Cheng Shengxian, Tieu Peter, Gao Wenpei, Hu Jieying, Feng Weijin, He Jun, Pan Xiaoqing, Xu Zhengtao
Department of Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China.
Dalton Trans. 2020 Sep 14;49(34):11902-11910. doi: 10.1039/d0dt02075c. Epub 2020 Aug 18.
We report a curious case study of a Zr(iv)-carboxylate framework, which retains significant crystalline order after cascade thermocyclization of its linker components, and - more notably - after the crucial carboxylate links were severed by heat. Vigorous heat treatment (e.g., 450 °C and above) benzannulates the multiple alkyne groups on the linker to generate linked nanographene blocks and to afford real stability. The resultant Zr oxide/nanographene hybrid solid is stable in saturated NaOH and concentrated HPO, allowing a convenient anchoring of HPO into its porous matrix to enable size-selective heterogeneous acid catalysis. The Zr oxide components can also be removed by strong hydrofluoric acid to further enhance the surface area (up to 650 m g), without collapsing the nanographene scaffold. The crystallinity order and the extensive thermal transformations were characterized by X-ray diffraction, scanning transmission electron microscopy (STEM), IR, solid state NMR and other instrumental methods.
我们报告了一个关于锆（IV）羧酸盐框架的奇特案例研究，该框架在其连接体组件进行级联热环化后，更值得注意的是在关键的羧酸盐连接被热切断后，仍保留了显著的晶体有序性。剧烈的热处理（例如450°C及以上）使连接体上的多个炔基发生苯并环化，生成连接的纳米石墨烯块并提供真正的稳定性。所得的氧化锆/纳米石墨烯混合固体在饱和氢氧化钠和浓磷酸中稳定，便于将磷酸锚定到其多孔基质中以实现尺寸选择性多相酸催化。氧化锆组分也可以用强氢氟酸去除，以进一步增加表面积（高达650 m²/g），而不会使纳米石墨烯支架坍塌。通过X射线衍射、扫描透射电子显微镜（STEM）、红外光谱、固态核磁共振和其他仪器方法对结晶顺序和广泛的热转变进行了表征。
