JPH0570455A - Bipyridinium salt extended with 5-membered heterocyclic ring and its production - Google Patents

Abstract

PURPOSE:To obtain a new bipyridinium salt, extended with a 5-membered heterocyclic ring, capable of exhibiting electrochemical characteristics comparable to those of methylviologen, having a high absorption coefficient and useful as an electrochromic material. CONSTITUTION:A bipyridinium salt, extended with a 5-membered heterocylic rind and expressed by formula I (X is S, O, Se or N-CH3; R is 1-18C alkyl, alkylthiomethyl, alkoxymethyl, cyanomethyl, benzyl alkoxycarbonyl, formyl or cyano), e.g. 2,5-bis(N-methyl-4-pyridinium)thiophene bistetrafluoroborate. The compound expressed by formula I is obtained by introducing substituent groups into respective N atoms of bipyridines expressed by formula II.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel compound useful as an electrochromic material and the like and a method for producing the same.

[0002]

2. Description of the Related Art Viologens, which are bipyridine compounds, are recognized today as the most excellent electrochromic materials because of their reversibility in an electrochemical redox reaction and the accompanying remarkable color change. For example, the radical cation of viologen exhibits a strong absorption near 397 nm and a broad and slightly weak absorption near 600 nm. Since viologen is colorless, it is used as an electrochromic material by utilizing the absorption in the visible region (absorption near 600 nm).

Further, the above viologens are used in a system (photoelectric conversion system) for converting sunlight into electric energy because they generate radical cations that absorb in the visible part in a photoelectrochemical process. Furthermore, it has been attracting attention and studied as an electron accepting component in an artificial photosynthesis system.

[0004]

By the way, as described above, viologens exhibit excellent characteristics as electrochromic materials, but in the oxidation-reduction process, viologens have wavelengths longer than absorption near 600 nm. Has a problem that absorption does not appear, and a polymer is deposited on the electrode surface while the redox reaction is repeated, which causes deterioration of the electrode surface.

That is, in the above viologen, 2
Since two pyridine rings are directly bonded to each other, the hydrogen atoms in the ortho positions of the two pyridine rings cause steric repulsion in a planar structure, as in biphenyl. Therefore, the two pyridine rings are likely to be twisted from the plane. This is considered to be the cause of polymer precipitation.

Therefore, in order to prevent the precipitation of the above-mentioned polymer, it is an object to alleviate the steric repulsion of ortho hydrogen to provide a compound having good flatness. Further, in order to cope with various uses, it is an object to provide a compound that absorbs in a wavelength range different from that of a viologen radical and a compound that has a stronger absorption intensity in the visible region. Up to now, various attempts have been made to improve these drawbacks by changing the substituents on the N atom of viologen, but the expected effects have not been obtained.

The present invention has been proposed in view of the above conventional circumstances, and provides a novel compound that easily takes a planar structure and does not cause electrode deterioration due to precipitation of a polymer, and a method for producing the same. The purpose is to Another object of the present invention is to provide a novel compound having a strong absorption intensity in the visible region and exhibiting absorption in a wavelength range different from that of a viologen radical, and a method for producing the same.

[0008]

Means for Solving the Problems The present inventor has conducted extensive studies on an extended conjugated viologen in order to solve the above problems. As a result, bipyridinium compounds expanded with five-membered rings such as thiophene ring and furan ring tend to have a planar structure, and their radical cations show extremely strong absorption maximum in the visible region, which is not seen in viologen. We have found that the region also shows absorption.

The present invention has been completed based on these findings. That is, the compound of the first invention of the present invention has the following chemical formula 3 [wherein X is S, O, S
e or N—CH ₃ (hereinafter, the methyl group CH _{3 is referred} to as Me), R is an alkyl group having 1 to 18 carbon atoms,
It is an alkylthiomethyl group, an alkoxymethyl group, a cyanomethyl group, a benzyl group, an alkoxycarbonyl group, a formyl group or a cyano group. ] Is shown.

[0010]

[Chemical 3]

Further, the production method which is the second invention of the present invention comprises each of the bipyridines represented by the following chemical formula 4 (wherein X is S, O, Se or N-Me). N
It is characterized by introducing a substituent on an atom.

[0012]

[Chemical 4]

The compound of the present invention can be said to be a bipyridinium salt extended with a five-membered heterocyclic ring, which is a novel compound not yet published in the literature. The hetero five-membered ring includes a thiophene ring, a furan ring, a selenophene ring, and an N-methylpyrrole ring, and compounds expanded by these are 2,5-bis (N-substituted-4-pyridinium) thiophene (abbreviation), respectively. BPT), 2,5-bis (N-substituted-4-pyridinium) furan (abbreviation BPF), 2,5-bis (N-
Substituted-4-pyridinium) selenophene (abbreviation BP)
S), 2,5-bis (N-substituted-4-pyridinium) N
-Methylpyrrole (abbreviation BPMP).

All of these compounds can be synthesized by synthesizing bipyridines expanded with a five-membered ring and introducing a substituent on the N atom. For example,
The method for synthesizing 2,5-bis (N-substituted-4-pyridinium) thiophene is as follows. First, 2 molar equivalents of 4-stannylpyridine to 2,5-dibromothiophene are reacted in the presence of a palladium catalyst,
2,5-Bi- (4-pyridyl) thiophene represented by the following chemical formula 5 is obtained.

[0015]

[Chemical 5]

[0016] Next, the 2,5-bi - (4-pyridyl) thiophene and trimethyl oxy tetrafluoroborate _{^{(Me 3 O + BF 4 -}} ), or by reacting a halide such as an alkyl halide, the Bipirijiumu salt Obtainable. Specifically, 2,5-bi- (4-
By reacting pyridyl) thiophene with trimethyloxyfluoroborate, 2,5
-Bis (N-methyl-4-pyridinium) thiophene bistetrafluoroborate can be obtained.

[0017]

[Chemical 6]

Further, by reacting 2,5-bi- (4-pyridyl) thiophene with methyl bromide or heptyl bromide, 2,5-bis (N) represented by the following chemical formula 7 is obtained.
-Methyl-4-pyridinium) thiophene dibromide or 2,5-bis (N-heptyl-4-pyridinium) thiophene dibromide represented by the following chemical formula 8 is obtained.

[0019]

[Chemical 7]

[0020]

[Chemical 8]

Similarly, by reacting 2,5-bi- (4-pyridyl) thiophene with acetonitrile iodide, 2,5-bis (N-cyanomethyl-4-pyridinium) thiophene represented by the following chemical formula 9 is obtained. The diiodide is obtained.

[0022]

[Chemical 9]

2,5-bis (N-substituted-4-pyridinium) furan, 2,5-bis (N-substituted-4-pyridinium) selenophene, 2,5-bis (N-substituted-4-pyridinium) N -Methylpyrrole can also be synthesized by the same reaction route. That is, 2,5-
By reacting 2 molar equivalents of 4-stannylpyridine with respect to dibromofuran in the presence of a palladium catalyst,
2,5-bi- (4-pyridyl) represented by the following chemical formula 10
Get francs.

[0024]

[Chemical 10]

The thus obtained 2,5-bi- (4
By reacting -pyridyl) furan with trimethyloxyfluoroborate
-Bis (N-methyl-4-pyridinium) furan bistetrafluoroborate is obtained.

[0026]

[Chemical 11]

The same applies to 2,5-bis (N-substituted-4-pyridinium) selenophene and 2,5-bis (N-substituted-4-pyridinium) N-methylpyrrole.
By reacting 2,5-dibromoselenophene or 2,5-dibromo-N-methylpyrrole with 2 molar equivalents of 4-stannylpyridine in the presence of a palladium catalyst, 5-bi- (4-pyridyl) selenophene or 2,5 represented by Chemical formula 13
-Bi- (4-pyridyl) N-methylpyrrole is obtained.

[0028]

[Chemical formula 12]

[0029]

[Chemical 13]

Then, by reacting these compounds with methyl bromide, 2,5-bis (N
-Methyl-4-pyridinium) selenophene dibromide,
Alternatively, 2,5-bis (N-methyl-
4-Pyridinium) N-methylpyrrole dibromide is obtained.

[0031]

[Chemical 14]

[0032]

[Chemical 15]

[0033]

EXAMPLES Specific examples of the present invention will be described in detail below.

2,5-bi- (4-pyridyl) thiophene
Synthesis of 2,5-dibromothiophene under 1.08
g (4.46 mmol) and 4-stannylpyridine 2.3
8 g (9.82 mmol) was dissolved in 44 ml of dry toluene, and Pd (PPh ₃ ) ₄ 1.0
3 g (0.89 mmol) was added and the resulting mixture was heated to reflux for 4 hours 30 minutes.

After cooling the reaction solution to room temperature, 200 ml of chloroform was added, and the organic layer was first mixed with 1NNH.
_It was washed with an aqueous ₄ OH solution, then with a saturated saline solution, and dried with anhydrous sodium sulfate. The solvent was removed, the residue was dissolved in tetrahydrofuran (THF), purified by gel permeation chromatography (GPC), and then passed through silica gel chromatography (eluted with acetone) to give a colorless substance having a melting point of 170 to 172 ° C. As a needle crystal, 587 mg (yield 55%) of 2,5-bi- (4-pyridyl) thiophene shown in Chemical formula 5 was obtained. The obtained 2,5-bi- (4-pyridyl) thiophene was recrystallized from acetonitrile to give a pure product.

<Physical data of 2,5-bi- (4-pyridyl) thiophene> 1. Melting point 170-172 ° C (colorless needle crystals) 1. Electronic spectrum: in MeCN λ _max nm (log
ε) 216 (3.95), 233 (3.97), 330
(4.48) 3. IR (KBr): cm ^-1 3050, 3034, 1589, 1410, 1286,
1215, 987 816, 681 4. ¹ HNMR: in CDCl ₃ at 200 Hz (δ i
n ppm, J in Hz) 7.50 (4H, dd, J = 4.8, 2.0) 7.52 (2H, s) 8.64 (4H, dd, J = 4.8, 2.0) ) 5. ¹³ CNMR: in CDCl ₃ at 50 Hz (δ in
ppm) 119.7, 126.5, 140.7, 142.6, 1
50.6 6. DEI-MS 240 (M ^{+ +} 2,4%), 239 (M ⁺ +1,17.
2%) 238 (M ⁺ , 100%), 237 (M ⁺ -1, 4.2)
%)

2,5-bis (N-methyl-4-pyridini)
Um) thiophene bistetrafluoroborate synthesis Under an argon stream, 12 ml of dry acetonitrile was added to 100 mg (0.42 mmol) of 2,5-bi- (4-pyridyl) thiophene and heated to 50 to 55 ° C.
The 2,5-bi- (4-pyridyl) thiophene was completely dissolved in acetonitrile.

To this solution, 250 mg (1.68 mmol) of trimethyloxyfluoroborate (Me ₃ O ⁺ BF ₄ ⁻ ) was added all at once, and then at 95 to 100 ° C. for 3 hours 3 hours.
Stir for 0 minutes. The reaction solution is cooled to room temperature, and acetic acid 2
After adding 3 ml, 20 ml of dry ether was added, and the precipitated crystals were separated by filtration.

The crystals obtained were washed with acetic acid, benzene, and then with ether, dissolved in acetonitrile by heating, cooled to room temperature, and benzene was added to precipitate crystals. As a result, 2,5-bis (N-methyl-4-) shown in Chemical formula 6 above was obtained as pale yellow crystals having a melting point of 285 ° C. or higher.
175 mg (yield 94%) of pyridinium) thiophene bis tetrafluoroborate was obtained.

The obtained 2,5-bis (N-methyl-4-)
Pyridinium) thiophene bis tetrafluoroborate became a pure product when recrystallized from a mixed solvent of acetonitrile-methanol.

<Physical data of 2,5-bis (N-methyl-4-pyridinium) thiophenebistetrafluoroborate> Melting point 285 ° C or higher (pale yellow needle crystals) 2. Electronic spectrum: in MeCN λ _max nm (log
ε) 243 (3.95), 281 (3.84), 369
(4.61) 3. IR (KBr): cm ^-1 3074, 3030, 1639, 1542, 1296,
1057 1036 4. ¹ HNMR: in CF ₃ COOD at 200 Hz (δ in
ppm, J in Hz) 4.47 (6H, s, NMe) 8.13 (2H, s) 8.32 (4H, d, J = 6.0) 8.72 (4H, d, J = 6. 0) 5. ¹³ CNMR: in CF ₃ COOD at 50 Hz (δ in pp
m) 49.5 (NMe), 125.8, 135.0, 14
5.0 147.4, 151.1 6. X-ray crystallographic analysis See Figures 1 to 3 (numerical values in the figures are interatomic distances, bond angles,
Indicates the distance between layers. ) 7. Electronic spectrum of radical cation: in MeCN 568 nm, 911 nm, 1047 nm

2,5-bis (N-methyl-4-pyridini)
Um) thiophene dibromide synthesis In a three-necked flask equipped with a condenser condenser and a condenser tube for cold methanol, 100 mg (0.42 mmol) of 2,5-bi- (4-pyridyl) thiophene and 7 ml of dry acetonitrile were placed. Then, 2 ml of methyl bromide was added. The mixture was reacted at 40 to 45 ° C. for 7 hours and 30 minutes with stirring, then the reaction mixture was cooled to room temperature, and the precipitated crystals were separated by filtration.

The precipitated crystals were thoroughly washed with acetonitrile and ether to obtain 180 mg of 2,5-bis (N-methyl-4-pyridinium) thiophene dibromide shown in Chemical formula 7 as pale yellow crystals. Further, by recrystallizing this crystal from ethanol, 2,5-bis (N-methyl-
A pure product of 4-pyridinium) thiophene dibromide was obtained.

<Physical data of 2,5-bis (N-methyl-4-pyridinium) thiophene dibromide> 1. Melting point: 300 ° C or higher (pale yellow needle crystal) 2. Electronic spectrum: in H ₂ O λ _max nm (log ε) 243 (3.91), 281 (3.83), 370
(4.56) 3. IR (KBr): cm ^-1 3030, 1637, 1541, 1473, 1340,
1294 1236, 1194, 820 4. ¹ HNMR: in D ₂ O at 200 Hz (δ in
ppm, J in Hz) 4.58 (6H, s, NMe) 7.97 (2H, s) 8.14 (4H, d, J = 7.0) 8.60 (4H, d, J = 7. 0)

2,5-bis (N-heptyl-4-pyridy
Synthesis of ( nium) thiophene dibromide 2,5- bi- (4-pyridyl) thiophene 250 mg
(1.05 mmol), heptyl bromide 752 mg (4.
(20 mmol) and 18 ml of dry acetonitrile were heated and refluxed for 5 days to react.
The reaction mixture was cooled to room temperature, the solvent was distilled off, and the residue was washed successively with ether and hexane,
630 mg of 2,5-bis (N-heptyl-4-pyridinium) thiophene dibromide shown in Chemical formula 8 above was obtained.

The obtained 2,5-bis (N-heptyl-4)
-Pyridinium) thiophene dibromide was obtained by recrystallizing from acetonitrile to give a melting point of 237-23.
It became dark yellow needle crystals at 8 ° C, and was obtained as a pure product.

<Physical data of 2,5-bis (N-heptyl-4-pyridinium) thiophene dibromide> 1. Melting point 237 to 238 ° C (deep yellow needle crystals) 1. Electronic spectrum: in H ₂ O λ _max nm (log ε) 373 (4.63), 282 (3.81), 244
(3.92) 3. IR (KBr): cm ^-1 3028, 2974, 2925, 1630, 1535,
1466 1350, 1294, 1232, 1169, 881, 8
41, 731 4. ¹ HNMR: in CF ₃ COOD at 200 Hz (δ in
ppm, J in Hz) 0.94 ( 6H, s, -CH 3) 1.44 (16H, mc, -CH 2 -) 2.17 (4H, mc, -N-CH 2 CH 2 -) 4. 64 (4H, mc, -N- CH 2 -) 8.17 (2H, s) 8.40 (4H, d, J = 6.5) 8.79 (4H, d, J = 6.5)

2,5-bis (N-cyanomethyl-4-pi)
Synthesis of ridinium) thiophene diiodide 2,5- bi- (4-pyridyl) thiophene 100 mg
(0.42 mmol) and acetonitrile iodide 280 m
The mixture obtained by adding g (1.67 mmol) to dry acetonitrile was heated and refluxed for 30 hours to react.

The reaction mixture was cooled to room temperature, the precipitated crystals were separated by filtration, and the crystals were washed with ether to give 2,5-bis (N-cyanomethyl-4-) shown in Chemical formula 9 above.
242 mg of pyridinium) thiophene diiodide were obtained. The obtained 2,5-bis (N-cyanomethyl-4-pyridinium) thiophene diiodide is further recrystallized from a water-acetone mixed solvent to give a melting point of 234 to
Purified as deep orange brown crystals at 235 ° C.

<2,5-bis (N-cyanomethyl-4-)
Physical data of pyridinium) thiophene diiodide> 1. Melting point 234 to 235 ° C (deep orange brown crystals) 1. Electronic spectrum: in H ₂ O λ _max nm (log ε) 226 (4.49), 284 (3.89), 384
(4.64) 3. IR (KBr): cm ^-1 3028, 1628, 1535, 1466, 1292,
1190, 816 4. ¹ HNMR: in CD ₃ CN at 200 Hz (δ i
n ppm, J in Hz) 5.58 (2H, s, CH ₂ ) 8.20 (2H, s) 8.33 (4H, d, J = 7.0) 8.78 (4H, d, J = 7.0)

Combination of 2,5-bi- (4-pyridyl) furan
Under it formed a stream of argon, 2,5-dibromo-franc 1.36g
(6.01 mmol) and 4-stannylpyridine 3.20
g (13.23 mmol) was dissolved in 54 ml of dry toluene, to which Pd (PPh ₃ ) ₄ 1.3
9 g (1.20 mmol) was added and the resulting mixture was heated to reflux for 4 hours.

After cooling the reaction solution to room temperature, 200 ml of chloroform was added, and the organic layer was first mixed with 1NNH.
_The extract was washed with an aqueous ₄ OH solution, then with water and then with saturated saline, and dried over anhydrous sodium sulfate. The solvent was distilled off, the residue was subjected to silica gel chromatography and eluted with acetone, and the obtained yellow crystals were dissolved in tetrahydrofuran (THF).
After purification by gel permeation chromatography (GPC) and elution with acetone again by silica gel chromatography, 633 mg of 2,5-bi- (4-pyridyl) furan shown in Chemical formula 10 above (yield 48%) was obtained. Was obtained as colorless crystals. The obtained 2,5-bi- (4-
By further recrystallizing pyridyl) furan from acetonitrile, colorless silky needle-like crystals having a melting point of 176 to 177 ° C. were obtained and obtained as a pure product.

<Physical data of 2,5-bi- (4-pyridyl) furan> Melting point 176 to 177 ° C. (colorless needle crystals) 1. Electronic spectrum: in MeCN λ _max nm (log
ε) 226 (4.27), 325 (4.60), 340
(4.50) 3. IR (KBr): cm ^-1 1606, 1577, 1415, 1213, 1030,
985, 827 789, 696, 673 4. ¹ HNMR: in CDCl ₃ at 200 Hz (δ i
n ppm, J in Hz) 6.98 (2H, s) 7.57 (4H, dd, J = 4.6, 1.5) 8.64 (4H, dd, J = 4.6, 1.5) ) 5. ¹³ CNMR: in CDCl ₃ at 50 Hz (δ in
ppm) 110.8, 117.8, 136.6, 150.4, 1
52.2 6. DEI-MS 224 (M ⁺ +2, 1.2%), 223 (M ⁺ +1, ² )
2.3%) 222 (M ⁺ , 100%), 221 (M ⁺ -1,1.4)
%)

2,5-bis (N-methyl-4-pyridini)
Um) Furan bistetrafluoroborate synthesis Under a stream of argon, 70 mg (0.32 mmol) of 2,5-bi- (4-pyridyl) furan was added to dry acetonitrile 6
Add milliliter and heat to 40-45 ° C for 2,5-
Bi- (4-pyridyl) furan was completely dissolved in acetonitrile.

To this solution was added 186 mg (1.26 mmol) of trimethyloxyfluoroborate (Me ₃ O ⁺ BF ₄ ⁻ ) all at once, and then the mixture was heated to 90 ° C. and stirred for 2 hours for reaction. The reaction mixture is cooled to room temperature and acetic acid 1
After adding ˜2 ml, 10 ml of dry ether was added, and the precipitated crystals were separated by filtration.

The obtained crystals were ethered to give 2,5-bis (N-methyl-) shown in Chemical formula 11 as yellow crystals.
134 mg of 4-pyridinium) furanbistetrafluoroborate were obtained. When the obtained 2,5-bis (N-methyl-4-pyridinium) furan bistetrafluoroborate was further recrystallized from water, it became a yellow silk-like needle crystal having a melting point of 300 ° C or higher, which was a pure product.

<Physical data of 2,5-bis (N-methyl-4-pyridinium) furan bistetrafluoroborate> 1. Melting point: 300 ° C or higher (yellow needle crystals) 2. Electronic spectrum: in MeCN λ _max nm (log
ε) 384 (4.65), 368 (4.61), 304
(3.76) 3. IR (KBr): cm ^-1 1635, 1587, 1566, 1508, 1485,
1336 1296, 1219, 1188, 1074, 1066
856, 822 4. ¹ HNMR: in CF ₃ COOD at 200 Hz (δ in
ppm, J in Hz) 4.11 (6H, s, NMe) 7.39 (2H, s) 8.08 (4H, br.d, J = 7.0) 8.38 (4H, br.d, J = 7.0) 5. ¹³ CNMR: in CF ₃ COOD at 50 Hz (δ in pp
m) 49.5 (NMe), 121.2, 124.4, 14
5.8 147.4, 154.3 6. Electronic spectrum of radical cation: in MeCN 561 nm, 962 nm, 1124 nm

Electrochemical Properties of Representative Compounds Among the compounds obtained above, 2,5-bis (N
-Methyl-4-pyridinium) thiophene tetrafluoroborate, 2,5-bis (N-cyanomethyl-4-pyridinium) thiophene tetrafluoroborate and 2,5-bis (N-methyl-4-pyridinium) furanbistetrafluoroborate The first reduction potential E ₁ ^1/2 , the second reduction potential E ₂ ^1/2 , the difference ΔE (= E ₁ ^1/2 −E ₂ ^1/2 ), log
K _sem was measured. The results are shown in Table 1.

[0059]

[Table 1]

Table 1 also shows the measurement results of methylviologen for comparison, and each compound to which the present invention is applied shows electrochemical characteristics comparable to those of methylviologen and has a large absorption coefficient ε. Therefore, it can be seen that it is very useful as an electrochromic material.

[0061]

As is clear from the above description, the compound of the present invention (bipyridinium salt extended with a five-membered heterocyclic ring) is used in the development of viologen as a material for information recording systems and light energy conversion systems. The drawbacks pointed out in 1. are improved, and new properties not found in viologen are exhibited.

Therefore, the compound of the present invention can be widely utilized for future advanced technology development, and is very useful, for example, as an electrochromic material.

[Brief description of drawings]

FIG. 1 shows an X-ray crystallographic analysis result of 2,5-bis (N-methyl-4-pyridinium) thiophene tetrafluoroborate, which is 2,5-bis (N-methyl-4).
It is a schematic diagram which shows the planar structure of -pyridinium) thiophene.

FIG. 2 is a schematic diagram showing a state of 2,5-bis (N-methyl-4-pyridinium) thiophene tetrafluoroborate viewed from the side.

FIG. 3 is a schematic diagram showing a layer state of 2,5-bis (N-methyl-4-pyridinium) thiophene tetrafluoroborate.

Claims (2)

[Claims] 1. The following chemical formula 1 (wherein X is S, O,
It is Se or N—CH ₃ , and R is an alkyl group having 1 to 18 carbon atoms, an alkylthiomethyl group, an alkoxymethyl group, a cyanomethyl group, a benzyl group, an alkoxycarbonyl group, a formyl group or a cyano group. ) A bipyridinium salt expanded with a hetero five-membered ring. [Chemical 1] 2. The following chemical formula 2 (wherein X is S, O,
It is Se or N-CH _3. ) A method for producing a bipyridinium salt extended with a five-membered heterocycle, which comprises introducing a substituent onto each N atom of the bipyridines represented by [Chemical 2]