PNNL

Abstract

Increased levels of Nitrate (NO3-) anion in the environmentcan be detrimental to human health. To address the need for a robust, cost-effective, scalable technology for rapid, selective, sensitive and interference free in-situ nitrate detection, here in this work, we report colorimetric/luminescent sensors based on hybrid materials. The hybrid materials are based on a square-planar platinum(II) salt [Pt(tpy)Cl]PF6 (tpy = 2,2';6',2?-terpyridine) supported on mesoporous silica (Controlled Pore Glass beads). The hybrid materials undergo vivid change in color and luminescence upon exposure to aqueous NO3- anions at pH =0 caused by a rearrangement of the crystal lattice of the platinum salt that leads to an extended Pt···Pt···Pt interactions, along with a concomitant change in the electronic structure. Further, by enhancing the surface area by layering the Pt salt to onto mesoporous silica, we were able achieve a detection limit of 0.05 mM (3.1 ppm), which is sufficiently lower than the ambient water quality limit of 0.16 mM (10 ppm) set by United States Environmental Protection Agency.