JP2010006758A - Luminescent ionic liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new ionic liquid having a high luminescence yield, especially having a high luminescence yield at a high temperature. <P>SOLUTION: This luminescent ionic liquid is expressed by general formula (I) [wherein Rs are each independently an alkyl]. The Rs in the general formula are each preferably a 1-8C alkyl. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel luminescent ionic compound.

  Since the report by Wilkes et al. In 1992, an ionic liquid has attracted attention as a substance that is liquid at room temperature and has excellent ionic conductivity. In the ionic liquid, the cation and the anion are combined by electrostatic attraction, the number of ion carriers is very large, and the viscosity is relatively low, so that the ion mobility is high even at room temperature. It has the characteristic that the property is very high. In addition, since the ionic liquid is composed only of cations and anions, the boiling point is high (above 300 ° C.) and the temperature range in which the liquid state can be maintained is very wide. Furthermore, since the ionic liquid has almost no vapor pressure, it has low flammability and excellent thermal stability (see Non-Patent Documents 1 and 2).

  Because of these various advantages, application of ionic liquids to electrolytes of non-aqueous electrolyte secondary batteries and electric double layer capacitors has recently been examined (see Patent Documents 1 and 2). When an ionic liquid is used as the electrolytic solution of the multilayer capacitor, the ionic liquid also functions as an ion source for forming an electric double layer, and thus there is an advantage that it is not necessary to add a supporting electrolyte separately. However, since the ionic liquid is a liquid at room temperature, it usually contains an organic group and has a risk of combustion.

  In contrast, JP 2007-153868 (Patent Document 3) discloses a structure in which a primary, secondary, or tertiary amine is bonded to a cyclic phosphazene compound as an ionic liquid having a very low risk of combustion. New substances have been reported.

  In recent years, luminescent ionic liquids have been reported, and such ionic liquids may be applicable to various uses (see Non-Patent Document 3).

J. Electrochem. Soc., 144 (1997) 3881 “Functional creation and application of ionic liquids”, NTS, (2004) JP 2004-111294 A JP 2004-146346 A JP 2007-153868 A A. Paul, P. K. Mandel and A. Samanta, Chem. Phys. Lett., 402, 375-379 (2005)

  However, as a result of investigations by the present inventors, it has been found that the luminescent ionic liquid described in Non-Patent Document 3 has a low emission yield, particularly a low emission yield at high temperatures.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and provide a novel ionic liquid having a high light emission yield, particularly a high light emission yield at a high temperature.

  As a result of intensive studies to achieve the above object, the present inventors have found that a novel substance having a structure in which a tertiary amine is bonded to a cyclic phosphazene compound and ion-exchanged with a bis (trifluoromethanesulfonyl) imide ion is ionic. At the same time, the inventors have found that the light emission yield is high, in particular, the light emission yield at high temperature is high, and the present invention has been completed.

［式中、Ｒはそれぞれ独立してアルキル基である］で表されることを特徴とする。 That is, the luminescent ionic liquid of the present invention has the following general formula (I):

[Wherein, each R is independently an alkyl group].

  In a preferred example of the luminescent ionic liquid of the present invention, R in the general formula (I) is an alkyl group having 1 to 8 carbon atoms.

  ADVANTAGE OF THE INVENTION According to this invention, the novel ionic liquid with a high luminescence yield, especially the luminescence yield at high temperature can be provided.

  The present invention is described in detail below. The luminescent ionic liquid of the present invention is represented by the above general formula (I). The ionic liquid of the formula (I) is a kind of cyclic phosphazene compound having a plurality of phosphorus-nitrogen double bonds and has an ionic substituent, and thus has ionicity. And since it has a phosphazene skeleton, it decomposes | disassembles at the time of combustion, generate | occur | produces nitrogen gas, phosphate ester, etc., and since this nitrogen gas, phosphate ester, etc. suppress the progress of combustion, the danger of combustion is low. In the ionic liquid, fluorine functions as a scavenger for active radicals in the unlikely event of combustion, further reducing the risk of combustion. Further, the ionic liquid contains an alkyl group and produces a carbide (char) during combustion, and has an oxygen blocking effect. Surprisingly, the ionic liquid of the present invention has a feature that it has higher luminescent properties than conventional ionic liquids, and particularly has high luminescent properties at high temperatures.

  R in the general formula (I) is each independently an alkyl group, preferably an alkyl group having 1 to 8 carbon atoms. When the number of carbon atoms in the alkyl group exceeds 8, the viscosity increases. Here, as the alkyl group in R, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, various pentyl groups, various hexyl groups, various heptyls Group, various octyl groups and the like. In the formula (I), each R may be the same or different.

The ionic substituent of the ionic liquid of formula (I) is formed by bonding —N ⁺ R ₃ and (CF ₃ SO ₂ ) ₂ N ⁻ mainly by electrostatic attraction. Therefore, the compound of formula (I) has ionicity.

The method for producing the ionic liquid of the present invention is not particularly limited. For example, in an organic solvent, the following chemical formula (II):
(NPR ¹ ₂ ) ₃ ... (II)
[Wherein ^one of six R ¹ is chlorine and five are fluorine], and a cyclic phosphazene compound represented by the following general formula (III):
NR ₃ ... (III)
[In the formula, each R is independently an alkyl group] By reacting with a tertiary amine represented by the following general formula (IV):
(NPR ² ₂ ) ₃ ... (IV)
[Wherein one of the six R ² is represented by the following general formula (V):
_{^{-N + R 3 Cl - ··· (}} V)
(Wherein each R is independently an alkyl group) and five are fluorine], and then in an organic solvent, An ionic compound represented by the above general formula (IV) and lithium bis (trifluoromethanesulfonyl) imide [LiN (SO ₂ CF ₃ ) ₂ ] are subjected to an ion exchange reaction, thereby being represented by the above general formula (I). An ionic liquid can be generated.

  As the organic solvent used in the reaction of the cyclic phosphazene compound of the formula (II) and the tertiary amine of the formula (III), aromatic hydrocarbons, ester compounds and ether compounds are preferable. Here, toluene is preferable among aromatic hydrocarbons, ethyl acetate is preferable among ester compounds, and diethyl ether is preferable among ether compounds. These organic solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them.

The cyclic phosphazene compound represented by the general formula (II) is, for example, a commercially available cyclic phosphazene compound represented by (NPCl ₂ ) ₃ as a starting material, fluorinated all chlorine with a fluorinating agent, After introducing an alkoxy group, an amine group or the like into the target chlorine substitution site, chlorination with a chlorinating agent such as HCl or phosgene, or a commercially available phosphazene compound represented by (NPCl ₂ ) ₃ It is possible to synthesize by a method of adding a necessary amount of a fluorinating agent after calculating the equivalent amount of fluorine to be introduced.

  In the general formula (III), each R is independently an alkyl group, and examples of the alkyl group in R of the formula (III) include those exemplified in the section of the alkyl group in R of the formula (I). be able to.

  Specific examples of the tertiary amine represented by the general formula (III) include aliphatics such as trimethylamine, triethylamine, tripropylamine, tributylamine, trihexylamine, trioctylamine, butyldimethylamine, and hexyldimethylamine. A tertiary amine is mentioned.

In the reaction of the cyclic phosphazene compound of the formula (II) with the tertiary amine of the formula (III), the amount of the amine of the formula (III) used is 1 mol of chlorine in R ¹ in the cyclic phosphazene compound of the formula (II). A range of 1 to 1.5 mol is preferred. The concentration of the cyclic phosphazene compound of formula (II) in the organic solvent is preferably in the range of 1 to 5 mol / L, and the concentration of the amine of formula (III) in the organic solvent is 1 to 5 mol / L. A range of L is preferred. If the concentration of the cyclic phosphazene compound of formula (II) in the organic solvent is in the range of 1 to 5 mol / L, it is readily soluble in the organic solvent, and the concentration of the amine of formula (III) in the organic solvent is If it is the range of 1-5 mol / L, the produced | generated ionic compound (solid) will precipitate rapidly in a solvent, and reaction will not be inhibited.

  Further, the reaction temperature in the reaction of the cyclic phosphazene compound of the formula (II) and the amine of the formula (III) is not particularly limited, and the reaction proceeds sufficiently even at room temperature, but the range of 15 ° C to 50 ° C Can be controlled. If the reaction is fast, it is effective to lower the temperature in a timely manner. If the reaction is slow, the reaction rate can be increased by raising the temperature. However, when the temperature exceeds 50 ° C., the phosphazene compound that is a raw material is likely to volatilize, so that the reaction is preferably performed at 50 ° C. or less. Further, the reaction pressure is not particularly limited, and the reaction can be performed under atmospheric pressure. The reaction between the cyclic phosphazene compound of the formula (II) and the amine of the formula (III) is preferably carried out in an inert gas atmosphere such as nitrogen so that moisture does not enter the reaction system from the outside. By performing the reaction under an inert gas atmosphere, by-production of amine hydrochloride can be suppressed.

  The organic solvent used for the reaction between the ionic compound of formula (IV) and lithium bis (trifluoromethanesulfonyl) imide is preferably a halogenated hydrocarbon, and among the halogenated hydrocarbons, chloroform is preferred. In addition, the organic solvent to be used may be only 1 type, and 2 or more types of mixtures may be sufficient as it.

In the general formula (IV), one of the six R ² is an ionic substituent represented by the general formula (V), and the other five are fluorine.

  In the general formula (V), each R is independently an alkyl group, and examples of the alkyl group in R of the formula (V) include those exemplified in the section of the alkyl group in R of the formula (I). be able to.

  In the reaction of the ionic compound of formula (IV) with lithium bis (trifluoromethanesulfonyl) imide, the amount of lithium bis (trifluoromethanesulfonyl) imide used is 1 mol of chloride ion of the ionic compound of formula (IV). A range of 1 to 1.5 mol is preferred. The concentration of the ionic compound of formula (IV) in the organic solvent is preferably in the range of 1 to 5 mol / L, and the concentration of lithium bis (trifluoromethanesulfonyl) imide in the organic solvent is 1.5 to 7.5. A range of mol / L is preferred. If the concentration of the ionic compound of formula (IV) in the organic solvent is in the range of 1 to 5 mol / L, the solid substance insoluble in the organic solvent may occupy the volume in the solvent and inhibit the reaction. Few. On the other hand, the concentration of lithium bis (trifluoromethanesulfonyl) imide in the organic solvent should be about 1.5 times the concentration of the ionic compound of formula (IV), that is, in the range of 1.5 to 7.5 mol / L. For example, the ligand substitution reaction with chlorine ions can be carried out smoothly.

  The reaction temperature in the reaction between the ionic compound of formula (IV) and lithium bis (trifluoromethanesulfonyl) imide is not particularly limited, but is preferably in the range of room temperature to 50 ° C., and the reaction proceeds sufficiently even at room temperature. To do. Further, the reaction pressure is not particularly limited, and the reaction can be performed under atmospheric pressure.

  After producing the ionic liquid of formula (I) as described above, it is preferable to filter the resulting reaction mixture to remove LiCl produced as a by-product. Here, the filtration method is not particularly limited, and it may be filtered under a normal pressure or a reduced pressure using a known filter medium.

  Moreover, after removing LiCl by filtration, the filtrate is centrifuged to collect a supernatant, and activated carbon is preferably added to the obtained supernatant to remove reaction by-products. Here, the centrifugation method is not particularly limited, and can be carried out by a usual method using a known centrifuge. In addition, the rotational speed in centrifugation is not specifically limited, However, The range of 9000-12000 rpm is preferable. Moreover, the activated carbon to be used is not particularly limited, and known activated carbon can be used. The amount of the activated carbon used is not particularly limited, but is preferably in the range of 1 to 5 g per 1 g of the ionic liquid of the formula (I).

  After the treatment with activated carbon, for example, the activated carbon is removed by filtration, and the ionic liquid of formula (I) can be isolated by distilling off the organic solvent used.

  The ionic liquid of the present invention described above has at least a melting point of 50 ° C. or less, preferably a melting point of 25 ° C. or less, and is used for an electric double layer capacitor electrolyte, a lithium ion battery electrolyte, and a dye-sensitized solar cell. It can be used as an electrolytic solution, a reaction solvent for organic synthesis, an extraction solvent for organic compounds, a magnetic fluid, and the like. In addition, the ionic liquid of the present invention surprisingly has a high light emitting property and emits light even at a high temperature. For example, a light emitting material under a high temperature condition, a polymer or a resin material that requires a high temperature process, and the like. It is also useful as an agent for imparting light-emitting properties.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

で表わされる化合物［即ち、上記一般式(IV)で表され、６つのＲ²のうち５つがフッ素で且つ１つが−Ｎ⁺(Ｃ₄Ｈ₉)₃Ｃｌ^-である化合物］であることを確認した。 (Comparative Example 1)
In a three-necked flask equipped with a reflux condenser, 1.5 mL (0.01 mol) of a cyclic phosphazene compound represented by the above chemical formula (II) and tri-n-butylamine [that is, represented by the above general formula (III), 3 Tertiary amine in which all R are n-butyl groups] 1.72 mL (0.01 mol) is dissolved in 30 mL of dehydrated dimethyl ether, stirred at 20 ° C. for 3 hours, and then dimethyl ether is distilled off with an evaporator. As a result, 1.72 g of liquid (yield 21%) was obtained. When the obtained liquid was dissolved in deuterated chloroform and analyzed by ¹ H-NMR and ¹³ C-NMR, the liquid was represented by the following chemical formula (a):

A compound represented by the above general formula (IV), in which 5 out of 6 R ² are fluorine and 1 is —N ⁺ (C ₄ H ₉ ) ₃ Cl ^−. confirmed.

で表わされる化合物［即ち、上記一般式(I)で表され、３つのＲの総てがｎ-ブチル基である化合物］であることを確認した。 Example 1
After dissolving the ionic liquid obtained in Comparative Example 1 in 30 mL of chloroform, 0.49 g of bis (trifluoromethanesulfonyl) imidolithium [LiN (SO ₂ CF ₃ ) ₂ ] was added and stirred at room temperature for 1 hour. However, LiCl precipitated. The precipitated LiCl was separated by filtration, and the filtrate was further centrifuged at 12000 rpm for 30 minutes using a centrifuge, and the supernatant was collected. Next, the obtained supernatant was dissolved in 30 mL of chloroform, and 5 g of activated carbon was further added to remove the coloring components. Next, the activated carbon was removed by filtration, chloroform was removed by an evaporator, and further, drying was performed at 150 ° C. for 24 hours under reduced pressure using a vacuum pump to obtain 1.13 g of liquid (yield 16%). When the obtained liquid was dissolved in deuterated chloroform and analyzed by ¹ H-NMR and ¹³ C-NMR, the liquid was represented by the following chemical formula (b):

[That is, a compound represented by the above general formula (I), in which all three R's are n-butyl groups].

[Spectral data (250 MHz, CDCl ₃ , δ / ppm)]
^{· 1 H-NMR: δ =} 0.98 (t, J = 7.25 Hz, 3H) ·· H A, δ = 1.38 (m, 2H) ·· H B, δ = 1.75 (m, 2H) ·· H C, δ = 2.97 (m, J = 5.04 Hz, 6H) ・ ・ H _D
¹³ C-NMR: δ = 13.1 (s), C _E , δ = 19.6 (s), C _F , δ = 25.3 (s), C _G , δ = 53.0 (s), C _H , δ = 119.5 (q, J = 1275 Hz) ・ ・ C _I

で表わされる化合物［即ち、上記一般式(I)で表され、３つのＲの総てがｎ-オクチル基である化合物］であることを確認した。 (Example 2)
In a three-necked flask equipped with a reflux condenser, 1.5 mL (0.01 mol) of the cyclic phosphazene compound represented by the above chemical formula (II) and tri-n-octylamine [that is, represented by the above general formula (III), Tertiary amine in which all three Rs are n-octyl groups] 4.38 mL (0.01 mol) was dissolved in 30 mL of dehydrated dimethyl ether, stirred at 20 ° C for 3 hours, and then dimethyl ether was distilled off with an evaporator. Thus, an ionic compound represented by the above general formula (IV), in which 5 out of 6 R ² were fluorine and 1 was —N ⁺ (C ₈ H ₁₇ ) ₃ Cl ⁻ was obtained. After dissolving the ionic compound in 30 mL of chloroform, 0.37 g of bis (trifluoromethanesulfonyl) imidolithium [LiN (SO ₂ CF ₃ ) ₂ ] was added and stirred at room temperature for 1 hour. did. The precipitated LiCl was separated by filtration, and the filtrate was further centrifuged at 12000 rpm for 30 minutes using a centrifuge, and the supernatant was collected. Next, the obtained supernatant was dissolved in 30 mL of chloroform, and 5 g of activated carbon was further added to remove the coloring components. Next, the activated carbon was removed by filtration, chloroform was removed with an evaporator, and further, drying was performed at 150 ° C. for 24 hours under reduced pressure with a vacuum pump to obtain 0.93 g of liquid (yield 10%). When the obtained liquid was dissolved in deuterated chloroform and analyzed by ¹ H-NMR and ¹³ C-NMR, the liquid was represented by the following chemical formula (c):

[That is, a compound represented by the above general formula (I), in which all three R's are n-octyl groups].

[Spectral data (400 MHz, CDCl ₃ , δ / ppm)]
・¹ H-NMR: δ = 0.89 (t, J = 6.72 Hz, 3H) ・ H _A , δ = 1.29 (m, 10H) ・ H _B , δ = 1.67 (m, 2H) ・ H _C , δ = 3.02 (m, 2H) ·· H D
¹³ C-NMR: δ = 14.0 (s), C _F , δ = 22.5 (s), C _G , δ = 23.3 (s), C _H , δ = 26.5 (s), C _I , δ = 28.9 (s) ·· C _J , δ = 31.6 (s) · · C _K , δ = 53.0 (s) · · C _L , δ = 119.5 (q, J = 1275 Hz) · · C _M

で表わされる化合物［即ち、上記一般式(I)で表され、３つのＲのうち２つがメチル基で且つ１つがｎ-ブチル基である化合物］であることを確認した。 (Example 3)
In a three-necked flask equipped with a reflux condenser, 1.5 mL (0.01 mol) of the cyclic phosphazene compound represented by the above chemical formula (II) and n-butyldimethylamine [that is, represented by the above general formula (III), 3 Tertiary amine, one of which is an n-butyl group and two methyl groups] 1.40 mL (0.01 mol) is dissolved in 30 mL of dehydrated dimethyl ether and stirred at 20 ° C. for 3 hours. Dimethyl ether was distilled off, and the ionicity represented by the above general formula (IV), in which 5 out of 6 R ² were fluorine and 1 was —N ⁺ (C ₄ H ₉ ) (CH ₃ ) ₂ Cl ⁻ A compound was obtained. After dissolving the ionic compound in 30 mL of chloroform, 0.32 g of bis (trifluoromethanesulfonyl) imidolithium [LiN (SO ₂ CF ₃ ) ₂ ] was added and stirred at room temperature for 1 hour. did. The precipitated LiCl was separated by filtration, and the filtrate was further centrifuged at 12000 rpm for 30 minutes using a centrifuge, and the supernatant was collected. Next, the obtained supernatant was dissolved in 30 mL of chloroform, and 5 g of activated carbon was further added to remove the coloring components. Next, the activated carbon was removed by filtration, chloroform was removed by an evaporator, and further, drying was performed at 150 ° C. for 24 hours under reduced pressure using a vacuum pump to obtain 0.52 g of a liquid (yield 8.4%). When the obtained liquid was dissolved in deuterated chloroform and analyzed by ¹ H-NMR and ¹³ C-NMR, the liquid was represented by the following chemical formula (d):

[That is, a compound represented by the above general formula (I), wherein two of the three Rs are methyl groups and one is an n-butyl group].

[Spectral data (400 MHz, CDCl ₃ , δ / ppm)]
^-1 H-NMR: δ = 0.97 (t, J = 7.36 Hz, 3H) · · H _A , δ = 1.41 (m, 2H) · · H _B , δ = 1.71 (m, 2H) · · H _C , δ = 2.89 (d, J = 5.04 Hz, 6H) ·· H _D , δ = 3.07 (m, 2H) ·· H _E
^{· 13 C-NMR: δ =} 13.3 (s) ·· C F, δ = 19.5 (s) ·· C G, δ = 26.3 (s) ·· C H, δ = 43.7 (s) ·· C I, δ = 58.8 (s) ·· C _J , δ = 119.5 (q, J = 1275 Hz) ·· C _K

で表わされる化合物［即ち、上記一般式(I)で表され、３つのＲのうち２つがメチル基で且つ１つがｎ-ヘキシル基である化合物］であることを確認した。 Example 4
In a three-necked flask equipped with a reflux condenser, 1.5 mL (0.01 mol) of a cyclic phosphazene compound represented by the above chemical formula (II) and n-hexyldimethylamine [that is, represented by the above general formula (III), 3 Tertiary amine in which one of the Rs is an n-hexyl group and two are methyl groups] 2.08 mL (0.01 mol) is dissolved in 30 mL of dehydrated dimethyl ether and stirred at 20 ° C. for 3 hours. Dimethyl ether was distilled off, and the ionicity represented by the above general formula (IV), in which 5 out of 6 R ² were fluorine and 1 was —N ⁺ (C ₆ H ₁₃ ) (CH ₃ ) ₂ Cl ⁻ A compound was obtained. After dissolving the ionic compound in 30 mL of chloroform, 0.22 g of bis (trifluoromethanesulfonyl) imidolithium [LiN (SO ₂ CF ₃ ) ₂ ] was added and stirred at room temperature for 1 hour. did. The precipitated LiCl was separated by filtration, and the filtrate was further centrifuged at 12000 rpm for 30 minutes using a centrifuge, and the supernatant was collected. Next, the obtained supernatant was dissolved in 30 mL of chloroform, and 5 g of activated carbon was further added to remove the coloring components. Next, the activated carbon was removed by filtration, chloroform was removed by an evaporator, and further, drying was performed at 150 ° C. for 24 hours under reduced pressure using a vacuum pump to obtain 0.58 g of liquid (yield 8.9%). When the obtained liquid was dissolved in deuterated chloroform and analyzed by ¹ H-NMR and ¹³ C-NMR, the liquid was represented by the following chemical formula (e):

[That is, a compound represented by the above general formula (I), wherein two of the three Rs are methyl groups and one is an n-hexyl group].

[Spectral data (400 MHz, CDCl ₃ , δ / ppm)]
・¹ H-NMR: δ = 0.89 (t, J = 6.76 Hz, 3H) ・ H _A , δ = 1.32 (m, 6H) ・ H _B , δ = 1.67 (m, 2H) ・ H _C , δ = 2.85 (s, 6H) ·· H _D , δ = 2.93 (m, 2H) ·· H _E
^{· 13 C-NMR: δ =} 13.8 (s) ·· C F, δ = 19.5 (s) ·· C G, δ = 22.3 (s) ·· C H, δ = 24.7 (s) ·· C I, δ = 31.1 (s) ·· C _J , δ = 43.5 (s) · · C _K , δ = 58.7 (s) · · C _L , δ = 119.5 (q, J = 1275 Hz) · · C _M

<Measurement of luminescence quantum yield>
The luminescence quantum yields of the ionic liquids obtained in the above Examples and Comparative Examples were measured as relative values of the fluorescence quantum yield of 4-aminophthalimide. The excitation wavelength was 360 nm, each ionic liquid was dissolved in methanol at a concentration of 0.1 mol / L, and measurement was performed at room temperature (25 ° C.), 100 ° C., and 150 ° C. The results are shown in Table 1. For comparison, the luminescence quantum yield of 1-methyl-3-butylimidazolium hexafluorophosphate ([bmim] PF ₆ ) is also shown.

  From Table 1, it can be seen that the ionic liquids of the examples have higher emission quantum yields than the ionic liquids of the comparative examples, and in particular, the emission quantum yields at high temperatures are higher.

Claims (2)

The following general formula (I):

A luminescent ionic liquid represented by the formula: wherein each R is independently an alkyl group.   The luminescent ionic liquid according to claim 1, wherein R is an alkyl group having 1 to 8 carbon atoms.