A new fluorescence “turn-on” type chemosensor for Fe3+ based on naphthalimide and coumarin

• A new fluorescence chemosensor based on coumarin and naphthalimide was synthesized.
• The chemosensor exhibits high selectivity for Fe3+ with fluorescence-enhancement.
• The detection limit could reach 0.388 μM.

A new Fe3+-selective “turn-on” chemosensor 1 based on coumarin and naphthalimide was designed and synthesized. The chemosensor exhibits high selectivity for Fe3+ over other ions (Mn2+, Co2+, Ni2+, Cu2+, Ag+, Cd2+, Pb2+, Ca2+, Al3+, Ba2+, Hg2+, Li+, Mg2+, Sr2+, Zn2+ and K+) with fluorescence-enhancement in THF-H2O solution. The binding ratio of 1-Fe3+ complex was determined to be 1:1 according to the Job plot. The association constant Ka of Fe3+ binding with sensor 1 was (2.589 ± 0.206) × 103 M−1. The detection limit was calculated to be 0.388 μM.