A novel carbazole-based fluorometric and colorimetric sensor for the highly sensitive and specific detection of Cu2+ in aqueous solution

Abstract

Based on the typical Suzuki coupling reaction and Schiff base reaction, a novel fluorescent molecular PCBW is synthesized and applied as a fluorescence and colorimetric sensor to detect Cu²⁺ in aqueous solution. The PCBW sensor presents the aggregation-caused quenching (ACQ) effect and at 1 × 10⁻⁵ mol L⁻¹ it emits the strongest turquoise fluorescence in the DMSO–H₂O system (f_w = 40%). The sensor exhibits a ‘turn-off’ fluorescent characteristic by adding Cu²⁺, and its fluorescent intensity shows a reliable linear relationship with the Cu²⁺ concentration in the range of 0–6 × 10⁻⁶ mol L⁻¹, with a detection limit of 1.19 × 10⁻⁸ mol L⁻¹. Meanwhile, the PCBW sensor also exhibits the colorimetric sensing from colorless to light yellow. The sensor has good selectivity and anti-interference and its pH application range can be extended from 5 to 10. The intramolecular charge transfer (ICT) is speculated as the main fluorescence mechanism of PCBW. In addition, the sensor presents good reusability and is practicable to detect Cu²⁺ in diverse aqueous samples.