Peng Lu, Wei Ruirui, Guo Yifei, Zheng Xiaokun, Zheng Yue, Ding Yiwen, Xiang Yu, Tong Aijun
Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing, 100084, P. R. China.
RDFZ Chaoyang Branch School, 8 Sun Palace South Street, Beijing, 100028, P. R. China.
Chemistry. 2019 Jun 18;25(34):8043-8052. doi: 10.1002/chem.201900722. Epub 2019 May 10.
Tuning fluorescence colour of solid-state materials has become a topic of increasing interest for both fundamental mechanism study and practical applications such as sensors, optical recording and security printing. In this work, a fluorescent colour tuneable molecule BA-C16 is rationally designed and facilely synthesized by attaching flexible long alkyl chains to 2-hydroxybenzophenone azine (BA), which shows both aggregation-induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics. Compared to BA, the simple introduction of long alkyl chains in BA-C16 leads to an emission wavelength redshift from 542 to 558 nm. This strategy of extending emission wavelength is rarely reported, and is ascribed to the enlarged through-space π-conjugation between interplanar molecules in the aggregate of BA-C16. Three crystals of BA-C16 are obtained with green, yellowish green and yellow emission. According to characterization by X-ray crystallography, X-ray powder diffraction and differential scanning calorimetry, alkyl chains play an important role in inducing different stacking modes of the three crystals, which further leads to polymorph-dependent fluorescence colour. BA-C16 exhibits tuneable solid-state fluorescence upon vapor fumigation, or annealing based on a transition between a "near-monomer" crystalline state and a "dimer" crystalline state. BA-C16 is further applied for rewritable fluorescence printing tuned by vapor- and thermal-treatment.
调节固态材料的荧光颜色已成为一个越来越受关注的课题，无论是对于基础机理研究还是对于诸如传感器、光学记录和安全印刷等实际应用。在这项工作中，通过将柔性长烷基链连接到2-羟基二苯甲酮嗪（BA）上，合理设计并简便合成了一种荧光颜色可调分子BA-C16，该分子具有聚集诱导发光（AIE）和激发态分子内质子转移（ESIPT）特性。与BA相比，在BA-C16中简单引入长烷基链导致发射波长从542 nm红移至558 nm。这种延长发射波长的策略鲜有报道，这归因于BA-C16聚集体中平面间分子之间通过空间的π共轭增大。获得了三种具有绿色、黄绿色和黄色发射的BA-C16晶体。根据X射线晶体学、X射线粉末衍射和差示扫描量热法的表征，烷基链在诱导三种晶体的不同堆积模式中起重要作用，这进一步导致了多晶型依赖的荧光颜色。BA-C16在蒸汽熏蒸或基于“近单体”晶态和“二聚体”晶态之间的转变进行退火时表现出可调的固态荧光。BA-C16进一步应用于通过蒸汽和热处理调节的可重写荧光印刷。
