ORGN 119 |
| Desymmetrized [2]catenanes serve as a role model of controllable molecular motors. Efficient rotary movements can be implemented only if precise control of translational isomerism is achieved. The synthesis of such compounds remains challenging, as it requires the selection of right recognition pairs with different strength and their proper assembly. Here we describe an efficient templated synthesis of desymmetrized donor-acceptor [2]catenanes where precise location control of the products' ring components was implemented. The templating takes effect from the formation of pseudorotaxanes between p-rich crown ethers and a p-deficient pyromellitic (PmI) acceptor, followed by macrocyclization around the crown ether component through the creation of a bipyridinium (BPy) unit as a secondary, yet better acceptor. The crown ether components preferably encircle the BPy unit rather than the PmI unit in the resulting [2]catenanes, as indicated by 1H NMR and UV-vis spectroscopic studies in solution and X-ray structural analysis in the solid state. The demonstrated excellent translational selectivity could lead to high fidelity molecular switches for usage in the growing field of molecular electronics.
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Total Synthesis, Materials, Devices and Switches, Molecular Recognition and Self-Assembly, Biologically-Related Molecules and Processes
8:00 PM-10:00 PM, Sunday, August 19, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Organic Chemistry |
