Near-ir light-cleavable conjugates and conjugate precursors

A conjugate having a chemical structure according to Formula I, or a pharmaceutically acceptable salt thereof:

• wherein m is 1, 2, 3, 4, or 5;
• each n independently is 1, 2, or 3;
• R1 and R4 independently are alkyl, haloalkyl, cycloalkyl, alkoxy, —ROH, —RC(O)OH, —C(O)—R, or —C(O)—O—R, wherein R is alkyl;
• R2 is C(Re)2 wherein each RC independently is H, halo, alkyl, or aryl, or (R2)m collectively is phenyl;
• R3 is -L1-C(O)—X2-drug, where L1 is absent or a linker moiety and X2 is O, N(H), or N(CH3);
• R5 is —(CH2)x-L2-Ra, where x is an integer≥1, L2 is a linker moiety or is absent, and Ra is —C(O)N(H)Rb, —N(H)C(O)Rb, —N(H)Rb, —SRb,
• where y is an integer≥1 and Rb is a targeting agent,
• X1 is O, N, or CH2;
• G1 is
• G2 is
• R6 and R7 independently are alkyl sulfonate, H, alkyl, alkoxy, or substituted aminoalkyl;
• R8-R19 independently are H, alkyl, amino, alkoxy, or alkyl sulfonate;
• each Y independently is C(Rd)2, S, O, Se, or N(Rd) wherein each Rd independently is alkyl or H;
• and
• each ring A independently is a 6-membered fused aryl, aliphatic, heteroaliphatic, or heteroaryl ring.