三苯基咪唑衍生物的聚集诱导发光性质及其细胞成像应用

Aggregation-Induced Emission and Cell Imaging of Triphenylimidazole Derivatives

聚集诱导发光(AIE)材料在生物医学领域有很大优势,尤其为生物成像研究开启了新局面.通过2,4,5-三苯基咪唑衍生物与1,4-二溴丁烷/1-溴丁烷亲核取代反应,合成了2个丁烷桥联的双咪唑衍生物及2个1-位丁基取代的单咪唑衍生物.4个产物都表现出优异的AIE性质,其中含有甲氧基助色团的衍生物具有更长的发射波长.机理研究表明限制扭曲的分子内电荷转移是这类结构具有AIE活性的原因,因此,2-位强吸电子芳基是它们具有AIE活性的决定因素.此外,咪唑环1-位取代基的空间效应对AIE也非常重要,因为较大体积的1-位取代基使分子呈扭曲构象,从而限制聚集态π-π堆积作用.最后,研究了1-位丁基取代的单咪唑衍生物的细胞染色和成像性能,结果显示二者在蓝色、绿色及红色通道都表现出不错的荧光成像能力,但在不同颜色通道观察到的细胞被染色区域不完全相同.

Aggregation-induced emission(AIE)-active materials have great advantages in the biomedical field and open up a whole new world of opportunity for bioimaging.Herein,two butylidene-bridged bisimidazole derivatives and two butyl-substituted monoimidazole derivatives were easily synthesized from dibromobutane/bromobutane and 2,4,5-triphenyl-1H-imidazole derivatives.All the obtained imidazole derivatives showed excellent AIE properties,and the derivatives containing methoxy groups exhibited red-shifted emission.The research on AIE mechanism indicated that the restriction of twisted intramolecular charge transfer(TICT)mechanism was responsible for the AIE behaviors of these imidazole derivatives.Therefore,the strong electron-withdrawing nitro group is crucial for their AIE property.In addition,the steric effect of the substituent group at 1-position of imidazole ring is also indispensable for AIE,because it results in the twisted conformation and thus hampers the intermolecularπ-πstacking interactions.Ultimately,the cell staining and bioimaging behaviour of butyl-substituted monoimidazole derivatives were investigated.Both of them displayed an excellent bioimaging performance in blue,green and red channels,but the different staining regions in cells were observed in different channels.