Acenes, Fullerenes and Carbon Nanotubes

Glen P. Miller Department of Chemistry and Materials Science Program

University of New Hampshire

Columbia University September 17, 2008

Acenes: Polycyclic aromatic hydrocarbons composed of

linearly annelated benzene rings

(Clar, E. Polycyclic Hydrocarbons; Academic Press Inc: London, 1964; Vol. 1, pp 4-5)

Acene Applications

Acene Degradation:Competing Photo-Oxidation Mechanisms

Substituent Effects on Acene Longevity

Kinetics of Photo-Oxidation

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

Kinetics of Photo-Oxidation

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

Evidence for Singlet Oxygen Chemistry

Lessons Learned: Location, Location, Location

Lessons Learned:Steric Resistance is Important

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

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

Steric & Electronic Effects Combined

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

Arylthio and Alkylthio Substituted Pentacenes are the Big Winners

Thin-Film Characteristics

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

HOMO & LUMO Energies

HOMO & LUMO Energies and Gapspentacenederivative

(t1/2)

E1/2 [O]a

(mV)E1/2

[red]a

(mV)

EHOMO

(eV)ELUMO

(eV)Eg,EChem

(eV)low energymax (nm)

Eg,optical (eV)c

EHOMO,DFT, ELUMO,DFT

(eV)

Eg,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

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

Blue Cells = Electrochemically Derived ValuesGreen Cells = Computationally Predicted ValuesYellow Cells = Mean Absolute Deviations (MAD)

All Energies Reported in eV DFTtzv = B3LYP/6-311+G**DFTdzv = B3LYP/6-31G*

Computing HOMO & LUMO Energies

• 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

HOMO-LUMO Energy Gaps for [n]Acenes: (n = 2-9) 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 -6.72 -5.31 1.41

8 -6.02 -4.62 1.40

9 -6.72 -5.56 1.16

B3LYP/6-311+G**//B3LYP/6-31G*

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

B3LYP/6-31G*

Green = Closed-Shell Solutions Blue = Open-Shell Solutions

Comparing Basis-Sets for [n]Acenes: 6-31G* vs. 6-311+G**

n

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

B3LYP/6-31G*

Green = Closed-Shell Solutions Blue = Open-Shell Solutions

n

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

B3LYP/6-311+G**//B3LYP/6-31G*

Comparing Basis-Sets for [n]Acenes: 6-31G* vs. 6-311+G**

Approaching “Band-Gap Engineering”: Substituent Effects on Pentacene Derivatives

R

R

R HOMO LUMO GAP-O- 3.72 4.13 0.41

-NH2 -4.10 -2.45 1.65

-OH -4.89 -2.78 2.11

-H -4.96 -2.67 2.29

-SCH3 -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+(CH3)2 -10.94 -9.20 1.74

6,13-Disubstituted Pentacenes:Geometries, Energies and Surfaces Computed from B3LYP/6-311+G**

Recall:Hexacene Gap = 1.8Heptacene Gap = 1.7

Exploiting Substituent Effects to Prepare Large, Persistent Acenes

C60

C60 – Pentacene Monoadduct

J. Mack and G. P. Miller, Fullerene Science & Technology 1997, 5, 607

Fullerene-Acene Chemistry

G. P. Miller, J. Briggs, J. Mack, P. A. Lord, M. M. Olmstead, A. L. Balch, Organic Letters 2003, 5, 4199

Fullerene-Acene Chemistry

C60

85% Isolated6,13-Diphenylpentacene

Fullerene-Acene Chemistry

G. P. Miller and J. Mack, Organic Letters 2000, 2, 3979

3.2 Å

1.55 Å2.26 Å

123.9o154.5o

G. P. Miller, J. Mack, and J. Briggs, Organic Letters 2000, 2, 3983

Fullerene-Fullerene Stacking

Fullerene-Fullerene Stacking

G. P. Miller, J. Briggs, J. Mack, P. A. Lord, M. M. Olmstead, A. L. Balch, Organic Letters 2003, 5, 4199

-Stacking in Graphite: d = 3.35 Å

Spacial Dependence of [60]Fullerene-[60]Fullerene -Stacking Interactions

O

O

O

O

+

O

O

C60

1

1.1

G. P. Miller and J. Briggs, Tetrahedron Letters 2004, 45, 477

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, 3020–3030A.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

O

O

Ph

Ph

Ph

Ph

O

Ph

Ph

O

O

+

Ph

Ph

Ph

Ph

DDQ

C60

HI

AcOH

BrBr

Ph

Ph

Ph

Ph

Ph

Ph

Ph

Ph

Ph

Ph

CH2Br

CH2Br

Nonacene

Cyclodecacene

DDQC60

N2dark

AlCl3 /N2Pd/C

Path Forward: Making Cyclacenes Using Fullerene-Acene Chemistry

Path Forward: Making SWNCs Using Cyclacenes

SWNCs with Uniform, Tunable Properties: Band-Gap Engineering

G. P. Miller, S. Okana, D. Tománek, J. Chem. Phys. 2006, 124, 121102

Other Nanostructured

Carbons

Fullerene Nanotubes

[60]Fullerene Nanotubes

Rauwerdink, K., Liu, J.-F., Kintigh, J. and Miller, G. P., Microscopy Research & Technique, 2007, 70, 513-521

Functionalized Fullerenes & Fullerene Nanotubes for OPVs

Functionalized Fullerenes & Fullerene Nanotubes for OPVs

Acknowledgements