Supramolecular chemosensor for selective detection of iron in aqueous medium

We have successfully developed a turn-on' colorimetric chemosensor for Fe3+ based on 1,10-phenanthroline. An amide derivative of 1,10-phenanthroline 4 was developed for the selective recognition of Fe3+ over Co2+, Cr3+, Cu2+, Mn2+, Ni2+, Ag+ and Zn2+ and could measure Fe3+ concentration in the range of 15-210M by UV-vis spectroscopy. Moreover, the addition of Fe3+ to a colourless solution of 4 turned its colour to light pink, indicating that 4 is capable of detecting Fe3+ by the naked eye. Compound 4 exhibits a major absorption band centred at 268 which shifted to 278nm after addition of Fe3+, and a shoulder band around 514nm was also observed. The complexation of Fe3+ with 4 was analysed at a different pH and favourable binding was observed at pH 6.2.