Diphenylalanine-Derivative Peptide Assemblies with Increased Aromaticity Exhibit Metal-like Rigidity and High Piezoelectricity

Abstract

Diphenylalanine (FF) represents the simplest peptide building block that self-assembles into ordered nanostructures with interesting physical properties. Among self-assembled peptide structures, FF nanotubes display notable stiffness and piezoelectric parameters (Young’s modulus = 19–27 GPa, strain coefficient d 33 = 18 pC/N). Yet, inorganic alternatives remain the major materials of choice for many applications due to higher stiffness and piezoelectricity. Here, aiming to broaden the applications of the FF motif in materials chemistry, we designed three phenyl-rich dipeptides based on the β,β-diphenyl-Ala-OH (Dip) unit: Dip-Dip, cyclo-Dip-Dip, and tert-butyloxycarbonyl (Boc)-Dip-Dip. The doubled number of aromatic groups per unit, compared to FF, produced a dense aromatic zipper network with a dramatically improved Young’s modulus of ∼70 GPa, which is comparable to aluminum. The piezoelectric strain coefficient d 33 of ∼73 pC/N of such assembly exceeds that of poled polyvinylidene-fluoride (PVDF) polymers and compares well to that of lead zirconium titanate (PZT) thin films and ribbons. The rationally designed π–π assemblies show a voltage coefficient of 2–3 Vm/N, an order of magnitude higher than PVDF, improved thermal stability up to 360 °C (∼60 °C higher than FF), and useful photoluminescence with wide-range excitation-dependent emission in the visible region. Our data demonstrate that aromatic groups improve the rigidity and piezoelectricity of organic self-assembled materials for numerous applications.

Density functional theory predictions of the mechanical properties of crystalline materials

“…Using this methodology, we have calculated to a high accuracy versus experiment the elastic constants of amino acid 90,[98][99][100] and peptide crystals, 101,102 co-crystals, 103,104 and biominerals 105 (Fig. 2).…”

2D Layered Dipeptide Crystals for Piezoelectric Applications

“…However, it is smaller than that for tert ‐butyloxycarbonyl (Boc) protected dipeptide based on the β,β‐diphenyl‐Ala‐OH (2.75 Vm N −1 ) reported recently by Prof. Gazit's group. [ 92 ]…”

Advanced Methods for the Characterization of Supramolecular Hydrogels

“…While we sometimes rely on studies with a broader focus to be able to explain the techniques, in each section we include examples of how these methods have been used with supramolecular hydrogels to specifically illustrate the relevant information that can be obtained from this characterization. [14] with permission, ©2019-Royal Society of Chemistry; (b) from [15] under the terms of a CC-BY license, ©2014-American Chemical Society; (c) from [16] under the terms of the Creative Commons Attribution License, ©2014-the authors and published by Beilstein-Institut; (d) from [17] with permission, ©2019-Royal Society of Chemistry; (e) from [18] with permission, ©2017-Elsevier; and (f) from (i) [19] under the terms of a CC-BY license, ©2020-American Chemical Society and (ii) [20] under the terms of the Creative Commons Attribution License, ©2007-the authors and published by PLoS ONE.…”

“…Schematics of representative molecules from different classes of supramolecular hydrogelators showing the chemical structures and how they are hypothetically interacting to self-assemble, including (a) bis-urea derivatives, (b) nucleosides and nucleoside derivatives, (c) cavity-bearing molecules, (d) polyaromatic compounds, (e) saccharide derivatives, and (f) amino acids and peptides and their derivatives. The schematics of the self-assembled structures are reproduced (a) from[14] with permission, ©2019-Royal Society of Chemistry; (b) from[15] under the terms of a CC-BY license, ©2014-American Chemical Society; (c) from[16] under the terms of the Creative Commons Attribution License, ©2014-the authors and published by Beilstein-Institut; (d) from[17] with permission, ©2019-Royal Society of Chemistry; (e) from[18] with permission, ©2017-Elsevier; and (f) from (i)[19] under the terms of a CC-BY license, ©2020-American Chemical Society and (ii)[20] under the terms of the Creative Commons Attribution License, ©2007-the authors and published by PLoS ONE.…”