STM observation of thia[1 1]heterohelicene on gold(1 1 1) and gold(1 1 0) surface

Monolayers of helically shaped aromatic compound, hexathia[1 1]heterohelicene ([1 1]TH), which consists of five benzene rings and six thiophene rings were prepared on gold(1 1 1) and gold(1 1 0) surface under UHV condition. LEED and STM were used for the structural study focused on the molecular chirality. [1 1]TH monolayer on gold(1 1 1) substrate showed the same structure as on (1 1 1) analogue of polycrystalline surface. [1 1]TH evaporated on gold(1 1 0) showed loosely packed molecular chains. The results were compared with the results on gold polycrystalline surface and the bulk structural analysis.