Diphenylterazine is primarily used in bioorthogonal chemistry, particularly in inverse electron-demand Diels-Alder (IEDDA) reactions. Its high reactivity with strained dienophiles such as trans-cyclooctene (TCO) makes it valuable for rapid and selective labeling of biomolecules in live cells and organisms. It is widely applied in fluorescence imaging, where it enables real-time tracking of proteins, nucleic acids, and cellular processes without interfering with native biochemical pathways. Due to its fast kinetics and stability under physiological conditions, diphenylterazine is also employed in pretargeted imaging strategies, including PET and SPECT, enhancing signal specificity and reducing background noise. Additionally, it plays a role in targeted drug delivery systems, where it facilitates the site-specific release of therapeutic agents through bioorthogonal activation.