Silicon and oxygen are the two most abundant elements in the Earth’s crust. One important configuration of these two elements is a siloxanol (ROSiOH), a motif capable of hydrogen bonding that is found in various materials including the surface of silica gel. Hydrogen bonding dictates important binding interactions for various materials and molecules. Understanding how varying arrangements of hydrogen-bonding functional groups interact with small molecules can provide insights for designing materials, catalysts, and drugs. Investigating the hydrogen-bonding behavior of siloxanols can lead to a better understanding of their role in the applications of silica gel in separations, material science, heterogeneous catalysis, and drug delivery. In this study, a series of polyhedral oligomeric silsesquioxane (POSS) triols, R7Si7O9(OH)3, an inorganic-organic hybrid structure containing siloxanol groups, are used as soluble model compounds to study their hydrogen-bonding interactions. NMR spectroscopy was used to probe solution-phase molecular hydrogen-bonding interactions of POSS triols with neutral and anionic Lewis bases. Various POSS siloxanol derivatives have been designed and synthesized to compare binding interactions and catalytic activity in a Friedel-Crafts addition of indole to nitrostyrene. These results provide insight into which siloxanol arrangements can provide effective hydrogen-bonding activation and serve as useful models of silica materials.

Exploring hydrogen bonding of silica materials using a soluble organosilicon model compound

256th National Meeting (2018)

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