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

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.