5 research outputs found
Resonant transport in a highly conducting single molecular junction via metal-metal covalent bond
Achieving highly transmitting molecular junctions through resonant transport
at low bias is key to the next-generation low-power molecular devices.
Although, resonant transport in molecular junctions was observed by connecting
a molecule between the metal electrodes via chemical anchors by applying a high
source-drain bias (> 1V), the conductance was limited to < 0.1 G, G
being the quantum of conductance. Here, we report electronic transport
measurements by directly connecting a Ferrocene molecule between Au electrodes
at the ambient condition in a mechanically controllable break junction setup
(MCBJ), revealing a conductance peak at ~ 0.2 G in the conductance
histogram. A similar experiment was repeated for Ferrocene terminated with
amine (-NH2) and cyano (-CN) anchors, where conductance histograms exhibit an
extended low conductance feature including the sharp high conductance peak,
similar to pristine ferrocene. Statistical analysis of the data along with
density functional theory-based transport calculation suggests the possible
molecular conformation with a strong hybridization between the Au electrodes
and Fe atom of Ferrocene molecule is responsible for a near-perfect
transmission in the vicinity of the Fermi energy, leading to the resonant
transport at a small applied bias (< 0.5V). Moreover, calculations including
Van der Waals/dispersion corrections reveal a covalent like organometallic
bonding between Au and the central Fe atom of Ferrocene, having bond energies
of ~ 660 meV. Overall, our study not only demonstrates the realization of an
air-stable highly transmitting molecular junction, but also provides an
important insight about the nature of chemical bonding at the
metal/organo-metallic interface.Comment: 23 pages, 6 figures, supplementary include
Light-Triggered Metal Coordination Dynamics in Photoswitchable Dithienylethene–Ferrocene System
The C-2-symmetric photochromic molecule 3, containing dithienylethene (DTE) and ferrocene units connected by an alkyne bridge, represents a unique probe where a metal (Hg2+) binds with the central DTE moiety. Both photoisomerized states of 3 (open, 3o; closed, 3c) are found to interact with Hg2+ ion by the S atoms of the DTE core; however, the binding constants (from a UV-vis study) and DFT calculations suggest that the open isomer (3o) binds with the metal ion more strongly than that of the closed isomer (3c). Notably, the course of metal binding does not perturb the inherent photoisomerization properties of the DTE core and the photoswitchability persists even in the metal-coordinated form of 3, however, with a comparatively slower rate. The quantum yields for photocyclization (Phi(o -> c)) and photocycloreversion (Phi(c -> o)) in the free form are 0.56 and 0.007, respectively, whereas the photocyclization quantum yield in the Hg2+ complexed species is 0.068, 8.2 times lower than the photocyclization quantum yield (Phi(o -> c)) of free 3o. Thus, the rate of photoisomerization can be modulated by a suitable metal coordination to the DTE core. The dynamics of photoswitchability in the metal-coordinated form of DTE has been explored by experimental means (UV-vis and electrochemical studies) as well as quantum chemical calculations
Zebrafish Neurobehavioral Phenomics for Aquatic Neuropharmacology and Toxicology Research
Zebrafish (Danio rerio) are rapidly emerging as an important model organism for aquatic neuropharmacology and toxicology research. The behavioral/phenotypic complexity of zebrafish allows for thorough dissection of complex human brain disorders and drug-evoked pathological states. As numerous zebrafish models become available with a wide spectrum of behavioral, genetic, and environmental methods to test novel drugs, here we discuss recent zebrafish phenomics methods to facilitate drug discovery, particularly in the field of biological psychiatry. Additionally, behavioral, neurological, and endocrine endpoints are becoming increasingly well-characterized in zebrafish, making them an inexpensive, robust and effective model for toxicology research and pharmacological screening. We also discuss zebrafish behavioral phenotypes, experimental considerations, pharmacological candidates and relevance of zebrafish neurophenomics to other \u27omics\u27 (e.g., genomic, proteomic) approaches. Finally, we critically evaluate the limitations of utilizing this model organism, and outline future strategies of research in the field of zebrafish phenomics. (C) 2015 Elsevier B.V. All rights reserved