Nanohoops as Modular Building Blocks to Molecular Cylinders and Machines

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Professor Ramesh Jasti at the University of Oregon is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to develop general methods to use nanohoop molecules as building blocks to self-assemble into precise nanoscale materials with controlled shape and function. Two forms of structures are envisioned: nanotubes and interlocked structures. Novel synthetic approaches are explored to achieve these objectives. The desired products are expected to have structural stability and unique size-dependent optoelectronic properties. The products are rationally designed to perform specific functions in gas adsorption, filtration, mass transport, and molecular switching and sensing. Nanotubes with controlled geometry and diameter are used to prepare one-dimensional materials from fullerenes (soccer-like) carbon-based molecules. Students involved in the project are trained in an interdisciplinary environment and acquire experience in organic synthesis, supramolecular chemistry, and nanoscience. A partnership with the University of Oregon Summer Science Program provides hands-on science experience to groups of students who are traditionally underrepresented in the state of Oregon. The assembly of molecular building blocks into precise nanoscale materials with novel function is a grand challenge at the interfaces of materials science, supramolecular chemistry, and synthesis. While synthetic approaches for the preparation of nanohoops have been developed in the last decade, the self-assembly of these nanohoops into nanoscale materials with controlled shape and function is relatively unexplored. In the first aim of this project, the Jasti research team is exploring weak aryl fluorine interactions as means to guide the self-assembly of carbon nanohoops into noncovalent nanotubes. The nanotubes are used to self-assemble fullerenes into 1D channels, which can then undergo a polymerization reaction to lead to a host of new 1D fullerene nanomaterials. In the second aim of the project, the Jasti group is exploring nitrogen-doped nanohoop analogues and metal-coordination strategies to prepare catenane structures, which would represent simple versions of molecular machines. The Jasti group is probing these new catenane structures for novel properties such as optoelectronic communication through the mechanical bond or ultra-low friction motion on the nanoscale.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.