Fluorescent dyes, labeled conjugates and analytical methods

A dye compound represented by the formula (I)

• wherein
• D is selected from —C-(A)q-R6, and
• X is selected from oxygen, sulfur, selenium, and N—B,
• B is selected from hydrogen, alkyl having from 1 to 10 carbon atoms, aryl, heteroaryl, acyl, aroyl having from 1 to 10 carbon atoms and heteroaroyl having from 1 to 10 carbon atoms;
• Z is carbon;
• Za is selected from carbon and —C-(A)q-R6;
• Zb is selected from carbon, N-alkyl and N-aryl;
• A is a divalent linking group having alternating single and multiple bonds;
• Y is a proton transfer group selected from one or more of the compounds selected from the group consisting of OH, NH2, —NHSO2Ar, —NHSO2OH, —NHC(═O)OH, —O(PG), —N(PG)SO2Ar, —N(PG)SO2OH, —N(PG)C(═O)Ar and —N(PG)C(═O)OH wherein PG is a protective group;
• R1, R2 and R3 each independently is selected from hydrogen, an electron withdrawing group and an electron releasing group;
• or R1 and R2 taken together with the carbon atoms to which they are attached represent the carbon atoms necessary to form a substituted or unsubstituted unsaturated carbocyclic or heteroaromatic ring;
• R4 is selected from hydrogen, an electron withdrawing group and an electron releasing group;
• n is an integer of from 0 to 4;
• q is 0 or 1;
• R6 is
• wherein the line “-” drawn on the left side of the compound represents a bond to “C” in the compound —C-(A)q-R6 when q is 0 and a bond to “A” when q is 1;
• where R11 is H, alkyl, aryl, heteroaryl;
• R12 is hydrogen, alkyl, aryl or heteroaryl;
• and
• provided that when D is
• at least one of Za is —C-(A)q-R6.