Improved sensing of metal ions via abnormal enhancement of the anti-stokes emission of the near-infrared fluorescent probe

Abstract

Sensing of toxic and heavy metals is of great importance for protecting environment and health monitoring. Here we demonstrate an improved fluorescent probe operating in the near-infrared (NIR). The probe represents a NIR tricarbocyanine dye with 2,2′-dipicolylamine meso-group which is able to chelate zinc, cobalt and palladium ions. We show that the probe operation via monitoring of the anti-Stokes photoluminescence provides much better sensitivity of the probe compared to its Stokes photoluminescence. Particularly, it is shown that the anti-Stokes photoluminescence increases by more than an order of magnitude and can reveal additional features of the dye-metal complex not observed via the Stokes emission.