Switchable Molecular Conductivity

Abstract

We demonstrate the switchability of the molecular conductivity of a citrate. This was made possible through mechanical stretching of two conformers of such citrate capped on and linked between gold nanoparticles (AuNPs) self-assembled as a film. On the basis of experimental results, theoretical analysis was conducted using the density function theory and Green's function to study the electron flux in the backbone. We found that the molecular conductivity depended on the pathways of electrons that were controlled by the applied mechanical stress. Under stress, we could tune the conductivity up and down for as much as 10-fold. The mechanochemistry behind this phenomenon is an alternative branch of chemistry.

Charge Transport in Chain of Nanoparticles

“…The time span for pinning, t p , during which the droplet edge was located at the desired position on the sample, amounted from 5 to 90 s. As a result of the pinning process, (8) and controlled with a sensor (9). After the pinning procedure, the sample was moved with constant velocity, v s , by a motorized translation stage (10). Correspondingly, the droplet edge with the assembled NPs moved with similar velocity into the direction of the nanogap.…”

“…Consequently, the original molecular levels broaden and shift compared to a free molecule in vacuum. For covalently linked citrate molecules on the gold surface, the broadening can be several hundred meV [10]. Figure 4.4 demonstrates that, for charge transport across a chain of nanoparticles and across a single particle configuration, several channels can be identified.…”

“…Electrostatic stabilization arises from the mutual repulsion between the particles due to the negative surface charge of the citrate layer. Switching of the molecular conductance of citrate was demonstrated by Wang et al [10], where they used mechanical stretching of two conformers of citrate capped on and linked between the gold NPs. These conductance change could be achieved by the mechanical stress applied.…”

Conductance Fluctuations in Chains of Particles Arising from Conformational Changes of Stabilizer Molecules

“…Citrate represents a common electrostatically stabilizing agent for gold NPs, because the particles are typically synthesized through a citric acid reduction reaction [4]. Switching of the molecular conductance of citrate was demonstrated by Wang et al [5], where they used mechanical stretching of two conformers of citrate capped on and linked between the gold NPs.…”

DNA−CNT Interactions and Gating Mechanism Using MD and DFT

“…[10][11][12][13][14][15][16] The combination of the chemical sensing capabilities of DNA and the electrical properties of CNT in a hybrid nanodevice has been proposed for very sensitive detection of chemical events at the single-molecule level 17,18 and a molecular understanding of CNT-DNA interaction can yield new insights to develop devices for rapid DNA sequencing 19,20 as well as to improve the development of nanosensors, especially for chemical and biological agents. 5,8,[21][22][23][24][25][26][27][28] Gowtham et al 29 studied the physisorption of individual nucleobases on graphene using DFT methods, finding significant differences between interaction strengths when a nucleobase is physisorbed on graphene; based on an analysis of binding energies, they suggested that the base molecule polarizabilities are the main factors determining the nucleobase-graphene interaction strength. In another study by the same authors, the strength of the interaction was analyzed between DNA bases and a small diameter carbon nanotube of chirality (5,0).…”