Hydrolysis of Glucans Grafted On Inorganic Oxides: Role of OH-Defect Sites

We describe the first example of OH-defect-site catalysis in water, with the hydrolysis of grafted glucans on silica and alumina.  Catalytic comparisons between these two systems demonstrate that the key feature that controls hydrolysis activity is OH-defect site density on the surface, both during glucan anchoring as well as during hydrolysis catalysis.  The latter enforces a high local density of defect sites, which act as an array to activate glycosidic oxygens that are constrained to be near the surface for hydrolysis catalysis.  This result has significant repercussions on understanding other weak-acid site catalysts for glucan hydrolysis such as unfunctionalized carbon.