Highly selective sequential recognition of Cu2+ and Cys based on large absorption band shift

Different from commonly-used spectral intensity based recognition, sequential recognition of Cu2+ and Cys by a novel sulfoether-containing bis-thiourea sensor 1 has been achieved based on spectral peak shift. The sensor 1 exhibits high selectivity and sensitivity toward Cu2+ over other competitive metal ions with a 1:2 binding stoichiometry. The recognition of Cu2+ has a detection limit of 5.2 μM and is accompanied by a large bathochromic shift in UV–vis absorption. The in situ prepared 1-Cu2+ ensemble subsequently displays high sensing selectivity to Cys over other amino acids via large hypsochromic shift in the absorption. According to UV–vis titration, the detection limit for Cys was evaluated to be 9.0 μM. This simply and highly selective sequential recognition of Cu2+ and Cys makes the sensor has high application potential in environmental and chemical fields.