Macrocyclic amphiphiles. 1. Properties of calix[4]resorcinarene derivatives substituted with azobenzenes in solutions and monolayers

Photochemical behavior of calix[4]resorcinarenes (CRAs) and O-octaacetylated derivatives having four azobenzene residues at their lower rim in solutions and monolayers is described. UV irradiation of an O-octaacetylated CRA in homogeneous solution gave rise to a photostationary state consisting of a possible six isomers as a result of normal photoisomerization. The compound exhibited reversible precipitation/dissolution cycles in a diluted methanol solution upon alternate irradiation with UV and visible light owing to its scarce solubility of all-trans isomer. Wherease azobenzene chromophores tethered from the cyclic skeleton displayed marked intermolecular interactions in monolayers on a water surface, trans-to-cis photoisomerization took place even in compressed monolayers. The level of the photoisomerizability was dependent on the chemical structure and surface pressures. Monolayers of azobenzene CRAs exhibited the reversible alteration of their areas under a constant surface pressure upon UV and visib...