JP7274134B2 - Rare earth compounds, light emitters, light emitting devices, wavelength conversion materials and security materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rare earth compound, and a light emitter, light emitting device, wavelength conversion material and security material using the same.

Fluorescent materials that efficiently and strongly emit light are expected to be applied to various uses such as light-emitting devices, wavelength conversion materials, and security materials. As fluorescent materials, in addition to inorganic phosphors (for example, Patent Document 1), rare earth compounds utilizing strong light absorption by organic ligands have also been proposed (for example, Patent Documents 2 and 3).

JP 2015-196717 A WO2012/150712 WO2016/143561

A luminous body tends to decrease in emission intensity at high temperatures. The temperature of various devices using light emitters may reach, for example, about 150° C. in the case of a light-emitting diode element. A decrease in light emission intensity at such a high temperature causes a decrease in efficiency, a shift in chromatic aberration, a decrease in device life, and the like. can cause various problems of In particular, conventional rare earth compounds having organic ligands are excellent in terms of high efficiency and strong light emission, but tend to be insufficient in light emission intensity at high temperatures.

Accordingly, an object of one aspect of the present invention is to suppress a decrease in emission intensity at high temperatures with respect to a rare earth compound having an organic ligand.

で表される２個のホスフィンオキシド配位子と、を含み、２個の前記希土類イオンが、それらの両方に配位した２個の前記ホスフィンオキシド配位子によって連結されている、希土類化合物を提供する。式（Ｉ）において、Ｃ^１、Ｃ^２及びＣ^３は炭素原子を示し、ＡｒはＣ^１、Ｃ^２及びＣ^３を含みＸ^１以外の置換基を有していてもよい、２価の単環芳香族基又は縮合多環芳香族基を示し、Ｘ^１はハロゲン原子、置換基を有していてもよい炭素数１～２０の炭化水素基、置換基を有していてもよいアルコキシ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよいアルカノイルオキシ基、置換基を有していてもよいアリールオキシ基、置換基を有していてもよいアリールオキシカルボニル基、置換基を有していてもよいアリールカルボニルオキシ基、水酸基、カルボキシル基又はシアノ基を示し、Ｒ^１は置換基を有していてもよい芳香族基、又は直鎖若しくは環状脂肪族基を示す。同一分子内の複数のＡｒ、Ｘ^１及びＲ^１は、それぞれ同一でも異なっていてもよい。One aspect of the invention is two trivalent rare earth ions,
Formula (I) below:

two phosphine oxide ligands represented by offer. In formula (I), C ¹ , C ² and C ³ represent carbon atoms, Ar is a divalent unit containing C ¹ , C ² and C ³ and optionally having a substituent other than X ¹ represents a ring aromatic group or condensed polycyclic aromatic group, X ¹ is a halogen atom, an optionally substituted hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted alkoxy group , optionally substituted alkoxycarbonyl group, optionally substituted alkanoyloxy group, optionally substituted aryloxy group, optionally substituted aryl an oxycarbonyl group, an optionally substituted arylcarbonyloxy group, a hydroxyl group, a carboxyl group or a cyano group, wherein R ¹ is an optionally substituted aromatic group, or a linear or cyclic aliphatic group; indicates a family group. Plural Ar, X ¹ and R ¹ in the same molecule may be the same or different.

In formula (I), the bond between ^C2 and ^C1 is expressed as a single bond for the sake of convenience, but ^C2 is not limited to a single bond as long as it is directly bonded to ^C1 via a covalent bond. The bond between ^C2 and ^C1 is usually a covalent bond that constitutes the conjugated system of the aromatic group Ar.

Since the substituents X ¹ are respectively bonded to C ² adjacent to C ¹ , Ar, which is a planar aromatic group, tends to be in a mutually twisted arrangement. According to the findings of the present inventors, two phosphine oxide ligands form a binuclear body having a stable stack structure by adopting a staggered arrangement of planar aromatic groups Ar. It is believed that this contributes to the suppression of the decrease in emission intensity at high temperatures.

Another aspect of the invention provides light emitters and security materials comprising the rare earth compounds described above. A light emitter can be used, for example, as a light source for a light emitting device.

According to one aspect of the present invention, it is possible to suppress a decrease in emission intensity at high temperatures with respect to a rare earth compound having an organic ligand. Since the rare earth compound according to one aspect of the present invention exhibits a narrow emission spectrum with a half-value, it is also excellent in terms of the stability of the emission spectrum.

4 is a graph showing the results of thermogravimetric and differential thermal analysis of Eu ₂ (hfa) ₆ (Fdpbp) _2. FIG. Emission excitation spectrum of Eu ₂ (hfa) ₆ (Fdpbp) ₂ at 25°C. Emission spectra of _Eu2 (hfa) ₆ (Fdpbp) ₂ at 25°C and 200°C. 4 is a graph showing the relationship between the emission intensity of rare earth compounds and temperature. Fig. 3 shows emission excitation spectra of _Eu2 (hfa) ₆ (Fdpbp) ₂ , _Tb2 (hfa) ₆ (Fdpbp) ₂ and _Yb2 (hfa) ₆ (Fdpbp) ₂ at 25°C.

Several embodiments of the invention are described in detail below. However, the present invention is not limited to the following embodiments.

で表される２個のホスフィンオキシド配位子を含む。２個の希土類イオンが、それらの両方に配位した２個のホスフィンオキシド配位子によって連結されている。An aromatic compound according to one embodiment comprises two trivalent rare earth ions,
Formula (I) below:

contains two phosphine oxide ligands represented by Two rare earth ions are linked by two phosphine oxide ligands coordinated to both of them.

In formula (I), C ¹ , C ² and C ³ represent carbon atoms. Ar represents a divalent monocyclic aromatic group or condensed polycyclic aromatic group containing C ¹ , C ² and C ³ and optionally having a substituent other than X ¹ . X ¹ is a halogen atom, an optionally substituted hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted alkoxy group, an optionally substituted alkoxycarbonyl group, optionally substituted alkanoyloxy group, optionally substituted aryloxy group, optionally substituted aryloxycarbonyl group, optionally substituted aryl represents a carbonyloxy group, hydroxyl group, carboxyl group or cyano group; R ¹ represents an optionally substituted aromatic group or a linear or cyclic aliphatic group. Plural Ar, X ¹ and R ¹ in the same molecule may be the same or different.

A halogen atom as X ¹ may be a fluorine atom, a bromine atom or a chlorine atom. The hydrocarbon group as X ¹ may be a linear, branched or cyclic alkyl group, examples of which include a methyl group and an ethyl group. The alkoxy group, alkoxycarbonyl group and alkanoyloxy group as X ¹ may have 1 to 20 carbon atoms. The aryl group of the aryloxy group, aryloxycarbonyl group, or arylcarbonyloxy group as X ¹ may be a phenyl group.

Two Ars in the same molecule may be the same or different, but are typically the same. A monocyclic aromatic group as Ar can be an aromatic hydrocarbon group or an aromatic heterocyclic group. Examples of monocyclic aromatic groups include residues derived by removing two hydrogen atoms from benzene, furan, pyrrole, or thiophene. The condensed polycyclic aromatic group as Ar can be a condensed polycyclic aromatic hydrocarbon group or a condensed polycyclic aromatic heterocyclic group. Examples of fused polycyclic aromatic groups include residues derived from pyrene, coronene, triphenylene, naphthalene, or phenanthrene by removing two hydrogen atoms.

More specifically, Ar may be a divalent aromatic group represented by the following formula (10), (11) or (12).

In formula (10), X ¹ has the same definition as X ¹ in formula (I), and multiple X ¹ 's may be the same or different. X ² represents a monovalent substituent bonded to a carbon atom other than the carbon atom to which X ¹ of the aromatic ring is bonded, n1 represents an integer of 0 to 2, and n2 represents an integer of 0 to 6. , n3 are integers from 0 to 9. Multiple X ² may be the same or different. X ² may be, for example, a hydrocarbon group having 1 to 20 carbon atoms, a hydroxyl group, a nitro group, an amino group, a sulfo group, a cyano group, a silyl group, a phosphonic acid group, a diazo group or a mercapto group. X ¹ and X ² may be the same substituent. In these formulas, the carbon atom adjacent to the carbon atom to which ^X1 is bonded and having a bond corresponds to carbon atom ^C1 in formula (I).

The trivalent rare earth ion is not particularly limited, and can be appropriately selected according to the emission color and the like. Rare earth ions are, for example, Eu(III) ions, Tb(III) ions, Gd(III) ions, Sm(III) ions, Yb(III) ions, Nd(III) ions, Er(III) ions, Y ( It can be at least one selected from the group consisting of III) ions, Dy(III) ions, Ce(III) ions, and Pr(III) ions. Among them, from the viewpoint of obtaining high emission intensity, rare earth ions are selected from the group consisting of Eu(III) ions, Tb(III) ions, Yb(III) ions and Gd(III) ions, or Eu(III) ions, At least one selected from the group consisting of Tb(III) ions and Gd(III) ions may be used.

The rare earth compound may have two or more phosphine oxide ligands represented by formula (I), and may further have other ligands coordinated to the rare earth ion. Other ligands may be, for example, diketone ligands represented by the following formula (II).

In formula (II), ^R2 represents a hydrogen atom or a deuterium atom, ^R3 represents a hydrocarbon group which may have a substituent, and ^R2 and ^R3 are linked to form a cyclic group. may be Two R ² may be the same or different. R ³ may be an alkyl group or a halogenated alkyl group, and may have 1-10 carbon atoms. R ³ may be a fluoroalkyl group having 1 to 5 carbon atoms (eg, trifluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group).

Examples of the compound represented by the formula (II) in which R ² and R ³ are linked to form a cyclic group include camphor derivatives represented by the following formula (IIa) and enantiomers thereof is mentioned. Any ratio of the two enantiomers may be combined.

In formula (IIa), R ³ has the same definition as R ³ in formula (II). R ⁴ , R ⁵ and R ⁶ each independently represent an optionally substituted hydrocarbon group, R ⁷ , R ⁸ , R ⁹ and R ¹⁰ each independently represent a hydrogen atom, a halogen atom, or a substituted indicates a hydrocarbon group which may have a group.

R ⁴ , R ⁵ and R ⁶ may be optionally substituted alkyl groups and may have 1 to 5 carbon atoms. A specific example of R ⁴ , R ⁵ and R ⁶ is a methyl group.

R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may each independently be an optionally substituted alkyl group and may have 1 to 5 carbon atoms. R ⁷ , R ⁸ , R ⁹ and R ¹⁰ may be hydrogen atoms.

Specific examples of compounds represented by formula (IIa) and enantiomers thereof include 3-(trifluoroacetyl)camphorate and 3-(perfluorobutyryl)-(±)-camphorate.

A rare earth compound having two rare earth ions, two phosphine oxide ligands of formula (I), and a diketone ligand of formula (II) is represented, for example, by the following formula (III). As shown by formula (III), the aromatic group Ar tends to be in a staggered twisted configuration about the C ¹ -C ¹ bond.

A rare earth compound can be synthesized by a method combining ordinary reactions such as a reaction of exchanging ligands of existing rare earth compounds.

The rare earth compounds according to the embodiments described above can be used alone or in combination with other materials to form a luminous body that emits light efficiently even at high temperatures by utilizing its fluorescence properties. The emitters can be used in various light emitting devices such as LED, laser white light source modules. The driving temperature of light-emitting devices often exceeds 100° C., and rare earth compounds that maintain strong light emission at high temperatures are very useful. Furthermore, the rare earth compound according to the present embodiment is also useful as a wavelength conversion material or a security material that imparts encryption information to various materials such as plastic materials.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
Study 1
1-1. Synthesis of Rare Earth Compounds Phosphine oxide ligand Fdpbp
A phosphine oxide ligand Fdpbp was synthesized according to the following reaction scheme.

In an argon atmosphere, 4,4'-dibromooctafluorobiphenyl (5.2 g, 11.4 mmol) was placed in a flame-dried three-necked flask and dissolved in superdehydrated THF (70 mL). After cooling the inside of the flask to -80°C, n-butyllithium (1.6 M in hexane, 14 mL) was slowly added dropwise, and the reaction solution was stirred for 1 hour. Chlorodiphenylphosphine (4.4 mL, 23.8 mmol) was then added and the reaction was stirred for an additional hour. After allowing the reaction to warm to room temperature and stirring for 12 hours, the solvent was removed and the residue was extracted three times with methylene chloride and brine. The organic layer was oxidized with aqueous peroxide in an ice bath and then extracted from the organic layer with brine three times. Fdpbp (white powder, yield 40-50%) was obtained by reprecipitation with hexane.
^1H -NMR: (270 MHz, _CDCl3 , 25°C) δ 7.76-7.85 (8H, Ar), 7.59-7.66 (4H, Ar), 7.50-7.58 (8H, Ar) ppm.
IR (ATR): 1243 cm ^-1 (st, P=O)

Rare earth compound _Eu2 (hfa) ₆ (Fdpbp) ₂
Fdpbp (349.6 mg, 0.5 mmol) was placed in an eggplant-shaped flask and dissolved in heated chloroform (20 mL). Eu(hfa) ₃ ( _H2O ) ₂ (406.8 mg, 0.5 mmol) was dissolved in methanol (20 mL) in a separate vessel. The methanol solution was added dropwise to the chloroform solution of Fdpbp and heated under reflux for 12 hours. Then, Eu ₂ (hfa) ₆ (Fdpbp) ₂ (colorless transparent crystals, 300 mg, yield 41%) was obtained by recrystallization from the reaction solution.
IR (KBr) : 1655 cm ^-1 (st, C=O),1255 cm ^-1 (st, P=O)
ESI-MS mass m/z = 2965.92 [M+Na] ⁺

1-2. X-ray diffraction
From the results of X-ray diffraction of a single crystal of _Eu2 (hfa) ₆ (Fdpbp) ₂ , the two tetrafluorophenylene groups of the phosphine oxide ligand Fdpbp bound to the two Eu ions are shown in the formula above. It was suggested that a stable structure is formed that is arranged in a staggered twisted orientation so that the

1-3. Thermogravimetric/differential thermal analysis (TG-DTA)
FIG. 1 is a graph showing the results of thermogravimetric and differential thermal analysis of Eu ₂ (hfa) ₆ (Fdpbp) ₂ . It was confirmed that Eu ₂ (hfa) ₆ (Fdpbp) ₂ exhibits a high decomposition temperature exceeding 300°C.

1-4. Luminescence excitation spectrum
Emission excitation spectra of Eu ₂ (hfa) ₆ (Fdpbp) ₂ were measured. FIG. 2 is an emission excitation spectrum of Eu ₂ (hfa) ₆ (Fdpbp) ₂ at 25°C. Furthermore, an emission spectrum at 200° C. was also measured. Figure 3 is the emission spectrum of _Eu2 (hfa) ₆ (Fdpbp) ₂ at 25°C and 200°C. At 200° C., Eu ₂ (hfa) ₆ (Fdpbp) ₂ maintained an emission intensity of 70% or more compared to the value at room temperature.

A europium complex polymer having repeating units formed by ligands TCPO and dpbp represented by the following formula, ligand hfa, and Eu ions was prepared. 3-(Trifluoromethylhydroxymethylene)-(+)-camphorate (+facam) was also prepared, and a europium complex having this and hfa as a ligand was prepared. For these and Eu ₂ (hfa) ₆ (Fdpbp) ₂ , changes in luminescence intensity with temperature were measured.

FIG. 4 is a graph showing the relationship between the emission intensity at a wavelength of 613 nm and the temperature for various rare earth compounds. The vertical axis is a relative value to the emission intensity at 25°C. It was confirmed that Eu ₂ (hfa) ₆ (Fdpbp) ₂ shows less decrease in emission intensity at high temperatures than other rare earth complexes.

Consideration 2
2-1. Synthesis of Rare Earth Compounds Rare Earth Compounds Tb ₂ (hfa) ₆ (Fdpbp) ₂
Fdpbp (349.6 mg, 0.5 mmol) was placed in an eggplant-shaped flask and dissolved in heated chloroform (20 mL). Tb(hfa) ₃ ( _H2O ) ₂ (407.0 mg, 0.5 mmol) was dissolved in methanol (20 mL) in a separate vessel. The methanol solution was added dropwise to the chloroform solution of Fdpbp and heated to reflux for 12 hours. Thereafter, Tb ₂ (hfa) ₆ (Fdpbp) ₂ (colorless transparent crystals, 350 mg, yield 47%) was obtained by recrystallization from the reaction solution.
IR (KBr) : 1655 cm ^-1 (st, C=O),1253 cm ^-1 (st, P=O)
ESI-MS mass m/z = 2979.92 [M+Na] ⁺

Rare earth compound _Yb2 (hfa) ₆ (Fdpbp) ₂
Fdpbp (349.6 mg, 0.5 mmol) was placed in an eggplant-shaped flask and dissolved in heated chloroform (20 mL). Yb(hfa) ₃ ( _H2O ) ₂ (407.5 mg, 0.5 mmol) was dissolved in methanol (20 mL) in a separate vessel. The methanol solution was added dropwise to the chloroform solution of Fdpbp and heated under reflux for 12 hours. Thereafter, Yb ₂ (hfa) ₆ (Fdpbp) ₂ (colorless transparent crystals, 270 mg, yield 35%) was obtained by recrystallization from the reaction solution.
IR (KBr) : 1653 cm ^-1 (st, C=O),1253 cm ^-1 (st, P=O)

2-2. Luminescence excitation spectrum
Emission spectra of Tb ₂ (hfa) ₆ (Fdpbp) ₂ and Yb ₂ (hfa) ₆ (Fdpbp) ₂ at 25° C. (excitation light: 350 nm) were measured. FIG. 5 shows emission excitation spectra of _Eu2 (hfa) ₆ (Fdpbp) ₂ , _Tb2 (hfa) ₆ (Fdpbp) ₂ and _Yb2 (hfa) ₆ (Fdpbp) ₂ at 25°C. The Tb compound emitted green light, the Eu compound emitted red light, and the Yb compound emitted light in the infrared region.

Claims (5)

two trivalent rare earth ions;
Formula (I) below:

wherein C ¹ , C ² and C ³ represent carbon atoms, Ar includes C ¹ , C ² and C ³ and optionally has a substituent other than X ¹ , a bivalent monocyclic aromatic represents a aromatic group or condensed polycyclic aromatic group, and X ¹ is a halogen atom, an optionally substituted hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted alkoxy group, a substituted optionally substituted alkoxycarbonyl group, optionally substituted alkanoyloxy group, optionally substituted aryloxy group, optionally substituted aryloxycarbonyl optionally substituted arylcarbonyloxy group, hydroxyl group, carboxyl group or cyano group, R ¹ is an optionally substituted aromatic group, or linear or cyclic aliphatic group wherein multiple Ar, X ¹ and R ¹ in the same molecule contain two phosphine oxide ligands, each of which may be the same or different,
Ar is the following formula (10) or (11):

is a divalent aromatic group represented by, in formulas (10) and (11), X ¹ is synonymous with X ¹ in formula (I) , and a plurality of X ¹ may be the same or different Well, X ² represents a monovalent substituent bonded to a carbon atom other than the carbon atom to which X ¹ of the aromatic ring is bonded, n1 represents an integer of 0 to 2, n2 represents an integer of 0 to 6 and a plurality of X ² may be the same or different, and the carbon atom adjacent to the carbon atom to which X ¹ is bonded and having a bond is C ¹ in formula (I) ,
A rare earth compound wherein two said rare earth ions are linked by two said phosphine oxide ligands coordinated to both of them. A light emitter comprising the rare earth compound according to claim 1 . A light emitting device comprising the light emitter of claim 2 . A wavelength conversion material comprising the rare earth compound according to claim 1 . A security material comprising the rare earth compound of claim 1 .

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