Studies of the molecular switching of azobenzene-functionalized platform adlayers on Au(111) by chronoamperometry

Photochronoamperometry is introduced as a new approach to study isomerization reactions in photoswitchable molecular adsorbate layers on metal electrodes. Using highly ordered self-assembled monolayers of molecular platforms with freestanding vertical azobenzene functionalities on single-crystalline Au(1 1 1) as an example, the photoinduced current response was measured as a function of potential and irradiation intensity and compared to complementary cyclic voltammetry studies. The observed behavior is discussed within a kinetical model that qualitatively describes the experimental findings. In order to describe the intensity dependence, the isomerization reactions, in particular, the thermal relaxation, have to occur distinctively faster than the electrochemical processes, which is in good agreement with previous results for these photoswitchable adlayers. (C) 2013 Elsevier Ltd. All rights reserved.