  Microporous organosilicas assembled from polysilsesquioxane (POSS) building
blocks are promising materials that are yet to be explored in-depth. Here, we
investigate the processing and molecular structure of bispropylurea bridged
POSS (POSS-urea), synthesised through the acidic condensation of
1,3-bis(3-(triethoxysilyl)propyl)urea (BTPU). Experimentally, we show that
POSS-urea has excellent functionality for molecular recognition toward
acetonitrile with an adsorption level of 74 mmol/g, which compares favourably
to MOFs and zeolites, with applications in volatile organic compounds (VOC).
The acetonitrile adsorption capacity was 132-fold higher relative to adsorption
capacity for toluene, which shows the pores are highly selective towards
acetonitrile adsorption due to their size and arrangement. Theoretically, our
tight-binding density functional and molecular dynamics calculations
demonstrated that this BTPU based POSS is microporous with an irregular
placement of the pores. Structural studies confirm maximal pore sizes of around
1 nm, with POSS cages possessing an approximate edge length of approximately
3.16 Angstrom
