed in a refrigerator (-17.5° C.) overnight to fully precipitate the solid. The solid was recovered on a filter funnel and dried in a vacuum desiccator to give crude product.

The crude product was purified using preparative HPLC (High Performance Liquid Chromatography) to give the final product.

Fig. 5 is a table of raw materials in the experiment of optimizing the reaction conditions of the first step in the embodiment of the present invention.

As shown in FIG. 5 , the addition amount of dcbpy was set to the theoretical value of the stoichiometric ratio of RuCl ₃ ·3H ₂ O, and NH ₄ NCS was added at 1.2 times the theoretical value of the stoichiometric ratio of dcbpy.

Fig. 6 is the experimental result of optimizing the reaction temperature of the first step in the embodiment of the present invention, showing the reaction temperature, the purity of the crude product of Ru(dcbpy) ₂ (NCS) ₂ and the actual yield. In FIG. 6 , the purity of the crude product represents the value obtained by HPLC, and the actual yield represents the value considering the purity obtained by HPLC.

In addition, N3-i (i=1 to 15) shown in FIG. 6, FIG. 8, FIG. 9, FIG. 12, FIG. 15, and FIG. (dcbpy) ₂ (NCS) ₂ ".

7 is a diagram illustrating the relationship between the first step reaction temperature and the crude product purity and actual yield of products N3-1 to N3-8 in an embodiment of the present invention, and is a graph of FIG. 6 .

In Fig. 7, the horizontal axis represents the reaction temperature of the first step, the vertical axis on the left represents the purity of the crude product, and the vertical axis on the right represents the actual yield. As shown in Figure 7, the purity and actual yield of the crude product decreased approximately proportionally with the increase of the reaction temperature, and the lower the reaction temperature in the first step, the higher the purity of the crude product.

For example, when the reaction temperature is low temperature of 124°C, 92°C and 50°C, the actual yield increases greatly, which are 3.60 times, 5.00 times and 9.45 times of the actual yield when the reaction temperature is 178°C, respectively. Moreover, by reducing the reaction temperature from 178°C to 50°C, the purity of the crude product increased approximately 2.7 times.

Fig. 8 is an HPLC chromatogram of crude products from N3-1 to N3-4 at different reaction temperatures of the first step in an example of the present invention.

Fig. 9 is a diagram illustrating HPLC chromatograms of crude products from N3-5 to N3-8 synthesized at different reaction temperatures in the first step in the examples of the present invention.

In Figure 8 and Figure 9, the horizontal axis represents the dissolution time (min), the vertical axis represents the intensity (arbitrary scale (scale)), and the reaction temperature, generated impurities and crude product purity are annotated on the HPLC chromatogram.

As shown in Figures 7 and 8, the HPLC chromatograms include the cis-formisomer (cis-formisomer) of the target molecule Ru(dcbpy) ₂ (NCS) ₂ (dcbpy's two-coordination complex). The main peak is derived from the peak of impurity 1 (tri-ligand complex of dcbpy), and the trans-isomer (trans-form isomer) of impurity 2 (two coordination complex of dcbpy), respectively )), impurity 3 (S-form isomer (S-form isomer) of the two-coordination complex of dcbpy), and peaks of impurity 4 (mono-ligand complex (mono-ligand complex) of dcbpy). The positions of these peaks are indicated by dotted lines, and are similarly indicated in FIGS. 15 , 19 and 23 to be described later.

In addition, the HPLC chromatograms shown in Fig. 7, Fig. 8 and Fig. 15, Fig. 19 and Fig. 23 described later are obtained by plotting chromatograms of different samples and displaying them on the same time axis. Since the traces include deviations when they are created, they are not used for strict comparison of peak positions in chromatograms, but are used for relative comparisons of peak intensities in chromatograms between different samples.

As shown in Figures 7 and 8, at a reaction temperature exceeding 124°C, the key factor determining the yield of the crude product is the tricoordinate complex contained in the crude product. The three-coordination complex is significantly reduced at a low reaction temperature of 124°C or less. In addition, when the reaction temperature is between 120°C and 105°C, no tricoordinate complex is formed.

When the reaction temperature is lower than 105°C, a precipitate different from a three-coordination complex is formed. The tricoordinate complex is dark red and the different precipitate is reddish, almost pink. This is due to the color of the raw material dcbpy due to the low solubility of dcbpy relative to DMF (dimethylformamide). It can be concluded that at the low reaction temperature below 105 °C, the synthesis reaction of the first step is not completed. The HPLC chromatograms obtained at reaction temperatures ranging from 105°C to 50°C were almost identical, and the ratios of the respective impurities were also similar.

This result shows that in the second step, Cl in Ru(dcbpy) ₂ Cl ₂ is replaced not only by NCS but also by dcbpy. Under the reaction conditions of the second step, the equilibrium among dcbpy, Ru(dcbpy) ₂ Cl ₂ and Ru(dcbpy) ₂ (NCS) ₂ shifted towards the target molecule Ru(dcbpy) ₂ (NCS) ₂ .

In the first reaction of the synthesis based on known methods, preferably at a reaction temperature between 120° C. and 105° C., the synthesis reaction is complete with minimal formation of tricoordinate complexes. In contrast, the reaction temperature of the first step of the one-pot method is more preferably between 120° C. and 50° C., and the unfinished reaction in the first step at a lower reaction temperature is completed in the second step.

In Non-Patent Document 3, the reaction temperature of the first step is set at 179°C to 180°C. In order to increase the yield and purity of Ru(dcbpy) ₂ (NCS) ₂ , it is preferable to set the reaction temperature at 105°C as described above. The reaction was carried out at 120°C.

Items related to the reaction temperature and the progress of the reaction in the first step of the one-pot method described above, the generation of impurities contained in the final product, and the evaluation of the reaction temperature in the first step are summarized in the following figure 10 is shown.

FIG. 10 illustrates the generation of impurities at different reaction temperatures in the first step in the examples of the present invention.

As shown in FIG. 10 , at the reaction temperature of the first step higher than 120° C., the synthesis reaction proceeds excessively and an impurity tricoordinate complex is formed, so the reaction temperature is not suitable.

At the reaction temperature of the first step of 105° C. to 120° C., the synthesis reaction proceeds moderately and the generation of impurities is suppressed, which is also suitable for the second step reaction.

At the reaction temperature of the first step of 50 °C to 105 °C, the progress of the synthesis reaction was incomplete, and unreacted dcbpy remained, but these unreacted dcbpy reacted with _RuCl3 at a temperature above 105 °C of the second step , to generate Ru(dcbpy) ₂ Cl ₂ , Ru(dcbpy) ₂ Cl ₂ reacts with isothiocyanate to generate Ru(dcbpy) ₂ (NCS) ₂ , so the reaction temperature is appropriate.

The above are the experimental results for finding the optimum reaction temperature of the first step.

Next, an experiment to find the optimal reaction conditions of the second step in the one-pot method (the reaction temperature of the second step and the amount of NH ₄ NCS used in the second step) will be described.

(Optimization of the reaction conditions of the second step reaction (synthesis of Ru(dcbpy) ₂ (NCS) ₂ )))

According to the setting conditions of the reaction temperature of the first step, a large amount of three-coordination complex impurities may be generated, and the reaction temperature of the first step is very important for the purity of the crude product and the actual yield. In addition, depending on the reaction conditions in the second step, various isomers may be formed.

The production amount of these isomers is a decisive factor related to the purity of the final product (synthetic sample), and determines the actual yield and production cost. Therefore, suppressing the generation of impurities in the second step reaction is as important as in the first step reaction.

(Optimization of the reaction temperature in the second step)

(first step (synthesis of Ru(dcbpy) ₂ Cl ₂ ))

Dissolve RuCl ₃ 3H ₂ O in 100 mL of DMF (solvent), put into a three-necked flask with a thermometer, wrap the three-necked flask with aluminum foil, and stir the solution for 15 minutes in the dark and Ar gas atmosphere, and then Add dcbpy to the solution, and heat at 116° C. for 8 hours in an Ar gas atmosphere protected from light.

(Second step (synthesis of Ru(dcbpy) ₂ (NCS) ₂ ))

After the first step reaction, the solution in the three-necked flask was cooled to room temperature. NH ₄ NCS and H ₂ O were further added to prepare a reaction system based on a mixed solvent (DMF aqueous solution). By changing the amount of H ₂ O added, reaction systems with different content ratios of DMF in the mixed solvent can be made.

The reaction system was refluxed and stirred for 4 hours in an Ar gas atmosphere protected from light. The reflux temperature (second step reaction temperature) of this reaction system is controlled according to the content ratio of the DMF in the DMF aqueous solution (the mixed solvent of DMF and water).

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

After the reaction in the second step, the solution in the three-necked flask was cooled to room temperature, the solvent was removed using a rotary evaporator, and the solution (5mL 0.5MNaOH+10mL H ₂ O) was added to the residue in the three-necked flask, treated with ultrasonic The solution was left for 10 minutes.

Next, the solution was filtered with a filter funnel, 1M HNO ₃ was added to the filtered solution to adjust its acidity to pH=1.7, and a solid was precipitated.

Next, it was placed in a freezer (-17.5° C.) overnight to fully precipitate the solid. The solid was recovered on a Buchner funnel (suction filter funnel) and dried in a vacuum desiccator to give the crude product.

Fig. 11 is a table of raw materials used in the experiment of optimizing the reaction conditions of the second step in the embodiment of the present invention.

As shown in Figure 11, the amount of dcbpy added was 2.05 times the theoretical value of the stoichiometric ratio of RuCl ₃ 3H ₂ O, and the amount of NH ₄ NCS added was 2.9 times the theoretical value of the stoichiometric ratio of dcbpy times.

Fig. 12 is the experimental condition for optimizing the solvent ratio and reaction temperature in the second step reaction in the embodiment of the present invention.

Fig. 13 is a graph showing the relationship between DMF content, reaction temperature and tricoordinate isomer content in the second step reaction in the embodiment of the present invention, and is a graph of Fig. 12 .

FIG. 14 is a graph illustrating the relationship between the reaction temperature in the second step and the amount of tricoordinate complex produced in the examples of the present invention, and is a graph recurved from FIG. 13 .

As shown in Figure 14, at low temperatures from 105°C to 125°C, the formation of tricoordinate complexes is small, and above 106°C, the formation of tricoordinate complexes increases roughly in proportion to the reaction temperature .

Fig. 15 is a diagram illustrating the HPLC chromatograms of crude products from N3-9 to N3-12 at different reaction temperatures in the second step in the examples of the present invention. In FIG. 15 , the horizontal axis represents dissolution time (min), and the vertical axis represents intensity (arbitrary scale).

The second step reaction temperature is controlled according to the content ratio (volume ratio) of DMF in the DMF aqueous solution (the mixed solvent of DMF and water), is the temperature shown in Fig. 12. In addition, the solvent for the synthesis of N3-9 is pure DMF.

In the HPLC chromatogram shown in Figure 15, the second step reaction temperature and the content ratio (volume ratio) of DMF in the mixed solvent are marked. The sample indicated as commercial in FIG. 15 is an HPLC chromatogram of a commercial product (model Ru535) purchased from Solaronix, and contains a small amount of isomers.

The four HPLC chromatograms of N3-9 to N3-12 shown in FIG. 15 are correlated with the reaction system composed of mixed solvents with different compositions and the reflux temperature. The larger the proportion of DMF in the mixed solvent, the higher the reflux temperature, and the less the amount of trans isomer (impurity 2) generated.

The amount of trans isomers produced in the 100% DMF reaction system was the least, which was even less than that in commercially available products purified by Sephadex ^TM LH-20 column chromatography.

As shown in Figure 15, as the content ratio of DMF in the mixed solvent increases and the reflux temperature increases, the amount of generation of the trans isomer (impurity 2) decreases, but the three-coordinate complex (impurity 1) Generated increased again.

As shown in Figure 14, if the second step reaction temperature rises at 102°C, 106°C, 119°C and 152°C, the peak ratio in the HPLC chromatogram (peak height of the three-coordination complex (impurity 1)/target The peak height of the molecule) changes with 0.3, 0.09, 0.12 and 0.23. When the reaction temperature increases, the generation amount of the three-coordinate complex (impurity 1) first decreases and then increases.

In addition, the peak ratio (peak height of the trans isomer (impurity 2)/peak height of the target molecule) was changed to 0.34, 0.15, 0.12, and 0.07, and the amount of generation of the trans isomer (impurity 2) decreased.

In order to improve the purity of the crude product of the target molecule Ru(dcbpy) ₂ (NCS) ₂ , it is necessary to suppress the conversion of the two-coordinate complex to the three-coordinate complex in the second step reaction.

(optimization of NH ₄ NCS amount in the second step)

As will be described later, the amount of NH ₄ NCS used is a decisive factor for the content of the tricoordinate complex (impurity 1) in the crude product. In the synthesis method not based on the one-pot method but based on the prior art, the amount of NH ₄ NCS added is about 18 times (Non-Patent Document 3) and about 5 times the stoichiometric ratio of Ru(dcbpy) ₂ Cl ₂ (Non-Patent Document 2, Non-Patent Documents 1, 2, 3). In this patent, a study on the amount of NH ₄ NCS used in the one-pot-based synthesis was conducted.

(first step (synthesis of Ru(dcbpy) ₂ Cl ₂ ))

Dissolve in DMF (solvent) 100mL, pack in the three-necked flask with thermometer, the three-necked flask is wrapped with aluminum foil, after the solution is stirred for 15 minutes in dark and Ar gas atmosphere, add dcbpy in the solution, in Protected from light, heated at 116° C. for 8 hours in an Ar gas atmosphere.

(Second step (synthesis of Ru(dcbpy) ₂ (NCS) ₂ ))

After the reaction in the first step, the solution in the three-necked flask was cooled to room temperature, and solvents DMF and NH ₄ NCS were added to the three-necked flask.

For different reactions, add different amounts of NH ₄ NCS. The reaction system was refluxed and stirred at 152° C. (corresponding to the boiling point of the solvent DMF) for 4 hours under protection from light and Ar gas.

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

After the second reaction, the solution in the three-necked flask was cooled to room temperature, and the solvent was removed using a rotary evaporator, and the solution (10mL 0.5MNaOH+20mL H ₂ O) was added to the residue in the three-necked flask, and the solution was ultrasonically treated. solution for 10 minutes.

Next, the solution was filtered with a filter funnel, 1M HNO ₃ was added to the filtered solution to adjust the pH to 1.7, and a solid was precipitated.

Next, it was placed in a freezer (-17.5° C.) overnight to fully precipitate the solid. The solid was recovered on a Buchner funnel (suction filter funnel) and dried in a vacuum desiccator to give the crude product. The crude product was purified by preparative HPLC to give the final product.

Fig. 16 is a table of raw materials used in the experiment of optimizing the NH ₄ NCS feeding amount in the embodiment of the present invention. In addition, the numerical values concerning NH ₄ NCS in FIG. 16 represent theoretical values.

As shown in FIG. 16 , the addition amount of dcbpy was made 2.05 times the theoretical value of the stoichiometric ratio of RuCl ₃ 3H ₂ O, and NH ₄ was added in the same amount as the theoretical value of the stoichiometric ratio of dcbpy NCS. Based on the composition of the raw materials shown in Figure 16, as shown in Figure 17, the theoretical value of the stoichiometric ratio of NH ₄ NCS to dcbpy is slightly less, slightly more, and far too large. The effect of the amount of NH ₄ NCS added on the yield was investigated.

Fig. 17 is the experimental result of the NH ₄ NCS feeding amount in the optimization second step reaction in the embodiment of the present invention, has shown the NH ₄ NCS feeding amount in the reaction solution (theoretical value with respect to the stoichiometric ratio of dcbpy Indicated by reference), the crude product purity of Ru(dcbpy) ₂ (NCS) ₂ , and the actual yield. In FIG. 17 , the purity of the crude product is calculated using HPLC, which means (the amount of the target molecule contained in the crude product/the amount of the crude product)×100%. Actual yield represents (amount of final product/theoretical yield)×100%.

Fig. 18 is a diagram illustrating the relationship between the purity of the crude product, the actual yield and the NH ₄ NCS feeding amount of the second step reaction N3-13 to N3-15 in the embodiment of the present invention, which is the curve of Fig. 17 picture. In FIG. 18 , the horizontal axis represents the amount of NH ₄ NCS (excess amount) in the reaction solution, the vertical axis on the left represents the purity of the crude product, and the vertical axis on the right represents the actual yield.

Fig. 19 is an HPLC chromatogram of crude products from N3-13 to N3-15 synthesized with different NH ₄ NCS dosages in the examples of the present invention. In Fig. 19, the horizontal axis represents the dissolution time (min), the vertical axis represents the intensity (arbitrary scale), and the purity of the crude product and the impurities generated are annotated in the HPLC chromatogram.

From the HPLC chromatograms of the crude product obtained when 0.9 times, 1.1 times and 8 times of NH ₄ NCS are added relative to the theoretical amount of dcbpy shown in Figure 19, it can be seen that in order to improve the purity, it is preferable to add NH ₄ NCS in excess .

Figure 19 shows the results of the HPLC analysis of the synthetic sample obtained in the experiment of changing the amount of NH ₄ NCS _. decrease at the same time. Excessive NH ₄ NCS effectively inhibited the formation of the three-coordinate complex (impurity 1).

In the complex N3-13, the addition amount of NH ₄ NCS was insufficient with respect to the stoichiometric ratio, and a large amount of tricoordinate complex (impurity 1) was generated. On the other hand, when the amount of NH ₄ NCS added is slightly excessive relative to the stoichiometric ratio, the purity is greatly improved. When NH ₄ NCS was added in an excess of 8 times the theoretical value relative to the stoichiometric ratio (theoretical amount), almost no three-coordinate complex (impurity 1) was generated, and the purity of the crude product reached 82.9%. The yield reached 47.9%.

Fig. 20 is a diagram illustrating the absorption spectrum (ethanol solution with a concentration of 1.2×10 ^-5 mol/L) of the final products of N3-4 and N3-15 synthesized by a one-pot method according to an embodiment of the present invention. Fig. 20 ( A) is the absorption spectrum of N3-4, and FIG. 20(B) is the absorption spectrum of N3-15. In FIG. 20 , the horizontal axis represents wavelength (nm), and the vertical axis represents absorption intensity (arbitrary scale). N3-4 and N3-15 showed three absorption peaks at about 295nm, 370nm and 515nm.

The above are the experimental results for finding the optimal reaction conditions in the second step. According to the results and the optimal reaction conditions in the first step mentioned above, the optimal reaction conditions in the one-pot method can be set.

(Synthesis of Ru(dcbpy) ₂ (NCS) ₂ by optimized one-pot method)

The reaction conditions described below are the reaction conditions for the synthesis of N3-15.

(first step (synthesis of Ru(dcbpy) ₂ Cl ₂ ))

Dissolve RuCl ₃ 3H ₂ O in 100 mL of DMF (solvent), put it into a three-necked flask with a thermometer, wrap the three-necked flask with aluminum foil, and stir the solution for 15 minutes in the dark and Ar gas atmosphere, and then pour into the solution Add dcbpy to it, and heat at 116°C for 8 hours in an Ar gas atmosphere protected from light.

(Second step (synthesis of Ru(dcbpy) ₂ (NCS) ₂ ))

After the reaction in the first step, the solution in the three-necked flask was cooled to room temperature, the solvent DMF was added to the three-necked flask, and 8 times the amount of NH ₄ NCS was added thereto. Under the protection of light and Ar gas, reflux and stir at 152° C. (corresponding to the boiling point of the solvent DMF) for 4 hours.

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

After the second reaction, the solution in the three-necked flask was cooled to room temperature, and the solvent was removed using a rotary evaporator, and the solution (10mL 0.5MNaOH+20mL H ₂ O) was added to the residue in the three-necked flask, and the solution was ultrasonically treated. solution for 10 minutes.

Next, this solution was filtered with a filter funnel, 1M HNO ₃ was added to the filtered solution to acidify it to pH=1.7, and a solid was precipitated.

Then, put it into a freezer (-17.5° C.) overnight to fully precipitate the solid phase. The solid phase was recovered with a Buchner funnel (suction filter funnel) and dried in a vacuum desiccator to obtain the crude product. The synthetic sample was purified by preparative HPLC to obtain the final product.

The crude product had a purity of 83% and an actual yield of 48%. In addition, the heating reaction time was 12 hours.

(comparative example)

Ru(dcbpy) ₂ (NCS) ₂ was synthesized by the same method as a known method, not by the above-mentioned one-pot method.

Fig. 21 illustrates the first and second step reactions in the known method of the comparative example of the present invention, Fig. 21(A) is the first step reaction, and Fig. 21(B) is the second step reaction.

Fig. 22 is the used raw material list of the first and second step reactions in the known method of comparative example of the present invention, and Fig. 22 (A) is the charging capacity of the first step, and Fig. 22 (B) is the second step Feeding amount. In addition, the numerical values with RuL ₂ Cl ₂ in FIG. 22(A) and the numerical values with RuL ₂ (NCS) ₂ in FIG. 22(B) represent theoretical yields.

In the first step reaction, the addition amount of dcbpy is the theoretical feed amount relative to the stoichiometric ratio of RuCl ₃ ·3H ₂ O. In the second step reaction, 2.2 times the theoretical value of NH ₄ NCS relative to the stoichiometric ratio of RuL ₂ Cl ₂ was used.

(first step (synthesis of Ru(dcbpy) ₂ Cl ₂ ))

Dissolve RuCl ₃ ·3H ₂ O in 100 mL of DMF (solvent) and put it into a three-necked flask. After passing nitrogen into the three-necked flask for 30 minutes, add dcbpy into the three-necked flask. Wrap the three-necked flask with aluminum foil, in the dark and under the protection of nitrogen, magnetically stir, and reflux at 180°C for 8 hours.

(Separation and purification of Ru(dcbpy) ₂ Cl ₂ )

After the first step reaction, the three-necked flask was cooled to room temperature. The solution was filtered using a Buchner funnel (suction funnel). The three-necked flask was placed in an ultrasonic cleaning tank, and the solid on the inner wall of the three-necked flask was eluted with DMF and filtered.

The solid was washed with DMF and MeOH, respectively, until the filtrate was colorless.

The solvent in the filtrate was removed using a rotary evaporator. To the residue was added 40 mL of 2N aqueous HCl, and stirred for 4 hours. The solution was filtered with a Buchner funnel and the solid particles were washed with water. The solid collected on the Buchner funnel was dried under vacuum to give 0.61 g, a crude yield of 48.4% (=0.61/1.26).

(Second step (synthesis of Ru(dcbpy) ₂ (NCS) ₂ ))

Dissolve NH ₄ NCS in 10 mL of water, put it into a 100 mL three-necked flask, add 20 mL of DMF, and stir for 15 minutes under the protection of nitrogen. Dissolve Ru(dcbpy) ₂ Cl ₂ in 20 mL of DMF and add it into a three-necked flask, which is wrapped with aluminum foil and protected from light. Protected with nitrogen, reflux at 119°C and stir for 5 hours.

(Separation and purification of Ru(dcbpy) ₂ (NCS) ₂ )

After the second step reaction, the solvent was removed at 65°C using a rotary evaporator. 10 mL of 1N NaOH solution and 4 mL of water were added to the flask, and stirred with a magnetic stirrer. After the residue was completely dissolved, 1N _HNO3 was added to adjust the acidity to pH=1.7.

After the dark red suspension was stirred for 10 minutes, it was placed in a refrigerator (-17.5° C.) for 3 hours to precipitate dark red fine particles. The solution was poured into centrifuge tubes in batches, and centrifuged at 5030 rpm for 5 minutes with a centrifuge.

After sucking and removing the supernatant in the centrifuge tube with a dropper (pipette), wash the solid phase with 20 ml of an acidic aqueous solution of pH=1.7 and a mixed solution of diethyl ether and petroleum ether (mixing ratio=1:1) until the centrifuge tube The supernatant layer became transparent. Place the centrifuge tubes in a vacuum desiccator and dry overnight.

As a result, 0.52 g of solid Ru(dcbpy) ₂ (NCS) ₂ was obtained, and the crude yield was 80% (=0.52/0.65). In addition, the heating reaction time was 13 hours.

FIG. 23 is a diagram illustrating an HPLC chromatogram of a synthetic sample according to a known method in a comparative example of the present invention. In FIG. 23, the horizontal axis represents dissolution time (min), and the vertical axis represents intensity (arbitrary scale).

As explained above, in the known synthetic method, it is necessary to separate and purify the intermediate product Ru(dcbpy) ₂ Cl ₂ , but in the present invention, these steps are omitted, saving the time spent on these treatments, using a The pot method can synthesize Ru(dcbpy) ₂ (NCS) ₂ in a shorter time than known synthesis methods.

In addition, by optimizing the reaction conditions of the first step and the second step in the one-pot method, the purity of the crude product can be increased to 83%, and the actual yield can be increased to 48%.

The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above-mentioned embodiments, and various modifications based on the technical idea of the present invention are possible.

(Industrial Utilization Possibility)

The ruthenium complex produced by the present invention can be suitably applied to dye-sensitized photoelectric conversion devices such as dye-sensitized solar cells.

Symbol Description

11. Sunlight 12. Transparent substrate on the photoelectrode side

13. Transparent conductive film on the photoelectrode side 14. TiO ₂ semiconductor porous film

15. Sealing material 16. Electrolyte solution

17. Conductive film on the opposite electrode side 18. Substrate on the opposite electrode side

Claims (6)

1. A method for producing a ruthenium complex, comprising:

firstly, heating ruthenium (III) trichloride and 2,2 '-bipyridyl-4, 4' -dicarboxylic acid in a reaction vessel containing a polar organic solvent to react to generate cis-dichloro-bis (2,2 '-bipyridyl-4, 4' -dicarboxylic acid) ruthenium (II) complex; and

a second step of adding an isothiocyanate to a solution in the reaction vessel containing the cis-dichloro-bis (2,2 '-bipyridine-4, 4' -dicarboxylic acid) ruthenium (II) complex produced after the first step reaction, and reacting the cis-dichloro-bis (2,2 '-bipyridine-4, 4' -dicarboxylic acid) ruthenium (II) complex with the isothiocyanate by heating to produce a cis-bis (isothiocyanato) -bis (2,2 '-bipyridine-4, 4' -dicarboxylic acid) ruthenium (II) complex; wherein,

performing the heating reaction of the first step at 105 to 120 ℃, performing the heating reaction of the second step at 105 to 160 ℃, and cooling the temperature of the solution in the reaction vessel to room temperature after the reaction of the first step;

and a third step of obtaining a cis-bis (isothiocyanato) -bis (2,2 '-bipyridine-4, 4' -dicarboxylic acid) ruthenium (II) complex from the solution in the reaction vessel by purification treatment after the second-step reaction.

2. The method for producing a ruthenium complex according to claim 1, wherein,

the second-step heating reaction is carried out in a mixed solution in which the polar organic solvent and water are mixed so that the boiling point temperature of the mixed solution is 105 ℃ to 160 ℃.

3. The method for producing a ruthenium complex according to claim 1, wherein,

dimethylformamide is used as the polar organic solvent.

4. The method for producing a ruthenium complex according to claim 1, wherein,

the purification treatment is performed by chromatography.

5. The method for producing a ruthenium complex according to claim 1, wherein,

the isothiocyanate is added in a stoichiometric ratio to the 2,2 '-bipyridine-4, 4' -dicarboxylic acid of 8 times or more.

6. The method for producing a ruthenium complex according to claim 1, wherein,

the isothiocyanate is any one of ammonium isothiocyanate, sodium isothiocyanate and potassium isothiocyanate.