Synthesis of Highly Selective Indole-Based Sensors for Mercuric Ion

Two indole-based fluorescent chemosensors 1 and 2 were prepared and investigated characteristic features with transition metal ions. Sensors 1 and 2 were selective for Hg 2+ ion, among a series of metal ions, in aqueous ethanol (H 2 O–EtOH, 1:2, v/v) with association constants of 5.74 × 10 3 and 4.46 × 10 3 M −1 and detection limits of 7.4 and 6.8 μM, respectively. Computational results revealed that sensor 1 or 2 with Hg 2+ ion formed 1:1 complex with a central, sandwich-coordinated Hg 2+ ion. Computational calculations provided evidence that a sandwich-coordinated Hg 2+ ion center was formed and the polyoxyethylene spacer acted as a scaffold for bringing functional ligands into a suitable geometry. Figure We synthesized two indole-based fluorescent chemosensors 1 and 2 of which were selective for Hg 2+ ion among a series of metal ions in aqueous ethanol (H 2 O–EtOH, 1:2). Computational results revealed that sensor 1 or 2 with Hg 2+ ion formed 1:1 complex with a central, sandwich-coordinated Hg 2+ ion