Click-generated triazole based ferrocene-carbohydrate bioconjugates: a highly selective multisignalling probe for Cu(II) ions

Abstract

Two Cu²⁺-specific colorimetric sensors, based on ferrocene-carbohydrate bioconjugates, 2, C₄₆H₅₆O₂₀N₆Fe and 3, C₂₈H₃₃O₁₀N₃Fe were designed and synthesized in good yields. Both the compounds, 2 and 3, behave as very selective and sensitive chromogenic and electrochemical chemosensor for Cu²⁺ ion in aqueous environment (CH₃CN/H₂O (2:8, v/v). The analytical detection limit (ADL) for receptor 2 was 7.5 × 10⁻⁷ M. The considerable changes in their absorption spectra of 2 and 3 are accompanied by the appearance of a new low energy (LE) peak at 630 nm (2: ε = 1600 M⁻¹ cm⁻¹ and 3: 822 M⁻¹ cm⁻¹). This is further accompanied by a strong colour change from yellow to dark green that allows the prospective for ‘naked eye’ detection of Cu²⁺ ion.