Clickable fluorescent dyes for multimodal bioorthogonal imaging

Bioorthogonal ligation with functionalized fluorescent dyes enables visualization of nuclei acids, proteins and metabolites in biological systems. Bright and modular azide- and alkyne-functionalized dyes are therefore needed to expand the fluorescence imaging capabilities of bioorthogonal ligation methods. We describe the concise synthesis of clickable fluorescent dyes based on 2-dicyanomethylene-3-cyano-2,5-dihydrofuran fluorophores and demonstrate their utility for multicolor imaging of azide- and alkyne-modified proteins as well as FRET studies.