A Novel Morpholine-Based Rhodamine Fluorescent Chemosensor for the Rapid Detection of Hg Ions.

A novel rhodamine-based receptor bearing a morpholine (RDM) was developed as a fluorescent chemosensor with high selectivity toward Hg. After the addition of Hg to RDM, the color of the solution changed from colorless to pink, and the new absorption band appears at 580 nm. The fluorescent of RDM appears to orange color in the presence of Hg. Upon the addition of Hg, ring-opening of the corresponding spirolactam gives rise to fluorescence, and a 1:1 metal-ligand complex formed.