Previously reported Lewis superacids are colorless and do not exhibit visual changes upon adduct formation. Herein, we combine the features of near Lewis superacidity with light absorption and emission in the visible range. Detailed (TD-)DFT considerations lead to the design of bis(alizarinato)silane 1 as a powerful chromogenic Lewis acid, that responds to one or two fluoride ions with different optical outputs. Lewis adducts of 1 are synthesized, and the coordination-state-dependent absorption and emission maxima verified experimentally. Reaction with, for example, sodium fluoride, reveals the simultaneous participation of the Lewis acidic silicon center and the Lewis basic alizarin carbonyl functions, promising its additional use as a salt-selective molecular receptor. Although the poor solubility and moisture intolerance of 1 for the moment hinder real practical applications, this study paves the way for dual-gated fluoride ion sensing.

中文翻译：

---

双（alizarinato）硅烷：硅设计和强大的发色路易斯酸作为双门控氟化物离子探针的合成。

先前报道的路易斯超酸是无色的，并且在加合物形成时不显示视觉变化。在这里，我们结合了近路易斯超酸度的特征与可见光范围内的光吸收和发射。详细的（TD-）DFT考虑因素导致了双（硅氮杂萘基）硅烷1的设计成为一种强大的发色路易斯酸，该路易斯酸可响应一个或两个具有不同光学输出的氟离子。1的路易斯加合物合成，并通过实验验证了与配位态有关的吸收和发射最大值。与氟化钠的反应表明，路易斯酸性硅中心和路易斯碱性茜素羰基官能团同时参与，从而有望进一步用作盐选择性分子受体。尽管目前不良的溶解度和不耐湿性（1）阻碍了实际的实际应用，但这项研究为双门控氟化物离子感测铺平了道路。