Substituent-mediated quantum interference toward a giant single-molecule conductance variation.

Quantum interference (QI) in single molecular junctions shows a promising perspective for realizing conceptual nanoelectronics. However, controlling and modulating the QI remains a big challenge. Herein, two-type substituents at different positions of-linked benzene, namely electron-donating methoxy (-OMe) and electron-withdrawing nitryl (-NO), are designed and synthesized to investigate the substituent effects on QI.

Controlling Contact Configuration of Carboxylic Acid-Based Molecular Junctions Through Side Group.

In this paper, the contact configuration of single molecular junction is controlled through side group, which is explored by electrochemical jump-to-contact STM break junction. The conductance values of 2-methoxy-1,3-benzenedicarboxylic acid (2-M-1,3-BDC) is around 10 G, which is different from that of 5-methoxy-1,3-benzenedicarboxylic acid (5-M-1,3-BDC) with 10 G. Interestingly, the conductance value of 2-M-1,3-BDC is the same as that of 1,3-benzenedicarboxaldehyde (1,3-BDCA), while single molecular junctions of 5-M-1,3-BDC and 1,3-benzenedicarboxylic acid (1,3-BDC) give out similar conductance value.

Comparative Study of Single Molecular Junctions with -Phthalic Acid and -Phthalic Acid Binding to Different Metal Electrodes.

In this paper, single molecular junctions of -phthalic acid and -phthalic acid with Au electrodes were studied by STM break junction approach. Conductance values of 10 G and 10 G were found for -phthalic acid and -phthalic acid, respectively. The conductance order between -phthalic acid and -phthalic acid with Au is different from that with Cu, which can be contributed to the different coupling between molecules and electrodes; different through-space interaction is proposed for such phenomenon between Cu and Au electrodes.