Acid Environment-improved fluorescence sensing performance: A quinoline Schiff base-containing sensor for Cd2+ with high sensitivity and selectivity.

The development of acid environment-applicable fluorescence sensor is challenging but attractive topic, which can achieve the rapid and comprehensive evaluation of total soluble heavy metal content in natural water. In this work, a quinoline-containing Schiff base, AMQD, was utilized as fluorescence probe for Cd2+. Interestingly, the obtained chemosensor exhibited much better fluorescence detection sensitivity and selectivity toward Cd2+ in acidic 10% methanol aqueous solution (pH 4) comparing to those in neutral environment. Initially, the fluorescence emission of AMQD was almost invisible with the absence of metal ions, while a significant turn-on fluorescence response (~425 nm) can be observed with the addition of Cd2+. The fluorescence detection possesses excellent selectivity without the interference of any other metal cation. The recognition ratio between the fluorescence sensor AMQD and Cd2+ was confirmed to be 1:1, and the detection limit was calculated to be 2.4 nM.