Observation of Collective Photoswitching in Free-Standing TATA-Based Azobenzenes on Au(111)

摘要

Light-induced transitions between thetransandcisisomer of triazatriangulenium-based azobenzene derivatives on Au(111) surfaces were observed directly by scanning tunneling microscopy, allowing atomic-scale studies of the photoisomerization kinetics. Although the azobenzene units in these adlayers are free-standing and spaced at uniform distances of 1.26 nm, their photoswitching depends on the isomeric state of the surrounding molecules and, specifically, is accelerated by neighboringcisisomers. These collective effects are supported by ab initio calculations indicating that the electronic excitation preferably localizes on then-pi* state oftransisomers with neighboringcisazobenzenes.