KR101658805B1 - Lanthanide complex and invisible fluorescent ink - Google Patents

Abstract

A lanthanide complex of a novel structure is disclosed, wherein the lanthanum complex is not distinguishable under visible light, and when irradiated with ultraviolet light and X-ray, green luminescence is caused. Especially, ultraviolet and X- And has a thermoluminescence characteristic that causes green light emission at a high temperature. Therefore, it is useful as an invisible light-emitting ink.

Description

Lanthanide complexes and a lanthanide complex and invisible fluorescent ink containing the same,

The present invention relates to a lanthanide complex and an incoherent luminescent ink containing the lanthanide complex. The lanthanide complex and the incoherent luminescent ink containing the lanthanide complex are improved in ultraviolet ray or X-ray irradiation.

In general, various special elements such as luminescent color yarn, luminescent ink, discoloration ink, optical interference pattern, and time varying material are used to prevent forgery and alteration of banknotes, securities, passport identity information, , Silver, partially exposed silver wire, etc. are used. For example, a thermally sensitive ink having characteristics that if the color of the ink is instantaneously extinguished when heated to about 50 to 70 ° C by friction or heat and is restored to its original color when a heat source is removed, And a photosensitive ink that discolors were developed. It is already known that a liquid crystal, an organic or inorganic material is produced as a material exhibiting such a heat discoloring effect and is partially used for industrial paints or pamphlets, stickers, ornaments and the like.

For example, a rare earth element and an organic acid-containing compound which emit light when irradiated with an electron beam, an X-ray or an ultraviolet ray are known. However, these compounds can not accumulate energy during ionization irradiation and thus are difficult to be used as a heat radiator. And energy can not be accumulated. Therefore, there is a problem that it can not be used as a thermo-sensitive light-emitting body when irradiating ultraviolet rays and X-rays.

On the other hand, there is known a transparent organic light emitting composition for recording hidden data which can not be identified under visible light and can be decrypted through a separate mechanical device for preventing falsification and modulation on a document. However, such a transparent organic light emitting composition has a disadvantage of complicating document verification because it has a wide wavelength emission range, and in particular, does not emit light under X-ray.

The first problem to be solved by the present invention is to provide a lanthanide complex having excellent luminescence properties.

A second problem to be solved by the present invention is to provide an invisible light-emitting ink containing the lanthanide complex.

According to an aspect of the present invention,

A lanthanide complex of formula (1)

≪ Formula 1 >

In the formula,

Ln represents a lanthanide metal;

The CyN is a substituted or unsubstituted heteroaryl group having 3 to 60 carbon atoms and containing nitrogen bonded to Ln or a heterocyclic group having 3 to 60 carbon atoms or a substituted or unsubstituted heteroaryl group containing nitrogen bonded to Ln, Group;

The CyN-CyN represents a cyclometalating ligand bound to Ln via nitrogen;

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ are each independently selected from the group consisting of hydrogen, hydroxyl, sulfo, halogen, carboxyl, amino, nitro, cyano, A substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₁ -C ₂₀ alkoxy group, a substituted or unsubstituted C ₂ -C ₂₀ alkenyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkynyl group, a C ₁ -C ₂₀ heteroaryl group, a substituted or unsubstituted C ₆ -C ₃₀ aryl group, a substituted or unsubstituted C ₆ -C ₃₀ aryloxy group, a substituted or unsubstituted C ₂ -C ₂₀ alkoxycarbonyl, Substituted or unsubstituted C ₁ -C ₂₀ acyloxy, substituted or unsubstituted C ₁ -C ₂₀ acylamino, substituted or unsubstituted C ₂ -C ₂₀ alkoxycarbonylamino, substituted or unsubstituted C ₇ -C ₃₀ aryl oxy carbonylamino, sulfonylamino group, sulfamoyl group, carbamoyl group, a substituted or unsubstituted C ₆ -C ₃₀ arylthio group, a substituted or unsubstituted C3-C30 H. A substituted or unsubstituted C4-C30 cycloalkyl group, a substituted or unsubstituted C4-C30 cycloalkyl group, a substituted or unsubstituted C4-C30 cycloalkyl group, a substituted or unsubstituted C4-C30 cycloalkyl group , A substituted or unsubstituted C ₇ -C ₃₀ arylalkyl group, a substituted or unsubstituted C ₅ -C ₃₀ heteroaryl group, or a substituted or unsubstituted C ₃ -C ₃₀ heteroarylalkyl group;

M and n are integers from 1 to 3, and m + n = 3;

X represents an integer of 1 to 10;

According to a preferred embodiment, the lanthanide complex of formula (1) may be a compound of formula (2): < EMI ID =

According to a second aspect of the present invention,

There is provided an invisible light-emitting ink comprising a lanthanide complex of Formula 1 and a solvent.

According to a preferred embodiment, the weight of the lanthanide complex of Formula 1 may be 0.001 to 1% by weight based on the total weight of the non-visible light emitting ink.

The lanthanum complex according to Formula (1) generates green light when irradiated with ultraviolet rays or X-rays even at a low concentration and accumulates ultraviolet rays or X-ray irradiation energy to generate thermoluminescence upon post heating. Therefore, it can be usefully used as a non-visible light-emitting ink for recording a secret data or means for preventing forgery and modulation.

Hereinafter, the present invention will be described in detail.

The lanthanide complex according to an embodiment of the present invention has a structure represented by the following formula (1)

≪ Formula 1 >

In the formula,

Ln represents a lanthanide metal;

The CyN is a substituted or unsubstituted heteroaryl group having 3 to 60 carbon atoms and containing nitrogen bonded to Ln or a heterocyclic group having 3 to 60 carbon atoms or a substituted or unsubstituted heteroaryl group containing nitrogen bonded to Ln, Group;

The CyN-CyN represents a cyclometalating ligand bound to Ln via nitrogen;

Wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ are each independently selected from the group consisting of hydrogen, hydroxyl, sulfo, halogen, carboxyl, amino, nitro, cyano, A substituted or unsubstituted C ₁ -C ₂₀ alkyl group, a substituted or unsubstituted C ₁ -C ₂₀ alkoxy group, a substituted or unsubstituted C ₂ -C ₂₀ alkenyl group, a substituted or unsubstituted C ₂ -C ₂₀ alkynyl group, a C ₁ -C ₂₀ heteroaryl group, a substituted or unsubstituted C ₆ -C ₃₀ aryl group, a substituted or unsubstituted C ₆ -C ₃₀ aryloxy group, tooth ring or unsubstituted C ₂ -C ₂₀ alkoxycarbonyl , Substituted or unsubstituted C ₁ -C ₂₀ acyloxy, substituted or unsubstituted C ₁ -C ₂₀ acylamino, substituted or unsubstituted C ₂ -C ₂₀ alkoxycarbonylamino, substituted or unsubstituted C ₇ -C ₃₀ aryloxy carbonylamino, sulfonylamino group, sulfamoyl group, carbamoyl group, a substituted or unsubstituted C ₆ -C ₃₀ arylthio group, a substituted or unsubstituted C3-C30 A substituted or unsubstituted C4-C30 cycloalkyl group, a substituted or unsubstituted C4-C30 cycloalkyl group, a substituted or unsubstituted C4-C30 cycloalkyl group, a substituted or unsubstituted C4-C30 cycloalkyl group , A substituted or unsubstituted C ₇ -C ₃₀ arylalkyl group, a substituted or unsubstituted C ₅ -C ₃₀ heteroaryl group, or a substituted or unsubstituted C ₃ -C ₃₀ heteroarylalkyl group;

M and n are integers from 1 to 3, and m + n = 3;

X represents an integer of 1 to 10;

In the lanthanum complex of Formula 1, Ln represents a lanthanide-based metal, for example, Tb _a Er _1-a , and a represents 0 to 0.9, preferably 0.1 to 0.9.

Examples of the cyclometalated ligands CyN-CyN include 1,10-phenanthroline and the like.

The compound of formula (1) can not be identified under visible light, but generates green light when irradiated with ultraviolet rays or X-rays. In particular, when the ultraviolet ray or X-ray is irradiated for a predetermined time, this energy is accumulated to cause thermo-thermal emission upon post-heating, and it becomes possible to display the secret data, that is, a predetermined shape, character or pattern not visible under visible light. Since the secret data can be clearly displayed due to the heat emission, it is possible to effectively prevent falsification and modulation.

Preferable examples of the above-mentioned formula (1) include the following compounds:

(2)

In the formula,

_{Ln, R 1 ~ R 7,} m, n and x are as defined above.

According to a preferred embodiment, the lanthanide complex of formula (1) may be a compound of formula (2): < EMI ID =

(3)

In the formula,

Ln represents Tb _a Er _1-a , and a represents 0 to 0.9.

In the structural formula (3), a is in the range of 0.1 to 0.9.

The compound of Formula 1 may be prepared by reacting a nitrate of at least one lanthanide metal in an acidic medium containing a nitric acid solution with an alcohol solution of a nitrogen-containing heteroaromatic compound as an organic ligand.

Specifically, in a nitric acid-containing solution having a pH of 1 to 2.5, a nitrate of a lanthanide metal as a central metal component is mixed with acetylacetone and a nitrogen-containing heteroaromatic compound in a predetermined ratio. Then, the pH of the reactant is adjusted to 6.5 to 7 using a base, and the reaction is carried out for 0.1 to 5 hours, preferably 0.3 to 0.7 hours. The obtained precipitate is then filtered by a conventional method to obtain a lanthanide complex ≪ / RTI >

In the above production process, an appropriate pH for obtaining a precipitate of the desired lanthanum complex of formula (1) is preferably from 6.5 to 7. When the pH is 6.5 or less, precipitates of the complex are incompletely formed. When the pH is 7 or more, Partial hydrolysis of the precipitate may occur. The precipitate of the lanthanide complex further undergoes a washing and drying process in subsequent processes.

As the solvent used in the above reaction, an aqueous solvent, an organic solvent or a mixture thereof may be used. For example, a mixed solvent of water and alcohol, for example, a mixed solvent of water and ethanol, may be used.

As the nitrate of the lanthanide metal used in the reaction, at least one lanthanide metal nitrate selected from Er, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Tm or Yb can be used. Preferably, terbium nitrate and erbium nitrate can be used. In this case, the molar ratio of terbium to erbium is preferably 1: 0.1 to 0.9.

The substituted or unsubstituted acetylacetone used in the reaction means that at least one hydrogen atom contained in acetylacetone is substituted or unsubstituted by a functional group, for example, unsubstituted acetylacetone may be used.

As the nitrogen-containing heteroaromatic compound used in the reaction, 1,10-phenanthroline and the like can be used.

The precursor of the lanthanum metal used in the reaction, substituted or unsubstituted acetylacetone, and the nitrogen-containing heteroaromatic compound may be used in a predetermined ratio, for example, 1: 0.1 to 5: 0.1 to 5, such as 1: 2: Can be used.

The lanthanum complex of Formula 1 prepared as described above may be added as a light emitting material to an incoherent light-emitting ink for recording confidential data such as forgery and modulation. In this case, the addition amount may be 0.001 to 1% by weight, for example, 0.001 to 0.05% by weight based on the total ink weight. When the content is less than 0.001% by weight, sufficient light emission intensity can not be obtained when irradiated with ultraviolet rays or infrared rays, and when the content is more than 1% by weight, there is a fear that the un-dissolved components are increased due to low solubility.

The invisible luminescent ink containing the compound of the formula (1) can be used to store confidential data in various documents, banknotes, securities, ID cards, passports, etc., which are required to prevent forgery and tampering.

The nonvisible light-emitting ink exhibits green light when irradiated with ultraviolet rays or X-rays, and it is also possible to accumulate ultraviolet rays or X-ray irradiation energy at a low temperature and display thermo-luminescence in a post-heating process. Therefore, when the nonvisible light ink is applied, a high level of protection against falsification and modulation becomes possible, and such various kinds of light emission can be performed independently of each other.

The nonvisible light-emitting ink includes a solvent for dissolving the lanthanide complex of Formula 1, and examples of the solvent include dioxane, acetone, and the like. The solvent may be used in an amount sufficient to dissolve the lanthanide complex of formula (1), and is not particularly limited.

The invention will be described in more detail with reference to the following examples, but the invention is not limited thereto.

Example 1

1 mmol (0.453 g) of Tb (NO) ₃ * 6H ₂ O and 1 mmol (0.461 g) of Er (NO) ₃ * 6H ₂ O were dissolved in 5 ml of distilled water, separately 4 mmol (0.792 g) Were dissolved in 15 ml of 96% ethanol and mixed. To this was added 4 mmol (0.400 ml) of acetylacetone.

The solution was stirred vigorously, nitric acid was added dropwise to adjust the pH to 2, and then the pH was adjusted to 6 by adding 25% caustic ammonia. The resulting microcrystalline precipitate was filtered, washed with 30 ml of a 1: 1 mixture of water and ethanol and dried in the atmosphere for one day. The yield of the product was 71.5%.

The structure of the product was analyzed by elemental analysis, IR, emission spectrum and X-ray crystallography.

The product samples were subjected to X-ray impact and UV-irradiation (unfiltered light generated in the mercury lamp DRT-250) by a URS-01 (25 kV, 20 mA, Ni-anticathode) through a window made of a foil Respectively. The X-ray pattern of the product was filmed with diffractometer DRON 2.0 in CuK _alpha -irradiation. The resulting product was compared with Ln (NO ₃ ) H ₂ O, Ln (Acac) ₃ Phen, and other analogues to confirm the structure, and no impurities were found.

The IR absorption spectrum of the product was measured with a Perkin-Elmer 522 at a wavelength of 400-4,000 cm ^-1 . The sample for measurement was prepared in the form of a suspension in liquid petrolatum. The results of IR spectra show the bi-dentate nature of the NO ₃ functionality (producing splitting / ν ₁ - ν / 180 cm ^-1 ). The coordination of 1,10-phenanthroline was confirmed by splitting the strip of deformation vibration? (CH) in the region of 850 cm-1 to 850 and 860 cm-1 (Spacu P. et al., Rev. Roum Chim., 1972, V.17, N4, p. 697).

A low-temperature emission spectrum was obtained using an SDL-1 apparatus, and a mercury lamp DRSh-250 was used for irradiation.

The luminescence spectrum of the product was distinguished from the known 1,10-phenanthroline-containing terbium acetylacetonate and erbium acetylacetonate by the property of splitting the strip and the property of dispersing the strength. The strongest line in the emission spectrum of the product was terbium ions ⁵ D ₄ - was matched to the transfer of the ⁷ F _5. The half-width of the line is about 3 nm, which represents a pure green light emission with high intensity, thereby increasing the possibility of clearly distinguishing the luminous labels (markers).

As a result of the X-ray crystallographic analysis of the product, the absence of 1,10-phenanthrolone in the structure of the external sphere cation is clearly shown.

Also, structural differences between the known materials and the individual were ascertained as follows: (1) only one molecule of acetylacetone was present in the product; (2) two molecules of 1,10-phenanthrolone occupy the core metal; (3) Water molecules are present.

Changes in the composition and structure of the product will represent a substantial improvement in luminescent properties.

According to the component analysis, the X-ray analysis and the luminescence property analysis, the composition of the product was [Tb _0.5 Eb _0.5 (NO ₃ ) ₂ Acac (Phen) ₂ ] * H ₂ O (where Acac is an acetylacetonate ion And Phen represents 1,10-phenanthroline).

Examples 2-7

Except that the molar ratio of Tb (NO) ₃ * 6H ₂ O and Er (NO) ₃ * 6H ₂ O in Example 1 was changed so that the molar ratio of Tb and Er was as shown in Table 1 below. The same procedure was followed to prepare a lanthanide complex.

Comparative Example 1

[Tb (NO ₃ ) ₂ Acac (Phen) ₂ ] * H ₂ O in which only terbium was present as a center metal was regarded as Comparative Example 1.

Comparative Example 2

[Er (NO ₃ ) ₂ Acac (Phen) ₂ ] * H ₂ O in which only erbium was present as a center metal was regarded as Comparative Example 1.

Comparative Example 3

(PhenH) [Tb (NO ₃ ) ₂ AA ₂ Phen], which is a prototype compound, was used as Comparative Example 3.

Experimental Example 1

The luminescence (I _lum ), the heat emission (S) and the X-ray emission (R) characteristics of the lanthanum complexes of Examples 1 to 7 and Comparative Examples 1 to 3 were measured and described in Table 1 below. As can be seen from Table 1, the lanthanum-based complex of Example 7 exhibited the best luminescence characteristics, and in the case of Comparative Example 1, the luminescence characteristics were about 2 to 6 times that of Examples 1 to 7 Respectively.

<Table 1>

division Furtherance I _lum ,% S,% R, Example 1 _{[Tb 0.5 Er 0.5 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 10 85 15 Example 2 _{[Tb 0.6 Er 0.4 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 10 73 15 Example 3 _{[Tb 0.7 Er 0.3 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 30 122 40 Example 4 _{[Tb 0.8 Er 0.2 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 50 163 60 Example 5 _{[Tb 0.9 Er 0.1 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 90 189 95 Example 6 _{[Tb 0.95 Er 0.05 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 95 239 100 Example 7 _{[Tb 0.99 Er 0.01 (NO 3} ) 2 Acac (Phen) 2] * H 2 O 100 206 100 Comparative Example 1 [Tb (NO ₃ ) ₂ Acac (Phen) ₂ ] * H ₂ O 100 100 100 Comparative Example 2 [ErNO ₃ ) ₂ Acac (Phen) ₂ ] * H ₂ O - - - Comparative Example 3 _{(PhenH) [Tb (NO 3} ) 2 Acac 2 Phen] * H 2 O 80 40 80

Example 10

The lanthanide complexes prepared in Examples 1 to 7 were dissolved in acetone to prepare an invisible light-emitting ink.

Experimental Example 1

The ink prepared in Example 10 was coated on the polymer surface or paper surface in the form of a label and dried. Ultraviolet rays and X-rays were irradiated to the surface on which the label was described to cause luminescence of green (maximum wavelength = 545 nm).

Further, in order to measure the heat emission, ultraviolet rays or X-rays were irradiated to the surface on which the label was described at low temperature, and then the cold surface was heated to measure the heat-luminescence characteristics. Also, the verification of the label was carried out so that the contents were clearly identified.

The application of the ink was checked on various polymeric carriers such as polymethyl methacrylate (PMMA), polystyrene (PS), and polyvinyl butyral (PVB).

The most excellent results were obtained for the polyvinyl butyral to which the non-visible light-emitting ink containing the lanthanide complex of Example 7 was applied, the strong ultraviolet light emission characteristic, the X-ray light emission property and the heat-emitting property were maintained, Lt; RTI ID = 0.0 &gt; photo-chemically &lt; / RTI &gt;

The relative luminescence characteristics to the concentration of the lanthanum complex and the duration for polyvinyl butyral are shown in Table 2 below.

<Table 2>

0.0062
0.0121
0.0181
0.0238
0.0301 1.0
3.92
4.83
9.98
19.14 1.00
2.73
4.26
9.68
19.14

As can be seen from the results in Table 2, the luminescent intensity of the lanthanide complex of Example 7 increased linearly with the increase of the concentration of the complex. During a period of 3 months, the emission intensity was unchanged and the heat-luminescent properties were maintained.

Claims (8)

delete delete A lanthanide complex represented by the following formula (3) (3)

In the formula, Ln represents Tb _a Er _1-a , and _a represents a number of 0.7 to 0.9. delete A non-visible light-emitting ink comprising a lanthanide complex according to claim 3 or 4. 6. The method of claim 5, &Lt; / RTI &gt; further comprising a solvent. 6. The method of claim 5, Wherein the content of said lanthanide complex is from 0.001 to 1% by weight based on the total ink weight. 6. The method of claim 5, Wherein the content of said lanthanide complex is from 0.001 to 0.05% by weight based on the total ink weight.