Four tetrahedral silicon‐centered derivatives of dibenzoylmethanatoboron difluoride (DBMBF₂) were synthesized and characterized. Their structural and optical features both in solution and the solid state were investigated by using X‐ray crystallography, steady‐state and time‐dependent spectroscopy, and DFT‐based calculations. In dilute solutions, the molar absorption coefficient increases from 40500 to 175200 M⁻¹ cm⁻¹ as the number of DBMBF₂ fragments in a molecule increases from one to four, while, in contrast, the nonradiative rate constant of fluorescence decay decreases from 0.49 to 0.34. In the solid state, absorption and emission spectra depend on the degree of crystallinity and microcrystal size. The tris‐DBMBF₂ derivative forms fully overlapping dimeric structures that exhibit excimer‐like fluorescence, which is accurately predicted by the quantum‐chemical calculations. The mono‐DBMBF₂ derivative exhibits fully reverse mechanofluorochromic behavior.

中文翻译：

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以四面体硅为中心的二苯甲酰基甲基氨基硼酸二氟化物：在溶液和固态下的合成，晶体结构和光物理行为。

合成并表征了四种以四面体硅为中心的二氟化二苯甲酰基甲基氨基硼酸衍生物（DBMBF ₂）。通过使用X射线晶体学，稳态和时间相关光谱以及基于DFT的计算，研究了它们在溶液和固态中的结构和光学特征。在稀溶液中，随着分子中DBMBF ₂片段的数量从一增加到四，摩尔吸收系数从40500增加到175200 M ^-1  cm ^-1，相反，荧光衰减的非辐射速率常数从0.49减少至0.34。在固态下，吸收和发射光谱取决于结晶度和微晶尺寸。tris‐DBMBF ₂衍生物形成完全重叠的二聚体结构，展现出准分子样荧光，这是通过量子化学计算准确预测的。mono-DBMBF ₂衍生物表现出完全相反的机械荧光色行为。