JPH01238584A - Porphyrin derivative and photoinduced hydrogen evolution - Google Patents

Abstract

NEW MATERIAL:A compound shown by formula I (three of R1-R4 are 1-3 groups shown by the formula II and the rest is group shown by formula III: n is 2-6; X is H or alkali metal; M is polyvalent metal). USE:A light hydrogen generating agent. PREPARATION:5-(4-Pyridyl)10,15,20-tri(ethylcarboxyphenyl)porphyrin is synthesized from 4-carboxybenzaldehyde ethyl ester, (4-pyridyl)aldehyde and (2- aldehyde)pyrrole. 5-(4-Pyridyl)10,15,20-tri(ethylcarboxyphenyl)porphyrin is reacted with an extremely excess amount of an alpha,omega-dibromoalkane in toluene to give a compound wherein a terminal brominated methylene group is introduced into pyridyl group of porphyrin. This compound is reacted with an excess amount of N-methyl-4,4'-bipyridinium salt iodide in DMF to give a viologen- containing porphyrin compound. This compound is purified, hydrolyzed with an excess amount of an alkali metal hydroxide in ethanol, then incorporated with ten times as much as a metallic salt of acetic acid and refluxed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel porphyrin derivative and its application, and specifically relates to a viologen-bound porphyrin and its use in a photohydrogen generation method.

[Conventional technology]

The hydrogen generation reaction from water using light energy is a reaction that is attracting attention because it converts solar energy into chemical energy. Several methods have been proposed regarding this photohydrogen generation reaction.

In this photohydrogen generation reaction, the following four components consisting of an electron donor (CD), a photosensitizer (S), an electron carrier (C), and a catalyst are often used.

The present inventors have reported that water-soluble zinc-porphyrin is effective as a photosensitizer, methyl viologen is effective as an electron carrier, and the enzyme hydrogenase is effective as a catalyst in this electron transport system. (Bu, 1.!, Chem.

5oc-Jpn, ) Vol. 59, pp. 3967-3968 (I986) i, Vol. 60, pp. 1243-1247 (
I987); Photochemistry and Photobiology (Photochem, PhotobioJ,
) Vol. 40, pp. 1-5 (I986)).

Furthermore, in the above reaction, a photoexcited photosensitizer (
The charge separation process caused by the reaction between S★) and an electron carrier is one of the important steps that determines the rate of hydrogen generation. Therefore, for the purpose of more efficient photohydrogen generation, we investigated porphyrins to which viologen is bonded, and synthesized and reported a porphyrin compound to which four viologen groups are bonded.
J.

Wall, CataJ, ) Volume 36, Nos. 201-20
3 pages (I986)).

[Problem to be solved by the invention]

In photohydrogen generation reactions that convert solar energy into chemical energy, porphyrin compounds with four viologen groups bonded have poor water solubility and can only be used in dilute solutions, resulting in poor conversion efficiency.

The present invention provides a novel porphyrin derivative that is water-soluble and has a viologen group, and further provides a photohydrogen generation method using this new porphyrin derivative.

[Means to solve the problem]

The present invention is a porphyrin derivative represented by general formula (I).

(In the formula, 1 to 3 of R11R2s R3 and R4
Each represents a hydrogen atom or an alkali metal, and M represents a polyvalent metal. ) The present invention also provides a photohydrogen generation reaction consisting of an electron donor, a photosensitizer, an electron carrier, and a catalyst, in which the photosensitizer and the electron carrier are porphyrin derivatives represented by the above general formula (I). This is a photo-hydrogen generation method.

In the general formula (I) of the present invention, n is an integer of 2 to 6, and this methylene chain is necessary to maintain an appropriate distance between the porphyrin ring and viologen and control charge transfer. When n is 1, the distance between porphyrin II and viologen is short, so the reverse electron transfer reaction is fast, and when n exceeds 6, the electron transfer from the porphyrin ring to viologen becomes slow, which is not preferable.

X in general formula (I) represents a hydrogen atom or an alkali metal, and preferred examples of the alkali metal include sodium, potassium, and lithium.

Further, M is a polyvalent metal, preferably zinc, magnesium, cobalt, bromine, copper, nickel, or the like.

The porphyrin derivative of general formula (I) of the present invention can be obtained by the following reaction method.

4-carboxybenzaldehyde ethyl ester;
From (4-pyridyl)aldehyde and (2-aldehyde)pyrrole, 5-(4-pyridyl)10.15.20-)
Synthesize (ethylcarboxyphenyl)porphyrin. This is reacted with a large excess of α,ω-dibu-pmoalkane in toluene to obtain a compound in which a methylene chain with a brominated terminal is introduced into the pyridyl group of porphyrin. This was dissolved in dimethyl formaldehyde with excess N-methyl-
A porphyrin compound having a viologen group is obtained by reacting with 4,4'-bipyridinium salt iodide. After this is purified, it is hydrolyzed in ethanol with an excess of alkali metal aqueous dispersion, and then about 10 times the amount of metal acetate is added and refluxed to obtain the porphyrin derivative of general formula (T).

The porphyrin derivative of the present invention is a compound in which a water-soluble anionic porphyrin, which is highly active as a photosensitizer, and viologen, which has an electron transfer function as an electron acceptor, are bonded by a methylene chain and placed in close proximity. Therefore, due to the intramolecular electron transfer reaction between the photosensitizing part and the electron accepting part, one molecule has two functions: a photosensitizing action and an electron transporting action. Therefore, in a photohydrogen generation reaction consisting of an electron donor, a photosensitizer, an electron carrier, and a catalyst, the porphyrin derivative of the present invention is used as a photosensitizer and an electron carrier.

In the photohydrogen generation reaction using the porphyrin derivative of the present invention as a photosensitizer and an electron carrier, it is preferable to use reduced nicotinamide adenine dinucleotide as the electron donor and hydrogenase as the catalyst.

The photohydrogen generation reaction can be performed by freezing and degassing the solution to remove oxygen, and then irradiating the solution with light.

〔Effect of the invention〕

Since the porphyrin derivative of the present invention has a carboxyl group and has improved water solubility, it can be made into a highly concentrated solution compared to conventional nonionic derivatives.

Furthermore, since it has a porphyrin ring and a viologen in the same molecule, it can act as a photosensitizer and an electron carrier at the same time in the photohydrogen generation reaction.

Therefore, by using the porphyrin derivative of the present invention, it is possible to improve the conversion efficiency of the photohydrogen generation reaction that converts solar energy into chemical energy.

〔Example〕

The present invention will be explained in detail by way of examples.

Example 1 In a four-way flask equipped with a stirrer, a condenser, a thermometer and a dropping funnel, 4-carboxybenzaldehyde ethyl ester 18.8.1', (4-pyridyl)aldehyde 4. 10.8 J' of (2-aldehyde)pyrrole was added dropwise over 1 hour under reflux at 130-135"C. After the completion of the dropwise addition, the reaction was further continued for 2 hours, and then the temperature was lowered to room temperature. The precipitated crystals were filtered and washed with methanol, followed by column chromatography (φ30mXIQQcm) using silica gel (Wako Tsumugi Pharmaceutical ■, Wakogel B-0).

A mixture of chloroform and ethyl ether (8:2) was obtained. This intermediate 0.37' was placed in 50P of toluene, α
, adding ω-dibromobutane 157' to 120-13
The reaction was carried out at 0''C for 5 hours to quaternize the pyridyl group, yielding a porphyrin compound with 4 methylene chains (0.1/).

This was dissolved in dimethylformamide IQQjIl at 0.0%.
It was reacted with 3 N-methyl-4,4'-bipyridinium salt iodides at 160''C under reflux for 2 days.
After extraction with form, wash with water to remove unreacted N-methyl-4.
, 4'-bipyridinium salt was removed. bio beads 5
X-1 (Biola.

The product was isolated and purified by gel filtration using a porphyrin compound (0.057'), in which M is a hydrogen atom, and has a viologen group.

NM of this porphyrin compound having a viologen group
The R spectrum is as shown in FIG.

This porphyrin compound having a viologen group was hydrolyzed in methanol with a large excess of sodium hydroxide under reflux for 6 hours, and then kO,05JR of zinc acetate was added to the same solution and reacted for 5 hours to form a porphyrin ring. Introduced zinc. A porphyrin derivative having lead in the general formula (I) was obtained.

Example 2 The same procedure as in Example 1 was carried out except that α, ω-dibromohexane was used instead of α, ω-, Zigp Mozdan, so that in general formula (I), R1=R2= R3=CH3,M A zinc porphyrin derivative was obtained.

Example 3 Using α,ω-dibromopentane, a porphyrin derivative of Example 2 and CH3 was obtained.

Example 4 The porphyrin derivatives obtained in Examples 1 to 3 were placed in a reactor (inner capacity 15 m) using a Virex cell (2 x 10
-6 mol, reduced nicotinamide adenine dinucleotide I
0, 2 units (origin) and Tris buffer IQi+/ were added and the pH was adjusted to 7. In order to remove dissolved oxygen, freezing and deaeration were repeated three times, and then light irradiation was performed while stirring at 30"C. A 200W tungsten lamp (Kondo Sylvania 4 KP-8) was used as the light source, and a distance of 3901 m or less was used. Light with a wavelength of was removed using an optical filter (Shi Toshiba, L-39).

The generated hydrogen was collected using a gas chromatograph (Hitachi Hitachi 164. Filler, activated carbon, 0.5 x 30 Qcm,
The amount was determined using a carrier gas (nitrogen).

The results obtained are shown in Figure 2.

In FIG. 2, ZnPC4V, Z'nPCsV and ZnPCsV represent the porphyrin derivatives obtained in Examples 1.2 and 3, respectively.

In addition, 1 unit of hydrogenase was determined as follows.

Add 0.5 m of hydrogenase solution to methyl viologen (
4X 10-5mo)/dgo)+Na2S2O4(5
, 7X 10-2 mojl/d) with a total amount of 5. 〇－
The reaction was carried out at 30°C in a solution of pH 7.0, the amount of hydrogen generated was measured, and the activity of hydrogenase when it had the ability to generate 1 μmo of hydrogen per minute was defined as 1 unit.

[Brief explanation of the drawing]

FIG. 1 is an NMR spectrum diagram of the porphyrin compound having a viologen group obtained in Example 1. Second
The figure is a diagram showing the results of the photohydrogen generation reaction according to Example 4.

Claims (1)

[Claims] 1. A porphyrin derivative represented by general formula (I). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (In the formula, 1 to 3 of R_1, R_2, R_3, and R_4 are ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and the rest are ▲mathematical formulas, chemical formulas. , tables, etc. are ▼, and n is 2~
represents an integer of 6, X represents a hydrogen atom or an alkali metal, and M represents a polyvalent metal. 2. A photohydrogen generation method comprising an electron donor, a photosensitizer, an electron carrier, and a catalyst, wherein the photosensitizer and the electron carrier are the porphyrin derivative according to claim 1.