JP2005343828A - Chlorophyll derivative, its metal complex, and method for oxidizing organic compound by using the same as catalyst - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chlorophyll derivative and its metal complex useful as a functional material or catalyst, and also a method for oxidizing an organic compound by using the compounds as the catalyst. <P>SOLUTION: This chlorophyll derivative or its metal complex is expressed by general formula (1), and as the metal complex, the complex coordinated with Mn(II) or Mn(III) is especially preferable. The chlorophyll derivative or its metal complex may be introduced in a lipid double molecular membrane such as a liposome membrane, etc., or fixed on an electrode substrate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chlorophyll derivative useful as an oxidation catalyst or the like and a metal complex thereof, and the present invention also relates to a method for oxidizing an organic compound using these compounds as a catalyst.

Many porphyrin derivatives have been known so far, and application in various fields has been studied and proposed (for example, see Patent Documents 1 to 3 below).
JP 2003-26690 A JP 2002-343572 A JP 2002-214233 A

  Porphyrin derivatives are known to play an important role in the metabolic processes in animals and plants. For example, hemoglobin, cytochrome enzymes, chlorophyll, etc. are all involved in the redox process. From this fact, many porphyrin derivatives and oxidation methods using them as catalysts have been developed as applications in the functional material field and the catalyst field. However, there are currently few proposals for catalysts that can efficiently carry out oxidation reactions in water systems, oil systems, and mixed systems thereof, and conventional porphyrin derivatives are limited in their application range. The function was not satisfactory.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a chlorophyll derivative useful as a functional material or a catalyst, and a metal complex thereof.

Under such circumstances, the present inventors have intensively studied, and as a result, found that the chlorophyll derivative represented by the following general formula (1) and its metal complex have excellent oxidation catalytic action, and completed the present invention. .
The present invention provides the following general formula (1):

The chlorophyll derivative represented by these or its metal complex is provided.
Moreover, this invention provides the oxidation method of the organic compound characterized by using the chlorophyll derivative represented by the said General formula (1), or its metal complex as a catalyst.

  The chlorophyll derivative of the present invention is represented by the general formula (1), and in particular, the following general formulas (2) to (4):

The thing represented by these is preferable.

  The chlorophyll derivative or metal complex thereof of the present invention is excellent in oxidation catalytic action and is particularly useful as an oxidation catalyst. Further, by using the oxidation method of the present invention using the chlorophyll derivative of the present invention or a metal complex thereof as a catalyst, an oxidation reaction in an aqueous system, an oil system, or a mixed system thereof can be efficiently performed.

The chlorophyll derivative of the present invention may be a metal complex in which a metal is coordinated to a chlorophyll skeleton. Here, the metal coordinated to the chlorophyll skeleton is not particularly limited. For example, Ag (I), Ag (II), Al (III), Ba (II), Ca (II), Co (II), Cr (III), Cu (I), Cu (II), Fe (II), Fe (III), Mg (II), Mn (II), Mn (III), Mo (II), Mo (III), Ni (II), Pb (II), Pt (II), W (II), W (III), Zn (II), etc. are mentioned. In particular, a metal complex in which Mn (II) and Mn (III) are coordinated is preferable.
The chlorophyll derivative or metal complex thereof of the present invention can be obtained by chemically modifying chlorophyll a (Chla) represented by the following general formula (5). Chlorophyll a (Chla) can be easily extracted from commercially available spinach and the like.

  PyroPheophytina of the following compound (6) can be obtained by dissolving the metal Mg removed from Chla in 2,4,6-collidine and refluxing in a nitrogen atmosphere at 120 ° C.

The PyroPheophytin a can be hydrolyzed to obtain the compound (2).
Moreover, the said compound (3) can be manufactured by condensing a compound (2) or its metal complex, and the following polymer according to the following reaction formula, for example.

This reaction can be performed according to the conditions of a normal amide formation reaction. For example, after reacting a carboxylic acid with thionyl chloride or the like to form an acid halide, this may be reacted with an aminopolyoxyalkylene whose terminal hydroxyl group may be substituted with an alkyl group. The reaction can also be carried out in the presence of a condensing agent such as N, N′-dicyclohexylcarbodiimide.
Similarly, the compound (4) can be produced, for example, by condensing the compound (2) or a metal complex thereof and L-histidine methyl ester according to the following reaction formula.

The chlorophyll derivative of the present invention or the metal complex thereof thus obtained is excellent in oxidation catalytic action and is particularly useful as an oxidation catalyst.
In order to oxidize an organic compound using the chlorophyll derivative of the present invention or a metal complex thereof, it may be used as a catalyst during a normal oxidation reaction. Here, the organic compound to be oxidized is not particularly limited, and can be applied to, for example, an oxidative decomposition reaction of CI Acid Orange 7, which is an azo dye.
In the oxidation reaction, it is preferable to use an imidazole derivative together with the chlorophyll derivative of the present invention or a metal complex thereof because this acts as an axial ligand. The imidazole derivative is preferably used 1 to 10,000 times as much as the chlorophyll derivative. Further, by using a compound having an imidazole group like the compound (4), high activity can be obtained without using imidazole in combination.

The oxidation method using the chlorophyll derivative or its metal complex of the present invention can be applied to any of aqueous systems, oil systems, and systems in which these are mixed, and can also be used in biological systems. When the reaction is carried out in an aqueous system, the pH of the reaction system is preferably 6-12, particularly around pH 8. Further, it is preferable to use hydrogen peroxide or the like as the oxidizing agent.
When the chlorophyll derivative or the metal complex thereof of the present invention is used in an aqueous system, the compound (3) can be used as it is, but the compounds (2) and (4) are used in a surfactant micelle or a lipid membrane such as a liposome membrane. It can be used by being introduced into a molecular film.
As surfactants that form micelles, octyl glucoside (nonionic), sodium dodecyl sulfate (anionic), cetyltrimethylammonium bromide (cationic), etc. can be used, and they are not particularly limited and are suitable for oxidizing substances You can choose.

  Egg lipid phosphatidylcholine (EggPC), dicetyl phosphate (DCP), dihexadecyldimethylammonium bromide (DHDAB), etc. can be used as the lipid used to prepare the liposome. It is only necessary to prepare a material suitable for an oxidizing substance such as a liposome membrane having a cationic property, EggPC and DCP, and an anionic liposome membrane on the membrane surface. Moreover, the stability of the catalyst can be improved by introducing the chlorophyll derivative or metal complex of the present invention into the liposome membrane.

In addition, by organizing the chlorophyll derivative or metal complex of the present invention on an electrode, it can be used as a heterogeneous catalyst. When used, in addition to using an oxidizing agent such as hydrogen peroxide, the substrate can also be oxidized using electron transfer between the electrode and the chlorophyll derivative. At that time, it is more preferable to supply oxygen.
As a means for organizing on the electrode, physical adsorption, electrostatic interaction, covalent bond, or the like can be used. For example, the ITO electrode was immersed in a piranha solution (concentrated sulfuric acid: hydrogen peroxide = 7: 3) for 2 minutes, then washed with distilled water, methanol, and chloroform, and then a predetermined amount of chlorophyll derivative and lipid were dissolved in chloroform. The thing was dripped and air-dried at room temperature. Thereafter, warm air can be applied for 2 minutes to remove chloroform remaining in the membrane, so that it can be organized on the electrode. As the lipid, commercially available products such as dipalmitoyl phosphatidylcholine (DPPC) and egg yolk phosphatidylcholine (EggPC) can be used as they are and are not particularly limited.

The present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.
(Example 1)
Stir Chl a in acetic acid for several minutes to remove central metal Mg. 100 mg of pheophytin a (Pheo a) dissolved in 10 ml of 2,4,6-collidine is refluxed at 120 ° C in a nitrogen atmosphere for 3 hours. went. Then, after standing to cool at room temperature and vacuum-drying, 200 ml of 12.5% sulfuric acid / methanol was added, and it stirred at room temperature for 2 hours in nitrogen atmosphere. After completion of the reaction, the reaction mixture was neutralized with 5N sodium hydroxide while cooling with ice, then extracted with methylene chloride into the organic phase, and the solvent was distilled off. The obtained powder was dissolved in 400 ml of 5N hydrochloric acid, and stirred at room temperature in a nitrogen atmosphere for 3.5 hours. After completion of the reaction, the reaction mixture was neutralized with 5N sodium hydroxide while cooling with ice, then extracted with methylene chloride into the organic phase, and the solvent was distilled off. Next, PyroPheophorbide a (PPheide a) was obtained in a yield of 57.3% by separation and purification by silica gel chromatography. MALDI-TOF-MASS (m / z 534.04 MH +), ¹ H-NMR (CDCl ₃ ) 9.47, 9.35, and 8.53 (s, 1H, 5-H, 10-H, and 20-H, respectively); 8.00 (dd , J) 17.7, 11.4 Hz, 1H, 31-CH = CH ₂ ); 6.27 (d, 1H, trans-3 ² -CH = CH ₂ ); 6.15 (d, 1H, cis-3 ² -CH = CH ₂₎ ); 5.18 (ABX, 2H, 13 ² -CH ₂ ); 4.47 (q, 1H for 18-H); 4.29 (m, 1H for 17-H); 3.68 (q, 2H, 8-CH ₂ -CH ₃ ); 3.64, 3.39, and 3.22 (s, 3H, 12-CH ₃ , 2-CH ₃ and 7-CH ₃ respectively); 2.65 and 2.32 (m, 2H, for 2 × 17 ¹ -H and 2 × 17, respectively) ² -H); 1.81 (d, 3H, 18-CH ₃ ); 1.70 (t, 3H, 8-CH ₂ CH ₃ ), 0.87 and -1.35 (brs, 1H, 2 × NH, respectively).

(Example 2)
15 mg of PPheide a and 2 equivalents each of N-hydroxysuccinimide and N, N′-dicyclohexylcarbodiimide were dissolved in 2 ml of chloroform and reacted at room temperature for 1 hour. Next, 125 mg of PEG ₅₀₀₀ was dissolved in 1 ml of chlorophyll, a few drops of triethylamine was added, and the reaction was carried out at room temperature for 24 hours. Next, it was purified by ultrafiltration, and PEG-PPheide a was obtained in a yield of 76.9% by freeze drying. ¹ H-NMR (CDCl ₃ ) 9.47, 9.35, and 8.53 (s, 1H, 5-H, 10-H, and 20-H, respectively); 8.00 (dd, J) 17.7, 11.4 Hz, 1H, 31-CH = CH ₂ ); 6.27 (d, 1H, trans-3 ² -CH = CH ₂ ); 6.15 (d, 1H, cis-3 ² -CH = CH ₂ ); 5.97 (amide 1H, NH); 5.18 (ABX , 2H, 13 ² -CH ₂ ); 4.47 (q, 1H for 18-H); 4.29 (m, 1H for 17-H); 3.68 (q, 2H, 8-CH ₂ -CH ₃ ); 3.64, ( PEG, 456H,-[OCH ₂ , -CH ₂ ]-); 2.65 and 2.32 (m, 2H, for 2 _ 17 ¹ -H and 2 × 17 ² -H, respectively); 1.81 (d, 3H, 18-CH ₃ ); 1.70 (t, 3H, 8-CH ₂ CH ₃ ), 0.87 and -1.35 (brs, 1H, 2 × NH respectively).

(Example 3)
PPheide a 29.1 mg, N-hydroxysuccinimide 25.1 mg, and N, N′-dicyclohexylcarbodiimide 45.0 mg were dissolved in 5 ml of chloroform and stirred at room temperature for 2 hours. Separately, 26.3 mg of L-histidine methyl ester dihydrochloride dissolved in 2 ml of chloroform to which several drops of triethylamine were added was gradually added. After stirring for 20 hours, the solvent was distilled off, and the residue was extracted with methylene chloride. After distilling off methylene chloride, purification was performed with a silica gel column to obtain PPheide a- (L-HisOMe) powder in a yield of 19.8%. MALDI-TOF-MASS (m / z 687.17 MH +), 1H NMR (CDCl 3) 9.38 (1H, s, C5 -H), 9.34 (1H, s, C10 -H), 8.53 (1H, s, C20 -H ), 8.03 (1H, q, C3 ¹ -CH =), 7.36 (1H, s, Imidazole-NCHNH), 6.60 (1H, s, His-NH), 6.30 (1H, d, C3 ² = CH ₂ trans) , 6.15 (1H, d, C3 ² = CH ₂ cis), 5.12 (2H, q, C13 ² -CH _2- ), 4.71 (1H, s, His-CH), 4.50 (1H, m, C18 -H) , 4.32 (1H, m, C17 -H), 3.61 (2H, q, C8 1 -CH 2 -), 3.61 (3H, s, C12 -CH 3), 3.49 (3H, s, C2 -CH 3), 3.22 (3H, s, C7 -CH ₃ ), 2.93 (2H, d, His-CH2), 2.65 (2H, m, C17 ¹ -CH ₂ -trans), 2.64 (2H, m, C17 ² -CH _2- trans), 2.45 (2H, m, C17 ² -CH ₂ ), 1.82 (3H, d, C18 -CH ₃ ), 1.66 (3H, t, C8 ² -CH ₃ ), 0.87 (1H, br s, -NH ), -1.65 (1H, br s, -NH).

Example 4
2 mg of acetic acid was added to 10 mg of PPheide a and dissolved, and 23 mg of 5-fold equivalent manganese (II) acetate tetrahydrate was dissolved in 2 ml of acetic acid and refluxed at 60 ° C. for 1 hour in a nitrogen atmosphere. After completion of the reaction, hexane was added in excess and the mixture was filtered. The resulting precipitate was washed with a diethyl ether-water separatory funnel, and the water phase was extracted into the organic phase with methylene chloride. As a result, Mn-PyroChlorophyllide a (MnPChlide a) was obtained in a yield of 86.1%.

(Example 5)
Acetic acid (2 ml) was added to 10 mg of PEG-PPheide a and dissolved, and 5 mg equivalent of manganese (II) acetate tetrahydrate (23 mg) was dissolved in acetic acid (2 ml) and refluxed at 60 ° C. for 1 hour in a nitrogen atmosphere. . After completion of the reaction, hexane was added in excess and the mixture was filtered. The resulting precipitate was washed with a diethyl ether-water separatory funnel, and the water phase was extracted into the organic phase with methylene chloride. As a result, PEG-MnPChlide a was obtained with a yield of 89.3%.

(Example 6)
2 mg of acetic acid is dissolved in 10 mg of PPheide a- (L-HisOMe), and 23 mg of 5 times equivalent manganese (II) acetate tetrahydrate is dissolved in 2 ml of acetic acid at 60 ° C. in a nitrogen atmosphere. Refluxed for 1 hour. After completion of the reaction, hexane was added in excess and the mixture was filtered. The resulting precipitate was washed with a diethyl ether-water separatory funnel, and the water phase was extracted into the organic phase with methylene chloride. As a result, MnPChlide a- (L-HisOMe) was obtained in a yield of 89.1%.

(Example 7)
EggPC 100 mg (1.43 × 10 ⁻⁴ mol) and MnPChlide a 2.4 × 10 ⁻⁶ mol dissolved in chloroform were placed in a round bottom flask and slowly distilled off with a rotary evaporator to prepare a thin film. Thereafter, the chloroform was completely removed by vacuum drying, and the thin film was peeled off with 2.5 ml of 10 mM Tris-HCl buffer (pH 8), and the freeze-thawing method was performed until the thin film was completely removed to adjust the MLV. Subsequently, SUV was adjusted by sonication for 10 minutes in an ice bath, gel filtration was performed using Sephadex G50 fine, and purification was performed. Similarly, charged liposomes were prepared. [Cationic liposome EggPC: DHDAB = 4: 1 (mol / mol), anionic liposome EggPC: DCP = 4: 1 (mol / mol)]

(Example 8)
Oxidation catalytic ability for CI Acid Orange 7 in hydrogen peroxide (aqueous): Tris-HCl buffer (pH) containing azo dye CI Acid Orange 7 (λ _max 484 nm) 100 mM and imidazole 0.1 M for 10 mM of various chlorophyll derivatives 8) A solution was prepared, and 30 mM of 31% hydrogen peroxide was added thereto, and the change in absorbance of CI Acid Orange 7 was observed to evaluate the degradation of CI Acid Orange 7. In the fading reaction of the dye, it is known that the pseudo first order reaction equation is obeyed at the initial stage of the reaction, and the pseudo first order rate constant (k _obs ) was obtained from the following equation.
ln (C ₀ / C _t ) = k _obs t
However, C ₀ : Substrate initial concentration, C _t : Substrate concentration after t minutes Table 1 shows the results of comparing the compound of the present invention with the porphyrin derivatives and enzymes of the following comparative examples. As a result, the compound of the present invention showed very high activity, and higher catalytic activity than that of the enzyme was also observed.

(Comparative Example 1)
Compound with the following structure

(Comparative Example 2)
Compound with the following structure

(Comparative Example 3)
The following compounds in which the central metal Mg of chlorophyll a is replaced with Mn

(Comparative Example 4)
Horseradish peroxidase, a natural enzyme (for EIA) (Wako Pure Chemical Industries)
Enzyme activity 200U / mg, Rz = 3.11

  Table 1 below shows the oxidative degradation rate constant of C.I. Acid Orange 7 using each porphyrin derivative with and without imidazole as a catalyst.

(Example 7)
Preparation of lipid membrane-coated electrode: A solution of MnPChlide a / DMPC = 150 mmol / g dissolved in chloroform was dropped onto a leveled ITO electrode so as to be 150 nmol / mg per 1 cm ² of the electrode, and air-dried at room temperature. Thereafter, the chloroform present in the membrane was completely removed with warm air. In this experimental system, the ITO electrode was treated to 2 cm ² .

(Example 8)
Decomposition of azo dye using electron transfer between electrode and chlorophyll: Measurement was performed in Tris-HCl buffer (pH 8.0). As shown in FIG. 1, a three-electrode cell is used, an Ag / AgCl / 0.1 M KCl electrode is used as a reference electrode, a platinum electrode is used as a counter electrode, and an ITO electrode in which a chlorophyll derivative and a lipid membrane are organized as a working electrode . A constant potential was applied to the working electrode, and the change in absorbance at 484 nm, which is the maximum absorption wavelength of CI Acid Orange 7, was measured for 30 minutes to confirm oxidative degradation of the azo dye (FIG. 2).

FIG. 1 is a view showing the structure of a three-electrode cell produced in Example 8. FIG. 2 is a diagram showing the state of decomposition of C.I. Acid Orange 7 by MnPClide a organized in an ITO electrode.

Claims (7)

The following general formula (1):

And a metal complex thereof. The metal complex has Ag (I), Ag (II), Al (III), Ba (II), Ca (II), Co (II), Cr (III) on the chlorophyll skeleton in the general formula (1). ), Cu (I), Cu (II), Fe (II), Fe (III), Mg (II), Mn (II), Mn (III), Mo (II), Mo (III), Ni (II ), Pb (II), Pt (II), W (II), W (III) and a metal selected from the group consisting of Zn (II) are coordinated compounds. Metal complexes of chlorophyll derivatives of The chlorophyll derivative and metal complex thereof according to claim 1 or 2, which are introduced into a lipid bilayer such as a liposome membrane. The chlorophyll derivative and the metal complex thereof according to any one of claims 1 to 3, which are immobilized on an electrode substrate. A method for oxidizing an organic compound, wherein the chlorophyll derivative or a metal complex thereof according to any one of claims 1 to 4 is used as a catalyst. 6. The oxidation method according to claim 5, wherein the oxidation is performed in the presence of an imidazole derivative. An organic compound oxidation method using electron transfer between an electrode and the chlorophyll derivative or metal complex according to claim 4.