Quinoacridine Derivatives with One-Dimensional Aggregation-Induced Red Emission Property

A new series of acceptor–donor–acceptor (A–D–A) type quinoacridine derivatives (1–3) with aggregation-induced red emission properties were designed and synthesized. In these compounds, the electron-withdrawing 2-(3,5-bis­(trifluoromethyl)­phenyl)­acetonitrile groups act as electron-accepting units, while the alkyl-substituted conjugated core acts as electron-donating units. The restriction of intramolecular rotation was responsible for the AIE behavior of compounds 1–3. All compounds were employed as building blocks to fabricate one-dimensional (1-D) organic luminescent nano- or microwires based on reprecipitation or slow evaporation approaches. Morphological transition from zero-dimensional (0-D) hollow nanospheres to 1-D nanotubes has been observed by recording SEM and TEM images of aggregated sates of compound 2 in THF/H2O mixtures at different aging time. It was demonstrated that the synthesized compounds with different lengths of alkyl chains displayed different wire formation properties. The single-crystal X-ray analysis of compound 2 provided reasonable explanation for the formation of 1-D nano- or microstructures.

本研究设计并合成了一系列具有聚集诱导红光发射特性的新型受体-给体-受体（acceptor–donor–acceptor, A–D–A）型喹吖啶衍生物（1~3）。在该系列化合物中，吸电子的2-(3,5-双(三氟甲基)苯基)乙腈基团充当电子受体单元，而经烷基取代的共轭骨架则作为电子给体单元。分子内旋转受限是化合物1~3展现聚集诱导发光（aggregation-induced emission, AIE）行为的关键原因。所有化合物均作为构筑基元，通过再沉淀法或缓慢挥发法制备得到一维（1-D）有机发光纳米线或微米线。通过记录化合物2在不同陈化时间下的四氢呋喃（tetrahydrofuran, THF）/水混合溶剂聚集态的扫描电子显微镜（scanning electron microscope, SEM）与透射电子显微镜（transmission electron microscope, TEM）图像，可观测到其形貌从零维（0-D）空心纳米球向一维（1-D）纳米管的转变过程。研究表明，烷基链长度各异的目标化合物展现出不同的一维线结构制备性能。化合物2的单晶X射线衍射分析为一维纳米/微米结构的形成机制提供了合理解释。