A Luminescent Probe for Ratiometric Optical Detection of Hg II and Turn‐On Fluorescent Sensing of Cu II

Luminescent detection of heavy metals continues to be of growing importance considering their increasing inseparable roles in modern day lifestyle. To this end, we report a simple yet interesting thiourea derivative that results in detection of Cu II in a turn‐on fashion via a chemodosimetric redox reaction leading to oxidative cyclization of the chemosensor molecule. Elaborate studies with regard to the sensing process have been performed along with the proposal of a plausible cyclization mechanism of the molecule. Furthermore, the probe optically detects Hg II , yet another heavy metal of prime importance, discernable even to the naked eye. The occurrence of a coordination complex has been proved by UV/Visible spectroscopic experiments as well as ESI‐mass spectrometry.