Fluorescent maleimides and uses thereof

Details Fluorescent maleimides and uses thereof Fluorescent maleimides and uses thereof

2000-08-22

2001-07-10

McKane, Joseph K. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C546S256000, C548S524000, C548S526000, C548S444000, C548S549000

Reexamination Certificate

active

06258954

ABSTRACT:

The present invention relates to fluorescent maleimides of the formula I
wherein
R
1
and R
2
independently from each other stand for
wherein Q
1
stands for hydrogen, halogen, phenyl, —E—C
1
-C
8
alkyl, —E-phenyl, wherein phenyl can be substituted up to three times with C
1
-C
8
alkyl, halogen, C
1
-C
8
alkoxy, diphenylamino, —CH═CH—Q
2
, wherein Q
2
stands for phenyl, pyridyl, or thiophenyl, which can be substituted up to three times with C
1
-C
8
alkyl, halogen, C
1
-C
8
alkoxy, —CN, wherein E stands for oxygen or sulfur, and wherein R
21
stands for C
1
-C
8
alkyl, phenyl, which can be substituted up to three times with C
1
-C
4
alkyl, C
1
-C
4
alkoxy, or dimethylamino, and R
22
and R
23
independently from each other stand for hydrogen, R
21
, C
1
-C
8
alkoxy, or dimethylamino,
or —NR
4
R
5
, wherein R
4
and R
5
, independently from each other stand for hydrogen, phenyl, or C
1
-C
8
alkyl-carbonyl, or —NR
4
R
5
stands for a five- or six-membered ring system, and R
3
stands for allyl,
wherein Q
3
stands for hydrogen, halogen, C
1
-C
8
alkoxy, C
1
-C
8
alkyl-amido, unsubstituted or substituted C
1
-C
8
alkyl, unsubstituted or up to three times with halogen, —NH
2
, —OH, or C
1
-C
8
alkyl substituted phenyl,
and Z stands for a di- or trivalent radical selected from the group consisting of substituted or unsubstituted cyclohexylene, preferably 1,4-cyclohexylene, triazin-2,4,6-triyl, C
1
-C
6
alkylene, 1,5-naphthylene,
 wherein
Z
1
, Z
2
and Z
3
, independently from each other stand for cyclohexylene or up to three times with C
1
-C
4
alkyl substituted or unsubstituted phenylene, preferably unsubstituted or substituted 1,4-phenylene,
and wherein R
6
and R
7
, independently from each other, stand for
n stands for 1, 2 or 3, and m stands for 1 or 2, with the proviso, that R
1
and R
2
not simultaneously stand for phenyl,
and its different uses such as in electroluminescent devices and as void detection compounds.
Compounds which are both, fluorescent and photostabile, are rare. This is mainly because fluorescence and photostability are usually incompatible with each other. The majority of fluorescent materials obtained to date are compositions employing fluorescent dyes, showing advantages of strong fluorescence, however, at the same time poor lightfastness, too. Hence, the known fluorescent materials are applied for only limited applications, e.g. interior uses, i.e. almost no uses are known for applications where high lightfastness is required.
In particular, perylene based compounds (especially compounds of the known LUMOGEN® series from BASF) for highly photostabile and fluorescent compounds are used by dissolving it into media such as plastics to give fluorescent compositions. However, their solubility is insufficient thereby failing in obtaining strong color strength of the corresponding compositions.
Further, EP-A 456,609 discloses the preparation and use of a benzoimidazoisoindolone as a highly photostabile and fluorescent pigment. However, this pigment exhibits only a weak solid-state fluorescence and a weak reflection color. In addition, the obtained color range is limited to only greenish yellow to yellow. Another disadvantage is that a kind of benzoimidazoisoindolone irritates the skin and crystal growth is too fast in a polymer matrix.
Also used are coumarin and rhodamine dyes dispersed in a plastic matrix (so-called fluorescent pigments). However, their photostability is poor.
Some maleimide derivatives are well-known compounds. E.g. J.Org.Chem. 42 (1977) 2819-2825 describes 1,2-diphenylmaleyl derivatives such as 1,2-diphenylmaleyl-N-cyclohexylimide as a protecting group for amino functions. Although it is mentioned that these compounds are yellow and fluorescent, no examples and no evaluation is given with regard to fluorescence properties and photostabilities.
Tetrahedron 51 (1995) 9941-9946 describe the synthesis of the marine alkaloid polycitrin, another red, fluorescent 1,2-diphenylmaleyl derivative, and intermediates thereof. However, the object of this work is not to show ways to enhance fluorescent properties and photostability of maleimide derivatives.
U.S. Pat. No. 4,596,867 describes the preparation of disubstituted maleic anhydride compounds. On col. 5 it is speculated that the imides of this compounds with amines such as t-butylaniline or octadecylamine can yield soluble compounds useful as fluorescent dyes and markers. However, no examples or other hints are given to support this statement. Rather, examples are directed to the preparation of polyimides in which the claimed anhydrides are reacted with diamines. In addition, there is no teaching of how to increase the photostability of fluorescent maleimide compounds.
Chem. Pharm. Bull. 28(7) (1980) 2178-2184 describes, too, diphenylmaleimides of the formula
wherein R
8
stands for —CH
2
Ph, —CH
2
CH
2
CH
3
, —CH(CH
3
)
2
, and —CH
2
CH(CH
3
)
2
. Although the compounds are described as yellow fluorescent compounds nothing is mentioned concerning increasing the properties of photostability and fluorescence.
JP-A2 50123664 describes a method for the preparation of
wherein R stands for C
1
-C
4
alkyl, phenyl or tolyl, and Ar stands for phenyl or tolyl. Explicitly, two compounds are prepared wherein Ar stands for phenyl, and R for n-butyl and phenyl, resp. However, nothing is mentioned about fluorescence and photostability. Rather, it is speculated that this compounds are usable as medical drugs, pesticides and starting materials thereof.
Chem. Ber. 26 (1893) 2479 describes the preparation of 3,4,3′,4′-tetraphenyl-1,1′ethandiyl-bis-pyrrole-2,5-dione. However, nothing is known with regard to photostability, fluorescence, and its uses inter alia in electroluminescent devices.
EP-A 628,588 describes the use of bismaleimides, especially
to increase the molecular weight of polyamides. However, no teaching is given with regard to the photostability and fluorescence of the mentioned compounds and other uses.
Hence, the object of the present invention was to provide photostabile fluorescent compounds, preferably exhibiting a high photostability and a strong solid-state and/or molecular state fluorescence. Further, another object is to broaden the range of available colors within this field, preferably strong reflection colors, combined with the abovementioned properties.
In addition, the provided compounds should be usable in electroluminescent devices as light-emitting substances, as void detection compounds, as inks for security printings, emitters for scintilators, light absorbers for solar collectors, light converters for agriculture etc.
Especially, fluorescent compounds should be provided which, compared to optical brighteners, have a superior solubility thus making an incorporation into paints and lacquers more easy. In addition, the fluorescent compounds should show fluorescence in the solid state, a superior photostability with no or only minimal products leading to discoloration of e.g. white coatings, a lesser migration, a lesser contamination of the working environment, fluorescence should be observed only at voids and not at the whole surface yielding a better contrast compared to e.g. optical brighteners and allowing the detection of minor defects or damages. Further, the fluorescent compounds should be useful in dark and white pigmented systems in which optical brighteners fail. Finally, fluorescent compounds with a superior photostability should be provided allowing long-term void detection, i.e. an inspection after months or maybe years after the application.
Accordingly, the aforementioned fluorescent maleimides were found. In addition, novel compounds, their preparation and uses of the provided compounds such as in electroluminescent devices and as void detection compounds were found, too.
A preferred embodiment of the present invention relates to fluorescent maleimides of the formula II
wherein R
9
has the meaning of R
1
, and R
10
stands for R
3
.
Another preferred embodiment of the present invention relates to fluorescent maleimides of the for

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