Naphthalimide-Piperazine Derivatives as Multifunctional "On" and "Off" Fluorescent Switches for pH, Hg and Cu Ions.

Novel 1,8-naphthalimide-based fluorescent probes and were designed and screened for use as chemosensors for detection of heavy metal ions. Two moieties, methylpyridine () and hydroxyphenyl (), were attached via piperazine at the C-4 position of the napthalimide core resulting in a notable effect on their spectroscopic properties. and are pH sensitive and show an increase in fluorescence intensity at around 525 nm (switch "on") in the acidic environment, with p values at 4.