Triphenylamine Derived Radical Cations for Colorimetric Cu²⁺ Sensors and as an Antibacterial Agent

Abstract

Herein, a series of triphenylamine derivatives (TPAs), which are comprised of electron donor and acceptor moieties, have been exploited as sensitive colorimetric sensors for Cu 2 + , operating via the formation of the corresponding organic radicals through a redox reaction in a mixed solvent system (acetonitrile/water). Further studies indicated that the Cu 2 + recognition triggered organic radical cations were stable in aqueous solution, and can be used as an antibacterial agent for both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at very low concentrations (10 À 7 M). On comparison with light irradiated photodynamic therapy triggered radicals, the present work reveals that the direct use of radical cations of TPAs is more convenient for practical applications in killing bacteria. This work thus provides new insight into the design of sensitive colorimetric sensors and antibacterial agents.