LAUSR

Description Voltage pulses offer a way to control single-molecule reactions on a surface To construct complex molecules and molecular devices, tiny, atomic-sized objects must be brought together and connected in a precise way. For better or for worse, this daunting task is still mostly done in a manner likened to putting Lego blocks in a washing machine and hoping that the quintillions of molecules somehow end up assembling themselves into the desired product, either by complete chance or under the guidance of other molecular-sized objects—i.e., catalysts. On page 298 of this issue, Albrecht et al. (1) show how a single molecule can be transformed into three distinct products depending on the voltage pulses from the tip of a scanning tunneling microscope (STM). Notably, the three products can be repeatedly interconverted with a high degree of control.