A covalently-linked microporous organic-inorganic hybrid framework containing polyhedral oligomeric silsesquioxane moieties

Abstract

By a Yamamoto-type of Ullmann cross-coupling reaction, a well-defined covalently-linked microporous organic-inorganic hybrid framework polyoctaphenylsilsesquioxane (JUC-Z1) was effectively prepared from the nano building block p-iodio-octaphenylsilsesquioxane (I8OPS) with a yield of ca. 100%. The structure of JUC-Z1 was characterized by ¹³C CP/MAS NMR and ²⁹Si MAS NMR experiments. Fourier transform infrared spectroscopy (FTIR) was performed to confirm the presence of functions in the framework. The results showed that inorganic silsesquioxane cubes were linearly covalently-linked by biphenyls, offering a highly cross-coupling framework. The powder X-ray diffraction (PXRD) pattern and transmission electron microscope (TEM) image show that JUC-Z1 is spherical with uniform micropores. N₂ adsorption results suggest that the hybrid framework has a narrow pore size distribution from 11.8 to 20.0 Å, with a BET surface area of 283 m²g⁻¹ and a pore volume of 0.226 cm³g⁻¹. A thermogravimetric (TG) analysis indicates the thermal stability of JUC-Z1 up to 397 °C in air. Moreover, a liquid sorption experiment reveals the favorable sorption of benzene and water.