Calix-4-resorcinarene monolayers and multilayers: Formation, structure, and differential adsorption

A tetrapodal calix-4-resorcinarenethiol has been immobilized in a gold-thiol monolayer. Adsorption of a variety of polar substrates into the monolayer has been demonstrated by Fourier transform infrared spectroscopy. For many substrates, adsorption is reversible but not in the case of hydroxylactones for which adsorption appears to be followed by scission of the lactone ring and acylation of hydroxyl groups on the periphery of the bowl of the resorcarene. Evidence for this unusual behavior is presented. Some calix-4-resorcinarenes have been found to form multilayers under certain conditions. These multilayers have regular periodic rather than random structures and are able to adsorb substrates selectively. These multilayers disperse in polar solvents, but when pendant chains in a calix-4-resorcinarene multilayer are terminated by vinyl groups, UV irradiation apparently cross-links the chain with resulting stability of the multilayer and resistance to dispersal.