Selective sensing and efficient separation of Hg2+ from aqueous medium with a pyrene based amphiphilic ligand

Abstract

We have synthesized a new fluorogenic compound L, which can selectively bind and sense Hg²⁺ in aqueous medium over a broad pH range. It exhibits excellent selectivity for Hg²⁺ over a large number of competitive cations (Fe³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Ag⁺, Cd²⁺, Pb²⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺). The sensing ability of the ligand is studied by fluorescence and UV-vis spectroscopy. Hg²⁺ present even in a nanomolar range can be detected. The effectiveness of L for detecting Hg²⁺ inside live human cancer cells (HeLa) is also examined. The hydrophobic part of L is efficiently employed for the quantitative extraction of Hg²⁺ from an aqueous medium into the organic layer. The extraction ability of L is also estimated by NMR, fluorescence and atomic absorption spectroscopy showing that approximately 99% of the Hg²⁺ ions are extracted. These results imply that the compound has potential application for sensing and removal of Hg²⁺ ions from waste water in a large cross-section of mercury threatened zones around the world.