Low-Threshold Reversible Electron-Induced and Selective Photoinduced Switching of Azobenzene Derivatives under Ambient Conditions

Mono-carboxyl-functionalized azobenzene and arylazopyrazole have been employed for electron-induced and photoinduced switching under ambient conditions. The microscopic structure and the switching behavior is understood using scanning tunneling microscopy. The carboxyl functional group in these molecules offers low threshold energy for the electron-induced reversible switching compared with nonfunctionalized azobenzene. The low threshold is understood using charged intermediate states during the switching. A selectivity has been observed for the photoinduced switching. Because of strong hydrogen bonding, only the free phenyl groups in the molecules change their configuration.