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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.

Composite materials, consisting of a polymer matrix and a crown ether derivative immobilised in it, and possessing photochromic properties, have been obtained and investigated. The possibility of using them to detect mercury(II) cations has been shown.

A combination of the photosensitive and ion-selective properties of thin polymer films with immobilised amphiphilic crown-ether styryl dye (in particular dye interaction with alkaline earth metal ions) gives evidence that such films can serve as a prototype of chemosensors with optical signal detection.

The synthesised amphiphilic benzodithia-15-crown-5 butadienyl dye forms stable monolayers on distilled water (up to 47 mN m–1) and undergoes specific interactions (complex formation) with Hg2+ or non-specific interactions with K+, as follows from surface pressure – and surface potential – molecular area isotherms.

Benzothiazolium dyes containing a crown ether ring are able to complex selectively metal ions in solution. The dyes exhibit strong photochromism which allows the efficiency of their complexation with metal ions to be controlled by light. Hence, being reconstructed into the lyposomes or into the cellular membrane, the dyes could play a role of potential light-controlled selective regulators of transmembrane transport of metal ions. The molecular background of the processes of dye-ion complexation and dyes photoisomerisation should be investigated in the range of concentrations 10-5–10-8 M if the overall patterns of dye structure-function relationships in terms of their biological applications need to be clarified.