Cy5-PEG2-exo-BCN, a Cyanine 5 (Cy5) dye derivative, incorporates two polyethylene glycol (PEG) units and features the hydrophilic bidentate macrocyclic ligand BCN. This compound is utilized in the synthesis of macrocyclic complexes and participates in click chemistry reactions with azide-bearing molecules to form stable triazoles without the need for catalysts.