Amino acid encapsulation in zeolite MOR: Effect of spatial confinement. Issue 36 (10th September 2021)

• Record Type: Journal Article
• Authors: Polisi, Michelangelo; Fabbiani, Marco; Vezzalini, Giovanna; Di Renzo, Francesco; Pastero, Linda; Quartieri, Simona; Arletti, Rossella
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 36(2021)
• Page Start: 20541
• Page End: 20552
• Publication Date: 2021-09-10
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp02676c
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The potential role of the zeolite in promoting peptide bond formation: Some molecules react to form either cyclic dimers or linear oligomers. Abstract : In this study the absorption of glycine, α-alanine and β-alanine amino acids into the pores of the synthetic zeolite Na-mordenite was investigated with the aim of: (i) evaluating the effectiveness of the MOR framework type in amino acid adsorption ( via vapor and aqueous loading); (ii) understanding the host–guest and guest–guest interactions to possibly design a tailor made material and a loading procedure able to maximize the amino acid adsorption; (iii) studying the effect of pressure on the adsorbed amino acids such as, for instance, possible amino acid condensation. The structural characterization, carried out with the combination of diffractometric and infrared spectroscopy analyses, shows that MOR can adsorb amino acids, which are found both in protonated/deprotonated (possibly also generating zwitterions) form. Vapor loading is ineffective for α-alanine, while it is effective in β-alanine and glycine adsorption, even if using different loading degrees. The shape and size of MOR channels make this zeolite suitable to accommodate a peptide. In a glycine loaded sample some molecules condensate to form cyclic dimers, while linear oligomers are detected only in a β-alanine MOR hybrid. The sample loaded with α-l -alanine from aqueous solution does not show the presence of amide bond signals, indicating that the molecules are mostly hosted in zwitterionic form in Na-MOR channels. The application of external baric stimuli does not induce substantial modifications in the structure of the glycine loaded zeolite; this result may be explained by the low number of molecules hosted in the channels. The amino acid amount within the zeolite pores is the most important reactivity parameter and an increased loading could induce chemical modifications.