Chelate-type Schiff base acting as a colorimetric sensor for iron in aqueous solution

•A new and highly selective colorimetric sensor for Fe2+ and Fe3+ was developed.•The receptor 1 could detect trace amounts of Fe3+ in real water samples.•The detection limit (0.19μM) of 1 for Fe3+ is much lower than that (5μM) recommended by WHO in drinking water. A new and simple colorimetric receptor 1, based on 2,3-dihydroxybenzaldehyde moiety and 2-(2-aminoethoxy)ethanamine moiety, has been synthesized and characterized. 1 showed a selective colorimetric sensing ability for iron ion by changing color from yellow to brown. The detection limit (0.19μM) of 1 for Fe3+ is far lower than WHO guideline (5μM) in the drinking water. Importantly, the chemosensor 1 could be used to detect and quantify Fe3+ in water samples.