Ultra bright dimeric or polymeric dyes

A compound having the following structure

• or a stereoisomer, salt or tautomer thereof, wherein:
• M is, at each occurrence, independently a fluorescent or colored moiety comprising three or more aryl or heteroaryl rings, or combinations thereof,
• L1, L2 and L3 are, at each occurrence, independently an optional alkylene, alkenylene, alkynylene, heteroalkylene, heteroalkenylene, heteroalkynylene or heteroatomic linker;
• L4 is, at each occurrence, independently an alkylene, alkenylene, alkynylene, heteroalkylene, heteroalkenylene or heteroalkynylene linker;
• R1 is, at each occurrence, independently H, alkyl or alkoxy;
• R2 and R3 are each independently H, OH, SH, alkyl, alkoxy, alkylether, —OP(═Ra)(Rb)Rc, Q, a linker comprising a covalent bond to Q, a linker comprising a covalent bond to an analyte molecule, a linker comprising a covalent bond to a solid support or a linker comprising a covalent bond to a further compound of structure (I), wherein:
• Ra is O or S;
• Rb is OH, SH, O, S, ORd or SRd;
• Rc is OH, SH, O, S, ORd, SRd, alkyl, alkoxy, alkylether, alkoxyalkylether, phosphate, thiophosphate, phosphoalkyl, thiophosphoalkyl, phosphoalkylether or thiophosphoalkylether;
• R4 is, at each occurrence, independently OH, SH, O, S, ORd or SRd;
• R5 is, at each occurrence, independently oxo, thioxo or absent;
• Q is, at each occurrence, independently a moiety comprising a reactive group capable of forming a covalent bond with an analyte molecule, a solid support or a complementary reactive group Q′;
• Rd is a cation;
• m is, at each occurrence, independently an integer of zero or greater, provided that at least one occurrence of m is an integer of three or greater;
• and
• n is an integer of one or greater.