Bliksted Roug Pedersen Viktor, Zalibera Michal, Lirette Frédéric, Ouellette Jérémie, Lanza Arianna, Fernández Israel, Rapta Peter, Morin Jean-François, Brøndsted Nielsen Mogens
Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen Ø, Denmark.
Institute of Physical Chemistry and Chemical Physics, Slovak University of Technology in Bratislava, Radlinského 9, SK-81237, Bratislava, Slovak Republic.
Angew Chem Int Ed Engl. 2025 Mar 17;64(12):e202422275. doi: 10.1002/anie.202422275. Epub 2025 Jan 9.
The introduction of 4,5-dihydroazuleno[2,1,8-ija]azulene as a central core between two 1,4-dithiafulvene (DTF) units provides a novel class of extended tetrathiafulvalene (TTF) electron donors. Herein we present the synthesis of such compounds with the azulenoazulene further expanded by annulation to benzene, naphthalene, or thiophene rings. Moreover, unsymmetrical donor-acceptor chromophores with one DTF and one carbonyl at the central core are presented. The effect of the odd-membered rings of the polycyclic aromatic hydrocarbon cores on the geometrical features and the extent of bond conjugation in these systems were investigated by UV/Vis absorption spectroscopy, (spectro)electrochemical studies, X-ray and electron diffraction, and computational studies. Altogether these studies reveal that, upon oxidation, the non-planar core of the bis(benzo)-fused dihydro-azulenoazulene-extended TTF generates a large 22π-aromatic system (together with two 6π-aromatic 1,3-dithiolium appendages) characterized by significant bond length equalizations. The dication formed by oxidation is EPR silent, indicating a singlet ground state. Computations reveal that the closed-shell singlet species and its open-shell singlet counterpart are nearly degenerate and of lower energy than a triplet species. According to cyclic voltammetry, the compounds can be oxidized further and present multi-redox systems.
将4,5-二氢薁并[2,1,8-ija]薁作为两个1,4-二硫富瓦烯（DTF）单元之间的中心核引入，提供了一类新型的扩展四硫富瓦烯（TTF）电子供体。在此，我们报道了此类化合物的合成，其中薁并薁通过与苯、萘或噻吩环环合进一步扩展。此外，还展示了在中心核带有一个DTF和一个羰基的不对称供体-受体发色团。通过紫外/可见吸收光谱、（光谱）电化学研究、X射线和电子衍射以及计算研究，研究了多环芳烃核的奇数元环对这些体系几何特征和键共轭程度的影响。这些研究总共表明，氧化时，双（苯并）稠合二氢薁并薁扩展TTF的非平面核产生一个大的22π芳香体系（连同两个6π芳香1,3-二硫鎓附属物），其特征是键长显著均等化。氧化形成的双阳离子是EPR沉默的，表明其基态为单线态。计算表明，闭壳单线态物种及其开壳单线态对应物几乎简并，且能量低于三线态物种。根据循环伏安法，这些化合物可以进一步氧化，并呈现多氧化还原体系。
