If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.


Analytical Chemistry

A twist on single-molecule conductors

August 28, 2006 | A version of this story appeared in Volume 84, Issue 35

The more an aromatic molecule twists, the less electrical current it can conduct. That's the conclusion of a Columbia University team that has made the first reliable measurements of how the conductance of a single molecule held between two gold electrodes is affected by the molecule's conformation (Nature 2006, 442, 904). Scientists knew that the current passing through such a "single-molecule junction" depends on the molecule's conformation. But these measurements-typically made with thiols or isonitriles-tended to be so variable that there was no way to rigorously test and compare the behavior of different kinds of single-molecule junctions. To make their measurements more reproducible, Latha Venkataraman and her Columbia coworkers studied seven biphenyl diamines that were attached to each electrode via an amine group. The calculated twist angle (q) between the two phenyl rings ranged from 0o to 88o, depending on the molecule's substituents. As the twist angle increased, the degree of π-conjugation decreased, resulting in lower conductance through the molecule. A plot of the data shows that the molecular conductance is related to cos2q, which is what theory predicts.


This article has been sent to the following recipient:

Chemistry matters. Join us to get the news you need.