Organosilicas with chiral bridges and self-generating mesoporosity

Amine-functionalized, chiral mesoporous organosilicas were prepared from a rationally designed precursor, which combines the functions of a network builder, a chiral latent functional group, and a porogen in one molecule. The precursors are formed by a convenient enantioselective hydroboration using (S)-monoisopinocampheylborane on an ethylene-bridged silica precursor. These precursors do self-organize when hydrolysis of their inorganic moiety takes place via an aggregation of their organic moiety into hydrophobic domains. After a condensation-ammonolysis sequence mesoporous organosilicas functionalized with chiral amine groups are obtained, with the complete chiral functionalities located at the pore wall surface and therefore accessible to chemical processes. The pore size of the resulting organosilicas can be fine-tuned using different organic moieties attached to the boron group in the first step. While a wormlike arrangement of pores is observed for the pure precursor, common surfactants can be admixed to further control and tailor the resulting mesoporous system. In certain phase ranges, also chiral periodic mesoporous organosilicas can be obtained.