JPH0723361B2 - Novel viologen derivative and its use - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel viologen derivative, a method for producing the same, an intermediate for producing the same, and an electrochromic composition using the above viologen derivative as a coloring species.

(Prior Art) Viologen is a general term for N-substituted quaternary compounds of 4,4'-dipyridyl represented by the following general formula (X).

In the above general formula (X), R represents an organic group and X ⁻ represents a counter anion.

The conventionally known viologen has a substituent in the nitrogen atom of the dipyridyl ring as shown in the above general formula (X). Very few examples have substituents other than the above compounds, RD Balanson, MEOxsen and YY Cheng et al. J. Chem.
Soc. Perkin Trans.I, 2704 (1979), 2,2'-dimethyldipyridinium salt, 2,2'-diethyldipyridinium salt, 2,2'-bis (4-chlorobutyl) dipyridinium salt and JA Barltrop AC Jackson et al. J. Chem. Soc. Perkin
The 2-methyldipyridinium salt and 2'-ethyldipyridinium salt shown in Trans.II, 367 (1984) are only known.

These viologen derivatives are characterized by showing a two-stage redox reaction as shown below.

In the above reaction, the redox of the cation and the cation radical in the first step is excellent in reversibility, and the cation radical exhibits strong coloring. Since this reaction can be performed electrochemically or photochemically, this property can be used for a wide range of applications such as electronic displays, wet solar cells, secondary batteries, silver salt or non-silver salt photographs, redox indicators, and photochromic materials. Is being studied. Furthermore, studies on biological reactions involved in redox in vivo and studies on pesticides such as herbicides have been conducted as its application.
In, dimethyl viologen with R ¹ = R ² = CH ₃ has been put to practical use as a pesticide paraquat.

(Problems to be Solved by the Invention) The redox potential (first redox potential) between the dication and the cation radical of the conventionally known viologen derivative is base, and is usually in the range of -0.5 to 1.0 V (SCE). Moreover, there is a problem that cation radicals are easily oxidized by oxygen in the air into dications and lack in stability. Especially when used in electrochromic displays, this drawback is a major obstacle to coloring stability. The first redox potential can be made noble to some extent by making R of the N substituent of the dipyridine ring an electron absorbing substituent, but it is still not sufficient.

(Means for Solving the Problem) The present inventors have found that the above problem can be solved by substituting a cyano group at the 2-position of the dipyridine ring of the viologen derivative.

The present invention has the following general formula (I) (In the general formula (I), R ¹ and R ² are selected from an alkyl group having 1 to 18 carbon atoms, a benzyl group which may have a substituent and a phenyl group which may have a substituent. R ¹ and R ² may be the same as each other. X ⁻ represents a counter anion) and a method for producing the same. The present invention provides an electrochromic composition containing an intermediate for producing a derivative and the above viologen derivative as a coloring species.

In the present invention, R ¹ and R ² in the general formula (I) are N substituents known as conventional viologen derivatives,
For example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, isopentyl, hexyl, 2
-Hexyl, heptyl, 2-heptyl, octyl, 2-octyl, nonyl, 2-nonyl, decyl, 2-decyl, undecyl, 2-undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, etc. And alkyl groups having 1 to 18 carbon atoms, preferably alkyl groups having 1 to 8 carbon atoms, benzyl, nitrobenzyl, cyanobenzyl, halogen-substituted benzyl, benzyl groups such as methylbenzyl, methoxybenzyl and dinitrobenzyl, or substituted benzyl groups. . Also
X ⁻ is a counter anion, and is not limited in the present invention due to the nature of the invention, but representative ones include Cl ⁻ and B.
r ^-, I ^- halogen anion such _{^{as, ClO 4 -, BF 4 -}} , NO 3 -, S
There are inorganic anions such as O ₄ ²⁻ and PO ₅ ²⁻ , organic sulfonate anions such as toluene sulfonic acid, and polymer anions such as polyvinyl sulfonic acid, polystyrene sulfonic acid, and polyperfluorosulfonic acid.

The viologen derivative of the present invention acts a compound represented by the following general formula (III) on an N-substituted 4- (4 ′-(2′-cyanopyridyl))-pyridinium salt represented by the following general formula (II). And quaternizing the nitrogen of the other pyridine.

(In the general formula (II), R ¹ and X ^- is R ¹ and X of the general Formulas (I) ^- represents the same as the meaning) in R ² X ¹ (III) (the general formula (III), R ² has the same meaning as R ^{2 in} formula (I), X ¹ is a halogen atom such as Cl, Br, I, p-
It is a group selected from a fluorosulfonic acid group, a toluenesulfonic acid group, a trifluorotoluenesulfonic acid group and a methylsulfonic acid group.) The above reaction is usually carried out in a polar solvent such as acetonitrile, dimethylformamide, dimethyl sulfoxide, tetrahydrofuran. , Dichloromethane, Chloroform, etc. in a solution or slurry under normal pressure or pressure (40 ~
160 ℃). When the compound of the general formula (III) is a liquid, it can be reacted without a solvent. When the compound of the general formula (III) is an alkyl halide, it is a reaction known as a so-called Menschutkin reaction (hereinafter, referred to as a Menschutkin reaction including a case where a compound other than the alkyl halide is used). is there). The produced viologen derivative (I) is generally insoluble in an organic solvent and precipitates from the reaction solution. When the precipitation property is not good, the counter anion can be exchanged for perchlorate ion from a water or alcohol solution for precipitation and purification.

In the above reaction, X ¹ of the general formula (III) compound becomes a counter anion of the general formula (I) compound after quaternization. These counter anions can be easily exchanged with desired anions by a conventional ion exchange method.

Specific examples of the general formula (III) compound include methyl bromide, ethyl bromide, propyl bromide, butyl bromide, isobutyl bromide, heptane bromide, hexane bromide, heptyl bromide, heptyl chloride, octyl bromide, nonane chloride, decane bromide, oleyl. Bromide, stearyl bromide, benzyl bromide, benzyl chloride, 4-cyanobenzyl bromide, 4-nitrobenzyl bromide, methylbenzyl bromide, dimethylsulfate, methyl p-toluenesulfonate, methyl p-fluorosulfonate, methyl trifluorotoluenesulfonate And so on.

Another method for producing the viologen derivative represented by the general formula (I) of the present invention is represented by the following formula (IV) It can be obtained by reacting 2-cyano-4,4'-dipyridine represented by with a compound represented by the following general formula (V) to quaternize the nitrogen of dipyridine.

The above reaction is usually carried out in a polar solvent under normal pressure or pressure at 40 to 160
The reaction is carried out at 0 ° C., but when 2-cyano-4,4′-dipyridine is soluble in the compound of the following general formula (V), it can be reacted without a solvent.

R'X ¹ (V) (In the general formula (V), R'is R ¹ or R ^{2 in the} general formula (I).
Represents a group similar to, X ¹ is a halogen atom such as Cl, Br, I,
It is a group selected from a p-fluorosulfonic acid group, a toluenesulfonic acid group, a trifluorotoluenesulfonic acid group and a methylsulfonic acid group.) In the present invention, the reaction proceeds in two steps.

R ^1, R ² of ^{R 1 X 1, R 2 X} 1 in the above reaction is an N-substituted group R ^1, R ² and becomes group in the general formula (I). X ¹ becomes a counter anion after quaternization. The counter anion can be easily exchanged with a desired anion by a conventional ion exchange method.

In the above reaction, if the reaction is stopped in the first step, the compound of the general formula (II), which is a raw material for synthesizing the viologen derivative of the present invention, can be obtained. If the kind of the compound of the general formula (V) is changed in the reaction of the second step, R ¹ and R ² of the general formula (I) are changed.
Different viologen derivatives can be obtained.

As the reaction solvent in the above reaction, dimethylformamide, acetonitrile, nitromethane, nitropropane,
Examples include sulfolane, chloroform and methylene chloride.

Specific examples of the compound represented by the general formula (V) include the compounds listed in the general formula (III).

In the present invention, 2-cyano-4,4'-dipyridine represented by the above formula (IV) is derived from N-methoxy-4 (4'-pyridyl) pyridinium salt. Further, the N-methoxy-4 (4′-pyridyl) pyridinium salt is, for example,
R. Fielden and LA Summers et al. J. Heterocyclic Chem. 11 , 2
It can be obtained by the method of semi-decomposing the N, N-dimethoxy-4,4'-dipyridinium salt reported in 99 (1974).

The method for synthesizing the compound of formula (IV) is as follows.

The compound of formula (IV) is obtained by reacting N-methoxy-4 (4'-pyridyl) pyridinium salt with potassium cyanide or sodium cyanide. Raw material N
-Methoxy-4 (4'-pyridyl) pyridinium salt is
Perchlorates, methylsulfates or halide salts are preferred, but not limited to.

The viologen derivative of the present invention exhibits electrochromism (coloring) by applying a voltage thereto in combination with a suitable supporting electrolyte in an aqueous solvent or an organic solvent such as propylene carbonate or dimethylformamide. Utilizing this phenomenon, the viologen derivative of the present invention can be applied to various display devices.

As the supporting electrolyte, salts of alkali metals and inorganic acids such as sodium chloride, sodium sulfate, and sodium hydrogen phosphate are preferable in an aqueous system, and lithium perchlorate, tetra-n-butylammonium perchlorate, tetrafluoro in an organic system. Salts of perchloric acid and tetrafluoroboric acid with lithium, quaternary ammonium such as tetra-n-butylammonium borate are preferred, and good electrochromism is obtained by these.

(Example) Example 1 N-methoxy-4 (4'-pyridyl) pyridinium perchlorate (200 mg) was added to a solution of potassium cyanide (200 mg) in water (10 ml) with stirring, and the temperature was maintained at 0 ° C for reaction for 1 hour. . The white precipitate formed was collected by suction filtration, dried, and purified by silica gel column chromatography to obtain 76 mg of white crystals of 2-cyano-4,4'-dipyridine.

mp 208 ° C (decomposition) Elemental analysis C ₁₁ H ₇ N ₃ C H N Calculated value (%) 72.91 3.90 23.19 Measured value (%) 72.85 3.72 23.47 ¹ H-NMR (CDCl ₃ ) δppm: 7.86 (2H, dd), 8.12 (1H, dd), 8.37 (1H, dd), 8.78 (2H, dd), 8.88 (1H, dd) ¹³ C-NMR (CDCl ₃ ) δppm: 122.29,125.85, 127.43,135.57, 144.04,147.90, 151.82 , 151.88, 152.93 IR (KBr) 1 / λcm ^-1 3040, 2230, 1588, 1396, 986, 819 Example 2 181 mg of 2-cyano-4,4'-dipyridine obtained in Example 1 and 568 mg of methyl iodide were dissolved in 5 ml of acetonitrile and refluxed for 1 week to react. Excess methyl iodide and acetonitrile were distilled off under reduced pressure, and the residue was treated with an ion exchange resin (Dowex 2 × 8: manufactured by Dow Chemical Co.) to exchange iodine ion with chlorine ion, and N, N′- Dimethyl-2-cyano-4,4'-dipyridinium dichloride 2
20 mg was obtained.

¹ H-NMR (D ₂ O) δppm: 4.56 (3H, s), 4.72 (3H, s), 8.60 (2H, d), 8.89 (1H, dd), 9.14 (2H, d), 9.26 (1H, d), 9.44 (1H, d ) the redox potential _{^{E 1 1/2 = -390mV, E 2}} 1/2 = -720 mV (1MKCl, SCE) N obtained by example 3 example 2, N'Dimethyl-2-cyano-4,4'-dipyridinium dichloride 20 mg was added to 0.1 M KCl
Dissolve in 5 ml of aqueous solution and use indium-tin oxide coated transparent glass electrode (ITO electrode) as working electrode, platinum plate as counter electrode, saturated calomel electrode (SC) as reference electrode.
The above aqueous solution was degassed and enclosed in an electrochemical cell prepared using E). When a negative voltage of -400 mV was applied to the ITO electrode, it was colored blue. Redox potential is E ¹ _1/2 = -390m
V, E ² _1/2 = −720 mV (vsSCE).

Example 4 20 mg of N, N'-dimethyl-2-cyano-4,4'-dipyridinium dichloride obtained in Example 2 was dissolved in 1 ml of water, and 5 ml of concentrated perchloric acid was added dropwise. The reaction solution immediately became cloudy and a white crystalline precipitate was obtained after 1 hour. The precipitate was collected by suction filtration and, after drying, 22 mg of N, N'-dimethyl-2-cyano-4,4'-dipyridinium perchloric acid was obtained.

¹ H-NMR (DMF) δppm: 4.52 (3H, s), 4.71 (3H, s), 8.80 (2H, d), 9.09 (1H, dd), 9.35 (2H, d), 9.52 (1H, d) , 9.70 (1H, d) Elemental analysis C ₁₃ H ₁₃ Cl ₂ N ₃ O ₈ C H Cl N Calculated value (%) 38.1 3.2 17.3 10.3 Measured value (%) 38.0 3.1 17.2 10.3 Example 5 2-Cyano-4,4'-dipyridine (181 mg) obtained in Example 1 and methyl iodide (156 mg) were dissolved in acetonitrile (5 ml), and the mixture was refluxed for 1 day for reaction. Acetonitrile was distilled off under reduced pressure, the residue was dissolved in 5 ml of water, and 0.5 ml of concentrated perchloric acid was added thereto, whereby a white precipitate was produced. This precipitate was collected by filtration and dried to obtain 510 mg of N-methyl-4- (4 '-(2'-cyanopyridyl))-pyridinium perchloric acid.

¹ H-NMR (aceton-d ⁶ ) δppm: 4.70 (3H, s), 8.36 (1H, dd), 8.60 (1H, dd), 8.74 (2H, dd), 9.02 (1H, dd), 9.29 (2H) , d) 510 mg of the above-obtained N-methyl-4- (4 '-(2'-cyanopyridyl))-pyridinium perchlorate was dissolved in 5 ml of acetonitrile, 312 mg of methyl iodide was added, and the mixture was refluxed for 1 week for reaction. . Excess methyl iodide and acetonitrile are distilled off under reduced pressure, and the residue is treated with an ion exchange resin (Dowex 2x8: Dow Chemical Co.) to exchange iodine ion and perchlorate ion with chlorine ion. N, N′−
220 mg of dimethyl-2-cyano-4,4'-dipyridinium chloride was obtained. The ¹ H-NMR data of this product was the same as the product of Example 2.

Example 6 A solution of 181 mg of 2-cyano-4,4'-dipyridine obtained in Example 1 and 197 mg of heptyl bromide in 20 ml of acetonitrile was refluxed for 1 week to react with N-heptyl-4.
47 mg of-(4 '-(2'-cyanopyridyl))-pyridinium bromide was obtained.

¹ H-NMR (D ₂ O) δppm: 0.65 (7H, b), 1.12 (4H, m), 1.93 (2H, m), 4.81 (2H, t), 8.35 (1H, dd), 8.61 (1H, dd), 8.74 (2H, dd), 9.00 (1H, dd), 9.22 (2H, dd) 47 mg of the N-heptyl-4- (4 '-(2'-cyanopyridine))-pyridinium bromide obtained above was dissolved in 1 ml of dimethyl sulfate and reacted at 120 ° C for 15 minutes. After the reaction, this was cooled, 10 ml of ethanol was added, and concentrated perchloric acid was 0.5 ml.
Is added to N'-heptyl-N-methyl-2-cyano-
32 mg of 4,4'-dipyridinium perchlorate was obtained as a white precipitate.

¹ H-NMR (DMSO-d ⁶ ) δppm: 0.6 (7H, b), 1.09 (4H, m), 1.90 (2H, m), 4.60 (3H, s), 4.72 (2H, t), 8.80 (2H) , d), 9.05 (1H, dd), 9.30 (2H, d), 9.54 (1H, d), 9.62 (1H, d), Example 7, Comparative Example 1 N, N ′ obtained in Example 4 -Dimethyl-2-cyano-4,
20.5 mg of 4'-dipyridinium diperchlorate was dissolved in 5 ml of dimethylformamide to prepare a 10 mmol / l solution, and 171 mg of tetra-n-butylammonium perchlorate as a supporting electrolyte was added thereto to obtain 0.1 mol. / l solution.

This solution was enclosed in an electrochemical cell prepared by using a ITO plate as a working electrode, a platinum plate as a counter electrode, and SEC as a reference electrode. Next, cyclic voltammograms of these electrochemical cells were measured, and the first redox potential was determined and shown in Table 1. Furthermore, when a voltage more negative than the first redox potential was applied to the ITO electrode, the ITO electrode was strongly colored by the viologen cation radical generated by the reduction. These colors are also shown in Table 1.

In addition, as a comparative example, 2 of the viologen derivative of Example 4 was used.
The same measurement was performed for a compound having no cyano group at the -position.

The sample-enclosed cells of the above-mentioned Examples and Comparative Examples were both colorless and transparent before applying a negative voltage.

As is clear from Table 1, the viologen derivatives of Examples of the present invention have a first redox potential of 200 to 3 as compared with the corresponding compound of Comparative Example 1 having no cyano group at the 2-position.
00mV is precious. Therefore, the cation radicals produced electrochemically are not easily oxidized by oxygen in the air, and more stable electrochromic display is performed.

(Effects of the Invention) The cyano-substituted viologen derivative of the present invention has a noble redox potential as compared with the corresponding conventional unsubstituted or alkyl-substituted viologen derivative, and therefore is less likely to be oxidized by oxygen in the air, Gives a more stable electrochromic display.

Claims (6)

[Claims] 1. A viologen derivative represented by the following general formula (I). In the general formula (I), R ¹ and R ² are each a substituent or a substituent selected from an alkyl group having 1 to 18 carbon atoms, a benzyl group or a nitro group, a cyano group, a halogen atom, a methyl group and a methoxy group. And R ¹ and R ² may be the same group. X ^- represents a counter anion. 2. In producing the viologen derivative represented by the general formula (I) according to claim 1, the following general formula (I
I) (In the general formula (II), R ¹ and X ^- R ¹ and X of the general Formulas (I) ^- represents the same meaning as) N- substituted represented by 4- (4 '- (2'-cyano pyridyl)) - pyridinium salt, in the following general formula ^{(III) R 2 X 1 (} III) ( the general formula (III), R ² represents the same meaning as R ² in formula (I), X ¹ Is a group selected from a halogen atom, a p-fluorosulfonic acid group, a toluenesulfonic acid group, a trifluorotoluenesulfonic acid group and a methylsulfonic acid group). 3. In producing the viologen derivative represented by the general formula (I) according to claim 1, the following formula (IV) 2-cyano-4,4'-dipyridine represented by the following general formula (V) R'X ¹ (V) (in the above general formula (V), R'is R ¹ or R in the general formula (I)). ²
X ¹ is a group selected from a halogen atom, a p-fluorosulfonic acid group, a toluenesulfonic acid group, a trifluorotoluenesulfonic acid group, and a methylsulfonic acid group). A manufacturing method characterized by: 4. N-substituted 4 represented by the following general formula (II):
-(4 '-(2'-cyanopyridyl))-pyridinium salt. (In the general formula (II), R ¹ represents the same meaning as R ¹ in the general formula (I), X ^- represents a counter anion) 5. 2-Cyano-4 represented by the following formula (IX):
4'-dipyridine. 6. An electrochromic composition comprising a viologen derivative represented by the general formula (I) according to claim 1 as a coloring species.