Electrochromic and electrofluorochromic properties of a new boron dipyrromethene–ferrocene conjugate

► New boron dipyrromethene–ferrocene conjugate exhibiting electrochromic properties. ► Four redox states are available and investigated by spectroelectrochemistry. ► The fluorescence can be switched on by chemical or electrochemical oxidation. ► Fluorescence can be monitored reversibly under electrochemical control. A new boron dipyrromethene–ferrocene (BODIPY–Fc) conjugate with pentafluorophenyl as the meso substituent and two Fc termini was synthesized and its spectroscopic and electrochemical features were analyzed. An intramolecular charge transfer from the donor Fc to the acceptor BODIPY has been predicted by theory and confirmed experimentally, leading to efficient fluorescence quenching when the dyad is in the neutral state. Fluorescence can be triggered by oxidizing both ferrocenyl units either chemically or electrochemically. Eventually, a fully reversible fluorescence switch is evidenced by coupling TIRF microscopy with electrolysis in an electrochemical cell.