Array‐Based Discrimination of Phenolic Acids in Water at Near‐Neutral pH with Chromogenic and Fluorescent Cyclodextrin‐Based Supramolecular Sensors

Abstract Phenolic acids are a class of poorly water‐soluble organic compounds with antioxidant properties that contain a carboxylic acid and a phenol group, common in plants. We used hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as a supramolecular host to sense phenolic acids in water near physiological pH. The analytes’ complexation was monitored through changes in the optical absorption and emission properties of a series of six organic dyes, acting as indicators in a displacement assay, that were selected from screening a panel of 17 candidates. Binding constants between these dyes and the HP‐β‐CD were in the 10 2 –10 4 range. We showed that the nuanced differences in the dyes’ optical signatures associated with this displacement process, when analyzed and summarized using multivariate analysis algorithms such as principal component analysis (PCA), can be used to successfully discriminate among six phenolic acids, and to identify six unknown samples of such acids, down to a 0.02 mM concentration.