Bridged fluorescent dyes, their preparation and their use in assays

A bridged fluorescent dye having the formula:

• wherein:
• RB2 is a bridge of from 8 to about 30 atoms in length attached at the R1 position;
• Z is O, S, Se, N, or —CR5R6;
• R1, R2, R3 and R4 are each independently, hydrogen, lower alkyl, substituted lower alkyl, water solubilizing group or adjacent pairs of Rs from an aromatic structure or cycloaliphatic structure with or without substitution, and wherein at least one of R1, R2, R3 and R4 is a water solubilizing group;
• R5 and R6 are each lower alkyls or together form a cycloalkyl;
• and
• R7 is independently alkyl or alkenyl substituent;
• and
• n1 is an integer from 3 to 1.

A bridged fluorescent dye having the formula:

• wherein RB1 is:
• wherein n2 is 1, 2, or 3;
• X is selected from the group consisting of O, S and Se, such that the dye has the formula:
• wherein RB2 is a bridge of from 8 to about 30 atoms in length each end of which is attached at the R1, N or Z positions;
• Z is O, S, Se, N, or —CR5R6;
• R1, R2, R3 and R4 are each independently, hydrogen, lower alkyl, substituted lower alkyl, water solubilizing group or adjacent pairs of Rs from an aromatic structure or cycloaliphatic structure with or without substitution, and wherein at least one of R1, R2, R3 and R4 is a water solubilizing group;
• R5 and R6 are each lower alkyls or together form a cycloalkyl;
• and
• R7 is independently alkyl or alkenyl substituent, or both R7 groups taken together are RB2.