3A novel carbazole-based AIE-active fluorescent sensor for fast and ultrasensitive detection of Cu²⁺ and Co²⁺ in...

A novel phenyl-carbazole-based fluorescent sensor (PCBP) has been synthesized and investigated to selectively detect Cu²⁺ or Co²⁺. The PCBP molecule exhibits the excellent fluorescent property with the aggregation-induced emission (AIE) effect. In given THF/normal saline (f_w = 95%) system, the PCBP sensor shows turn-off fluorescence performance at 462 nm with Cu²⁺ or Co²⁺. It reveals excellent characteristics of good selectivity, and ultra-high sensitivity, strong anti-interference ability, wide pH applicable range, as well as ultra-fast detection response. The limit of detection (LOD) of the sensor reaches 1.1 × 10^-9 mol·L^-1 and 1.1 × 10^-8 mol·L^-1 for Cu²⁺ and Co²⁺ in turn. The formation mechanism of AIE fluorescence of PCBP molecules is attributed to the synergistic effect of intramolecular & intermolecular charge transfer (I&ICT). Meanwhile, the PCBP sensor has good repeatability for the detection of Cu²⁺, and performs excellent stability and sensitivity for the detection of Cu²⁺ in real water sample. The PCBP-based fluorescent test strips present reliable capacity for the detection of Cu²⁺ and Co²⁺⁺ in aqueous solution.