Conductance of Single 1,4-Benzenediamine Molecule Bridging between Au and Pt Electrodes

Abstract

We investigated the single 1,4-benzenediamine molecule bridging between Au or Pt electrodes. The conductances of the molecular junctions with the Au−NH2 and Pt−NH2 bonds (Au−NH2 and Pt−NH2 molecular junctions) were 1 × 10−2 G 0 (2e 2/h) and 5 × 10−3 G 0, respectively. The stretching lengths of the Au−NH2 and Pt−NH2 molecular junctions were 0.03 and 0.07 nm, respectively. The conductance value of the Au−NH2 molecular junction was unexpectedly larger than the value evaluated with the density of states of the metal electrodes and the molecule−metal bond strength, which have been discussed before. The large conductance value could be explained by the small energy difference between metal and molecular orbitals (ΔE) and the high degree of π-conjugation (P) of the Au−NH2 molecular junction, which would be unique characteristics of the Au−NH2 bond. The present study showed the importance of these two factors (ΔE, P) in studying the conductance of the single molecular junction.

Conductance of single benzenediamine molecule bridging between Au electrodes

“…When the 4SCP molecule adsorbed on the Au atomic contact, conducting electrons in the contact could be scattered or interfered by the adsorbed 4SCP molecule, leading to the decrease in the conductance of the Au atomic contact [13]. The clear 1 G 0 step in the conductance trace and the 1 G 0 peak in the conductance histogram in the benzenediamine solution indicated that the interaction between the Au atomic contact and the molecule (benzenediamine) with anchoring group of -NH 2 was weaker than the molecule (4SCP) with anchoring group of -SH, which agreed with the previous experimental results [8]. Figure 4 and 5 show the conductance traces and conductance histograms of the Au nano contacts in smaller conductance regime.…”

“…The conductance of the single Au/1,4-benzenediamine/Au molecular junction was determined to be 1×10 -2 (±3×10 -3 ) G 0 under the same experimental condition [8]. The conductance of the single Au/1,3-benzenediamine/Au molecular junction was smaller than that of the single Au/1,4-benzenediamine/Au molecular junction by a factor two.…”

“…1(a)). Details on the experimental design used in this study have been previously reported by our group [6][7][8][9]. The STM tip was made of an Au wire (diameter ~0.25 mm, >99 %).…”

“…To this end, there is great interest in the electron transport through a single molecule bridging between metal electrodes (single molecular junction). The conductance of the single molecular junction has been investigated for various molecules, such as benzenedithiol, alkanedithiol, diaminobiphenyl [2][3][4][5][6][7][8]. While the conductance of the single molecular junctions has been investigated for various molecules, the position of the end group was rather limited.…”

Nanomaterial-based surface-assisted laser desorption/ionization mass spectrometry of peptides and proteins

“…CdTe QDs provided good sensitivity for analytes in the mass range from 330.07 Da to 12 kDa. Among the six nanomaterials, the Fe 3 O 4 NPs and Pt NSPs provided the greatest sensitivity for larger proteins (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) [9,10]. When using the Pt NSPs for SALDI-MS analyses, the batch-to-batch variations for the smaller (Ͻ12 kDa) and larger (12-25 kDa) proteins were 16% and 35%, respectively.…”