Department of Chemistry, Birla Institute of Technology and Science, Pilani, Telangana 500078, India.
Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice, CZ 53210, Czech Republic.
J Org Chem. 2021 Nov 5;86(21):14663-14671. doi: 10.1021/acs.joc.1c01488. Epub 2021 Oct 14.
A Y-shaped push-pull dye () with ,-dimethylanilino donors and a benzonitrile acceptor connected via an imidazole-based π-conjugated spacer was designed. It showed a dark yellow color in solution due to facile intramolecular charge-transfer interaction, but no fluorescence was detected, presumably due to the photo-induced electron transfer effect of the imidazole moiety. However, addition of nerve agents such as diethyl chlorophosphate (DCP, sarin mimic) and diethyl cyanophosphate (DCNP, Tabun mimic) resulted in a blue-colored fluorescence with fading of the native dark yellow color. Mechanistic studies indicated nucleophilic attack of imidazole at the phosphorus of DCP or DCNP, leading to the formation of a phosphorylated intermediate, which undergoes time-dependent hydrolysis (∼24 h) in aqueous medium. This process recovers the free probe (enzyme-like behavior) and releases a less-toxic organophosphate compound as the byproduct. The phosphorylated derivative of , formed during such interaction, shows a different electronic behavior, which reduces the extent of charge-transfer interaction as well as nonradiative decay and supports emissive properties. Considering the high sensitivity of towards DCP and DCNP with LOD 35 and 42 ppb, we prepared easy test strips for on-site vapor-phase detection of nerve agents.
一种 Y 型推拉染料（），其供体为，-二甲基苯胺和苯甲腈受体通过基于咪唑的π共轭间隔基连接。由于易于发生分子内电荷转移相互作用，它在溶液中呈现深黄色，但未检测到荧光，这可能是由于咪唑部分的光致电子转移效应。然而，加入神经毒剂，如二乙基氯膦（DCP，沙林模拟物）和二乙基氰膦（DCNP，塔崩模拟物），会导致蓝色荧光的出现，同时原生深黄色会褪色。机理研究表明，咪唑在 DCP 或 DCNP 的磷原子上发生亲核攻击，导致形成磷酸化中间产物，该中间产物在水介质中经历时控水解（约 24 小时）。该过程会恢复游离探针（酶样行为），并释放出毒性较低的有机磷化合物作为副产物。在这种相互作用过程中形成的，形成了一种不同的电子行为，这减少了电荷转移相互作用以及非辐射衰减的程度，并支持发射特性。考虑到对 DCP 和 DCNP 的高灵敏度，检出限分别为 35 和 42 ppb，我们制备了易于制备的试纸条，用于现场气相检测神经毒剂。
