Excellent Crystallinity and Stability Covalent-Organic Frameworks with High Emission and Anions Sensing
Excellent Crystallinity and Stability Covalent-Organic Frameworks with High Emission and Anions Sensing
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优异的结晶度和稳定性共价有机框架，具有高发射和阴离子传感功能
DOI：
10.1002/marc.202200393
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发表时间：
2022-06-24
影响因子：
4.6
通讯作者：
Lee，Kyu Hyoung
中科院分区：
文献类型：
--
作者：
Wan，Jieqiong;Shi，Wei;Lee，Kyu Hyoung
共价有机骨架（COFs）是一类具有高π共轭和周期性骨架的新型多孔晶体骨架。一些COF中的高度有序的π共轭结构允许激子在框架上迁移和能量转移，这导致良好的荧光探测能力。在这项工作中，通过希夫碱缩合反应成功地缩合了两种COF（TFHPB-TAPB-COF和TFHPB-TTA-COF）。亚胺键和羟基之间的分子内氢键形成激发态分子内质子转移（ESIPT）策略。由于骨架中存在分子内氢键，这两种COFs具有较高的结晶度、显著的稳定性和优异的发光性能。COF通过荧光关闭对氟阴离子表现出良好的灵敏度和选择性。其他卤素阴离子（氯离子、溴离子和碘离子）和酸阴离子（硝酸根和碳酸氢根）保持不活跃。这些结果表明，只有氟阴离子能够打开氢键相互作用，从而打破ESIPT策略。该传感器对氟离子的检测限可达纳摩尔级，是目前性能最好的氟离子传感器。
Covalent–organic frameworks (COFs) are a new class of porous crystalline frameworks with highπ‐conjugation and periodical skeletons. The highly orderedπ‐conjugation structures in some COFs allow exciton migration and energy transfer over the frameworks, which leads to good fluorescence probing ability. In this work, two COFs (TFHPB‐TAPB‐COF and TFHPB‐TTA‐COF) are successfully condensed via the Schiff base condensation reaction. The intramolecular hydrogen bonds between imine bonds and hydroxyl groups form the excited‐state intramolecular proton transfer (ESIPT) strategy. Owing to intramolecular hydrogen bonds in the skeleton, the two COFs show high crystallinity, remarkable stability, and excellent luminescence. The COFs represent a good sensitivity and selectivity to fluoride anions via fluorescence turn‐off. Other halogen anions (chloride, bromide, and iodine) and acid anions (nitrate and hydrogen carbonate) remain inactive. These results imply that only fluoride anion is capable of opening the hydrogen bond interaction and hence break the ESIPT strategy. The detection limit toward fluoride anion is down to nanomoles level, ranking the best performances among fluoride anion sensors systems.