JP2015174976A - Fluorescent material and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent material excellent in supply performance and fluorescence quantum efficiency.SOLUTION: There is provided a fluorescent material containing a citric acid analog represented by the general formula (1) defined by HOC(CHCOX)(CHCOX)COX, where X, Xand Xeach independently represent a hydroxy group, an amino group or a monoalkylamino group. Also provided is a method of producing the fluorescent material, comprising the step of heating the citric acid analog.

Description

  The present invention relates to a phosphor and a method for producing the same, and more particularly to a phosphor that can be used for a probe, a light emitting element, an LED, a display, a fluorescent tag, and the like for detecting a biochemical reaction.

A phosphor refers to a substance that exhibits fluorescence when electrons excited by absorbing light of a specific wavelength return to the ground state.
For example, a phosphor in which a matrix made of metal oxide, metal nitride, metal sulfide or the like is doped with a metal such as europium or cerium that is the emission center is known, but the rareness of the metal that becomes the emission center is known Therefore, there is a problem in the supply property of the phosphor.

  As a phosphor containing no metal, for example, a carbon phosphor made of a nitrogen-containing graphene nanosheet is known (see Patent Document 1). Such a nitrogen-containing graphene nanosheet can be obtained by dispersing graphite oxide and / or graphene oxide in an aqueous solution in which a nitrogen-containing compound such as urea is dissolved and heating at 60 ° C. or higher. However, such a carbon phosphor has a problem of low fluorescence quantum efficiency.

JP 2012-136666 A

  An object of the present invention is to provide a phosphor excellent in supply ability and fluorescence quantum efficiency.

In order to achieve the above object, the present invention
[1] A phosphor containing a citric acid analog represented by the following general formula (1) (hereinafter referred to as “citric acid analog (1)”);
HOC (CH ₂ COX ¹ ) (CH ₂ COX ² ) COX ³ (1)
(In the formula, X ¹ , X ² and X ³ each independently represent a hydroxyl group, an amino group or a monoalkylamino group.)
[2] The phosphor according to the above [1], which exhibits a fluorescence wavelength of 400 to 500 nm;
[3] The phosphor of the above [1] or [2] obtained by heating the citric acid analog (1);
[4] The method for producing a phosphor according to any one of the above [1] to [3], comprising a step of heating the citric acid analog (1);
[5] The method for producing a phosphor according to the above [4], wherein X ¹ , X ² and X ^{3 in the} general formula (1) are all hydroxyl groups and the heating temperature is in the range of 120 to 170 ° C .; And [6] At least any ^one of X ¹ , X ² and X ^{3 in} the general formula (1) is an amino group or a monoalkylamino group, and the heating temperature is in the range of 120 to 150 ° C. The method for producing the phosphor according to [5] above;
I will provide a.

  The phosphor of the present invention does not contain a metal that leads to a decrease in supply performance, and exhibits high fluorescence quantum efficiency. Such a phosphor can be easily produced by the production method of the present invention.

2 is a fluorescence spectrum of the phosphor of the present invention obtained in Example 1. 2 is a ¹ H-NMR chart of the phosphor of the present invention obtained in Example 1. FIG. 3 is a fluorescence spectrum of the phosphor of the present invention obtained in Example 2. 4 is a fluorescence spectrum of the phosphor of the present invention obtained in Example 3. 4 is a fluorescence spectrum of the phosphor of the present invention obtained in Example 4.

<Phosphor>
The phosphor of the present invention contains a citric acid analog (1) and is excited by light irradiation to exhibit fluorescence. The fluorescent quantum efficiency of such a phosphor is preferably 25% or more. In such a phosphor, it is thought that the molecules of the citric acid analog (1) exhibit fluorescence by taking a specific association state.

The primary structure of the citric acid analog (1) is represented by the following general formula (1).
HOC (CH ₂ COX ¹ ) (CH ₂ COX ² ) COX ³ (1)
(In the formula, X ¹ , X ² and X ³ each independently represent a hydroxyl group, an amino group or a monoalkylamino group.)

The monoalkylamino group represented by X ¹ , X ² and X ^{3 in the} general formula (1) means a structure in which one hydrogen atom of the amino group is substituted with an alkyl group. Such an alkyl group may have a substituent such as a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, etc.) or a hydroxyl group.
Specific examples of the monoalkylamino group include N-methylamino group, N-ethylamino group, Nn-propylamino group, N-isopropylamino group, Nn-butylamino group, N-isobutylamino group, N-hydroxymethylamino group, N-hydroxyethylamino group, N-hydroxypropylamino group, N-chloromethylamino group, N-chloroethylamino group, N-chloropropylamino group, N-bromomethylamino group, N -Bromoethylamino group, N-bromopropylamino group, etc. are mentioned.

  Specific examples of the citric acid analog (1) include citric acid, citric acid monoamide, citric acid diamide, citric acid triamide, N-methylcitric acid monoamide, N, N′-dimethylcitric acid diamide, N, N ′, N ″ -trimethyl citrate triamide, N-ethyl citrate monoamide, N, N′-diethyl citrate diamide, N, N ′, N ″ -triethyl citrate triamide, N-propyl citrate monoamide, N, N '-Dipropylcitric acid diamide, N, N', N ″ -tripropylcitric acid triamide, N-isopropylcitric acid monoamide, N, N′-diisopropylcitric acid diamide, N, N ′, N ″ -tri Isopropyl citrate triamide, N-butyl citrate monoamide, N, N′-dibutyl citrate diamide, N, N ′, N ′ -Tributyl citrate triamide, N-hydroxymethyl citrate monoamide, N, N'-dihydroxymethyl citrate diamide, N, N ', N' '-trihydroxymethyl citrate triamide, N-hydroxyethyl citrate monoamide, N , N′-dihydroxyethyl citrate diamide, N, N ′, N ″ -trihydroxyethyl citrate triamide, N-chloromethyl citrate monoamide, N, N′-dichloromethyl citrate diamide, N, N ′, N ″ -trichloromethyl citrate triamide, N-chloroethyl citrate monoamide, N, N′-dichloroethyl citrate diamide, N, N ′, N ″ -trichloroethyl citrate triamide, N-bromomethyl citrate Monoamide, N, N′-dibromomethylcitric acid diamide, N N ′, N ″ -tribromomethyl citrate triamide, N-bromoethyl citrate monoamide, N, N′-dibromoethyl citrate diamide, N, N ′, N ″ -tribromoethyl citrate triamide, etc. Can be mentioned.

  The phosphor of the present invention preferably exhibits a fluorescence wavelength of 400 to 500 nm. In the present specification, the fluorescence wavelength means the peak top wavelength of the maximum peak of the fluorescence spectrum. That is, the peak top wavelength of the maximum peak of the fluorescence spectrum in the phosphor of the present invention is preferably in the range of 400 to 500 nm.

  The phosphor of the present invention may contain only one type of citric acid analog (1) or a plurality of types.

  Such phosphors may contain other phosphors, binders and the like as long as the object of the present invention is not impaired.

<Method for producing phosphor>
As citric acid analog (1) which is a raw material of the phosphor of the present invention, citric acid amide (wherein at least one of X ¹ , X ² and X ^{3 in} the general formula (1) is an amino group ( In the case of using “citric acid amide (A)” hereinafter, the citric acid amide (A) can be produced by reacting citric acid and urea, preferably in water. In this case, the amount of urea used is usually in the range of 1 to 4 moles of citric acid.
If the amount of urea used is less than 3 moles of citric acid, the product is usually ^one in which X ¹ , X ² and X ³ are amino groups (monoamide), two are amino groups Some (diamide), three are amino groups (triamide), and a mixture of unreacted citric acid. On the other hand, if the amount of urea used is 3 mol times or more of citric acid, triamide can be selectively obtained.
In the reaction of citric acid and urea, water is preferably present at 0.1 to 20 times by mass of citric acid, more preferably 2 to 10 times by mass. Moreover, the water which does not contain metal ions, such as purified water, ion-exchange water, and distilled water, is preferable.
The gas phase atmosphere in the reaction of citric acid and urea is preferably an inert gas atmosphere such as nitrogen or argon. The reaction temperature is preferably 10 to 80 ° C, more preferably 20 to 60 ° C.

As the citric acid analog (1) used as the raw material of the phosphor of the present invention, citric acid amide (hereinafter referred to as at least one of X ¹ , X ² and X ^{3 in} the general formula (1) is a monoalkylamino group) When "citric acid amide (B)" is used, the citric acid amide (B) can be produced by reacting citric acid with a monoalkylamine in water. In this case, the amount of monoalkylamine used is usually in the range of 1 to 4 moles of citric acid.
When the amount of monoalkylamine used is less than 3 moles of citric acid, the product is usually ^{one in which one} of X ¹ , X ² and X ³ is a monoalkylamino group (monoamide), 2 One is a monoalkylamino group (diamide), the other is a monoalkylamino group (triamide) and a mixture of unreacted citric acid, and the amount of monoalkylamine used is 3 moles or more of citric acid. Triamide is selectively obtained.
In the reaction of citric acid and monoalkylamine, water is preferably present at 0.1 to 20 times by mass of citric acid, more preferably 2 to 10 times by mass. Moreover, the water which does not contain metal ions, such as purified water, ion-exchange water, and distilled water, is preferable.
The reaction is preferably performed in an inert gas atmosphere such as nitrogen or argon. The reaction temperature is preferably 10 to 80 ° C, more preferably 20 to 60 ° C.

  The citric acid amide (A) and citric acid amide (B) obtained by the above-described method should be used for the production of phosphors by heating while removing water, as will be described later, without isolation after production. Can do.

  The phosphor of the present invention can be obtained by heating the citric acid analog (1). Heating is preferably performed in an inert gas atmosphere such as nitrogen or argon. The heating temperature can be selected according to the thermal stability of the citric acid analog and is usually in the range of 120 to 170 ° C. The heating time is usually 10 to 500 minutes, preferably 20 to 300 minutes.

When X ¹ , X ² and X ^{3 in the} general formula (1) are all hydroxyl groups, that is, when citric acid is used as the citric acid analog (1), the heating temperature is in the range of 120 to 170 ° C. Preferably, the range of 130-165 degreeC is more preferable.

When the citric acid analog (1) in which at least one of X ¹ , X ² and X ^{3 in} the general formula (1) is an amino group or a monoalkylamino group is used, the heating temperature is 120 to 150. The range of ° C is preferred, and the range of 130 to 145 ° C is more preferred.

  The citric acid analog (1) may be heated in the absence of a solvent or in the presence of a solvent. The amount of the solvent used is preferably 20 times by mass or less of the citric acid analog (1), and more preferably 2 to 10 times by mass from the viewpoint of solubility of the citric acid analog (1).

  When heating the citric acid analog (1) in the presence of water, it is preferable to perform heating while removing water from the viewpoint of suppressing hydrolysis of the citric acid analog (1) accompanying heating.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited by this Example.

[Evaluation of phosphor]
The phosphors obtained in the examples and the compounds obtained in the comparative examples were evaluated as follows.
1. Elemental analysis Using a fully automatic elemental analyzer (manufactured by Perkin Elmer, 2400II), the carbon (C), hydrogen (H), and nitrogen (N) content rates are measured, Compared.
2. Mass spectrometry Measurement was performed by the EI method using a mass spectrometer (JEOL Ltd., JMS-MS700v type).
3. ¹ H-NMR
Nuclear magnetic resonance apparatus: manufactured by JEOL Ltd. Product name: LAMBDA (NMR500)
Solvent: heavy water4. Wavelength distribution and fluorescence quantum yield Using a spectrofluorometer (manufactured by JASCO Corporation, FP-8000) powder measurement cartridge, irradiates light with a wavelength of 360 nm, and observes the wavelength distribution of excited and emitted fluorescence. The fluorescence quantum yield was determined from the photons produced / incident photons.

[Example 1]
In a 10 ml three-necked flask, citric acid monohydrate 2.10 g (0.01 mol) (manufactured by Wako Pure Chemical Industries, Ltd.), urea 1.8 g (0.03 mol) (manufactured by Wako Pure Chemical Industries, Ltd.) And 3 ml of ion-exchanged water was added to prepare a solution at 25 ° C.
A three-necked flask prepared with such a solution was equipped with a thermometer and a reflux tube, heated at an internal temperature of 60 ° C. for 180 minutes, and then irradiated with ultraviolet rays, but the contents did not exhibit fluorescence. Subsequently, the reflux tube was replaced with a reflux head, and the water to be evaporated was condensed and distilled while the internal temperature was raised to 140 ° C. Distillation of water started from an internal temperature of 110 ° C., and about 3 g of water was distilled off in 30 minutes. After the internal temperature reached 140 ° C., heating was performed for 120 minutes. When the three-necked flask was irradiated with ultraviolet rays, the contents showed fluorescence. After cooling to room temperature, it was connected to a vacuum pump and dried under reduced pressure at 133 Pa (1 Torr) and 80 ° C. for 3 hours to obtain 1.84 g of a phosphor. From the results of elemental analysis and ¹ H-NMR measurement, the obtained phosphor was found to contain citric acid triamide at a high concentration. The yield is calculated to be 97% assuming that the total amount is citric acid triamide. Table 1 shows the calculated values of the elemental composition of citric acid triamide, the elemental analysis results of the obtained phosphor, and the fluorescence quantum yield. The fluorescence spectrum of the phosphor is shown in FIG. 1, and the ¹ H-NMR spectrum is shown in FIG. From the results of elemental analysis and ¹ H-NMR measurement, the obtained solid is considered to be high-purity citric acid triamide.

[Example 2]
It implemented like Example 1 except having used ethanolamine 1.83g (0.03mol) (made by Wako Pure Chemical Industries Ltd.) instead of urea, and obtained 3.09g phosphor. The phosphor obtained from the results of elemental analysis and ¹ H-NMR measurement was found to contain N, N ′, N ″ -trihydroxyethyl citrate triamide at a high concentration. Assuming the total amount is N, N ′, N ″ -trihydroxyethyl citrate triamide, the yield is calculated as 96%. The calculated values of the elemental composition of N, N ′, N ″ -trihydroxyethyl citrate triamide, the results of elemental analysis of the obtained phosphor and the fluorescence quantum yield are shown in Table 1, and the fluorescence spectrum of the phosphor is shown in FIG. Shown in

[Example 3]
The same procedure as in Example 1 was conducted, except that 1.77 g (0.03 mol) of propylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of urea to obtain 3.04 g of a phosphor. From the results of elemental analysis and ¹ H-NMR measurement, the obtained phosphor was found to contain N, N ′, N ″ -tripropylcitric acid triamide at a high concentration. Assuming the total amount is N, N ′, N ″ -tripropylcitric acid triamide, the yield is calculated as 96%. The calculated values of the elemental composition of N, N ′, N ″ -tripropylcitric acid triamide, the elemental analysis results and the fluorescence quantum yield of the obtained phosphor are shown in Table 1, and the fluorescence spectrum of the phosphor is shown in FIG. Show.

[Example 4]
2.10 g (0.01 mol) of citric acid monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) was added to a 10 ml three-necked flask equipped with a thermometer and a reflux tube, and the internal temperature was 60 ° C. After heating for 120 minutes, the temperature was raised to 160 ° C. and heated for 30 minutes. After cooling to room temperature, it was connected to a vacuum pump and dried at 133 Pa (1 Torr) and 80 ° C. for 3 hours to obtain 1.90 g of a phosphor. From the results of elemental analysis, ¹ H-NMR and melting point (measured according to JIS-K0064), it was found that the obtained phosphor contained citric acid at a high concentration. Assuming the total amount is citric acid, the yield is calculated as 99%. The calculated values of the elemental composition of citric acid, the results of elemental analysis of the obtained phosphor and the fluorescence quantum yield are shown in Table 1, and the fluorescence spectrum of the phosphor is shown in FIG.

[Example 5]
In Example 2, it carried out like Example 2 except the usage-amount of ethanolamine having been 1.22 g (0.02 mol). 2.74 g of phosphor was obtained. ^From the measurement result of ¹ H-NMR, the obtained phosphor was obtained from N, N ′, N ″ -trihydroxyethyl citrate triamide, N, N′-dihydroxyethyl citrate diamide, N, -monohydroxyethyl citrate. It was found to contain acid monoamide and citric acid, respectively.

[Comparative Example 1]
The same operation as in Example 1 was carried out except that 2.8 g (0.03 mol) of aniline was used instead of urea. Although the obtained solid absorbed ultraviolet rays, no fluorescence was observed in the visible light region.

[Comparative Example 2]
A solid was obtained in the same manner as in Example 4 except that the heating temperature and the drying temperature were 40 ° C. ^From the measurement results of ¹ H-NMR and melting point (measured according to JIS-K0064), it was found that the obtained solid was a high-purity citric acid / hydrate. Assuming that the total amount is citric acid monohydrate, the yield is calculated as 99%. Such citric acid monohydrate did not observe fluorescence.

  The phosphor of the present invention can be used for probes for detecting biochemical reactions, light emitting elements, LEDs, displays, fluorescent tags, and the like.

Claims (6)

A phosphor containing a citric acid analog represented by the following general formula (1).
HOC (CH ₂ COX ¹ ) (CH ₂ COX ² ) COX ³ (1)
(In the formula, X ¹ , X ² and X ³ each independently represent a hydroxyl group, an amino group or a monoalkylamino group.) The phosphor according to claim 1, which exhibits a fluorescence wavelength of 400 to 500 nm. The phosphor according to claim 1 or 2, wherein a citric acid analog represented by the following general formula (1) is heated.
HOC (CH ₂ COX ¹ ) (CH ₂ COX ² ) COX ³ (1)
(In the formula, X ¹ , X ² and X ³ each independently represent a hydroxyl group, an amino group or a monoalkylamino group.) The manufacturing method of the fluorescent substance in any one of Claims 1-3 including the process of heating the citric acid analog shown by following General formula (1).
HOC (CH ₂ COX ¹ ) (CH ₂ COX ² ) COX ³ (1)
(In the formula, X ¹ , X ² and X ³ each independently represent a hydroxyl group, an amino group or a monoalkylamino group.) The method for producing a phosphor according to claim 4, wherein X ¹ , X ² and X ^{3 in the} general formula (1) are all hydroxyl groups and the heating temperature is in the range of 120 to 170 ° C. 5. At least one of X ¹ , X ² and X ^{3 in} the general formula (1) is an amino group or a monoalkylamino group, and the heating temperature is in the range of 120 to 150 ° C. 5. A method for producing the phosphor according to 1.

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