Ministry of Education Key Laboratory of Analytical Science for Food Safety and Biology, Fujian Provincial Key Laboratory of Analysis and Detection Technology for Food Safety, College of Chemistry, Fuzhou University, Fuzhou, Fujian 350108, China.
ACS Appl Mater Interfaces. 2022 May 11;14(18):21750-21757. doi: 10.1021/acsami.2c04391. Epub 2022 Apr 28.
Nanomaterials with enzyme-like characteristics (called nanozymes) show their extreme potentials as alternatives to natural enzymes. Covalent organic frameworks (COFs) as metal-free nanozymes have attracted huge attention for catalytic applications due to their flexible molecular design and synthetic strategies and conjugated, porous, and chemically stable architectures. Designing high-performance two-dimensional (2D) porous COF materials embedded with functional building units for modulating nanozymes' catalytic activity is of immense importance in contemporary research. The proper combination of donor-acceptor (D-A) fragments within a porous COF skeleton is an effective strategy to decrease the band gap and provide a strong charge-transfer pathway for highly effective charge separation. Herein, two donor-acceptor heteroporous COFs using an electron-deficient 4,4'-(thiazolo[5,4-]thiazole-2,5-diyl)dibenzaldehyde (Tz) unit or 4,4'-(benzo[][1,2,5]thiadiazole-4,7-diyl)dibenzaldehyde (Td) unit and electron-rich tetrakis(4-aminophenyl)ethane (ETTA) linkers were presented. The resulting crystalline and heteroporous COFs showed outstanding oxidase-like activity under light irradiation, which can catalyze the oxidation of typical substrates and corresponding evolution in color and absorption. The light-activatable ETTA-Tz COF with prominent oxidase-like activity can serve as a colorimetric probe for quantitative detection of sulfide ions with a linear range of 1-50 μM and a detection limit of 0.27 μM within 3 min. The colorimetric approach could also be used for sulfide ion detection in human serum samples. The research demonstrated the future potential of D-A motifs within fully conjugated COFs to obtain excellent mimic enzyme activity.
具有酶样特性的纳米材料（称为纳米酶）作为天然酶的替代品显示出了巨大的潜力。由于其灵活的分子设计和合成策略以及共轭、多孔和化学稳定的结构，无金属的共价有机框架（COFs）作为纳米酶在催化应用中引起了极大的关注。设计具有嵌入式功能构筑单元的高性能二维（2D）多孔 COF 材料以调节纳米酶的催化活性，在当代研究中具有重要意义。在多孔 COF 骨架内适当组合给体-受体（D-A）片段是降低带隙和提供强电荷转移途径以实现高效电荷分离的有效策略。在此，使用缺电子的 4,4'-(噻唑并[5,4-]噻唑-2,5-二基)二苯甲醛（Tz）单元或 4,4'-(苯并[][1,2,5]噻二唑-4,7-二基)二苯甲醛（Td）单元和富电子的四(4-氨基苯基)乙烷（ETTA）连接体的两种供体-受体杂孔 COF 被呈现出来。所得的结晶性和杂孔 COF 在光照下表现出出色的过氧化物酶样活性，可催化典型底物的氧化以及相应的颜色和吸收变化。具有突出过氧化物酶样活性的可激活的 ETTA-Tz COF 可用作比色探针，用于定量检测硫离子，线性范围为 1-50 μM，检测限为 3 分钟内 0.27 μM。比色法也可用于人血清样品中硫离子的检测。该研究证明了完全共轭 COF 内 D-A 基序获得优异模拟酶活性的未来潜力。
