JP4702887B2 - Luminescent rare earth nine-nuclear complex - Google Patents

Description

  The present invention relates to a rare earth complex that emits fluorescence when irradiated with predetermined excitation light, and particularly relates to a light-emitting rare earth polynuclear complex in which one complex molecule has a plurality of nuclei of rare earth ions.

Photosensitized luminescent rare earth complexes are expected to be used as luminescent centers for photofunctional molecules that can be used as reagents for LEDs (Light Emitting Diodes) and biological component analysis (immunoassay). In recent years, many studies have been conducted. For example, to construct a complex system that can realize efficient emission by small sample, high molar extinction coefficient, and compounds having ³ hooters * transition level is higher benzophenone skeleton in the excited state, an organic such as pyridine derivatives Many ligands have been designed and synthesized. In addition, studies on the color tone of color development have also been conducted. For example, in the patent document 1, the present inventors disclosed a transparent solid containing both a first complex whose central ion is europium and a second complex whose central ion is terbium. A white light source with high color rendering properties or a light emitting device capable of emitting light of any color based on an optical functional material made of a carrier is disclosed.

  However, the luminescent rare earth complex still has problems to be solved, such as improvement of emission intensity and improvement of thermal durability. As an example, generation of a green light emitting complex having high emission intensity and heat durability has not yet been realized. The cause is thought to be that the energy level in the ligand of the complex does not match that of the rare earth ion, but diketone and bipyridine, which are currently used in general, match the energy level. There is a problem that is difficult.

  The present inventors have conceived a multinuclear complex in which one molecule is composed of a plurality of nuclei of rare earth ions as a method for imparting heat durability. Furthermore, the present inventors have found a salicylic acid ester capable of efficiently photosensitizing Tb (III) as a ligand for creating a green light emitting Tb (III) complex exhibiting high emission intensity. Thereby, in the luminescent complex synthesized by the present invention, the energy level of the ligand matches the emission level of Tb (III), and high intensity green emission can be realized. Most of the luminescent rare earth complexes that have been studied and disclosed so far are mononuclear complex systems, and few studies have been conducted on polynuclear complex systems.

JP 2003-147346 A

  The problem to be solved by the present invention is to provide a light-emitting rare earth complex that has high emission intensity, has heat durability, and can be produced at low cost.

In order to solve the above-mentioned problems, the present inventors have conducted research on a light-emitting rare earth polynuclear complex, and as a result, have found a rare earth complex having unprecedented high emission intensity and high heat durability. The luminescent rare earth nine- nucleus complex according to the present invention thus formed is
Complex structure is formula: (L) ₁₆ Ln ₉ X _c
[L is the formula:
(Where R is an alkyl group having 1 to 20 carbon atoms )
A ligand having a photosensitizing function represented by:
Ln is any one or a combination of samarium, europium, gadolinium, terbium, ytterbium trivalent cations ,
X is _{NO 3, Cl, Br, OH} , any one of _{BPh 4, PF 6, ClO 4} , _{or, NO 3, Cl, Br,} OH, any of the BPh _4, PF _6, ClO ₄ Any one or a combination of OH, SH, NO ₃ , Cl, Br, BPh ₄ , PF ₆ , ClO ₄ ,
c is an integer of 3 ≦ c ≦ 8 ,
In each ligand L, —OH and ═O are coordinated to the same or different Ln.]
It is represented by.

The luminescent rare earth nine- nucleus complex of the present invention has a remarkably higher emission intensity than conventional light-emitting elements, and can be efficiently excited using a commercially available inexpensive LED. Moreover, heat durability is also high. Moreover, the synthetic raw material is inexpensive. In addition, since the light-emitting rare earth nine- nuclear complex itself is colorless and transparent, it can be easily integrated with other substances and materials, and can be applied in various fields.

The light-emitting rare earth polynuclear complex according to the present invention is obtained by coordinating a ligand molecule having a photosensitizing function to rare earth ions serving as a plurality of nuclei, wherein the rare earth ions are Ln and the ligands are L. , an atom linking the rare earth ions with each other when the X, represented by the general formula _{L a (Ln) b X c} .

  In the general formula, a is an integer of 1 to 40, b is an integer of 2 to 20, c is an integer of 1 to 40, and 1 ≦ a / b ≦ 4 and 1 <b / c ≦ 4. Have.

The rare earth ions that can be used in the present invention are not particularly limited. For example, divalent cation: europium Eu ²⁺ , trivalent cation: lanthanum La ³⁺ , cerium Ce ³⁺ , praseodymium Pr ³⁺ , neodymium Nd ³⁺ , promethium Pm ³⁺ , samarium Sm ³⁺ , europium Eu ^{3 +} , Gadolinium Gd ³⁺ , terbium Tb ³⁺ , dysprosium Dy ³⁺ , holmium Ho ³⁺ , erbium Er ³⁺ , thulium Tm ³⁺ , ytterbium Yb ³⁺ , lutetium Lu ³⁺ , tetravalent cation: cerium Ce ^{4 +} Can be used.

  The nucleus forming the multinuclear complex may be composed of only one kind of these rare earth ions, or a plurality of kinds of rare earth ions may be combined. Since the light emission characteristics and the like vary depending on the type of rare earth ion, it is selected according to the purpose.

A ligand is a photosensitizer that transfers the energy of irradiated light to rare earth ions. The ligand that can be used in the present invention has the following formula:
It is represented by

In the above formula, R _{1 to} R ₅ are each an aromatic group containing a hetero atom such as hydrogen, a hydroxyl group, a thienyl group, or a pyridyl group, an alkyl group having a branched chain structure such as a benzyl group or an isopropyl group, or a substituted or unsubstituted amino group. Group, substituted or unsubstituted aryl group, nitro group, chloro group, bromo group, cyano group, alkyl group or cycloalkyl group represented by -R, alkoxy group represented by -OR, or -C (= O) R And an amide group represented by —C (═O) NHR. Here, R is a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms or a cycloalkyl group. Examples of the aryl group in the present specification include a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a naphthyl group, an anthryl group, and a phenanthryl group. When the aryl group is substituted, examples of the substituent include an alkyl group, a halogen, a nitro group, a cyano group, an alkoxy group, and an acyl group.

In the above formula, Y ₁ is —OH, Y ₂ is ═O, and Y ₁ and Y ₂ are coordinated to the rare earth ion, whereby the ligand and the rare earth ion are coordinated. As for the coordination form, both Y ₁ and Y ₂ may be coordinated to the same rare earth ion, or Y ₁ and Y ₂ may be coordinated to separate rare earth ions.

Further, in the present invention, a ligand that can obtain high emission intensity and is easily synthesized is represented by the formula:
It is preferable to use hexyl salicylate represented by: Since this hexyl salicylate has a feature that its absorption spectrum is around 390 nm, it can be efficiently excited by light from a commercially available inexpensive LED or the like. Furthermore, it is characterized by being much easier to synthesize and less expensive than the ligands of rare earth complexes that have been used conventionally.

  Further, for the same reason as described above, methyl salicylate can be used as a ligand.

X, which is an atom that links rare earth ion atoms, is an ion that links rare earth ion atoms (for example, O, OH, S, SH, Se, Te) or a counter ion that is part of the composition (for example, NO ₃ , Cl , Br, OH, BPh ₄ , PF ₆ , ClO ₄ ), or a plurality of combinations.

In a preferred embodiment of the present invention, a nine-nuclear rare earth polynuclear complex having a complex structure represented by the formula: (L) ₁₆ Ln _{9 Xc} can be used (FIG. 1). In this case, the ligand is coordinated to the outer eight of the nine rare earth ions (nuclei). At this time, the rare earth ions may be any one of trivalent cations of samarium, europium, gadolinium, terbium, ytterbium, or a combination thereof.

  By using only terbium as the rare earth ion serving as the nucleus of the above nine-nuclear rare earth complex and using hexyl salicylate as the ligand, it is possible to realize green light emission with high durability and high light emission intensity. In addition, yellow light emission can be realized by combining terbium and europium as rare earth ions. Thus, light emission of a desired color can be obtained by appropriately combining various rare earth ions.

  Hereinafter, in the Examples, among the luminescent rare earth polynuclear complexes according to the present invention, the nine-nuclear complex will be described in detail.

<Complex synthesis>
A nine-nuclear rare earth polynuclear complex was produced using Ln (NO ₃ ) ₃ · 6H ₂ O (Ln: Sm, Eu, Gd, Tb, Yb). Generation when the rare earth ion was Tb was performed as follows.
Hexyl salicylate (0.600 g, 2.70 mmol) in methanol solution 50ml equimolar amount of triethylamine (0.270 g, 2.70 mmol) was added and after stirring at room temperature for a predetermined _{time, Tb (NO 3) 3 ·} 6H 2 O (0.690g , 1.52 mmol) methanol solution is added dropwise and stirred at 40 ° C. for 2 hours (FIG. 2). The resulting clear solution is filtered and left to obtain white crystals. The crystals are washed several times with cold methanol, filtered and air dried.

<Identification of complex>
The white crystal produced | generated by the said method was identified.
The results of elemental analysis and FAB (Fast Atom Bombardment: Fast Atom Bombardment) -MASS spectrum measurement are shown (FIGS. 3 and 4). The FAB-MASS spectrum measurement confirmed the presence of fragment peaks corresponding to [Ln ₉ (L) ₁₆ (OH) ₁₀ ] ⁺ , and revealed that the composition was similar even when the type of rare earth ions changed. It was. In the measurement, N atoms were contained in all the complexes, but all were 0.3% or less.
In addition to these measurements, DSC (Differential Scanning Calorimetry) measurement, NMR (Nuclear Magnetic Resonance) measurement, and IR (InfraRed) measurement were also performed.

・ As a result of DSC measurement, no peak was detected in the vicinity of 100 to 150 ° C., and it was confirmed that no coordination water or crystallization water was contained.
・ From the result of ¹ H-NMR measurement, hydrogen of the alkyl chain of hexyl salicylate and other peaks derived from the ligand could be assigned ( ¹ H-NMR (CDCl ₃ ): δ10.9 (1H), δ7 .9-6.9 (4H), δ4.3 (2H), δ1.8 (2H), δ1.4 (6H), δ0.9 (3H)).
・ As a result of IR measurement, a strong peak derived from CH bond was observed near 2800 cm ⁻¹ , suggesting that the ligands were not decomposed in these nine-nuclear complexes. Further, NO ₃ ⁻ contained in the composition could be attributed to a peak of 1380 cm ⁻¹ (FIG. 5). For Tb (III), chelate titration with EDTA was performed, and results consistent with the estimated composition were obtained (Found 26.54%, Cal. 26.52%).

From these measurement results, all the synthesized complexes are composed of Ln ₉ (L) ₁₆ (OH) ₁₀ (NO ₃ ) (CH ₃ OH) _n (Ln: Sm, Eu, Gd, Tb, Yb). It was confirmed to be a nuclear complex.

<Thermal stability of Tb (III) nine-nuclear complex>
The thermal stability of hexyl salicylate-Tb (III) nine-nuclear complex was revealed by DSC measurement. From the result of DSC measurement (FIG. 6), it was found that the complex was stable up to about 300 ° C. This data shows that the hexyl salicylate-Tb (III) nine-nuclear complex has a thermal durability higher by 50 ° C. or more than the conventional mononuclear luminescent rare earth complex.

<Luminescent properties of Tb (III) nine-nuclear complex>
A hexyl salicylate-Tb (III) nine-nuclear complex sample was dissolved in methanol (1 × 10 ⁻⁴ M) and subjected to N ₂ bubbling, and then luminescence characteristics were measured. The excitation wavelength was 380 nm corresponding to the π-π * transition of the ligand. FIG. 7A shows an emission spectrum of hexyl salicylate-Tb (III) nine-nuclear complex in methanol, and FIG. 7B shows an excitation spectrum. Peaks based on the transition of Tb (III) from ⁵ D _{4 to} ⁷ F _J (J = 0, 1, 2, 3, ₄ , ⁵ , ⁶ ) were observed.

In order to confirm that this luminescence was due to photosensitization, the emission lifetime of the complex was measured by 380 nm excitation, which is ligand excitation. Luminescence was detected at 545 nm corresponding to the ⁵ D ₄ → ⁷ F ₅ transition of Tb (III) emission. A decrease in light emission was observed, and it was found that light was emitted by photosensitization. By first regressing ln [Intensity] vs. time [ms], the emission lifetime derived from Tb (III) was estimated to be 1.20 ms (FIG. 8).

  Next, methyl salicylate-nine nucleus complex was synthesized using methyl salicylate as a ligand. The results of elemental analysis and mass spectrometry in this case are shown in the table of FIG. Further, luminescence measurement was performed under the same conditions as in the case of the hexyl salicylate-Tb (III) nine-nuclear complex (FIG. 10). Similar to the hexyl salicylate-nuclear complex, luminescence derived from Tb (III) was clearly observed.

On the other hand, luminescence measurements of conventionally known mononuclear complexes Tb (acac) ₃ (H ₂ O) ₂ and Tb (hfac) ₃ (H ₂ O) ₂ were performed (acac: acetylacetonate, hfac). : Hexafluoroacetylacetonate). Luminescence could not be detected under the measurement conditions of complex concentration: 1 × 10 ⁻⁴ M, excitation wavelength: 390 nm, in methanol.

The light-emitting rare earth nine- nuclear complex according to the present invention is an ink composition that takes advantage of the characteristic that it is colorless under normal visible light and emits light in an arbitrary color according to the type of green or rare earth ions under ultraviolet irradiation. It can be applied to. By using this ink composition, it is possible to perform marking and numbering that are difficult to be visually recognized in a normal state on various articles. For example, it can be applied to a customer barcode printed on mail. Further, since it is possible to write or print so-called hidden characters or hidden symbols on a document, it is possible to provide a security function to the substrate.

When the light-emitting rare earth nine- nucleus complex according to the present invention is applied to a printing ink composition, it is applied to offset printing ink, gravure printing ink, silk screen printing ink, inkjet printing ink, writing instrument ink, etc. It is possible to apply. In addition, various additives such as a solvent, a binder (mainly resins), a penetrating agent, an antifoaming agent, a coloring agent, and a dispersing agent may be used in the ink composition as necessary.

It is also possible to obtain a resin composition (including a resin film) containing the light-emitting rare earth nine- nucleus complex according to the present invention. These resin compositions and the like can be applied to fields that use vivid colors such as toys, stage equipment, interior decorations, and show windows.

Resins that can be used in combination with the light-emitting rare earth nine-nuclear complex according to the present invention are optically transparent or opaque, such as polyvinyl alcohol, polyvinyl butyral, diethylene glycol bisallyl carbonate resin, poly (methyl) meta. Acrylate and its copolymer, polyvinyl acetate, cellulose (including paper) polyester, polycarbonate, polystyrene and its copolymer, epoxy resin, nylon resin, polyurethane, etc., and these can be used as a binder for ink composition. Used as needed.

The conceptual diagram of the luminescent rare earth polynuclear complex which concerns on this invention. The figure which shows the production | generation method of Tb (III) nine nucleus complex. The table | surface which shows the elemental-analysis result of the luminescent rare earth polynuclear complex which concerns on this invention. The graph which shows the result of the FAB-MASS spectrum measurement of a Tb (III) nine-nuclear complex. The graph which shows the result of IR measurement of Tb (III) nine-nuclear complex. The graph which shows the result of DSC measurement. (A) Emission spectrum and (b) Excitation spectrum of hexyl salicylate-Tb (III) nine-nuclear complex in methanol. The graph which shows the light emission lifetime of a hexyl salicylate-Tb (III) nine-nuclear complex. The table | surface which shows the elemental analysis and mass spectrometry result of a methyl salicylate-Tb (III) nine-nuclear complex. The graph which shows the emission spectrum of a methyl salicylate-Tb (III) nine-nuclear complex.

Claims (5)

Complex structure is formula: (L) ₁₆ Ln ₉ X _c
[L is the formula:
(Where R is an alkyl group having 1 to 20 carbon atoms )
A ligand having a photosensitizing function represented by:
Ln is any one or a combination of samarium, europium, gadolinium, terbium, ytterbium trivalent cations ,
X is _{NO 3, Cl, Br, OH} , any one of _{BPh 4, PF 6, ClO 4} , _{or, NO 3, Cl, Br,} OH, any of the BPh _4, PF _6, ClO ₄ Any one or a combination of OH, SH, NO ₃ , Cl, Br, BPh ₄ , PF ₆ , ClO ₄ ,
c is an integer of 3 ≦ c ≦ 8 ,
In each ligand L, —OH and ═O are coordinated to the same or different Ln.]
A light-emitting rare earth nine- nucleus complex characterized by the following: L is the formula:
The luminescent rare earth nine- nucleus complex according to claim 1, which is a ligand represented by the formula: The luminescent rare earth nine- nucleus complex according to claim 1, wherein L is methyl salicylate. An ink composition comprising the luminescent rare earth nine- nucleus complex according to any one of claims 1 to 3 . The resin composition which comprises the luminescent rare earth nine- nucleus complex in any one of Claims 1-3 .