Redox‐Active Peptide‐Functionalized Quinquethiophene‐Based Electrochromic π‐Gel

Abstract

An electrochromic system based on a self-assembled dipeptide-appended redox-active quinquethiophene π-gel is reported. The designed peptide-quinquethiophene consists of a symmetric bolaamphiphile that has two segments: a redox-active π-conjugated quinquethiophene core for electrochromism, and peptide motif for the involvement of molecular self-assembly. Investigations reveal that self-assembly and electrochromic properties of the π-gel are strongly dependent on the relative orientation of peptidic and quinquethiophene scaffolds in the self-assembly system. The colors of the π-gel film are very stable with fast and controlled switching speed at room temperature.

Self-Assembling Peptidic Bolaamphiphiles for Biomimetic Applications

“…Konda et al prepared an electrochromic hydrogel from bola 29, a quinquethiophene derivative with dileucine units (Figure 21a,b). 184 The dileucine units led to the stacking of quinquethiophene in the J-aggregation conformation through the hydrogen bonding between the amide bonds. The stacked thiophene units exhibited electrochromism where the color changes with the oxidation state of the quinquethiophene backbone.…”

“…Thiophene is a well-known π-conjugated polymer displaying diverse colors with the oxidation state. Konda et al prepared an electrochromic hydrogel from bola 29 , a quinquethiophene derivative with dileucine units (Figure a,b) . The dileucine units led to the stacking of quinquethiophene in the J-aggregation conformation through the hydrogen bonding between the amide bonds.…”

“…(h) Structure of bola 33 . Part b is reproduced with permission from ref . Copyright 2018, John Wiley and Sons.…”

Patchy Particle Model of the Hierarchical Self-Assembly of π-Conjugated Optoelectronic Peptides

“…Oligopeptides containing embedded π-conjugated subunits within the backbone have emerged as a valuable class of easily synthesized, biocompatible building blocks for triggerable self-assembly into micron-size β-sheet-like aggregates driven by hydrophobicity, π-stacking, and hydrogen bonding interactions. − Electronic delocalization between overlapping π-orbitals, proton transfer along hydrogen bonds, and potentially other more complex electronic effects endow the supramolecular aggregates with emergent optical and electronic properties including fluorescence, electron transport, and exciton migration that make them attractive candidates for bioelectronic applications such as photovoltaics, energy harvesting and transport, biosensors, transistors, and light-emitting diodes. ,− The chemical diversity of peptide sequences and conjugated core chemistriestogether with their water solubility, biocompatibility, and ease of synthesisrenders π-conjugated oligopeptides highly tunable building blocks that can be manipulated to control emergent structure and function. ,,,,− …”