Effects of cyano groups on the properties of thiazole-based beta-ketoiminate boron complexes: aggregation-induced emission and mechanofluorochromism
Effects of cyano groups on the properties of thiazole-based beta-ketoiminate boron complexes: aggregation-induced emission and mechanofluorochromism
复制标题
氰基对噻唑基β-酮亚胺硼配合物性能的影响：聚集诱导发射和机械荧光变色
DOI：
10.1039/c6ra14595g
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发表时间：
2016
期刊：
影响因子：
3.9
通讯作者：
Zhao Feng
中科院分区：
文献类型：
--
作者：
Zhou Lin;Xu Defang;Gao Huaizhi;Han Aixia;Yang Yan;Zhang Chao;Liu Xingliang;Zhao Feng
设计并成功合成了一系列新的噻唑基β-酮亚胺硼配合物BF2-TT-CN、BPh_2-TT-CN、BF_2-TT和BPh_2-TT。这些化合物表现出明显的分子内电荷转移(ICT)，从电子供体(三苯胺单元)到电子受体(β-亚氨基烯醇硼部分)。特别值得注意的是，这些化合物表现出强烈的氰基依赖的聚集诱导发射(AIE)和机械荧光(MFC)性质。在氰基取代的衍生物BF2-TT-CN和BPh2-TT-CN中，氰基的高电子亲和力赋予了相对于BF2-TT和BPh2-TT更强的ICT性能。此外，氰基的内部空间位阻导致了更多的扭曲构象，使BF2-TT-CN和BPh2-TT-CN具有明显的AIE特征和可逆的机械荧光变色。通过重复研磨-发烟过程，BF2-TT-CN(从亮黄色发射到橙色，λem从542到599 nm)和BPh2-TT-CN(从亮黄色到橙色发射，λem从549到566 nm)的MFC行为是可逆的。然而，缺少氰基的BF2-TT和BPh2-TT没有表现出AIE和机械荧光变色，部分原因是它们的扭曲构型相对较弱。因此，氰基的引入对BF2-TT-CN和BPh2-TT-CN具有较强的ICT行为和优异的机械荧光AIE性能起着重要的作用。这些结果将对理解AIE和MFC机理以及设计新的MFC AIE材料有很大的帮助。
A series of new thiazole-based β-ketoiminate boron complexes BF2-TT-CN, BPh2-TT-CN, BF2-TT and BPh2-TT, have been designed and successfully synthesized. These compounds show clear intramolecular charge transfer (ICT) from the electron donor (triphenylamine unit) to the electron acceptor (the β-iminoenolate boron moiety). It is particularly noteworthy that these compounds exhibit strong cyano-dependent aggregation-induced emission (AIE) and mechanofluorochromic (MFC) properties. In the cyano-substituted derivatives, BF2-TT-CN and BPh2-TT-CN, the high electron affinity of the cyano group confers stronger ICT properties relative to BF2-TT and BPh2-TT. In addition, the internal steric hindrance arising from the cyano group results in more twisted conformations, endowing BF2-TT-CN and BPh2-TT-CN with evident AIE characteristics and reversible mechanofluorochromism. The MFC behavior of BF2-TT-CN (from bright yellow to orange emission, λem from 542 to 599 nm) and BPh2-TT-CN (from bright yellow to orange emission, λem from 549 to 566 nm) is reversible by repeating the grinding-fuming process. However, BF2-TT and BPh2-TT, which lack cyano groups, exhibit no AIE and mechanofluorochromism, partly because of their relatively weak twisted configurations. Therefore, the introduction of the cyano group plays an important role in the strong ICT behavior and excellent mechanofluorochromic AIE properties of BF2-TT-CN and BPh2-TT-CN. These results will be of great help in understanding the AIE and MFC mechanisms and designing new MFC AIE materials.