Synthesis of Zwitterionic Water-Soluble Oligofluorenes with Good Light-Harvesting Ability

A new water‐soluble zwitterionic oligofluorene bearing carboxylic acid and quaternary ammonium as pendant groups (OF‐1) is synthesized and characterized. It forms aggregates by intermolecular electrostatic interactions and exhibits similar light‐harvesting ability as that of conjugated polymers. Efficient fluorescence resonance energy transfer (FRET) occurs from OF‐1 to double‐stranded DNA tagged with fluorescein (dsDNA‐F1). A photoresponsive oligofluorene (OF‐3) is also synthesized by protecting OF‐1 with 1‐(2‐nitrophenyl)ethanol. Photolysis of OF‐3 can produce OF‐1 to result in a fluorescence “turn‐on” response, thus the FRET from OF‐3 to dsDNA‐Fl can be turned on by light irradiation. OF‐3 offers the potential for remote DNA sensing. A new water‐soluble zwitterionic oligofluorene bearing carboxylic acid and quaternary ammonium as pendant groups (OF‐1) is synthesized and characterized. It forms aggregates by intermolecular electrostatic interactions and exhibits similar light‐harvesting ability as those of conjugated polymers. Efficient fluorescence resonance energy transfer occurs from OF‐1 to double‐stranded DNA tagged with fluorescein. A remote DNA sensing is also developed.