A ratiometric and colorimetric probe for detecting Hg 2+ based on naphthalimide-rhodamine and its staining function in cell imaging.

In this work, a rhodamine derivative was developed as a colorimetric and ratiometric fluorescent probe for Hg 2+ . It exhibited a highly sensitive fluorescence response toward Hg 2+ . Importantly, studies revealed that the probe could be used for ratiometric detection of Hg 2+ , with a low detection limit of 0.679 μM. The mechanism of Hg 2+ detection using compound 1 was confirmed by ESI-MS, 1 H NMR, and HPLC. Upon the addition of Hg 2+ , the rhodamine receptor was induced to be in the ring-opening form via an Hg 2+ -promoted hydrolysis of rhodamine hydrazide to rhodamine acid. In addition to Hg 2+ detection, the naphthalimide-rhodamine compound was proven to be effective in cell imaging.