Structure and aggregation of β-cyclodextrin–pyrene–analyte supramolecular sensor: Absorption/emission spectra and simulations

The possibility of using pyrene as a fluorescent probe in a model chemosensor composed of β-cyclodextrin–pyrene (Py–βCD) complex in aqueous solution was studied in the presence of several analytes (A) of different polarity. Absorption bands that prove the formation of the aggregated Py–βCD complex were found in the UV–VIS spectra of aqueous solution of pyrene with added βCD. The aggregate size as measured by dynamic light scattering was found to have a value of 3.2–3.6nm. The aggregate was identified as a 1:2 complex of Py with βCD (Py@2βCD) surrounded by two empty βCD molecules. The ratio I3/I1 of intensity I3 of the third vibronic band at ~26,000cm−1 in the fluorescence spectrum to intensity I1 of the 0–0 transition at ~26,800cm−1 was used as an analytical characteristic of the fluorescent probe. The value of I3/I1 for Py@2βCD is highly sensitive to the presence of several μM of analyte in aqueous solution, and this value is markedly higher than that for pyrene in solution.