nonalternant

  • 文章类型: Journal Article
    分裂azulene的五元和七元环并将它们分别嵌入共轭主链中,提供了类azulene多环芳烃(PAHs),对量子化学和材料化学非常感兴趣。然而,合成的可及性构成了重大挑战。在这项研究中,我们介绍了一种新型的类甘菊环类PAH的合成,Pery-57,可以将其视为将perylene骨架整合到分裂的azulene中。Pery-57的紧凑结构表现出几个有趣的特点,包括1200nm的NIRII吸收,3.5D的大量偶极矩,头对尾交替柱状填料。此外,Pery-57具有显着的氧化还原特性。阳离子自由基Pery-57•+容易捕获氢原子。可变温度NMR(VT-NMR)和可变温度EPR(VT-EPR)研究表明,阴离子Pery-572-具有开壳单线态基态,并显示出明显的全球反芳香性。指示Pery-572+也被预测表现出双自由基特性。尽管带有三个庞大的取代基,Pery-57显示出p型传输特性,迁移率为0.03cm2V-1s-1,这归因于其独特的类azulene结构。总的来说,这项工作引起了人们对类似于azulene的PAHs的兴趣,非交替PAHs的独特成员,展示了卓越的性能和应用。
    Splitting the five and seven-membered rings of azulene and embedding them separately into a conjugated backbone provides azulene-like polycyclic aromatic hydrocarbons (PAHs), which are of great interest in quantum and material chemistry. However, the synthetic accessibility poses a significant challenge. In this study, we present the synthesis of a novel azulene-like PAH, Pery-57, which can be viewed as the integration of a perylene framework into the split azulene. The compact structure of Pery-57 displays several intriguing characteristics, including NIR II absorption at 1200 nm, a substantial dipole moment of 3.5 D, and head-to-tail alternating columnar packing. Furthermore, Pery-57 exhibits remarkable redox properties. The cationic radical Pery-57•+ readily captures a hydrogen atom. Variable-temperature NMR (VT-NMR) and variable-temperature EPR (VT-EPR) studies reveal that the dianion Pery-572- possesses an open-shell singlet ground state and demonstrates significant global anti-aromaticity. The dication Pery-572+ is also predicted to exhibit diradical character. Despite bearing three bulky substituents, Pery-57 displays p-type transport characteristics with a mobility of 0.03 cm2 V-1 s-1, attributed to its unique azulene-like structure. Overall, this work directs interest in azulene-like PAHs, a unique member of nonalternant PAHs showcasing exceptional properties and applications.
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  • 文章类型: Journal Article
    Nonalternant aromatic π-electron systems show promises for surface functionalization due to their unusual electronic structure. Based on our previous experiences for metal surfaces, we investigate the adsorption structures, adsorption dynamics and bonding characteristics of azulene and its alternant aromatic isomer naphthalene on the Si(001) surface. Using a combination of density functional theory,ab initiomolecular dynamics, reaction path sampling and bonding analysis with the energy decomposition analysis for extended systems, we show that azulene shows direct adsorption paths into several, strongly bonded chemisorbed final structures with up to four covalent carbon-silicon bonds which can be described in a donor-acceptor and a shared-electron bonding picture nearly equivalently. Naphthalene also shows these tetra-σ-type bonding structures in accordance with an earlier study. But the adsorption path is pseudo-direct here with a precursor intermediate bonded via one aromatic ring and strong indications for a narrow adsorption funnel. The four surface-adsorbate bonds formed lead for both adsorbates to a strong corrugation and a loss of aromaticity.
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