A highly selective, sensitive and “turn-on” fluorescent sensor for the paramagnetic Fe3+ ion

A highly selective and sensitive chemosensor for Fe3+ ion using 2-((4-methylbenzo-[d]thiazole-2-ylimino)methyl)phenol is developed. The probe 1 is found to be more selective towards Fe3+ over other metal ions such as Li+, Na+, K+, Ca2+, Mn2+, Cr3+,Co2+, Ni2+, Cu2+, Hg2+, Pb2+, Cd2+, Al3+, Zn2+, Ru3+and Ag+ with a limit of detection 0.89 nM. Upon binding to Fe3+ ion, a strong fluorescent enhancement is observed which is attributed to an increase in Charge Transfer. A 1:1 binding between probe 1 and Fe3+ ion is evidenced by Job’s plot. The proposed mechanism is strongly supported by TD-DFT calculations.