Rhodamine-Based Fluorescent Probes for Cations

As one kind of the xanthenes, rhodamine dyes have excellent photophysical properties, such as long absorption and emission wavelengths elongated to visible region, high fluorescence quantum yield, and large absorption coefficient, etc. Therefore, rhodamine-based dyes have become one of the perfect chromophores for making fluorescent probes. In the paper, the recent progress in the studies on rhodamine-based fluorescent probes for metal cations are reviewed. Especially systematically discuss about the rhodamine-based fluorescent probes for copper ion, mercury ion and iron ion that are based on the mechanism of screw amide ring "off-on", the mechanism of fluorescence resonance energy transfer and the mechanism of photoinduced electron transfer. The structure, detecting level and applications are discussed in detail. Moreover, the problems and developing trends with this kind of fluorescent probe have also been discussed.