Oligoacenes are of interest as organic p-type semiconductors for use in electronic devices, but their use as n-type semiconductors is limited. N-Heteroacenes have been investigated as oligoacene-based n-type semiconductors due to their enhanced electron affinity. Herein, we report the synthesis, X-ray crystal structures, electrochemical, and field-effect transistor properties of TANC and BTANC.

Artificial conductors constructed from molecular building blocks can replicate unique low-dimensional electron-transport phenomena depending on the nature of their molecular components.[1] For example, Cu(DCNQI) 2 (DCNQI = N,N'-dicyanoquinodiimine) systems formed from coordination polymers containing alternating 3D linkages between Cu ion donors and organic DCNQI acceptors exhibit an interesting metal-insulator (M-I) transition under high pressure. This behavior is due to the interaction between the localized 3d-electron bands of the Cu ions and the p-electron conductive bands of DCNQI.[2] Therefore, the appropriate combination of donors and acceptors as molecular building blocks, which often form an electron-conducting solid, plays an important role in determining the electron-transport character of a molecular crystal.Molecules that form high-conductivity molecular solids, particularly organic acceptors, have been limited thus far to cyanoquinoid derivatives such as TCNQ [3] and DCNQI [4] and the metal complex [M(dmit) 2 ] (dmit = 1,3-dithiole-2-thioxo-4,5-dithiolato).[5] Molecular conductors with various electrondonor frameworks based on heterocyclic structures containing a chalcogen atom such as tetrathiafulvalene (TTF) [6] and tetramethyltetraselenofulvalene (TMTSF) [7] have also been realized, and studies are underway to discover a fundamental molecule with a stable electron-accepting framework to form molecular conductors with a desired transport behavior. Herein, we report a modifiable electron acceptor with 5,6,11,12-tetraazanaphthacene (TANC) as a new fundamental framework and the preparation of a high-conductivity crystal (1) from Cu I -TANC coordination polymers.TANC was prepared by modifying a synthetic procedure first reported by Hill.[8] The yellow precipitate obtained from the thermal condensation between o-phenylenediamine and oxamide contains 2,2'-bibenzimidazole and 5,11-dihydro-5,6,11,12-tetraazanaphthacene (FFV) in a 3:1 ratio. This mixture was oxidized with PbO 2 in MeCN to give brown crystals of TANC in 20 % yield. The cyclic voltammogram of TANC in MeCN exhibits two reversible one-step, oneelectron waves in the reverse sweep (E 1 1/2 = À0.20 and E 2 1/2 = À0.88 V vs Ag/AgCl), which means that TANC is a weaker electron acceptor than organic acceptors such as TCNQ and DCNQI that form high-conductivity materials. [9] Unfortunately, TANC cannot be employed as an organic semiconductor with n-type characteristics.The TANC radical anion can be isolated from an electron disproportionate reaction between FFV and TANC under basic conditions. This compound was obtained as a green precipitate under anaerobic conditions, which immediately turns gray upon exposure to air. The ESR spectrum of the precipitate exhibits a typical anisotropic peak (g ? = 2.011 and g k = 2.0091) that stabilizes at room temperature (see the Supporting Information).The high-conductivity crystal 1, which has the composition [{Cu(TANC)}F 0.5 ] n , was obtained from the reaction between TANC and [Cu(MeCN) 4 ]BF 4 in MeOH/MeCN in t...

Artificial conductors constructed from molecular building blocks can replicate unique low-dimensional electron-transport phenomena depending on the nature of their molecular components.[1] For example, Cu(DCNQI) 2 (DCNQI = N,N'-dicyanoquinodiimine) systems formed from coordination polymers containing alternating 3D linkages between Cu ion donors and organic DCNQI acceptors exhibit an interesting metal-insulator (M-I) transition under high pressure. This behavior is due to the interaction between the localized 3d-electron bands of the Cu ions and the p-electron conductive bands of DCNQI.[2] Therefore, the appropriate combination of donors and acceptors as molecular building blocks, which often form an electron-conducting solid, plays an important role in determining the electron-transport character of a molecular crystal.Molecules that form high-conductivity molecular solids, particularly organic acceptors, have been limited thus far to cyanoquinoid derivatives such as TCNQ [3] and DCNQI [4] and the metal complex [M(dmit) 2 ] (dmit = 1,3-dithiole-2-thioxo-4,5-dithiolato).[5] Molecular conductors with various electrondonor frameworks based on heterocyclic structures containing a chalcogen atom such as tetrathiafulvalene (TTF) [6] and tetramethyltetraselenofulvalene (TMTSF) [7] have also been realized, and studies are underway to discover a fundamental molecule with a stable electron-accepting framework to form molecular conductors with a desired transport behavior. Herein, we report a modifiable electron acceptor with 5,6,11,12-tetraazanaphthacene (TANC) as a new fundamental framework and the preparation of a high-conductivity crystal (1) from Cu I -TANC coordination polymers.TANC was prepared by modifying a synthetic procedure first reported by Hill.[8] The yellow precipitate obtained from the thermal condensation between o-phenylenediamine and oxamide contains 2,2'-bibenzimidazole and 5,11-dihydro-5,6,11,12-tetraazanaphthacene (FFV) in a 3:1 ratio. This mixture was oxidized with PbO 2 in MeCN to give brown crystals of TANC in 20 % yield. The cyclic voltammogram of TANC in MeCN exhibits two reversible one-step, oneelectron waves in the reverse sweep (E 1 1/2 = À0.20 and E 2 1/2 = À0.88 V vs Ag/AgCl), which means that TANC is a weaker electron acceptor than organic acceptors such as TCNQ and DCNQI that form high-conductivity materials. [9] Unfortunately, TANC cannot be employed as an organic semiconductor with n-type characteristics.The TANC radical anion can be isolated from an electron disproportionate reaction between FFV and TANC under basic conditions. This compound was obtained as a green precipitate under anaerobic conditions, which immediately turns gray upon exposure to air. The ESR spectrum of the precipitate exhibits a typical anisotropic peak (g ? = 2.011 and g k = 2.0091) that stabilizes at room temperature (see the Supporting Information).The high-conductivity crystal 1, which has the composition [{Cu(TANC)}F 0.5 ] n , was obtained from the reaction between TANC and [Cu(MeCN) 4 ]BF 4 in MeOH/MeCN in t...

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A Short and Stereoselective Synthesis of Highly Substituted Cyclopropanes from α,β-Unsaturated Carbonyl Compounds with Dichloromethyl p-Tolyl Sulfoxide. -(MIYAGAWA, T.; TATENUMA, T.; TADOKORO, M.; SATOH*, T.; Tetrahedron 64 (2008) 22, 5279-5284; Dep. Chem., Fac. Sci., Sci. Univ. Tokyo, Shinjuku, Tokyo 162, Japan; Eng.) -Klein 43-070