Revealing the Sequence-Structure-Electronic Property Relation of Self-Assembling π-Conjugated Oligopeptides by Molecular and Quantum Mechanical Modeling

Bryce A. Thurston, Ethan P. Shapera, John D. Tovar, André Schleife, Andrew L. Ferguson

Research output: Contribution to journalArticle

Abstract

Self-assembled nanoaggregates of π-conjugated synthetic peptides present a biocompatible and highly tunable alternative to silicon-based optical and electronic materials. Understanding the relationship between structural morphology and electronic properties of these assemblies is critical for understanding and controlling their mechanical, optical, and electronic responses. In this work, we combine all-atom classical molecular simulations with quantum mechanical electronic structure calculations to ascertain the sequence-structure-electronic property relationship within a family of Asp-X-X-quaterthiophene-X-X-Asp (DXX-OT4-XXD) oligopeptides in which X is one of the five amino acids {Ala, Phe, Gly, Ile, Val} ({A, F, G, I, V}). Molecular dynamics simulations reveal that smaller amino acid substituents (A, G) favor linear stacking within a peptide dimer, whereas larger groups (F, I, V) induce larger twist angles between the peptides. Density functional theory calculations on the dimer show the absorption spectrum to be dominated by transitions between carbon and sulfur p orbitals. Although the absorption spectrum is largely insensitive to the relative twist angle, the highest occupied molecular orbital strongly localizes onto one molecule within the dimer at large twist angles, impeding the efficiency of transport between molecules. Our results provide a fundamental understanding of the relation between peptide orientation and electronic structure and offer design precepts for rational engineering of these systems.

Original languageEnglish (US)
Pages (from-to)15221-15231
Number of pages11
JournalLangmuir
Volume35
Issue number47
DOIs
StatePublished - Nov 26 2019

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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