– Ald-Ph-PEG4-bis-PEG4-propargyl, an 8-unit PEG ADC linker, plays a pivotal role in the production of antibody-drug conjugates (ADCs) [1]. This compound serves as a click chemistry reagent, featuring an Alkyne group that enables it to participate in copper-catalyzed azide-alkyne cycloaddition (CuAAc) with Azide-containing molecules.