A diaminomaleonitrile based selective colorimetric chemosensor for copper(ii) and fluoride ionsElectronic supplementary information (ESI) available. See DOI: 10.1039/c5nj00125k

A new and simple colorimetric receptor 1 , based on 2,3-diaminomaleonitrile and julolidine moieties, has been synthesized and characterized. 1 showed a selective colorimetric sensing ability for copper( ii ) ions by changing color from yellow to colorless, and could be utilized to monitor Cu 2+ over a wide pH range of 4-12. The detection limit of 1 (2.1 μM) for Cu 2+ ions is much lower than that recommended by WHO in drinking water (30 μM). Moreover, the receptor 1 can also detect fluoride by color change from yellow to orange, distinguishing the fluoride ions effectively from anions such as CH 3 COO − and CN − . It was also found that the 1 -F − complex was reversibly bound and could be simply reverted back through treatment with a proper reagent such as HCl. The sensing mechanism for F − was theoretically supported by DFT and TD-DFT calculations. A chemosensor showed colorimetric sensing for copper( ii ) and fluoride by changing color from yellow to colorless and to orange.