A ratiometric fluorescent sensor for phosphates: Zn2+-enhanced ICT and ligand competition

A pyrene - terpyridine - Zn conjugate has been synthesized and characterized, where Zn2+ acts as an electron acceptor to enhance molecular ICT with a large emission red-shift (> 100 nm). It showed a ratiometric fluorescence change upon addition of phosphate anions in buffered aqueous solution. The selective response to phosphates or pyrophosphates involved ICT and ligand competition processes.