STM-based molecular detection of “catch-and-release” of protons for bipyridine bound to phenylene–ethynylene thiolElectronic supplementary information (ESI) available: cross sectional profiles of the STM images before and after the addition of TfOH. See http://www.rsc.org/suppdata/cc/b4/b402251c/

The protonationdeprotonation response of a novel bipyridine containing phenylene–ethynylene thiol adsorbed to a Au surface was investigated with scanning tunneling microscopy STM, showing reversible changes in the average heights ∼50 spots and the height distribution arising from protonationdeprotonation.