1. Miljanić Group Meeting / Literature University of Houston ▪ Houston, TX ▪ January 16 th 2009 Gary Lloyd Lim Paracyclophenylenes Carbon Nanohoop Structures

2. Great Minds behind the Research Carolyn Bertozzi PhD—University of California, Berkeley (1993) Predoc—Office of Naval Research (1988–1991) Diploma—Harvard University (1988) Professor at University of California, Berkeley Jeffrey Neaton Postdoc—Rutgers University, Physics (2000–2003) The Molecular Foundry, LBNL (2003–2005) PhD (Physics)—Cornell University (2000) Diploma—University of Minnesota (1995) Facility Director—Theory of Nanostructured Materials Facility Joydeep Bhattacharjee— NCN Postdoc Ramesh Jasti— University of California, Berkeley Jasti, R.; Bhattacharjee, J.; Neaton, J.; Bertozzi, C. J. Am. Chem. Soc. 2008, 130, 17646.

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4. Cycloparaphenylene Is a Synthetic Challenge strained and distorted aromatic systems Parekh, V. C.; Guha, P. C. J. Indian Chem. Soc. 1934, 11, 95. Jagedeesh, M. N.; Makuy, A.; Chandrasekhar, J. J. Mol. Model. 2000, 6, 226. radially oriented p-orbitals provides the curvature and rigidity necessary for macrocyclization 3,6-syn-dimethoxy-cyclohexa-1,4-diene

5. Macrocylic precursors were prepared Alonso, F.; Yus, M. Tetrahedron 1991, 47, 7471. Song, Z. Z.; Wong, H. N. C. J. Org. Chem. 1994, 59, 33. 34%

6. It is possible to convert cyclohexadiene moiety to aryl ring Liu, H.-J.; Yip, J., Shia, K.-S. Tetrahedron Lett. 1997, 38, 2253.

7. What are the Properties of the Cycloparaphenylenes? Nijegorodov, N. I.; Downey, W. S.; Danailov, M. B. Spectrochim. Acta, Part A 2000, 56, 783. UV-Vis Absorption Spectra: max ≈ 340 nm Fluorescence Spectra:as carbon nanohoop size decreases, the Stokes shift increases

8. Rings Are in a Staggered Configuration Even-membered nanohoops, [12]- and [18] cycloparaphenylenes, have dihedral angles of 33 o and 34 o between two adjacent phenyl rings Strain energies of 28 and 5 kcal mol −1 with diameters of 1.7 and 2.4 nm, respectively Odd-membered nanohoop, [9] cycloparaphenylene, has varying dihedral angles of 18 o, 30 o, 31 o and 34 o around the carbon nanohoop Strain energy of 47 kcal mol −1 with a diameter of 1.2 nm

9. Understanding its properties using Density Functional Theory E g = IP – EA – E e-h IP = ionization potential EA = electron affinity E e-h = electron-hole interaction energy IP – EA decreases as the number of phenyl rings increase E e-h grows dramatically with the decreasing number of phenyl rings Large Stokes shift observed is governed by the degree of structural relaxation in the optically excited state Enhanced curvature leads to greater sp 3 hybridization and increasingly asymmetric p-orbital

10. Cycloparaphenylenes Are Remarkable 1) Cycloparaphenylenes can be synthesized using a masked aromatic ring moiety 2) Cycloparaphenylenes are subunits of an armchair carbon nanotube 3) Possible route to extended carbon nanotubes using solution-phase chemistry 4) Preparation of carbon nanotubes of a specific chirality