Used as an activating agent in peptide synthesis, facilitating the coupling of amino acids by enhancing the reactivity of carboxyl groups. It is particularly effective in solid-phase peptide synthesis due to its stability and efficiency in forming amide bonds. Also employed in the preparation of active esters for bioconjugation reactions, enabling labeling of proteins and other biomolecules. Its electron-withdrawing nitro group improves leaving group ability, making it valuable in mild, selective acylation processes.