Abstract
We developed a fast strain-promoted azide-alkyne cycloaddition reaction (SPAAC) by tetra-fluorinated aromatic azide with a kinetic constant of 3.60 M(-1) s(-1), which is among the fastest SPAAC ligations reported so far. We successfully employed the reaction for covalent labelling of proteins with high efficiency and for bioimaging of mitochondria in living cells. The reaction could be a generally useful toolbox for chemical biology and biomaterials.