Reactions of Folded Molecules in Water

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The majority of processes that take place in the chemical industry use organic solvents, solvents that are generally obtained from petrochemicals. Adapting these processes to the "greenest" solvent - water - remains a challenge. This project to be conducted by Professor Julius Rebek at The Scripps Research Institute uses synthetic, container-shape, molecules for reactions in water. The "containers" act as nanovessels that show robust stability and can be used and re-used over a wide range of conditions. A broader impact of this research is the benefit of developing sustainable chemistry. Another impact is the discovery of new molecules for use in water-proof coatings and nanomachines. Postdoctoral researchers benefit from learning how research projects translate from chemical discovery to applications in new materials.The chemistry of molecules confined to small containers - nanoscale compounds known as cavitands - is a relatively new undertaking. This research takes advantage of an early discovery that long-chain organic compounds assume unusual, folded shapes within the cavitand's space. The folded shapes, induced by hydrophobic forces, push the substrate's ends together and promote large-ring cyclization processes. The cavitands act as templates. Folding also blocks some sites on the chain and exposes others to reactions with agents in the aqueous medium. The blocking action promises new chemical pathways for remote carbon-hydrogen activation in functionalization reactions that typically lead to 5 or 6-membered ring sizes. Functional groups that are remote in extended molecules are brought into proximity when folded in cavitands. The functions no longer act independently and can affect each other's reactivity; showing the consequences of this "entanglement" is one of the basic science novelties expected from this research. The practical consequences may include synthetic methods for access to molecules that cannot be made by conventional means.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.