A rhodamine-based "turn-on" fluorescent probe for Fe3+ in aqueous solution.

A water-soluble "turn-on" fluorescent probe (RD1) for Fe(3+) based on rhodamine B was designed and synthesized. The fluorescent probe showed "turn-on" fluorescent and colorimetric responses to Fe(3+) with a high selectivity in water containing less than 1% organic cosolvent. Furthermore, bioimaging investigations indicated that the new probe was cell permeable and suitable for monitoring intracellular Fe(3+) in living cells by confocal microscopy with low cytotoxicity.