Pseudo‐Crown Ether‐based Host for the Recognition of Pd²⁺ and Fe³⁺ ions in Water

Abstract

The development of coordination‐based host for the detection of heavy metal ions in aqueous medium is a challenging task. We report 1,8‐naphthalimide‐based pseudo‐crown ether host which possess hexaethylene glycol chain for the selective binding of Pd2+ and Fe3+ with higher affinity for Pd2+ over Fe3+ ions. The lowest detection limits for Pd2+ and Fe3+ ions are 2.5 nM and 15 nM, respectively. Job's and Hill plot showed 1 : 1 stochiometric complexation between NHG:Mn+ with binding constants of 1.4×104 M−1 (Pd2+) and 1.5×103 M−1 (Fe3+). The CIE plot of NHG showed 90 % blue colour purity in CHCl3 solution. In solid‐state, the CIE plot of NHG showed blue‐green colour with 52.7 % green colour purity and high quantum yield (ϕ=0.0643). The flake‐like aggregates of NHG transformed into spherical structure upon interaction with Pd2+ as confirmed by microscopic and light scattering studies.