The Role of the Structural Organization of Sulfur-Containing BODIPY Derivative Ultrathin Films in Supramolecular Recognition of Mercury Cations

The paper reports the synthesis of a sulfur-containing amphiphilic derivative, BODIPY B2S, as well as the methods for its purification, and the characteristics of this compound (NMR, IR spectroscopy, mass spectrometry), which can be used as a chelator for mercury(II) cations. The effect of the film structural organization on the efficiency of supramolecular recognition of Hg2+ ions has been determined on the basis of the analysis of the structure, properties, and phase behaviour of B2S in ultrathin films on liquid and solid substrates. The structural changes accompanying molecular transitions in planar systems have been studied using Langmuir monolayer compression isotherms, in situ reflection-absorption UV−Vis spectroscopy, optical absorption spectroscopy, and fluorescence spectroscopy. It has been shown that the disruption of dye associates upon complexation leads to the enhancement of monomer emission and alters the fluorescence colour of Langmuir–Blodgett films formed at a high surface pressure. This phenomenon can serve as a convenient diagnostic indicator of mercury cation binding.