The document discusses acenes, which are polycyclic aromatic hydrocarbons composed of linearly fused benzene rings. It describes acene applications and degradation mechanisms, as well as lessons learned about substituent effects and how they can be used for band-gap engineering. The document also covers fullerenes, carbon nanotubes, and using fullerene-acene chemistry to create larger acenes and nanocarbons like cyclacenes and single-walled carbon nanotubes.

1. Acenes, Fullerenes and Carbon Nanotubes Glen P. Miller Department of Chemistry and Materials Science Program University of New Hampshire Columbia University September 17, 2008

2. Acenes: Polycyclic aromatic hydrocarbons composed of linearly annelated benzene rings (Clar, E. Polycyclic Hydrocarbons ; Academic Press Inc: London, 1964; Vol. 1, pp 4-5)

3. Acene Applications

5. Acene Degradation: Competing Photo-Oxidation Mechanisms

6. Substituent Effects on Acene Longevity

7. Kinetics of Photo-Oxidation “ Substituent Effects in Pentacenes: Gaining Control Over HOMO-LUMO Gaps and Photo-oxidative Resistances,” submitted to JACS

8. Kinetics of Photo-Oxidation “ Substituent Effects in Pentacenes: Gaining Control Over HOMO-LUMO Gaps and Photo-oxidative Resistances,” submitted to JACS

9. Evidence for Singlet Oxygen Chemistry

10. Lessons Learned: Location, Location, Location

11. Lessons Learned: Steric Resistance is Important “ Substituent Effects in Pentacenes: Gaining Control Over HOMO-LUMO Gaps and Photo-oxidative Resistances,” submitted to JACS

12. Lessons Learned: ED and EW Groups Offer Unique Electronic Effects “ Substituent Effects in Pentacenes: Gaining Control Over HOMO-LUMO Gaps and Photo-oxidative Resistances,” submitted to JACS

13. Steric & Electronic Effects Combined “ Substituent Effects in Pentacenes: Gaining Control Over HOMO-LUMO Gaps and Photo-oxidative Resistances,” submitted to JACS

14. Arylthio and Alkylthio Substituted Pentacenes are the Big Winners

15. Thin-Film Characteristics “ Substituent Effects in Pentacenes: Gaining Control Over HOMO-LUMO Gaps and Photo-oxidative Resistances,” submitted to JACS

16. HOMO & LUMO Energies

17. HOMO & LUMO Energies and Gaps pentacene derivative (t 1/2 ) E 1/2 [O] a (mV) E 1/2 [red] a (mV) E HOMO (eV) E LUMO (eV) E g,EChem (eV) low energy  max (nm) E g,optical (eV) c E HOMO,DFT , E LUMO,DFT (eV) E g,DFT (eV) 1 (1140) 849, 1093 -1099 -5.17 -3.36 1.81 624, 575, 534 1.86 -5.20, -3.03 2.17 2 (750) 755, 936 -1229, -1726 -5.07 -3.26 1.81 617, 570, 529 1.88 -5.08, -2.89 2.19 3 (620) 899 -1227 -5.21 -3.24 1.97 605, 559, 520 1.94 --- --- 4 (520) 789 -1054 -5.11 -3.42 1.69 643, 591, 548 1.81 -5.08, -3.07 2.01 5 (220) 713 -1485 -5.03 -2.99 2.04 605, 558, 520 1.95 --- --- 6 (40) 695 -1478 -5.01 -3.00 2.01 604, 557, 518 1.96 -4.93, -2.71 2.22 7 (13) 638, 1372 -1543 -4.95 -2.93 2.02 618, 569, 529 1.90 --- --- 8 (9.0) 627, 1224 -1430 -4.93 -3.07 1.86 600, 554, 515 1.93 --- --- 9 (8.5) 682 -1396 -5.00 -3.08 1.92 604, 558, 519 1.94 -4.86, -2.63 2.23 10 (7.3) 536, 1171 -1521 -4.86 -2.97 1.89 602, 556, 518 1.92 --- --- 11 (6.6) 464, 1081 -1651 -4.78 -2.84 1.94 583, 539, 501 2.01 --- --- 12 (3.7) 635, 1183 -1407 -4.95 -3.07 1.88 621, 573, 532 1.88 -4.80, -2.59 2.21 Pentacene (7.5) f 582, 537, 501 2.08 -2.67, -4.96 2.29

18. Computing HOMO & LUMO Energies Blue Cells = Electrochemically Derived Values Green Cells = Computationally Predicted Values Yellow Cells = Mean Absolute Deviations (MAD) All Energies Reported in eV DFTtzv = B3LYP/6-311+G** DFTdzv = B3LYP/6-31G* Pent. HOMO (Expt.) LUMO (Expt.) Gap (Expt.) HOMO (DFTtzv) LUMO (DFTtzv) Gap (DFTtzv) HOMO (DFTdzv) LUMO (DFTdzv) Gap (DFTdzv) 1 -5.17 -3.36 1.81 -5.20 -3.03 2.17 -4.78 -2.7 2.08 2 -5.07 -3.26 1.81 -5.08 -2.89 2.19 -4.69 -2.59 2.10 3 -5.11 -3.42 1.69 -5.08 -3.07 2.01 4 -5.01 -3.00 2.01 -4.93 -2.71 2.22 -4.54 -2.39 2.15 5 -5.00 -3.08 1.92 -4.86 -2.63 2.23 -4.49 -2.33 2.16 6 -4.95 -3.07 1.88 -4.80 -2.59 2.21 -4.43 -2.27 2.16 MAD=0.07 MAD=0.38 MAD=0.32 MAD=0.45 MAD=0.70 MAD=0.24

19. TZV basis set used with B3LYP gives accurate HOMO energies for variety of substituted pentacenes LUMO energy levels are systematically wrong HOMO-LUMO Gaps for DZV B3LYP are closer to experiment by “cancellation of errors” Computing HOMO & LUMO Energies

20. HOMO-LUMO Energy Gaps for [n]Acenes: (n = 2-9) B3LYP/6-31G*

21. Comparing Basis-Sets for [n]Acenes: 6-31G* vs. 6-311+G** B3LYP/6-311+G**//B3LYP/6-31G* B3LYP/6-31G* Green = Closed-Shell Solutions Blue = Open-Shell Solutions Ring # [n] HOMO (eV) LUMO (eV) Gap 2 -6.14 -1.41 4.73 3 -5.57 -2.04 3.53 4 -5.20 -2.46 2.74 5 -4.94 -2.76 2.18 6 -4.74 -2.98 1.76 7 -6.72 -5.31 1.41 8 -6.02 -4.62 1.40 9 -6.72 -5.56 1.16 HOMO LUMO Gap -6.09 -1.40 4.69 -5.53 -2.02 3.51 -5.16 -2.44 2.72 -4.90 -2.74 2.16 -4.71 -2.96 1.75 -4.70 -2.98 1.72 -4.67 -3.03 1.64 -4.62 -3.08 1.54

22. Comparing Basis-Sets for [n]Acenes: 6-31G* vs. 6-311+G** B3LYP/6-31G* Green = Closed-Shell Solutions Blue = Open-Shell Solutions B3LYP/6-311+G**//B3LYP/6-31G* Ring # [n] HOMO (eV) LUMO (eV) Gap 2 -6.14 -1.41 4.73 3 -5.57 -2.04 3.53 4 -5.20 -2.46 2.74 5 -4.94 -2.76 2.18 6 -4.74 -2.98 1.76 7 -4.74 -3.00 1.74 8 -4.70 -3.05 1.65 9 -4.66 -3.11 1.55 HOMO LUMO Gap -6.09 -1.40 4.69 -5.53 -2.02 3.51 -5.16 -2.44 2.72 -4.90 -2.74 2.16 -4.71 -2.96 1.75 -4.70 -2.98 1.72 -4.67 -3.03 1.64 -4.62 -3.08 1.54

23. Approaching “Band-Gap Engineering”: Substituent Effects on Pentacene Derivatives 6,13-Disubstituted Pentacenes: Geometries, Energies and Surfaces Computed from B3LYP/6-311+G** R HOMO LUMO GAP -O - 3.72 4.13 0.41 -NH 2 -4.10 -2.45 1.65 -OH -4.89 -2.78 2.11 -H -4.96 -2.67 2.29 -SCH 3 -5.08 -2.89 2.19 -CN -5.70 -3.76 1.94 -CCH -5.05 -3.12 1.93 -CHO -5.50 -3.66 1.84 -S + (CH 3 ) 2 -10.94 -9.20 1.74 Recall: Hexacene Gap = 1.8 Heptacene Gap = 1.7

24. Exploiting Substituent Effects to Prepare Large, Persistent Acenes

25. C 60 – Pentacene Monoadduct J. Mack and G. P. Miller, Fullerene Science & Technology 1997 , 5 , 607 Fullerene-Acene Chemistry

26. G. P. Miller, J. Briggs, J. Mack, P. A. Lord, M. M. Olmstead, A. L. Balch, Organic Letters 2003 , 5 , 4199 Fullerene-Acene Chemistry

27. 85% Isolated 6,13-Diphenylpentacene Fullerene-Acene Chemistry G. P. Miller and J. Mack, Organic Letters 2000 , 2 , 3979

28. G. P. Miller, J. Mack, and J. Briggs, Organic Letters 2000 , 2 , 3983 Fullerene-Fullerene  Stacking

29. Fullerene-Fullerene  Stacking G. P. Miller, J. Briggs, J. Mack, P. A. Lord, M. M. Olmstead, A. L. Balch, Organic Letters 2003 , 5 , 4199

30.  -  Stacking in Graphite: d = 3.35 Å

31. Spacial Dependence of [60]Fullerene-[60]Fullerene  -  Stacking Interactions 1 1.1 G. P. Miller and J. Briggs, Tetrahedron Letters 2004 , 45 , 477

32. cis,cis- Tris[60]Fullerene Adduct G. P. Miller and J. Briggs, Organic Letters 2003 , 5 , 4203 More Fullerene-Acene Chemistry: Kaur, I. and Miller, G. P., New J. Chem . 2008 , 32 , 459-463. J. E. Rainbolt, G. P. Miller, J. Org. Chem. 2007 , 72 , 3020–3030 J. Athans, J. B. Briggs, W. Jia, G. P. Miller, J. Mat. Chem. 2007 , 17 , 2636–2641 J. Briggs and G. P. Miller, Comptes Rendus Chimie 2006 , 9 , 916

33. Nonacene Cyclodecacene Path Forward: Making Cyclacenes Using Fullerene-Acene Chemistry

34. Path Forward: Making SWNCs Using Cyclacenes

35. SWNCs with Uniform, Tunable Properties: Band-Gap Engineering G. P. Miller, S. Okana, D. Tománek, J. Chem. Phys . 2006 , 124 , 121102

36. Other Nanostructured Carbons

37. Fullerene Nanotubes

38. [60]Fullerene Nanotubes Rauwerdink, K., Liu, J.-F., Kintigh, J. and Miller, G. P., Microscopy Research & Technique , 2007 , 70 , 513-521

39. Functionalized Fullerenes & Fullerene Nanotubes for OPVs

40. Functionalized Fullerenes & Fullerene Nanotubes for OPVs

41. Acknowledgements