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Author: Dmitrieva, Evgenia × Publisher: Weinheim : Wiley-VCH ×

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    Persistent peri-Heptacene: Synthesis and In Situ Characterization
    (Weinheim : Wiley-VCH, 2021) Ajayakumar, M.R.; Ma, Ji; Lucotti, Andrea; Schellhammer, Karl Sebastian; Serra, Gianluca; Dmitrieva, Evgenia; Rosenkranz, Marco; Komber, Hartmut; Liu, Junzhi; Ortmann, Frank; Tommasini, Matteo; Feng, Xinliang
    n-peri-Acenes (n-PAs) have gained interest as model systems of zigzag-edged graphene nanoribbons for potential applications in nanoelectronics and spintronics. However, the synthesis of n-PAs larger than peri-tetracene remains challenging because of their intrinsic open-shell character and high reactivity. Presented here is the synthesis of a hitherto unknown n-PA, that is, peri-heptacene (7-PA), in which the reactive zigzag edges are kinetically protected with eight 4-tBu-C6H4 groups. The formation of 7-PA is validated by high-resolution mass spectrometry and in situ FT-Raman spectroscopy. 7-PA displays a narrow optical energy gap of 1.01 eV and exhibits persistent stability (t1/2≈25 min) under inert conditions. Moreover, electron-spin resonance measurements and theoretical studies reveal that 7-PA exhibits an open-shell feature and a significant tetraradical character. This strategy could be considered a modular approach for the construction of next-generation (3 N+1)-PAs (where N≥3). © 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH
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    On the Electrochemical Reduction of 4-(Thiazol-2-ylazo)-Substituted 1-Chloronaphthalenes: Formation and Characterization of Stable Radical Anions
    (Weinheim : Wiley-VCH, 2020) Dmitrieva, Evgenia; Popov, Alexey A.; Yu, Xiuling; Hartmann, Horst
    The electrochemical reduction of two chloro-substituted 4-(thiazol-2-ylazo)has been studied by means of spectroelectrochemistry and simulated with the DFT method. Whereas the 1-chloro-4-(4-chlorothiazol-2-ylazo)forms both a stable radical anion and a dianion, the dianion of 1-chloro-4-(thiazol-2-ylazo)is instable. In the radical anion of both compounds, the spin densities are high not only at the azo moiety but also at C3 in the naphthalene and at C5 in the thiazole moiety. This is in agreement with former experimental results demonstrating the remarkable reactivity of these positions towards thiols which can act as nucleophiles as well as electron donors. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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    On the Preparation and Spectroelectrochemical Characterization of Certain 2,5-Bis(het)aryl Substituted Thiophenes
    (Weinheim : Wiley-VCH, 2024) Dmitrieva, Evgenia; Barche, Jens; Popov, Alexey A.; Hartmann, Horst
    In this work, a series of novel 2,5-bis(het)aryl and 2,5-bis-thienyl substituted thiophenes have been synthesized and characterized by ultraviolet-visible-near infrared (UV-Vis-NIR) absorption and fluorescence spectroscopy as well as cyclic voltammetry. From the electron paramagnetic resonance (EPR)/UV-Vis-NIR spectroelectrochemical data, information about the optical and magnetic properties of the charged species of these compounds have been provided. The spin distributions in the electrochemically generated radical ions were estimated experimentally and compared with theoretical data.
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    The First Products of Aniline Oxidation – SERS Spectroelectrochemistry
    (Weinheim : Wiley-VCH, 2019) Morávková, Zuzana; Dmitrieva, Evgenia
    There are different opinions on the first products of aniline oxidation throughout the scientific community. While electrochemists basically accept only linear oligomers with repeating units joint in para positions, chemists have proposed formation of various branched and polycyclic oligomers. It was also suggested that one of these structures, N-phenyl-phenazinium cation, is responsible for the adherence of polyaniline films to substrates. In this work, a surface enhanced Raman spectroscopic and spectroelectrochemical analysis of the species adsorbed onto gold surface in aniline-containing solution at pH 1 and 5 is presented. The influence of the pH value on the oligomer structure is declared. The results are discussed in the context of linear and branched/phenazine-like aniline oligomers. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim