Presentation Title

Enantiomeric interactions of amino acids adsorbed in zeolites: An investigation using Solid-State NMR and Molecular Modelling

Start Date

November 2016

End Date

November 2016

Location

HUB 268

Type of Presentation

Oral Talk

Abstract

In the past years we studied zeolites as a medium for enriching the enantiomeric excess of solutions. Zeolite being achiral, do not prefer one enantiomer over the other. However, if the D- and L- enantiomers adsorb together as a heterodimer, the enantiomeric excess of the solution they leave behind is augmented. We used NMR to explore the adsorption behaviors of D-, L-, and DL- N-acetyl Leucine, Alanine and Methionine into Zeolite NaY. The solid state NMR spectra of the pure D- and L- acetyl Leucine showed the same results as the racemic mixture of N-acetyl-DL-Leucine, indicating a preference to form microcrystals of pure D and L forms. In contrast differences in the solid state NMR spectra are observed for N-Acetyl -DL- Methionine and N-acetyl-DL -Alanine from their pure enantiomers. This implied that both form a mixed crystal. However when adsorbed onto the zeolite, N-Acetyl Methionine and N-acetyl-Alanine exhibit the same behavior as its Leucine counterpart indicating that they are adsorbed as homodimers. Recently, in order to investigate this behavior further we decided to study the same set of systems with molecular modelling. As a starting point, considering only Van der Waals interactions, we investigated how these amino acids were fitting into the zeolite cage. We found that Alanine gets adsorbed better than Leucine and Methionine. We are in the process of implementing the effect of electrostatics in our simulations. We will present the results of computer simulations regarding the dynamics and energetics of the enantiomer-zeolite interactions.

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Nov 12th, 3:30 PM Nov 12th, 3:45 PM

Enantiomeric interactions of amino acids adsorbed in zeolites: An investigation using Solid-State NMR and Molecular Modelling

HUB 268

In the past years we studied zeolites as a medium for enriching the enantiomeric excess of solutions. Zeolite being achiral, do not prefer one enantiomer over the other. However, if the D- and L- enantiomers adsorb together as a heterodimer, the enantiomeric excess of the solution they leave behind is augmented. We used NMR to explore the adsorption behaviors of D-, L-, and DL- N-acetyl Leucine, Alanine and Methionine into Zeolite NaY. The solid state NMR spectra of the pure D- and L- acetyl Leucine showed the same results as the racemic mixture of N-acetyl-DL-Leucine, indicating a preference to form microcrystals of pure D and L forms. In contrast differences in the solid state NMR spectra are observed for N-Acetyl -DL- Methionine and N-acetyl-DL -Alanine from their pure enantiomers. This implied that both form a mixed crystal. However when adsorbed onto the zeolite, N-Acetyl Methionine and N-acetyl-Alanine exhibit the same behavior as its Leucine counterpart indicating that they are adsorbed as homodimers. Recently, in order to investigate this behavior further we decided to study the same set of systems with molecular modelling. As a starting point, considering only Van der Waals interactions, we investigated how these amino acids were fitting into the zeolite cage. We found that Alanine gets adsorbed better than Leucine and Methionine. We are in the process of implementing the effect of electrostatics in our simulations. We will present the results of computer simulations regarding the dynamics and energetics of the enantiomer-zeolite interactions.