m-PEG7-azide

m-PEG7-azide is a polyethylene glycol (PEG)-based azide linker designed for modular assembly of PROTACs and other targeted conjugates. Its PEG spacer provides conformational flexibility and improved solubility, while the terminal azide enables efficient bioorthogonal coupling to complementary handles. This combination supports reliable linker installation and subsequent formation of well-defined ternary-recruiting architectures. The structure and reactivity of this linker are described in detail below.

Structure: The linker comprises a PEG chain terminating in an azide functional group, featuring ether linkages along the polyether backbone and a terminal N3 moiety. The flexible, hydrophilic PEG segment promotes favorable dispersion in aqueous media and helps reduce steric constraints during conjugation and target engagement.

Reactivity: The azide is well suited for copper-free or copper-catalyzed azide–alkyne cycloaddition with an appropriate alkyne partner to form a stable triazole linkage. Typical conjugation workflows use compatible polar solvents and mild conditions to preserve sensitive ligands, with reaction progress monitored by standard analytical methods. The mechanism relies on selective cycloaddition between the azide and terminal alkyne under bioorthogonal conditions.