Polycyclic Aromatic Hydrocarbons(PAH)

Tobe LaboAyumi Yoshizaki

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Contents＊ Introduction - Carbon-carbon Bond - Planar Molecule

＊ PAH - What is PAH ? - Application of PAH

＊ History - Successive Synthesis Method

＊ New Synthesis Method - Recent Research

＊ My Project

＊ Summary 2

Carbon-carbon Bond

GraphiteDiamond

sp2sp3 π-electron

Because the carbon atom has four unpaired electrons, four bonds are necessary.

Diamond and Graphite, the isotopes of the carbon, are described below.

van der Waals' force

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Planar MoleculeDiamond Graphite

Color Colorless Black

Band Structure

Conductivity × ○

Conduction Band

Valence Band

Wide

Six sp2 Carbons + Six Hydrogens

Benzene 4

What is PAH ?

PhenanthreneAnthracene

＊ Polycyclic Aromatic Hydrocarbons (PAH)→Compound that one or more aromatic rings are condensed

Naphthalene Azulene

Perylene

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Semiconductor

The display is printed on clothes.

The curtain and the screen become the televisions.

Inorganic Semiconductor

Organic Semiconductor

Material Si, Ge PAH

Property Hard, Heavy, Expensive Flexible, Light, Cheap

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Application of PAH

Pentacene

Pentacene is an organic compound that first exceeds the amorphous silicon level (Driving level of liquid crystal display) .

Amorphous Silicon Level Career Mobility > 1.0 cm2/Vs

Pentacene Level Career Mobility > 1.5 cm2/Vs

It is historical event of science and technology that organic semiconductor replaces inorganic semiconductor.

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Traditional Synthesis Method＊ Friedel-Crafts Reaction

＊ Diels-Alder Reaction

COOH

HOOC

O

O

AlCl3 Zn

Postovoslii, I. et al. Zh. Obsch. Khim. 1937, 7, 2919-2924.

Clar, E. et al. J. Chem. Soc. 1957, 4616-4619.

Perylene Coronene

Perylene

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Recent Synthesis Method

Hexa-peri-hexabenzocoronene

Dehydro-genation

Diels-AlderReaction

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New Synthesis Method

Hauptmann, H. et al. Tetrahedron Lett. 1980, 21, 897-898.

Non-cyclic Structure → Low Selectivity, Low Yield

Cyclic Structure → Transannular Cyclization 　　　　　　　　　　　　　　　　　　 → Tandem Cyclization

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[N]annulene

[18]annuleneBenzene[6]annulene

Cyclobutadiene[4]annulene

Dehydrobenzo -[14]annulene

Dehydrobenzo-[8]annulene

Dehydrobenzo -[12]annulene

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Recent Research

Otera, J. et al. Chem. Lett. 2008, 37, 1296-1297.

①Nucleophile 　

②Charge Transfer

③Transannular 　Cyclization

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My Project

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Summary＊ Polycyclic Aromatic Hydrocarbons (PAH), Compound that one

or more aromatic rings are condensed, are expected that replaces inorganic semiconductor.

＊ Traditionally, PAHs have been synthesized in stepwise synthesis methods which construct a ring one-by-one.

＊ In recent years, on the other hand, plural rings of PAHs are efficiently constructed.

＊ Recently, we have developed new single-step synthetic methods with high efficiency by tandem cyclization reaction of integrated acetylene.

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