Polycyclic Aromatic Hydrocarbons (PAH) Tobe Labo Ayumi Yoshizaki 1 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 Because the carbon atom has four unpaired electrons, four bonds are necessary. Diamond and Graphite, the isotopes of the carbon, are described below. sp3 sp2 π-electron van der Waals' force Diamond Graphite 3 Planar Molecule Color Diamond Graphite Colorless Black Conduction Band Band Structure Wide Valence Band Conductivity × + Six Hydrogens Six sp2 Carbons ○ Benzene 4 What is PAH ? ＊Polycyclic Aromatic Hydrocarbons (PAH) →Compound that one or more aromatic rings are condensed Naphthalene Anthracene Phenanthrene Azulene Perylene 5 Semiconductor Material Inorganic Semiconductor Organic Semiconductor Si, Ge PAH Property Hard, Heavy, Expensive The display is printed on clothes. Flexible, Light, Cheap The curtain and the screen become the televisions. 6 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. 7 Traditional Synthesis Method ＊Friedel-Crafts Reaction Perylene Postovoslii, I. et al. Zh. Obsch. Khim. 1937, 7, 2919-2924. ＊Diels-Alder Reaction Perylene Coronene Clar, E. et al. J. Chem. Soc. 1957, 4616-4619. 8 Recent Synthesis Method Hexa-peri-hexabenzocoronene Diels-Alder Reaction Dehydrogenation 9 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 10 [N]annulene Cyclobutadiene [4]annulene Dehydrobenzo[8]annulene Benzene [6]annulene Dehydrobenzo [14]annulene [18]annulene Dehydrobenzo [12]annulene 11 ①Nucleophile Recent Research ②Charge Transfer ③Transannular Cyclization Otera, J. et al. Chem. Lett. 2008, 37, 1296-1297. 12 My Project 13 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. 14
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