A Piperazine Linked Rhodamine‐BODIPY FRET‐based Fluorescent Sensor for Highly Selective Pd<sup>2+</sup> and Biothiol Detection
Fung‐Kit Tang, Yanyan Chen, Daniel Nnaemaka Tritton, Zongwei Cai, Ken Cham‐Fai Leung
Abstract
Abstract A class of rhodamine‐based fluorescent sensors for the selective and sensitive detection of Pd 2+ metal ions in aqueous media has been developed. A rhodamine‐based sensor PMS and a rhodamine‐BODIPY Förster resonance energy transfer (FRET)‐pair sensor PRS have been incorporated with a piperazine linker and an O−N−S−N podand ligand for specific recognition of Pd 2+ ion. Both probes displayed colorimetric and fluorescent ratiometric changes when exposed to Pd 2+ , due to their spirolactam rings opening and restoring rhodamine conjugation. PRS is highly selective to Pd 2+ over 22 other metal ions, showing a 0.6‐fold ratiometric difference at I 600nm / I 515nm . Additionally, the lactam ring in Pd 2+ coordinated PRS‐Pd could be switched back to the closed form in the presence of various thiols, providing a “red‐green traffic light” detection mechanism between red and green emission. Furthermore, PRS showed excellent cell viability and was successfully employed to image Pd 2+ and the PRS‐Pd complex ensemble could interchangeably detect biothiols including glutathione (GSH) in A549 human lung cancer cells.