substituted or unsubstituted vinylpyrrolidone an optionally polymerized substituted or unsubstituted oxirane an optionally polymerized substituted or unsubstituted oxetane an optionally polymerized substituted or unsubstituted oxolane an optionally polymerized substituted or unsubstituted episulfide an optionally polymerized substituted or unsubstituted thiotane and an optionally polymerized substituted or unsubstituted cyclic amine with the proviso that r 1 to r 6 are not all identical linear alkyls when y is nr 5 r 6 and z is o and that r 1 and r 2 are not both ethyl when nr 3 r 4 and nr 5 r 6 both constitute a morpholinyl ring in a preferred embodiment of the fluorescent dye compound of the invention x 1 x 3 x 5 x 7 x 9 and x 11 are all h in another preferred embodiment x 1 x 3 x 5 x 7 x 9 and x 11 are all cl in a yet other embodiment x 1 x 3 x 5 x 7 x 9 and x 11 are all f in a further preferred embodiment y is selected from h cl and f thus in a preferred embodiment y is h in another preferred embodiment y is cl and in a yet other preferred embodiment y is f in a highly preferred embodiment x is one of the above described and y is one of the above described in a further preferred embodiment of the fluorescent dye compound of the invention y is f and z is o or nr 10 thus in one preferred embodiment y is f and z is o and in another preferred embodiment y is f and z is nr 10 in further preferred embodiment y is selected from the group.