Patent ID: 7717964

Claim:
A fluorescent dye of formula (I): the organic or mineral acid salts thereof, optical isomers and geometric isomers thereof, or the solvates thereof: wherein in formula (I): R 1 is chosen from a C 1 -C 6 alkyl group substituted with at least one hydroxyl group or —C(O)OR′ group, wherein R′ is chosen from a hydrogen atom, a C 1 -C 4 alkyl group, or a —C(O)—O − group, wherein when R′ is a —C(O)—O − group an anionic counterion An − is absent; R 2 is chosen from a C 1 -C 6 alkyl group optionally substituted with at least one hydroxyl group; or else the groups R 1 and R 2 form, together with the nitrogen which bears them, a saturated heterocyclic radical substituted at least with a hydroxyl, (poly)hydroxy(C 1 -C 4 )alkyl, and/or —C(O)OR′ group, with R′ chosen from a hydrogen atom, a C 1 -C 4 alkyl group or a —C(O)—O − group, wherein when R′ is a —C(O)—O − group an anionic counterion An − is absent; R 3 is chosen from a hydrogen atom or a —C(O)OR″ group, with R″ chosen from a hydrogen atom, an alkali metal or a C 1 -C 6 alkyl group, or else R 3 is chosen from a —C(O)—O − group and, in this case, an anionic counterion An − is absent; Z is chosen from a divalent amido —C(O)—N(R)— or —N(R)—C(O)— group, or a divalent C 1 -C 10 alkylene group interrupted with an amido —C(O)—N(R)— or —N(R)—C(O)— group wherein R is chosen from a hydrogen atom or a C 1 -C 6 alkyl group; n is an integer ranging from 1 to 2; m is an integer ranging from 0 to 1; An − represents an anionic counterion; Y is chosen from: i) a hydrogen atom, ii) an alkali metal, iii) an alkaline earth metal, iv) an ammonium group: N + R α R β R γ R δ , a phosphonium group: P + R α R β R γ R δ with R α , R β , R γ and R δ , which may be identical or different, are chosen from a hydrogen atom or a (C 1 -C 4 )alkyl group, or v) a thiol-function-protecting group; wherein: the bond between the pyridinium ring and the double bond of the styryl group is positioned in the 2- or 4-position with respect to the pyridinium; when n=1, m=1, then Y=H or a thiol-function-protecting group and when n=2, then m=0; when the compound of formula (I) comprises other cationic parts, it is associated with one or more anionic counterions which allow formula (I) to achieve electroneutrality.