Rare earth metal complexes that excite in the long UV wavelength range

1. A rare earth metal complex represented by the formula (I):

wherein:

M is a cation;

RE is a rare earth metal;

X is a counter anion;

R 1 , R 2 , R 3 , and R 4 are each independently selected from the group consisting of hydrogen, alkyl of 1-8 carbon atoms, aryl, halo, and alkoxy; and

said complex fluoresces when irradiated with UV light having a wavelength between 350 nm and 390 nm.

2. The rare earth metal complex according to claim 1 , wherein said cation is an alkali metal selected from the group consisting of sodium, potassium, and mixtures thereof.

3. The rare earth metal complex according to claim 1 , wherein said rare earth metal is selected from the group consisting of Europium (Eu), Gadolinium (Gd), Terbium (Tb), and mixtures thereof.

4. The rare earth metal complex according to claim 1 , wherein said counter anion is a halide.

5. The rare earth metal complex according to claim 1 , wherein each of said R 1 , R 2 , R 3 , and R 4 is hydrogen.

6. The rare earth metal complex according to claim 1 , wherein said rare earth complex is represented by the formula:

7. The rare earth metal complex according to claim 1 , wherein said rare earth complex has a solubility in water and/or water-ethanol mixtures of at least 1 wt %.

8. A process for preparing rare earth metal complexes of formula

wherein:

M is a cation;

RE is a rare earth metal;

X is a counter anion; and

R 1 , R 2 , R 3 , and R 4 are each independently selected from the group consisting of hydrogen, alkyl of 1-8 carbon atoms, aryl, halo, and alkoxy; and

said complex fluoresces when irradiated with UV light having a wavelength between 350 nm and 390 nm;

wherein said process comprises the step of contacting:

(i) a trialkali salt of a 5,6-diaryl-3-(2-pyridyl)-1,2,4-triazine trisulfonic acid derivative represented by formula (II):

wherein:

M is a cation; and

R 1 , R 2 , R 3 , and R 4 are each independently selected from the group consisting of hydrogen, alkyl of 1-8 carbon atoms, aryl, halo, and alkoxy; and

(ii) a rare earth metal salt represented by the formula:

RE 3+ X − 3

wherein:

RE is a rare earth metal; and

X is a counter anion;

wherein said step of contacting reactants (i) and (ii) is carried out in the presence of a solvent, and at a temperature and length of time sufficient to produce said rare earth metal complex of formula (I) that fluoresces when irradiated with UV light having a wavelength between 350 nm and 390 nm.

9. The process of preparing rare earth metal complexes according to claim 8 , wherein said cation is selected from the group consisting of sodium, potassium, and mixtures thereof.

10. The process of preparing rare earth metal complexes according to claim 8 , wherein said counter anion is a halide.

11. The process of preparing rare earth metal complexes according to claim 8 , wherein said rare earth metal is selected from the group consisting of Eu, Gd, Tb, and mixtures thereof.

12. The process of preparing rare earth metal complexes according to claim 8 , wherein said R 1 , R 2 , R 3 , and R 4 are each hydrogen.

13. A composition comprising the rare earth metal complex of formula (I) according to claim 1 , wherein said composition is selected from the group consisting of ink, inkjet ink, fluorescent ink, colored paint, mass coloring polymer, coating, dispersion, and security marking.

14. A composition comprising:

at least one rare earth metal complex of formula (I) according to claim 1 ; and

at least one carrier,

wherein said carrier comprises a solvent.

15. The composition according to claim 14 , wherein said rare earth metal complex of formula (I) comprises about 0.001% to about 15.0% by weight of the total weight of the composition.

16. The composition according to claim 14 , wherein said carrier is an ink composition.

17. The composition according to claim 16 , wherein said ink composition is used in a printer selected from the group consisting of: inkjet printers, thermal printers, piezo printers, and laser printers.

18. A method of using the rare earth metal complex of formula (I) according to claim 1 , comprising printing said rare earth metal complex onto an article.

19. The method according to claim 18 , wherein said article is selected from the group consisting of currency, passports, chip cards, checks, check cards, credit cards, debit cards, identity cards, certificates, bank notes, and postal items.

20. A mark comprising the rare earth metal complex of formula (I) according to claim 1 , wherein said mark is soluble in water-based ink jet systems.

21. The mark according to claim 20 , wherein said rare earth metal complex is fluorine-free.

22. The mark according to claim 20 , wherein said rare earth metal complex comprises

a europium salt;

a 5,6-diphenyl-3-(2-pyridinyl)-1,2,4-triazine group; and

water.

23. The mark according to claim 22 , wherein said 5,6-diphenyl-3-(2-pyridinyl)-1,2,4-triazine group is 4,4′-[3-[4-(4-sulfophenyl)-2-pyridinyl]-1,2,4-triazine-5,6-diphenyl]-bis-benzenesulfonic acid, trisodium salt.

24. An article of commerce comprising the mark according to claim 20 , wherein at least one article of commerce is selected from the group consisting of currency, passports, chip cards, checks, check cards, credit cards, debit cards, identity cards, certificates, bank notes, and postal items.

25. A method for applying the mark according to claim 20 to an article of commerce comprising printing said mark on said article of commerce.

26. The method according to claim 25 , wherein said printing is by a printer, wherein said printers is at least one selected from the group consisting of inkjet printers, thermal printers, piezo printers, and laser printers.

27. An article comprising the rare earth metal complex of formula (I) according to claim 1 , wherein said article is selected from the group consisting of film, data carrier, paper, spun fiber, dyed fiber, biochemistry tracer, and display.