Comparative study of anchoring groups for molecular electronics: structure and conductance of Au–S–Au and Au–NH₂–Au junctions

Abstract

The electrical properties of single-molecule junctions, consisting of an organic molecule coupled to metal electrodes, are sensitive to the detailed atomic structure of the molecule-metal contact. This, in turn, is determined by the anchoring group linking the molecule to the metal. With the aim of identifying and comparing the intrinsic properties of two commonly used anchoring groups, namely thiol and amine groups, we have calculated the atomic structure and conductance traces of different Au-S-Au and Au-NH(2)-Au nanojunctions using density functional theory (DFT). Whereas NH(2) shows a strong structural selectivity towards atop-gold configurations, S shows large variability in its bonding geometries. As a result, the conductance of the Au-NH(2)-Au junction is less sensitive to the structure of the gold contacts than the Au-S-Au junction. These findings support recent experiments which show that amine-bonded molecules exhibit more well-defined conductance properties than do thiol-bonded molecules.

A label-free electrochemiluminescence immunosensor based on KNbO3–Au nanoparticles@Bi2S3 for the detection of prostate specific antigen

“…1B showed the SEM images of KNbO 3 -Au NPs, which revealed a homogeneous distribution of Au NPs. Au NPs were well-distributed on the surface of KNbO 3 , which was beneficial for the combination of Bi 2 S 3 and anti-PSA via the Au-S covalent bond and Au-NH 2 covalent bond (Kristensen et al, 2008;Öznülüer and Demir, 2002). Moreover, these Au NPs on the surface of KNbO 3 could also improve the conductivity of KNbO 3 , which was important for immunoassay.…”

“…Bi 2 S 3 can be combined with Au NPs via the chemical bonding of sulfur atom and Au NPs (Kristensen et al, 2008), Then, the reaction solution was separated by centrifugation at 9000 rpm for 10 min. Then, the mixture was dried in vacuum oven at 35°C for 12 h. Finally, the amaranthine product was grinded to powder.…”

“…Au NPs were used to combine with Bi 2 S 3 via the Au-S covalent bond which promoted the electrons transfer and enhanced the ECL intensity largely (Öznülüer and Demir, 2002). Then, anti-PSA was immobilized onto the electrode through Au-NH 2 without the usage of crosslinking agents (Kristensen et al, 2008). The connection between Au NPs and antibody influenced the conductive performance of Au NPs, leading to the decrease of ECL intensity.…”

Effects of quantum interference on the electron transport in the semiconductor/benzene/semiconductor junction

“…On the other hand, some theoretical and experimental efforts, have mainly focused on systems with two metal leads [15][16][17][18][19][20][21][22][23][24] often gold, intriguing physics, oc- * email: javahedi@gmail.com Tel: (+98) 911-1554504 Fax: (+98) …”

Label-Free Electrochemiluminescent Immunosensor for Detection of Carcinoembryonic Antigen Based on Nanocomposites of GO/MWCNTs-COOH/Au@CeO2

“…Au@CeO 2 nanoparticles were well-distributed on the surfaces of GO and MWCNTs-COOH, Au nanoparticles were well for combination with anti-CEA via the Au-NH 2 covalent bond42 . Moreover, Au nanoparticles on the surface of GO/MWCNTs-COOH could also increase the ECL intensity largely, which was important for immunoassay.…”