Covalent organic frameworks have attracted considerable attention in recent years as a distinct class of crystalline porous organic materials. Their functional properties are inherently linked to their structural characteristics. Although hundreds of COFs have been reported so far, the types of their topologic structure are still limited. In this article, we report the identification of mcm topology for three porphyrin-based two-dimensional COFs, which are constructed from [4 + 4] imine condensation reactions. The mcm net is generated by pentagonal tiling, which has not been identified for COFs before. The structure of the COFs is elucidated by a variety of experimental characterization and structural simulations, by which their reticular frameworks exclusively composed of pentagonal pores have been confirmed. Moreover, the COFs exhibit high performance in photocatalytic hydrogen evolution from water, with the best one up to 10.0 mmol g⁻¹ h⁻¹ after depositing 0.76 wt% Pt as a co-catalyst. This study identifies mcm topology for COFs for the first time and highlights the potential of these COFs as promising photocatalysts for sustainable hydrogen production from water.

中文翻译：

---

mcm拓扑二维共价有机骨架的识别及其在光催化析氢中的应用


近年来，共价有机骨架作为一类独特的结晶多孔有机材料引起了人们的广泛关注。它们的功能特性与其结构特征有着内在的联系。尽管迄今为止已报道了数百种COF，但其拓扑结构的类型仍然有限。在本文中，我们报告了三种基于卟啉的二维 COF 的 mcm 拓扑结构的识别，这些 COF 由 [4 + 4] 亚胺缩合反应构建。 mcm 网是通过五边形平铺生成的，之前尚未针对 COF 进行识别。通过各种实验表征和结构模拟阐明了COF的结构，并证实了它们的网状框架完全由五边形孔组成。此外，COF在光催化水中析氢方面表现出高性能，在沉积0.76 wt% Pt作为助催化剂后，最好的析氢性能可达10.0 mmol g ⁻¹ h ⁻¹ 。这项研究首次确定了 COF 的 mcm 拓扑结构，并强调了这些 COF 作为有前途的光催化剂用于从水中可持续生产氢气的潜力。