Intermolecular and Electrode-Molecule Bonding in a Single Dimer Junction of Naphthalenethiol as Revealed by Surface-Enhanced Raman Scattering Combined with Transport Measurements

Abstract

Electron transport through noncovalent interaction is of fundamental and practical importance in nanomaterials and nanodevices. Recent single-molecule studies employing singlemolecule junctions have revealed unique electron transport properties through noncovalent interactions, especially those through a π−π interaction. However, the relationship between the junction structure and electron transport remains elusive due to the insufficient knowledge of geometric structures. In this article, we employ surface-enhanced Raman scattering (SERS) synchronized with current−voltage (I−V) measurements to characterize the junction structure, together with the transport properties, of a single dimer and monomer junction of naphthalenethiol, the former of which was formed by the intermolecular π−π interaction. The correlation analysis of the vibrational energy and electrical conductance enables identifying the intermolecular and molecule−electrode interactions in these molecular junctions and, consequently, addressing the transport properties exclusively associated with the π−π interaction. In addition, the analysis achieved discrimination of the interaction between the NT molecule and the Au electrode of the junction, i.e., Au−π interactions through-π coupling and though-space coupling. The power density spectra support the noncovalent character at the interfaces in the molecular junctions. These results demonstrate that the simultaneous SERS and I−V technique provides a unique means for the structural and electrical investigation of noncovalent interactions.

Spectroscopic Identification of Charge Transfer of Thiolated Molecules on Gold Nanoparticles via Gold Nanoclusters

“…In recent years, plasmonic nanomaterials (i.e., gold and silver) have received tremendous interest in the synthesis and fabrication of hybrid systems, when they are combined with semiconductors, organic materials, or optical nanomaterials . Plasmonic nanostructures have free electrons that not only contribute to the charge transfer process but also induce charge transfer at the interface of metal-based hybrid systems, owing to their unique feature called localized surface plasmon resonance (LSPR). , Charge transfer plays an important role in designing new nanomaterials and many physicochemical phenomena, leading to recent advancements in energy storage, , chemical reaction and catalysts, and biosensors. , …”

“…Charge transfer plays an important role in designing new nanomaterials and many physicochemical phenomena, leading to recent advancements in energy storage, , chemical reaction and catalysts, and biosensors. , Briefly, charge transfer occurs at the interface of hybrid nanostructures, where two nanomaterials form a donor–acceptor pair, and charge in the form of hot electron or hole could be moved from one nanomaterial to another . In recent years, plasmonic nanomaterials (i.e., gold and silver) have received tremendous interest in the synthesis and fabrication of hybrid systems, when they are combined with semiconductors, organic materials, or optical nanomaterials .…”

Intramolecular London Dispersion Interactions in Single-Molecule Junctions

“…A key strategy for controlling electronic transport in a single-molecule junction is to control its conformation, since conformation dictates the strength of conjugation or coupling between electrodes through the molecular backbone . One approach to achieve this conformational control is to incorporate intramolecular interactions such as π-stacking and hydrogen bonding into the single-molecule backbone. − Yang, and co-workers recently described London dispersion σ-interactions to control the association between molecules in stacked supramolecular junctions; yet it remains an open question as to whether these interactions are strong enough to control backbone geometry in single-molecule junctions. Until this point, London dispersion forces have not been observed in single-molecule measurements.…”

Extracting Pesticides from Shallots Utilizing Environmentally Friendly Vapors of In Situ Plasmon-Activated Water

“…SERS effects, composed of electromagnetic and chemical effects, are phenomena that occur at the interface between adsorbates or deposited materials and certain rough metal nanoparticles (NPs). Therefore, SERS spectroscopy can be extensively used to analyze characteristics of various nanosized materials and their catalytic properties, − encoding an approach for biochemical detection, in single-molecule detection, and also in the development of sensors of various species to expand applications of Raman spectroscopy in analytical chemical fields. In 2014, we developed an innovative method to create active, stable, neutral, electron-doped functional plasmon-activated water (PAW) with an intrinsic reduced hydrogen-bonded structure (RHBS) compared with deionized water (DIW).…”