JPH0795167B2 - Complex film coated element and method of using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel complex film coated element capable of expressing a potential gradient by applying a voltage and a method of using the same.

[Conventional technology]

An attempt to actively use polymer compounds for chemical modification of the electrode surface was started in 1977-8, and researchers from not only the electrochemical field but also other fields have joined to create a new trend. . It is conventionally known that an electrode is covered with a complex film and a specific electronic state or potential state is induced in the complex film by applying a voltage, and this principle has been used for an electrochromic display element and the like. However, a conductive wire is provided at both ends of a conductive support coated with a complex film, and this is used as an element, and a voltage is applied to this element to generate a continuous potential gradient, and the absorption spectrum of the complex film, the magnetic field It was not known to express by continuous changes in properties, reactivity, etc.

[Problems to be solved by the invention]

Hitherto, no means has been known for expressing potential changes continuously by color changes or the like. Therefore, the present invention provides an element used for an indicator or the like that can express a potential gradient.

[Means for solving problems]

The present invention relates to a complex film-covered element in which conductive wires are provided at both ends of a conductive support which is partially or wholly coated with a complex film.

The present invention also provides a complex film-covered element, which is provided with conductive wires at both ends of a conductive support partially or wholly coated with a complex film, between the conductive wires at both ends of the complex film-coated element. The present invention relates to a method of continuously changing the electronic state of the complex film according to a potential gradient by applying a voltage under the condition of impregnating the liquid.

In the present specification, an element refers to a passive element that exists as a constituent element having a specific function in an electric circuit and exhibits the function when energized.

Hereinafter, the device of the present invention and the method of using the device will be described in detail.

(Support) The conductive support used in the element of the present invention usually has a resistance value of 10
^It is a conductive substance of ^-2 to 10 ⁴ ohms, preferably 10 ¹ to 10 ² ohms, and it is preferable to use, for example, Nesa glass, graphite or other conductive polymer substances. The shape may be any shape as long as it has conducting wires at both ends and can conduct electricity.
A support having an arbitrary width of 1 mm to 1 m can be used.

To apply an appropriate voltage, if the conductivity is too high, an excessive current will flow, which is not preferable. On the other hand, since a redox reaction or a doping / dedoping reaction of the complex film is performed to change the electronic state of the complex film, an appropriate electric current needs to flow through the support, and it is not preferable that the conductivity is too low. . That is, it is necessary to use a support material having an appropriate conductivity depending on the size of the support, the type and thickness of the complex film, the voltage to be applied, and the like. For example, it is preferable to use a support having a resistance value of about 1 to 100 ohms, for example, Nesa glass (InSnO ₂ coated glass) or the like, for an element having a length of several centimeters between both ends of the conductive wire.

(Complex film) As the complex film that can be used in the present invention, 1) a film of a polynuclear metal complex, 2) a film of an organic or inorganic polymer compound containing a complex, and 3) application of an appropriate voltage, There are three types of films, that is, an organic polymer compound film in which ions or cations are doped or dedoped into the film to form a complex state specific to the voltage, and the film thickness is preferably about 0.05 to 100 μm.

Hereinafter, these complex films and the formation method thereof will be described in detail.

1) Film of polynuclear metal complex A film of the polynuclear metal complex that can be used in the present invention is a film of a polynuclear metal complex represented by the following composition formula (i), which is electrodeposited on a support.

(M _I ^{l +} ) _x [M _II ^{m +} (CN) ₆ ] _y · _z H ₂ O (i) However, M _I and M _II may be the same or different. Periodic Table VIA, VIIA , VIII, IB, IIB, and IVB, a metal ion selected from the group consisting of the following, 1 and m are valences of the metal ion, x and y are integers from 1 to 4, and z
Is an integer of 0 or 1 or more, and l, m, x, and y satisfy the following relational expression (a).

lx = y (6-m) (a) As a typical example of the polynuclear metal complex represented by the composition formula (I), Prussian blue (hereinafter abbreviated as PB): (Fe
³⁺ ) ₄ [Fe ²⁺ (CN) ₆ ) ₃ ⁴ -.zCH ₂ O can be mentioned.

PB but is a mixed-valence complex of Fe ²⁺ -Fe ^3+, when reduced to (hereinafter abbreviated as PW) Prussian white Fe ²⁺ -Fe ²⁺ becomes, is oxidized in the opposite Fe ³⁺ -Fe ^{3 +} Berlin Green (abbreviated as BG below). PB is such PW-PB-
It can take continuous electronic states between BGs.

The polynuclear metal complex can be easily obtained as a coating film on the electrode by the electrodeposition method. Taking PB as an example, K ₃ [Fe (C
N) ₆ ] ³⁻ and FeCl ₃ aqueous solutions are mixed to prepare a BG aqueous solution, and an appropriate electrolyte such as KCl, K ₂ SO ₄ or HCl is added. A support to be coated on this (hereinafter referred to as working electrode), a reference electrode such as Ag-AgCl, and a platinum counter electrode are immersed,
A reduction potential (for example, −0.5 V with respect to the reference potential) is applied to the working electrode to reduce BG to PB, and at the same time, a PB film can be deposited on the working electrode.

The PB membrane-coated support thus prepared is immersed in water containing an electrolyte such as KCl or HCl, and a voltage is applied between the two lead wires previously attached at both ends. When Nesa glass with a resistance of 12 Ω is used as an electrode, applying 1.5 V between the conductors at both ends creates a potential gradient between both ends of the film, the film near the positive electrode is light brown (BG) and the film near the negative electrode is colorless ( PW), the middle is blue, and this color tone changes continuously from end to end. It can be seen that when the applied voltage was cut off, the film immediately turned blue (PB) over the entire surface and changed uniformly to PB.

2) Film of Organic or Inorganic Polymer Compound Containing Complex There are roughly two methods for forming a film of an organic or inorganic polymer compound containing a complex. One is a method of forming a polymer complex containing a complex group by a covalent bond on an electrode, and the other is a method of previously coating a film of an organic or inorganic polymer compound on the electrode and adsorbing the complex in the film. Is. An example of an organic polymer complex containing a complex group by a covalent bond is tris (2,2 ′
-Bipyridine) ruthenium (II) complex [Ru (bpy) ₃ ²⁺ ] is included in the homopolymer or copolymer, and its composition is represented by the formula (ii).

However, where M is a monomer unit, Is 2,2'-bipyridine, x, y, and z are repeating units, x is 0 to 0.99, y is 0 to 0.99, and z is 0.01 to 1.00.
Takes a value in the range.

In the composition formula (ii), M is styrene, acrylic acid, methyl methacrylate, hydroxyethyl methacrylate,
Vinyl pyridine etc. are mentioned.

Further, a polymer complex of poly (vinyl pyridine) and an ion or complex of copper, iron, cobalt, nickel or the like can be used. These polymer complexes can be easily formed into a film from a solution by a casting method, a spin coating method, or the like.

The method of pre-coating the organic polymer compound film on the support and then adsorbing the complex into the film is to use a polyanion or polycation as the polymer and pre-coat the polymer film by a casting method or a spin coating method. However, it is preferable to electrostatically incorporate a cation or anion type complex into this film. Examples of the polyanion include Nafion, poly (sodium styrenesulfonate), poly (sodium acrylate), and the like. Cationic complexes incorporated therein are Ru (bpy) ₃ ²⁺ , tris (o-phenanthroline) ruthenium ( II) complex, [Ru (NH ₃ ) ₆ ] ³⁺ , [(Bpy) ₂ Ru-O-Ru (bpy) ₂ ] ⁴⁺ , CdS, and the like are included, and viologens, cationic dyes such as thionine, and the like are incorporated to form an ionic complex. As the polycation, quaternized or protonated polyvinyl pyridine,
Examples include polymer Ru (bpy) ₃ ²⁺ complex of formula (ii), polymer pendant viologen, and laminated polycations such as polyxylyl viologen. CN) ₆ ] ^3- , [Fe (CN) ₆ ] ^4- , [Fe
(CN) ₅ Cl] ²⁻ , IrCl ₆ ³⁻ , Mo (CN) ₈ ⁴⁻ , [W (CN) ₈ ] ^{4− and the} like.

When an inorganic polymer compound film is used, typical examples of the inorganic polymer compound include clay such as kaolin, bentonite, and montmorillonite. A film can be formed by adding an aqueous suspension of these fine particles onto the electrode and drying.

Incorporation of a compound such as a complex into the film of these organic or inorganic polymer compounds can be easily carried out by immersing the film-coated electrode in a solution containing the compound to be adsorbed.

3) Membrane of organic polymer compound capable of doping / dedoping As a membrane of organic polymer compound capable of doping / dedoping, electrolytic polymerization such as a polymer of aniline, pyrrole, thiophene or a derivative thereof can be used. Examples of the obtained polymer film and films of polymers such as polyacetylene and poly (N-vinylcarbazole).

When the support coated with these polymer membranes is dipped in an electrolyte solution and an appropriate voltage in the range of -2 to 2V is applied, anions and protons are doped into the membrane or are removed from the membrane depending on the voltage. It is known that dedoping takes a complex state (electronic state) specific to the voltage. If such a polymer film is applied in the present invention, a film having a gradient of an electronic state corresponding to a potential gradient can be obtained as described above. Since the absorption spectrum changes depending on the electronic state, a film whose color tone changes continuously from one end to the other end is formed. Further, by utilizing anion doping of such a film under an anodic condition, an anionic complex or compound can be incorporated into the film as a dopant and can be used as a complex film in the present invention.

(Applying Voltage) In a state in which a voltage is applied to the device of the present invention to continuously change the electronic state according to the potential gradient in the complex film, between the components in different electronic states in the film. The electron transfer reaction at is always occurring. Such electron transfer reaction is
It occurs steadily either directly between adjacent components of the membrane or indirectly between distant components in the membrane, via the conduction of the support. Since the potential gradient is canceled by this electron transfer reaction, it is a requirement for maintaining the potential gradient that a current sufficient to overcome this is always applied from the outside.

Further, in the present invention, since it is necessary to cause the redox reaction and the doping / dedoping reaction of the membrane component, it is necessary that the membrane is in contact with or impregnated with the electrolyte solution. A simple method is to immerse the complex film-coated element in an electrolyte solution and apply a voltage. Water is usually used as the medium, but any medium that does not dissolve the complex film may be used.

The applied voltage depends on the chemical composition of the film, the thickness, the support material, etc., but the range of 0.01 to 10 V is suitable.

The present invention will be described below with reference to examples.

Example 1 Nesa glass having a length of 5.5 cm, a width of 0.5 cm and a thickness of 5.1 mm (resistance value 1
0 Ω) was used as a support, copper wires were attached to both ends of the support with silver epoxy, and the periphery thereof was fixed with insulating epoxy to prepare an electrode. This electrode (working electrode), the Ag-AgCl reference electrode, and the platinum plate counter electrode were replaced with K ₃ [Fe (CN) ₆ ] ³⁻ and FeCl ₃ respectively.
Immerse in an aqueous solution containing mM, apply a cathode voltage to one of the conductors of the working electrode, and carry out constant current electrolysis under the condition of 50 μA cm ^-2 .
A 1-2 μm PB film was reductively deposited on the working electrode.

The PB film-coated device of the present invention thus prepared was treated with 10 mM HCl.
When a voltage of 1.5 V is applied between the conducting wires attached to both ends of the device by immersing it in an aqueous solution containing 25 mM KCl and 25 mM KCl, PB near the positive electrode is oxidized to BG and turns yellow, and PB near the negative electrode is reduced. As a result, it became PW and became colorless, while PB remained in the vicinity of the center and became blue, and these color tones continuously changed from one end to the other end (see FIG. 1). The transmission visible absorption spectrum at each position of this film was measured and is shown in FIG. It can be seen that the spectrum changes continuously from end to end. Since the spectrum reflects the electronic state of the film, it can be seen that the electronic state of the film changes continuously from PW to PB to BG. This means that the film has an electronic state gradient under these conditions. 15mA under this condition
The current was constantly flowing.

When the applied voltage was cut off, the film immediately became all-blue PB. When the voltage was applied again, the film displayed the same potential gradient as that described above, and such changes in the film due to the application and interruption of the voltage were repeatedly reproduced.

Example 2 Ruthenium Purple (RP); a (Fe ³⁺⁾ ₄ [Ru ²⁺ (CN) _{6] 3} ⁴ the same electrode on as Example 1, K
_A film was deposited from a 1 mM mixed aqueous solution of ₃ Ru (CN) ₆ and FeCl _{3 by} the same electrolytic reduction method as in Example 1. This RP film-covered element was manufactured in the same manner as in Example 1, and 1.0 V was applied between the conductors attached to both ends.
Voltage is applied. The vicinity of the positive electrode became reddish purple, and the vicinity of the negative electrode became colorless, forming a film in which the color tone changed continuously from the positive electrode end to the negative electrode end, and the potential gradient was displayed.

Example 3 On the same electrode as in Example 1, a polymer pendant type Ru (bpy) ₃ ²⁺ complex in which M was styrene, x was 0.934, y was 0.033, and z was 0.033 in the composition formula (ii) was prepared. A DMF solution containing 1 mM Ru complex unit was added at a ratio of 32 μl cm ⁻² and uniformly spread, and then dried to form a film. When this coated element is immersed in an aqueous solution containing 50 mM HCl and a voltage of 1.8 V is applied between the conductors at both ends, the positive electrode turns green, the negative electrode turns red, and changes continuously from one end to the other. The color tone was changed to show that the potential gradient was displayed.

Example 4 An electrode similar to that of Example 1 was prepared by attaching two copper wires to both ends of a graphite plate electrode having a length of 7 cm and a width of 0.5 cm. When poly (4-vinylpyridine) quaternized with benzyl chloride was formed into a film from a DMF solution by a casting method on the surface of this electrode, it was immersed in an aqueous solution containing 10 mM of K ₃ [Fe (CN) ₆ ] ^{3 −.} ,
After 3 hours, [Fe (CN) ₆ ] ³⁻ was sufficiently adsorbed. By impregnating the membrane of this coated element with an aqueous solution containing 10 mM of KCl and applying 1.1 V between the two copper wires, the color near the positive electrode became brown or yellow and the color near the negative electrode became colorless, and this color tone changed continuously. Then, the potential gradient was displayed.

Example 5 Nafion was coated on the same electrode as in Example 1 as a film from a DMSO solution by a casting method, and the film-coated electrode was Ru (bpy) ₃
Ru (bpy) ₃ ²⁺ is adsorbed in the Nafion membrane by immersing it in an aqueous solution containing 2 ⁺ 5 mM and leaving it to stand overnight. When a voltage was applied using this in the same manner as in Example 3, the same color tone change as in Example 3 occurred, and the potential gradient was displayed.

Example 6 Nesa glass having a length of 4.5 cm, a width of 0.7 cm and a thickness of 5.1 mm (resistance value 2
0 Ω) was used to prepare an electrode similar to that of Example 1, and a suspension aqueous solution containing fine powder of kaolin at a rate of 0.1 g / 5 ml was added thereto at a rate of 75 μl cm ⁻² , spread and dried, A kaolin film was coated. This membrane-coated electrode The complex was immersed in an aqueous solution containing 5 mM to adsorb the Mn complex in the film. By applying a voltage of 1.4 V between the two conducting wires of this element, the positive electrode area becomes brown and the negative electrode area becomes green.
The potential gradient was displayed.

Example 7 The same electrode as used in Example 1 was used, and this was immersed in an aqueous solution containing 1M aniline and 2M HCl together with an Ag-AgCl reference electrode and a platinum plate counter electrode, and subjected to 1V (vs. Ag-AgCl) constant current electrolysis. An aniline was oxidatively polymerized to prepare a device coated with a polyaniline film. This membrane-coated electrode was mixed with 0.2M LiCl and 10mM HC.
When immersed in an aqueous solution containing l and applying 1.3 V between the two conductors, the area near the positive electrode turns purple to brown, the area near the center turns green to blue,
The area around the negative electrode turned yellow, and the device displayed an electric potential gradient.

〔The invention's effect〕

By using the complex film-coated element of the present invention by the method of the present invention, it is possible to generate an electronic state on the complex film that continuously changes according to a potential gradient.

Application to an indicator is a future issue, but for example, if it is a compound that can follow the progress of the reaction in a spectrum, it is adsorbed on a film and a voltage is applied, and the spectrum at each position of the element is covered from end to end. By measuring, it is possible to know at which potential the compound reacted, and to know the reactivity and redox potential of the compound.

[Brief description of drawings]

FIG. 1 shows an example of a device of the present invention coated with a PB film.
Is the position where the spectrum was measured,
Corresponds to ~ in the figure. When a voltage is applied, the complex film continuously changes from BG to PB to PW from the positive electrode end to the negative electrode end. FIG. 2 shows a continuous change in the visible absorption spectrum at each position up to when a voltage of 1.5 V was applied to the device shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Conductive wire, 2 ... Silver epoxy 3 ... Insulating epoxy 4 ... Support body covered with PB film (nesa glass)

Claims (10)

[Claims] 1. A complex film-covered element comprising a conductive support, which is coated with a part or the whole of a complex film, and conductive wires provided at both ends thereof. 2. The complex film-coated device according to claim 1, wherein the complex film is a film of a polynuclear metal complex represented by the following composition formula (i), which is electrodeposited on a support. (M _I ^{l +} ) _x [M _II ^{m +} (CN) ₆ ] _y · _z H ₂ O (i) However, M _I and M _II may be the same or different. Periodic Table VIA, VIIA , VIII, IB, IIB, and IVB, a metal ion selected from the group consisting of the following, 1 and m are valences of the metal ion, x and y are integers from 1 to 4, and z
Is an integer of 0 or 1 or more, and l, m, x, and y satisfy the following relational expression (a). lx = y (6-m) (a) 3. The complex film-covered element according to claim 1, wherein the complex film is a film of an organic polymer compound containing a complex. 4. The complex film-covered element according to claim 1, wherein the complex film is a film of an inorganic polymer compound containing a complex. 5. The complex film is an organic polymer compound in which an anion or a cation is doped or dedoped into the complex film by applying an appropriate voltage to take a complex state specific to the voltage. The complex film-covered element according to claim (1). 6. A complex film-covered element comprising a conductive support, which is partially or wholly coated with a complex film, provided with conductive wires at both ends thereof. A method of continuously changing the electronic state of the complex film according to a potential gradient by applying a voltage under the condition of impregnating the liquid. 7. The complex membrane is a membrane of a polynuclear metal complex represented by the following composition formula (i), which is electrodeposited on a support, and has a voltage of 0.5 to 10 V. Method described in section. (M _I ^{l +} ) _x [M _II ^{m +} (CN) ₆ ] _y · _z H ₂ O (i) However, M _I and M _II may be the same or different. Periodic Table VIA, VIIA , VIII, IB, IIB, and IVB, a metal ion selected from the group consisting of the following, 1 and m are valences of the metal ion, x and y are integers from 1 to 4, and z
Is an integer of 0 or 1 or more, and l, m, x, and y satisfy the following relational expression (a). lx = y (6-m) (a) 8. The method according to claim 6, wherein the complex film is a film of an organic polymer compound containing a complex and the voltage is 0.1 to 10V. 9. The method according to claim 6, wherein the complex film is a film of an inorganic polymer compound containing a complex and the voltage is 0.1 to 10V. 10. A complex film is an organic polymer compound in which an anion or a cation is doped or dedoped into the complex film by applying an appropriate voltage to obtain a complex state specific to the voltage. The method according to claim 6, wherein the voltage is -2 to 2V.