An Efficient FerroceneDerivative as a Chromogenic,Optical, and Electrochemical Receptor for Selective Recognition ofMercury(II) in an Aqueous Environment.

The synthesis, electrochemical, optical, and cation-sensingpropertiesof two triazole-tethered ferrocenyl benzylacetate derivatives, C36H36O6N6Fe (2) and C23H23O3N3Fe (3), are presented. The binding event of both the receptorscan be inferred either from a redox shift (2, ΔE1/2= 106 mV for Hg2+and ΔE1/2= 187 mV for Ni2+; 3, ΔE1/2= 167 mV for Hg2+and ΔE1/2= 136 mV for Ni2+) or a highly visual output response (colorimetric) for Hg2+, Ni2+, and Cu2+cations. Remarkably,the redox and colorimetric responses toward Hg2+are preservedin the presence of water (CH3CN/H2O, 2/8), whichcan be used for the selective colorimetric detection of Hg2+in an aqueous environment over Ni2+and Cu2+cations. The changes in the absorption spectra are accompanied bythe appearance of a new low-energy (LE) peak at 625 nm for both compounds 2and 3(2, ε = 2500 M–1cm–1; 3, ε =1370 M–1cm–1), due to a changein color from yellow to purple for Hg2+cations in CH3CN/H2O (2/8). [ABSTRACT FROM AUTHOR]