江东林Angew：结晶多孔8字形节点COFs

本文要点：

1. 八字大环代表了一类引人入胜的π共轭单元，其特点是独特的美学和中心的非接触分子交叉。尽管合成技术在过去的一个世纪里取得了进步，但对无机、有机和聚合物8字形材料的研究仍处于起步阶段。

2. 在这里，作者报告了第一个8字形共价有机框架的例子，通过压缩8字形结来创建扩展的多孔8字形π结构。一个明显的特征是聚合将数字8结交织成双层，在超分子聚合后，这些双层组织了明确的层框架。

3. 8字形框架显示出2.3 eV的带隙，并发出明亮的橙色荧光，具有基准量子产率。值得注意的是，在光照下，供体-受体8字形骨架将8字形结转化为还原中心，连接体转化为氧化位点，使电荷通过π柱传输和积累，而内置的亲水微孔允许通过毛细管效应快速输送水和氧。

4. 有了这些独特的特征，8字形框架就像光催化剂一样，以水/盐水、氧气/空气和光作为唯一的输入，以高速率和高效率产生过氧化氢。

5. 这项工作为一类新的分子框架铺平了道路，为研究定义明确的8字形材料奠定了基础，以探索迄今为止我们尚未触及的前所未有的结构和功能。

Figure 1. Design and synthesis of figure-eight COF. a, Schematic for the synthesis of Imide-[8]pcpt-Pyr-COF from figure-[8] knot [8]pcpt and Pyr linker. b, Chemical structure of Imide-[8]pcpt-Pyr-COF. c and d, Top (c) and side (d) views of reconstructed Imide-[8]pcpt-Pyr-COF (grey: C; blue: N; red: O; white: H).

Figure 2. Characterization. a, FT IR spectra of Imide-[8]pcpt-Pyr-COF (red curve), [8]ptct (blue curve) and Pyr (black curve). b, Solid-state 13C CP/MAS of Imide- [8]pcpt-Pyr-COF; star: side peaks. c, Experimentally obtained PXRD patterns (blue cross), Pawley refined pattern (red curve), their differences (black curve), and simulated AA stacking pattern (green curve). d, N2 sorption isotherm curves (filled dot: adsorption; open dot: desorption). e, Pore size (open dot) and pore volume (filled dot). f, FE SEM image. g, Low-resolution TEM. h, HR TEM image. i, FFT profile of TEM image. j, AFM images of Imide-[8]ptct-Pyr-COF dispersed in EtOH. k, corresponding height profile along the red line. l, Water vapour sorption isotherms of Imide-[8]ptct-Pyr-COF at 298 K (solid dot, adsorption; open dot, desorption). m, Contact angle test for Imide-[8]ptct-Pyr-COF.

Figure 3. Absorption and luminescence. a, Solid-state electronic absorption spectra of Pyr (black), [8]pcpt (blue), and Imide-[8]pcpt-Pyr-COF (red). b, Tauc plots of Pyr (black), [8]pcpt (blue), and Imide-[8]pcpt-Pyr-COF (red). c, Fluorescence spectra of [8]pcpt (blue), Pyr (black), and Imide-[8]pcpt-Pyr-COF (red). d, Fluorescence decay profile of Pyr (black), [8]pcpt (blue), and Imide-[8]pcpt-Pyr-COF (red). e, Absolute fluorescence quantum yield of [8]pcpt (blue) and Imide-[8]pcpt-Pyr-COF (red). f, Fluorescence lifetime of [8]pcpt (blue) and Imide-[8]pcpt-Pyr-COF (red). g, Electronic absorption spectra of Imide-[8]pcpt-Pyr-COF dispersed in solvent. h, Fluorescence spectra of Imide-[8]pcpt-Pyr-COF dispersed in solvent. i, Fluorescence spectral change of Imide-[8]pcpt-Pyr-COF upon addition of water. j Fluorescence intensity change of Imide-[8]pcpt-Pyr-COF upon addition of water.

Figure 4. Photo properties and photocatalysis. a, The CV curve of Imide-[8]pcpt-Pyr-COF. b, Energy band alignment. c, Photocurrent density of [8]pcpt (blue curve) and Imide-[8]pcpt -Pyr-COF (red curve). d, Electrochemical impedance spectra (open circle, in the dark; solid circle, under visible light irradiation; blue, [8] pcpt; red, Imide-[8]pcpt -Pyr-COF). e, Photocatalytic production of H2O2 by Imide-[8]pcpt -Pyr-COF (O2; red curve: water; blue: water/EtOH (9/1); sky blue: water/MeOH (9/1); deep blue: NaCl solution (3 wt%)). f, Photocatalytic H2O2 production rate in the presence of alcohols. g, Electronic absorption spectrum (blue) and apparent quantum efficiency (red). h, Photocatalytic H2O2 production rate in the presence of scavengers (N.D.: not detected). i, Photoinduced electron transfer and catalytic sites (C1 and C2) for oxygen reduction and water oxidation. j, Gibbs free energy diagram for the oxygen reduction reaction over C1 and C2 sites (sky blue circle) of the Pyr linker. k, Gibbs free-energy diagram for the oxygen evolution reaction over phenyl site (red circle) of the [8]pcpt knot.  

https://doi.org/10.1002/anie.202425103