Two novel fluorescent chemosensors in which an aza-crown is linked to 4-coumaryl fluorophores by a methylene spacer have been synthesized for sensing saxitoxin. Fluorescence enhancement was observed upon binding of the dicationic toxin molecule, whereas several metal ions produced no effect.

Fluorescent organic chemosensors for the detection of divalent copper with high selectivity and sensitivity are the subject of intense research in the recent years. Structurally, ionophore and fluorophore are two essential parts determining the resultant performance of the chemosensor. While much work has been focused on designing highly selective ligands, little attention has been paid to the possible influence of ionophore-fluorophore interaction