Phthalamide-PEG3-azide is widely used in bioconjugation and click chemistry applications due to its azide functional group, which allows for efficient and selective reactions with alkyne-containing molecules. It serves as a linker in the development of antibody-drug conjugates (ADCs), enabling the attachment of therapeutic agents to antibodies for targeted cancer therapy. Additionally, it is employed in the modification of biomolecules, such as proteins and peptides, to enhance their stability, solubility, or functionality. Its PEG spacer improves water solubility and reduces immunogenicity, making it valuable in drug delivery systems and biomedical research. This compound is also utilized in materials science for surface functionalization and the creation of bioactive coatings.