Beijing Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875, People's Republic of China.
Dalton Trans. 2018 Oct 2;47(38):13730-13738. doi: 10.1039/c8dt03179g.
A D-π-A Schiff-base compound, 2-amino-3({[4-(diethylamino)-2-hydroxylphenyl]methylene}amino)-but-2-enedinitrile (H2L), was prepared using diaminomaleonitrile and 4-(N,N-diethylamino)salicylaldehyde. Compared with H2L at 293 K, a low temperature of 100 K makes the parallel aromatics in H2L come closer and fluorescence emission becomes weaker because of π-π interaction-caused quenching. After grinding the crystals of H2L, the colour changed from dark brown-red to yellow under room light and the fluorescence emission enhanced about 9-fold due to the damage of the intermolecular hydrogen bonds, leading to a decrease of non-radiative transition. H2L showed aggregation-induced emission enhancement (AIEE) characteristics in THF/H2O, whose mechanism is attributed to the restriction of intramolecular rotation (RIR). The UV-Vis spectra of H2L with Cu2+ in THF/H2O showed that at first a CuL complex was formed and subsequently a CuL' complex (H2L' = N',N'-bis(4-N',N'-diethylsalicylidene) ethylenediamine) was obtained. The CuL complex turned into the CuL' complex as time prolonged. H2L acted as a dual channel chemosensor for Cu2+ ions in THF/HEPES (v/v: 2 : 8, pH = 8.0) and the CuL complex was stable in this medium. H2L is also a naked-eye probe for Mn2+ ions in CH3CN. The limits of detection are much lower than the allowable level of copper(ii) and manganese(ii) in drinking water set by the World Health Organization (WHO).
一种 D-π-A 席夫碱化合物，2-氨基-3({[4-(二乙氨基)-2-羟基苯基]亚甲基}氨基)-丁-2-烯二腈（H2L），是由二氨基马来腈和 4-（N，N-二乙氨基）水杨醛制备的。与 293 K 下的 H2L 相比，低温 100 K 使得 H2L 中的平行芳环更加接近，由于π-π 相互作用引起的猝灭，荧光发射变得更弱。研磨 H2L 的晶体后，在室温下颜色从深棕红色变为黄色，荧光发射增强了约 9 倍，这是由于分子间氢键的破坏，导致非辐射跃迁减少。H2L 在 THF/H2O 中表现出聚集诱导发光增强（AIEE）特性，其机制归因于分子内旋转的限制（RIR）。在 THF/H2O 中，H2L 与 Cu2+ 的紫外-可见光谱表明，首先形成了一个 CuL 配合物，随后形成了一个 CuL'配合物（H2L'=N'，N'-双（4-N'，N'-二乙基亚水杨基）乙二胺）。随着时间的延长，CuL 配合物转化为 CuL'配合物。H2L 作为一种在 THF/HEPES（v/v：2:8，pH=8.0）中对 Cu2+离子的双通道化学传感器，CuL 配合物在该介质中稳定。H2L 也是 CH3CN 中 Mn2+离子的肉眼探针。检测限远低于世界卫生组织（WHO）规定的饮用水中铜（ii）和锰（ii）的允许水平。
