Voltage-Driven Changes in Molecular Dipoles Yield Negative Differential Resistance at Room Temperature We thank Prof. D. Mandler (HU Jerusalem) for making the hanging Hg drop electrode available to us, Prof. A. Shanzer and Ms. R. Lazar for synthesizing and providing the cyclic disulfide molecules, and Prof. J. M. L. Martin (all from the Organic Chemistry department, WIS), for guidance with the dipole moment calculations. We thank the Israel Science Foundation for partial support. Y.S. thanks the Clor fund for a postdoctoral fellowship.