Dibenzoborole derivatives containing four-coordinated boron were designed to realize emission from the bond-cleavage-induced intramolecular charge transfer (BICT) transition. A series of electron-donating and accepting groups were introduced into dibenzoborole through regioselective bromination and Suzuki–Miyaura coupling reaction in high yields. The synthesized dibenzoboroles showed dual-emissive properties composed of emission from the π–π* transition with four-coordinated boron and the BICT transition with a three-coordinated state. The influence of the substituents on the optical properties was experimentally and theoretically analyzed. Next, on the basis of the dual-emissive properties, it was demonstrated that dibenzoborole was feasible as a ratiometric fluorescent sensor for discriminating the viscosity of solvent alkanes including the length of alkane chains with a wide detection range. Finally, it was demonstrated that this detection system with a ratiometric output was applicable for evaluating viscosity with mixture samples and various kinds of natural oils.

中文翻译：

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二苯并硼键的键断裂诱导的分子内电荷转移发射的设计及其在区分烷烃链长的比例传感器中的应用

设计了含有四配位硼的二苯并硼衍生物，以实现键断裂诱导的分子内电荷转移（BICT）跃迁的发射。通过区域选择性溴化和Suzuki-Miyaura偶联反应，高产率地将一系列给电子和受电子基团引入二苯并硼烷中。合成的二苯并硼化合物显示出由四配位的π-π*跃迁和三配位的BICT跃迁组成的双发射性质。实验和理论分析了取代基对光学性能的影响。接下来，基于双重发射特性，结果表明，二苯并硼烷作为比率荧光传感器可用于区分溶剂烷烃的粘度，包括检测范围很广的烷烃链的长度。最后，证明了该具有比例输出的检测系统适用于评估混合物样品和各种天然油的粘度。