Polymeric dyes with linker groups comprising deoxyribose

A compound having the following structure (Ia):

• or a stereoisomer, salt or tautomer thereof, wherein:
• M1 is, at each occurrence, independently a moiety comprising an active drug moiety;
• L1a is, at each occurrence, independently a heteroarylene linker;
• L1b, L2, and L3 are, at each occurrence, independently optional alkylene, alkenylene, alkynylene, heteroalkylene, heteroalkenylene or heteroalkynylene linkers;
• L4 is, at each occurrence, independently an alkylene, alkenylene, alkynylene, heteroalkylene, heteroalkenylene or heteroalkynylene linker;
• R1 and R2 are each independently H, OH, SH, alkyl, alkoxy, alkylether, heteroalkyl, —OP(═Ra)(Rb)Rc, Q, or L′;
• R4 is, at each occurrence, independently OH, SH, O−, S−, ORd or SRd;
• R5 is, at each occurrence, independently oxo, thioxo or absent;
• Ra is O or S;
• Rb is OH, SH, O−, S−, ORd or SRd;
• Rc is OH, SH, O−, S−, ORd, OL′, SRd, alkyl, alkoxy, heteroalkyl, heteroalkoxy, alkylether, alkoxyalkylether, phosphate, thiophosphate, phosphoalkyl, thiophosphoalkyl, phosphoalkylether or thiophosphoalkylether;
• Rd is a counter ion;
• Q is, at each occurrence, independently a moiety comprising a sulfhydryl, disulfide, activated ester, isothiocyanate, azide, alkyne, alkene, diene, dienophile, acid halide, sulfonyl halide, phosphine, α-haloamide, biotin, amino or maleimide functional group;
• L′is, at each occurrence, independently comprises an alkylene or heteroalkylene linker covalently bonded to:
• Q, a targeting moiety selected from an antibody and a cell surface receptor antagonist, an amino acid or polymer thereof, an enzyme, a receptor, a receptor ligand, a glycoprotein, an aptamer and a prion, an analyte molecule selected from a nucleic acid or polymer thereof, a solid support selected from a polymeric bead and a non-polymeric bead, or a nucleoside;
• m is, at each occurrence, an integer of one or greater;
• and
• n is an integer of one or greater.