Hg(II)/Fe(III) Turn‐On Fluorescence Response of Rhodamine‐Anthracene Derivatives with Variable Diamine Chain Length

Abstract Two rhodamine‐anthracene derivative probes ( RA1 and RA2 ) were designed and synthesized to incorporate different lengths of diamine chains between the rhodamine and anthracene moieties. Among the 16 different metal ions tested, RA1 exhibited the highest fluorescence enhancement in response to Hg 2+ with a limit of detection (LOD) of 3.76×10 −7 M, while RA2 showed the greatest fluorescence enhancement in the presence of Fe 3+ with the LOD of 2.41×10 −7 M. Notably, RA1 effectively eliminated the interference caused by Fe 3+ during Hg 2+ detection, whereas RA2 successfully eliminated the interference of Hg 2+ during Fe 3+ determination. This response difference between the two ions holds particular importance in scenarios where both heavy metal ions coexist. Additionally, fluorescence microscopy imaging of mouse mammary cancer cells (4T1) under the influence of Fe 3+ demonstrated the potential applications of the probe. This study highlights the significance of a simple molecular design approach in tailoring probe selectivity by modifying the intramolecular flexible chain length.