A novel rhodamine-based colorimetric and fluorescent sensor for the dual-channel detection of Cu2+ and Fe3+ in aqueous solutions

A novel xanthene dye was designed and synthesized from rhodamine B, hydrazine hydrate and 4-chloro-7-nitro-2,1,3-benzoxadiazole. The sensing activity of the new rhodamine dye toward metal ions was carefully investigated. In H2O/CH3CN (1/1, v/v), the dye showed high selectivity and sensitivity to Cu2+ by remarkable absorption and fluorescence enhancement, while in H2O/CH3CN (99/1, v/v), the dye behaved as a high selective and sensitive turn-on fluorescent sensor for Fe3+. The detection was essentially insensitive to H+ concentration between pH 2.6 and 10.9. The sensing mechanism was explored by IR and LC-mass spectroscopic techniques and the LC-mass analysis results indicated that a 1:1 complex was formed between Cu2+ (or Fe3+) and the sensor. (C) 2013 Elsevier Ltd. All rights reserved.