Non-conjugated fluorescent molecular cages of salicylaldehyde-based tri-Schiff bases: AIE, enantiomers, mechanochromism, anion hosts/probes, and cell imaging properties

Xiaohong Zhang,‡^a Jun Shi,‡^b Guangyu Shen,^a Fei Gou,^a Jinghui Cheng,^a Xiangge Zhou,^a and Haifeng Xiang∗^a

Mater. Chem. Front. 2017, 2017, 1, 1041--1050

对非共轭双希夫碱Salen荧光材料的一个拓展，其最大优点是可以用做阴离子受体和探针。

Luminescent organicmaterials are commonly polycyclic aromatic molecules with planar extended π-electron conjugation. In present work, however, we report a series of novel and simple salicylaldehyde-based tri-Schiff bases (TSBs, 15 samples), which have a non-conjugated trimethylamine bridge but emit strong blue, green, and yellow aggregation-induced emission (AIE) with large Stokes shifts (up to 167 nm) and high fluorescence quantum yields (up to 0.18). Mechanochromic fluorescence enhancement and enantiomers are also found in TSBs solids. Moreover, these flexible and tripod-like molecular cages acting as ideal and universal anion hosts can be used to detect anions with turn–on fluorescence signals (fluorescence quantum yields up to 0.51). Combining with their advantages of AIE and biocompatibility, TSBs have potential application in living cell imaging. The inherent relationships between their chemical structures and AIE/anion host properties are studied, which provide unequivocal insights for the design of non-conjugated fluorescent materials.