Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong, China.
School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou, 510006 Guangdong, China.
Inorg Chem. 2022 Sep 12;61(36):14352-14360. doi: 10.1021/acs.inorgchem.2c02135. Epub 2022 Aug 26.
The useful yet underutilized backfolded design is invoked here for functionalizing porous solids with the versatile carbazole function. Specifically, we attach carbazole groups as backfolded side arms onto the backbone of a linear dicarboxyl linker molecule. The bulky carbazole side arms point away from the carboxyl links and do not disrupt the Zr-carboxyl framework formation; namely, the resultant MOF solid Zr features the same net as that of the unfunctionalized dicarboxyl linker, also known as the PCN-111 net or UiO-66 net. The Zr structure features only half linker occupancy (about 6 out of the 12 linkers around the ZrO cluster being missing) and partially collapses upon activation (acetone exchange and evacuation). Notably, the stability improves after heating in diphenyl oxide at 260 °C (POP-260 treatment; to form Zr-260), as indicated by the higher crystallinity and surface area of the activated Zr-260 sample. The Zr-260 samples achieve 72% yield in photocatalyzing reductive dehalogenation of phenacyl bromide; Zr can detect nitro-aromatic compounds via fluorescence quenching, with selectivity and sensitivity toward 4-nitroaniline, featuring a limit of detection of 96 ppb.
这里引入了一种有用但未充分利用的背折叠设计，以便用多功能咔唑官能团功能化多孔固体。具体来说，我们将咔唑基团作为背折叠侧臂连接到线性二羧酸 linker 分子的主链上。庞大的咔唑侧臂远离羧基链接指向，不会破坏 Zr-羧基框架的形成；也就是说，所得 MOF 固体 Zr 具有与未官能化的二羧酸 linker 相同的 net，也称为 PCN-111 net 或 UiO-66 net。Zr 结构仅具有一半的 linker 占有率（ZrO 簇周围的 12 个 linker 中有大约 6 个缺失），并且在活化时部分坍塌（丙酮交换和抽空）。值得注意的是，在 260°C 的二苯氧化物中加热（POP-260 处理；形成 Zr-260）后稳定性提高，这表明活化的 Zr-260 样品具有更高的结晶度和表面积。Zr-260 样品在光催化还原脱卤化苯乙酮溴化物中实现了 72%的产率；Zr 可以通过荧光猝灭检测硝基芳香族化合物，对 4-硝基苯胺具有选择性和灵敏度，检测限为 96 ppb。
