Inversion of Supramolecular Chirality by Sonication-Induced Organogelation.

Sibaprasad Maity,Meital Reches,Priyadip Das

doi:10.1038/srep16365

Sibaprasad Maity, Meital Reches + Show 1 more

Open Access

https://doi.org/10.1038/srep16365

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Journal: Scientific reports	Publication Date: Nov 10, 2015
Citations: 36	License type: CC BY 4.0

Affiliation: Hebrew University of Jerusalem

Abstract

Natural helical structures have inspired the formation of well-ordered peptide-based chiral nanostructures in vitro. These structures have drawn much attention owing to their diverse applications in the area of asymmetric catalysts, chiral photonic materials, and nanoplasmonics. The self-assembly of two enantiomeric fluorinated aromatic dipeptides into ordered chiral fibrillar nanostructures upon sonication is described. These fibrils form organogels. Our results clearly indicate that fluorine-fluorine interactions play an important role in self-assembly. Circular dichroism analysis revealed that both peptides (peptides 1 and 2), containing two fluorines, depicted opposite cotton effects in their monomeric form compared with their aggregated form. This shows that supramolecular chirality inversion took place during the stimuli-responsive self-aggregation process. Conversely, peptide 3, containing one fluorine, did not exhibit chirality inversion in sonication-induced organogelation. Therefore, our results clearly indicate that fluorination plays an important role in the organogelation process of these aromatic dipeptides. Our findings may have broad implications regarding the design of chiral nanostructures for possible applications such as chiroptical switches, asymmetric catalysis, and chiral recognitions.

Highlights

Helicity creates chiral motifs in numerous biomolecular structures
All dipeptides were synthesized by a solution phase method, as described in our previous report (Supplementary Information)[37]
The observed Tgel temperature for the gel formed by peptide 3 was 41 °C–43 °C, which is comparatively lower than the Tgel values observed for peptides 1 and 2

Summary

Introduction

Helicity creates chiral motifs in numerous biomolecular structures. Two common helical structures are (1) the α -helix, a secondary structure of proteins, and (2) the double helix formed by the two strands of DNA1,2. We report, for the first time, the inversion of chirality by fluorinated peptide-based gelators that contain two fluorine atoms, upon sonication-induced organogelation. Peptides 1, 2, and 3 formed organogels in a hexane-ethyl acetate mixture (3:1 v/v) or toluene.

Results

Conclusion