Constructing Dual-Molecule Junctions to Probe Intermolecular Crosstalk

Abstract

Understanding and controlling charge transport across multiple parallel molecules are fundamental to the creation of innovative functional electronic components, as future molecular devices will likely be multimolecular. The smallest possible molecular ensemble to address this challenge is a dual-molecule junction device, which has potential to unravel the effects of intermolecular crosstalk on electronic transport at the molecular level that cannot be elucidated using either conventional single-molecule or self-assembled monolayer (SAM) techniques. Herein, we demonstrate the fabrication of a scanning tunneling microscopy (STM) dual-molecule junction device, which utilizes noncovalent interactions and allows for direct comparison to the conventional STM single-molecule device. STM-break junction (BJ) measurements reveal a decrease in conductance of 10% per molecule from the dual-molecule to the single-molecule junction device. Quantum transport simulations indicate that this decrease is attributable to intermolecular crosstalk (i.e., intermolecular π–π interactions), with possible contributions from substrate-mediated coupling (i.e., molecule–electrode). This study provides the first experimental evidence to interpret intermolecular crosstalk in electronic transport at the STM-BJ level and translates the experimental observations into meaningful molecular information to enhance our fundamental knowledge of this subject matter. This approach is pertinent to the design and development of future multimolecular electronic components and also to other dual-molecular systems where such crosstalk is mediated by various noncovalent intermolecular interactions (e.g., electrostatic and hydrogen bonding).

Mechanically Induced Switching between Two Discrete Conductance States: A Potential Single-Molecule Variable Resistor

“…Compound 1a contains a central ferrocene (Fc) moiety connected to two dihydrobenzothiophene (DHBT) anchoring groups at opposite ends via two rigid alkyne side arms to form a gold–molecule–gold junction, whereas 1b possesses 4-pyridine-anchoring groups at either end. DHBT and pyridine-anchoring groups both form dative interactions with the gold atoms of the electrode by donating the lone pair of electron, and these have been widely used in STM-BJ studies. ,− The incorporation of ferrocene into the bridging molecule allows internal rotation of the cyclopentadienyl (Cp) rings . The low activation barrier for rotation about the central Cp–Fe–Cp axis provides an analogy with a folding ruler so that a variety of conformations may be achieved by stretching and compressing the molecular junction.…”

Ab initio study revealing remarkable oscillatory effects and negative differential resistance in the molecular device of silicon carbide chains

“…When the interchain distance is as small as 2.884 Å, the interaction includes the direct interaction through delocalized π orbitals between the double chains and the indirect interaction through the Au interface, 70,71 which have been observed in recent experiments. 53 As a result, the frontier molecular orbitals near the E f split obviously (see Fig. 3(e1)) and more transmission peaks appear in (SiC) D2–3 n , which are in sharp contrast to the other two cases (see Fig.…”

“…The reason for the choice of SiC and Au is as follows: (1) the SiC chains are regarded as one of the most promising candidates for building blocks of future electronics due to their good conductive capability and high stability for the electron transfer. 11,50,52,53 (2) The Au electrode is preferred in most single-molecule transport measurements 8,10,21,54,55 for its stability and repeatability. In the device, the system is divided into three parts: the left electrode, the right electrode, and the central scattering region.…”

Temperature-Dependent Tunneling in Furan Oligomer Single-Molecule Junctions

“…After naturally cooled in N 2 , Au(111) was immersed in freshly prepared dichloromethane containing a 0.1 mM target molecule for 10 min, then dried in nitrogen gas, and measured in decane in ambient conditions. All of the experiments were performed in a modified Nanoscope IIIa STM (Veeco, U.S.) by using STM break junction (STM-BJ). − The conductance measurements start by moving the tip into the substrate to create a metal point contact. Then the tip is withdrawn from the substrate at a speed of 20 nm/s, and the current is recorded at a fixed bias.…”