A triazole based triferrocene derivative as a multiresponsive chemosensor for Hg(II) ion and a redox chemosensor for H<inf>2</inf>PO<inf>4</inf>^- ion

A triazole tethered triferrocene receptor, C40H 40O2N6Fe3 3, has been synthesized from the reaction of mono-alkynyl substituted ferrocene, 1 and 1,1′-bis-(azidomethyl)ferrocene, 2. Consequently the cation and anion sensing properties of 3 have been examined. The receptor 3 was found to be highly selective electrochemical (ΔE11/2=145mV, ΔE21/2=92mV), optical and chromogenic chemosensor for Hg2+ ion in aqueous environment. The substantial changes in its absorption spectra are accompanied by the appearance of a new low-energy peak at 631 nm (ε = 3400 M-1 cm-1). This is also accompanied by a strong color change from yellow to purple, that allows a prospective for the "naked eye" detection of Hg2+ ion over other competitor cations such as Pb2+, Cd2+, Zn2+, etc. In addition, among various anions, 3 shows a distinct electrochemical recognition of dihydrogen phosphate anion by its multiple H-bonding (C-H⋯O), which is supported by electrochemical (large cathodic shift ΔE1/2 = -175 mV) and 1H NMR titration results. © 2012 Elsevier B.V. All rights reserved.