College of Chemistry , Beijing Normal University , Xinjiekouwaidajie 19 , Beijing 100875 , P. R. China.
Department of Chemistry , Renmin University of China , Beijing 100872 , P. R. China.
J Am Chem Soc. 2019 Mar 20;141(11):4597-4612. doi: 10.1021/jacs.8b09021. Epub 2019 Mar 11.
A new approach to anion sensing that involves excimer disaggregation induced emission (EDIE) is reported. It involves the anion-mediated disaggregation of the excimer formed from a cationic macrocycle. This leads to an increase in the observed fluorescence intensity. The macrocycle in question, cyclo[1] N, N-dimethyl- N, N-bis(6-(1 H-imidazolium-1-yl)pyridin-2-yl)pyridine-2,6-diamine[1]1,4-dimethylbenzene (1; prepared as its PF salt), is obtained in ca. 70% yield via a simple cyclization. X-ray diffraction analyses of single crystals revealed that, as prepared, this macrocycle exists in a supramolecular polymeric form in the solid state. Macrocycle 1 is weakly fluorescent in acetonitrile. The emission intensity is concentration dependent, with the maximum intensity being observed at [1] ≈ 0.020 mM. This finding is ascribed to formation of an excimer, followed possibly by higher order aggregates as the concentration of 1 is increased. Addition of tetrabutylammonium pyrophosphate (HPO) to 1 (0.020 mM in acetonitrile) produces a ca. 200-fold enhancement in the emission intensity (λ = 334 nm; λ = 390-650 nm). These findings are rationalized in terms of the HPO serving to break up essentially non-fluorescent excited-state dimers of 1 through formation of a highly fluorescent anion-bound monomeric complex, 1·HPO. A turn-on in the fluorescence intensity is also seen for HPO and, to a lesser extent, HCO. Little (HSO, NO) or essentially no (N, SCN, F, Cl, Br and I) response is seen for other anions. Solid-state structural analysis of single crystals obtained after treating 1 with HPO in the presence of water revealed a salt form wherein a HPO anion sits above the cone-like macrocycle.
一种涉及激基缔合物离解诱导发射（EDIE）的阴离子传感新方法被报道。它涉及由阳离子大环形成的激基缔合物的阴离子介导的离解。这导致观察到的荧光强度增加。所讨论的大环，环[1] N，N-二甲基-N，N-双（6-（1 H-咪唑-1-基）吡啶-2-基）吡啶-2,6-二胺[1]1,4-二甲基苯（1；以其 PF 盐形式制备），通过简单的环化以约 70%的产率获得。单晶的 X 射线衍射分析表明，该大环在固态中以超分子聚合物形式存在。大环 1 在乙腈中具有微弱的荧光。发射强度与浓度有关，在[1]≈0.020 mM 时观察到最大强度。这一发现归因于激基缔合物的形成，随后可能随着 1 的浓度增加而形成更高阶的聚集体。将四丁基焦磷酸氢盐（HPO）添加到 1（乙腈中 0.020 mM）中会使发射强度增强约 200 倍（λ=334nm；λ=390-650nm）。这些发现可以用 HPO 来解释，它通过形成高度荧光的阴离子结合单体复合物 1·HPO 来破坏 1 的基本上非荧光激发态二聚体。HPO 和 HCO 也会看到荧光强度的“开”。对于其他阴离子，几乎没有（HSO，NO）或基本上没有（N，SCN，F，Cl，Br 和 I）响应。在存在水的情况下用 HPO 处理 1 后获得的单晶的固态结构分析表明存在一种盐形式，其中 HPO 阴离子位于锥形大环上方。
