Thermal and photochemical control of an electrochemical process at an isomerizable spiropyran monolayer‐modified Au electrode

An isomerizable monolayer‐modified electrode is used to control interfacial electron transfer by means of external signals. A spiropyran (SP) monolayer undergoes thermal isomerization to the positively charged merocyanine monolayer, MRH⁺, while the latter isomer monolayer is photoisomerized, λ > 475 nm, to the SP‐monolayer state. Pyrroloquinolino quinone (PQQ) is used as redox component for probing the interfacial electron transfer. The MRH⁺‐monolayer electrode attracts the negatively charged PQQ and effective electron transfer is attained. Upon photochemical isomerization to the SP‐monolayer electrode, the interfacial electron transfer is inhibited. Reversible activation and deactivation of the interfacial electron transfer is accomplished by cyclic isomerization of the monolayer through the MRH⁺ and SP‐states, respectively, using thermal and photochemical signals.