The repertoire of potentially useful molecular switches continues to grow as the components that do the switching shrink. A team of German physicists has used a single electron from the tip of a scanning tunneling microscope to transfer a single proton among one of four not quite equivalent positions in the inner cavity of a porphyrin molecule anchored to a silver surface.They have thus demonstrated the smallest conceivable molecular conductance switch. A hat tip to Science Daily for reprinting this press release from the Technische Universitaet Muenchen (TUM) “Targeted proton transfer within a molecule: The smallest conceivable switch“:

For a long time miniaturization has been the magic word in electronics. Dr. Willi Auwaerter and Professor Johannes Barth, together with their team of physicists at the Technische Universitaet Muenchen (TUM), have now presented a novel molecular switch in the journal “Nature Nanotechnology.” Decisive for the functionality of the switch is the position of a single proton in a porphyrin ring with an inside diameter of less than half a nanometer. The physicists can set four distinct states on demand.

Read the rest of this entry »