Rhodamine based derivative and its zinc complex: synthesis and recognition behavior toward Hg(II)

A simple fluorescent probe, which contains rhodamine and aminoquinoline moieties, was designed and prepared for selective detection of Hg2+ in acetonitrile. RbQ exhibited high selectivity and sensitivity toward Hg2+ over other common metal ions. The recognition of RbQ toward Hg2+ can be detected by fluorescence spectra, absorption spectra, and even by naked eyes. The binding ratio of the RbQ–Hg2+ complex was found to be 1:1 according to Job plot experiment, and the limit of detection was 1.05×10−7 M. Moreover, the prepared complex RbQ–Zn2+ (RbQZ) could detect Hg2+ in a ratiometric way and showed lower limit of detection (2.95×10−8 M) than RbQ in the same condition. Finally, we also demonstrated that the aminoquinoline–zinc complex could be served as a new and effective FRET donor for rhodamine derivatives.