近日，华南理工大学苗新蕊团队研究了多刺激荧光传感的炔基共价有机框架的结构调控。2025年4月24日，《结构化学》杂志发表了这一成果。

具有精确结构和永久孔隙率的刺激响应二维（2D）共价有机框架（COF）已被用作传感器平台。框架内骨架的轻微变化会导致外部刺激（如溶剂、pH值和水）产生不同的电子状态。在此，研究组引入了一种具有高平面度的炔基结构单元（ETBA），以高产率、良好的结晶度和化学稳定性合成了两种亚胺基炔基COF（ETBA-TAPE-COF和ETBA-PYTA-COF）。由于乙炔键的存在，ETBA-TAPE-COF不采用完全重叠的AA堆叠模式。相对于乙炔键，沿平行方向发生轻微的层间位移，这有助于降低构型能量。

此外，芘基团的引入有助于ETBA-PYTA-COF的高π电子迁移率。在质子化和分子内电荷转移（ICT）过程中，吸电子基团（ETBA）和供电子基团（PYTA）之间的相互作用分别赋予ETBA-PYTA-COF优异的酸致变色和溶剂致变色性能。在此基础上，成功建立了一种荧光传感器，可用于快速响应有机溶剂中痕量的水。相比之下，ETBA-TAPE-COF由于其比ETBA-PYTA-COF更高的HOMO-LUMO能隙而没有表现出这些光物理性质。这项工作提出了一种在不引入额外官能团的情况下设计和制备具有独特光物理性质的COF的新策略。

附：英文原文

Title: Structural regulation of alkynyl-based covalent organic frameworks for multi-stimulus fluorescence sensing

Author: anonymous

Issue&Volume: 2025-04-24

Abstract: Stimuli-responsive two-dimensional (2D) covalent organic frameworks (COFs) with precise structures and permanent porosity have been employed as platforms for sensors. The slight change of the backbones inside the framework leads to different electronic states by external stimuli, such as solvent, pH, and water. Herein, we introduced an alkynyl-based building block (ETBA) with high planarity to synthesize two imine-based alkynyl-COFs (ETBA-TAPE-COF and ETBA-PYTA-COF) with high yield, good crystallinity, and chemical stability. Due to the presence of acetylene bonds, ETBA-TAPE-COF does not adopt the completely overlapping AA stacking mode. Slight interlayer displacement occurs along the parallel direction relative to the acetylene linkages, which facilitates lower configurational energy. Additionally, the introduction of pyrene group contributes to high π-electron mobility of ETBA-PYTA-COF. The interactions between electron-withdrawing group (ETBA) and electron-donating group (PYTA) during processes of protonation and intramolecular charge transfer (ICT) endow ETBA-PYTA-COF with excellent acidochromic and solvatochromic properties, respectively. Based on this, a fluorescence sensor is successfully established, which can be used for rapid response to trace amounts of water in organic solvents. In contrast, ETBA-TAPE-COF does not exhibit these photophysical properties due to its higher HOMO–LUMO gap compared to ETBA-PYTA-COF. This work proposes a new strategy for designing and preparing COFs with unique photophysical properties without introducing additional functional groups.

DOI: 10.1016/j.cjsc.2025.100604

Source: http://cjsc.ac.cn/cms/issues/798