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FULLERENES

FULLERENES. Aaron Koga May 1, 2007 Physics 441. OUTLINE. Introduction to Fullerenes Some properties A few different fullerenes, applications, interesting things C 60 Endoheral fullerenes, bucky onions Fullerite Medicine. INTRODUCTION (History).

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FULLERENES

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  1. FULLERENES Aaron Koga May 1, 2007 Physics 441

  2. OUTLINE • Introduction to Fullerenes • Some properties • A few different fullerenes, applications, interesting things • C60 • Endoheral fullerenes, bucky onions • Fullerite • Medicine

  3. INTRODUCTION (History) • Discovered 1985, Kroto, Smalley, and Curl • Nobel Prize chemistry, 1996: 3 scientists for discovery of Fullerenes • Named after Richard Fuller (Architect) Montreal Biosphere by Fuller

  4. INTRODUCTION (What is a Fullerene?) • Carbon allotropes • Hollow sphere (buckyball), ellipsoid, tube (buckytube, nanotube) • Similar structure to graphite: • Hexagons • Pentagons (curvature) • Euler: 12 pentagons to make sphere

  5. INTRODUCTION (Production) • Before: vaporization laser • 1990 • Graphite electrodes • Fill chamber with He (inert gas), ~100 torr • Run current through graphite • Get black soot • ~10% C60 • Some larger fullerenes

  6. PROPERTIES(Structure) • Stable, but not totally unreactive • In graphite: • sp2 bonding • Planar, 120o • Fullerenes: • [6,6] double bonds, hexagons • [6,5] single bonds, pentagons to hexagons • [6,6] are shorter than [6,5] • Sphere, so not planar  angle strain • Estimated that 80% of E-formation due to strain • Strain concentrated on pentagons  structures with out touching pentagons are more stable (C60)

  7. PROPERTIES(Other) • Slightly soluble in some solvents • Toluene, carbon disulfide, etc. • In water: large clusters (nC60) of 250-350 nm • Toxic? • 2004: found increase in cellular damage to fish with ~.5ppm in water • 2005: computer simulation found deformation of DNA by C60 in water • Wave-particle duality with λ=3pm, 1999

  8. C60 • Buckminster Fullerene • Smallest structure with no pentagons touching • ~.7 nm diameter • Melting point ~ 550K

  9. Endohedral Fullerenes • Have atoms, clusters, molecules inside • Endohedral Metallofullerenes: • Metals with the fullerene • 1985: La@C60 (@ for “inside”) • Electrons donated by metal to C60 • Different size charge transfers ex. La2@C80 (2 e-) vs. Sc3N@C80 (6 e-) • Non-metal doped fullerenes: • Ex. He@C60, Ne@C60 • Forms when fullerene in ~3 atm of noble gas • Noble gas is exactly in center of structure

  10. Bucky Onions • One fullerene inside another • Up to 70 layers observed • Nanotube generation normally produces some onions

  11. Fullerite • Bulk solid C60 • FCC structure • Ultrahard Fullerite: • 310±40 GPa hardness • Diamond: <240 GPa (sometimes 150 GPa)

  12. Fullerite • A3C60,A6C60 • Alkali metal cations for each sphere • 3 metal holes (grey) per sphere (blue) • A3C60: conductor A6C60: insulator at room temp

  13. Fullerite • A3C60 becomes super conducting • Lattice constant, ao, changes to accommodate the metal cation • Different Tc

  14. Fullerenes in Medicine • Useful because of size, stability, hydrophobia • HIV (Human Immunodeficiency Virus) inhibitor • HIVP has cylindrical active site with hydrophobic amino acids • C60 is about same size as the cylinder • Possible inhibiting of HIVP • Drug delivery, attach to outside of cage • Improve MRI (Magnetic Resonance Imaging): • Gd3+ used to improve imaging, but toxic metal • When in fullerene even safer than current method • Stabilize other reactive species (not only in medicine)

  15. References “Fullerene.” http://en.wikipedia.org/wiki/Fullerene Unwin, Peter. “Fullerenes (an overview).” http://www.ch.ic.ac.uk/local/projects/unwin/Fullerenes.html Bleeke, John R. and Frey, Regina F. “Fullerene Science Module.” http://www.chemistry.wustl.edu/~edudev/Fullerene/fullerene.html “Bucky Onion.” http://www.3dchem.com/molecules.asp?ID=218 “Diffraction and Interference with Fullerenes.” http://www.quantum.univie.ac.at/research/matterwave/c60/ Dagani, Ron. “Cage Chemistry.” http://pubs.acs.org/cen/coverstory/8024/8024fullerenes.html

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