Order and structure in Langmuir-Blodgett mono- and multilayers of resorcarenes

Langmuir-Blodgett (LB) films of 19 resorcarenes and pyrogallenes have been assembled. It has been shown that a wide variety of structure, in both the bowl rim of these molecules and in the pendant legs, can be tolerated in the deposition process, except when these lead to very rigid monolayer structures. The behavior of these resorcarenes and pyrogallenes under pressure on the water surface has been studied through their II-A curves, which are presented and interpreted. Functionalization of the bowl-rim hydroxyl groups notably reduces collapse pressures and increases the surface area. This is consistent with destabilization of the cone conformer of these molecules. LB multilayers have been examined by low-angle X-ray diffractometry, and the results reveal the significance of interdigitation of pendant legs, the disruption of multilayer packing by bulky substituents, and the requirement of long straight hydrophobic chains for efficient multilayering.