Molecular electronics makes use of single molecules to perform electronic functions in a world that increasingly demands smaller, faster, more sensitive and efficient devices. Peptides are an essential part of molecular electronics; they have properties, such as directional tunneling of electrons, high specificity in recognition of substrates and efficient binding of analytes that are suitable for the construction of these devices. Theoretical and computational chemistry provides a fundamental understanding of quantum phenomena at the molecular scale and it is used to describe experimental results, predict physicochemical properties and ultimately, design future electronic components based on molecular systems.<br/>It has been found, through experimental and theoretical studies, that the conductance in peptide chains depend on the secondary structure, the hydrogen bonds, the length of the chain and the amino acids that composes them; however, previous studies have focused on homopeptide chains (peptide chains formed by a single amino acid) and structural changes in conducting molecular systems have shown to modify conductive properties. In this work, we present a theoretical and computational study of the electronic properties and molecular conductance of small chains of heteropeptide amino acids (2-11 amino acids) constituted by alanine homopeptides doped with at least one amino acid from each category: polar, non-polar, positively charged, negatively charged and some special cases. In the same way, we studied the effect of the alpha-helix structure and length in alanine. We performed geometry optimizations of different oligopeptide sequences and analyzed their molecular orbitals using firt-principle calculations based on Density Functional Theory (DFT) using the B3LYP approximation with the 6-311G (d, p) basis set. Solid state electronic devices were setup by connecting the oligopeptides to Gold (1,1,1) electrodes and using DFT at a GGA level and with a DZ basis set we obtained molecular conductance values and current-voltage characteristics. Our results show that negatively charged amino acids increase molecular conductance up to ten times in alanine homopeptides and that positively charged amino acids do the opposite. This work has the potential to contribute to a more rational and optimal design of peptides for their use future electronic devices that can lead to more efficient, cheaper, and robust computational components.

Molecular conductance of oligopeptides in function of their structural properties

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.