Characteristics of monolayers of calix[4]resorcinarenes derivatives havingazobenzene chromophores

The adsorption behavior of calix[4]resorcinarenes (CRAs) and their O-carbox ylmethylated and O-hydroxyethylated derivatives (CRA-CMs and CRA-HEs) from solutions was studied, aiming at the fabrication of self-assembled monolaye rs on polar surfaces of amorphous solid such as silica, These macrocyclic a mphiphiles displayed considerably enhanced adsorption constants, due to the contribution of their multi-site adsorptivity, to form densely packed mono layers simply by immersing a silica plate in dilute solutions of the amphip hiles. CRA and CRA-CM bearing four azobenzene moieties at the lower rim of the cylindrical skeleton were prepared to modify a silica surface with phot o-reactive monolayers by the surface adsorption technique. Adsorbed monolay ers exhibited efficient E-to-Z photoisomerizability and applied to the phot ocontrol of alignment of liquid crystals and of dispersibility of colloidal silica. (C) 1999 Elsevier Science S.A. All rights reserved.