N‐Heteroacenes

Bunz, Uwe H. F.

doi:10.1002/chem.200900990

Cited by 241 publications

(114 citation statements)

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“…[1a,5] To realize good performing p-n junctions or complementary logic circuits, it is necessary to develop high-performance n-type materials. [6] Theoretical calculations have already predicted that N-substituted oligoacenes would be promising n-type materials due to their large electron affinities. [7] Since then, longer oligoazaacenes with enhanced electron affinities have been widely observed as n-type semiconductors, and higher electron mobility of up to 3.3 cm 2 V À1 s À1 in azapentacene has been achieved through organic thin-film transistors.…”

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confidence: 99%

Understanding the Electronic Structure of Larger Azaacenes through DFT Calculations

Gao

Zhang

2014

Israel Journal of Chemistry

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Although azapentacenes have been widely demonstrated as promising candidates for n‐type organic semiconductor devices, the exploration of larger azaacenes is still a challenge. In particular, theoretical studies on the electronic structures of larger azaacenes and the influence of N substitution on the ground states are still rare. Herein, we reported our investigation on the electronic ground‐state characters of larger azaacenes through density functional theory (DFT) calculations. Our results indicated that larger azaacenes (fused aromatic rings larger than 6) would show open‐shell singlet biradical characters and the introduction of more N atoms into the backbone of large acenes could favor their closed‐shell ground states. Interestingly, azahexacenes with three or more N atoms (compounds N64–N68) and azaheptacenes (compound N74) with fourteen N atoms displayed closed‐shell singlet ground states compared with the open‐shell singlet diradical ground states for larger acenes. Our theoretical studies may guide the design and synthesis of larger azaacenes, which are the promising n‐type organic semiconducting materials.

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Understanding the Electronic Structure of Larger Azaacenes through DFT Calculations

Gao

Zhang

2014

Israel Journal of Chemistry

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“…To realize the full potential of acenes and heteroacenes, it is essential to expand the scope of materials available. Figure 1a shows recent and historical members in the series of pentacenes 13,14 . Chlorinated pentacenes such as 6 were processed into ambipolar transistors.…”

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Effects of electronegative substitution on the optical and electronic properties of acenes and diazaacenes

et al. 2010

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Large acenes, particularly pentacenes, are important in organic electronics applications such as thin-film transistors. Derivatives where CH units are substituted by sp 2 nitrogen atoms are rare but of potential interest as charge-transport materials. In this article, we show that pyrazine units embedded in tetracenes and pentacenes allow for additional electronegative substituents to induce unexpected redshifts in the optical transitions of diazaacenes. The presence of the pyrazine group is critical for this effect. The decrease in transition energy in the halogenated diazaacenes is due to a disproportionate lack of stabilization of the Homo on halogen substitution. The effect results from the unsymmetrical distribution of the Homo, which shows decreased orbital coefficients on the ring bearing chlorine substituents. The more strongly electron-accepting cyano group is predicted to shift the transitions of diazaacenes even further to the red. Electronegative substitution impacts the electronic properties of diazaacenes to a much greater degree than expected.

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“…More recently, nitrogen containing heteroacenes have emerged as materials that have properties complementary to typical acenes. [13] N-Heteroacenes have been investigated as electron-transport materials, whereas all-carbon acenes have seen more use as hole transport layers. Furthermore, incorporation of electronegative atoms within the acene core results in p-deficient aromatic heterocycles, which makes them more resistant to undesired oxidation.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, incorporation of electronegative atoms within the acene core results in p-deficient aromatic heterocycles, which makes them more resistant to undesired oxidation. [13] With the increased electronic materials interest in larger acenes and PAHs, our focus has now turned to applying the pericyclic/coarctate cyclizations for the synthesis of larger aromatic heterocycles. Herein we describe our first steps toward this goal, namely the preparation of naphthalene-based azo-ene-yne precursors and their conversion into a variety of benzocinnolines and benzoisoindazoles.…”

Section: Introductionmentioning

confidence: 99%

Coarctate versus Pericyclic Reactivity in Naphthalene‐Fused Azo–Ene–Ynes: Synthesis of Benzocinnolines and Benzoisoindazoles

McClintock

Zakharov

Herges

et al. 2011

Chemistry A European J

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The cyclization reactions of naphthalene-fused azo-ene-yne compounds are explored both computationally and experimentally. Calculations reveal that naphtho-fusion to an azo-ene-yne scaffold does not significantly alter the transition state energies compared to the benzene-based systems; however, fusing the naphthalene in an angular fashion leads to lower energy intermediates due to the creation of arenes possessing greater aromaticity. Experimentally, the cyclization of the angular systems yields not only the expected monomeric benzocinnolines and benzoisoindazoles, but also several dimeric structures, including one that readily isomerizes in the presence of light and/or trace acid.

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N‐Heteroacenes

Cited by 241 publications

References 58 publications

Understanding the Electronic Structure of Larger Azaacenes through DFT Calculations

Understanding the Electronic Structure of Larger Azaacenes through DFT Calculations

Effects of electronegative substitution on the optical and electronic properties of acenes and diazaacenes

Coarctate versus Pericyclic Reactivity in Naphthalene‐Fused Azo–Ene–Ynes: Synthesis of Benzocinnolines and Benzoisoindazoles

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