Used in bioorthogonal chemistry for labeling and imaging applications, particularly in live-cell imaging and tracking. Its tetrazine group enables rapid and selective reactions with trans-cyclooctene (TCO) or other dienophiles, making it valuable for click chemistry. The PEG4 spacer enhances solubility and reduces steric hindrance, improving reactivity in biological systems. The azide group allows further conjugation via click chemistry, such as with alkynes, expanding its utility in bioconjugation and drug delivery. Commonly employed in the development of targeted therapeutics, diagnostics, and molecular probes.