Monolayers of a novel ionoselective butadienyl dye

The novel amphiphilic benzodithia-18-crown-6 butadienyl dye ( 1) forms relatively stable insoluble monolayers on distilled water (collapse pressure of 41 mN/m) and on aqueous subphases containing alkali metal or heavy metal salts (collapse pressures in the range of 27–38 mN/m, respectively). The dye 1 monolayer organization depends on chromophore association and interactions (especially complex formation) with heavy and alkali metal ions as deduced from surface pressure–area and surface potential–area isotherms as well as reflection spectra and Brewster angle microscopy observations. Dye 1 undergoes specific interactions with Hg 2+ and Ag +, respectively (formation of different complexes). Nonspecific interactions have been observed with other salts, such as KClO 4 or Pb(ClO 4) 2. Further, dye 1 monolayers on 1 mM Hg(ClO 4) 2 solution undergo reversible photoisomerization, in contrast to monolayers on water and other aqueous salt subphases.