Styryl-functionalized cage silsesquioxanes as nanoblocks for 3-D assembly

Herein we report the synthesis of a new family of styryl-functionalized polyhedral oligomeric silsesquioxanes (Tn, where n = 8, 10, and 12), in which the organic moiety is linked to all n vertices of the Tn cages via the phenyl ring rather than the vinyl group. In contrast to earlier studies in which the styryl group is linked to the cage via the vinyl moiety, our approach ensures that the vinyl moiety is less sterically hindered and available for postfunctionalization. The functional Tn cages have been characterized by a range of techniques, including single crystal X-ray diffraction, multinuclear solution NMR (1H, 13C, and 29Si), MALDI-MS, and FTIR. The solid-state structure of the T8 compound exhibited two nonequivalent Si8O12 cage atoms, which has not been previously reported in the functionalized T8 system, although all cage atoms in the corresponding T10 and T12 systems were equivalent. In contrast, multinuclear solution NMR data indicated that all cages in the T8 system were equivalent in solution, suggesting that the nonequivalent cage geometries arise in the solid state to optimize the packing of the functionalized cages. These compounds have significant potential for future use in the production of 3D cross-linked polymer networks.