Selective fluorescent sensor for mercury(II) ion based on an easy to prepare double naphthalene Schiff base

Abstract

A fluorescent mercury sensor allowing for cheap, sensitive, and highly selective detection of Hg2+ is described. This sensor combines two naphthalene groups as signaling subunits and the presence of imine group which was oxidized to amide with DMSO and Hg2+ confers the coordination capacity required to coordinate Hg2+ ion. This double-naphthalene Schiff base chemosensor (G, Scheme 2) is readily soluble in DMSO and the solution give colorless fluorescent signal, when sensor G reacts with Hg2+ the solution give blue fluorescent signal. The MS, IR and 1H NMR data suggest that the presence of Hg2+ leads to the formation of OHg2+N, which is then converted to a structural change, the CN of G was oxidized to OCNH of G1 (Scheme 1). The test strip based on G was fabricated, which could act as a convenient and efficient Hg2+ test kit. The event is useful for fluorescent detection of Hg2+ at the micromolar level with a detection limit of 5.595×10−8M in DMSO medium.