A novel flavone-based fluorescent probe for relay recognition of HSO3(-) and Al(3+).

In this work, a new flavone-based fluorescent probe 3-hydroxy-3'-formylflavone (3HFF) was designed to achieve highly selective relay recognition of HSO3(-) and Al(3+) in DMSO-H2O (2:8, v/v) solution. 3HFF displayed a highly selective response to HSO3(-) with a green fluorescence appearing at 524 nm. Moreover, the in situ generated 3HFF+HSO3(-) system demonstrated eminent relay recognition capability for Al(3+) with a blue fluorescence appearing at 453 nm by the formation of a 1:1 complex between 3HFF and Al(3+) in DMSO-H2O (2:8, v/v) solution. However, only slight change was observed in emission intensity with addition of Al(3+) to 3HFF, and indicated HSO3(-) was essential for the sensing of Al(3+). This work achieves the detection of HSO3(-) and Al(3+) by only one probe and provides another example for this rare combination (anion/metal).