Turn-on luminescent sensing of metal cations via quencher displacement: Rational design of a highly selective chemosensor for chromium(III)

摘要

A highly selective luminescent chemosensor for Cr~(3+) in aqueous solution was assembled by a low-selectivity luminogenic receptor with Cu~(2+) as a metal quencher. Three tetranitrogen chelating sites were integrated into the multichannel receptor with a tris(1,10-phenanthroline) ruthenium(II) luminophore at the core. This receptor (2) exhibits chelating affinity for many transition-metal cations, among which Cu~(2+) efficiently quenches the emission. The further addition of Cr~(3+) into the Cu~(2+)-titrated solution of 2 results in a metal-exchange reaction and a sensitive turn-on luminescence response highly selective over other metal cations. The quencher displacement sensing strategy in this design can be a simple but efficient approach for OFF-ON luminescent sensing of metal cations that inherently lack selective ligands.