Tuning the Conductance of Oligopeptides in Single-Molecule Junctions

The development of new materials for advanced electronics applications can directly benefit from precise mesoscale engineering of molecular building blocks. Bio-inspired materials can play a key role in this effort due to their inherent “programmable” structure and function. In this work, we systematically investigate the single molecule conductance properties of oligopeptides with different primary amino acid sequences using a scanning tunneling microscope-break junction technique (STM-BJ). Here, we determine the quantum conductance of all (21) single amino acid residues. We further explore the effect of side chain chemical identity on the charge transport properties of oligopeptides (di- and tri-oligopeptides). In this way, we determine general rules for tuning and enhancing the conductance of oligopeptides. Overall, this work extends beyond prior studies from our group in using chemically modified oligopeptides for the directed self-assembly of π-conjugated units in a precise structural manner. In particular, our work provides key information regarding the conductance and charge transport properties of peptides with various sequences, thereby offering new insight into the electronic properties of oligopeptides that can be used in designing supramolecular electronic materials.