Designed Synthesis And Morphology/Mesostructure Control Of Chiral Norbornane-Bridged PMO Materials

Embedding the bridging organic group R within the framework efficiently and uniformly, periodic mesoporous organosilica (PMO) materials are elaborately constructed by the self-assembly of bis-alkoxysilane (R’O)3Si-R-Si(OR’)3precursors. Due to the combined advantages of the ordered mesoporous structure and controlled morphology, this new type of organic-inorganic hybrid mesoporous materials is of potential importance in various fields, and receiving much research interest. Though tremendous attention has been paid to the morphology-and mesostructure-controlled synthesis of PMOs based on the small bridged groups, such as ethane, ethylene and benzene, the morphology-and mesostructure-controlled synthesis of chiral PMO has not been reported.On the other hand, increasing attention has been paid to chiral PMO materials, which are potentially applicable in heterogeneous asymmetric catalysis and chiral separation. Our group has reported the facile synthesis of a novel chiral norbornane-bridged Precursor1,(lR,2S,4R,5S)-exo,exo-2,5-bis(trimethoxysilyl)-bicyclo[2,2,1]heptane. A highly-ordered chiral PMO was successfully synthesized via the self-condensation of this chiral precursor. Based on our previous work, we report herein the designed synthesis and morphology/mesostructure control of chiral norbornane-bridged PMO materials.In Chapter III, we report the synthesis of Precursor2,(1R,2S,4R,5S)-exo,exo-2,5-bis(triethoxysilyl)bicyclo[2,2,1]heptanes. Using Precursor2, the morphology-controlled synthesis of norbornane-bridged chiral PMOs was conducted by adding co-solvent, inorganic salts, or a combination of co-solvent and inorganic salts.In Chapter IV, chiral PMO materials with three-dimensional body-centered (Im3m) and face-centered (Fm3m) cubic mesostructures were first synthesized from the self-condensation of chiral Precursor1under acidic conditions. With triblock copolymer F127as a template, an Im3m type chiral PMO with spherical morphology was obtained. Meanwhile, an Fm3m type chiral PMO with special pumpkin-like morphology was prepared in the presence of a co-structure directing agent (triblock copolymer P123and Gemini surfactant C14-6-14). In Chapter V, the synthesis and catalytic performance of chiral Pd-PMO material was investigated. In Chapter VI, we designed a synthetic route to chiral Precursor4,(1R,4R)-2,5-bis(triethoxysilyl)-bicyclo[2,2,1]hepta-2,5-diene.