A freely soluble dianthracenoindacene derivative has been synthesized using an ‘inside-out’ Friedel–Crafts alkylation method and is the first fluorescent diacenoindacene reported. Linear fusion of the anthracenes is confirmed by X-ray diffraction studies on the neutral molecule as well as its dianion. Based on predictions from our previous studies, this is also the least antiaromatic diacenoindacene derivative yet to be prepared, which is reflected in its highly negative and irreversible reduction. With its paratropicity essentially eliminated, we posit that the molecule is no longer deactivated by a conical intersection, typical of antiaromatic molecules, and therefore fluorescence is restored. This follows the trend shown in the related dianthracenopentalenes, with the reappearance of fluorescence when the outer acene groups are extended to linearly-fused anthracene moieties.

中文翻译：

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荧光二蒽基并苯的合成与表征

使用“由内而外”Friedel-Crafts 烷基化方法合成了一种可自由溶解的二苯并吲哚衍生物，并且是第一个报道的荧光二苯并茚。通过对中性分子及其二价阴离子的 X 射线衍射研究证实了蒽的线性融合。根据我们之前研究的预测，这也是尚未制备的抗芳香二苯并茚衍生物最少，这反映在其高度负和不可逆的还原上。由于其副向性基本上被消除，我们假设该分子不再因锥形交叉而失活，这是反芳香族分子的典型特征，因此荧光得以恢复。这遵循相关二蒽五烯中显示的趋势，