Solvent Codeposition and Cis−Trans Isomerization of Isophthalic Acid Derivatives Studied by STM

Scanning tunneling microscopy (STM) was used to study physisorbed monolayers of 5-octadecyloxyisophthalic acid (C18ISA) and 5-[ω-(4‘-dodecyloxy-4-azobenzeneoxy)dodecyloxy]isophthalic acid (C12(AZO)C12ISA) at a liquid/graphite interface. The acquired STM images exhibit the molecular packing of the monolayers with submolecular resolution. Monolayers formed by codeposition of solvent molecules and C18ISA or C12(AZO)C12ISA molecules are found when 1-octanol and 1-undecanol are used as a solvent. The cis and trans isomers of C12(AZO)C12ISA, the reagent and reaction product of a reversible photoinduced reaction, are simultaneously present and are both structurally identified at the liquid/graphite interface.