Thermolytic Synthesis of Imprinted Amines in Bulk Silica

The synthesis of bulk, hydrophilic imprinted silica is reported via a novel method relying on the thermolysis of carbamates. This method is used to synthesize single-site materials consisting of either isolated primary amines or multiple organized primary amines within an imprinted site. Materials are characterized by multinuclear solid-state NMR spectroscopy, high-resolution thermogravimetric analysis, and potentiometric titration. Diffuse-reflectance UV/Vis and solid-state fluorescence spectroscopies of probe molecule-bound materials are used to demonstrate the site-isolated and polar nature of the imprinted sites resulting from this process. The polar nature is due to hydrophilic silanol groups ingenerate to the framework of the material. These permit the partitioning of polar reagents, such as 1,3,5-trinitrobenzenesulfonic acid (TNBS), which are unable to access the imprinted sites when framework silanols are end-capped with hydrophobic trimethylsilyl functionality. The latter observation provides a mechanism to elucidate diminished reactivity of TNBS with lysine residues that are buried within the hydrophobic pocket of a protein.