Novel fluorescent chemosensors based on carbazole for Cu2+ and Fe3+ in aqueous media

We have developed carbazole-based fluorescent chemosensors that exhibit fluorescence quenching upon binding Cu2+ and Fe3+ in the Tris–HCl (0.01 M DMSO/H2O (v/v) 1:1, buffer, pH=7.4) solution system by fluorescence titration experiments at 25 °C. These sensors form a 1:1 complex with Cu2+ or Fe3+ and show a fluorescent quenching based on photoinduced electron transfer (PET) with a binding constant of (3.44±0.05)×103 and (1.50±0.06)×104, respectively. All the chemosensors (1–4) show the highest sensitivity for Cu2+ and Fe3+ over other metal cations in aqueous solution.