Fluorescent organic nanoparticles (FONs) of rhodamine-appended dipodal derivative: highly sensitive fluorescent sensor for the detection of Hg2+ in aqueous media

A rhodamine-based receptor consisting of a dipodal framework and a pseudo-cavity compatible with cation binding has exhibited fluorescence recognition of Hg2+ with a detection limit of 0.1 nm in a buffered aqueous medium. The Hg2+ coordination in the receptor pseudocavity resulted in the enhancement of fluorescence intensity due to spirolactam ring-opening.