Herein we report simple pyridinium (1–3) and quinolinium (4) salts for the selective recognition of G-quadruplexes (G4s). Among them, the probe 1, interestingly, selectively discriminated parallel (c-KIT-1, c-KIT-2, c-MYC) G4s from anti-parallel/hybrid (22AG, HRAS-1, BOM-17, TBA) G4s at pH 7.2, through a switch on response in the far-red window. Significant changes in the absorption (broad 575 nm → sharp 505 nm) and emission of probe 1 at 620 nm, attributed to selective interaction with parallel G4s, resulted in complete disaggregation-induced monomer emission. Symmetrical push/pull molecular confinements across the styryl units in probe 1 enhanced the intramolecular charge transfer (ICT) by restricting the free rotation of CC units in the presence of sterically less hindered and highly accessible G4 surface/bottom tetrads in the parallel G4s, which is relatively lower extent in antiparallel/hybrid G4s. We confirm that the disaggregation of probe 1 was very effective in the presence of parallel G4–forming ODNs, due to the presence of highly available free surface area, resulting in additional π-stacking interactions. The selective sensing capabilities of probe 1 were analyzed using UV–Vis spectroscopy, fluorescence spectroscopy, molecular dynamics (MD)–based simulation studies, and ¹H NMR spectroscopy. This study should afford insights for the future design of selective compounds targeting parallel G4s.

本文我们报告简单吡啶鎓（1 - 3）和喹啉（4）的盐为G-四（G 4 S）的选择性识别。其中，有趣的是，探针1选择性地将平行 (c-KIT-1, c-KIT-2, c-MYC) G4s 与反平行/杂交 (22AG, HRAS-1, BOM-17, TBA) G4s 区分开来在 pH 7.2 时，通过远红色窗口中的开启响应。探针1在 620 nm 处的吸收（宽 575 nm → 锐角 505 nm）和发射的显着变化，归因于与平行 G4 的选择性相互作用，导致完全解聚诱导单体发射。探针1 中苯乙烯基单元上的对称推/拉分子限制在平行 G4 中存在空间位阻较小且高度可及的 G4 表面/底部四分体的情况下，通过限制 C C 单元的自由旋转来增强分子内电荷转移（ICT），这在反平行/杂化 G4 中的程度相对较低。我们确认探针1的解聚在平行 G4 形成 ODN 的存在下非常有效，因为存在高度可用的自由表面积，导致额外的 π 堆积相互作用。探针的选择性的感测能力1通过UV-Vis光谱，荧光光谱，分子动力学（MD）为基础的模拟研究进行了分析，和¹H 核磁共振光谱。这项研究应该为未来设计靶向平行 G4 的选择性化合物提供见解。