15.01.04 lcnf03p03aw.ppt - part 3 1

Part 3: Functional π-Systems

Outline

Ø Introduction

Ø Organic conducting molecules and polymers

Ø Fullerenes and nanotubes

Ø Flavins, DNA Photolyase

Ø Organic Light Emitting Diodes (OLED)

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Books and Articles

» J. Olmsted, III, G. M. Williams, Chemistry, 3rd ed., JohnWiley & Sons, New York, 2002.

» J.-M. Lehn, Supramolecular Chemistry Concepts andPerspectives, VCH, Weinheim, 1995.

» Der Weg zu einer neuen Materialklasse: Elektrischleitfähige Kunststoffe: M. Rehahn, Chemie in unserer Zeit2003, 37, 18-30.

» A. Hirsch The Chemistry of the Fullerenes; Thieme,Stuttgart, 1994.

» Elektrolumineszierende konjugierte Polymere - Polymereerstrahlen in neuem Licht: A. Kraft, A. C. Grimsdale, A.B. Holmes, Angew. Chem. 1998, 110, 416-443.

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The scaling of matter

» A. J. Bard, Integrated Chemical Systems - AChemical Approach to Nanotechnology, Wiley-Interscience, New York, 1994.

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Functional molecular and supramolecular devices

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Conductivity(S cm-1) of

organic andinorganicmaterials

pf

» A. G. MacDiarmid, Angew. Chem. 2001, 113, 2649-2659.

σσ/[S•cm-1] = n⋅⋅e⋅µ⋅µ σσ: conductivity

µ: mobilitye: electron charge

n: number of chargecarriers

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Band structure of lithium clusters Lin (Olmsted/Williams)

pf

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Conducting metals adjust their band structure to externalpotential – band bending (Olmsted/Williams)

pf

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pf

A semiconductor becomes a conductor by heating or byabsorption of light (Olmsted/Williams)

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Lead and diamond have different band gaps (Olmsted/Williams)

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Electrically conducting materials: molecularinteraction and band structure

Electronic energy level:top: a dimer formed of twomonomers

bottom: large assembly ofisolated molecular units(atoms) - band structure

» A. J. Bard, 'Integrated ChemicalSystems - A Chemical Approach toNanotechnology', Wiley-Interscience,1994.

pf_lcnf

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Charge-Transfer and Conductivity

pf/lcnf

CN

CNNC

NCS

S S

S S

S S

SS

S S

S

Tetracyanoquino-dimethane

(TCNQ)electron acceptor

Tetrathiafulvalene(TTF)

electron donor

BEDT-TTF

Ø BEDT-TTF: Bis(ethylenedithio)tetrathiafulvalene, beyond 4 Ksuperconductive on doping: (BEDT-TTF)2Cu(CF3)4 (J. Chem.Soc., Chem. Comm. 1994, 1599)

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Synthesis of TTF

pf/lcnf

EtO2C CO2EtS

SS

S

S S

S

(TTF)+

first step

Ø An Improved Synthesis of Tetrathiafulvalene, L. R.Melby, H. D. Hartzler, W. A. Sheppard, J. Org. Chem.1974, 36, 2456-2458.

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Synthesis of TCNQ

pf/lcnf

O

O

NC

NC

CN

CN

CH2(CN)2

TiCl4pyridineCH2Cl2

r.t.24 h

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Conducting charge-transfer systems

pf/lcnf

» F. Wudl, Acc. Chem. Res. 1984, 17, 227-232., 99, 1787-1799.

» M. Pope, C. E. Swenberg ElectronicProcesses in Organic Crystals andPolymers, Second Edition; Oxford UnivPress: Oxford, UK, 1999.

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About conducting polymers

pf

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π-Conjugated polymers: semiconducting materials

n

n

Polyacetylene (PA)» H. Shirakawa, Angew. Chem. , Int. Ed. 2001,

40, 2575.

Polyphenylene (PP)» A. J. Berresheim, M. Müller, and K. Müllen,

Chem. Rev., 1999, 99, 1747.

Hn

Polyphenylenevinylene (PPV)» A. Kraft, A. C. Grimsdale, and A. B. Holmes,

Angew. Chem., 1998, 110, 416.

pf

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π-Conjugated polymers: semiconducting materials

Polythiophene (PT)» J. Roncali, Chem. Rev. 1992, 92, 711-

738.

Sn

Polyazulene (PAZ)» F. X. Redl, O. Koethe, K. Roeckl, W.

Bauer, J. Daub, Macromol. Chem.Phys. 2000, 201, 2091-2100.

n

Polyaniline (PANI)

» A. G. MacDiarmid, Angew.Chem. 2001, 113, 2649-2659.

N

H

N

H

N

H

NH

pf

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Metathesis based ring-opening-polymerisation

. » Acc. Chem. Res. 1990, 23, 158-165.

CF3CF3CF3CF3

R1

R2

R3

R1

R2

R3

R2

R1R3

CF3CF3

cat

n n

∆∆

cat: (RO-)2W(=N-Ar)(=CHR)

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Ring-opening-polymerisation

.pf

» J. Am. Chem. Soc. 1989, 111, 7989.

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Ring-opening-polymerisation - References

.pf

» Olefin metathesis and beyond, A. Fürstner, Angew. Chem. Int. Ed.2000, 39, 3012-3043.

» K. J. Ivin, J. C. Mol, Olefin Metathesis and Metathesis Polymerization,Academic Press, San Diego, 2003.

» Die Olefinmetathese - neue Katalysatoren vergrößern dasAnwendungspotential, M. Schuster, S. Blechert, Chemie in unsererZeit 2001, 35, 24-29.

» Living ring-opening metathesis polymerization catalyzed by well-characterized transition-metal alkylidene complexes, R. R. Schrock,Acc. Chem. Res. 1990, 23, 158-165.

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Suzuki reaction - mechanism

1: oxidative addition2: transmetalation3: reductive elimination

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Synthesis of poly(p-phenylene) – Suzuki route

R

R

BrBr

R

R

* *n

R

R

B(OH)2Br

1. n-BuLi (1 mol)2. B(OCH3)3

3. HCl

Pd(OAc)2, PPh3

Na2CO3

» Coupling Method, see: A. Suzuki, Cross-coupling Reactions of OrganoboronCompounds with Organic Halides. In Metal-catalyzed Cross-coupling reactions;Diederich, F.; Stang, P. J. Eds.; Wiley-VCH: Weinheim, 1998.

pf

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Synthesis of poly(p-phenylene) – Bergman cyclization

R

* *n

R

RR

RR heat

n n

» Tetrahedron 1997, 53, 15515-15534.pf

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Calicheamicin - action based on Bergmancyclization

» Angew. Chem. 1991, 103, 1453-1481.

tbb

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Calicheamicin - chemistry of action

tbb

» Angew. Chem. 1991,103, 1453-1481.

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Synthetic route to polyphenylenevinylene (PPV)

CH2

CH2

R

R

SS

CH3

CH3CH3

CH3

CH

R

R

CH2S

CH3 CH3 n

R

R

**n

Cl Cl Cl

+ +

+

NaOH

H2O

300°C

-(CH3)2S, HCl

pf

» Electronic Materials: The Oligomer Approach; Muellen, K.; Wegner,G. Eds.; Wiley-VCH: Weinheim, 1998; 1.

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Synthesis of polyphenylenevinylene (PPV):Metathesis reaction

» Angew. Chem. 1997, 109, 2125; K. Müllen, G. Wegner, ‘ElectronicMaterials: The Oligomer Approach’, Wiley-VCH, Weinheim, 1998

pf

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Cyclic voltammetry

» Angew. Chem. 1984, 96, 823-840.mp

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Cyclic voltammetry under diffusion controlled conditions (left)and surface-immobilized conditions such as a conductingpolymer film (right)

mp

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Azulene/polyazulene: electrochemicalpolymerisation and dotation

» A. Mirlach. Dissertation, Universität Regensburg 1993» A. Mirlach, M. Feuerer, J. Daub, Adv. Mater. 1993, 5, 450-453. pap

HH n

dotated polyazuleneconducting material

radical cation/polaron

+

n

anodicoxidation

dotationby

electrochemicaloxidation

azulenemonomer

polyazulenenonconducting material

insulator

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Azulene/polyazulene-cyclic voltammetry

pap

left side: CV of the initial process of electropolymerisationright side: formation of a conducting film on the electrode

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Polyaniline – general formula

» A. G. MacDiarmid, Angew. Chem. 2001, 113, 2649-2659. pf

N

H

N

H

N N

X

( ) ( )y 1-y

y: 1 ⋅⋅⋅⋅⋅ 0.5 ⋅⋅⋅⋅⋅ 0

(1-y) = 0: leucoemeraldine(1-y) = 1: pernigraniline(1-y) = 0.5: emeraldine

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Polyaniline – conducting and nonconducting forms

pf

N

H

N

H

N

H

NH

N

H

N

H

N N

N N N N

N

H

N

H

N

H

NH

++

completely reduced form(leucoemeraldine)

semioxidized form(emeraldine)

oxidized form(pernigraniline)

conducting statemade by oxidationof leucoemeraldineor protonation of

emeraldine

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Properties and applications of conducting polymers

pf

Ø nonlinear optical responceØ semiconducting propertiesØ conducting transparent plasticsØ thin-film field-effect transistorsØ light-emitting diodesØ solid-state lasersØ photovoltaic devicesØ chemical sensors

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Allotropic forms of carbon

diamond graphite fullerene

l / cnf

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A high symmetric molecule – icosahedral symmetry (Ih)

C60 fullerene

l / cnf

Ø The Beauty of Symmetry: A. Müller, Science 2003, 300, 749-750.

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Platonic Symmetry

l / cnf

» Platonische Kohlenwasserstoffe: W. Grahn, Chemie in unserer Zeit1981, 15, 52-61.

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Nanotubes

» ChemPhysChem 2001, 2, 78-105; Chem. Rev. 1999, 99, 1787-1799. lcnf/sfg

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gff_lcnf

Isoalloxazine a heterocycle with great importance in Nature

∗ nomenclature of flavin: 7,8-dimethylbenzo[g]pteridine-2,4(3H,10H)-dione

∗ Riboflavin, Vitamin B2

∗ FMN: riboflavin-5‘-phosphate (D-ribityl unit)∗ major absorption bands of flavin in its oxidized form: (1)446,

(2)375, (3)265, 220 nm (polarization according to the right sideformula)

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gff_lcnf

Flavin: absorption and emission spectra

∗ color of flavin: yellow∗ color of fluorescence: bright

yellow, in aqueous solution,Φf 0.26, pH 7

∗ phosphorescence ( λ ~ 610nm, < 150K, orange-red, ΦP

0.0012)

P. F. Heelis, Chem. Soc. Rev. 1982, 11, 15-39;P. F. Heelis. The Photochemistry of Flavins. In Chemistry andBiochemistry of Flavoenzymes; Müller, F. Ed.; CRC: Boca Raton,1991; Vol. 1; pp. 171-193.

fluorescence

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Ribbon diagram of DNA photolyase of Eschericia colignl_lcnf

Science 1995, 268,1866-1872.

αα/ββ domain: whiteMTHF: light grayhelical domain: goldFAD: greenAMP: red

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gnl_lcnf

Photolyase dependentrepair of DNA lesion

» Science 1999, 284, 760-765.» Eur. J. Org. Chem. 1998,

1245-1258.

antenna

excitation energy transfer

electron transfer:bond breaking upon reduction

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fds_lcnf

Organic light emitting diodes: references

» Organic electroluminescent diodes: C. W. Tang, S. A. VanSlyke, Appl. Phys.Lett. 1987, 51, 913-915.

» Light-emitting diodes based on conjugated polymers: J. H. Burroughes, D. D.C. Bradley, A. R. Brown, R. N. Marks, K. MacKay, R. H. Friend, P. L. Burn, A.B. Holmes, Nature 1990, 347, 539-541.

» Efficient Two Layer LEDs on a Polymer Blend Basis: J. Pommerehne, H.Vestweber, W. Guss, R. F. Mahrt, H. Bässler, M. Porsch, J. Daub, Adv.Mater. 1995, 7, 551-554.

» Electroluminescence with Organic Compounds: J. Salbeck, Ber. Bunsenges.Phys. Chem. 1996, 100, 1667-1677.

» Elektrolumineszierende konjugierte Polymere - Polymere erstrahlen inneuem Licht: A. Kraft, A. C. Grimsdale, A. B. Holmes, Angew. Chem. 1998,110, 416-443.

» The electroluminescence of organic materials: U. Mitschke, P. Baeuerle, J.Mater. Chem. 2000, 10, 1471-1507.

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fl_lcnf

Organic light emitting diodes (LED): basic processes

» Angew. Chem. 1998, 110,416-443.

a: photoluminescence

b: electroluminescence

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fds_lcnf

Organic light emitting diodes (LED): polymer blend basis

» Appl. Phys. Lett. 1987,51, 913

» Adv. Mater. 1995, 7,551-554.

» Bunsenges. Phys. Chem.1996, 100, 1667-1677.

Polymer- LED‘s use polymers suchas PPV as electroluminescentmaterials: Nature 1990, 347, 539-541.

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fds_lcnf

Organic light emitting diodes (LED): polymer-LED

» Nature 1990, 347, 539-541; Angew. Chem. 1998, 110, 416-443.