Functional helquats: helical cationic dyes with marked, switchable chiroptical properties in the visible region

Abstract

Helquat dyes are the first helicene-like cationic styryl dyes obtained as separate enantiomers. Their remarkable chiroptical properties are due to the unique combination of a cationic hemicyanine chromophore and a helicene-like motif.

The magnitude of the ECD response and the pH switching along with their positioning in the visible region are unprecedented among helicenoids.

Keywords

• helical cationic dyes
• pH-switch
• chiroptical properties
• circular-dichroism
• enantioselective synthesis
• trogers base
• end-groups