Anion Detection by a Fluorescent Poly(squaramide): Self‐Assembly of Anion‐Binding Sites by Polymer Aggregation

Winner by aggregate: Incorporating an anion-binding squaramide group into a polymeric architecture results in drastic alterations in the selectivity and magnitude of its anion-induced response, resulting in a sensitive and discriminating turn-on fluorescence sensor for dihydrogenphosphate ions. This unusual behavior is the result of a cooperative, anion-triggered aggregation process (see picture; scale bar: 1 μm).