LINZ LECTURES

Lecture 1. The Development of Organic Conductors: M t l S d t d S i d tMetals, Superconductors and Semiconductors

Lecture 2A Introduction and Synthesis of ImportantLecture 2A. Introduction and Synthesis of Important Conjugated Polymers

Lecture 2B. Solid State Polymerization

Lecture 3 Fullerene ChemistryLecture 3. Fullerene Chemistry

Lecture 3B. Molecular Engineeringg g

Introduction and Synthesis of Important Conjugated Polymers

Linz, June 10, 2008

General Introduction

Solution PolymerizationSolution Polymerization

OligolyacenesOligolyacenes

Types of Polymers

A A A A A A A A H l-A-A.A-A.A-A-A-A- Homopolymer

-A-B-B-A-B-A-A-B- Random copolymerA B B A B A A B Random copolymer

-A-B-A-B-A-B-A-B- Alternating copolymer

-A-A-A-A-B-B-B-B- Block copolymer

-A-A-A-A-A-A-A-A Graft copolymer||B-B-B-B-B-B

Malcolm P. Stevens “Polymer Chemistry: an Introduction” 3rd Ed. Oxford, 1999

Types of Chains

(a) Linear chain, (b) branched chain, (c) network

Malcolm P. Stevens “Polymer Chemistry: an Introduction” 3rd Ed. Oxford, 1999

Types of Architectures

(h)

(a) Star (b) comb (c) ladder (d) pseudo ladder (e) rotaxane (f) catenane (g) dendrimer (h)

(h)

Malcolm P. Stevens “Polymer Chemistry: an Introduction” 3rd Ed. Oxford, 1999

(a) Star, (b) comb, (c) ladder, (d) pseudo ladder, (e) rotaxane, (f) catenane, (g) dendrimer (h) rigid rod

Malcolm P. Stevens “Polymer Chemistry: an Introduction” 3rd Ed. Oxford, 1999

“For drawn samples, values for the Young's modulus as high as 37 GPa and tensile strength up to 500 MPa have been measured in the machine direction. g pThese properties approach those of many high performance fibers.”

Machado J M ; Masse M A ; Karasz F E Polymer 1989 30 1992Machado, J.M.; Masse, M.A.; Karasz, F.E. Polymer, 1989, 30, 1992

Step Growth or Condensation Polymerization

O O O O

H2N(CH2)6NH2 Cl (CH2)4 Cl HN(H2C)6-HN (CH2)4 n

+

A B -(A-B)-n

Nylon 66

O

H2N(CH2)5 CO2H HN(H2C)5-n

A -(A-)n

M l K l K t PPT PT PP

Nylon 6

Mylar, Kevlar, Kapton, PPT, PT, PPy

Carothers Equation

Malcolm P. Stevens “Polymer Chemistry: an Introduction” 3rd Ed. Oxford, 1999

Chain Growth or Addition Polymerization

Free Radical

Ph OO Ph

O

NN

CNCN

Initiator RΔor hν

RG G

Initiators:Thermal

O O

Ph O

OR H2C CH R CH2CH

R CH2CHG

H2C CHG

R CH2CHG

CH2CHG

+

+

PhPh

O

OH

PhPh

O

RS-SR

Photochemical

R CH2CHG

CH2CHG

H2C CHG

[CH2CH(G)]n

Photochemical

R + HC CH Intractable products

Chain-Growth Polymerization

Malcolm P. Stevens “Polymer Chemistry: an Introduction” 3rd Ed. Oxford, 1999

Ziegler-Natta Polymerization

H2C CHG

Z-N[CH2CH(G)]n2 [ 2 ( )]n

Z-N: Ti(OR)4 AlR3

Z-NHC CH

Z N[CH=CH]n

Anionic, LivingCationic,

Ring Opening Metathesis Polymerization (ROMP)

LnRu=CHPh-(CH=CH)n

R

LnRu=CHPh-(CH=CH-CH=CH-CH=CH-CH=CR)n

R

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.LnRu=CHPh =

Scherman O. A; Rutenberg I. M; Grubbs R. H J. Am. Chem. Soc. 2003, 125, 8515

Organometallic Methods:

Br-Ar-Br (Ar)nCat

Kumada, Yamamoto, Colon

Cat: PdL4, NiL2

Suzuki

Br-Ar-Br (RO)2BAr'-B(OR)2 (Ar-Ar')nCat

+

HeckHeck

Br-Ar-Br Ar' Ar' Arn

Cat

R R

GRIM/Kumada

n

X BrBrGRIMCat

X S

X n

X = S

Sheina, E.E.; Iovu, M.C.; McCullough, R.D. Polym. Prepr. 2005, 46(1), 682

Oxidative (Cationic) Polymerization

R

FeIII

R R

XH

-2H

R

X

X

Fe

X2 2

X

RH

R

2H

R R R

X

X

R

-e(-)

X

R

X FeIII

X

R

X

X

R

X X

X

R

-e(-)

R RR R R R

R R

X

X

R

X

R

X-2H

X

X X

R

XFeIII

X = S, N

R R R R

Oxidative Polymerization

RR RR

Thiophene as a “handle”

X

R

ArX

R

FeIII

X

R

ArX

R

nXX XX n

Polyaniline

NH2

-e(-)

(NH4)2S2O8

NH

x

Ny

e x N

Reductive (Anionic) Polymerization

BrBr O

O Hg( )

O

O

O +e(-)

nBr Br

Utley, J.H.; Gao, Y.; Gruber, J.; Zhang, Y.; Munoz-Escalona, A. Chem Mater. 1995, 5, 1837

Reductive Polymerization

BrBr O

O

O

Hg

+e(-)

O

Br Brn

B B BBr Br

O Hg( )

O

OBr

O

O

O

O

BrHg

BrBr

O +e(-)

nBr

O

nBr

+e(-)

Utley, J.H.; Gao, Y.; Gruber, J.; Zhang, Y.; Munoz-Escalona, A. Chem Mater. 1995, 5, 1837

PPV Synthesis

SMe2SMe2 SMe2

*

Me2S*

*

* = (-) or (•)

SMe2

Δ+ (CH3)2S

( ) or ( )

nn

Processable Polyelectrolyte

Δ

P. M. Lahti, D. A. Modarelli, F. R. Denton, III, R. W. Lenz, F. E. Karasz J. Am. Chem. Soc.

L. Hontis, V. Vrindts, D. Vanderzande, L. Lutsen Macromolecules, Vol. 36, No. 9, 20031988, 110, 7258

The Last Challenge:e ast C a e geLinear Polyacenesy

The Lower Oligoacenes

Polyacenes??o yace es??

AcenesAcenes

Surprisingly, we have discovered that at the

tripletRB3LYP/6-31G(d) level of theory, the wavefunction for as small an oligoacene ashexacene (and all longer oligoacenes) becomes

close shell

hexacene (and all longer oligoacenes) becomesunstable.Re-optimization using the unrestricted

open shellRe-optimization, using the unrestrictedbroken symmetry B3LYP method (UB3LYP),leads to a singlet state with large amounts ofg gdiradical character.

HOMO LUMO G i AHOMO-LUMO Gap in Acenes

8.0

eV)

Cl d h ll

4.0

6.0

MO

gap

(e Closed shellBiradical

0 0

2.0

OM

O-L

UM

0.00 2 4 6 8 10

Acene

H

Plateau at ca. 1.8 eV

Bendikov, M.; Duong, H.M.; Starkey, K.; Houk, K.N.; Carter, E.A.; Wudl, F.; J. Am. Chem. Soc., 2004, 126(24) 7416

A t i l b dAcenes, terminal bond

1.4351.440

1 4101.4151.4201.4251.430

Close shellBiradicalT i l t

1.3901.3951.4001.4051.410 Triplet

0 2 4 6 8 10

Acene

Connection Between Band Theory and Molecular Orbital Theory

According to the Su-Schrieffer-Heeger (SSH) model, the cco d g o e Su Sc e e eege (SS ) ode , eeffective length of a soliton in a σ-system is about 14 carbon atoms.

This is in agreement with our calculations, predicting diradical character in oligoacenes, and thus, hexacene-gheptacene have already enough σ -length (two 13-15 carbon atom chains, respectively) to produce two oligoacetylene

litsolitons.

The instabilities found for heptacene-octacene appear toThe instabilities found for heptacene-octacene appear to indicate that they are the “connector” between band theory and molecular orbital theory.y

Heeger, A. J.; Kivelson, S.; Schrieffer, J. R.; Su, W.-P. Rev. Mod. Phys. 1988, 60, 781.

Spin Densityp y

Bendikov, M.; Duong, H.M.; Starkey, K.; Houk, K.N.; Carter, E.A.; Wudl, F.; J. Am. Chem. Soc., 2004, 126(24) 7416

Summary

In contrast to the common view that acenes are closed shellsystems or have triplet ground states, we predict that largeroligoacenes possess an open-shell singlet ground state,where the triplet lies above singlet.

We have shown computationally that oligoacenes andprobably a variety of polyacene derivatives and analoguesp y y p y gshould exhibit a nonzero band gap.

It should be possible to prepare a linear polyacene, providedit is formed as a solid, with minimum lifetime in solution. Inanalogy with oligoenes vs polyacetyleneanalogy with oligoenes vs polyacetylene.

EXPERIMENTAL RESULTS

Matrix Isolated Heptacene

R. Mondal, B. K. Shah, D. C. Neckers J. Am. Chem. Soc. 2006, 128, 9612

R. Mondal, B. K. Shah, D. C. Neckers J. Am. Chem. Soc. 2006, 128, 9612

Isolable But Very Short-Lived Substituted Heptacene

Marcia M. Payne, Sean R. Parkin, and John E. Anthony 2005, 127, 8028

Marcia M. Payne, Sean R. Parkin, and John E. Anthony 2005, 127, 8028

Marcia M. Payne, Sean R. Parkin, and John E. Anthony 2005, 127, 8028

TIPS ACETYLENE TETRAARYLHEPTACENE ISOLABLE AND RELATIVELY STABLE

Si(iPr) SiSi(iP )

Br

B

OBr

Br

Si(iPr)3 SiSi(iPr)3

PhPh

O Oa b c

Ph Ph

BrO

Br

Si(iPr)3 SiSi(iPr)3

PhPhPh Ph

a, (i) TipsCCLi (ii) SnCl2; b, LTMP/DPIBF; c, Zn/AcOH

D. Chun, F. Wudl, unpublished

CRYSTAL STRUCTURE OF BIS(TIPSTHYNYL) TETRAPHENYL HEPTACENE

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

D. Chun, F. Wudl, unpublished

Electronic Spectroscopy

PHOTOINDUCED OXYGEN DEGRADATION

Si SiSi

PhPh

Si

PhPh O

OO2

Si

PhPh

Si

PhPh

Ohν

LIMITED CYCLIC VOLTAMMETRY

Photoinduced Charge Generation

H. F. Bettinger, R. Mondalb and D. C. Neckers Chem. Commun., 2007, 5209