Compositions – Organic luminescent material containing compositions
Reexamination Certificate
1998-02-03
2001-08-14
Koslow, C. Melissa (Department: 1755)
Compositions
Organic luminescent material containing compositions
C106S494000, C106S495000, C106S496000, C106S497000, C106S498000, C252S301210, C252S301220, C252S301230, C252S301240, C252S301170, C252S301260, C252S301270, C252S301280, C252S301290, C252S301310, C252S301320, C252S301340, C252S301350
Reexamination Certificate
active
06274065
ABSTRACT:
The invention relates to a process for the preparation of a solid fluorescent composition comprising
(1) mixing a host chromophore and an effective amount of a pigment precursor in a solvent, then generating a pigment as guest chromophore in-situ from the pigment precursor, and, subsequently, isolating the mixture of the host and guest chromophores, thereby forming a solid solution, or
(2) mixing a polymer as a matrix or a polymer precursor and a pigment precursor in a solvent, if desired in the presence of a chromophore being a host component, then generating a pigment in-situ from the pigment precursor (being the guest component if a host component is present), and, subsequently, isolating the mixture of polymer and pigment, and—if present—the host component, thereby forming a solid solution, wherein in all cases where there is a host component, the absorption spectrum of the pigment (guest chromophore) overlaps with the fluorescence emission spectrum of the host chromophore.
In addition, the present invention relates to a composition comprising a polymer matrix or a polymer precursor, and/or a host chromophore, and a pigment precursor or a pigment, wherein in all cases where there is a host component, the absorption spectrum of the pigment (as guest chromophore), obtainable from the pigment precursor, overlaps with the fluorescence emission spectrum of the host chromophore, a process for the preparation of a powder, a powder, a process for the preparation of a layer on a solid support material and the use of the abovementioned compositions and the powder as fluorescent materials.
Combinations consisting of host chromophores and guest chromophores dissolved in the host matrix to generate an enhanced fluorescence and a Stoke shift of the emission fluorescence through an energy transfer from the host to the guest are highly desired materials in many technical applications.
The possibility of energy transfer between chromophores that possess overlapping emission and excitation wavelengths of host and guest chromophores is known. For example, H. Port et al. describe in Z. Naturforsch., 36a, pages 697 to 704 (1981) mixed crystals of fluorene doped with dibenzofurane (or benzindan) which possess an enhanced fluorescence in the UV region, at temperatures below 100K. Although low temperature fluorescence has no practical value and is only of scientific interest.
C. W. Tang et al. disclose in J. Appl. Phys., 65, 3610 to 3616 (1989) a multilayer electroluminescent device with a light emitting layer composed of 8-hydroxyquinoline aluminum, in which is embedded a zone doped with a fluorescent molecule e.g. coumarin. The device shows improved electroluminescence and a large gap between the excitation and emission wavelengths. This Stoke's shift is dependent on the dopant employed. The manufacture of the device is complicated and not suitable for an industrial production.
J. M. Lang et al. describe in J. Phys. Chem. 97, pages 5058 to 5064 (1993) the combination of coumarin as host and rhodamine as guest whereby both components are dissolved in polyacrylic acid, but enhanced fluorescence is possible only under high pressure.
In WO 93/23492 are disclosed fluorescent microparticles with an enhanced Stokes shift, which are composed of soluble and fluorescent host and guest dyes absorbed or bonded to polymeric microparticles. The material is used for the optical detection of nucleic acids like DNA or RNA. Unfavorably, the solid state fluorescence of these microparticles is poor.
U.S. Pat. No. 5,227,252 discloses a fluorescent composition comprising a support material which is coated on one side with a layer of 8-hydroxyquinoline aluminum, as host, and a derivative of quinacridone, as guest. Similarly, JP-A-05 320 633 discloses a fluorescent composition comprising a support material which is coated on one side with a layer of 8-hydroxyquinoline aluminum, as host, and a diketopyrrolopyrrole, as guest. Although the guest structures are inherently insoluble materials, they are in fact dissolved mainly as microsized clusters, which is a consequence of the applied co-sublimation manufacturing process. The materials possess an enhanced Stoke shift fluorescence and are used for example as light emitting materials in electroluminescent devices. The sublimation temperatures of the used chromophores are quite different. The process for their manufacture, which is a co-sublimation of both components, placed in different containers, requires large expenditures of technical equipment for precise control of the different sublimation conditions like temperature to achieve uniform layers on the support. The process is not suitable for large scale industrial manufacture. The process is also not suitable for the production of powders, which are highly desired materials.
In EP-A-0 456 609 is disclosed a process for the preparation of 1,2,3,4-tetrachloro-benzo[4,5]imidazo[2,1-a]isoindol-11-one and its derivatives in the presence of selected solvents. They are pigments which display solid state fluorescence and improved outdoor durability. It is also mentioned therein, that the combination of 95% 1,2,3,4-tetrachloro-benzo[4,5]imidazo[2,1-a]isoindol-11-one with 5% of Indanthrone Blue generates a green fluorescent pigment. Such a system is a pigment composite, wherein the new color generated is simply a sum of the two component colors. The color is not created by virtue of the occurrence of complex, molecular level, energy transfer processes that require close interaction between the components of the mixture.
EP 0 654 711 A discloses a means for preparing structured color images via the use of a soluble pigment precursor, which can be subsequently transformed, by the use of chemical, thermal, photolytic or radiative means, to generate an insoluble, nanosize, stable pigment thereof. The composition is specific to the generation of aggregated pigment particles that are dispersed homogeneously throughout a polymer matrix. Thus the compositions show the color of the pigment and are not fluorescent.
Hence, the object of the invention on hand was to provide a fluorescent composition, which does not show the above-mentioned disadvantages, preferably a composition should be provided whereby
a highly uniform distribution of inherently insoluble pigment in a matrix of a host chromophore or in a polymer matrix is achieved;
a solid solution is achieved, wherein an insoluble pigment is dissolved, preferably in a molecularly state, and thus is distributed, preferably homogeneously, in a matrix of a host chromophore;
fluorescent materials are generated from polymers as matrix and contain a dissolved pigment;
fluorescent materials with enhanced luminescence are obtained by the co-use of a host chromophore and energy transfer from the host to the pigment even in a polymer matrix;
the manufacturing process is far less expensive than known processes, particularly compared with the known co-sublimation technique;
the space-time-yield is improved;
an economic industrial scale production is achieved;
even an easy preparation of fluorescent particles comprising a host chromophore matrix and a pigment is achieved;
fluorescent layers of a host chromophore matrix and a pigment directly are obtained from a powder from host chromophore/pigment mixtures;
fluorescent layers of a host chromophore matrix and a pigment directly are obtained from a powder from host chromophore/pigment precursor mixtures;
Further, enhancement factors for the present invention preferably should be all positive and should be at least 1.3, preferably at least 2 and more preferably at least 5. The term “enhancement factor” as used herein, is defined as the increased or decreased factor, in terms of peak height emission intensities of a solid-state composition comprising of host and guest fluorescent moieties compared to an identical polymer that does not contain fluorescent guest moieties. Comparisons are considered real, for as long as the excitation radiation wavelengths are identical. Naturally however the emission wavelen
Deno Takashi
Devlin Brian Gerrard
Iqbal Abul
Kodama Kunihiko
Ciba Specialty Chemicals Corporation
Crichton David R.
Koslow C. Melissa
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