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

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 behaves as a highly selective dual-redox and chromogenic chemosensor molecule for Hg(2+) cations: the oxidation redox peak is anodically shifted (DeltaE(1/2) = 210 mV), and the low energy band of the absorption spectrum is red-shifted (Deltalambda = 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. (1)H NMR as well as DFT calculations have been carried out to get information about the molecular sites which are involved in bonding.