New Pyridine-Bridged Ferrocene–Rhodamine Receptor for the Multifeature Detection of Hg(2+) in Water and Living Cells

[Image: see text] A challenge in the design of optical and redox-active receptors is how to combine a specific recognition center with an efficient responsive system to facilely achieve multifeature detection in biological and environmental analyses. Herein, a novel ferrocene–rhodamine receptor conjugated with a pyridine bridge was designed and synthesized. This receptor can sensitively sense Hg(2+) in aqueous media via chromogenic, fluorogenic, and electrochemical multisignal outputs with a low detection limit and fast response time. Moreover, it can be qualified as a fluorescent probe for effectively monitoring Hg(2+) in living cells. A plausible recognition mode was proposed and rationalized with theoretical calculations.