Investigating the interactions of the enantiomers of phenylglycine with nanopores of ZSM-5 zeolite

Abstract

In this study, molecular dynamics simulation has been used to investigate the interactions of both chiral forms of phenylglycine amino acid (R- and S-isomers) with micropores of ZSM5-zeolite. Calculated results show that phenylglycine molecules interact with zeolite surface by electrostatic interaction of their positively charged ammonium group and negatively charged carboxylic group. This leads to the formation of two hetero hydrogen bonds between amino groups and oxygen of zeolite framework and also one hydrogen bond between the carboxylic groups and the zeolite surface. Further analyses show that S-isomers have stronger interactions with zeolite surface in comparison to R-isomers. So, movement, radius of gyration and angle of orientation of S-isomers inside nanopores are decreased, while R-isomers interact more strongly with each other. However, both chiral forms have diffusive behaviour along the pores with the self diffusion coefficient of about two orders of magnitude less than that in free water. © 2014 Indian Academy of Sciences.