Reactions of Amino Acids on the Si(100)-2 x 1 Surface

Reactions of amino acids on the Si(100)-2 X 1 surface have been investigated using the B3LYP hybrid density functional theory Amino acids provide a diverse set of organic functional groups, several of which have not been studied previously for their reactivity on semiconductor surfaces. The amino acid common group is found to react through several low energy pathways, with O-H dissociation of the carboxyl group being the most kinetically favorable. Consequently, reactions of amino acids through the amine and carboxyl functionalities are not expected to be selective. The reactivity of several of the amino acids displays unique, and possibly useful, properties not exhibited by organic functionalities previously considered, while others react on Si(100)-2 x 1 analogously to their simpler organic analogues. Resonance effects significantly affect the reaction energetics of arginine, histidine, and tryptophan leading to reactivities qualitatively different from their analogous isolated functional groups. The most unique of these reactivities include pericyclic ene reactions of the imine functional group of arginine and the cyclic imine of the imidazole side-chain of histidine. Both of these reactions involve formation of Si-N dipolar (dative) bonds which are significantly stronger than any previously observed on Si(100)-2 x 1.