Shape-selective binding in templated nanopores

IEC 38

Jessica L. Defreese and Alexander Katz. Department of Chemical Engineering, University of California at Berkeley, MC 1462, Berkeley, CA 94720-1462
Templated binding pockets have been synthesized via imprinting within a microporous silica framework. The synthetic approach uses a sol-gel process to co-condense a carbamate-based imprint with tetraethylorthosilicate to produce a hybrid organic-inorganic material. Cleavage of the carbamate linkage generates a primary amine within a templated pocket that is complementary to the size and shape of the imprint. Three imprints differing only in the side-chain functionality (methyl, ethyl, and propyl homologues) have been used to synthesize the templated silicates. The materials exhibit shape-selective binding of a-methylbenzyl isocyanate versus 1-(1-naphthyl)ethyl isocyanate in batch experiments. We unequivocally show that the selectivity of the isocyanate binding arises due to the size of the templated pocket. These results demonstrate the first shape-selective binding in imprinted silica, and repercussions to other systems will be discussed.