Stock material or miscellaneous articles – Composite – Of inorganic material
Patent
1997-07-02
2000-06-06
Thibodeau, Paul
Stock material or miscellaneous articles
Composite
Of inorganic material
25230116, 25230135, 534 15, 546 6, 548106, B32B 900, C09K 1102, C07D23100
Patent
active
060716320
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to lanthanide.sup.III complexes of 1,3-diketones, which complexes have a high luminescence quantum yield as well as long-lasting luminescence, a narrowband emission spectrum and bright triboluminescence. The invention also relates to the use of said compounds for optical sensors sensitive to impact, tension or pressure.
The phenomenon of triboluminescence (emission of light under strong mechanical stress) has long been known and is described, inter alia, in Advances in Physics 1977, Vol. 26, No. 6, 887-948 or in Math. Naturwiss. Unterricht 45/4, 1992, 195-202. A great number of crystalline compounds display this phenomenon, but as yet only very few are known whose emission is so strong as to be easily observable also in daylight. The brightest triboluminescent substance known so far is triethylammonium tetrakis(dibenzoylmethanato)europate(III).
Although the phenomenon of triboluminescence is well known, its cause cannot be completely accounted for yet and hence no predictions can be made concerning the occurrence of particularly intense triboluminescent compounds.
Specific Eu(III) complexes with pyridine-N-oxide, 2-, 3-, or 4-picoline-N-oxide and bipyridine-N,N-dioxide as well as thenoyltrifluoroacetone as ligand are disclosed in CA 114(18):177114p as triboluminescent substances of intense brightness.
BRIEF SUMMARY OF THE INVENTION
It has now been found that a specific group of predominantly colourless lanthanide complexes displays particularly bright triboluminescence, which complexes have very narrowband emission lines, pronounced Stokes' shift, as well as long-lasting luminescence and a high quantum yield of photochemically excited luminenscence.
By virtue of their long-lasting photochemically excited luminescence and high luminescence quantum yield, these compounds are also particularly suitable for use as pigments or dyes in the field of security printing. Bank notes and securities are typical examples requiring a high degree of security against unauthorised duplication. The high luminescence of the compounds is able to induce colour changes in the documents printed therewith when duplicated in conventional manner, so that the documents are identifiable as duplicates.
DETAILED DESCRIPTION OF THE INVENTION
In one of its aspects, the invention relates to compounds of formula I ##STR2## M is Eu, Tb or Dy, Sm; R.sub.2 is hydrogen or C.sub.1 -C.sub.6 alkyl, and C.sub.1 -C.sub.6 alkyl, and p-methoxypyridine-N-oxide.
The C.sub.1 -C.sub.6 alkyl groups can be straight-chain or branched and are typically methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl or the different positional isomers of pentyl and hexyl. The alkyl groups preferably contain 3-5 carbon atoms.
M is preferably Eu, Tb or Dy.
R.sub.2 is preferably hydrogen.
Most preferably, R.sub.1 and R.sub.3 are each tert-butyl or phenyl.
The invention also relates to a process for the preparation of compounds of formula I, which comprises reacting compounds of formula II ##STR3## in an organic solvent with p-N,N-dimethylaminopyridine, N-methylimidazole or p-methoxy-pyridine-N-oxide, wherein R.sub.1, R.sub.2, R.sub.3 and M have the meaning given above.
The preparation of the compounds of formula II is known per se and is described in K. J. Eisentraut, R. E. Sievers, Inorg. Syn. 11, 1968, 94.
Organic solvents are preferably alcohols, ethers, ketones, acid amides, aliphatic or aromatic nitriles, saturated or unsaturated hydrocarbons, chlorinated hydrocarbons or aromatic compounds, or mixtures thereof.
Particularly preferred solvents are C.sub.1 -C.sub.6 alcohol, benzonitrile or acetonitrile.
The reaction is preferably carried out in the temperature range from 20.degree. C. to 150.degree. C.
Reaction time and printing conditions are per se non-critical, and the reaction is preferably carried out under conditions of normal pressure. The reaction time may be in the range from 10 minutes to 24 hours and is preferably from 1 to 5 hours.
By virtue of their luminescent propertie
REFERENCES:
patent: 3398099 (1968-08-01), Kleinerman
patent: 4761481 (1988-08-01), Hale et al.
patent: 4920195 (1990-04-01), Kankare et al.
patent: 5504195 (1996-04-01), Leedham et al.
patent: 5854008 (1998-12-01), Diamandis
Advances in Physics, 1977, vol. 26, No. 6, 887-948 "Triboluminescence" Allen Walton.
Inorganic Syntheses, 11, 1968, 94 "Volatile Rare-Earth Cholates of 2,2,6,6-Tetramethylheptane-3,5-dione" Kent Eisentraut.
Chemie--Ing.--Techn. 38, 3 (1966) 331-342 "Zerkleinerungsuntersuchungen mit tribolumineszierenden Stoffen" Kurten.
Ciba Specialty Chemicals Corporation
Crichton David R.
Kruer Kevin R.
Mansfield Kevin T.
Thibodeau Paul
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