Aromatic fluorine atom-induced highly amine-sensitive trimethine cyanine dye showing colorimetric and ratiometric fluorescence change.

Herein, introducing multiple fluorine atoms into aromatic rings of trimethine cyanine dyes is proposed as a powerful method for dramatically increasing sensitivity to amines. The highly sensitive ratiometric fluorescence properties previously available only by intramolecular addition can be exploited in reactions with intermolecular amines or other nucleophiles.