TAMRA DBCO, 5-isomer is a derivative of tetramethylrhodamine (TMR, TAMRA) that includes a cyclooctyne moiety (dibenzocyclooctyne, DBCO). This compound is the pure 5-isomer and is capable of reacting rapidly and efficiently with azides in a copper-free manner through strain-promoted azide-alkyne cycloaddition (SPAAC). TAMRA DBCO, 5-isomer can be employed for labeling proteins, peptides, nucleic acids, and other azide-containing molecules.