Completely interfacial photoisomerization of 4-hydroxy-3′-trifluoromethyl-azobenzene studied by STM on HOPG

An azobenzene derivative 4-hydroxy-3′-trifluoromethyl-azobenzene (FAzoH) was synthesized and the physisorbed monolayers of the molecule at the liquid/solid interface were investigated by scanning tunneling microscopy (STM). The acquired STM images exhibit the molecular packing of the monolayers of FAzoH in trans conformation. Following the UV light (365 nm) induced trans–cis isomerization, stable domains of pure cis isomers have been identified by STM. The results suggest that a strong hydrogen bonds network existing in the monolayer stabilizes the domains of the cis isomer.