Design and synthesis of rhodamine based chemosensors for the detection of Fe3+ ions

The number and nature of coordinating entities as well as the size of chelating cavity in rhodamine based chemosensors were tuned to enhance the selectivity and sensitivity for Fe3+ ions. An intense pink color development and enhancement in fluorescence emission intensity of chemosensor 5 upon complex formation at pH 7·4 enabled the detection of Fe3+ ions in the presence of other competitive metal ions like Li+, Na+, K+, Cs+, Mg2+, Ca2+, Sr2+, Cr3+, Mn2+, Fe2+, Cu2+, Co2+, Ni2+, Zn2+, Cd2+, Hg2+, and Pb2+. A plausible application of chemosensor 5 in the imaging of live fibroblast cells exposed to Fe3+ ions is also demonstrated. ► Number and orientation of chelating atoms for detection of Fe3+ ions is explored. ► Probe 5 selectively detects Fe3+ even in the presence of competitive metal ions. ► Mechanistic aspects of Fe3+ selective sensing have been demonstrated. ► Distorted octahedral geometry of 5-Fe3+ complex is proposed. ► Imaging of live fibroblast cells exposed to Fe3+ ions is presented.