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A novel multiple target sensor, (E)-5-((4-(diethylamino)-2-hydroxybenzyldene)amino)-1H-imidazole-4-carboxamide (DHIC), was synthesized for fluorescence detection of Zn 2+ and S 2- and colorimetric detection of Fe 3+/2+ in aqueous media. DHIC can operate as a turn "on-off" sequential fluorescent sensor for Zn 2+ and S 2- . Detection limits (1.59 μM and 8.03 μM) for Zn 2+ and S 2- are below the WHO standards (76.0 μM and 14.7 μM). The DHIC-Zn 2+ complex could be reversibly reused with ethylenediaminetetraacetic acid. Importantly, DHIC could image sequentially Zn 2+ and S 2- in living cells. Moreover, DHIC displayed a discriminatory color change from pale yellow to orange yellow to Fe 3+/2+ . The detection limit of DHIC for Fe 3+/2+ (0.73 μM and 1.11 μM) is far below the EPA drinking water standard (5.37 μM). The sensor DHIC could be applied to analyze Fe 3+ in real samples.

A simple and easily synthesized colorimetric and fluorescent receptor 1, based on 4-diethylaminosalicylaldehyde moieties as a binding and signaling unit, has been synthesized and characterized. The receptor 1 has a selective colorimetric sensing ability for copper (II) ion by changing color from colorless to yellow in aqueous solution, and could be utilized to monitor Cu(II) over a wide pH range of 4-11. In addition, the detection limit (12μM) of 1 for Cu(2+) is much lower than that (30μM) recommended by WHO in drinking water, and its copper complex could be reversible simply through treatment with a proper reagent such as EDTA. Moreover, receptor 1 exhibited both a color change from colorless to yellow and fluorescence enhancement with a red shift upon addition to F(-) in DMSO. The recognition mechanism was attributed to the intermolecular proton transfer between the hydroxyl group of the receptor and the fluoride., (Copyright © 2014 Elsevier B.V. All rights reserved.)