Folding properties, molecular recognition and aggregation behavior of aromatic oligoamide helical capsules in water

Teng, Binhao (2023): Folding properties, molecular recognition and aggregation behavior of aromatic oligoamide helical capsules in water. Dissertation, LMU München: Fakultät für Chemie und Pharmazie

Abstract

A foldamer is a discrete chain molecule (oligomer) in chemistry that folds into a conformationally ordered state in solution. Local conformation preference is primarily responsible for the well-folded structure, however, hydrophobic effects also play a significant part in the folding process. As the secondary and tertiary structures of biomacromolecules have shown biological activity, the distinct aggregation patterns of foldamers that led to complex structures are significant. It may also result in the development of novel chemical or biological activities. Narrow helical foldamers have been intensively studied over the past decade, but a strategy for rapidly achieving a large cavity helix is still urgently required. The new building blocks not only alter the geometry of foldmers but also their aggregation behaviors; additionally, the novel features brought by the enormous diameter require additional investigation. This study introduces a novel class of aromatic δ-amino acid foldamers based on 7-amino-2-quinolinecarboxylic acid (QH). It was proved that these more flexible units may be folded well-ordered with more than two helical turns in water, with the stability increasing as the length of the main chain grew. The hydrophobic effects have a significant impact on the folding process; hence, the QH unit could not be folded in DMSO. In addition, a number of unique dimerization patterns (head-to-head, parallel double helix, and potential tetrameric helix) were discovered by altering the side chains, which may be attributed to electron repulsion and desolvation effect. Thus, these observations enable designs that enlarge the capsule cavity without modifying the capsule's backbone. In aqueous solution, the study discusses the discovery of a binding affinity between water-soluble guests and amphiphilic hosts. Due to the release of highly ordered water in the cavity, an unusual endothermic binding process that was entirely driven by entropy was observed. This particular molecular recognition can be utilized for molecular separation and reaction containers. In conclusion, our findings constitute a significant reference for the backbone flexible sequence helical folding and the construction of large cavity foldamers for guest binding in aqueous media. In addition, various aggregation patterns and the first capsule crystal grown in water were observed. The solid state and cavity binding affinity research could serve as a starting point for future designs and help develop several different capsules for specific purposes.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 500 Naturwissenschaften und Mathematik ; 500 Naturwissenschaften und Mathematik > 540 Chemie
• Fakultäten: Fakultät für Chemie und Pharmazie
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 23. Juni 2023
• 1. Bericht­erstatter:in: Huc, Ivan