德国德累斯顿工业大学Stefan Kaskel团队开发了用于湿度控制应用，具有酸变色响应的化学稳定的咔唑基亚胺共价有机框架。相关研究成果于2021年11月2日发表在国际顶尖学术期刊《美国化学会杂志》。

研究人员在4,4′-双（9H-咔唑-9-基）联苯四醛与苯二胺和联苯胺的反应中获得化学稳定的等网状二维亚胺共价有机框架（COFs），分别表示为DUT-175和DUT-176。根据粉末X射线衍射数据解析和细化的晶体结构，并经高分辨率透射电子显微镜确认，表明其为AA叠层结构。两种结构均具有扭曲的六边形通道孔，确保显著的孔隙率（对于DUT-175，SBET=1071 m² g^–1，对于DUT-176，SBET=1062 m² g^–1），该结果通过气体和蒸汽的吸附得到确认。

COFs的复杂共轭π系统涉及富含电子的咔唑构建单元，它与亚胺基团结合使框架可逆的pH依赖性质子化，并伴随着紫外-可见光谱中的电荷转移和吸收带移动。水蒸气吸附和解吸等温线呈S形，在p/p₀=0.4–0.6时具有陡峭的吸附过程，再加上在数十次吸附和解吸循环中具有优异的稳定性，将该COFs列为室内湿度控制应用的最佳材料。

附：英文原文

Title: Chemically Stable Carbazole-Based Imine Covalent Organic Frameworks with Acidochromic Response for Humidity Control Applications

Author: Leisan Gilmanova, Volodymyr Bon, Leonid Shupletsov, Darius Pohl, Marcus Rauche, Eike Brunner, Stefan Kaskel

Issue&Volume: November 2, 2021

Abstract: Isoreticular chemically stable two-dimensional imine covalent organic frameworks (COFs), further denoted as DUT-175 and DUT-176, are obtained in a reaction of 4,4′-bis(9H-carbazol-9-yl)biphenyl tetraaldehyde with phenyldiamine and benzidine. The crystal structures, solved and refined from the powder X-ray diffraction data and confirmed by high-resolution transmission electron microscopy, indicate AA-stacked layer structures. Both structures feature distorted hexagonal channel pores, assuring remarkable porosity (SBET = 1071 m2 g–1 for DUT-175 and SBET = 1062 m2 g–1 for DUT-176), as confirmed by adsorption of gases and vapors. The complex conjugated π system of the COFs involves electron-rich carbazole building units, which in combination with the imine groups allow reversible pH-dependent protonation of the frameworks, accompanied by charge transfer and shift of the absorption bands in the UV–vis spectrum. The sigmoidal shape of the water vapor adsorption and desorption isotherms with a steep adsorption step at p/p0 = 0.4–0.6 in combination with excellent stability over dozens of adsorption and desorption cycles ranks these COFs among the best materials for indoor humidity control applications.

DOI: 10.1021/jacs.1c07148

Source: https://pubs.acs.org/doi/10.1021/jacs.1c07148