Footprint Catalysis VII. Reinvestigation of the Imprinting Procedures for Molecular Footprint Catalytic Cavities: The Effects of Imprinting Procedure Temperature on the Catalytic Characteristics

The authors’ imprinting procedures for “molecular footprint” catalytic cavities on a silica (alumina) gel surface were reinvestigated. The increases of temperature during the incorporation of aluminum ions into the silicate matrix and during the footprint-imprinting with a template remarkably affected the catalytic characteristics of the resulting cavities. A change from room temperature to 75—80 °C increased the catalytic specificities (kcat/Km) by a factor of nearly 50. The results also provided experimental proof for the speculated mechanism of footprint formation. That is, the imprinting comprises precedent Lewis acid site generation on a silicate surface and subsequent Lewis acid–template complexation. The resulting acid–template complexes give rise to the footprint cavities upon removal of the template.