A multiresponsive two-arm ferrocene-based chemosensor molecule for selective detection of mercury

Abstract

The preparation, electrochemical, electronic, and cation sensing properties of an indole–ferrocene–indole triad, are presented. A salient feature of this new structural motif is that the redox-active organometallic fragment is linked to the indole rings by unsaturated nitrogen functionalities. Triad 4 behaves as a highly selective dual-redox and chromogenic chemosensor molecule for Hg²⁺ cations: the oxidation redox peak is anodically shifted (ΔE_1/2 = 210 mV), and the low energy band of the absorption spectrum is red-shifted (Δλ = 120 mm), upon complexation with this metal cation. This change in the absorption spectrum is accompanied by a dramatic colour change from orange to green which allows the potential for “naked eye” detection. ¹H NMR as well as DFT calculations have been carried out to get information about the molecular sites which are involved in bonding.