Polymorphism of asymmetric catalysts based on amphiphilic lipopeptides in solution

Pelin, J. N. B. D., Edwards-Gayle, C. J. C., Aguilar, A. M., Kaur, A., Hamley, I. W. ORCID: https://orcid.org/0000-0002-4549-0926 and Alves, W. A. (2020) Polymorphism of asymmetric catalysts based on amphiphilic lipopeptides in solution. Soft Matter, 16 (19). pp. 4615-4624. ISSN 1744-683X doi: 10.1039/D0SM00245C

Abstract/Summary

The self-assembly of model [P]RWG lipopeptides (P: L-proline, R: L-arginine, W: L-tryptophan, G: L-glycine), containing one or two aliphatic octadecyl (C18) chains in water and cyclohexanone/water solutions was examined. The self-assembly of mixtures of these RWG and PRWG lipopeptides was also investigated. These materials presented a similar critical aggregation concentration of ∼4.0 × 10−4 wt% and were characterized by unordered secondary structures with some β-sheet content. TEM and cryo-TEM revealed the presence of mainly nanotape structures with micelles observed for systems rich in PRWG(C18H37). Analysis of detailed SAXS form factor measurements revealed the presence of bilayers 3–4 nm thick while the PRWG(C18H37) micelles have a core radius of approximately 3 nm, and a shell thickness of 2 nm. For the cyclohexanone/water systems polymorphs containing cluster aggregates (with radius of 0.25 nm to 0.50 nm) and some elongated structures (with radius of 5.7 nm to 26.1 nm) were seen. Longer structures were formed with the increase of the proline-containing lipopeptide content. The catalytic activity of these peptides was assessed using a model nitro-aldol reaction. The concentration of water in the reaction system influenced the conversion, higher content promoted better efficiency for the water systems, but the opposite was observed for the cyclohexanone/water samples.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/90611
Item Type	Article
Refereed	Yes
Divisions	Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	Royal Society of Chemistry
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