Molecular rotors in hierarchically ordered mesoporous organosilica frameworks

The remarkable dynamic behavior of highly ordered hexagonal mesoporous p-diphenylenesilicas is presented. Diphenylene moieties, aligned parallel along the pore walls, behave as molecular rotors and show a mobility with correlation times as short as a few nanoseconds. This results in an effectively ‘amphidynamic’ structure of the mobile hydrophobic diphenylene groups (rotors), which pivot on the more rigid hydrophilic silica species through covalent C–Si bonds. The structure is such that the diphenylene moieties are exposed to the interior pore spaces of the mesochannels. The intra-framework structure and motional behaviors of mesoporous diphenylene-silica are elucidated by solid-state multinuclear experiments and fast magic-angle spinning (MAS) 1H, 13C, and 29Si nuclear magnetic resonance (NMR) spectroscopy