International Research Fellowship Program: Photoswitchable Nanotubes and Nanocapsules Based on Resorcinarene Cavitand Scaffolds

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0601996ShirtcliffThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Laura D. Shirtcliff to work with Dr. Francois Diederich at ETH in Zurich, Switzerland.The research to be completed during the fellowship is a novel and unique extension of the chemistry of molecules that form capsular systems. These molecular capsules have inherently suffered from either too facile of dissociation and subsequent guest removal or from not permitting for guest removal at all unless under forcing conditions. Incorporation of motifs that allow for regulated guest association/dissociation introduces a unique method of control over the molecules. Following extensive preliminary model studies, an elegant synthetic route will be undertaken to prepare nanotubes and nanocapsules that have different mode of perturbing their geometry. The objective is to incorporate light-switchable components into novel resorcin[4]arene cavitands. External stimulation either with light, a change in pH, or a change in temperature transforms the switchable nanotubes or capsules and transmutes their ability to associate with other molecules; a single interaction can cause a global reorganization of structure. In addition, this control can be utilized for molecular transport with selective uptake/release of a guest from its cavity. The switchable nanotubes and nanocapsules are expected to undergo marked geometric inter-conversions that are reversible and repeatable, when exposed to the appropriate stimuli. These novel photoresponsive receptors/switches will be investigated for their shape-dependant host-guest complexation behavior, for guest sensing with the capability of optical readout, and for their potential as new read-write memory devices.