BCN-exo-PEG2-NH2 is an ADC Linker containing 2 PEG units. BCN-exo-PEG2-NH2 contains the lyophilic bidentate macrocyclic ligand BCN, which can further synthesize macrocyclic complexes. In click chemistry , BCN reacts with molecules containing azide groups to form stable triazoles in the absence of catalysts.