Development of a robust supramolecular method to prepare well-defined nanofibrils from conjugated molecules

Abstract

In order to produce materials with tailored structures and functions via supramolecular self-assembly of molecular precursors in a predictable fashion, it is necessary to develop 'supramolecular methods' based on structurally simple 'supramolecular synthons'. Thus, the formation of one-dimensional aggregates from p-conjugated molecules requires a combination of non-covalent interactions that efficiently suppresses lateral aggregation, promotes one-dimensional aggregation, and is also compatible with a productive p-p overlap of the constituent molecules. In the present work, we demonstrate that oligopeptide-polymer derivatives comprising a flexible polymer segment terminally attached to a b-sheet-forming oligopeptide segment are structurally simple substituents that perfectly fulfill these requirements. We synthesized a matrix of diacetylene model compounds that carried oligopeptide-polymer substituents with varying degrees of polymerization of the attached polymers and different length oligopeptide segments. We combined solution-phase IR spectroscopy, AFM imaging and the topochemical diacetylene polymerization as a highly sensitive probe for the molecular arrangement and the degree of order inside aggregates obtained in organic solvents. The thus determined molecular parameters for the reliable formation of well-defined nanoscopic fibrillar structures with uniform diameters, and defined helical 'core-shell' morphologies were then successfully transferred to analogous perylene bisimide and quaterthiophene derivatives, demonstrating the versatility and robustness of the chosen molecular design.

A toolbox of oligopeptide-modified polymers for tailored elastomers

“…In this way, the versatile properties of different types of silk materials are precisely tailored according to their function [11][12][13] . Inspired by this example of nature's design principles, the selective formation of onedimensional nanostructures from b-sheet-forming oligopeptides and oligopeptide-modified polymers has been extensively investigated [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] . However, the thermomechanical properties of the corresponding bulk materials have rarely been studied in much detail [29][30][31] .…”

Polydiacetylene‐Peptide 1D Nanomaterials

“…An amino acid sequence is chosen that will preferentially form β ‐sheets (in this case, parallel β ‐sheets) with stabilizing hydrogen bonds being formed between adjacent chains. The final feature is a terminal end group (green) that further directs nanostructure formation through hydrogen bonding NHAc and oligopeptide motifs as well as π‐stacking Fmoc units . This molecular architecture acts as a “supramolecular synthon” where the individual segments of a single molecule are specifically designed to cooperatively direct the formation of well‐defined nanostructures .…”

Peptide‐Thiophene Hybrids as Self‐Assembling Conductive Hydrogels

“…Previous studies have shown that peptides with as few as four amino acid residues can assemble into fibrous gels that mimic the structure of soft tissues, giving rise to hybrid materials that are viable for in vivo applications . Peptide‐hybrids containing conjugated thiophene or phenylene oligomers have been analyzed and shown to form canonical structures based upon the amino acid sequence of the peptide, resulting in fibrillar structures with unique optical properties . Composites containing peptide assemblies and CPs such as polyacetylene and poly(3,4‐ethylenedioxythiophene) (PEDOT) derivatives have also been reported, but bulk hydrogel structure, mechanical and electrical properties have yet to be investigated in detail.…”