Fluorometric sensing of Hg²⁺ ions in aqueous medium by nano-aggregates of a tripodal receptor

Two new tripodal receptors (1–2) have been synthesized and characterized by various spectroscopic techniques. The nano-aggregates of 1 and 2 (N1 and N2) have been prepared by a re-precipitation method in aqueous medium and have shown different photo-physical properties. Nano-aggregates of 1 (N1) can selectively recognize Hg²⁺ in aqueous medium in the presence of other metal ions with enhancement in fluorescent intensity. The response was linearly proportional to the concentration of Hg²⁺ in the range 0–10 μM with a detection limit of 2.4 nM. The mechanism of selective binding of Hg²⁺ by N1 has also been supported by theoretical studies. To the best of our knowledge, this work represents the first report on substituted thiourea based nano-aggregates for nano-molar detection of mercury in aqueous medium.