This is the hydrobromide salt of the tri-tert-butyl ester derivative of 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (H₃Do3A), a key synthetic intermediate in coordination chemistry and radiopharmaceuticals. The tert-butyl protecting groups enable selective functionalization and conjugation prior to deprotection. Upon hydrolysis of the esters, the resulting ligand forms highly stable complexes with metal ions, especially lanthanides and actinides. These properties make it essential for developing MRI contrast agents, targeted drug delivery systems where metal-binding facilitates attachment of therapeutics to specific cells or tissues, and radiotracers for diagnostic imaging and cancer therapy. Its macrocyclic structure provides exceptional thermodynamic stability and kinetic inertness in biological environments.