Paracyclophenylenes Carbon Nanohoop Structures. Gary Lloyd Lim. Miljanić Group Meeting / Literature University of Houston ▪ Houston, TX ▪ January 16 th 2009. Great Minds behind the Research. Carolyn Bertozzi PhD—University of California, Berkeley (1993)
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Carbon Nanohoop Structures
Great Minds behind the Research
PhD—University of California, Berkeley (1993)
Predoc—Office of Naval Research (1988–1991)
Diploma—Harvard University (1988)
Professor at University of California, Berkeley
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
RameshJasti—University of California, Berkeley
Jasti, R.; Bhattacharjee, J.; Neaton, J.; Bertozzi, C. J. Am. Chem. Soc.2008, 130, 17646.
California and Its Diversity
CycloparaphenyleneIs a Synthetic Challenge
strained and distorted
radially oriented p-orbitals
provides the curvature and rigidity
necessary for macrocyclization
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.
Macrocylic precursors were prepared
Alonso, F.; Yus, M. Tetrahedron1991, 47, 7471.
Song, Z. Z.; Wong, H. N. C. J. Org. Chem.1994, 59, 33.
It is possible to convert cyclohexadiene moiety to aryl ring
Liu, H.-J.; Yip, J., Shia, K.-S. Tetrahedron Lett.1997, 38, 2253.
What are the Properties of the Cycloparaphenylenes?
Nijegorodov, N. I.; Downey, W. S.; Danailov, M. B. Spectrochim. Acta, Part A2000, 56, 783.
Rings Are in a Staggered Configuration
Even-memberednanohoops, - and  cycloparaphenylenes,
have dihedral angles of 33o and 34o between two adjacent phenyl rings
Strain energies of 28 and 5 kcal mol−1with diameters of 1.7 and 2.4 nm, respectively
Odd-memberednanohoop,  cycloparaphenylene,
has varying dihedral angles of 18o, 30o, 31o and 34o around the carbon nanohoop
Strain energy of 47 kcal mol−1 with a diameter of 1.2 nm
Understanding its properties using Density Functional Theory
Eg = IP – EA – Ee-h
IP = ionization potential
EA = electron affinity
Ee-h = electron-hole interaction energy
Large Stokes shift observed is governed by the degree of structural relaxation in the optically excited state
Enhanced curvature leads to greater sp3 hybridization and increasingly asymmetric p-orbital
Cycloparaphenylenes Are Remarkable