Direct Measurement of Electron Transfer through a Hydrogen Bond between Single Molecules

Abstract

Understanding electron transfer (ET) from a single molecule to another single molecule holds essential importance to realize bottom-up molecular devices in which constituent molecules are self-assembled via noncovalent interactions between each other. However, rather little is currently known about the ET properties at the single-molecule interface. Here we employ molecular tips to quantify the ET through a H-bond between single molecules. We found that a H-bond conducts electrons better than a covalent σ bond at short-range. Its conductance, however, decays steeply as the chain length of the H-bonded molecules increases. First-principle calculations were performed to reveal the electronic origin of the facile ET through the H-bond. Our results demonstrate that H-bonding in a molecular junction significantly affects its transport property.

Mechanically Controlled Electron Transfer in a Single-Polypeptide Transistor

“…Hence, we confirmed that water molecules can not only facilitate but also depress ET in peptides, being conditional ET. These observations are consistent with experimental results73. The low ET efficiency of peptides in aqueous solution is mainly due to unfavorable ET pathways.…”

Single-Molecule Electronics: Chemical and Analytical Perspectives

“…MCBJ and I(s) experiments have shown that monothiolated OPE molecular wires can form π-stacking pairs in molecular junctions as long as the molecules are sufficiently long to facilitate strong enough aromatic stacking energetics (Figure 11a) (72,96). The second example is the formation of junctions through noncovalent hydrogen bonds between pairs of facing carboxylic acids (Figure 11b) (97). The third example shows the use of a fullerene molecular tip to facilitate assembly of a single noncovalently linked porphyrin-fullerene dyad (Figure 11c) (98).…”

Molecular Tips for Scanning Tunneling Microscopy: Intermolecular Electron Tunneling for Single-molecule Recognition and Electronics

“…7). 50 The STM tips were modified with SAMs of ω-carboxyl alkanethiols (HS(CH2)nCOOH, CnCOOH; Fig. 1(b), right for n = 2) to prepare the molecular tips, and a gold substrate was modified with CnCOOH.…”