Bis-pyridobenzene as a fluorescence light-up sensor for Hg2+Ion in water

Abstract

Heavy metal ion such as mercury is a highly toxic in all its oxidation states in the environment. Mercury exposure causes a variety of adverse environmental and health problems, such as brain damage, neurological disorder, damage of immune system etc. Mercuric ions (Hg2+) being highly water-soluble are easily bioavailable for humans and animals through ingestion leading to many of the physiological problems. Thus, continued alarm over mercury pollution has prompted increasing interest in the design of new fluorescent probe for mercury detection in biological and environmental samples. Therefore, we synthesize meta-di-4-methylpyridyl benzene (m-DPB) core as a possible fluorescent probe for Hg2+ detection. The probe shows a dual fluorescence emission at long wavelength region (350, 425nm) indicating its potential use as a probe in aqueous medium which could be utilized for sensing of metal ions. Herein, we report the synthesis of that new and novel fluorescence probe and its use in switch-on sensing of Hg2+ ion. The probe is very simple in design and is found to be highly sensitive for sensing Hg2+ ion in the presence of other interfering metal cations with a high binding constant for 1:1 probe-Hg2+ complexation and high sensitivity (1μM) in water. All the observations are evident from the absorption and fluorescence spectroscopic studies. A theoretical calculation and NMR titration suggest that the probe binds Hg2+ through the coordination with two pyridyl nitrogens.