Figure 21.

Non-macrocyclic fluorescent probes for anions. (a) Pyrene-based 49 is an effective sensor for CN⁻ anion, which reacts with the central carbon of the benzothiazolium component to form the emissive species 50 [123]; (b) BODIPY-functionalised boronate ester 51 responds to both CN⁻ and F⁻, even in the presence of various other competing anions. F⁻ triggers quenching and a blue shift in the emission of 51 from 599 nm to 579 nm, and new bands at 509 nm and 639 nm; CN⁻ also brings quenching and a blue shift to 575 nm, plus a single new emission at 478 nm [124].